My versa is... wiggly. Help?

[AeroMaestro]

I just finished my Blunt-nosed Versa and had the first flight tonight. This is my very first home-build, so I learned a lot in the process. (I'm definitely not new to flying -- just new to building.)

Anyway, the Versa flies great, except that it... "wiggles" through the air. It's constantly yawing back and forth; it looks a little bit like an excited puppy. This happens whether I'm gliding or powered.

Any suggestions on what I need to do to fix this? Possible problems that I'm considering -- but again, I've never homebuilt before, so I'm not sure which to test first.

1. Maybe it's an aerodynamic problem? I've mounted two cameras up front, side by side: my board cam and my mobius. The board cam's mounted on a FT Elements firewall, and therefore sticks up in the wind more.

2. Maybe the wing tips aren't straight? I'm not exactly sure how to check.

3. Possibly still tail heavy? I added an extra 2200 mAh 2s battery up front to balance it out using the marker holes on the blunt-nose body. It's almost perfect, but maybe it's just a hair heavy toward the back. I didn't have any stability or flight-characteristic problems (apart from the weird wiggly yaw) that would make me think it was tail heavy, but this is my first wing and I'm used to more conventional planes.

I tossed a quick 30-second youtube video up of the onboard mobius from the maiden. You can pretty clearly see the wiggly-waggly yawing here, both gliding and powered.

And here's a photo:
http://gfycat.com/OldIndolentHarborseal

 

[earthsciteach]

Welcome to the forum! First question - do you have winglets on the wingtips?

 

[AeroMaestro]

Welcome to the forum! First question - do you have winglets on the wingtips?

Yup. Sorry, it looks like my .gif photo ended up as a link instead of a pic.

Here's a quick shot of my versa

 

[xuzme720]

I get a little of that on mine also. Doesn't seem as much as yours but mostly notice it coming out of turns. It might just be inherent to the airframe but if it's really bugging you, make sure the tips are parallel with each other. I noticed my wiggle was worse when one of my tips pulled partway off and was angled out in front...

 

[earthsciteach]

I have built flying wings that behaved as you describe, but those didn't have winglets. The cameras are so close to the centerline that I can't imagine they would cause a yawing effect as you describe.

The yawing appeared to occur when it was at low speeds in the video. Perhaps you were close to stall. Does it yaw when at higher speeds under throttle?

 

[makattack]

I find my Blunt Nose Versa yaws a lot in windy conditions, especially when flying or turning with a crosswind. If it's calm, it flies and turns smoothly. I believe that's the nature of flying wings. I think some people have put bigger wingtip plates or even added vertical stabilizers where the swept wing joins the blunt nose to reduce this adverse yaw / waggle.

Here's my example video, filmed over two days. The first day, it was dead calm, but I had a bum TX that caused the RX to go into failsafe with a lost handshake. For some reason, I thought a great failsafe would be to cut throttle, and pull a hard left aileron roll.

The second day, it was windier but I used a different TX that gave me better range. Not much yawing on the first day, but more on the second windier day.

https://www.youtube.com/watch?v=_m1YERPxs4U

 

[AeroMaestro]

The yawing appeared to occur when it was at low speeds in the video. Perhaps you were close to stall. Does it yaw when at higher speeds under throttle?

It's definitely easier to see the yawing in this video when I'm flying slowly. I flew about 11 minutes at mostly 50% throttle. It yawed the whole time. But if you think the waggling is an indication of a near stall, then perhaps I could improve it with more weight up front?

 

[xuzme720]

I would give that a try. Does it seem overly sensitive? that's another good indication the CG is almost too far back...

 

[AeroMaestro]

I find my Blunt Nose Versa yaws a lot in windy conditions, especially when flying or turning with a crosswind. If it's calm, it flies and turns smoothly. I believe that's the nature of flying wings.

I added another 70 grams of nose weight and it's helping. (That's roughly 300 grams of weight added up front, including the Mobius, FPV camera, video transmitter, and three 70 gram lead fishing weights. (In addition to the 2250 mAh 3s battery!))

I flew twice more today and yes, it's definitely better when there's no wind. This is the largest and heaviest plane I've flown, so I guess I'm a bit disappointed it doesn't handle the wind better. Or perhaps the solution is to find myself a bigger flying field and just go full-throttle all day. With the big ol' Suppo motor on the back, this thing is a rocket at full-throttle, even though I've got a Slo-Fly prop on there since I'm too lazy to buy the proper blades.

Since I put LEDs all the way through the body it lights up very well at night, so I guess this wing will be my night-flyer when it's dead calm out. Maybe it's time to try out some late-night FPV.

 

[AeroMaestro]

Here's a quick video from last night -- it's flying pretty smoothly when the sun has set and the wind has quit. I'm still flying line-of-sight. I haven't gotten quite comfortable enough with this plane and this field to try FPV yet, even though all the gear is installed.

 

[Tactical Ex]

Looks like the weight helped but if you want to try some more options you could drill down on the winglets. I usually burn through them fast enough to not care but I noticed the wiggle reduced by a lot on one of my first ever planes when I added a double bevel to the winglets (which were also about 2x taller than the stock design) so they were blade like. Also, make sure they are perfectly aligned by measuring from the front of one winglet tip to the front of the other and from the back of one to the other. Rip the winglets off and shave the wingtip down until they are parallel (obviously they need to line up parallel to the center cord or you will have some unwanted strafing).

 

[makattack]

Glad to hear you've been able to experience calm wind flying. Yeah, the Versa absolutely loves calm conditions, and I love flying it in those conditions. I started down the road of implementing this:
http://plane.ardupilot.com/wiki/differential-spoilers/

to get better yaw control and add speed brakes on this wing, but I realized I'd have to modify my electronics to deal with the added power load (was planning on using digital micro servos) along with the added weight and complexity.

I still plan to put the APM in it, just for RTL and other safety aspects when flying FPV (telemetry, etc) -- but, just to warn you about FPV night flying. Unless you get a camera with good low light conditions, there's no amount of lighting you can easily and inexpensively put on your Versa to be able to fly FPV without an APM/OSD combination that will allow you to fly IFR (instrument flight rules).

 

[AeroMaestro]

Differential spoilers -- very cool.

 

[SteevyT]

Glad to hear you've been able to experience calm wind flying. Yeah, the Versa absolutely loves calm conditions, and I love flying it in those conditions. I started down the road of implementing this:
http://plane.ardupilot.com/wiki/differential-spoilers/

to get better yaw control and add speed brakes on this wing, but I realized I'd have to modify my electronics to deal with the added power load (was planning on using digital micro servos) along with the added weight and complexity.

I still plan to put the APM in it, just for RTL and other safety aspects when flying FPV (telemetry, etc) -- but, just to warn you about FPV night flying. Unless you get a camera with good low light conditions, there's no amount of lighting you can easily and inexpensively put on your Versa to be able to fly FPV without an APM/OSD combination that will allow you to fly IFR (instrument flight rules).

I've been toying with the idea of doing something similar to differential spoilers. However, my idea involved kicking the winglet on the side I want to turn toward outward rather than cutting the control surface in half. Still takes two extra servos, but it seems like it would be easier to set up.