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Old Sep 10, 2007, 06:41 PM
Foam Wannabe
Joined Nov 2005
578 Posts
Dek,

Thanks. Your pictures and those in the other thread explained the engine mounting to me.

I do have another question though. I'm confused now by thrust angle (I'm easily confused though, so no problem). Looking at the plane from the back, right side up, it looks to me like the motor is angled to the left. The way I understood side thrust was that on a pusher if the motor was behind the CG angling the motor to the left like yours is would cause the plane to rotate around the CG, causing the nose of the plane to go left. I know we want right thrust to counteract the motor/prop rotation, but it looks backwards to me in your setup.

Again, I'm easily confused especially on this issue. Thanks for the assistance.

Ron
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Old Sep 10, 2007, 08:06 PM
Crash & Burn
rmgmag's Avatar
Glastonbury, CT
Joined Nov 2004
2,502 Posts
Quote:
Originally Posted by firetrappe
Dek, Very nice build . I'm glad it worked out like you hoped it would. I might even have to build one myself now you've tested it

Si.
FT, how about another build thread!!

Bob
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Old Sep 10, 2007, 09:08 PM
VBARRRR
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USA, CA, San Bruno
Joined Jul 2007
2,502 Posts
wow dekan, i've been looking for something simple to build out of 1 inch styrofoam i found at Pier 45 in San Francisco

and i think this really fits the wallet ^_^

oh and the styrofoam is what used to make boxes and coolers and stuff

i found about 70 6'x1' sheets out there, they're a little dirty, but i could clean it up ^_^
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Old Sep 10, 2007, 09:51 PM
teched88
SW PA
Joined Feb 2007
347 Posts
NICE!


................. Subscribed
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Old Sep 10, 2007, 10:28 PM
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LLoo's Avatar
Guelph, Ontario Canada
Joined Sep 2004
666 Posts
Hey Dekan, Looks sharp!

Ever thought about implementing vectored thrust? I built an EPP F22 this past summer and it did this crazy flip. It's a whole lot of fun.

Two weeks ago I got to see a real F22 at the CNE Airshow and to my surprise it did the exact same flip! That was such a thrill. Anyway, here are my specs to the one I built.

WS - 16"
Length - 23"
Motor - UH 10g 2000kv motor
Battery - 460mah 3S
AUW - 4.4oz
Mini-Raptor (2 min 40 sec)


Leon.
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Old Sep 10, 2007, 11:05 PM
You deserve my opinion
FirstShirt's Avatar
Collierville, TN
Joined Apr 2005
1,497 Posts
Nice, Dekan! I can't think of a better place to put EPP than on the nose of a jet!
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Old Sep 11, 2007, 01:48 AM
D'oh.. Dumb Left Thumb
dekan's Avatar
London, UK
Joined Nov 2006
5,398 Posts
Ron,You have got me worried... you may be right. I have taken the side thrust out and will try flying without it.
I only added on some advice from a FB.....
Let me know if you need info on CF sizes and placement.
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Old Sep 11, 2007, 10:08 AM
Foam Wannabe
Joined Nov 2005
578 Posts
Dekan,

I'm definitely not an expert here, my "understanding" is definitely open to change. I was asking because I was hoping somebody that knew better would chime in, or you'd set me straight. Maybe one of the experts will chime in about right and down thrust on a pusher.

Si, any thoughts?

Ron
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Old Sep 11, 2007, 10:14 AM
Build 2 Bounce!
Birmingham, UK
Joined Jul 2006
1,660 Posts
Quote:
Originally Posted by rmgmag
FT, how about another build thread!!

Bob
Hi Bob, If I build one i'll be sure to take some photos as I go along. It looks like a lot of the Infi guys are building Jets at the moment....Bill's just built a really nice F22, Trug's building a Flanker and Flash is building an SU-27. I'm starting to feel like the odd one out .
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Old Sep 11, 2007, 10:17 AM
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DRITCH's Avatar
ST.LOUIS
Joined Aug 2006
1,999 Posts
Not an expert. Mine had 0_0. Flew fine. No pitch up/down with power. Level flight at full power ok. No pull to left or right with power. Flew hands off straight as an arrow.

http://www.rcgroups.com/forums/showthread.php?t=711684
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Old Sep 11, 2007, 12:32 PM
D'oh.. Dumb Left Thumb
dekan's Avatar
London, UK
Joined Nov 2006
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Rob. my understanding of thrust lines is based on info imparted to me by an old time modeller long long ago in a Galaxy far from here.LOL

Its basical this.... In front of the Cg aim the motor in the direction that you want the plane to go. Behind the Cg aim the motor the way you want the tail to turn, Ie like rudder on a boat.
I thought,originally, that the Cg on the F22 would be on the prop slot so I aimed the motor right, looking down from the top...but the Cg turned out to be about 3" in front of that. so as you say the motor was now pointing in the wrong direction.
Dritch it was your thread that started me of looking for an F22 design that would work in EPP, so thanks to you and all the other peoples work I have absorbed in the process.
Ft. Where can I find Bill's ideas on F22's ?
Good video a hot ship! Leon. Mine looks a lot easier to fly
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Old Sep 11, 2007, 12:45 PM
Build 2 Bounce!
Birmingham, UK
Joined Jul 2006
1,660 Posts
Ron, I think you must have me confused with someone else, i'm certainly no expert. I think you're initial thoughts are correct, the thrust angle is related to the cog (and whether you're using a pusher or tractor prop). When dek and myself were talking about this model a few weeks ago neither of us were exactly sure where the cog should be. As a result, the cog was too far back when it was maidened and it was horrible to fly.

As Ritch says, I'd personally go with zero/zero thrust to test it and then shim the motor later if you really think it needs it. If you look at plans for other similar pusher models you'll see there are very few that specify more than a degree in either direction.

HTH
Si.
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Old Sep 11, 2007, 12:49 PM
Build 2 Bounce!
Birmingham, UK
Joined Jul 2006
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Dek, Bill's F22 is in this thread : http://www.rcgroups.com/forums/showthread.php?t=723890

Si.
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Old Sep 11, 2007, 12:54 PM
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ST.LOUIS
Joined Aug 2006
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Funny how I've seen several posts about how the 22 would never make a good rc model because it had too many bad habits. Now there's plans for about every size and every foam, from full fuse contoured to simple profiles.
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Old Sep 11, 2007, 09:14 PM
Foam Wannabe
Joined Nov 2005
578 Posts
Well Si, it just shows that your are humble. I guess expert is a relative term to your own knowledge, mine in this case. I have followed quite a few of your build threads which are truly amazing to me. Thanks for all the assistance you provide in this forum.

Dekan, great explanation, thanks for explaining so well and putting another model on my list to get to, lol.

Ron
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