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Sep 23, 2019, 03:50 AM
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Quote:
Originally Posted by BirrenP
Should've learned my lesson from static line towing hang gliders, that tow line will break more easily when it lays on a bump or rise in the ground and tension is applied. My brand new HD hi-start was laid out on uneven ground and it broke while tensioning for a third launch. Tied a grapevine knot. Retensioned (or tried to). Broke again a foot from the knot. Lesson learned.
Just how rough is that ground? I haven't had too much trouble with slightly uneven ground.

Was it brand new as in recently manufactured or as in never used before?

What brand is it, exactly what size is it, and how hard did you pull? (Or what length of rubber and how many steps?)
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Sep 23, 2019, 05:42 AM
dare to thermal
Yes, highstarts can be challenging...
We are using highstarts for F3J like contests called "sommerliga".
https://www.rcgroups.com/forums/show...ght=sommerliga

Due the fields we can use we are facing the same challenges due to turning winds etc.. What has happend this season, are some changes in launch technicque used by some competitors.
The maximum energy in the launch system is stored in the stretched rubber. In tail wind no more energy will be added. The onyl thing you can do is using "short launches". The energy in the rubber is used to gain speed. Then the speed can be converted into hight. Hanging on the line until all the energy has gone, isnエt the best idea in those conditions.

btw. what kind of sailplanes do you launch?
Sep 23, 2019, 06:10 AM
Registered User
I've just finished reading this thread and wanted to provide a bit of a counterpoint to the "electric is better for contests" perspective. Although, of course, just for perspective, at the end of the day we're all entitled to our own opinions and the variety is the spice of life. I want to base my comment on this:

Quote:
Originally Posted by Randy Reynolds
I don't think our worst problem is the retrieving actually although we have five-six of us who have limited abilities to do so for an entire contest. Rather it is what happens when the wind direction and velocity depresses the launch to as much as 40% of what it could be. This adds too much variability in the form of gambling risk to the results. The best flyer in our club in unlimited TD flying often places well down the list in F3-RES and while he is not complaining, he is very frustrated. He is frustrated because the launch method can put you off the podium in spite of your best efforts.
Personally, I don't see the "challenges" of hi start launches as a deterrent. Rather, quite the opposite. It becomes another variable. A variable which pilot skill can have some influence over - some people will be good at launching downwind (or whatever) because they've practiced and built that skill. Some people will get stuck with a bad launch and will really have to stretch their thermal capabilities.

When you can't count on the launch being consistent, it makes things much more variable. All too often, people organizing contests seek to make everything consistent, in the interest of being "fair." I understand that, and of course, in general, variables outside anyone's control would ideally be consistent.

But the very nature of a CONTEST is the idea of pitting skill against skill. And if a contest is designed to be SO consistent that there is very little room for skill to make a difference, it stops being interesting.

Some people think that electric motors (limited to run time or launch height) are good because they level the playing field. But I think there's room for the opposite to be true. Hi start launches are good because they give the pilot another potential skill to develop. Anyone can motor a sailplane up until they hit their limit and the motor cuts out, but not everyone can get a good high energy release from a hi start in bad conditions.

I remember going to the Nats for the first time in the mid 90's and doing the open category LMR electric sailplane contest. It was my first real sailplane competition against actual experienced pilots. After watching others and seeing the results, I realized that with a powerful motor and a good glider, you didn't really need to even thermal to hit the duration target. Just launch, run the motor for X seconds, and let it float back down. In a sense, it was exciting to be there competing with people of such skill, but it also felt really anticlimactic.

You can kill a contest format by making it SO fair that it stops being fun. You can also kill it by having so few rules that people exploit the system. The best contests are in the middle. Enough random variation that it's not always the same, there are surprises sometimes, and people have to react. People will have their own feelings about where on that spectrum a difficult launch method (like hi starts) is, but call me an optimist, because for me, the difficulties of a hi start launch add to the "fun." So before a club thinks about throwing in the towel on a hi start launch contest and switching to electric, maybe there is some fun to be had trying to learn to deal with the hi starts. Or maybe life is just too short and you really should toss them!
Sep 23, 2019, 07:08 AM
Registered User
I enjoy the hi-starts, but realize they are not to everyone's taste. For me, the advantages are minimum cost combined with a consistent launch, that gets my cheapo F3RES glider pretty high enough, usually. I regard a good launch as nice, but I flew far too much f3k in my day to be upset at a lesser launch.

In my neck of the woods, we are usually much more interested in flying than launching, so we do not spend a lot of time exactly aiming our hi-starts directly at the wind. Cross-wind launches are considered a basic skill here in Albuquerque. Downwind launches are tolerated, but everybody launches, THEN we shift the line.

One of my highlight flights here at home was last year at the Balloon Park. As the countdown to the window went on, everybody was anticipating a good launch. But the breeze was not typical for the morning, and I decided to treat it as a passing thermal. On the horn, everyone else released, but I held on... And kept waiting. Sure enough, the breeze paused at maybe 1:20 in the window, and I released into slack air, but directly into lift. Everyone else was scrambling back from downwind, for a relight. I am not often that observant.

I flew f3k just as long as I could do so, without being an embarrassment. I enjoyed the visceral feel and immediate feedback from every launch. I still do, but I have become old. Now, the simple (but very efficient) F3RES airplanes give me the same experience, but put me back into contention. Plus, I enjoy building. Plus, I enjoy the fact that with all the airplanes out there, the F3RES venue is not yet an arms race. You cannot buy a win, you must build it and fly it

I have enough arthritis, enough injuries, enough she and experience to know that chasing a hi-start will one day no longer be a option. If I plan right, I should also not be able to safely fly at all once my legs give out. So, if the number of launches I have remaining is indeed finite, I intend that that number be large. Just as I worked hard to make the number of f3k launches I had in my life time to also be large.

Greg
Sep 23, 2019, 07:19 AM
Sonoran Laser Art
From what I have seen a spec F3RES high start is only good into the wind. You have 15M rubber and 100M line for a total of 115M. The rules say you can't stretch beyond 145M total length. I'm not seeing any that get close to the 4kg pull with 30M stretch. So now you have about 7 lbs and 30m to pull that 100m line. All the rubber I have used takes closer to 3x pull to get close to 4kg.

We are limited by a small field and use 10m rubber and 50m line. At 3x pull we get just over 8lbs pull. The rules do say you can shorten the line but can't pull over 4kg-fine.

So now maybe it's why we're breaking 50 lb mono. That gets fixed this week.

Unless your field is big and the wind does a 180 moving long lines can also be a challenge. The key is they all match and there is room in the rules to adjust to smaller fields which can definitely help IMO.

One more thing
I have seen two rubbers that are not very elastic. 2x stretch and they firm right up. You need rubber that stretches consistently to 3x. The old HK blue was good but it's changed and too stiff now. The DJ Aerotech rubber is nice.
Last edited by CloudSniffer; Sep 23, 2019 at 07:53 AM.
Sep 23, 2019, 09:58 AM
Overkill is underrated
elac2az's Avatar
It’s been mentioned that more energy is obviously needed in those moments of a downwind launch. I won’t pretend that this suggestion is the answer to Randy’s desire to conquer the shifting wind problem when using a high-start in a contest situation. But here goes anyway...
If the pull-back line for your high-start under calm to headwind conditions is, say, 20 paces, how about having a second pull-back line, something like 25 paces, identified. And the CD or a line judge can simply call out when the pilots are to use the second, further launch point in the interest of more energy to overcome some the launch altitude losses involved when the wind shifts and a downwind launch is going to result.
Respectfully submitted, Ed
Sep 23, 2019, 01:00 PM
Registered User
Randy Reynolds's Avatar
Thread OP
<<btw. what kind of sailplanes do you launch? >>

Hello Bernd, In our club we have two Slites; one Samba, four X-res; three Yellow Jackets; one Opal and one Mad-res.

Five contests this year: First was the Postal flown in high, cold winds of shifting direction; Second later in the year also flown MoM in high winds; Third flown in almost no wind and direction changes so we couldn't really change HiStarts....40m launches halfway through some rounds. Fourth flown Open winch with 14 pilots ....we tried splaying the HiStarts to anticipate wind changes. Best F3-RES contest: Fifth contest with 15 contestants....highly variable wind including 180 permanent shift flown Man on Man. One more contest to go in October. Not an endearing season experience for our first go at F3-RES

We do allow electrics in order to have more participation. Typically only one entrant per contest. Next year there will likely be several converted F3-RES designs. I appreciate that there is technique to be learned in problematic conditions that the HiStart is poorly adapted to. In considering our contest experiences this year we seem to have highly variable wind direction and velocity. Also we fly at near 7000' altitude and I wouldn't know what that might mean. We do fly from a sod farm and usually it is best to fly off the green grass to surrounding areas to find lift. When you have a 40-50 meter launch you're not going to get off the field to find any lift generally. My Slite is a very good performer so when it yields two minute or less flights it can get frustrating. Isn't it the same for everyone? Perhaps, if your club flys MoM with several lines out.

I did mention that earlier in the year we flew an event for electric two meter sailplanes in sort of a mini ALES format. Except we flew all up, last down with flyers announcing when they were down with a scorekeeper noting the finishes. We flew 12 pilots and flew 5 rounds in well under two hours that included a 180 degree wind direction shift. The winner was an 82 year old long time sailplane pilot who has no chance of chasing HiStarts. This likely was the best contest of the year for our season. Sign of the future?
Sep 23, 2019, 01:16 PM
Registered User
Randy

So, when is your October contest? If the Desert Dust-up doesn't pan out, I'd like to come up.

I will bring a couple of hi-starts (one F3RES compliant, one that is zippier). I have been pretty happy with the way my airplanes launch, plus Albuquerque is also pretty high (which in my experience between the Rockies, Arizona, Indiana and now Germany) does not really make much difference). I can usually be there Friday afternoon, if anyone just wants to try different launch techniques

Yours, Greg
Sep 23, 2019, 03:09 PM
Registered User
Randy Reynolds's Avatar
Thread OP
Greg, Our last F3-RES contest is Oct 5th and John Read is the CD. You are most welcome to come and participate in our contest. Good weather is declining and typically the wind velocity has picked up during the Fall as I'm sure is the case in other locations.

Our HiStarts are DJ Aerotech rubber and braided nylon with small parachutes from Mr. Kite. Our first HiStart I bought from Josef with our group order of Slites that we used as a benchmark. DJ apparently did it's homework as we didn't see any difference in performance. It originally had monfiliment line which eventually was replaced with braided nylon. When HiStarts are set up we do tension them with a fish scale to the regulation 4 kg pull. Sailplanes have varying vertical performance depending on the owner of course.

Since last year when we ran three trial F3-RES contest plus a Postal , I believe we have had 10 contests and numerous practice sessions and while our skills have evolved I'm sure we can learn new techniques.
Sep 23, 2019, 04:00 PM
Overkill is underrated
elac2az's Avatar
Randy, it would sure be nice to see you and a number of your crew come to the Desert Dust-Up. Great site! Have you checked out our contest thread?
https://www.rcgroups.com/forums/show...nfield-Arizona
We need pilots to make this inaugural event happen. It will make a great tune-up for Greg’s event in November.

Ed
Sep 23, 2019, 04:38 PM
Registered User
Randy Reynolds's Avatar
Thread OP
Ed, I値l certainly put your contest on our club group email. We just concluded our most important contest of the year which was the Colorado Challenge Cup with our sister club RMSA so we値l have to see how much of the competitive juices are still flowing.

There has been discussion about simply stepping back a certain number of paces in order to gain more tension in certain conditions. We値l have to give that a try next season. We値l have to sort out when to do that in a round in order to be as fair as we can. Rest assured Mother Nature will do her best to foil our plans :0)
Sep 23, 2019, 07:24 PM
Registered User
At 7,000 feet, you'd probably have better contests with somewhat longer or stronger rubber. Your air is something like 19 percent less dense than sea level air. Contestants near the Dead Sea, OTOH, at -1,400 feet, should use shorter or weaker rubber. ;-)
Sep 23, 2019, 09:23 PM
I sink, therefore I am...
espe's Avatar
It would seem to me, that the opposite would be true... Lighter HiStart at altitude, stiffer at the Dead Sea, if you were hoping for a uniform result.

Just curious.

Sam
Sep 23, 2019, 10:03 PM
Keep looking up!
BirrenP's Avatar
That particular spot had a 10-foot rise over about 150 feet.

The whole kit was just purchased from Tower Hobbies, so recently made -- had to wait several months for delivery.

It's 5/16 OD / 1/8 ID, pulled to 10lbs and 11lbs. 100 feet of silicone with 250 feet of line.



Quote:
Originally Posted by lincoln
Just how rough is that ground? I haven't had too much trouble with slightly uneven ground.

Was it brand new as in recently manufactured or as in never used before?

What brand is it, exactly what size is it, and how hard did you pull? (Or what length of rubber and how many steps?)
Sep 23, 2019, 10:05 PM
Keep looking up!
BirrenP's Avatar
It's a Wanderer 99. I think it weighs 46 ounces.


Quote:
Originally Posted by Bernd Brunner
what kind of sailplanes do you launch?


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