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

DC F-20 RIGHT PROP ?

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Old 10-12-2005, 08:36 PM
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BILLIUM
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Default DC F-20 RIGHT PROP ?

HELLO, I JUST GOT A DC F-20 TIGERSHARK W/ OS 46 SF ON TUNED PIPE IT HAS A APC 10*6 ON IT NOW . IT'S FAST BUT I THINK IT COULD DO BETTER . WHAT ARE YOU GUY'S THOUGHT'S THE PLANE IS 6.5 LBS W/ RETRACK'S. ANY INFO WOULD BE A GREAT HELP!! THANX BILLIOM
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Old 10-12-2005, 09:02 PM
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Cyclic Hardover
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Default RE: DC F-20 RIGHT PROP ?

I use 9/7apc.
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Old 10-13-2005, 09:10 AM
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Default RE: DC F-20 RIGHT PROP ?

The 9x7 cyclic noted is a good place to start. Should put you right in the best RPM range.

What really will determine what prop and speed you will get is your pipe length and what rpm you are getting now with the 10x6.

The pipe works to boost rpm, but set to long, and actually work as a governor and limit rpm. If the pipe was properly tuned for the 10x6, go down to a 9" dia prop, and select a pitch that turn about the same rpm on the ground.

On the OS46SF, you want to set up the prop and pipe combination so the engine is turning around 15,500 on the ground.
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Old 10-13-2005, 09:31 AM
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Default RE: DC F-20 RIGHT PROP ?

THANK YOU, IT'S RAINING BIG TIME I'LL HAVE TO WAIT TILL THE WEEKEND TO TRY IT. ANY IDEA OF THE SPEED ?A BUDDY AT THE FIELD HAS A .50 DUB JETT WE MIGHT PUT IN . WHAT IS A GO PROP TO START WITH ? THANX BILL
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Old 10-13-2005, 10:11 AM
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Default RE: DC F-20 RIGHT PROP ?

I have the same combo DC F-20 & 46 FX but with a Macs magic pipe . On 10% Omega it runs an apc 10x7 at 14,400 rpm.
I have a new 50 SX waiting for run in but I doubt it will give a significant improvement.
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Old 10-13-2005, 11:14 AM
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Default RE: DC F-20 RIGHT PROP ?

ORIGINAL: BILLIUM

THANK YOU, IT'S RAINING BIG TIME I'LL HAVE TO WAIT TILL THE WEEKEND TO TRY IT. ANY IDEA OF THE SPEED ?A BUDDY AT THE FIELD HAS A .50 DUB JETT WE MIGHT PUT IN . WHAT IS A GO PROP TO START WITH ? THANX BILL
Yeah, lots of rain in some places recently! I was watching on the news about the folks up in New Hampshire..... wow...

Speed on the F-20 depends on a lot of things. A good one, with the gear up, and with any decent 46/50 engine in the front, should exceed 100 mph.

Several I know of were confirmed to fly over 120 mph.

If you used the Jett SJ-50 engine, use a 9x8 or a 10x6. Let the engine turn up. Find peak rpm, back the needle off 500-600 rpm. Either prop will keep you happy
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Old 10-13-2005, 12:09 PM
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Default RE: DC F-20 RIGHT PROP ?

THANX BOB, DOES JETT HAVE A WEB SITE ? PLEASE ADVISE ! BILL
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Old 10-13-2005, 12:36 PM
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Default RE: DC F-20 RIGHT PROP ?

yes indeed

www.jettengineering.com

(and actually if you click on one of the keyword links - an underlined JETT -- it will take you there too... just costs me 5 cents )
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Old 10-13-2005, 10:24 PM
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Default RE: DC F-20 RIGHT PROP ?

Like i said I run a 9/7apc but I also have a 9/9apc to try out.
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Old 10-13-2005, 10:43 PM
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Default RE: DC F-20 RIGHT PROP ?

will do!! thank you, Bill
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Old 10-13-2005, 11:04 PM
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Default RE: DC F-20 RIGHT PROP ?

how are you guy's finding out your speed's ? with a gun or a small gps like a etrax inside the plane? i know it would add a little to the wt/ would it make a big difference. bill
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Old 10-14-2005, 07:56 AM
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Default RE: DC F-20 RIGHT PROP ?

Some folks use radar gun setups... a few have eagle tree air data systems. I kinda like the eagletree system myself.
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Old 10-14-2005, 10:52 PM
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Default RE: DC F-20 RIGHT PROP ?

hi guy's , got a chance to fly today between rain shower's, put a tach on my f-20 w/ 10*6 prop got 13200 rpm tried a 9*6 got 15800 rpm and tried a flight prop screamed like hell but the speed was not there !! try again saterday a buddy has a 9*7 mayby have better luck let you guy'S KNOW HOW IT TURN'S OUT .LATER BILL
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Old 10-14-2005, 11:11 PM
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Default RE: DC F-20 RIGHT PROP ?

I use a simple time/distance method
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Old 10-14-2005, 11:13 PM
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Default RE: DC F-20 RIGHT PROP ?

DON'T UNDERSTAND ?
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Old 10-15-2005, 07:18 AM
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Default RE: DC F-20 RIGHT PROP ?

BILLIUM
I have the exact plane and engine combo you have way it sounds. DC F-20 OS FX46 with pipe. Been so long ago that I got this. but I think the pipe is a Mac pre-tuned for this engine, didn`t have to cut it or anything. I get very good speed, dont have a clue to actuall mph, would only be a guess. Allways think it should go faster though, lol Best prop i come up with is 9x8 either APC or I have a Zinger 9x8 speed prop someone gave me, works well also. I get between 15,000 and 15,500rpm depending on weather conditions.

Gregg,
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Old 10-15-2005, 09:30 AM
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Default RE: DC F-20 RIGHT PROP ?

700ft long runway and making a pass in 6 seconds from one end to the other

700ft div 6 = 116ftper sec

116 x 60 x60 = 419999.97

419999.97 div by 5280 = 79mph


That 60 x 60 thing is 60 sec in a minute and 60 min in an hour

We just use a simple stop watch so their is a bit of error but its close.




ORIGINAL: BILLIUM

DON'T UNDERSTAND ?
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Old 11-19-2005, 09:58 AM
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Default RE: DC F-20 RIGHT PROP ?

All,

It's been a while since I've been to the universe but I am glad to return with my usual assortment of speedy projects. I recently purchased a DC F20 and need to locate the CG for balance. I looked at the plans and it is indicated to be at 5-1/2" from the square edge of the wing center as verified by ruler on plans. Can anyone here suggest where they took thier balance pont?

Much thanks!

Rev on...............[>:]

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Old 11-20-2005, 02:01 AM
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Default RE: DC F-20 RIGHT PROP ?

not sure if your still looking for a good prop to use. If you have a lot of runway try using a pylon prop. 8.75x9 is what i use, cut down to a 8.5x9. I have a 600ft runway and it does take atleast half of it to get off the ground. This is one of my favorite planes to fly thanks to my brother. He built it up and glassed it for me. engine is a jett 50 with the needle at the carb.
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