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

Modified Mach Racer

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Old 11-03-2007, 03:29 PM
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Ed_Moorman
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Default Modified Mach Racer

This is the first 2 test flights of my second Mach Racer.

Modifications to stock kit:
1. Landing gear and nose wheel steering servo deleted
2. Elevon servos moved to top of plane.
3. Fins reshaped and rudders added.
4. Dual rudder servos added in the hatch area.
5. Titanium pushrods on the elevons.
6. All digital servos.

Engine: OS .50SX

Flight #1: Trim and control feel flight
Stock muffler
APC 11-5 prop
Omega 10% castor blend fuel

Take off from launcher very nice and stable. Plane needed some left aileron trim. One elevon was warped. Handles very nicely. I am using a lot of exponential on all controls. Landing is good in the grass.
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Old 11-03-2007, 03:39 PM
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Ed_Moorman
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Default RE: Modified Mach Racer

Mach Racer Flight #2

For flight #2, I changed the following:

Muffler: Jett Stream tuned muffler
Prop: APC 8.8-8.75 pylon prop

On the first try, the plane settled to the ground before it gained flying speed.

I cranked again and this time held a good amount of up elevator. The plane dropped again and skimmed the grass, but kept going. Once it got "on the step," it was fast. We don't know the exact speed, but it was moving compared to the stock muffler and 11-5 prop. I had tested the Jett on the bench and gained around 1,700 rpm.

Even though the plane was faster, it was still stable and easy to control. You do not look away from it or fly too long before turning. It's gets away very quickly.

It seems evident that if I want to continue to fly the high pitch props, I'll need some kind of bungee assisted launcher to preclude descending into the ground on some flights.

Bottom line: It's a good little plane. It's very stable and easy to handle for sport fliers. I am sure it flies well with the landing gear and is still pretty fast. Losing the gear will gain at least 15 mph, I would think.

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Old 11-03-2007, 04:28 PM
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Kmot
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Default RE: Modified Mach Racer

Try Cobratraxxas' launching dolly.
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Old 11-04-2007, 03:04 PM
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rmenke
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Default RE: Modified Mach Racer

Ed:

Thanks for the report, interesting. I have acquired two of these things from club members who thought they were just too much for their pilot skills and wait their turn in the production schedule. One of the things holding back completion is the development of a decent launch ramp and the resurfacing of our club asphalt strip. Saw a interesting launch ramp last year, but have not found it again. Will search for Cobratraxxas per Kmot and see what comes up. The ramp design is basically easy, something to keep both tractor and pusher designs streight seems a little more complicated. Yea, there is also a multiplex "Fun Jett" with the 150 mph + setup waiting. Just had to build something electrc that the club gang may appreciate. I know the "Brotherhood" would get a kick out of the thing. Too many projects, too little time Enjoy, bro 119
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Old 11-04-2007, 09:31 PM
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Default RE: Modified Mach Racer

Here is the thread:

http://www.rcuniverse.com/forum/m_41...tm.htm#4149904

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Old 11-05-2007, 03:46 PM
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Default RE: Modified Mach Racer

Excellent report Ed......

Im pleased the project turned out well.

Good example here also of a lot of what we have professed in the speed forums. The prop and engine selection have to be matched to what the engine is capable of, the aircraft, and your performance objectives.

Btw... try a standard blade APC 9x8 on that setup if one is available. More blade area than the racing prop, rpm should be up there still, and it will unload in flight. Might launch a bit better. Seems to be the prop of chouce for Jett 46/50 power on the delta aircraft for the best all-around performance. Should work well here too.
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