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

Fast combinations!!! IDEAS WANTED

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Old 05-29-2003, 03:12 PM
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MR Flyer57
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Default Fast combinations!!! IDEAS WANTED

Hi everyone,
I am interested in your opinion of engines. What do you use to make your ships go fast and what would your dream motor be?

Do you have a brand favorite, or just use ducted fan engines?

Also what props do you like and where do you get them.

I am sure that there are a lot of different ideas floating around and no one will live long enough to try them all.

Do you have a muffler that is working well on an engine? I would like to hear about the combo.

Have you ever ported an engine and had success? Worked with compression, changed carbs, or mixed better fuel? Or is your trick in the glow plug,,,,,?

Please write about any combinations that didn't work out, you know, things to avoid.

I am hoping to get a working list of equipment to look for when I am on the hunt for speed.

Thanks and check back often!!
MR Flyer57
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Old 05-29-2003, 04:17 PM
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dusteater
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Default Fast combinations!!! IDEAS WANTED

ducted fan delta!
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Old 05-29-2003, 07:27 PM
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Gricey
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Default Fast combinations!!! IDEAS WANTED

Hi MR Flyer 57,

Just thinking about this today... I'm keen to build a engine test / run in bench to do some testing on my donks.... will build it with a sliding mount base and attach to fishing scales to get a reading on lbs thrust and a tach for rpm and it should provide a good baseline to test different prop / plug / fuel / combos on different engines. Will try to get it up and running in the next couple of weeks. In the meantime, has anyone built anything like this? post pics if you have.

I have some design ideas but don't know if I'm heading down the right track, if there are a few invented wheels out there let's see them.

also, is there a mathmatical correlation between static thrust and dynamic thrust or is this too dependant on model weight/drag etc..?
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Old 05-29-2003, 07:28 PM
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Gricey
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Default Fast combinations!!! IDEAS WANTED

btw, if you want cheap speed go straight for a Magnum with West Eurotech motor...

cheers,

Geoff.
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Old 05-29-2003, 07:53 PM
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MR Flyer57
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Default Fast combinations!!! IDEAS WANTED

Hi Gricey,

A test stand with a measure for lbs of thrust is a great idea, but I have heard some say it will only be a rough idea of the power. I think their idea was that when the prop unloads at speed, you will get a little different power and speed than while it is tied to a test stand.
I for one think that a test stand like the one you describe would be of great value. It would give you at least a starting point for pipes and props with an engine.

Great comments, and please post any pics of things fast!!
A picture of a magnum would be great.
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Old 05-29-2003, 08:11 PM
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Gricey
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Default Fast combinations!!! IDEAS WANTED

Hi MRF57,

yes, that was my comment on correlation between static (stuck to a bench) and dynamic (belting) through the air. I would suggest though that of the 2 static would be the hardest on the engine and more likely to show any 'useful' gain in power. Just think a 5% gain in static could turn out to be a lot more in Dynamic and should do in any manouver other than a prophang. I guess though, you could do some hell tuning mods that don't do anything for you on a flat but will catapult you in a dive which is what we all do to go for a high speed run anyway (sort of like how you can go much faster on a push bike in 12th gear down a hill than on a flat). I guess with more static thrust though you would be less inclined to loose the speed once you've flattened out of the dive (is this terminal speed, or is that when the plane flies to bits it's going so fast?) hmm.... any propeller heads out there to work this one out?

I wonder also is Static and Dynamic thrust max points dependant on a rev range and loading of the prop, I would assume so. Here's a test from the car world (full size not r/c) ... to find maximum torque rpm of your (naturally aspirated) motor, drive along in 3rd (or second if it is under 2000cc), choose an RPM (say 4,5000) back right off the gas, then floor it , really hit in to the floor hard, at the point where you car does not really lurch forward with any gusto you have found the point of maximum torque. If you do the test above and it lurches, try it at 5.5K then 6.5K, you should find some point (besides the rev limiter) where the car just feels flat. Slightly below that is maximum torque, maybe this is similar to maximum static thrust on a prop engine. Maximum HP is between 1.5 to 2.5k higher rpm than maximum torque, I wonder does this correlate with maximum dynamic thrust..... I guess only the test bench will tell us. Will have to get building! :-)


There's a pic of my Magnum in the Avatar under my name, and you can dl a movie (6mb) of my Magnum here -

http://www.rcsites.net/trd22/Movie.wmv

Picture quality is pretty poor, this clip was originally 25mb (with Satriani on the side) but it was just too big for Inet dl's.

regards,

Geoff.
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Old 05-29-2003, 10:37 PM
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Hey Gricey..

Terminal speed, or "Terminal Velocity" is when the speed takes the plane apart..

Wouldn't go there...
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Old 05-30-2003, 06:22 AM
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Default Fast combinations!!! IDEAS WANTED

that stand would work great for 3D planes finding out thrust pulls.

But for a speed plane with a speed prop finding out thrust may be different. Usually speed props do not produce as much thrust but create a higher speed. But this would be good to finding out thrust for launching the beast in air.

I know we use a fish scale at the field and anchor it to plane with a small rope and hold the scale. It gives to you idea on the thrust with weight of plane with it.
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