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Old Jan 31, 2013, 08:03 PM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
2,550 Posts
Quote:
Originally Posted by OVSS Boss View Post
David, I totally agree with your apprasel of F5J and where it can go, and as a very prominent flier told me, F3J is as far as a person can time. And that is the limiter of F3J, not the radios, airframes, etc; it is the timer and the reflex of ones finger to punch that clock. I think that there will finally be a very unique answer to the timing issue for F3J, but it is no where on the near horizon from what I know.

The airframes I think will go as far as designer imaginations and the market will allow. The market and demand are a question I would guess, but guys will have some imaginative solutions.

Marc
Interesting you should mention a solution to the timing problem with F3J. One of the Slovak F5J guys has experimented with a modification of the Altis 3 which marks when the plane releases from the tow on F3J and calculates launch height the same as F5J -- highest altitude between launch and 10 seconds after release. Time is adjusted by measured launch height.

Happy Landings,

Don
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Old Jan 31, 2013, 08:09 PM
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R.M. Gellart's Avatar
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That is there biggest limitation now Don, because the precision that is required to win on the world stage cannot begin to be handled by ones clumsey fingers. Half seconds maybe at best, and they are talking flights that have produced .1-.2 sec difference between window and flight. It is tough, and just like the horns for launch and landing almost is to the point of needing video replay to determine the outcome of a close call. F5J can handle the start of the flight, will be interesting how it plays out.

Is the device you are talking about an external device cause I saw a pic of that but did not her anymore about it.

Marc
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Old Feb 03, 2013, 04:04 PM
Tragic case
davidleitch's Avatar
Sydney Australia
Joined Feb 2002
5,875 Posts
a couple more thoughts, more in the nature of a blog. I now have 4 x 3 metre E gliders

Pulsar 3.2 (setup for Australian LEG comps, Neu 1506 1d TP 2S 3300)
Supra (old version, carbon centre panel, glass tips, Hacker B40 6L+ carbon 6.7)
Egida (Peggy Pepper/skorpion motor, Resienauer gear)
Maxa 3.9 (Kontronik 480)

I also have a winch fuselage for the supra and egida.
On 26 Jan I participated in the Armidale sailplane expo. The electric events were washed out unfortunately. The f3j event was a lot of fun and the hardest day's flying ever (9 rounds in hot sun + seven people flew 3 15 minute finals) 7:00 am to 7:00 pm. I flew the supra broke a tailplane on the first launch and couldn't get going again until after lunch. The supra was competitive in the rounds it flew (finished 5th in the last 5 rounds). Conditions were breezy with strong thermals. If you hit sink on the way back from downwind you could land out pretty easily.

The supra was setup about right for this event.

The next day was very windy about 30 kph all day. Very little lift as the rain moved slowly in, not arriving until round 7. Everyone ballasted up. 400 grams in the Supra. It could penetrate but flew badly. A test flight of the unballasted Egida E in the lunch break showed equal or better performance. At the end of the day just as the rain came I worked out that I'd moved the CG of the Supra back a bit with the ballast which was a disaster in downwind turns, bringing the nose up and killing the energy dead. Lesson learned, but its hard at comps, no time to learn because you are always flying or helping someone else.

Yesterday I tried out the 3.9 metre Maxa Electric in similar wind and very minor rain squalls. It flew backwards without ballast and required motor to get back to field. With 400 G ballast it moved slowly forward but still struggled to stay up. In
7 flights, starting heights 150 - 200 metres best time was about 6 minutes.

Conclusions:

1. You need to make provisions for ballast in your low wing loading F5J glider
2. If using ballast make sure your CG is identical to unballasted or even a bit forward.
3. Landings will be hotter with ballast.
4. Tentative... The Egida and Supra may be better high wind planes than the Maxa.
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Old Feb 04, 2013, 11:29 AM
Registered User
Scotland UK
Joined Jan 2005
276 Posts
Hi
possible solution,
re-motor your Pulsar for F5j light wind days to take slightly longer to climb out
set up Maxa 5-10 mph winds
set up Egida for 10mph +

My set up is
Buzrd up to 7/8 Mph ( see Competitive soaring on a budget thread)
Ballasted Buzrd +200 gms up to 10mph +400 gms up to 15 MPH
Buzrd with Aspire wing weighing 2.35 kgs 10 to 15 mph +
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Old Feb 04, 2013, 12:03 PM
WINS - Winch In Nose Sailplane
jaizon's Avatar
USA, NH
Joined Mar 2008
3,093 Posts
Quote:
Originally Posted by dharban View Post
Kenny,

While there ARE differences in some of the details, the biggest difference between ALES and F5J is that in F5J the competitor gets to choose his launch altitude to make the task time (10 minutes in preliminary rounds). And competitors essentially get time bonus points depending on how low the launch is at a rate of 1/2 point per meter. (Raw flight time equals seconds flown minus 1/2 second per meter for every meter up to 200 and 3 seconds per meter for every meter over 200 meters).

Last year was the first year that the rule was flown and it appears that in a lot of conditions, top tier competitors are CHOOSING to launch for 10 minute tasks to altitudes in the range of 100 to 125 meters. By the time a max flight is normalized to 1000 points, this means that the bonus for launching at 100 instead of 200 meters can be in the range of 75 or 80 points.

While there is nothing in particular wrong with the 200 meter ALES altitude, it is clear that top tier planes are leaving a lot of their performance potential "on the table". The inevitable result of this will be more and more of the top scorers maxing more and more of their flights. And as Marc suggested we will likely evolve to longer tasks and lower launch altitudes.

If our launch altitude was 300 meters, for example, the boxes that most of our planes come in would hang in for 10 minutes MOST of the time. And while I can still rack up 6 minute flights with my Maxa from 200 meters, when I fly it on test flights from 200 meters at dawn, I consistently get 9 1/2 to 10 1/2 minute flights where the Radian is closer to 7 minutes. On any given day when we are not flying "dawn" conditions, the Radian pilot might beat me (yes Paul ). But the new bigger and lighter molded planes will ultimately provide some advantage.

Happy Landings,

Don
Don,

Just to be sure I am understanding you correctly I have a question on F5J scoring. If two pilots fly a ten minute task and one launches to 100m and the other launches to 200 meters and both make exactly 10 minutes, then the one who launches to 100m loses 50 points and the one who launches to 200 meters loses 100 points, a 50 point differential (without normalizing).

And if that is the case, then what performance differences would you look for in an F5J plane over an ALES plane? Or would they pretty much be interchangeable?

Also, it would seem to me that F5J, with the bonus for lower launch heights, might be more interesting to the top tier pilots.
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Old Feb 04, 2013, 12:41 PM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
2,550 Posts
Quote:
Originally Posted by jaizon View Post
Don,

Just to be sure I am understanding you correctly I have a question on F5J scoring. If two pilots fly a ten minute task and one launches to 100m and the other launches to 200 meters and both make exactly 10 minutes, then the one who launches to 100m loses 50 points and the one who launches to 200 meters loses 100 points, a 50 point differential (without normalizing).

And if that is the case, then what performance differences would you look for in an F5J plane over an ALES plane? Or would they pretty much be interchangeable?

Also, it would seem to me that F5J, with the bonus for lower launch heights, might be more interesting to the top tier pilots.
You are correct on the penalty. There would be a 50 point differential in the raw score between the 100 meter launcher and the 200 meter launcher. Once they were normalized this could amount to as much as a 91 point difference between the two competitors. If they both fail to achieve a max, the difference could even be greater.

We will only know how much F5J planes will influence ALES planes once the game really starts, but it seems to that they will be cutting edge for ALES too. One of the things that will be interesting will be when manufacturers start building purpose built F5J planes instead of F3J planes with the noses chopped off. It is clear that for any given size of plane that you can actually build F5J planes that are lighter than their TD cousins. Right now reasonable people might believe that we are approaching the lightest reasonable weights even for our TD gliders. But it might be that F5J airfoils will evolve in their own direction someday and allow very light planes with wider speed ranges and more ability to adjust for ballast.

As to David's observations about light planes and high winds, one of the things that ALES and F5J planes can do in high winds that their TD cousins cannot do is launch substantially greater distances to windward. This may have the effect of keeping more of the playing field ahead of us and allow lighter, relatively less ballasted planes to sink at slightly lower rates before they become unmanagable.

Happy Landings,

Don
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Old Feb 04, 2013, 03:22 PM
Tragic case
davidleitch's Avatar
Sydney Australia
Joined Feb 2002
5,875 Posts
I think the quest for light weight will have limits.

1. Lightweight is generally at the expense of robustness. A competition model leads a hard life, particularly when you are bit hot but still need your landing points.

2. For years myself and other electric glider pilots have been trying to get wing loadings down to the level of our open thermal/F3J counterparts. partly because I thought that I would get better scores if I could just have a lighter model. What I now see is that to an extent that's a mirage. Even on the less windy day in Armidale the F3J pilots were not going for lowest wing loading. For instance one of the pilots on my team chose to fly his 3.5 m Maxa rather than 4 m and he made the finals.

What's important in a comp on any day with thermal activity is to find the thermals and avoid the sink. The ability to cover ground is quite important. That's really the point of the post about wing loadings. We now have the capacity for electric glider wing loadings that are maybe too LOW for average conditions. At least in Australia.
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Old Feb 04, 2013, 03:37 PM
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David, at least for the "average model", there is always a median value that will work best. I do not know of how you could quantify durability, but someone could come up with it I would guess.

I am guessing that you are a guy like me, I fly a fair amount, lots of comps, and keeping a sailplane going is important. But, to those who are going to be playing the game at the WC FAI levels, one ship that is microloaded and can hang at 7:45AM in absolutely calm air, will be in the quiver. It is just what is required I would guess.

Marc
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Old Feb 04, 2013, 05:21 PM
launch low, fly high
New Zealand, Hawke's Bay, Havelock North
Joined Dec 2004
1,792 Posts
I've not a lot of "real-life" experience yet with F5J (yet), as I've flown just a single comp. This comp demonstrated to me that one needs to have good ballast capability, as well as the ability to range upwind on the climb when it is windy. I flew the comp with about 650 g of ballast (Maxa4), so my all-up weight was about 2.5 kg. The wind was about 8-10 m/s with some challenging and tight thermals. I can get about 900g into my Maxa at present, and if I go to lead instead of brass, should be able to get up to 1.2 kg or so

I did learn a bit about the 10s after motor shutoff altitude measurement on one flight. The log showed that I gained ~30m in that 10 seconds. Some of the benefit for an early motor shutdown was negated from the gains in the thermal. It may be difficult to resist climbing for 10 seconds after the motor is shut down, especially when it is windy.

I didn't have any penetration issues, probably because I had enough ballast onboard for the conditions. My experience with the Maxa indicates that it really grows legs with ballast. At the F3J WC in SA last year, I was flying at around 2.9 kg when the winds were at the FAI limit. It was sufficient, although more ballast may have been desirable. F5J may not need quite as much ballast if one can start further upwind. The upwind penetration places a requirement on the propulsion system for a rather fast cruise/climb capability when needed. The nice thing about F5J is that there isn't a launch altitude penalty when adding ballast (assuming that one has enough grunt in the motor). This is different than F3J, and provides for potentially a slightly different ballast optimum.

One thing about going with super-light structure. In the strong winds and with ballast, my F5J Maxa (with the initial uber light spar) shows that scaley wing flex when going through turbulence at speed. Not sure I'd want to be saving much more weight!

That said, I know it can take a 200+m vertical dive with full up at the end (no ballast). This wasn't an intended maneuver. I found that having the rx antennae adjacent to the ESC maybe wasn't the best thing to do, and moved them after having the deficiency starkly demonstrated...
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Old Feb 04, 2013, 06:48 PM
Tragic case
davidleitch's Avatar
Sydney Australia
Joined Feb 2002
5,875 Posts
Joe.

Thanks for those comments. Fantastic to read you are flying an F5J model. Makes me really believe in the potential of the format and that the standard will/has risen very quickly.

For the avoidance of doubt, I take it the comments are for the 3.5 m version of the Maxa?
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Old Feb 04, 2013, 06:57 PM
launch low, fly high
New Zealand, Hawke's Bay, Havelock North
Joined Dec 2004
1,792 Posts
Maxa 4 (3.95m wingspan) is my primary ship. The 3.5 is my short tow specialist... I've bonded with the 4.0 much more than with the 3.5, although some pilots report the opposite so YMMV.
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Old Feb 04, 2013, 07:20 PM
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Question Joe, how many ships are guys allowed in 5J, three like 3J? Do you not think that guys will have the specific light air ship (purpose built for 5J in the 10-20% reduction in weight vs. 3J ships) for the calm or near clam moments and then ships that allow ballasting? My Tragi at this point cannot be ballasted since all the ballasting capablility is removed from the E-fuse.

Marc
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Old Feb 04, 2013, 08:09 PM
Flying = Falling (Slowly)
dharban's Avatar
Tulsa, OK
Joined May 2004
2,550 Posts
Joe,

Thanks for the great information. Guys who know me know that I am pretty much of a putz competition flyer, but I enjoy the company of good flyers and I have an engineer's curiosity and a deep interest in how game theory plays into the things we do. When the first altitude switches came out I started fiddling to figure out what might work in various rule scenarios and how competitors might game the rules. I personally like the F5J rule (although I do have a concern or two from a gamers point of view.)

Right now we are in a phase where we are looking at our TD/F3J paradigm and extrapolating from that experience. It is clear from watching the evolution of F3B and F3J that somewhere along the way that someone will break the old mold. I would observe that the first departures in both flying style and plane design is that we are flying in a much larger field -- our glides will be able to start at any elevation and at any distance which is compatible with our eyesight. And I think, at least in windy weather we will stretch the limits of our familiarity.

I am just finishing my second Maxa -- the one with the servos in the tail. My first one, with pod mounted servos, is still a delight to fly. But laying it out so that it could accommodate 12 or so ounces of ballast resulted in restrictions in the power system that I could fit to something less than 500 watts -- and a lot of futzing to change batteries. The servo-in-tail configuration allows me to easily accommodate 650 to 700 watts without adding any overall weight to the plane. And it will allow me to carry substantially more ballast.

One of the areas that I have spent some time on is seeking ways to design power systems which is a little more direct than methods that are available right now. (I use eCalc for actual motor/battery/prop estimates). And I am finishing details on a simple excel program which allows me to estimate how much power is needed to achieve certain ALES/F5J performance parameters. I call the program the Swagulator and I hope to publish it in RCSD shortly. It allows the user to input plane size, weight and ballast and specify launch altitude, distance to windward, windspeed and motor run time to get a rough estimate of required input power. So far, its results have been in reasonable conformance with observed performance.

My first Maxa at 450 watts will launch to 200 meters, 200 meters to windward in about 25 seconds. This is more or less consistent with Swagulator estimates. To go up and out 200 meters in 25 seconds into a 22 mph (10 m/s) wind with 12 ounces of ballast will take about 650 watts (we should know in a week or two ).

To take the same plane out 400 meters will take about 1150 watts. Interestingly, at this distance we are getting into a regime where drag is a little more predominant than weight so going to 22 ounces of ballast only requires about 1200 watts. 32 ounces of ballast takes you up to 1250 watts and 42 watts takes you up to around 1300 watts. There is a pretty good chance that you could get there with power systems which are still fairly light weight with something like a Neu 1110. Now, if you want to go out 600 meters, drag starts kicking in and you would need to jump it up to 2200 watts.

Interestingly, with the exception of the last case, these performance envelopes can be achieved with a plane which is still very light -- changing batteries and props as you ballast up. I am at a loss to explain why I would want to have the 12 or 13 second motor run that running a high power setup would result in without some change, so I am going to start out on the new Maxa with a 4S 850 and a 14x9 for my high wind setup and a 3S 850 and a 15x8 for my low power setup. These give me around 650 watts for windy and 350-400 for less windy. (Frankly, I don't need the higher wind setups that guys like you do -- I don't have the same competitive fire in my belly that you do or the keen vision. So I will either sit it out when it gets too windy or struggle closer in. But I will get the pleasure of watching guys like you really push these things to the limit.)

Anyway, it is going to be interesting to see where all of this takes us. These planes are definitely fun to fly.

Happy Landings,

Don
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Old Feb 04, 2013, 08:10 PM
launch low, fly high
New Zealand, Hawke's Bay, Havelock North
Joined Dec 2004
1,792 Posts
Marc,

There is far less need for multiple airframes of different construction in F5J. The removal of the string launch aspect really changes the airframe requirements. Where the delta for the flat calm conditions may come about is in regard to the propulsion system. The structure requirements are fairly low in F5J, especially when compared to F3J. So, the light weight airframe can be used for the full range of conditions.

I can see having one plane outfitted with a superlight motor/battery for the early morning light conditions, just enough to get to ~200 m in maybe 25-28 seconds. Of course, it would be the stoopid lite construction, but this may not save substantially compared to the standard F5J airframe. There are more grams to be saved with the motor/battery IMO. That said, I've heard of some lighter construction processes recently that could save some weight that would be applicable to the early morning F5J airframe.

I think that ballast is an essential capability for F5J. The removal of ballast capability on an F5J airframe relegates the plane to fair weather flying. Unfortunately, comps are frequently in less than fair weather!

BTW, if the Maxa gets much below 1800 g, it wants to have a tweaking of the aero... which is in line with some of your prior comments.
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Old Feb 04, 2013, 08:20 PM
launch low, fly high
New Zealand, Hawke's Bay, Havelock North
Joined Dec 2004
1,792 Posts
Don,

Good post!

BTW, my electrified Maxa was originally not meant to be an e-power plane. It has the servos up front, I hacked off the nose and stuffed a motor into it. It is pretty low wattage (~350 W at power-up), but gets to 200 m in around 25 seconds. The prop is likely a bit over-pitched as the climb rate does not seem to suffer much at all with an increase in airspeed. The wattage goes down with the airspeed increase, likely balanced out fairly well by an increase in prop efficiency.

I'm looking forward to trying it with an appropriate battery, at present I'm using a "25C" 3S battery that is seriously not up to the task. Ten seconds into the climb, the battery is down to about 9.1V under load.

BTW, you would be amused with my solution to the fwd cg with the servos and motor up front! The happy part about my solution is that I still have the stock ballast tube available.
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