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Versa Wing teething issues

#1
Hello! I've been flying since 1993 and I've returned to the hobby and to electric flight after several years. I've just finished a Versa for combat in my club and this morning went to maiden it and it will not fly. The plane nose dives into the ground. SETUP: pusher setup with the beef electric package, mounted the essentials motor mount to the bottom of the wing through a cutout in the top of the wing, prop is 90 degrees to the wing bottom. Lipo mounted in the nose as far forward as practical which needed 3 1/2 oz's to balance at the recommended point, it sits level with a very slight nose down attitude.
The Launch: Gave some up trim on elevators, set throttle about half to 3/4's and tossed it with a discus style throw very slightly nose up and it immediately dove as though it had full down elevator. I checked everything again including balance and tried again with the same result. I removed 1 ounce from the nose with the same result. I took out another ounce with no change. My planes always fly, including a crack wing that I recently built which basically flew out of my hand. Am I going the wrong way with the nose weight? I'm at a loss here. Thank you all in advance!
 

makattack

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#2
Hello, and welcome to the Flite Test World! Sorry to hear of your problems, but did you build the Blunt Nose version of the Versa or the older "Arrow" version? The CG point moved on the blunt nose version a bit more forward, I believe. Both versions I've built, with a 55g motor in the back (pusher like yours) and a 2200mAh battery at the nose require about 100-150g of nose weight which I think works out similar to yours.

My guess is that although you stated you trimmed your tx with some up elevator, you might want to instead dial in some mechanical up elevator/reflex. All my builds have had I think between 12-15 degree up elevator mechanically dialed in. With that, they launch easily and fly level with no elevator input on the TX. I even cut out a deflection guide for the versa with some scrap foamboard to make it easier for me on builds and pre-flight checks. I put it on the top/flat surface of the wing, at the hinge line to the elevons, nearest the motor, and the elevons just touch the angled portion which is 12-15 degrees (the FT build plans state what the recommended reflex is, I believe).

Other than that, the only thing that comes to mind is maybe the launch style. I've seen a lot of discus launch attempts go bad if there's over-rotation at the launch point. I personally prefer the overhead launch technique as it's far more reliable and easy to perform for me. Never had a nose in crash at launch with that technique for me.
 
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Craftydan

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#3
Hey Yellowbusguy!

It sounds like the wing is stalling, but hard to say for sure. The versa can be a fairly heavy wing, so it needs a good bit of oomph to get going.

Have you tried a glide test -- It should glide very well for a turbulated wing. When trimmed my versa would float a good distance on a hard level toss -- plenty enough to throttle up mid-glide.
 

makattack

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#4
Hey Yellowbusguy!

It sounds like the wing is stalling, but hard to say for sure. The versa can be a fairly heavy wing, so it needs a good bit of oomph to get going.

Have you tried a glide test -- It should glide very well for a turbulated wing. When trimmed my versa would float a good distance on a hard level toss -- plenty enough to throttle up mid-glide.
That's another possibility. Yeah, on my heavier blunt nose versa (I use elmers foamboard for the center section and the wing tip plates) -- I need to make sure I give it a big, strong toss. Even at 75% throttle. I sometimes up it to 80-90% and dial it down after it gains a bit of altitude.

I have had a few weak tosses or not enough throttle, but the wing just glides down as if coming in for a landing. I've never had it nose in hard on launch. On my first Versa Wing, I was coming in for a landing, had max elevator, and it was still about 2-3 ft off the ground, but the throttle was zero, and I definitely stalled it. It tip-stalled hard. One of the wings dropped and it landed upside down, nose down. I would think a launch powered stall would be similar...
 
#5
It behaves like a lawn dart, I don't think stalling is the issue, I have not attempted to glide test it. My all up ready to fly weight was 1lb, 10 oz's. This is really puzzling, though I am new to wings, this is the standard pointy nosed model.
 

makattack

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#6
It behaves like a lawn dart, I don't think stalling is the issue, I have not attempted to glide test it. My all up ready to fly weight was 1lb, 10 oz's. This is really puzzling, though I am new to wings, this is the standard pointy nosed model.
Ahh... if you're new to flying wings... when I was setting up my first wing, I had to look up how to mount the prop and setup the motor for pusher operation.

I would check two things:
1) The prop should be mounted similar to a tractor pull motor: letters towards front.
2) The motor needs to spin it clockwise if you're looking at the rear of the prop.

It might sound too obvious, but I'd also check the control surfaces. If this is your first time with a flying wing and elevon mixing, you will want to carefully check that the control surfaces are behaving as you expect. Do the "High Five" test that the flite test folks demonstrated, or just check to make sure as you pull back on the elevator, BOTH elevons go up to reach for the sky. When you push forward on the elevator stick, the elevons both go down. Left aileron, the left elevon goes up, the right elevon goes down. etc.

Also check the surfaces when you pull left or right elevon with some elevator mixed in...
 
#7
New to wings but not my first one. I have a Twisted Hobbys Crack Wing that I've built and currently fly as often as I can so I am familiar with the particulars of wing setup. It just didn't "feel" right before I attempted to fly it. It isn't damaged, just my pride. It should fly, even though it's heavy, I've read where some FPV variants weigh into the 800 gram range and mine is around 750.
 

Craftydan

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#8
Yeah, it 750g is on the heavy side, but not unbearably so . . . should still glide fine.

Stupid question you've probably answered . . . how much reflex did you put in?
 
#9
I added up trim on the elevator. Someone said something about 12 degrees of "reflex" which I think is being confused with 12 Degrees of control surface deflection as called out by the specs. This is my low rate setting, and high rates I've set at approximately 20 with 35 % expo on each. If the wind calms down this evening, I'm going to see if it will glide at all from the deck. This is really frustrating, it's the first plane of mine that wouldn't fly. It's way too heavy.
 
#10
If it does glide but noses in with power applied you probably have a thrust line issue.
With the motor sitting above the wing the thrust it generates will want to push the nose down. putting some shims under the bottom mounting screws would held remedy the issue if I'm not mistaken.
 
#11
I had considered that. While checking the set up again for correct throws I was holding it nose down on a chair and when I'd run the power up the back of the plane would try and rotate upward (if it were horizontal). In flight I could see where this would push the nose down. I'm glide testing it today assuming it does storm again. Thanks!
 
#12
Oh...I have the same problem with the Blunt nose Versa but I thought it's because something's wrong with the CG. I've removed half the wait from the front and standing by for good weather to try it. But looking at your post it seems something else is eluding me/us. Please let us know if/how this goes.
 

MT Alex

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#13
I added up trim on the elevator. Someone said something about 12 degrees of "reflex" which I think is being confused with 12 Degrees of control surface deflection as called out by the specs.
Nope, no confusion, you have to have around 12 degrees of up elevator mechanically trimmed in if you don't want your versa to lawn dart on launch, he was not talking about throw deflection for flight. TX trimming won't cut it. I completely ruined my first versa with this issue, and ended up giving up on it. Then I built a blunt nose version, and almost ruined it, as well. Finally, I read some posts here, and referred back to Bixler's build video and found my issue. When you are setting up your control surfaces, you need at least a quarter of an inch between your straight edge and the hinge joint of your elevons. My gap is closer to 3/8. Here's what my Versa looks like with the TX on and the servos centered.

IMG_20140625_093908_053.jpg
 
#14
I had that much elevator trim in it when I first tried to fly it and it dove uncontrollably. An earlier post suggested a thrust line issue if a glide test was successful. I did a glide test this morning and it did what it was supposed to do and had a predictable glide, which I repeated twice. So now the thrust line looked to be the real problem so I shimmed the bottom of the motor mount with washers and now it flies right out of my hand. Made two drama free flights today until it got too windy. Try this test: Power up the plane and place it nose first on a chair cushion or the floor and hold the plane vertically. Apply throttle and see if it wants to tilt in the pitch axis with power on. Mine did before shimming the motor and now it shows no tendency to change pitch. Bob
 
#15
You were correct with the thrust line diagnosis. The glide test went well so I added washers (2 each side) till the pitch tendency under power disappeared. I flew it today on two drama free flights. Flies right out of my hand at half throttle. Thank you so much for the suggestion! Bob
 
#16
You were correct with the thrust line diagnosis. The glide test went well so I added washers (2 each side) till the pitch tendency under power disappeared. I flew it today on two drama free flights. Flies right out of my hand at half throttle. Thank you so much for the suggestion! Bob
Yay me! (just kidding!)

Glad you got your problem sorted out. My last pusher plane developed similar symptoms after swapping the engine, not quite as severe, though, since it wasn't a wing.
I've since stopped flying pushers because their inherent noise emissions makes it hard to stay "under the radar" in crowded southern germany.
Too bad we're a Nation of complainers...

*notices the subtle irony in that last statement of his*
I'll shut up now.
 
#17
The idea that an electric plane is too loud is amazing, although this Versa isn't very quiet is it? Reminds me of a Cox .049 black widow in the way it sounds. Thanks again for the suggestion. I think I can pull more weight out of the nose to improve pitch sensitivity, which is rather poor at the moment. It rolls very well though. I'm going out again tomorrow evening and try to catch some calm air and make a careful evaluation of it's flight character and do some tuning. It's been good talking to you and feel free to contact me anytime. Bob Louisville Kentucky USA
 
#19
The idea that an electric plane is too loud is amazing, although this Versa isn't very quiet is it?
Well, it didn't seem too loud until after a high-speed pass followed by a low-throttle climb into a turn maneuver. The echo thrown back from the woods next to the field made me think there was another guy flying close by.
Decided to better be safe than sorry, switched to larger props and tractor planes.
Still able to do 70+mph passes, just without the noise
 

makattack

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#20
Nice to hear you found the solution! I would have never suspected a thrustline issue. All my Versa builds have had the motor parallel with the bottom of the airfoil, with the prop pretty much perpendicular, so I don't have any up thrust. I just rebuilt my versa after sending the last version into a Pond (beginner at FPV, and discovered that 5.8GHz does indeed have trouble penetrating trees) so I'll have to check to see how this one flies.