Cozy Mark IV Foam Pusher-Prop Plane Build

[edmond22]

am reading with so much interest. Hmm, learned quite a bit from the pictures man, thaanks Astro. You are really good at building, those rudders looks really like they can fly themselves. What power are you setting for this bird?

[AstroBoy]

Hi Edmond, i'm no aeronautical geek, but i like to observe in detail the real planes outlines and contours, on the real cozies the vertical wingtips have flat surface facing the outside and curved on the inside, i guess this shape helped to create vertical lifting forces inwards, aka, so both wingtips generated forces toward each other, the end result, little yawing moment = good forward stability, Mechplas' delta wingtips incorporated this mod and he reported the delta was much more stable (less or very little yaw moment), i think most flying wings has these yawing moment, maybe you want to incorporate this into your epp wingtips and see whether that little yawing moment disappears
Burt Rhutan knows what he's doing when he designed the canard called EZ, LongEZ, and then Cozy Mark III, Mark IV.
I'll be using the Himax 2812/0850 Outrunner BL motor from the F-15, it's the GWS stick mount type so it's easy to remove

[Mathieu]

Wing tips are now very common on airliners and such. On the Cozy Mark, it provides vertical stability, they serve another purpose though. They break up tip vortices caused by the wing. Just like in ground effect. Lowers drag.

[stuka]

AstroBoy, wat happen to cozy? more postings leh...

[justin]

astro
where u got the plans?
eps 400 enuff to fly this plane?

[Jcho]

AstroBoy, wat happen to cozy? more postings leh...

Alamak...he kena Edmond Virus lah....now seow flying wings project push back.

[AstroBoy]

Wa-Lau-Eh! i super poor after chinese new year, give out so much ang pow! my ATM very dry liao!
Yah-lah, kena Edmond22 "SCREAMO" flying wing virus
Will be continuing this cozy build again

Justin: I drew the plans on AutoCad, this plane still not finished building yet so i can't say for sure what is the final RTF(Ready To Fly) weight, which will also determine the suitable powerplant, please be patient for "to be continued"

[AstroBoy]

Ok, finished cutting up 30 pcs of foam for canopy, 3M77 spray glue used for this canopy build, tedious work man!
Well at least it's starting to look like a plane now
Will be shaping the canopy tomorrow night, tonight too tired liao! see too much foam at too close a distance!, i can still see whitish/opaque color when i close my eyes! Signs of getting to mid-life crisis
I glued 10 pcs each because my penknife is not long enough to continue cutting 30 at one go, so that's why there are 3 stacks of 10s, the 3 stacks are then glued together finally, PHEW!

[edmond22]

Ok, finished cutting up 30 pcs of foam for canopy, 3M77 spray glue used for this canopy build, tedious work man!
Well at least it's starting to look like a plane now
Will be shaping the canopy tomorrow night, tonight too tired liao! see too much foam at too close a distance!, i can still see whitish/opaque color when i close my eyes! Signs of getting to mid-life crisis
I glued 10 pcs each because my penknife is not long enough to continue cutting 30 at one go, so that's why there are 3 stacks of 10s, the 3 stacks are then glued together finally, PHEW!

Jesus mate! How you managed to cut those templates so accurately that they fit so nicely?!?! Hmmm, Artist hand you got there lol. Very nice! When do you reckon you will maiden this bird, doesn't look like much to go except for wing and power system.

[Jcho]

THIS WEEKEND?

[edmond22]

THIS WEEKEND?

(trying hard to add pressure):

hehehe, this weekend I forecast good fair day with light wind, perfect for maiden.

Seriously though, how much of throw and expo are you dialling in on that bird before you get comfortable enough to fly it?

[AstroBoy]

Edmond, Jcho, i would like to your heads, don't rush me ok! it's a !
I tend to get when pass mid-night, and i can't build every night

Aileron throw would be a conservative 10mm up and down, with maybe 5~10% aileron differential thrown in, will advise actual differential value once maiden, have to see for myself whether this bird will turn on it's axis or not, the CG has to be spot on

I usually give +30~40%(JR) exponential on all my maiden birds, total canard throw will be 60 degrees overall with about +40% exponential too, if CG is spot on, i may reduce canard throw, canard and main wing incidence will be 0 degrees, that means in line with fuselage, motor will have 2 degrees upthrust but no right or left thrust.

So far, the weight is in the 500 grammes region without electronics, still adding...

[Jcho]

:na but you are MASTER BUILDER...... lucky there is only one ASTROBOY, else no more hobby shop......we dying to see that plane fly....

[AstroBoy]

Honestly speaking, i don't even know whether can fly or not
And Jcho, why you point me 2 middle fingers har Don't use vulgar sign leh!

[edmond22]

hehehehehe :na

Anyway, Astro, the CG thing you are concern with, is really the right thing to do. I found out why my wing could not fly last week, apparently, I used a measuring ruler with inches and metric system and I think I got confused and took measurements wrongly. Jesus, that was a first but my supposed CG spot was off by almost 5 cm too aft! No wonder it was like a brick.