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

Ducted fan engine with prop

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Old 12-18-2002, 05:37 PM
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aerowolf
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Default Ducted fan engine with prop

Presently considering the use of a ducted fan engine in a 40 sized warbird as an attempt to reach "extreme speed". However, don't have any experience with a DF combined with a prop. If it is a good idea, then what DF engine would be best, OS 91, Rossi 1.05 etc? Was considering the Rossi 1.05 with its big advertised HP of 6.15?

Presently I'm running a YS 91 and 120 FZ in a modeltech ME-109 25 sized warbird (this plane in upgraded strength wise from stock) and achieveing upwards of 150mph according to my Jet pilot friend who's plane is fully loaded this telemetry equipment.

Was hoping that the DF in a 40 sized bird would break 180mph?

Any thoughts?

Thanks,

Rudy
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Old 12-19-2002, 03:28 AM
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Default Ducted fan engine with prop

Any pic's of that 109? I'd love to see it.

I have the Global 25 sized 109 with a 40 in it. Even with that much motor it is a hoot. I couldn't imagine it with a 91 or 120 on it. How'd you balance it?
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Old 12-19-2002, 07:30 AM
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Default Ducted fan engine with prop

you have a .25 size and want to put a .91 DF on it?

they do make .21 size engines with a some extreme rpm's and HP. Rossi makes them.
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Old 12-19-2002, 01:25 PM
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Default ????

Originally posted by Aerowolf

Presently I'm running a YS 91 and 120 FZ in a modeltech ME-109 25 sized warbird

Was hoping that the DF in a 40 sized bird would break 180mph?

Rudy
Are you kidding?

George
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Old 12-19-2002, 04:06 PM
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aerowolf
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Default Extreme Speed

Originally posted by AQ500
Any pic's of that 109? I'd love to see it.

I have the Global 25 sized 109 with a 40 in it. Even with that much motor it is a hoot. I couldn't imagine it with a 91 or 120 on it. How'd you balance it?
Have some film that needs to be developed. When I do I'll be happy to scan them in a e-mail you, please email for my record. Was also planing to send them in to AMA magizine.

To balance, I opened up the rear bally of the fuse and placed all component sthere. Two standard servos, reciever, and battery. The horizontal tail is ribbed so I sheeted it with 1/32 balsa and between the rib voids placed 1 and 1/4 sticks of lead for the 91 and 2 and 1/4 sticks of lead for the 120. The 91 weighs just a hair over 5 lbs, the 120 weighs about 5.8 lbs. The 91 does about 140mph, the 120 does about 150mph. The trick to making the 120 move is the replace the stock 120 cam gear with a cam gear from a 91.

Thanks for the reply.

Rudy
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Old 12-19-2002, 04:33 PM
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Default Extreme Speed

Originally posted by George


Are you kidding?

George
This is a serious matter! I recognize that many people don't believe in these two set ups of mine. I know this because I've told several people at my local flying fields what I will be bringing to fly soon and their response is usually, WHAT? Then when I visit the field with my birds these same people can't believe there eye's even though its right in front of them. Then, when flying they all stand around waiting for the wing to break off, but it never does. This is after I've told them that the wings are not stock, they have been reinforced with carbon fiber on both the top and bottom of the spare and additional shear ribs have been installed, and they are rock solid. For some reason they don't hear any of this and are convinced that the wings should buckle.

Thanks for the reply,

Rudy
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Old 12-19-2002, 05:36 PM
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Default Sounds good to me.

Rudy, thanks for clearing all that up. It sounds like you have all the bases covered. I know if some guys I know did this, it would be disaster .

I'm sorry if I offended you, but my response was exactly what you said you encounter at your field. Great to see you have done it right, after all this is the EXTREME forum and you have an EXTREME set-up.

Let's see those pics when you get them .

Thanks,
George
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Old 12-20-2002, 01:29 AM
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Default Ducted fan engine with prop

if you are in the speeds of 150 or so I would really consider some more powerful servos than just standard. Especially after you had to add weight. Anyhting faster than that will just lay your control surfaces down or just have very little effect at WOT.

I first off tried some standard servos in my DD. They worked fine with my OS .46. After I installed my GRRT .40 I noticed that i needed more power from the servos. At half throttle they were OKAY i guess. At WOT. I had to give full stick to make a turn. The response was terrible and needed to be upgraded.

So just an idea to think about the other things as well besides what engine has more power. Would hate for that 150 MPH beast to hit the ground due to a servo failure.
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Old 12-20-2002, 03:40 AM
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Default Ducted fan engine with prop

Ive flown the O.S VFDF .91 in a 40 size Shrike with a 10x10 apc works really well for this engine
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Old 12-20-2002, 03:41 PM
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Default Extreme Speed

[QUOTE]Originally posted by FlooredCOBRA
[B]if you are in the speeds of 150 or so I would really consider some more powerful servos than just standard. Especially after you had to add weight. Anyhting faster than that will just lay your control surfaces down or just have very little effect at WOT.

Thanks for the advise. At 150mph in my 25 sized birds the standard servos work great. In fact to date these two birds are my best flying planes. Very smooth and responsive. However, if I do find a set up that will allow me approach 180/200mph in a 40 sized warbird, I did plan on using digital servos, probably multiplex.

Thanks for the reply,

Rudy
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