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Old Mar 19, 2014, 03:12 AM
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Originally Posted by quitcherbitchen View Post
Gave myself a scare turning onto final with half flap. She shuddered her wing like she wanted to tip stall. I was turning way too hot for flaps to be on. I guess more of an accelerated tip stall. I saw it happening and straightened out.
disclaimer: Ive yet to fly my stuka. But my brother saw the stuka and immediately said: there is no way thats not going to tip stall. His advice: differential rolls (up only) when flaps are deployed. Sounds like a good idea, I know this is done in some full size gliders. Im just breaking my head how to program this is my tx (Er9x firmware). Ive done differential ailerons before, but how do I make the differential setting conditional to the flap settings?

Also, when mounting the gear, I noticed it has a fair amount of negative camber. Not sure camber is the right word, like V shaped, less narrow at the ground then at the wings. Anyone else have that? Should I worry about that?

BTW, I have to admit, there isnt much room in this stuka to mount a sound system. There is a fair amount of foam that could be cut out to make room, but it wouldnt be trivial. Probably keep this for a future larger bird.
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Old Mar 19, 2014, 09:05 AM
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United States, CA, La Caņada Flintridge
Joined Jul 2011
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Put washers under the heads of the landing gear screws to straighten the camber/toe in issue of the landing gear. I think there are pictures in this thread showing it. The washers effectively shorten the screws and allow you to put pressure on the landing gear mount that straightens them.
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Old Mar 23, 2014, 05:25 PM
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Did a couple of flights with the stuka this weekend. Im pleasantly surprised how well it flies in general, although am I the only one who thinks the elevator is a bit underdimensioned? Its okay for scale flying, but I would like some more reserve. I already have it on the inner most hole, I cant get any more throw out of it, it just wont bend any further. Im considering gluing a piece of plastic on it or something to make it bigger. Has anyone tried anything like that?
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Old Mar 23, 2014, 09:40 PM
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Oh yeah, forgot to mention that when you start thinking you need elevator it is already too late. You have to think ahead with this plane. Actually, you can train yourself and later you don't even notice the elevator is so small.

Put a few batteries through mine today. Got inspired by you. She is still a joy to fly, but hard to land without a tip into the corner. I was 2/4 on that today. Dropped own of my Lipos too. dented the corner a little bit, but luckily didn't puncture it. Have to keep a eye on it next time I charge it.
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Old Mar 24, 2014, 05:16 AM
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Some footage of our flight yesterday. Most of it with my Mobius on the Stuka, and some shots showing my brother's spit (re)maiden.

Stukafire30 (6 min 18 sec)


Not the most impressive flying you will have seen here, keep in mind Im a noob with barely one or two hours fixed wing experience (on the pioneer) this century and a few more in the previous millennium with gliders. To me this plane is fast, and I need to adjust a bit .
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Old Mar 26, 2014, 05:05 AM
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Public service announcement #1

The stock sticky tape is no good, glue the cowling of your stuka, or this may happen:
stukacrashmp4 (1 min 13 sec)


(and yeah I botched that landing badly, I had no idea what was happening and didnt dare to apply more throttle)

Also note that a new cowling almost costs as much as an entire fuselage. I dont often think HK prices are exaggerated, but this one is .

public service announcement #2

Especially if you fly with straps, configure a safety switch/throttle hold on your tx. Or this may happen:

This is why you need a safety switch on the throttle (0 min 22 sec)
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Old Mar 26, 2014, 08:08 AM
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No luck. That Spitfire into the bike is crazy. Like what were the odds. I have had the throttle go off because the strap. The radio slips down on your stomach and hits the throttle. I switched to a tray and also have a safety switch. The tray cost less then $10.00, but the Diamond harness are expensive $39.00. Way cheaper then an Esprit harness though.
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Old Mar 26, 2014, 09:20 AM
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Like what were the odds. .
Not too mention the odds of my plane being parked at the other side and capturing it on video. I have to admit I did find it a bit funny, you couldnt do it any better if you tried it on purpose.

Spit has been fixed meanwhile, no damage a hairdryer and some C4 couldnt repair. Even the retracts where okay, quite impressive after a bicycle rode over it.

Tray is something we consider, but a throttle switch is a must IMO. Coming from multirotors and being used to having to arm the motors (and props spinning slowly when armed), configuring a safety switch was about the first thing I did when I began with electro planes as it immediately felt very wrong to have motor armed instantly. Unfortunately, my brother's old futaba doesnt seem able to do that.

Anyway, is it just me or does the stuka really fly worse with those cannon's mounted? seemed more nervous around its yaw and pitch. Didnt quite expect that, and not entirely sure if its wasnt just more wind. Ill find out later .
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Old Mar 26, 2014, 09:41 AM
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I didn't think about the camera in the Stuka getting the other plane in the shot. Wow, that really makes it difficult to imagine the odds. What was the bike persons reaction?

I only flew it with the cannons once and crashed into a palm tree. Got stuck. Cannons disappeared on the crash. I didn't notice it flew different. I now fly with bomb racks out where the cannons were. Can't say it effected anything but the speed.
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Old Mar 27, 2014, 07:23 PM
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Stuka crosswind fail compilation:

crosswinds (2 min 23 sec)
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Old Mar 28, 2014, 10:10 AM
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With the gull wing she isn't particular to crosswinds. Needs a gyro on the rudder if that is your every day conditions.
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Old Mar 29, 2014, 06:02 PM
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Originally Posted by quitcherbitchen View Post
With the gull wing she isn't particular to crosswinds. Needs a gyro on the rudder if that is your every day conditions.
A gyro crossed my mind, but we found a better solution to crosswinds. No such thing as crosswinds on a concrete slab this big:

concrete heaven (3 min 39 sec)




well, except when taxiing.

I am still struggling somewhat with pitch control. I just dont have enough authority for landing, especially with full flaps I regularly find myself at maximum deflection and still unable to get the nose up for a decent flare, despite ~1/4-1/3 throttle and enough speed not to stall. I dont think its nose heavy, I already tried adding some ballast to the tail, to the point where in flight it felt tail heavy and balancing it on my fingers, Im fairly sure it was behind the 45mm mark. Still wasnt enough.

For the last flight we cut out a V in the hinges of the elevator so they bend less and there is less friction, and that seemed to make it somewhat better, but Im still wondering if it wouldnt make sense to glue some plastic to the elevator to make it bigger or something? Also, when I trim the plane in flight, upon landing the elevator is at a non trivial "up" angle. Is that proof of nose heavy, or could it be something else?

For the record: I did put a mobius cam on the nose and an fpv transmitter in the cockpit, but their combined weight is pretty minimal and cg is adjusted. I also had this issue when flying "clean".
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Last edited by Vertigo72; Mar 29, 2014 at 06:12 PM.
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Old Mar 29, 2014, 09:05 PM
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A mobius and FPV can be part of it. My Durafly A-1 hates to have the FPV gear in it. I have to fly at 3/4 throttle most of the time and even with flaps she gets shaky winged. The FPV gear weighs a total of 100 grams.
My Durafly Trojan can stand the FPV gear. Hardly notices it. Not sure about where the Stuka fits into this mix as I have never put the FPV in her, but I have attached an 808 to her. Flew fine. The true CG test is a high altitude dive. If the plane wants to dive deeper into the dive then initiated then it is nose heavy. If it wants to climb out of the dive with no elevator input at all then it is tail heavy.
One thing you can do to help your problem is to change your landing habit. This plane can tip stall so you can't let her bleed off too much speed. She can fly at a crawl mind you if you keep your inputs on the tame side and exercise the rudder Vs the ailerons. I typically cut the throttle and dive at the runway until I see the Iron Crosses on the top of the wing and then with room-- pull out and just float down the runway about 6" off the ground until she settles. This technique has never failed me. With full flaps on it is very controlled. I modified my flaps to even move the insides. She dives incredibly slow with this mod. Granted I don't have cameras and FPV aboard. I also learned from others to use opposite aileron if she tries to tip onto a wing. In other words. turn into the direction of the tip.
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Old Mar 30, 2014, 04:16 AM
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thx for the long reply.

Im pretty sure about the cg, I did the dive test and 60-90 degree bank test, and it seemed fine to me, almost no nose drop, nor pitching up. I might doubt my own judgement but a friend with 40 years RC (and RL) flying experience and he came to same conclusion I did ( he is the one who took an exacto knife to the elevator hinges after being unable to flare without adding lots of throttle). He said cg was neutral to marginally nose heavy, but that was before we added lead to the tail, which made it a tad tail heavy.

You may be right about the weight. Though a mobius weighs 38 gr and the transmitter 23gr. Thats really not a lot. But hey, I may as well try again without and see what happens, I know I had this issue before I put anything on it, but perhaps not quite as bad as it was yesterday. Meanwhile I used some carbon strips to reinforced the fuselage , which seemed to bend far too easily (especially the rear part and at the wings). Doubt its related, but shouldnt hurt

Just one quick question: if you look at your elevator, stick neutral (and assuming its trimmed), does it point upwards or is it about level with the horizontal stabilizer? Mine points upwards Im guessing 15, maybe 20 degree (with no thrust, I do have a mix on it that pushes it down to 5 ? degree or so upward deflection when full throttle)
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Old Mar 30, 2014, 06:25 PM
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It flew fine today. Not sure what cured it exactly, but between rebalancing it, opening the elevator hinge further and reinforcing the fuselage, I had no problems today. Well I did, but not related to elevator.

First of all, there is no way I can keep the wingtips from hitting concrete after landing. I have made countless bad, mediocre and picture perfect landings, and seconds after touch down, I will drag one, then the other wingtip over concrete and look like an idiot. A friend of mine was making fun of me, so I handed him my transmitter. He is a national rc champion (DLG) and really knows how to fly, he couldnt avoid it either. Not sure if its the fact its top heavy, angle of landing gear or something else, but its mildly annoying. Im going to have to put some plastic reinforcements on the wing and aileron tips, or I will decrease my wingspan a few cm per day!

THe second thing is when doing loops. When I pull out of the loop it will always turn right. First I thought it was a torque thing, but trying various throttle settings didnt change much. Slightly baffled by it.

Lastly, not really a problem but it spins.. really well. Even when I didnt quite expect it. I did some stall tests and it seemed fairly docile, but when I slightly botched a wing over it promptly went in to a furious spin, and didnt recover until it pushed the elevator down. Close call there, I wasnt quite expecting that.
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