Jon if i may.. Why a flat airfoil and not undercambered ??

Originally Posted by Vyceroy

Jon if i may.. Why a flat airfoil and not undercambered ??

A very good question and the reason is that because of the method of construction and materials used, mainly the sticker material that carries the detailed illustrations, the wing is best off flat. The material the stickers are made from is very directionally stable - ie doesn't stretch. This makes it extremely strong and resistant to impact and damage but this also means it likes to lie very flat.

It can be applied to simple curves but does not conform to complex curves. But also it will not stay on an under cambered surface effectively. It eventually peels itself off.

It also makes for a simple process for assembly from kit form. We'll see how it works in flight tomorrow with any luck.

Jon

Conditions were light with a swirling 2-3mph dying down to almost nothing towards the end of the test.

First flight was very tail heavy - so much so Simon on 'camera 1' (the only camera) couldn't follow it. Managed to set it down gently and added about 6g to the nose. There is room to shift the ESC, Rx and battery forward by up to 8mm so this should reduce the dead weight required in the production model. Some thrust angle adjustment too, down.

With the nose now weighted the Hawk took off fairly gently with a spot of rudder input and up elevator as I'd applied too much thrust angle adjustment

It was responsive to all inputs and needed a few clicks down on elevator (nose still a bit light) in trim. Very tame stall characteristics and floats around nicely.

There are several design changes required though.

The fixed undercarriage needs to be beefed up. The Depron leg fairing that sits over the leg wire, creased where it joined the fuselage and eventually collapsed after several nose over landings so the undercarriage was no longer stiff. A combination of lightened ply with the existing wire should do the trick. The ply will then be covered in the sticker material.

The ailerons need to have a larger throw. They are a little lack-luster in performance and the only time I could roll the aircraft was when I'd taken the failed undercarriage off. However I had my suspicions that this would be the case and it's just a matter of increasing the length of the control arm in the lower wing and maybe a small adjustment in the attachment point of the control strut on the aileron itself towards the hinge.

The wing incidence relative to each other also need to be slightly closer, within 1-2 degrees. I was able to adjust it in the field and the closer to equal they got the better the aircraft behaved.

I'm also thinking of dropping the scale to 1/22nd to increase power to weight which should make it more aerobatic. It loops reasonably but it's not big. And the COG should be easier to achieve without ballast at that scale.

Video rendering at the moment. Will pop it up to Youtube shortly and post.

Jon

Two thoughts:
1. Given the CF rod through the fuse, can you increase the size of the holes at the rear of the aircraft to lighten the tail?
2. Does the foam LG strut need to be functional? I recently built the Stevens Aero Heath LNB-4 (http://www.stevensaero.com/StevensAe...t-p-20619.html) and their design choice was to run the LG wire over the strut, so it is not functional at all. The struts free- float. That way the wire can flex without breaking it. It's not really visible in the pictures on the SA site, but I'll try to post one to show you what I mean.

Hi djhurlbut,

Some interesting points and ideas. I would prefer the LG leg shrouds to be fixed like they are on the full sized aircraft. I have some ideas on this - using the thin plywood that is also used in the struts. This is also then covered in the sticker material. It may be that I can eliminate some of the the LG wire also if I do this.

I dont think I can remove much more depron in the rear. I cleared as much as I dare knowing that this aircraft would be tail heavy anyway.

I'll just have to move everything I can forward and see how that effects things. The other option is to install a bigger battery!

Jon,
Glad to see this one is coming along so nicely but don't forget that they weren't really THAT aerobatic. Certainly nothing like the performance of your other models. Loops, stall turns and a lazy roll would be about it so perhaps you aren't too far off the mark for scale performance.
Whatever, it's starting to look the business and should be stunning with graphics applied.

Pete

Microaces Curtiss P-6E Hawk - First Stage Prototype (4 min 53 sec)

Very striking in the air Jon .. looks to be a winner .. congrats on the maiden .. cant wait to see the graphics..

This is the area on the tail I was referring to. I know you might want to be cautious on the vertical stabilizer, but you have CF running right underneath the horizontal stabilizer. It looks as though you could cut a hole in the fuse equivalent in proportions to the one just forward of this area. You might be able to lighten the vertical stab also, perhaps using a couple of smaller holes, but that would need some testing.

Love the video, it looks great!

Dennis

Well done Jon !

What a beautiful aeroplane.

RF

Looks like your definitely on the right track. Looks great in the air!!!

Mike

This looks awesome, it's the kit I'm gonna get!
I was going for the Stuka, but now I see this flying I'm glad it won!
Regards Nath

Wow - can a fleet of WWI biplanes be far behind?

Gene K

Originally Posted by djhurlbut

This is the area on the tail I was referring to. I know you might want to be cautious on the vertical stabilizer, but you have CF running right underneath the horizontal stabilizer. It looks as though you could cut a hole in the fuse equivalent in proportions to the one just forward of this area. You might be able to lighten the vertical stab also, perhaps using a couple of smaller holes, but that would need some testing.

Love the video, it looks great!

Dennis

Your right - there should be some scope for increasing the air in that area. I have to ensure there is something to grip onto the tail wheel 'retaining loop' that gets sandwiched between the two fuse halves but I think 2 holes in that area could be managed.

Jon

Jon.

Any chance you'll be offering an airframe only kit for those of us who have the innards stockpiled?

Gene K