Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Need Prop for OS 35 AX and Pipe

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Old 10-31-2013, 08:29 AM
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mustangman177
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Default Need Prop for OS 35 AX and Pipe

Hi All !!!

New to the Extreme Speed forum here. Need help with a question.

I have a OS 35 AX with Mousse can muffler on a SPAD Sickle. Currently using a MAS 10 X 6. Speed is awesome, but was told I could get more with a different prop and higher pitch ? What would you use on this set up ?

Thanks in advance

Cary

Last edited by mustangman177; 11-01-2013 at 05:02 AM.
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Old 10-31-2013, 11:20 AM
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9 x 7 is the next guess
If the plane is small and light enough with good aerodynamic qualities then a 8 x 8 prop.
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Old 10-31-2013, 12:48 PM
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Here's a picture of one:

http://www.rcuniverse.com/forum/atta...8&d=1375344784
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Old 10-31-2013, 03:05 PM
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Pretty cool..!
I have a flying wing about this size on YouTube that is powered with a Fox .36 with open exhaust and a 8x6 prop. The wing is solid foam, it's thicker than this SPAD's and it's got a blunt leading edge [for good maneuvering].
110 MPH on a pair of 60 foot long .018" cables was really honkin'..somewheres around 2 seconds per lap. Each lap was about 380 feet.
This SPAD looks like it would be a lot faster, so the 9x7 and 8x8 might do pretty good.
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Old 10-31-2013, 05:55 PM
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I'd lean towards the 9x7 prop for the disc area. The OP already thinks a 10-6 on that engine is fast so I guess it might be good compromise of pull and airspeed. Peak hp appears to be at 16k from what I could find in a quick search, so those prop sizes seem about right.
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Old 10-31-2013, 07:14 PM
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9-6 or 8-7 might work better.
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Old 10-31-2013, 07:34 PM
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What size engine does that look like to you in that photo..?
It looks like a .15 to me....[?]
If so, then a .35 would seem pretty fast for sure.
Even though flying wings are limited in what they'll do they are still a lot of fun to horse around with.
Scale this idea down for that Profi .049, do whatever you can to keep the weight down, do you
r absolute best to keep weight off of it, but use generous wing area, a fast airfoil and use a 5x3 prop on it when you just want to get squirrely, or a 4x4 when you want to shift into high gear a little bit.
I've wanted to build something similar with one of my .32-.36 engines..keep it as light as a feather but go with 500 sq inches or more and just be as militant about weight control as possible. I came close to accomplishing something like this idea a few years ago and it was looking really good for about 20 seconds on the maiden before the wing exploded. It was a recycled combat plane, so no tears were shed.
About 25 years ago I tried this same idea with a Fox .36 Combat Special on a converted CL Combat wing but didn't know that the HS-81 servos I selected would only last about 5 minutes in such an application trying to control a 48 sq inch elevon flap at 110 mph. IIRC the plane crashed into a massive and fresh cow paddy to make a fitting end to my RC activities that day
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Old 11-01-2013, 05:00 AM
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Originally Posted by combatpigg View Post
9 x 7 is the next guess
If the plane is small and light enough with good aerodynamic qualities then a 8 x 8 prop.
Yes, plane is definitely small and light. Is a flying wing with elevons. Will try 9 X 7 or 8 X 8. Stick with MAS ? What other brands of props do the Speed guys use ?

Last edited by mustangman177; 11-01-2013 at 11:26 AM.
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Old 11-01-2013, 05:03 AM
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Originally Posted by combatpigg View Post
9 x 7 is the next guess
If the plane is small and light enough with good aerodynamic qualities then a 8 x 8 prop.
Yes, plane is definitely small and light. Is a flying wing with elevons. Will try 9 X 7 or 8 X 8. Stick with MAS ? What other brands of props do the Speed guys use ?


http://www.rcuniverse.com/gallery/galleryItem.cfm?itemID=233020&dummy=9835.00982629408&opener=/community/profile.cfm%3Fsection%3Dgallery%26memid%3D1690

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Old 11-01-2013, 05:59 AM
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APC has a 7-9" 8-8, 8-9. and a few more. The real high pitch ones will probably need someone else to launch for you with a pretty good shove for the first couple tries.
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Old 11-01-2013, 09:06 AM
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Originally Posted by aspeed View Post
APC has a 7-9" 8-8, 8-9. and a few more. The real high pitch ones will probably need someone else to launch for you with a pretty good shove for the first couple tries.

Will give those a try. Thanks !!!

Cary
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Old 11-01-2013, 07:53 PM
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That's not the cleanest airframe in the world. I have a strong feeling you will find out that 9" diameter works best. 9-6 as HP suggested is another I thought about, but the specs for the .35AX mention it being set up for peak power at lower rpm so figured that the 9-7 was a better candidate. Try them both! I am not convinced you will prefer the performance on 8" props. If this was a higher timed .35 a 9-6 would be my first guess. It might turn out well, but I imagine the engine will be over it's horsepower peak. Which somewhat defeats the purpose. It will be interesting to find out.
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Old 11-01-2013, 08:05 PM
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http://www.spadtothebone.net/freeplans.htm

40", 400 sq in.

Looks fun!
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Old 11-02-2013, 04:44 AM
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Originally Posted by MJD View Post

Good Cheap fun !!!!!

Easy to make-Addictive !!!
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Old 11-02-2013, 11:54 AM
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I'm assuming you will get this plane moving in the 120-130 mph range, so get some clockings........ then I would take clear packing tape and seal off all open cavities, like the wing tips to see how much difference that makes at this fairly high speed you will be flying at.. A simple "Coke bottle" plastic cowl can be made with a heat gun and even if it isn't museum quality give that a try and get some clockings with these aerodynamic improvements. It will show you first hand what is worth doing and what isn't in this speed / power range you are working with.
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Old 11-02-2013, 04:49 PM
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Originally Posted by combatpigg View Post
I'm assuming you will get this plane moving in the 120-130 mph range, so get some clockings........ then I would take clear packing tape and seal off all open cavities, like the wing tips to see how much difference that makes at this fairly high speed you will be flying at.. A simple "Coke bottle" plastic cowl can be made with a heat gun and even if it isn't museum quality give that a try and get some clockings with these aerodynamic improvements. It will show you first hand what is worth doing and what isn't in this speed / power range you are working with.
Thanks !!!
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