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Old May 03, 2010, 08:39 AM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Quote:
Originally Posted by rjmanzuk View Post
...3-bladed 11x8
Where can I find these? I can find 11x7s all day long, but have yet to locate an 11x8 pusher.
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Old May 03, 2010, 08:57 AM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Quote:
Originally Posted by Krylon View Post
If you're still having trouble gluing that plastic you could try NoNails, since all the non solvent adesives have been rigid glues, maybe it needs something with a tiny ammount of flex to stop the joint cracking.

http://www.diy.com/diy/jsp/bq/nav.js...&isSearch=true

This is the stuff, i expect you can get this or something similar where you are.
Excellent idea. I hadn't thought about those types of adhesives. I have a trip planned to the hardware store today to pick up stuff for my stabs, I'll grab something of this nature while I'm there.

Thanks again.
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Old May 03, 2010, 09:22 AM
aka MadMan
rjmanzuk's Avatar
San Diego, CA (USA)
Joined Aug 2006
633 Posts
pusher vs puller

Quote:
Originally Posted by NewEMan View Post
Where can I find these? I can find 11x7s all day long, but have yet to locate an 11x8 pusher.
Quite honestly, since this is my first pusher R/C model, I wasn't sensitive to the differences.
I would have reversed the prop on the motor shaft to get the flow going in the correct direction, but didn't realize that there were pusher props available until you pointed that out.

Will I have issues if I follow my original plan?

You're correct ... my sources have 11x7 pushers, but not 11x8s.
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Old May 03, 2010, 09:24 AM
aka MadMan
rjmanzuk's Avatar
San Diego, CA (USA)
Joined Aug 2006
633 Posts
Zap?

Quote:
Originally Posted by NewEMan View Post
Excellent idea. I hadn't thought about those types of adhesives. I have a trip planned to the hardware store today to pick up stuff for my stabs, I'll grab something of this nature while I'm there.

Thanks again.
And if that doesn't work, you might give ZAP GOO (PT-12) from your LHS a try. Keep us posted so we know what to expect as we begin our assembly.
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Old May 03, 2010, 09:29 AM
Gasbags & Gussets
jswain's Avatar
Riverside, Ca
Joined Feb 2009
1,213 Posts
11x7 pusher

Quote:
Originally Posted by NewEMan View Post
Where can I find these? I can find 11x7s all day long, but have yet to locate an 11x8 pusher.
The closest i have seen is a 11x7 pusher = http://masterairscrew.com/11x73-blad...er-pusher.aspx

js
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Old May 03, 2010, 09:44 AM
Traded in the F15 for MQ9
F15Ejetmac's Avatar
Alamogordo, NM
Joined Jul 2008
51 Posts
propeller info, Tail mod

I found an adjustable three blade prop here --> http://www.hobby-lobby.com/scale_3_b...18579_prd1.htm
Three blade pusher props here --> http://www.hobbypeople.net/prdcls/propst01.asp

Im not sure which way to go.......


NewEMan; your tail mod is spot on, I will have to see if I can undo mine.... Im not sure why you would think there would be any drag from this since it's inside the fuse......as long as you make sure there is no slop everything should be fine.
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Old May 03, 2010, 09:45 AM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Quote:
Originally Posted by rjmanzuk View Post
Will I have issues if I follow my original plan?
Well I'm not a fluid dynamics engineer, but I do know that even the small props we use actually have a defined airfoil shape.

I think that most people that have used std props as pushers have done so with nitro engines, which when the engine is turned around and the prop is turned around; the prop is then actually spinning backwards...

imagine flying your airplane in reverse and the wind in kind flowing over your wing from aft to front. You still have the airfoil affect for lift, but it wasn't designed to operate like that and so you lose some efficiency of the wing/prop.

However, with motors...they can run backwards by switching the poles, correct? (I'm fairly new to the whole electric scene and am not sure/aware of all caveats) So in this case the motor runs backwards and the prop runs in its std fashion.

Are these new electric airplane motors designed to only run efficiently in one direction? Obviously, most people run them in a std manner because most planes are tractor in nature...and as such they are wired/marked positive/negative.

but if there is no problem with running a motor backwards, the your prop will be swinging forwards and all is good.

Any thoughts on running a high efficiency motor backwards?
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Old May 03, 2010, 09:53 AM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Quote:
Originally Posted by F15Ejetmac View Post
...Im not sure why you would think there would be any drag from this since it's inside the fuse......as long as you make sure there is no slop everything should be fine.
Thanks for the kind words.

Since in effect the only thing holding the stabs "on" would be the pin (and I guess the friction of the spar, alignment pin and elevator linkage), I was concerned about the inherent drag that all fly surfaces create/encouter and whether or not that drag would be too much for the countering forces.

I think the epoxy used to glue the stabs on would have greater staying power than those keeping/fricition devices I listed, but then I'm not going to to be hanging the airplane by them.

Guess I'm just playing the devils advocate.

If you already installed your spar in the stab, but not glued the stab in place...

Then you could probably tap the hollow spar and use a similar setup.

1) Put the elevator in
2) Use a snugly washered hex bolt that can screw into the spar there by pulling it in.

(Just be careful not to crush the fiberglass tube)

As a matter of fact this actually sounds better to me than my first solution. Just be careful with the spar, that is some soft metal.
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Last edited by NewEMan; May 03, 2010 at 10:12 AM.
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Old May 03, 2010, 10:00 AM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Prop Options

Quote:
Originally Posted by F15Ejetmac View Post
I found an adjustable three blade prop here --> http://www.hobby-lobby.com/scale_3_b...18579_prd1.htm
Three blade pusher props here --> http://www.hobbypeople.net/prdcls/propst01.asp

Im not sure which way to go.......
Thanks for the prop info. Although the adjustables are nice I think they may look a little funny on this bird when it is sitting at rest.

Since there is obviously a lack of variety in the pusher prop market, our best option may be to hold out hope for running motors backwards and using std props, or just settling for what is available...buts that's no fun.

To be continued....
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Old May 03, 2010, 10:29 AM
What goes up...
Krylon's Avatar
England
Joined Apr 2010
198 Posts
I dont know of any reason you can't run one of these new motors backwards.
Haven't got one atm to test that unfortunatly.
I would be very hesitant to use that adjustable prop though

"* NOTE - These props are for Electric Parkflyer Aircraft ONLY! They are NOT for use with glow engines or extremely powerful electric motors!"

The size motor we're talking about for the MQ-9 Could easily lift a 40 trainer of the ground so it might be a little to powerfull for one of those props.

Personally im planning to just run the moror backwards with a standard prop on it. Unless of course someone steps in to tell me it can't be done
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Old May 03, 2010, 10:41 AM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Quote:
Originally Posted by Krylon View Post
I dont know of any reason you can't run one of these new motors backwards... Unless of course someone steps in to tell me it can't be done
I posted the question on the motor board to see what has to be said about it. Seems like it should be cut and dry okay to do it, but you never know...

Don't want to burn up a new motor...

http://www.rcgroups.com/forums/showthread.php?t=1238380

No answers as of 11:41am EST today.
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Old May 03, 2010, 11:55 AM
Traded in the F15 for MQ9
F15Ejetmac's Avatar
Alamogordo, NM
Joined Jul 2008
51 Posts
GUYS
Three blade pusher props here --> http://www.hobbypeople.net/prdcls/propst01.asp
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Old May 03, 2010, 12:21 PM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Quote:
Originally Posted by F15Ejetmac View Post
GUYS
Three blade pusher props here --> http://www.hobbypeople.net/prdcls/propst01.asp
Thanks. I took a look at that one earlier, but they too do not have an 11x8, got a 12x8, close, but sadly it is on backorder....oh the humanity of it all.
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Last edited by NewEMan; May 03, 2010 at 12:32 PM.
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Old May 03, 2010, 12:59 PM
Sir Crash Alot
Tallahassee, FL
Joined Feb 2010
73 Posts
Go Run That Baby Backwards!!

I found the proof:

http://www.rcgroups.com/forums/showt...motor+backward

Apparently with these new motors/escs it doesn't matter; their as flexible as Gumby. Had we been dealing with older motors then we might have had a problem, but it looks like the flight path is clear.

What were we talked about, something called a "pusher prop", oh well doesn't matter, on the std props hoooooo!!!
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Old May 03, 2010, 01:23 PM
Traded in the F15 for MQ9
F15Ejetmac's Avatar
Alamogordo, NM
Joined Jul 2008
51 Posts
MQ-9 Photos

I thought I would post a link or two for reference photos.

http://www.af.mil/photos/mediagaller...galleryID=5368

http://www.ga-asi.com/resources/imag...predator_b.php

more info than photo's here --> http://en.wikipedia.org/wiki/MQ-9_Reaper
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