Paragon Cross Country 2K goal and Return

[rdwoebke]

After nearly 4 years of trying and at least a dozen times in the truck over those years, I finally completed the 2K goal and return task. The day was pretty good. Overnight low was about 42 F and today's high in the mid 70s. Kind of overcast at the time when we started the run, but later on cleared up and puffy clouds. Wind was light and probably predominantly a head wind on the out leg.

I setup my high start and paragon about 12:45 at the Fark Farm in Holland, Indiana with the assistance of Jim Stum, Ed McGinnes, and John Bowles of my model rocket club. They had met me out at the rocket field before the club meeting to try to get this in (finally). First flight was 13 minutes of futility. I was never able to climb above 500 feet. After two more short flights, I felt a big wind shift to the left of the launch area I knew there was lift his way and figured it was strong. A bird in that area did not exactly hurt my confidence... So I launched and went that way. Got in the lift and it was climbing good, so I told John to get the truck started and we hopped in. Well, I sort of flopped in, since I kind of fell over the tailgate and Jim had to remove the hat from my face and pull me onto the truck. I had John start to creep out the driveway and I kept working that thermal. The bird started to go more towards the road and I did too. I was perhaps at 1000-1200 feet at this time and then had John pull onto the road and we were off. I stayed with the bird for a bit then went on course. After about the first Kilometer or so, right before the course goes down into a valley I was low again, perhaps 300 or so feet. I hunted for a bit and found lift and then climbed to perhaps 700-800 since I needed some altitude to get over some high tension wires and then go over a valley (that has a sewage reclamation place) and over to the top of the hill that is the 2K point. I did this and my witnesses confirmed we had gone beyond the goal and then I flew over the sewage reclamation place looking for lift. I hung around this area for at least 10 minutes. During this time, more members of the rocket club including my father started to drive by and stop to help look for lift. I Found a few bubbles that helped me maintain or gain a bit, but not what I really wanted. All this time, I was watching the streamer on my transmitter antenna and the wind was shifting, so I knew something was arriving. I was at or below 200 feet when I found what I needed and it was strong. I climbed in that thermal and had John turn the truck around and start driving back. I climbed to perhaps 1000 feet and we were driving/flying back. When I was within say 500 meters of the launch point I had used up the altitude and was at perhaps 300-200 feet and worried I was not going to make it once again. I had to make a quick decision on stopping and looking for lift or just try to make it. I had John stop a second and watched the streamer. It pointed to the thermal and the thermal was strong. 5 circles and I was good again and John drove back to the launch site and the Paragon followed. By then the entire launch area was up air and birds were everywhere. I was spinning the thing and zooming all over the sky to burn off altitude (I had neglected to plug in spoilers). One of the birds was scooting around the sky following me. I had a wingman! Finally after about 5 minutes of killing altitude I landed within perhaps 35-50 feet of where we launched from.

All in all, a great day of thermals and a great feeling to finally complete this personal goal.

[bryanaw]

Great flight Ryan. It takes a lot of skill to make a flight like that one.

Tony

[rdwoebke]

Forgot to mention, thanks to Mike Boreman for taking the pictures. He had his digital SLR out there and always takes fantastic shots...

Also, that one bird followed me around quite a bit when I was speeding around burning off altitude and was tucking the wings to make speed. I had never seen a bird do that before...


Ryan

[sbxcflyer]

Way to go Ryan. I hope you are ready for the cross country at the Nats next summer. Lets put a team together.
Dave

[rdwoebke]

That is my plan. I have always wanted to fly the XC Nats (I drove for Don Richmond once in the early 00s).

I have a Sagitta XC about half finished that I plan to complete this winter.

Ryan

[John Gallagher]

That is my plan. I have always wanted to fly the XC Nats (I drove for Don Richmond once in the early 00s).

I have a Sagitta XC about half finished that I plan to complete this winter.

Ryan

I realize that you are in the Federal Witness Protection program and that you can't tell us where you live (santa claus), but can you give us an idea where the flight took place?

[John Walter]

I realize that you are in the Federal Witness Protection program and that you can't tell us where you live (santa claus), but can you give us an idea where the flight took place?


Check his first post:

QUOTE:

I setup my high start and paragon about 12:45 at the Fark Farm in Holland, Indiana

UNQUOTE

[rdwoebke]

Hey John,

I am telling you where I live. I live in Santa Claus, Indiana. It is the only real Santa Claus in the country (aka, my postal address is Santa Claus, IN). :)

And, JA is right. I flew from Holland, Indiana. Yes, I know, all these town names sound dubious. So, here is a link to a place in my town:

http://www.holidayworld.com/

I live close enough to this place I can hear the coasters from my yard.

And my rocket club:

http://www.geocities.com/launchcrue/

IIRC, you are sometimes concerned about stuff like this, so more details. This particular XC attempt I did not have a waiver, but often we have an 8,000 foot FAA waiver for rocket launching at our launches (this meeting was rescheduled so we did not have the waiver). The area we fly from is very rural. The XC attempt was done on a county road and the entire time we were on the trip we were only passed by 2 or 3 cars that were not people going to the rocket meeting. I was on course at least 30 minutes. When you travel in my area of the country, you sometimes have to be cautious popping over hills because there might be a slow moving tractor on the other side… So it is quite rural.

Ryan Woebkenberg

[bobby legue]

Congrats Ryan! Im sure you have inspired many others to at least give XC a try. Now that youve completed all your personal goals just carefully pack up the Paragon and send it to me.
Yeah, I didnt think so.
Enjoy,
Bob

[rdwoebke]

Thanks!

Actually, I am not done with the personal goals. This Paragon still has a lot to do. I'm planning on using it for my 8 hour slope and probably my 2 hour thermal. And, it might be a part of some/all of my 20 contestant contest wins...

So it is far from retired! ;-)

I do hope it inspires folks to try XC. Of course, I'm pretty lucky to be living in a rural area (although not really lucky enough to have a 10K course in my backyard). If anybody wants more details on my course, I might have time later today to put some stuff on the map.

BTW, my course was right at 2.05 K.

Ryan

[Forest Flyer]

Ryan,

Congrats on the x-country feat! The flying lately has been very good up here in west-central Indiana, and it looks like you also got some good flying down there in Santa Claus. I attribute this good lift to the “dead standing corn” effect -- fields of dead corn can really heat-up and generate a lot of lift.

As for your quest for Level V status, I can see how you can do the 2 hour flight and the 10K run down there in Santa Claus, but the 8 hour slope flight would seem to require a trip to somewhere not too close. Where were you thinking of going? How will your Paragon do in the wind?

I too have been going for the LSF benchmarks, informally of course, since only electric gliders are practical at my field. The “dead corn effect” led to a 3+ hour flight last weekend on a single 300' climb, by far my longest on a single climb. You should try for your 2 hour flight before the harvest! I’ll have to start thinking about my X-country task. The slope event, however, will take some doing....

FF

[rdwoebke]

Hey Forrest,

I’m still working on my Level 4. I still have some contest points to accrue before it is complete. But, this is a big hurdle I had been stuck on for a while.

I’m personally thinking I’m going to do the 2 hour last on L5. Of course, that is kind of looking far ahead since first I have to get the contest points for L4.

The 8 hour slope flight will likely be done with the Paragon in Brookville Indiana. Brookville is near Cincinnati, about a 3 hour trip for me. Brookville has a big dam by a reservoir that sits above the town and is fantastic lift with south or south west type winds and is workable with north winds too (the rocky lake side of the dam). Many folks have done the 8 hour there. The Paragon will handle the wind fine. Thing is, on the slope the wind compresses in the lift zone and when you are flying the plane, a 15 mph wind is not really like 15 mph on the flat land, it is more like a 10 mph. Plus, you have guaranteed lift (unless the wind shifts or stops) so you can run heavy. I figure the Paragon would slope up to a 25 mph wind. Of course, a 25 mph wind would really wear on the pilots. A number of people have done 8 hour slope flights with Paragons. I was at Brookville when Captain Jack did his 8 hour, it was blowing about 25 mph that day. He and his witnesses/helpers were real warriors.

I don’t think the 10K will be workable in my area. First, for level 5 I need witnesses that are Level 2s. This probably means I would go towards where there are more sailplane enthusiasts although I do have 2 new RC pilots in my area that I am hoping to get on the LSF journey. Second, southern Indiana is hilly/tree infested and the problem is that any country road that would work for XC is not long enough before it dead ends or something. The place I did the 2K for example, the turn around point was right before the start of Holland (say something population 500). Going the other direction I had hoped would work for 10K, but you can only get about 5 or 6 K before it gets unusable. For the heck of it, I am attaching a map of my trip. I have marked the launch point, the turn around point, and the “sewage place” that I referenced in the story. We parked by the entrance (it has a pull off and then a chain link fence) to the sewage place and one of the witnesses in his vehicle drove to the turn around (only about 150 feet away, but up at the top of a small hill and a bit obstructed with trees).

I have a few more ideas for southern Indiana 10K courses, but I think northern Indiana is better for long XC. It is flatter and less tree covered. For example there is a course at the AMA national flying site. There is also a fantastic course in Ft. Wayne Indiana. It is all farm roads and actually the turn around is in Ohio! So that is fun. I was there the day Mike Remus got his 10K on that course.

Ryan

[arukum17]

SUPERB!!!! Well done Ryan...you should really be proud.
Like playing a violin concert.

You and the skies are now one

[rdwoebke]

Thanks Arukum. It makes me a bit more proud that I did this with the Paragon.

XC is really fun. I understand that not everyone is in a part of the world that it is really practical, but it is worth trying some day, even if a person has to drive a few hours to a location where it is rural enough.

That is part of the fun in the LSF tasks for me. It forces me a bit to try out new places and new locations. I always try to share my stories here on 'groups to encourage others to try the LSF program.

Ryan

[Forest Flyer]

....I have a few more ideas for southern Indiana 10K courses, but I think northern Indiana is better for long XC. It is flatter and less tree covered. For example there is a course at the AMA national flying site. There is also a fantastic course in Ft. Wayne Indiana. It is all farm roads and actually the turn around is in Ohio! So that is fun. I was there the day Mike Remus got his 10K on that course.
Ryan,

Have you thought about doing some X-country flying in the reclaimed coal mines between you and Evansvillle? Specifically, the old Ayrshire Mine is to the NE of Evansville and south of I-64. It is (as I recall) a large grassland and thus mostly tree-less (at least no big trees), and there are some county roads through it. Below is the only link that I could find related to this old mine, but it does contain directions.

http://www.indianaaudubon.org/guide/sites/ayrshire.htm

FF

P.S. I don't doubt that the Brookville Dam is the best slope site in the state. It has been some time since I've been there, but I do recall that it is a nice big dam that would indeed be good for sloping.

[histarter]

Doing the 2K Xcountry from a high start is a much greater challange then doing it off the winch. I did my first one with a Paragon carrying ballast from a winch launch; however, my 7K was done with a Shuttle 120 and a histart for a greater thrill of accomplishment! Here's to ya Ryan! :) :)
NOTE: The difference between the winch and histart is the needed climbout ability occuring with the lower airspeed due to the lighter model - that is biased for 'save' technology. At 2000 ft the model can weigh in at 2X empty for 40% more airspeed, better LD, improved damping, and improved handling of more intense thermals. (Making the challange statistically less risky). ;)

[rdwoebke]

I am very familiar with that area, Forrest. My rocket club (funny how it keeps coming back to that group) held 2 rocket nationals at those reclaimed strip mines. For one of them I was a FAI team selection CD.

I'd have to think about that. The witness problem remains though.

Ryan

[rdwoebke]

I don't think I mentioned this earlier, but I was flying the Paragon unballasted yesterday. I have tried it ballasted and unballasted. Yesterday the winds were so light though, I had no problem moving around unballasted.

All of my dozen + XC attempts were done with the Paragon and off my high start. Launches were pretty good, probably ~250-300 or so feet (I had on 100 feet rubber 200 feet line).

Ryan

[rdwoebke]

Thought I'd bump my thread with a picture of the Paragon taken from Sunday.

It looks good in the air. On the ground close up, it shows the 4 years of its life! :-)

Ryan

[bobby legue]

My wife is a little wrinkly also but she still gets most of my good non fly time!
Bob

[rdwoebke]

For your sake, I hope your wife does not read 'groups....

:-)

Ryan

[bobby legue]

Yeah me too. 4 manhattens may not be good before responding to web sites.
Humbily,
Bob

[rdwoebke]

Yeah, that is good advice for us all (to avoid the drinks and posting).

:-)

Hope this inspired some other folks to try XC. You don't need a special ship for short XC. And perhaps some open country and a few buddies to drive.

Ryan

[Ed Franz]

You have got me thinking about my 10K I need to do. This year at Nats should be as good as any time to try it. I know that course all too well.

Ed

[rdwoebke]

I hope to make the XC Nats this year. I have this Sagitta XC that I have had partially complete for like 4 years now.

I still need 3 contests to complete my L4. I had hoped to make the Pumpkin but now I'm pretty sure that is not going to happen.

Ryan

[arukum17]

That picture of the Paragon banking in the first post of this thread is arguably the best Paragon picture ever... if Wikipedia did a write up on the Paragon this is what they should use...

Ed Slobod would be proud!

You've motivated me to go and fix my bungee; install my thermal sniffler and get off my London winter butt

[rdwoebke]

If the Paragon ever comes back into production, we should do a Wiki. :)

Thanks, Mike, the guy that took that shot, is really great with the camera. Ironic thing is I was not really thermalling at that time, it was after the task was made and I was goofing around and burning off altitude. But that Paragon she really loves cranking on a tip like that...

Ryan

[Libelle201B]

After nearly 4 years of trying and at least a dozen times in the truck over those years, I finally completed the 2K goal and return task. The day was pretty good. Overnight low was about 42 F and today's high in the mid 70s. Kind of overcast at the time when we started the run, but later on cleared up and puffy clouds. Wind was light and probably predominantly a head wind on the out leg.

I setup my high start and paragon about 12:45 at the Fark Farm in Holland, Indiana with the assistance of Jim Stum, Ed McGinnes, and John Bowles of my model rocket club. They had met me out at the rocket field before the club meeting to try to get this in (finally). First flight was 13 minutes of futility. I was never able to climb above 500 feet. After two more short flights, I felt a big wind shift to the left of the launch area I knew there was lift his way and figured it was strong. A bird in that area did not exactly hurt my confidence... So I launched and went that way. Got in the lift and it was climbing good, so I told John to get the truck startjusted and we hopped in. Well, I sort of flopped in, since I kind of fell over the tailgate and Jim had to remove the hat from my face and pull me onto the truck. I had John start to creep out the driveway and I kept working that thermal. The bird started to go more towards the road and I did too. I was perhaps at 1000-1200 feet at this time and then had John pull onto the road and we were off. I stayed with the bird for a bit then went on course. After about the first Kilometer or so, right before the course goes down into a valley I was low again, perhaps 300 or so feet. I hunted for a bit and found lift and then climbed to perhaps 700-800 since I needed some altitude to get over some high tension wires and then go over a valley (that has a sewage reclamation place) and over to the top of the hill that is the 2K point. I did this and my witnesses confirmed we had gone beyond the goal and then I flew over the sewage reclamation place looking for lift. I hung around this area for at least 10 minutes. During this time, more members of the rocket club including my father started to drive by and stop to help look for lift. I Found a few bubbles that helped me maintain or gain a bit, but not what I really wanted. All this time, I was watching the streamer on my transmitter antenna and the wind was shifting, so I knew something was arriving. I was at or below 200 feet when I found what I needed and it was strong. I climbed in that thermal and had John turn the truck around and start driving back. I climbed to perhaps 1000 feet and we were driving/flying back. When I was within say 500 meters of the launch point I had used up the altitude and was at perhaps 300-200 feet and worried I was not going to make it once again. I had to make a quick decision on stopping and looking for lift or just try to make it. I had John stop a second and watched the streamer. It pointed to the thermal and the thermal was strong. 5 circles and I was good again and John drove back to the launch site and the Paragon followed. By then the entire launch area was up air and birds were everywhere. I was spinning the thing and zooming all over the sky to burn off altitude (I had neglected to plug in spoilers). One of the birds was scooting around the sky following me. I had a wingman! Finally after about 5 minutes of killing altitude I landed within perhaps 35-50 feet of where we launched from.

All in all, a great day of thermals and a great feeling to finally complete this personal goal.

I know that I have joined this conversation late, but it is good to know that there are some folks that don't want to spend $1K to enjoy X country. The thought that someone should have to spend 1K or more to enjoy XC is really disturbing. (based on my research on this site). With a Paragon, my thoughts and experience are that you can go quite farther. Keep pushing!
Jon

[rdwoebke]

Hey Jon,

Thanks for the kind words. I have had it in my head that I want to do the duration and distance tasks with something that is representitive of "back in the day". That, and I started trying the 2K with the Paragon and I was determined to get it in with the Paragon.

The Paragon is good, but I'm thinking for the 10K I'll want something a bit bigger and a bit quicker. So, I have been building a Sagitta XC from the old Dream Catcher short kit for several years now (big time stalled on it, plan to get back on track this winter). This is a bit newer design but I still think it fits my objective of being similar to how it was done back in the day.

Ryan

[arukum17]

Or a Paragon in XL flavour, as (legit) kitted by German company Modellbau

[rdwoebke]

I stand corrected... Does anyone know if modelbau has a us distributer? The us one I found via the Google only seemed to carry the power stuff from modelbau.

Can anyone comment on the Modelbau kit quality?

That XL version might be nice for XC...

Ryan

[histarter]

Thanks Arukum. It makes me a bit more proud that I did this with the Paragon.

XC is really fun. I understand that not everyone is in a part of the world that it is really practical, but it is worth trying some day, even if a person has to drive a few hours to a location where it is rural enough.

That is part of the fun in the LSF tasks for me. It forces me a bit to try out new places and new locations. I always try to share my stories here on 'groups to encourage others to try the LSF program.

Ryan
The LSF XC has two states for success. Reliability of task, or performance. Your Paragon represents Reliability, and is a neat system that works with histart launchings - and thermal generation savy.

You should do well with the 10K, although the Paragon would take a bit longer on the coarse. [There should be extra credit if a histart is used for these adventures!!] ;) :D

[Libelle201B]

Doing the 2K Xcountry from a high start is a much greater challange then doing it off the winch. I did my first one with a Paragon carrying ballast from a winch launch; however, my 7K was done with a Shuttle 120 and a histart for a greater thrill of accomplishment! Here's to ya Ryan! :) :)
NOTE: The difference between the winch and histart is the needed climbout ability occuring with the lower airspeed due to the lighter model - that is biased for 'save' technology. At 2000 ft the model can weigh in at 2X empty for 40% more airspeed, better LD, improved damping, and improved handling of more
ntense thermals. (Making the challange statistically less risky). ;)
Hello histarter, as I follow this thread back, I read this post. I really don't know why a hi-start launch is so much more challanging than a winch launch. I would hate to think that folks would feel that they have to have a winch, with all it's complexities and cost, to gain maybe an extra 100' feet in altitude. I have launched many a time from a hi-start to gain the altitude needed to find a thermal to begin a XC. I hope you know that some pilots are able to hand launch into a thermal and sky out with a XC size sailplane. So, the altitude at release to find that first thermal really isn't based on the launch technique, it is based on finding that first thermal. A hi-start is good, a winch is better, but not perimount.
I don't want to sound to critical, but where did you came up with the " At 2000 ft the model can weigh in at 2X empty for 40% more airspeed, better LD, improved handling of more intense thermals". The last time I was at 2000 ft, I didn't weigh 320 lbs, and I wasn't doing 40% more than 60 mph, or as you calculate, 84 mph. The L/D is the same, and handling is no different because of altitude, but because of turbulance in the thermal. The same goes for R/C. A R/C pilot would never know any of these factors from standing on the ground. That information I feel is bogus.
Jon

[rdwoebke]

Hello histarter, as I follow this thread back, I read this post. I really don't know why a hi-start launch is so much more challanging than a winch launch.

Jon,

I think his point is that with a really low launch, it is easier/possibly more effective to climb with a lightly loaded plane. When you have a higher launch (his assumption of what a winch would deliver) a person launches into higher areas of the thermals (which should be wider at that alitudude) and a more loaded up plane would in his theory be easier to climb out given the starting altitude.

Whether or not this is true, I'm not sure. I have flown the Paragon at about 45 ounces and at about 75 ounces. The higher WL definitaly covers more ground. On the day I did the task, it was pretty calm and I was not carrying ballast (probably at about 45 ounces).

Ryan

[histarter]

Jon,

I think his point is that with a really low launch, it is easier/possibly more effective to climb with a lightly loaded plane. When you have a higher launch (his assumption of what a winch would deliver) a person launches into higher areas of the thermals (which should be wider at that alitudude) and a more loaded up plane would in his theory be easier to climb out given the starting altitude.

Whether or not this is true, I'm not sure. I have flown the Paragon at about 45 ounces and at about 75 ounces. The higher WL definitaly covers more ground. On the day I did the task, it was pretty calm and I was not carrying ballast (probably at about 45 ounces).

Ryan
Just look at the energy differential between a high start and winch. Nominal tension of the winch is about 5 times the start. Now you are going to launch a 4.7 lb Paragon or an 8 lb XC machine with an average tension at 8 lbs (histart) compared to 35 lb average tension of a winch... Lots of luck, or hope for a heck of a lot of skill to climb out these massive machines using weak thermals below the inversion layer; whereas, the winch will hurl the biggys above the thermal doldrums. Once up, with more potential energy an XC task becomes easier because of greater airspeed. ;)

A meteorological fact is that wind at 2000 ft AGL here in Texas shifts 15 degrees, and is 1.8 times ground speed - typically. I am sure the same state of affairs exist for the entire US - the majority of the time. :)

[Bernd Brunner]

Hi Ryan,

may be i can help...
http://www.mz-modellbau.de/ParagonX.htm

Bernd

[rdwoebke]

Bernd,

Do you distribute to the US? There might be folks interested in buying Paragon kits here....

Ryan

[Bernd Brunner]

Ryan,

that´s not my shop. I´ve just posted the link. The have an online-shop and it seem they are shipping worldwide. SH is 101€, but i don´t know whether the SH-costs are the same for 5 kits on one order. I wrote an email.

Bernd

[histarter]

Bernd,

Do you distribute to the US? There might be folks interested in buying Paragon kits here....

Ryan
Das is fargooden thinken! :D

The big P with a SPICA profile sounds great. The XL appears to be ungainly - I hate to think of the ballast needed. :eek: :eek:

[bobby legue]

PSSST Fellas,
I understand that a person named Ray H is going to release the paragon. Just keep it under your hat for now.
Bob

[histarter]

PSSST Fellas,
I understand that a person named Ray H is going to release the paragon. Just keep it under your hat for now.
Bob
After building 3 of them from 'rustic' kits from a California 'meat packer', a quality version of the big P would surely be appreciated. ;)

[rdwoebke]

The XL appears to be ungainly - I hate to think of the ballast needed. :eek: :eek:

My thought is the Paragon could be a good economically feasable electric sailplane (and competitive, to boot) for folks that don't want to break the bank but would like to get into a large model. With the outrunners out there that are coming way down in price, the power plant does not even have to be outragous (although a good quality setup like the B50 still would be absolute best). I know a B50 Paragon can be built at about 75 ounces and I have an Astro Flight 035 fuselage for my Paragon and it is at about 70-75. At the altitudes electrics like to fly, the extra weight I think is a fantastic thing. The Paragon is a good electric.

So, I'd like to see a kit come back out.

Ryan

[histarter]

My thought is the Paragon could be a good economically feasable electric sailplane (and competitive, to boot) for folks that don't want to break the bank but would like to get into a large model. With the outrunners out there that are coming way down in price, the power plant does not even have to be outragous (although a good quality setup like the B50 still would be absolute best). I know a B50 Paragon can be built at about 75 ounces and I have an Astro Flight 035 fuselage for my Paragon and it is at about 70-75. At the altitudes electrics like to fly, the extra weight I think is a fantastic thing. The Paragon is a good electric.

So, I'd like to see a kit come back out.

Ryan
My friend here in Texas scratchbuilds the big P's, and he too is quite happy with the electric powered ones. :D

[Libelle201B]

Just look at the energy differential between a high start and winch. Nominal tension of the winch is about 5 times the start. Now you are going to launch a 4.7 lb Paragon or an 8 lb XC machine with an average tension at 8 lbs (histart) compared to 35 lb average tension of a winch... Lots of luck, or hope for a heck of a lot of skill to climb out these massive machines using weak thermals below the inversion layer; whereas, the winch will hurl the biggys above the thermal doldrums. Once up, with more potential energy an XC task becomes easier because of greater airspeed. ;)

A meteorological fact is that wind at 2000 ft AGL here in Texas shifts 15 degrees, and is 1.8 times ground speed - typically. I am sure the same state of affairs exist for the entire US - the majority of the time. :)

Hello histarter, not trying to beat a dead horse, but I do agree that a lighter sailplane is at a disadvantage energy wise when considering an 8 lb vs 35 lb launch, bungi vs winch, or when flying on windy days. I personally always used a fairly strong bungi cord. I had all the components for a winch and when all added up $wise, they were quite expensive. Setting up the winch and dealing with the occational spider web tangles ect just made the histart so much easier, for me anyways. As I'm sure you already know, increasing a sailplanes weight does not increase it's best L/D. It's speed however will increase because of the heavier wing loading, and as you say, cover more ground.
As far as the wind is concerned, it all depends on the direction of the wind, its speed and the course of your sailplane in relation to the wind direction. Hopefully your course is down wind which will increase your L/D, upwind will
obviously decrease it.
Happy Soaring
:)

[histarter]

Hello histarter, not trying to beat a dead horse, but I do agree that a lighter sailplane is at a disadvantage energy wise when considering an 8 lb vs 35 lb launch, bungi vs winch, or when flying on windy days. I personally always used a fairly strong bungi cord. I had all the components for a winch and when all added up $wise, they were quite expensive. Setting up the winch and dealing with the occational spider web tangles ect just made the histart so much easier, for me anyways. As I'm sure you already know, increasing a sailplanes weight does not increase it's best L/D. It's speed however will increase because of the heavier wing loading, and as you say, cover more ground.
As far as the wind is concerned, it all depends on the direction of the wind, its speed and the course of your sailplane in relation to the wind direction. Hopefully your course is down wind which will increase your L/D, upwind will
obviously decrease it.
Happy Soaring
:)
The L/D phenomenon is quite interesting. Because of it, the histart becomes a more interesting challenge i.e. striping off luxury to concentrate on the basics.

As the density of the sailplane increases, its airspeed increases [deltaM^0.5 = deltaV] proportionally>re; meaning more mass always increases LD. The limiting factor is more V = more Bank Angle for a thermal size predicated by altitude - thus big sailplanes that have the mass for 3X model velocity can work the upper air (up to 14,000 ft) using the larger thermals while having L/Ds close to 50; while the model (that is considerably cleaner) has an L/D up to 28.

Simply stated: If one were to load a model to weigh in at 9X it would be flying at FS airspeed, and L/D would be closer to 50; however, the small size of the model would translate to needing more cross sectional area to handle and stow the weight challenging the L/D increase. Plus the pilot would need to have the eyes of a hawk to launch the model at 2000 ft to start its upward journey competing with full size machinery i.e. totally in their universe. This is the kind of goal modelers dream about - whereas I stay realistic and just challenge birds using a ½ size histart.

Because of modern mind set, the horse died and is buried! :eek:

[Ralph Weaver]

Isn't "modelbau" German for "Hobby shop". MZ-modelbau would roughly translate to "MZ Hobby shop"

[rdwoebke]

As I'm sure you already know, increasing a sailplanes weight does not increase it's best L/D.


I have heard this too, and I might agree with it (especially from a practical standpoint/noticable standpoint), but as a counterpoint, see this documentation: http://www.charlesriverrc.org/articles/bubbledancer/PDFs/bd_V3.pdf

Notice how he lists max LD at the target weight and then at max ballast weight. LD at max ballast weight increases slightly. Probably not something most pilots would have a way to notice or even measure though...

Ryan

[histarter]

I have heard this too, and I might agree with it (especially from a practical standpoint/noticable standpoint), but as a counterpoint, see this documentation: http://www.charlesriverrc.org/articles/bubbledancer/PDFs/bd_V3.pdf

Notice how he lists max LD at the target weight and then at max ballast weight. LD at max ballast weight increases slightly. Probably not something most pilots would have a way to notice or even measure though...

Ryan
Sorry Ryan, Logic pervades! :cool:
An Albatross weighs in at 42 oz per foot wing area typically and thats only 2.6 lbs/ft. A 25 lb Paragon would be at 52.6 oz/ft or 3.3 lbs. At that point LD would be way in favor of the big P IF structure was Hi Tech to handle the loading. Profile design becomes uncritical (flat bottom, SPICA, or Beachball) - and yes, Dr. Drela could trim a half dozen lbs off the machine with his profiles, for a bit better performance at the airspeed referenced - providing he could handle the stress with his thinner micro controlled sections. Engr 101 [Paper originally submitted to the BARC's Tattler 1994
"The 25 lb Sailplane"] :)

Note: This situation is also the basis for my thesis on 'airspeed being the dominant factor for working a selected altitude range'. Below 500 feet 6 mtr/sec. Above 500 ft 9 mtr/sec. At 2k feet and up 12 mtr/sec.
This paradigm was assembled by statistical math.

[histarter]

To have a bit more fun here, and lets redesign the Big P for working a 2k foot altitude, and up.

Target weight 11.4 lbs. (based upon a simple mathematical projection).
Airspeed nominal 30 mph.
EDA approx 6 degrees (instead of 10).

Tail surfaces non-balanced, but original dimensions, and airfoiled for rigidity. Wing fully sheeted, or foam and glass. Ballast about 5 lbs while centralizing CG and reducing mass inertia problems of intensified structure.
[L/D approx 30 that can be improved upon by Dr. Drela targeting a 12 mtr/sec velocity with more conservative loading using his profile designs].
Note: Spiral for a 20 degree Bank Angle = 300 feet in diameter (meaning a bit insensitive to “gopher belch” lift)! :eek:

Now use an adequate launch system to peak out at 2k ft. (Mount at least 4 power telescopic glasses onto your head). Or Aero tow your machine to base 2k ft and release for 30 minutes of task time (TD competition?). Ops, in less than 5 minutes you will be out of sight of the timer – especially with air pollution increasing! :rolleyes: (And if the timer were an old guy, he would not see you coming off the hook!). At CL 0.25 the Big P will be moving like a powered model at 70 mph to sate XC runs; however, I do suggest passing up a thought of ending flight with a spot landing i.e. to avoid craters forming at the flying field! Hope you get the point of anti-realism; meaning ‘kids don’t try this at home’! :D

[Libelle201B]

The L/D phenomenon is quite interesting. Because of it, the histart becomes a more interesting challenge i.e. striping off luxury to concentrate on the basics.

As the density of the sailplane increases, its airspeed increases [deltaM^0.5 = deltaV] proportionally>re; meaning more mass always increases LD. The limiting factor is more V = more Bank Angle for a thermal size predicated by altitude - thus big sailplanes that have the mass for 3X model velocity can work the upper air (up to 14,000 ft) using the larger thermals while having L/Ds close to 50; while the model (that is considerably cleaner) has an L/D up to 28.

Simply stated: If one were to load a model to weigh in at 9X it would be flying at FS airspeed, and L/D would be closer to 50; however, the small size of the model would translate to needing more cross sectional area to handle and stow the weight challenging the L/D increase. Plus the pilot would need to have the eyes of a hawk to launch the model at 2000 ft to start its upward journey competing with full size machinery i.e. totally in their universe. This is the kind of goal modelers dream about - whereas I stay realistic and just challenge birds using a ½ size histart.

Because of modern mind set, the horse died and is buried! :eek:

Hello again histarter, I'm glad that you are challenging the birds with a 1/2 size histart. The lower you start, the better pilot you will be. :)

[histarter]

Hello again histarter, I'm glad that you are challenging the birds with a 1/2 size histart. The lower you start, the better pilot you will be. :)
At 250 feet of histart altitude [size and weight can be compromised to gain max advantage with a 1/2 size start; empty Mirage, BD, or Paragon a peak state - with ballast added for wind] we have a situation here of finding lift within 2 minutes. As the launch altitude decreases however, the flight becomes more frantic, and luck becomes more evident. At 500 feet and up, flying skill and luck becomes less important, with pilotage and flight planning prime.

So launching to the 250 foot target to work a nominal 6 minute task appears to be a great system to exhibit all the talents needed to demonstrate professionalism - without any concern for man on man! This shorter time base would move a contest much more rapidly while making rewind more reliable with winch systems (shorter lighter lines). NOTE: And the lighter machinery improves safety and landing scores, while making histart pilot training effective for TD events, regardless of the launching system.

[rdwoebke]

I did enjoy the 50 feet rubber data string event when I tried it. I'd like to do more of that some day. For the record, when I did this XC, I went with a full 100 feet of rubber and about 200 feet of line.

Hopefully this thread encourages more folks to try some XC and LSF tasks.


Ryan

[jrerickson]

So launching to the 250 foot target to work a nominal 6 minute task appears to be a great system to exhibit all the talents needed to demonstrate professionalism - without any concern for man on man! This shorter time base would move a contest much more rapidly while making rewind more reliable with winch systems (shorter lighter lines). NOTE: And the lighter machinery improves safety and landing scores, while making histart pilot training effective for TD events, regardless of the launching system.

So why not fly hand launch? Or it the physical exertion of the event seems too much, then hand launch planes off a mini hi start?

No question that flying hand launch increases your flying skill and more importantly, your air reading ability. When you only have enough altitude to make one major flight decision you have to really tune in to what's going on around you, unless, as you say, you are just lucky and stumble into some lift.

What hasn't been mentioned is how low altitude training helps you work lift. This is what separates the good pilots from the not so good. Hanging with a little bubble and making it work for 3 or 4 minutes takes a lot of skill and practice. You balance the decisions of just circling versus ranging out to find the defined edge of the bubble, or leaving it altogether. In a hand launch contest you get this all. The term "frantic" certainly has been used before when you are scratching and a guy 100 yards away is starting to climb.

John

[histarter]

So why not fly hand launch? Or it the physical exertion of the event seems too much, then hand launch planes off a mini hi start?

No question that flying hand launch increases your flying skill and more importantly, your air reading ability. When you only have enough altitude to make one major flight decision you have to really tune in to what's going on around you, unless, as you say, you are just lucky and stumble into some lift.

What hasn't been mentioned is how low altitude training helps you work lift. This is what separates the good pilots from the not so good. Hanging with a little bubble and making it work for 3 or 4 minutes takes a lot of skill and practice. You balance the decisions of just circling versus ranging out to find the defined edge of the bubble, or leaving it altogether. In a hand launch contest you get this all. The term "frantic" certainly has been used before when you are scratching and a guy 100 yards away is starting to climb.

John
Why concern yourself with extremism? Most wish to launch to 1000 feet plus, and you are totally correct on your altitude analysis.

The point you are missing is the fact that sailplanes index airspeed for the band of altitude to be worked. I flew a 3 mtr Mirage in HL, and a light GL, but that was a gimmick that worked when HL was just evolving.

Targeting at about 100 meters instead of 250 meters for a peak launch is simply a better balance for a reasonable airspeed match, and is a compromise to balance out extremism.

[jrerickson]

Why concern yourself with extremism? Most wish to launch to 1000 feet plus, and you are totally correct on your altitude analysis.

The point you are missing is the fact that sailplanes index airspeed for the band of altitude to be worked. I flew a 3 mtr Mirage in HL, and a light GL, but that was a gimmick that worked when HL was just evolving.

Targeting at about 100 meters instead of 250 meters for a peak launch is simply a better balance for a reasonable airspeed match, and is a compromise to balance out extremism.

What extremism? Hand launch? I'm on your side here. I agree that low altitude training improves your flying. You are saying that a Mirage off a half high start is the way to go, I'm saying that tossing a Taboo works on the exact same skill set.

I'm afraid we've drifted off the original XC discussion.

John

[rdwoebke]

I'm afraid we've drifted off the original XC discussion.


If it keeps the thread at the top and people thinking about trying XC or trying LSF tasks, then I'm all for it! :-)

Seriously guys, 2K and 1K is not that far. Most somewhat country flying fields should have enough run to do that and it is a lot of fun.

Ryan

[histarter]

What extremism? Hand launch? I'm on your side here. I agree that low altitude training improves your flying. You are saying that a Mirage off a half high start is the way to go, I'm saying that tossing a Taboo works on the exact same skill set.

I'm afraid we've drifted off the original XC discussion.

John
Actually we are truly stating facts to increase interest in the XC events. ;)

Ryan is doing XC the hard way with a machine that is too light for a 10k adventure. Light is great for duration; however, the majority of flyers out there do not realize how much density is needed to work the upper air (they add 10 ounces to a Paragon and think its hot stuff). Ryan's Paragon appears to be too lightly structured to handle 2 or 3 lbs of ballast, and could use another 10 ounces (at least) of structure to be able to zoom off a winch for a good high altitude start (weighing in at 100 ounces). :)

On a day that has about a 10 mph breeze (preferably erratic) and carrying 20 ounces of ballast for a short but stout histart, would be a good program to attempt a longer XC (knowing he is using duration skills rather than pilotage). If one actually accomplishes the 10k G&A off a short histart, he should be awarded Golden Wings without question because it is a heck of a task!! :D

[rdwoebke]

Ryan's Paragon appears to be too lightly structured to handle 2 or 3 lbs of ballast, and could use another 10 ounces (at least) of structure to be able to zoom off a winch for a good high altitude start. :)


This is probably true. Although the wings are pretty strong. The maximum I have ballasted it to is + 16 ounces. Four 4 ounce bars of clay will fit in the area under the wing (and won't move the CG a lot, but I do have a small weight I tape to the tail to get the CG back where it was) and I have flown the Paragon several times in this configuration (normally > 10 mph winds). I also electric fly my Paragon and although I have not accurately weighed it, I *think* I'm effectivly flying at my + 16 ounce ballasted weight in electric configuration. Perhaps a bit more. I'll have to weigh the two setups some day to find out for sure.

I have a bunch of lead and some day I might make up heavier ballast for my Paragon. I think 32 ounces (or as you suggest perhaps even 3 pounds!) would be pushing beyound the airframe's limits. Perhaps + 24 ounces would be an interesting next step.



Ryan

[histarter]

This is probably true. Although the wings are pretty strong. The maximum I have ballasted it to is + 16 ounces. Four 4 ounce bars of clay will fit in the area under the wing (and won't move the CG a lot, but I do have a small weight I tape to the tail to get the CG back where it was) and I have flown the Paragon several times in this configuration (normally > 10 mph winds). I also electric fly my Paragon and although I have not accurately weighed it, I *think* I'm effectivly flying at my + 16 ounce ballasted weight in electric configuration. Perhaps a bit more. I'll have to weigh the two setups some day to find out for sure.

I have a bunch of lead and some day I might make up heavier ballast for my Paragon. I think 32 ounces (or as you suggest perhaps even 3 pounds!) would be pushing beyound the airframe's limits. Perhaps + 24 ounces would be an interesting next step.

Ryan
24 ounces would be a good step in the right direction.

At 75 ounces your Big P would require a stiff 10 mph breeze to launch i.e. with a full size start; or use a sport winch to haul her up unconditionally. :cool:

Bear in mind that the Paragon profile yields CL 0.6 at zero alpha, so high wind is still an enemy. With CL 1.0 pretty close to max LD, keep her moving steadily on course - saving fast for a downer getaway. :)

On the 10k, just remember that others have accomplished it with a handicapped Paragon (lightly built and truly not sturdy enough) a bit too out of shape to handle the club winch zoom at 100 ounces. :eek:

[Libelle201B]

Obviously there are many different opinions and thoughts on this subject. In R/C soaring as in full scale, there are pilots that concentrate on numbers and formula's when flying their sailplanes, and then there are those that don't worry too much at all about numbers and formula's, and just go out and fly. Whether you use a hi-start or a winch, buy a $2000. or $200. dollar sailplane, it really all comes down to desire, personal preferance and certainly $$$. All to often we see pilots focusing on sailplane performance way before they have learned to be good thermal soaring pilots. It doesn't matter what kind of sailplane you have, how heavy or how light, how high or how low, if you havent learned to thermal and recognize lift, you arn't going to stay up very long and you certainly arn't going anywhere. Over the years I have built many TD, scale R/C sailplanes, from two meters, all the way up to four meters. With many of them I could have gone XC with the proper preparation. My very first XC was with a Sailair, a very large and slow sailplane. I completed 1/2 the course, 6 sm or about 10km without any problem before I ran out of lift, luck and or skill. I would try the same task any day with my little 2 meter Dodgson Sprite from a hi-start, although it would be harder to see. There is really nothing stopping anyone from going XC. If you have the desire, the proper preparation, and a good thermal day, just go for it!
On a side note, there is such a thing as thermal spacing. The higher thermals go, the farther they are apart. This is important for XC. Here in the south eastern USA cloud bases can vary from 2K to about 7K feet depending on the time of year. I don't remember exactly what the formula is, but I think the height of the thermal (cloud base) in feet X 2 or 2.5 also gives you the thermal spacing in feet, divide that by 5280 and that gives you the thermal spacing in statute miles. Thats good news for folks in the eastern USA as cloud bases at 2K should provide another thermal at just about 1 statute mile away. Folks out west need to get lot's of altitude before looking for that next thermal.
Happy Soaring!

[Libelle201B]

I have heard this too, and I might agree with it (especially from a practical standpoint/noticable standpoint), but as a counterpoint, see this documentation: http://www.charlesriverrc.org/articles/bubbledancer/PDFs/bd_V3.pdf

Notice how he lists max LD at the target weight and then at max ballast weight. LD at max ballast weight increases slightly. Probably not something most pilots would have a way to notice or even measure though...

Ryan

Hi Ryan, I would think that if increasing mass or weight was the answer to increasing L/D, we would have some incredibly heavy sailplanes. Because I am not a numbers kind of person, I can't really answer the math equation. I can tell you that others have. Reducing drag is the answer to better L/D. I could load up my 15 meter Libelle with water to it's max gross weight, and still not attain the unloaded max L/D of say a Ventus. They are the same wing span and about same wing area sq foot wise. Drag is the enemy.

[Casey Jones]

LD is not an issue of weight to a certain extent. Within the normal limits of sailplane weight, LD is not an issue, even with a heavy ship. Adding more weight simply makes the peak LD speed higher so you can fly faster without much sink. BUT you cannot increase L/D of an airfoil just by adding weight or taking away weight. L/D is a function of the airfoil and the fuselage, not the weight of a sailplane. Of course, if you have the wing loading of a 747 then L/D is screwed.

[histarter]

LD is not an issue of weight to a certain extent. Within the normal limits of sailplane weight, LD is not an issue, even with a heavy ship. Adding more weight simply makes the peak LD speed higher so you can fly faster without much sink. BUT you cannot increase L/D of an airfoil just by adding weight or taking away weight. L/D is a function of the airfoil and the fuselage, not the weight of a sailplane. Of course, if you have the wing loading of a 747 then L/D is screwed.
Hm, talk about brainwashing?

The specified L/D of a profile is indexed to a Reynolds number. Reynolds number specifies wing chord and AIRSPEED. Doubling the sailplanes mass increases airspeed by 40% for a given alpha, thus Lift ingredient is increasing at a larger rate than drag because of Reynolds, forcing the overall LD higher. At the same time the low alpha bubble is occurring further back on the wing because of the higher velocity - meaning more laminar flow is available, which also adds to better lift efficiency. The LD is increasing at small increments as velocity increases, so is not too apparent with the small weight delta that the majority would believe is effective.

Mathematically the NACA 6409 with an AR of 20 @ 20 oz/ft will perform surprisingly close to an S 7037 - AR 11 @ 14 oz/ft. [Wing area equal] Figures checked out by my genius friend in England, Denis Oglesby.

Drag is bad - but if the aircraft exists, options for using the airframe has diminished. I have witnessed one knowledgeable gentleman mount a fully sheeted wing (12% flat bottom) onto his Windrifter - after packing in 2 lbs of lead; he out flew everything we had because we were flying empty. Yes, we were using the club winch to toss up the 'artillery' (that was just too light).

[jrerickson]

When I flew my LSF 1K I used my TD ship, an Icon. I launched off the club winch to about 500' (we have a short field). I was foolish enough to think I could easily walk along, as 1 K doesn't seem that far. The goal was a church steeple across the wash from our field. My buddy Duke was standing there with a walkie talkie and as I thermalled up and out he was giving me "how close" information. The steeple was straight downwind from my launch position.

Twice I thought I was there, but I was short. I had walked about half the distance when he told me I was clear. I didn't have that much altitude, maybe 500', but I thought that would be plenty to get back home. Wind was 8-10 mph. I hit big time sink. I peeled off 90º to my course and went into search pattern for another thermal. Found one and climbed back out, ironically well past the steeple location. This next time home I put the plane in reflex and pushed the nose down. AOW of the Icon is about 78 oz, but I would have liked to have more for the ride home.

The plane came screaming back and I wasn't back to the field. I was jogging and trying to fly at the same time. Not as easy as I thought it would be. Almost stepping in a couple of holes, going down an little embankment, going through the gate in the fence without hitting my antennae, all the things nobody thinks about that make a task trickier than first imagined.

For the 2K we went out to a desert spot with a lot more room. Took me a couple of tries as the thermals were spotty. Again launched off a club winch to about 500'. This time I had the best XC flyer of all time, Mr. Wurts showing me how it was done. Also had a very stylish rig, a convertible Corvette owned by Mr. Underwood. Wurts made the run in something ridiculous like 4 minutes, averaging over 70 mph. I took quite a bit longer, but made it just the same.

The 10 K was done with a borrowed plane. Greg Norsworthy and Nowell Seigel are good soaring buds that have a ton of XC experience. Greg (LSF V) and Nowell (LSF 4.9) took me out to California Valley, where guys have big contests on the perimeter of a beautiful dry lake bed.

Greg's plane was a simple polyhedral, but with a 176" span. It had a vario. Again, launched off a club winch and because of the weight of the plane, I don't think I was any higher than 400'. I picked up a thermal and it developed, but not strong enough to start out on the course. A little later I jumped into stronger lift and we entered the course at about 1,200'. Greg kept telling me I was way too low, but the plane was looking pretty small to me. I climbed up to about 2,500' and we proceeded to go upwind at about 30 mph. I stopped a couple of times to climb in other thermals, and then when we reached the turnaround I went up to my max altitude, around 3,500'.

This was serious time for me. Ever tried watching your plane nearly overheard as a truck you are sitting in turns around? I almost lost the plane twice. I was in a bean bag chair and that thing had an interesting shape when I was done! As we got re-oriented we headed back to base camp. I just wanted to haul at that point. I had lots of altitude and I wanted to go. Greg told me to watch the speed. He didn't want me to blow the plane up. Good point! Especially with a borrowed plane. We probably averaged about 50 mph on the way back although at one point we got up to 70 mph and I was yelling "Faster" and Greg was yelling "Slower!"

I pulled back on the elevator to slow it down and managed to cross the finish line at about 1,500' I did a couple of loops (again Greg telling me to watch it) before I realized I was being a knucklehead with a borrowed plane.

His plane is plenty stout, but with all that mass the forces get really high.
I slowly circled down and when I landed I was pretty pumped up, but the pro XC guys just gave me a little nod. I mean a 10K in their eyes is nothing more than a tune up. They routinely do over 50K and Greg has done a 100K and Nowell I believe a 75K.

This might sound nuts, but I honestly think on the right day I could do a 10K with a hand launch. It would take awhile, but it could be done. I'm sure you could do it with the Paragon, but you have to be very patient and you need lift with not much wind. Ballast is your friend in XC if the structure can take it.

John Erickson
LSF V #122

[rdwoebke]

Hey John,

Thanks for sharing! Very cool story. Once again, hopefully this inspires some folks.

Personally I'm planning on trying the 10K with a Sagitta XC I'm building (and have been building for about 4 years now). Although I suppose I might consider the Paragon as well, I'm thinking more wing area for this task is a good idea (aka easier to see really high).

But, before I can attempt any 10K, I need to finish my contest requirement for L4.

Ryan

[histarter]

Hi Ryan, I would think that if increasing mass or weight was the answer to increasing L/D, we would have some incredibly heavy sailplanes. Because I am not a numbers kind of person, I can't really answer the math equation. I can tell you that others have. Reducing drag is the answer to better L/D. I could load up my 15 meter Libelle with water to it's max gross weight, and still not attain the unloaded max L/D of say a Ventus. They are the same wing span and about same wing area sq foot wise. Drag is the enemy.
Mass has always been the secret of the expert. Build light and sophisticatedly strong. Use centrally located mass as a motor (Mark Smith, Jim Jones, Lamon Payne, and Joe Wurts) philosophy.

Our profile Gurus have steered us away from the high lift profiles of the past, and thus cut lift so airspeed for a given loading is much higher. Drag by this maneuver has been reduced a bit greater with the lower camber, for an L/D improvement. When the Drela profile is employed for the Paragon (example), you would gain a 30% reduction in needed weight for the same airspeed. 8.75oz/ft for Dr Drela vs 12.5oz/ft for Ed Slobod.

Understand that I am not spearheading the use of corpulent profiles, but simply revealing the expert’s technology for success (when profiles were more primitive). If you own one, this is the way they work – which happens to be the same theorizing for the skinny profiles!

[rdwoebke]

Hi Ryan, I would think that if increasing mass or weight was the answer to increasing L/D, we would have some incredibly heavy sailplanes.

Logically yes and no (ignoring here whether or not there is some L/D increase as a person starts adding a relative lot of weight). To a large degree, modern RC sailplanes are heavily influenced by F3J (and before that F3B). F3B probably has a pretty heavy influenced by L/D concerns. Hence 15 years ago when our competition gliders were mainly influenced by F3B ships, they tended to be pretty heavy (probably composite materials and profiles of the day also had an influence) relative to what is the norm now. We had 90-100 ounce 3 meter planes.... These days, our modern RC sailplanes are more influenced by F3J, and F3J's task has 2 things where weight is a hinderence. First is launch. Not launch height but launch speed. Time on line is critical and one of the primary reasons Drela wanted the Supra lighter by a decent margin than what was common at the time was launch speed. Second is landing. Heavy planes might move around the sky nicely but our landing tasks favors light planes.



Ryan

[histarter]

Logically yes and no (ignoring here whether or not there is some L/D increase as a person starts adding a relative lot of weight). To a large degree, modern RC sailplanes are heavily influenced by F3J (and before that F3B). F3B probably has a pretty heavy influenced by L/D concerns. Hence 15 years ago when our competition gliders were mainly influenced by F3B ships, they tended to be pretty heavy (probably composite materials and profiles of the day also had an influence) relative to what is the norm now. We had 90-100 ounce 3 meter planes.... These days, our modern RC sailplanes are more influenced by F3J, and F3J's task has 2 things where weight is a hinderence. First is launch. Not launch height but launch speed. Time on line is critical and one of the primary reasons Drela wanted the Supra lighter by a decent margin than what was common at the time was launch speed. Second is landing. Heavy planes might move around the sky nicely but our landing tasks favors light planes.

Ryan
Great rational Ryan, but lets stay on track with XC. Your planning to build a biggy for the event, so all your discussion on TD philosophy becomes moot.

My discussion is based upon promoting XC with an existing Paragon design. Modern machines need not be as massive because the issue is airspeed that is limited by thermal demand. Spiral Diameter is directly proportional to delta weight - and this is the limit for massivity! i.e. The size of the thermals to be worked.

[Libelle201B]

Mass has always been the secret of the expert. Build light and sophisticatedly strong. Use centrally located mass as a motor (Mark Smith, Jim Jones, Lamon Payne, and Joe Wurts) philosophy.

Our profile Gurus have steered us away from the high lift profiles of the past, and thus cut lift so airspeed for a given loading is much higher. Drag by this maneuver has been reduced a bit greater with the lower camber, for an L/D improvement. When the Drela profile is employed for the Paragon (example), you would gain a 30% reduction in needed weight for the same airspeed. 8.75oz/ft for Dr Drela vs 12.5oz/ft for Ed Slobod.

Understand that I am not spearheading the use of corpulent profiles, but simply revealing the expert?s technology for success (when profiles were more primitive). If you own one, this is the way they work ? which happens to be the same theorizing for the skinny profiles!
Hello histarter, although I am not a math person, I can fully equate the modern airfoils both full scale and r/c to the fact that "corpulent" airfoils are no longer competitive. Long before the people you mention, there where those that had reached that same conclusion in the full scale world. Thinner, lower camber airfoils at the same weights produced less drag and resulted in better performance. However, I have never seen a full scale glide polar that shows increased l/d with increased weight. If all your equations suggest differently, maybe you should contact ASG, or LS(Grob) and maybe you can start designing their new sailplanes. I know you are focused on r/c, but no one that I know of has produced a data base for r/c glider polars. How could you reach any real conclusions without any real data on any particular glider?
Most of us know from practical experience that the cleaner, less cambered
airfoils will always out perform the thicker "corpulent" airfoils in l/d glide performance. In my oppinion, all the math equations you present to this link only confuse and complicate what should be a reletively easy subject of just going "XC".

[histarter]

Hello histarter, although I am not a math person, I can fully equate the modern airfoils both full scale and r/c to the fact that "corpulent" airfoils are no longer competitive. Long before the people you mention, there where those that had reached that same conclusion in the full scale world. Thinner, lower camber airfoils at the same weights produced less drag and resulted in better performance. However, I have never seen a full scale glide polar that shows increased l/d with increased weight. If all your equations suggest differently, maybe you should contact ASG, or LS(Grob) and maybe you can start designing their new sailplanes. I know you are focused on r/c, but no one that I know of has produced a data base for r/c glider polars. How could you reach any real conclusions without any real data on any particular glider?
Most of us know from practical experience that the cleaner, less cambered
airfoils will always out perform the thicker "corpulent" airfoils in l/d glide performance. In my oppinion, all the math equations you present to this link only confuse and complicate what should be a reletively easy subject of just going "XC".
For some reason I believe the concept of V = M^0.5 is just not understood Libelle201B?
I stick with models because they can handle 4X mass (a concept totally foriegn to full size sailplanes that cannot increase mass more than 25%). This is the same situation as the ant that is is the strongest creature on the planet - for its size!

Fill the ballast tank with sea water on a full size and L/D improvement is totally miniscule because weight delta is still too small - and Re is at least 5X the toy, also minimizing the effect of delta mass. Add to the fact that the flow tends to be conciderably more laminar throughout the higher speed range of the FS machine.

You will notice FS profiles are more corpulent than models because their AR is higher, and the V limits are based on 6 to 10 Gs with torsional strength becoming more difficult to accomplish; whereas, the model's (lower AR) peak can go above 20 G typically (look at the stress in the zoom). The range in Alpha is also greater in full size, increasing available speed range.

For the fun of it take all the drag components off a 747, and its L/D would just about double a top of the line FS sailplane. :eek: At its huge Re, it is a very clean machine. LOL

For thermal lift (?) it would have to spiral over a small city bcause its spiral could not fit within a smaller thermal's diameter. :D

[Libelle201B]

For some reason I believe the concept of V = M^0.5 is just not understood Libelle201B?
I stick with models because they can handle 4X mass (a concept totally foriegn to full size sailplanes that cannot increase mass more than 25%). This is the same situation as the ant that is is the strongest creature on the planet - for its size!

Fill the ballast tank with sea water on a full size and L/D improvement is totally miniscule because weight delta is still too small - and Re is at least 5X the toy, also minimizing the effect of delta mass. Add to the fact that the flow tends to be conciderably more laminar throughout the higher speed range of the FS machine.

You will notice FS profiles are more corpulent than models because their AR is higher, and the V limits are based on 6 to 10 Gs with torsional strength becoming more difficult to accomplish; whereas, the model's (lower AR) peak can go above 20 G typically (look at the stress in the zoom). The range in Alpha is also greater in full size, increasing available speed range.

For the fun of it take all the drag components off a 747, and its L/D would just about double a top of the line FS sailplane. :eek: At its huge Re, it is a very clean machine. LOL

For thermal lift (?) it would have to spiral over a small city bcause its spiral could not fit within a smaller thermal's diameter. :D

Hello histarter, I guess the only formula that I know for sure is:
(LG)+(FT)+(SO)+(SC)=XC
(Launch Glider)+(Find Thermal)+(Sky Out)+(Start Course)= Cross Country

:)

[histarter]

***

[histarter]

Hello histarter, I guess the only formula that I know for sure is:
(LG)+(FT)+(SO)+(SC)=XC
(Launch Glider)+(Find Thermal)+(Sky Out)+(Start Course)= Cross Country

:)
(Launch Glider)+(Find Thermal)+(Sky Out)+(Start Course)= Cross Country (and if too light spend lots of time in the air or land when attempt becomes futile.

I think this is a better program/formula.
(LBG)+(FT)+(CO)+(SC)+(MAL)+(FCT)=XC

LBG= Ballasted glider. CO= Climb out to secure altitude and quickly go onto course (if time is envolved). MAL= Maintain Altitude; above a lower Limit. FC Finish Course Timely. :D

[Libelle201B]

In a XC event some years ago a pilot named Jim entered with his Gentle Lady. The course was about 12 sm total. Everyone else had larger heavier sailplanes some equipped with thermal sniffers. The GL was one of the last to start the course. Eventually everyone including me landed out, not completing the course, except the GL. About an hour or so went by after Jim had launched, and sure enough, here comes Jim, his timer and driver. They completed the 12 sm course much to the imbarrassment of us and our "higher tech" sailplanes.
I bring this story up so that those who don't have the money or expertize to own or build a "real" XC ship, won't feel that anything less is a hopeless venture. Whether you fly a GL, Paragon, or any other TD type sailplane, you CAN go XC. You don't HAVE to have an expensive sailplane with all the bells and whisles, or a cumbersome winch, just a decent hi-start. And it always helps to be proficient at thermaling, and reading the sky. Plus a measure of luck always helps too.
With that, I rest my case.
Happy XC!

[histarter]

In a XC event some years ago a pilot named Jim entered with his Gentle Lady. The course was about 12 sm total. Everyone else had larger heavier sailplanes some equipped with thermal sniffers. The GL was one of the last to start the course. Eventually everyone including me landed out, not completing the course, except the GL. About an hour or so went by after Jim had launched, and sure enough, here comes Jim, his timer and driver. They completed the 12 sm course much to the imbarrassment of us and our "higher tech" sailplanes.
I bring this story up so that those who don't have the money or expertize to own or build a "real" XC ship, won't feel that anything less is a hopeless venture. Whether you fly a GL, Paragon, or any other TD type sailplane, you CAN go XC. You don't HAVE to have an expensive sailplane with all the bells and whisles, or a cumbersome winch, just a decent hi-start. And it always helps to be proficient at thermaling, and reading the sky. Plus a measure of luck always helps too.
With that, I rest my case.
Happy XC!
My first adventures in XC was with a Legionair that I flew empty. It kinda worked until I built the Shuttle 120. With ease of access to ballast, the tasks became a lot easier because of the following reasons:
FF stability imporoved.
Controls were sharper in responce.
Conversion of energy (kinetic to potential) more regulated.
Faster extraction from a downer.

This makes the activity more fun and more reliable. I did similar with a GL that weighed in at 39 ounces. In dead calm I would take the 8 ounces of ballast out or use the sport winch to crank her to altitude. :D

Having a flight plan can make this activiy much more enjoyable. :D