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Old Jul 24, 2012, 01:12 PM
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FLY F3B's Avatar
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Ian, that is really REALLY sexy. Super nice. Hope it goes well for ya.

Mike
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Old Jul 25, 2012, 09:35 PM
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Ian thats great dude! Can't wait to see it go.

K
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Old Jul 28, 2012, 06:54 AM
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Joined Dec 2009
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Hi all
Fosa Lift No2 is on the stand (maiden tomorrow)
C/G 106mm
AUW 2250g
Fosa Lift No1
C/G 106mm
AUW 2240g
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Old Jul 29, 2012, 04:26 AM
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Now thats just greedy . . 2 fosa's
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Old Aug 01, 2012, 05:43 PM
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Hi All

Maybe someone has an idea, what i'm doing wrong with my fosa lift setup.

At the moment my plane has a distinct spiral tendency in thermal turns. Wich means it is only possible to turn it really flat or fly it faster than ussually in thermals.

First idea was, that my C/G is wrong, but i measured it several times and result was everytime 105mm. I also tried to move C/G +/- ..3mm but that didn't solved the problems.

My next idea is now, that i fly with to big throws on elevator. Maybe someone can post his elevator throws? Cause i can't find any throws for elevator in this thread.

I'm also appreciate for every other idea, what i'm doing wrong.

Thanks
Pascal
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Old Aug 01, 2012, 06:15 PM
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Pascal, how much experience do you have flying F3B type models? This will help in the discussion and incoming advice.

Mike
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Old Aug 02, 2012, 02:02 AM
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Originally Posted by FLY F3B View Post
Pascal, how much experience do you have flying F3B type models? This will help in the discussion and incoming advice.

Mike
Hey Mike

I startet to fly F3J/F3K planes ~6 years ago. And bought my first F3B plane (a Tragi 703...) ~4 years ago and fly this one till now (wich means the fosa is my second F3B plane...i know, thats a huge step from a Tragi to the fosa). I have no experience with V-tails, which is maybe a problem. (Cause i can normally do a basic setup on a X-tail by view...but there's no chance for me to do that on a V-tail...).

I measured my throws wich are at the moment +/-8mm for elevator and +/-12mm for rudder (measured on  fuselage side). So maybe someone with V-tail experience can tell me if that looks normal for a fosa?

Thanks
Pascal
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Old Aug 02, 2012, 02:49 AM
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7 or 8 mm is pretty normal for a v tail elevator, although I tend to use less, especially in speed.

The tragi 703 is more like a J model I would suggest. The 704 is the one more designed for speed, although it is slow in comparison to modern models. Certainly my 704 cross tail is an easy handling model.

The Fosa lift seems to thermal well from what I have seen.
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Old Aug 02, 2012, 06:15 AM
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I've had to back off my elevator throws on a Baudis Models Cyril F3F to prevent it doing the dreaded spiral death dive. I don't fly F3B so don't know how much elevator you need, but for F3F I have it backed off so that I hit the stops in the turns to stop putting too much elevator in. Will measure it later today if the weather plays ball and I get out after work up the slopes and post back for you to give an idea.

Cheers

Tom
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Old Aug 02, 2012, 01:18 PM
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FLY F3B's Avatar
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Thanks Pascal,

From your description and what you've told me, I would not focus on the elevator throw other than to say that you must be careful not to hold too much and over-slow the glider in a thermal turn. Fosa's and other high end F3B models do thermal very well, but you have to be careful of slowing them too much. What you end up with is a stall, and the resulting 1/4 turn spin. But this isn't what you are asking about I suspect.

For normal thermal circling, some guys tend to hold rudder into the turn without regard for what the glider might really need. Do you like to hold some rudder input in the direction of the turn? If so, this is most likely your main problem. As with all sailplanes with fairly flat wings, (no 7 degree polyhedral joiners for the tips) one must be aware that corrections with opposite aileron to maintain the wing bank and keep it from getting steeper is normal operating proceedure. In fact the more rudder you use to fly a slower, coordinated circle the more you will be using your aileron stick to keep the wings at the proper bank angle, and not over bank and start the spiral.

Let me know if what I am talking about is on target or not?

Good luck.

Mike
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Old Aug 02, 2012, 05:58 PM
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Hi all

@satinet
Thanks alot for your inputs about the Tragi (...and also for confirm the throws...). You described that the Tragi 703 is more like a J model. Wich means for me, that i have to fly the fosa normally faster than the Tragi.
If the weather looks okay i will try that at the weekend.

@Tom
Thanks for your interessting input. I hope to get the weather at the weekend to try smaller throws.

@Mike
Thanks for your detailed descriptions.
I read out the logfiles from my radio and analysed them with a special focus on the aileron/rudder movements.
In the logfiles it looks like i use the rudder normally only as a slave function for the aileron (...means same direction as the ailerons and only have rudder movement when i have to use the ailerons...). I will try at weekend to use the rudder more for turn coordination.
Details and if it works after the weekend...

Cheers
Pascal
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Old Aug 05, 2012, 01:57 PM
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Went out to the field today...a paper with notes what i have to try with me...an came back with a big smile in the evening

Steps in the right direction:
- back off the elevator throws -> feels better for me with less elevator throw (~6mm now)
- rudder differential -> found out that the nose normally goes up a litte bit when i use rudder (...wich means the plane slows down)
- aileron differential -> less differential and a little aileron->rudder mix...as i learned in the "differential phobia" Topic...

With those setting i feel now really confortable with the fosa and had no more stall or turn spin and was able to catch the thermals.

@Mike
You explained me a hole route to the target. I think i made the first steps on this route today, but it's really hard to change such habbits. I'm confident that it's possible to raise my skills with your hint.

Thanks to all for the hints and ideas.

Attached some pictures from the flights.

Pascal
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Old Aug 05, 2012, 06:04 PM
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FLY F3B's Avatar
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Great news Pascal. Experience flying these models pays back very big in skills development. If/when you learn to fly this FOSA well, you will have the skills to fly nearly all RC gliders very well. TD and F3J models will seem extraordinarily easy to fly, DLG's will be crazy easy to fly and fly well. Remember also that as with all glider flight the speed you fly should be dependant on the air mass that you are flying in. General rules: When in lift, circle a slowest comfortable manuevering speed with thermal camber. When searching, or cruising, fly faster, in normal (uncambered section) and if sink is encountered, speed up even more. You don't want to spend any extra time in an area of sinking air.

Enjoy your F3B glider. To me there is no other type of glider that is this much fun to fly.

Cheers.

Mike Smith
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Old Aug 24, 2012, 02:20 PM
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I will be maidening the fosa lift today, thanks to Alvaro for the build out, CG at 106 just need wind. Ian
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Old Aug 24, 2012, 03:47 PM
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Picked up my New Fosa Lift, from Warren who is awsome to go pick it up for me. It has two carbon wing joiners that are tight, the finish of the plane is really good and the fit of the wing to fuse is super tight, can't wait to ring this one out.Thanks also to Bob at Soaring USA for the plane. Ian
Nice colors Ian

Man you really arm your fleet
Cheers
Thomas

PS. I don't think the F lift needs much wind,
CU at SU?
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