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Apr 01, 2008, 09:51 PM
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Experts weigh in...profile Bird of Prey


Don't think this one has been done yet.

Take a look and offer some sugestions. In 'flight mode' the Bird of Prey has some dihedral, so that's what I'll model. I'm convinced the box structure helps stabilize the model (base on eliworm's F-15, my Gripen, and my unpublished profile Berkut), so that's how I'll model this one. Power will be the tried-n-true Suppo 2212 APCe 6x4 combo. 30 inch span.

My questions to the quorum are:

1. What's a good angle to set the wings?
2. Will I need some vertical stab behind the prop?

Just starting to model this PM, so post up your thoughts.

Kevin
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Apr 01, 2008, 09:59 PM
My plans are in my blog
Rusty-Gunn's Avatar
I 'd guess the plane may want to topple over with the severe anhedral and most weight high above. Might give you some moments of sudden suprise maybe?
Looks to be a nice idea though. Give it a try and have at it. Its the best way to discover how it will work.
Apr 01, 2008, 10:02 PM
Foam Wannabe
Edgerc has their Bird of Prey kit. It is sort of along the same lines:

http://www.edgerc.com/bop.htm

Ron
Apr 01, 2008, 10:58 PM
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Quote:
Originally Posted by Rusty-Gunn
I 'd guess the plane may want to topple over with the severe anhedral and most weight high above. Might give you some moments of sudden suprise maybe?
Looks to be a nice idea though. Give it a try and have at it. Its the best way to discover how it will work.

No anhedral. The first picture has the BOP in flight mode - that's what I'm modeling.

KW
Last edited by kwinters; Apr 01, 2008 at 11:36 PM.
Apr 02, 2008, 12:03 AM
"It's a Quad" :O
thewz's Avatar
Looks good but be careful with too much vertical surface area forward of the CG.
Apr 02, 2008, 12:07 AM
Retired CAD guy
birdofplay's Avatar
Go take a look at the Harpy thread by Chara
Apr 02, 2008, 12:17 AM
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Quote:
Originally Posted by thewz
Looks good but be careful with too much vertical surface area forward of the CG.
What adverse effect will this have to flight characteristics?

Will check out harpy thread.

KW

Preliminary layout video here.
Apr 02, 2008, 05:27 AM
Or am I...
Look for my F-28 parkjet vids somewhere here in the vid forums or parkjets.com . I had too much in front initially and the vid shows what happens.
in a nutshell, the plane wants to weathervane backwards and becomes unstable in yaw.
Apr 02, 2008, 07:00 AM
Crash Master
Gene Bond's Avatar
Check out the annehdral/dihedral on the BluBat: https://www.rcgroups.com/forums/showthread.php?t=401764

The optical illusion works well, and flight personality is tame.
Apr 02, 2008, 03:39 PM
SG Talon... Super Genius.
I think that looks awesome Winter!

I was actually looking at my Star Trek Models the other day and thought it would make an awesome plane. Put a rudder on the thing to counter any extra yaw problems and i bet it will be great.

I think that perhaps this will be the summer of Space Vehicles for my Prototype shop. I feel a rash of Star Trek and Star Wars models in my blood.

Course it could be the Pon Farr.
Apr 02, 2008, 10:20 PM
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Quote:
Originally Posted by SGTalon
I think that looks awesome Winter!

I was actually looking at my Star Trek Models the other day and thought it would make an awesome plane. Put a rudder on the thing to counter any extra yaw problems and i bet it will be great.

I think that perhaps this will be the summer of Space Vehicles for my Prototype shop. I feel a rash of Star Trek and Star Wars models in my blood.

Course it could be the Pon Farr.

Thanks. Keep checking back. I'll start cutting foam this weekend.

KW
Apr 03, 2008, 01:31 AM
You sabotaged my plane.
eliworm's Avatar
KW, very cool. Can't wait to see this one.

Jim
Apr 03, 2008, 02:58 AM
Sopwith Camel's Cousin
If it turns out that you need more vertical stabilizer later on,
you could try to make the added stabilizer out of clear plastic
(with perhaps some thin CF rod as a stiffener if needed)
to minimize its visibility (cloaked ).
Apr 03, 2008, 07:55 AM
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Design work is 90% done. 15 degress of dihedral. Everything is slotted/tabbed to fit together except wing-to-nacelle. Should finish up tonight. I'll withhold posting plans unless someone is going to build alongside me.

Was thinking about pitching moments this AM. On my other flat foamies I placed the centerline of the motor ALONG the trailing edge of the wing. For this design, I placed the motor ABOVE the wing.

Q: Will this cause excessive pitching as throttle position is changed? Is vertical positioning of the motor significant or trivial for flat foamies? See attached picture and offer your thoughts.

KW
Apr 03, 2008, 07:58 AM
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Jim -- thanks. I still fly your F-15 every day. I have a buddy who is modeling panel lines of the F-15. I'll print them onto vinyl graphics and attach them to my second plane (remember, I bought two from you). Also, I started playing with video, so I'll post some video on your thread when I can...

Llama -- good call. Hoping I won't need additional vertical stab, but I like the method you proposed. Flight testing will tell...

KW


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