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

first flights on DD-- need some thoughts

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Old 06-10-2003, 10:51 PM
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BAD ANDY
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Default first flights on DD-- need some thoughts

Went out for the first day of flying with my new Diamond Dust. Powered by a 46fx on a pipe. First flight was with one of my old pylon props 8.5x7 wood. Plane was fairly quick but I was wanting to get the flight package trimmed before I chased the speed. So I added to my control throws 3/8" low rate and 1/2" on high rate and I also dropped my expo from 85% to 60% which felt alot better on the sticks. The third flight I tried a APC 9x7, and at launch it seemed a little better as far as bite but seemed to fall on its face quickly and never really got up on the pipe at all. I had another APC with me (9x5) but I felt that would have not been worth while to try. So I went back to the original 8.5x7. I did not have a tach with me to check the revs. Sorry. What would your thoughts be to try on this engine. And the plan is to get all out of the 46fx that I can and then swap out with a reworked K&B ducted fan motor. Thanks for your input... BAD ANDY
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Old 06-10-2003, 10:55 PM
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BAD ANDY
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Default one other problem

Another problem I noticed was with fuel delivery after some burned off. It seems after about 1 oz of fuel is burnt off I have a fuel delivery problem in high G turns. Could this be because the tank is lower than the needle? I made several inverted high G turns and it did not seem to be as noticable but was still there. Or is my pressure fitting too far back on the pipe??? Things that make you go hmmm.. Thanks again, BAD ANDY
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Old 06-10-2003, 11:04 PM
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ChuckAuger
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Default first flights on DD-- need some thoughts

Hard to say..it's real hard to set a pipe properly without a tach..a lot of cut n try.

As for the fuel..the tank is probably a little low, also your engine might just be coming on the pipe and needs to be set a little fatter before you launch. Makes it a drag when you can't just land and set the needle and take right back off.

The best place for a pipe tap is about 1/4" ahead of the max diameter ( you have yours in the max diameter section) but I've seen them just about every place on the pipe and header and still work

I'd just try to set it a little rich before you launch next time and see how it does.

Plane looks swell!!
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Old 06-10-2003, 11:09 PM
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BAD ANDY
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Default your right

At the feild, STOMPER and myself both were saying the samething, this sure isnt like flying our profiles where you just land and tweek and take off again into a hover. I did notice in all the flights a very nice smoke trail. I had planned on the engine unloading after take off and tried to keep it a touch on the rich side. I will have my tach with me next trip out. Do you think I am in the baalpark as far as props go?? Later on, BAD ANDY
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Old 06-10-2003, 11:32 PM
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ChuckAuger
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Default first flights on DD-- need some thoughts

Yeah.. I think you are spot on with the props..in fact I have a buddy who built one with the same engine and the Macs pre-tuned pipe. I suggested he run a 9X8 and he did. It was moving right out when a radio failure ended his Dust. So I'd say you were right in the same ballpark!

And a piped engine will leave a nice smoke trail even if it's a little lean..I bet you'll be fine next time out.
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Old 06-11-2003, 12:21 AM
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Default Prop

I put about 40 flights on my Dust with a 46FX before I dropped a Jett FIRE 50 in it.

I played around with props quite a bit. The APC 9X8 sport prop seemed the best overall.
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Old 06-15-2003, 08:55 PM
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Default getting better

I flew the DD yesterday after some changes and it was alot better. I ended up with a apc 8.5x7 pylon prop (very thin and narrow blades) and it really got up on the pipe nice and stayed there.
The problem with high G turns was corrected by shimming the tank up 1/2" where the pickup was now centered threw carb. Problem solved. I will try a couple more props then the ducted fan engine goes on. Thanks, BAD ANDY
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Old 06-16-2003, 12:47 AM
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Default Re: one other problem

Originally posted by BAD ANDY
Another problem I noticed was with fuel delivery after some burned off. It seems after about 1 oz of fuel is burnt off I have a fuel delivery problem in high G turns. Could this be because the tank is lower than the needle? I made several inverted high G turns and it did not seem to be as noticable but was still there. Or is my pressure fitting too far back on the pipe??? Things that make you go hmmm.. Thanks again, BAD ANDY
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Look at things like this: when you are flying flat and level 1G is working on your plane... if your tank is 1" below your needle valve, and you pull 20 g's out of a dive, it seems to the engine like it has to draw fuel from 20 " below the needle valve... and that is a long way down...
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