Originally Posted by Tom Frank

Thought I'd post some pics and video of my 56 in. eagle build since I made a few mods that might be of interest. I wanted to make the airframe a little more "bird-like". The mains mods are:

1. The "wrist" break in the wing LE was moved inward and the tip feathers extended slightly to more closely match eagle pictures I saw online.

2. The wing tips were bent up in a smooth arc with a hair dryer rather than a sharp polyhedral break.

3. The tail feathers were lowered into the body by about 3/4 in., and slightly reshaped wider at the front with a straighter line going aft, again to more closely resemble a real eagle. This also allowed the pushrods to the tail feathers to exit the top of the body where they aren't as visible.

4. The beak width was made about 3/4 in. narrower, again for a little more "scale" look.

5. I wanted aileron control, but again striving for more bird-like qualities, I contrived what I call "warperons", which are flexible ailerons with the outer end left attached and not cut free from the main wing. So when activated, the warperon actually twists into a gentle curve, with full deflection at the root and no deflection at the tip! This mimics the action of a real bird wing in flight, and is made possible with the soft foam board used in the construction (I used Elmers foam board for the wings). I did some tests and calculations to confirm the force required to deflect the warperons only uses about 1/4 the torque available from the HXT900 servos driving them, including flight loads.

6. The wing was reinforced with two strips (top and bottom) of 12K CF tow, epoxied into very shallow "trenches" in the foam for more strength. I also extended the body side doublers all the way back to the wing TE for more strength and rigidity. The wing was secured in place with extra plastic wing securement hardware left over from my GWS P-40 (doubled pinned LE and double bolted TE). I plan to install a stripped-down JAZZ HDV178 camera in the belly of the bird for some AV flying later.

The power system is an SK 400XT outrunner from Hobby Lobby and a 1200-1300 mAh 3S lipo.

Following are some photos of the build showing these mods. Here is a video of the control surface set-up showing the warperon action. And finally, here is a video of the maiden flight, which was not without some drama All my planes must first prove airworthy before I bother to paint them, so my eagle was all white in these pics and videos. But it has now earned it's flight feathers, and will next be painted to look a little more realistic.

Great video.

If a plane climbs when you hit the throttle tipping the motor down will help to trim the functions. This helps not only with full throttle but also makes the throttle transition smooth and stable. My Q-Planes do the same thing and need about 9 degrees down thrust on the motor to have smooth throttle with out climbing or diving.

Since we have been trimming these a little more as though they were wings I wouldn't be surprised if it needs the motor angled down.

I really like the design!!!

Lee

Lee,

Your Peregrine was also one of my bird design choices... may do that one next... it's a great flying bird.

Yeah, I know about down thrust/right thrust and I did put in both on the firewall based on comments I read in this thread... just not enough. I couldn't find any comments on how much "more than normal" was! I've been using down elevator mixed to my throttle stick to accomplish the same thing... easier to tweak in different amounts to find the sweet spot. With this bird, I also need to counter the torque roll more... just not sure whether warperon action alone will do it best, or the V-tail rudder. The rudder action makes the plane both turn and dive, so maybe the V-tail alone will do it. I've only had the one flight, so more experimenting is needed.

Praymond,

This plane flies great on just the warperons and elevator... it will do nice gentle turns without losing any noticeable altitude with just the warperons alone. BUT, if you need to make a sharp turn... like I did in the maiden video as my plane banked left under power towards those trees... the rudder action really helps. It could also come in handy for evasive manuevers when you come under bird attack!

The warperon hinge line is fully cut and hinged with continuous "Z" hinges from root to tip... I just did not make the final cut to free the tip end of the aileron. The intent was if I didn't like the warperon action, I could cut the tip free and have full aileron deflection all the way out. I could get a much better roll rate that way of course, but I just wanted some roll control during landings and in flight. The warperons do that very well and seem to allow turns to be more flat, better for shooting aerial video and to look more soaring bird-like.

Steve and all,

Thanks for the kudos... this was a fun, worthwhile build. I'm always looking for something different in each of my planes, and this one certainly established its unique niche!

Originally Posted by Tom Frank

Thought I'd post some pics and video of my 56 in. eagle build since I made a few mods that might be of interest. I wanted to make the airframe a little more "bird-like"...

Just a note to mention I did some followup flight testing and tweaking of my eagle to get it flying to my liking. I edited my original build summary post with my findings to keep everything in one place.

I just stumbled across this site. It shows actual wings of hundreds of birds.

http://digitalcollections.ups.edu/cd...&CISOSTART=1,1

Excellent resource! Painting the thing has been what's putting me off so far.

Nick

Originally Posted by Skycruiser

Excellent resource! Painting the thing has been what's putting me off so far.

Nick

Here's a couple more:

Very nice pictures...well in a few weeks I will try to finish my bald eagle, the mould is almost ready ...hope I get it on the wing...[IMG][/IMG]

Well, I had my first major crash with my eagle.

It's kind of a funny story too. I was flying at the park and there was a young girl getting excited about seeing an eagle. I heard the Mom telling her "I don't think it's an eagle, it's an airplane". So I thought it would be cool to pull off a roll and see what they thought. Well I guess I had somehow gotten some slop in my aileron and when I cranked it to roll it actually came up far enough to get caught on the tail feather. This put it into a downward spiral that I had no way of getting out of.

But the funny part is the little girl burst into tears as soon as it started spiraling down. I could hear her crying as I walked out to retrieve my wounded bird. I think she finally calmed down when she saw me pick it up and realized it wasn't a real eagle that just fell to it's death...

Fortunately the eagle didn't take much damage and I'll be sure that the ailerons are fixed that it can't happen again!

Originally Posted by bluefalconhollan

Very nice pictures...well in a few weeks I will try to finish my bald eagle, the mould is almost ready ...hope I get it on the wing...[IMG][/IMG]

It's beautiful! Is that going on a wing like the FFF eagle? As a glider (slope?).

I'm visiting my daughter in Holland in late August... maybe you can show it to me then

Originally Posted by billwhit

Well, I had my first major crash with my eagle.

It's kind of a funny story too. I was flying at the park and there was a young girl getting excited about seeing an eagle. I heard the Mom telling her "I don't think it's an eagle, it's an airplane". So I thought it would be cool to pull off a roll and see what they thought. Well I guess I had somehow gotten some slop in my aileron and when I cranked it to roll it actually came up far enough to get caught on the tail feather. This put it into a downward spiral that I had no way of getting out of.

But the funny part is the little girl burst into tears as soon as it started spiraling down. I could hear her crying as I walked out to retrieve my wounded bird. I think she finally calmed down when she saw me pick it up and realized it wasn't a real eagle that just fell to it's death...

Fortunately the eagle didn't take much damage and I'll be sure that the ailerons are fixed that it can't happen again!

Sorry to hear that, Bill... too bad I wasn't there to capture the event on video for you Sometimes the human interest side of RC flying is the better part.

Originally Posted by Tom Frank

Here's a couple more:

Thanks. What I'm really after is the Australasian harrier hawk. There are quite a few down where I am, trouble is they're pretty shy and by the time I've stopped the car and got the camera out they've done a runner.

Nick

Help me out here. I built a 42" Eagle and kept the wing flat, except for the tips which are angled up. It does seem a little 'roll' touchy in flight sometimes. A fellow flier saw mine and wanted me to build him a 56" version. As I relook at what people have done it looks like most have some dihedral built into the wing plus the up-swept tips. Is this the best/more correct wing configuration? If so, what's the recommended dihedral at each tip before the up-swept break?

Originally Posted by Skycruiser

Thanks. What I'm really after is the Australasian harrier hawk. There are quite a few down where I am, trouble is they're pretty shy and by the time I've stopped the car and got the camera out they've done a runner.

Nick

Here's some of the Australian Swamp Harrier:
http://www.aviceda.org/abid/birdimag...fid=42&bid=572

Rick.

Originally Posted by Vantasstic

Help me out here. I built a 42" Eagle and kept the wing flat, except for the tips which are angled up. It does seem a little 'roll' touchy in flight sometimes. A fellow flier saw mine and wanted me to build him a 56" version. As I relook at what people have done it looks like most have some dihedral built into the wing plus the up-swept tips. Is this the best/more correct wing configuration? If so, what's the recommended dihedral at each tip before the up-swept break?

I believe 10% is allot of dihedral. I build it in on pretty much every thing. I like the stability it offers. I love a plane that is stable enough to maintain level flight at @ 1/3 throttle without any input. jp

Thanks. As I relook at the plans it does say 4 degrees dihedral. Silly me, when I saw that on my 42" I thought it meant 4 degrees at the tip, the rest of the wing flat. Duhhhhhhh. 4 degrees didn't seem like much for the tips so I went with a lot more. If I build the 56" version I'll be sure to do the wing right.