Red Eagle flying wing

[lobstermash]

Just finished putting together my new (from HK of course) Red Eagle EPP wing. $20 is an amazing price, but EMS is a the only postage option. Still, $36 to my door in 3 days isn't too shabby.

This thing took way longer to build than I expected... But it seems pretty solid. My only gripe (and longest process to remedy) was the canopy... I don't have any micro receivers, so fitting my 9x rx, along with 20A ESC and 1000mAh battery in the standard canopy was impossible. This meant getting out the scalpal and carving a piece of EPS (the only decent foam I have) an extension to the canopy, and building in a hatch.

Anyhow, the plane is now ready to maiden. I'll attach a couple of pics of the canopy for those interested.

 

[lobstermash]

The battery just fits in on top of the ESC and I used a rare earth magnet to hold the canopy down. For easy removal I put a control horn in the middle.

COG is about 144mm from the tip of the nose. Powerplant is a 2208 1400kv (pinched from the HK Tuff Trainer), spinning a 7x6 APC style prop. I haven't maidened her yet, and am a little nervous given this is my first wing and I'm scared of that prop...

For those who haven't done it before (this was my first time), programming elevons on the 9x is really simple. Just plug one servo into channel 1 and another into channel 3 (mode 1) and activate elevons through the menu, setting the appropriate level of movement (100 here, -100 there...) until the control surfaces do what they're supposed to.

 

[colorex]

What material is it? To me it looks a bit flimsy...

 

[lobstermash]

The wing itself is pretty solid EPP, reinforced with two carbon fibre rods and two carbon fibre strips. Ideally the canopy extension would be EPP, but I don't have any spare. It sits on top of the plane anyway, so *shouldn't* come in contact with the ground too often...

 

[colorex]

Well, then it shouldn't be flimsy.

Have a nice flight.

 

[lobstermash]

Thanks, maidened in about 15km/h wind. The thing tried to jump out of my hand, so I lowered the throttle a little and tossed it. Not quick enough to get onto the controls, so gently floated down onto the grass. The prop took a little bit of foam out on landing (prop-saver). Take two, with a little more oomph and quicker onto the sticks, and it was up! Flying around at 1/3 throttle, I did a few circuits and tried to trim it out. Needed a little up elevator. It was flying nice, so I upped the throttle to about 2/3. Too much without knowing the plane. Tried to recover from a sudden case of dumb thumbs and it nosed into the ground. The battery busted out the nose. Half an hour later, the plane looks like new again. But I'm dangerously low on glue.

 

[colorex]

[ ]

 

[lobstermash]

Yeah, I bought two tubes of the stuff on my last order. One of my trainees forgot to order some with his Bixler kit, so I gave the second one to him... The other tube has about 1 minor repair left in it, after finishing off the predator and building this wing. The equivalent product at local stores is about $9-10! *boycott*

 

[colorex]

I will order this with my Bixler. Thanks for the reminder!

 

[ananas1301]

I will order this with my Bixler. Thanks for the reminder!

Glue is a must have!! If you don´t have it, it will make many things much slower and you´ll have to much much longer for the next flight.

Anyway nice that your wing flies nice. For you first wing it looks so much like a speedwing!

 

[lobstermash]

Yeah, had a couple more flights yesterday evening. I'm having trouble launching the thing because it's not trimmed out, so I have to be super quick onto the sticks and it takes a little while to get it settled in. I think I need someone else to hand launch it for me. And practice flying a wing on Phoenix. It's a shame you can't simulate launching though. Flying's not the bit I need practice at

 

[ananas1301]

Why do you need to be quick on your hands?

The easiest way to do it is simply holding the left leading eadge of the wing in your left hand and the TX with your right hand right on the sticks you´ll need for takeoff
Then with your mouth push the throtle stick up so that you feel the push to be enough to fly and let the plane go.

Also trimming out properly makes it a lot easier but it should still be possible.

 

[lobstermash]

I fly mode 1 (throttle on right). You have to be quick to get back on the sticks because it starts to roll slowly after you toss it. I toss it right handed with my thumb on the elevator. I've set the rudder (left stick) to operate the ailerons as well now, so that should make those few seconds after tossing slightly easier. I launch with my right hand.

 

[lobstermash]

Discovered a twitchy servo... Replacing that might help too

 

[lobstermash]

OK, help please if you can... I've got the hand launch thing down pat. I was flying in about 17-20km/h wind, the plane is on the recommended CoG, I flew a couple of circuits without trouble, then the wind picked up a little. Then, the plane starts to nose down across the wind from about 15m up. I didn't cut the throttle straight away (I cut it just off the ground), but was holding full up elevator to no avail. I just started to pull up just off the ground, landing hard just aft the nose. What the?!? Full up elevator. Anyway, the plane is now repaired and ready to fly again.

Has anyone else experienced a similar issue with this/other wings/planes? How do I fix it???

 

[lobstermash]

Nobody? My only thought is perhaps the gap between the wing and control surfaces is too large... Got about 1.5mm because of the hinges. Perhaps I could try taping the top edge...

 

[ananas1301]

Nobody? My only thought is perhaps the gap between the wing and control surfaces is too large... Got about 1.5mm because of the hinges. Perhaps I could try taping the top edge...

That is a issue but I don´t think it is that much effective on this case.

What you should rather do is look how strong your servos are and also just for once for a try push with with your finger on the control surface (which at that moment you´re pushing is gonna be lifted up (so youüre giving constant up elevator)) and then look if it is very easy to push down. Because if you´re flying against the wind. + your own speed you might be flying 40 kmh which acts with a lot of pressure on the control surfaces.

Also pinpoint the far sides of the control surfaces. You might need to stiffen up the control surfaces for that case.

 

[lobstermash]

My servos are 10g and 1.6kg torque, so I don't think it's that... I've got 20mm hinges along the control surface and a carbon rod the length of each one. But just to check I'll get a fan and see how the air acts on the surfaces.

I also found this, which makes me think more about how large the gap is. The responsiveness is worse the further I pull the stick down, which is consistent with the physics described in the article.
http://www.3dvision.com/wordpress/index.php/2011/08/27/model-aircraft-control-surface-spacing-and-solidworks-flow-simulation/

 

[lobstermash]

Alrighty, thought I should post a follow up on this thing. I was having a lot of issues initially. When I fixed the gap, it took a lot of elevator trim to get it to fly level. I also had serious stall issues, whereby for no apparent reason it'd spiral out of the sky. To top it off, it wasn't stiff enough, so it'd shudder when it sped up.

So, for those who are tempted into getting one of these (and they're very tempting because of the price and very low shipping weight):
a) you need to add more foam to the canopy walls to fit your radio gear;
b) make sure you hinge the elevons in really close;
c) pack the carbon rods in with hot glue to make it as stiff as possible; and
d) try and get the cg around 140mm from the tip of the nose, not 148, not 145, maybe 143 is acceptable.

Now that I've sorted the stall issue, this is a brilliant slope soarer. I also spend a bit of time putting it high in the air and gliding it down. It doesn't need much wing to lift it.

My settled power system is a 2205 1400kv, an 18-20A HK ESC, Turnigy 1000mAh 3s, 8x3.8 prop (cut down to 7.5x3.8) and two Turnigy 9g servos. I get around 10 minutes of 3/4 to full throttle flights or more if I'm sparing with the throttle

 

[ananas1301]

Glad you got to Fly Vetter tuen initially.

With Wings the cg is offen an issue because you Need to get it As far to the Front As possible Most of the Time.