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

skyfire?

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Old 12-13-2002, 12:06 AM
  #1  
superdave118
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Default skyfire?

does anyone have the skyfire from radical rc? does anyone have any information on this plane? how fast would it go with a .46. would it hurt to put a .61 that i have lying around in it if i beef up the frount? which would be faster the skyfire or the diamond dust. if i put a .61 would it outrun the dust? does it have landing gear? if anyone has any comments i apreciate it alot.

thanks
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Old 01-03-2003, 12:17 AM
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Default skyfire?

I have a skyfire 40 that I just finished on Monday. The kit I built mine from was an older kit - kitted by a company called Four Pi. The kit was a breeze to assemble. I 'bashed it' in so much that I added seperate servos for each of the ailerons and a second vertical stab. I just didn't like the looks of that one big ugly fin - yuk!

I hope it flies as good as it looks. I will most likely maiden it this weekend.

I have no idea how fast it will be - but I am running an O.S. 46fx with stock pipe and a 10X8 prop.

Yes the Skyfire 40 has landing gear.

I can only assume the diamond dust would be faster - as it's newer and mostly composite ( I think..)

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Old 01-03-2003, 01:00 AM
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Default prop selection

That 10x8 is way too much most likely. Take a 9x7 with you and try both.

BTW. The diamond dust is mostly air. Six ribs and a couple pieces of carbon fiber spars.
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Old 01-03-2003, 01:57 AM
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Default skyfire?

the skyfire is the holy smoke reincarnated. with a 46fx and an apc 9x7 it could keep up with a comparable dust. i built two about three years ago and my brother is still flying one while the other is waiting.---henry
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Old 01-03-2003, 06:27 PM
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Default skyfire?

Thank you soo much for you input - this is going to be great!

I am new to this whole speed delta thing, so I asked around and was told that a 10 X 8 was the ticket for the O.S. 46fx - So I purchased two of them (APC). I don't own any 9X7's so I guess it's back to the hobby shop. I also wound up getting a few 11 X 7's just to putt around and get used to it. I can use them on my Super Sportster as well.

When you say the 10 X 8 will be 'too much' - what do you mean? Will it physically damage the motor? or will it be too hot to handle?

I don't want to get it going too hot as I would hate to loose this plane due to Flutter. I am using Futaba 3004's for each aileron and one more for the elevator. Granted the 3004's aren't the best servos for speed runs, they are all I have. I didn't use any of the supplied linkage - I switched to 4/40 rods for everything just to be safe. I also plan to seal underside of the hinge gap with monokote. If the 3004's are not going to be able to withs and the 10 X 8 (or 9 X 7's) then I won't use those props, I will just stick to the 11 X 7, and 11 X6's that I currently have. No sense ruining a nice model due to improper hardware! What are your opinions on this subject?

The plane came in just over 4lbs 5oz. (that's with 5 - 3004 servos, and extra vertical stab, and an empty 10oz Sullivan tank.) The advertised weight was 4lbs - so that's not too shabby!

I hope it flies well. Right now (with an empty tank) when I test the CG at the recommended location the plane come in just a tiny bit tail heavy. Because the tank is forward of the suggested CG when I add fuel the plane comes in nose heavy - should I worry about this?

I have flown Sport planes and Trainers in the past so again - this Delta thing is new to me. The only Delta experience I have is with my Zagi 400x. What kind of flight characteristics should I expect?

Thanks again for your info!
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Old 01-03-2003, 08:03 PM
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Default prop load

prop load has been discussed here in great detail. read thru some old threads. You can "search" for them.But briefly the 10x8 will be too hard for the engine to turn in the rpm range you need to get good power output. The variables you need to consider are
1) more diameter= more thrust
2) more pitch= more speed
3) more prop load= less rpm (and maybe less thrust and less speed.)
4)prop load = diameter cubed * pitch (d*d*d*p)
I have posted a web site that calculates these for you in an old thread.
Also you can cut down the props you have to get desired effect. Make sure you rebalance them.
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Old 01-03-2003, 08:29 PM
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Default skyfire?

oh - one more question.

The plans or manual didn't list any suggested throws for the ailerons or elevator.

Any suggestions would be greatly appreciated.

Thanks again for all the info,
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Old 01-06-2003, 05:23 AM
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Default skyfire?

I flew it today. It flew GREAT.

I picked up a tuned pipe at the swap meet. Will put it on next week and see if it improves the speed any.

Thanks for the tips on the prop. The 9 worked better than the 10.

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