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Old May 23, 2012, 01:46 PM
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Raleigh, NC
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Quote:
Originally Posted by MRGTX View Post
I have one of these 5x5 scimitar style props around...would this hold up to ~1000W?
http://www.valuehobby.com/accessorie...itar-prop.html

Thanks
Both EMP and TRG (hobby city) make better 5x5 props. (the one in your link is an EMP prop)

Usually the rating is by RPM. You probably want to find the manufacturers rating on that prop and make sure it's within the limit of the RPM your setup generating.
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Old May 23, 2012, 02:08 PM
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Staffs, UK
Joined Apr 2009
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Quote:
Originally Posted by cjbucher View Post
Part of the problem is that 5x5 prop (especially if it's an APC prop). APC makes great props but the 5x5 is one of their worst. It really was only made for fast pylon planes that have very low drag.
I'm not convinced it's that good on pylon planes either TBH. I've got a Simprop Turn Left (ok, only an F5D trainer) and the worst seemed to be the 5x5 when I used to run a Het 3W. I agree it takes a little to get going, but I'm not convinced it was any quicker than a 4.75x4.75. Launching was never a problem so I didn't try a 5.25x4.75, I figured it'd spin slightly slower so kept the square 4.75 on.

I'm not a fan of those EMP props either.
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Old May 23, 2012, 02:49 PM
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Quote:
Originally Posted by feefo View Post
I'm not convinced it's that good on pylon planes either TBH. I've got a Simprop Turn Left (ok, only an F5D trainer) and the worst seemed to be the 5x5 when I used to run a Het 3W. I agree it takes a little to get going, but I'm not convinced it was any quicker than a 4.75x4.75. Launching was never a problem so I didn't try a 5.25x4.75, I figured it'd spin slightly slower so kept the square 4.75 on.

I'm not a fan of those EMP props either.
A few years ago I posted a thread in the Power Systems section about how terrible I thought this prop was. Many people agreed but a few of the high performance plane guys defended the prop saying it worked well in their application.

Also Dr Kiwi who does a lot of power system evaluations agreed that it was indeed a terrible prop.
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Old May 23, 2012, 03:34 PM
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I used to run the 5x5 on a TT Velocity (Projeti clone) with a 2700kv outrunner. At the time it seemed ok, and was visually faster than a 5.5x4.5. Maybe it does 'work' on certain motors and airframes, maybe a much higher RPM is needed to get the best from it?

I've also got the 4.75 (dia) x5.5 (pitch) pylon prop. Again it doesn't seem to work as well as some motor calc programs suggest it should. I think it might need the pilot to be more presise in turns to get the best from it, basically to keep the plane 'on song' the whole time or you lose the benefit of it?
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Old May 23, 2012, 04:17 PM
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Quote:
Originally Posted by feefo View Post
I used to run the 5x5 on a TT Velocity (Projeti clone) with a 2700kv outrunner. At the time it seemed ok, and was visually faster than a 5.5x4.5. Maybe it does 'work' on certain motors and airframes, maybe a much higher RPM is needed to get the best from it?

I've also got the 4.75 (dia) x5.5 (pitch) pylon prop. Again it doesn't seem to work as well as some motor calc programs suggest it should. I think it might need the pilot to be more presise in turns to get the best from it, basically to keep the plane 'on song' the whole time or you lose the benefit of it?
I did several tests with the 5x5 and the 5.5x4.5 and used doppler to compare. The 5.5x4.5 was consistently faster and had better acceleration. This was on a 2700 kv turnigy and a 40" flying wing.
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Old May 23, 2012, 05:50 PM
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Which prop is faster depends a lot on the airframe.

The higher the drag: advantage 5.5X4.5

The lower the drag: advantage 5X5

--------

A certain tester used to test up to 30-35A on 3S-4S and "within" manufacturer "limits", I hope he has upped his game in last few years.
I think I saw some 50-60A tests while back.

Gryphon
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Old May 23, 2012, 06:54 PM
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Rogersville, Mo
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Quote:
Originally Posted by GryphonRCU View Post
Which prop is faster depends a lot on the airframe.

The higher the drag: advantage 5.5X4.5

The lower the drag: advantage 5X5

--------

A certain tester used to test up to 30-35A on 3S-4S and "within" manufacturer "limits", I hope he has upped his game in last few years.
I think I saw some 50-60A tests while back.

Gryphon
+1...On my Projeti it applies...its faster on 5x5........Billy
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Old May 23, 2012, 07:05 PM
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There is also graupner 5.2x5.2
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Old May 23, 2012, 09:52 PM
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Rogersville, Mo
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I'll look and see if i got one of those.....BTW....Benn workin on the Ultra....I went with Black on the ailerons as well as the fins....waiting on my Green Zagi tape to be shipped...I think you'll like the look Rim!!!!....Billy..
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Last edited by FlyBillyFly; May 24, 2012 at 02:24 PM. Reason: Tape arrived today....
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Old May 25, 2012, 11:37 AM
No such thing as overpowered
Wilit run? 353's Avatar
Suffolk, England
Joined Sep 2008
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I think my FunJet Ultra is too heavy, my motor weighs 369g!

Is there a point where the FJU is too heavy to launch, I hope to run 6s so how has every one coped so far?
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Old May 25, 2012, 11:40 AM
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USA, IN, Fort Wayne
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Quote:
Originally Posted by FlyBillyFly View Post
I'll look and see if i got one of those.....BTW....Benn workin on the Ultra....I went with Black on the ailerons as well as the fins....waiting on my Green Zagi tape to be shipped...I think you'll like the look Rim!!!!....Billy..
So did you just basically make a skin of tape over the airframe?
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Old May 25, 2012, 12:22 PM
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Quote:
Originally Posted by Wilit run? 353 View Post
I think my FunJet Ultra is too heavy, my motor weighs 369g!

Is there a point where the FJU is too heavy to launch, I hope to run 6s so how has every one coped so far?
'
well it depens on how strong you are and how hard you can throw, maybee you need a bit of luck also... Mine did torque to death on a 155gram motor and 5s lipo, and I can throw hard and stright, didnt help..

Its like playing roulette ,, I wouldnt want a Ultra with a 369 gram motor on 6s and hand trow it.. but heck, try it, maybee you are lucky... I was lucky the first 3 times, then I couldnt throw it ,,, I tried 10 times before the airframe gave up..

My 4s funjet with a 120 gram motor is soooooo easy to throw..
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Old May 25, 2012, 01:08 PM
Static Model Collector LOL
Katy, TX
Joined Dec 2009
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If itís too heavy, and you are not comfortable hand launching, build a PVC launcher.

FCA
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Old May 25, 2012, 01:45 PM
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Alberta,Canada
Joined Nov 2009
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Quote:
Originally Posted by Wilit run? 353 View Post
I think my FunJet Ultra is too heavy, my motor weighs 369g!

Is there a point where the FJU is too heavy to launch, I hope to run 6s so how has every one coped so far?
What's your AUW?
369g inrunner is going to make you good power,I would just vertical launch it.
What size 6s are you packin?
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Old May 25, 2012, 01:59 PM
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United States, MI, Port Huron
Joined Jun 2006
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Quote:
Originally Posted by Wilit run? 353 View Post
I think my FunJet Ultra is too heavy, my motor weighs 369g!

Is there a point where the FJU is too heavy to launch, I hope to run 6s so how has every one coped so far?
Mine is 3 lb 3 oz , thinking 1400-1500 grams, its a load but other then a little torque roll and hot landings its fine, never a bad launch.
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