HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Nov 19, 2008, 07:06 PM
Registered User
Pensacola, FL, USA
Joined Dec 2000
3,235 Posts
Scott,
I read your post this afternoon before going out to the field, so I took some measurements of the walking. We had a Blaster, a Taboo, and my Photon, all 1.5M planes.

We were doing "3-strikes your out." Meaning simulations launch, first two men down is a strike against them. I was the only one using mini hi-start the others were DHL.

There was a good 10 mph breeze and the chute was laying down the line pretty straight. This is very important because it reduces the walking by 40~ 50%.

I could launch higher than the HL's with a max stretch of 40 paces (120'), but to have a fair contest I reduced the stretch to 34 paces (102'). This evened things out with no squawking from HL's. So I walked about 200' per launch.

I hear what you are saying the walking, but when you shorten the length of rubber you reduce the available energy which can only be made up by increasing the diameter which increases the pull. There are limits to that with light planes. And when you shorten the line you get into a situation where the rubber is pulling down on the kiting plane.

All of this can be fairly well calculated by using the work already done on the Charles River site. You may save some money by finding a bulk source for the latex, but one problem is getting a good chute made. The right size is needed, made of good light rip-stop material from kite stores, and as reported, the shroud lines have to be sewn tightly or it just balls up.

The quality of your chute is worth spending time, and money on because with a hi-start it is your greatest device for cutting walking.
Regards,
John255

P.S. The simplest solution to no walking is the e-powered glider. Todays electronics are so light you can get excellent results with 60" planes. I used an Art Hobbies fuse, and Lil Bird wing with a speed 300 motor and folding prop and could stay cruising from thermal to thermal until my neck gave out. I don't use it much because it's too easy. Thermals at 600' are just not as interesting to me.
John255 is offline Find More Posts by John255
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 19, 2008, 07:26 PM
Registered User
Joined Aug 2007
50 Posts
I used to fly speed 400 motors in a converted 2X4 with great results. If there was some way to govern the the motor and battery so it could be fair for everyone. What I have seen when you had a timed motor run that someone would have a extra hot wind and could get twice the altitude. I think that electric could very easily be the answer if it could have strict motor and battery rules.
scottw10 is offline Find More Posts by scottw10
Reply With Quote
Old Nov 20, 2008, 12:39 AM
Registered User
United States, MA, Waltham
Joined Dec 2001
7,112 Posts
While the high start is simpler and cheaper, I think a light winch could be LESS dangerous, at least if you used a spotter, or could wait until no one was within 10 seconds or so walk of the line. You can crank the chute down when you're done so it doesn't drift into anything. That's not usually how it's done, but it's feasible. Especially if you have someone helping you. The high start can fall anyplace.

The retrieve line is another story, plus it's complication, and, while we fly in a public park with them, there aren't very many people walking around, there are more of us, and we generally keep an eye out for people close to the line.

If there are a lot of people in the park, it's time to pack it up and go home.
Quote:
Originally Posted by John255
Lincoln,
Agree you would do better in dead air with winch if the plane can take the center wing pressure. The HL planes I've built are not very well fortified in that area. But the safety issue I was thinking about was not for the plane.

I've never flown in a public park, but I imagine it to be randomly and maybe unpredictably populated with people. The winch has one line going up on the plane and another section running on the ground. The running ground line can cut through a shoe, a foot or any part of a body that falls on it.

Possibly even greater risk is the retrieve line that's lighter, and less visible that drifts downwind. I've seen scary damage to the hood of a car when the line was accidently activated before being cleared.

I doubt that a mini hi-start would cause much harm under any conditions.
Regards,
John255
lincoln is online now Find More Posts by lincoln
RCG Plus Member
Old Nov 20, 2008, 07:56 AM
Proud member of LISF and ESL
LI, New York, USA
Joined Mar 2003
24,464 Posts
Quote:
Originally Posted by John255
Scott,
This really sounds great! Count me in!
So your hope is if there is enough response RCG we may get a dedicated category for 1.5M and smaller.

May be good to start talking about the launch because that determines needed space. You are lucky to have so many large parks.

The term Zip-Start gets used for Hi-Start but they are different. One supplier of The Zip is Aerofoam. It is 15' rubber, and 25' line and can be used in 100' space.
http://www.aerofoam.com/hosemonster.html

I don't have any experience with these, but they sound to me like a lot of pull, lot of speed for jets, etc, and some risk. As you know the smaller HL ships can are hard too hold with a lot of pull. In a public park you also don't need the pin becoming a missile.

Sky Bench makes a good mini hi-start, but I don't recommend it any longer because of price and his high shipping cost.

Probably best may be the Dynaflight Up-Start which is 25' 1/8" ID rubber, 100' line with chute for $28 at Tower.
http://www3.towerhobbies.com/cgi-bin...?&I=LXE637&P=V

This one needs min 300' launch space.
I'm searching for a source for mandrel formed 3/16" thick wall UV protected tubing.

There's not much to building them. Maybe somebody's wife might start a cottage industry for the chutes. I have a small one that works good. Not a wife, but a chute.

I guess that's enough for now.
Regards,
John255

I had these videos that I think illustarate the zip start vs hi-start very well.


Hi-start, up-start, zip start or zip cord

To me a Zip start is a short piece of powerful rubber or bungee cord typically used for high powered launches optimized for speed, hence the name Zip. They typically 10-25 feet of elastic with little or no line. They are often used with flying wings where the hook is in the nose. The plane reaches very high speeds on a flat launch, then is taken straight up at high speeds. Pretty exciting.

F3J pilots use them too. The pull is so strong that the pilot literally has to lean into the plane in order to back up and stretch the rubber. These simulate the powerful pull of a two man tow launch. An example is shown in the video. Note the stance of the pilot as he pulls back.

Zip Start Launches
3D TD (4 min 42 sec)





I think you are talking about short hi-starts or up-starts. These are soft launch devices consisting of about 25 feet of rubber and 75 to 100 feet of line used for launching TD gliders, optimized for altitude rather than speed.

Hi-start launches
RC Glider Flight Compilation (6 min 14 sec)
aeajr is offline Find More Posts by aeajr
Last edited by aeajr; Nov 20, 2008 at 08:10 AM.
Reply With Quote
Old Nov 20, 2008, 08:42 AM
Registered User
Pensacola, FL, USA
Joined Dec 2000
3,235 Posts
Quote:
Originally Posted by lincoln
While the high start is simpler and cheaper, I think a light winch could be LESS dangerous.... The high start can fall anyplace....
If there are a lot of people in the park, it's time to pack it up and go home.
Hey Lincoln,
Sounds like you guys are making a concerted effort for safety in operation your winch because you are aware of the risk. We have three guys here using a winch mounted on a boat trailer which keeps them from man handling the batteries. They love their winch! In fact two of them say they married winches. Your last line says it all for me. However, your winch ideas are important here because everybody has a different situation out there.
Regards,
John255
John255 is offline Find More Posts by John255
Reply With Quote
Old Nov 20, 2008, 09:11 AM
Registered User
Pensacola, FL, USA
Joined Dec 2000
3,235 Posts
Aeajr,

Completely agree with your definitions of the three launchers. I notice you quoted my post which says the ZIP-Start, hi-start and mini (up) start are all different. This has been pointed out also in other post. Maybe Scott is using the term ZIP because he feels it will do away with much of the walking.

This thread started out talking about launching 1.5M and smaller planes. Your videos are great examples of what's going on. One thing I noticed is nearly all of the launches are done by just opening the grip and and let the standard hi-start jerk the plane into the air.

Couple reasons this is not good with the weaker mini/up-start is first you are dumping a percentage of stored energy in the rubber to get the plane to kite speed, and more important without a good heave with the 1.5M HL' the cruciform tail is headed right for the back of your hand. Don't ask!

The picture shows what I'm talking about. The problem is worse if you launch with nose high. However, when you give a good heave with nose slightly above horizon you arm gets out of the way and you get about 20' more launch height.
Regards,
John255
John255 is offline Find More Posts by John255
Reply With Quote
Old Nov 20, 2008, 02:23 PM
Registered User
Joined Aug 2007
50 Posts
Quote:
Originally Posted by aeajr
I had these videos that I think illustarate the zip start vs hi-start very well.


Hi-start, up-start, zip start or zip cord

To me a Zip start is a short piece of powerful rubber or bungee cord typically used for high powered launches optimized for speed, hence the name Zip. They typically 10-25 feet of elastic with little or no line. They are often used with flying wings where the hook is in the nose. The plane reaches very high speeds on a flat launch, then is taken straight up at high speeds. Pretty exciting.

F3J pilots use them too. The pull is so strong that the pilot literally has to lean into the plane in order to back up and stretch the rubber. These simulate the powerful pull of a two man tow launch. An example is shown in the video. Note the stance of the pilot as he pulls back.

Zip Start Launches
http://www.youtube.com/watch?v=IWPoNof0SsQ




I think you are talking about short hi-starts or up-starts. These are soft launch devices consisting of about 25 feet of rubber and 75 to 100 feet of line used for launching TD gliders, optimized for altitude rather than speed.

Hi-start launches
http://www.youtube.com/watch?v=JGvhx...eature=related
You are correct. I had started with the Zip Start as it would take up the least amount of space but someone pointed out that it is too fast for someone that is not used to it and they could destroy their plane. So now it looks like Up-Start or Mini Start is the preferred method. Excellent video's and watched it many times. Thanks
scottw10 is offline Find More Posts by scottw10
Reply With Quote
Old Nov 20, 2008, 03:18 PM
Registered User
Pensacola, FL, USA
Joined Dec 2000
3,235 Posts
With a hi-start you need people with pull.

The videos reminded me of the days when we were doing 3M on a substantial hi-start About three pulls and you were worn out, so we pulled it with the trailer hitch on a car. With a good chute that worked out great.

Last year I went to SouthEastElectricFly and one of the guys had a small scooter with a seat. He let me try it and it was a blast to ride in the mowed grass.

On page 2, post #22, I submitted the idea of using a small electric scooter to pull the mini-start, but got no response. I don't know how small you could go, but a bigger one may be a transportation problem.

This week end may buzz out the the FF field and take a look at their chase vehicles, and how they are transporting them. The FF guys have a walking problem greater than ours.
John255
John255 is offline Find More Posts by John255
Last edited by John255; Nov 20, 2008 at 04:46 PM.
Reply With Quote
Old Nov 20, 2008, 04:13 PM
I'm all about that bass
rdwoebke's Avatar
United States, IN, Indianapolis
Joined Feb 2004
15,068 Posts
Quote:
Originally Posted by scottw10
If there was some way to govern the the motor and battery so it could be fair for everyone. What I have seen when you had a timed motor run that someone would have a extra hot wind and could get twice the altitude. I think that electric could very easily be the answer if it could have strict motor and battery rules.
One way to do it is with these little altimeter circuits. The newer ones have a way to put the circuit between the speed controller port on the receiver and the speed controller. This allows folks to configure a cut off altitude. As long as people don't have crazy high powered planes that would coast a bunch after the motor cuts out, altitudes should be very similar.

Many folks already have or are interested in getting altimeter devices to play with flight logs and such after the flight (post flight analysis) so as time goes on and more of these things are commonplace that could be a good solution.

Ryan
rdwoebke is offline Find More Posts by rdwoebke
Reply With Quote
Old Nov 21, 2008, 03:47 AM
Proud member of LISF and ESL
LI, New York, USA
Joined Mar 2003
24,464 Posts
Quote:
Originally Posted by scottw10
I used to fly speed 400 motors in a converted 2X4 with great results. If there was some way to govern the the motor and battery so it could be fair for everyone. What I have seen when you had a timed motor run that someone would have a extra hot wind and could get twice the altitude. I think that electric could very easily be the answer if it could have strict motor and battery rules.
If you want to equalize the pack, make the motor run very long.

We do a climb and glide at our club. The maximum motor run is 2 minutes. In this way the parkflyers, the weaker electric sailplanes and the hotliners are all equaled out.

In 2 minutes I can sky out my Aerobird parkflyer. A Goldberg Electra, flying on 7 NiCds and an 05 motor can be very high in 2 minutes. My Easy Glider Electric, with a brushless upgrade, hits the same height in 30 seconds. An LMR competition ship will go straight up and leave visual range in about 10 seconds.

You don't have to take the whole 2 minutes, but once the motor is off, it is off and you are now soaring. So in 2 minutes, most pilots are as high as they care to be. Now everyone ie equal and you don't need any fancy equipment to make it work, just a stop watch.
aeajr is offline Find More Posts by aeajr
Reply With Quote
Old Nov 21, 2008, 09:02 AM
Registered User
Fond du Lac, WI
Joined Mar 2005
555 Posts
One way to balance things out is to use the 200 watt/kg (91 watt/pound) rule. With this rule small planes and large planes have nearly the same rate of climb and as a result will reach approximately the same altitude in a given time.
Bob J is offline Find More Posts by Bob J
Reply With Quote
Old Nov 21, 2008, 09:23 AM
Proud member of LISF and ESL
LI, New York, USA
Joined Mar 2003
24,464 Posts
Watts per pound is a good reference point, but there are low efficenty can motor watts, high efficency brushed motor watts, brushless outrunner watts and inrunner/gearbox watts.

They all read the same on the watt meter, but a Speed 400 showing 100 watts will be blown away by a Hacker brushless at 100 watts. And, of course, if you use watts, you need to put a wattmeter on every plane. You need adapters for all the different connectors.

Of courese, you have to weigh every planeat registration, then run the watt test, then do the calculation to get watts/pound.

Of course I can run my "weak" battery for the test but use my "strong" battery for the contest. That will give me an edge.

When it is warm, and the batteries are at their peak, you will get one number. If the batteries are chilled, you will get a different number.

If my plane comes in at 98 watts per pound, based on the test and weigh in, do we add weight to correct this to 91 watts/pound? ("It came in right at 91 last night using my wattmeter on my bench at home. )

Where and how do I add the weight? Now you have to accomodate ballast during the qualification process. They do this in horse racing based on jockey weight.

This can become a highly technical excercise. This is fine for serious competition but not for fun type, "let's have a contest" competition.

Use the long motor run and make it easy for everyone. Cheap planes with cheap motors have an equal chance against hot power set-ups. Therefore there is no incentive to get into a power system $$ race. Run what you brung and let the piloting/soaring skills determine the winner.
aeajr is offline Find More Posts by aeajr
Last edited by aeajr; Nov 21, 2008 at 09:33 AM.
Reply With Quote
Old Nov 21, 2008, 10:07 AM
Registered User
SmokinJoe101's Avatar
Joined Jan 2004
919 Posts
It is funny when we start to talk about competition the word " equalize " starts appearing.

if it's a fun fly then have fun but if the RULES ALLOW then they will be pushed to the limits.

If the event is a 1.5m span with speed 400 2 min run..then you'll have guys with skeeters and multiplex speed 400's and you will have the guys with composite 1.5' and a high $$ motor combo or guys coming up wild ideas with in the rules. It's with in the rules but now the big spenders are needed to be equalized...but this is how we advance the sport, technology and people pushing limits. This is how cool stuff comes to market and we all can enjoy.

Only way is to have a one design with specific plane, motor, prop U get the idea..




sj
SmokinJoe101 is offline Find More Posts by SmokinJoe101
Reply With Quote
Old Nov 21, 2008, 02:17 PM
Registered User
Pensacola, FL, USA
Joined Dec 2000
3,235 Posts
New ideas

The last two post brought up some interesting ideas, some that are new to me. Reading about the different flavors of watts was most enjoyable. And the 2-min. motor run makes a lot of sense.

The idea that everyone will push the rules to the limit I also believe. And, pushing against the limits does definitely advance skill and machinery. Competing also seems to get you out in weather that keeps sane people comfortably at home.

For soaring it appears when looking at all the complexity that HL could be the simplest. No launching equipment just the Tx and the plane, minimum space, usually anything 1.5M or smaller. However, if you can HL a 3M most will take your entry fee. Of course, you still have the big spenders who show up with a carload of $1K ships, but it still takes mastery of reading, and working erratic low-level lift to be in top five.

I guess after that any design 1.5M, or smaller on a mini-hi-start would be next in line for simplicity, probably needing minimum to no rules.

I use the hi-start, but only because I have to. If I could HL I wouldn't be on this thread, and probably wouldn't have learned as much. However, I'm still out in the fresh air, and walking 100' to pick up the line and another 100' to stretch is not so bad unless I listen to the voice in my head that says this part is a PITA.

Regards,
John255
John255 is offline Find More Posts by John255
Reply With Quote
Old Nov 21, 2008, 03:44 PM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
2,646 Posts
Quote:
Originally Posted by rdwoebke
One way to do it is with these little altimeter circuits. The newer ones have a way to put the circuit between the speed controller port on the receiver and the speed controller. This allows folks to configure a cut off altitude. As long as people don't have crazy high powered planes that would coast a bunch after the motor cuts out, altitudes should be very similar.

Many folks already have or are interested in getting altimeter devices to play with flight logs and such after the flight (post flight analysis) so as time goes on and more of these things are commonplace that could be a good solution.

Ryan

I've been testing a ZLOG altitude logger/cutoff switch in an AVA and an E-Blaster to see how they might fit in an altitude limited device. I am working on an article on the results. I think there is a place for these types of devices in some event.

Happy Landings,

Don
dharban is offline Find More Posts by dharban
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Lightest 1.5 M DLG glderguy Hand Launch 26 Dec 03, 2005 07:30 AM
For Sale old red and white mystery 1.5 m glider Ryan Archer Aircraft - Sailplanes (FS/W) 3 Aug 22, 2005 04:59 PM
Yippee! Blade 1,5 m on tuttala.com akita Slope 1 Nov 19, 2004 07:58 AM
Cyberdyne 1.5 M DLG For Sale glider34 Aircraft - Sailplanes (FS/W) 6 Aug 24, 2004 09:17 PM