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35% Aircraft speed ??

Old 01-10-2007, 10:05 AM
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3Dreaming
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Default 35% Aircraft speed ??

What speed does a 35% scale aerobatic model fly at? I know it appears that the larger models are not going as fast as a smaller model, but I think that is an optical illusion. I would like real world numbers not guesses.This is for the purpose of servo torque calculations. Thanks, Tom
Old 01-10-2007, 10:25 AM
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bubbagates
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Default RE: 35% Aircraft speed ??

Tom,

You may find that not many are going to be able to give you anything but a guess. I can run some numbers for you on my prop software/servo torque software if you can tell me the engine size, expected prop brand, diameter and pitch and the engine rpm with said prop, expected weight, etc...

Old 01-10-2007, 11:14 AM
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Default RE: 35% Aircraft speed ??


ORIGINAL: bubbagates

Tom,

You may find that not many are going to be able to give you anything but a guess. I can run some numbers for you on my prop software/servo torque software if you can tell me the engine size, expected prop brand, diameter and pitch and the engine rpm with said prop, expected weight, etc...
You know I didn't even think to put the numbers to it, but a 10" pitch prop at 6500RPM would give you 65,000 inches per minute, or just over 60MPH at 100% efficiency. I just thought with all the telemetry type stuff someone would have some real numbers. Tom
Old 01-10-2007, 11:44 AM
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Default RE: 35% Aircraft speed ??

I remember a few threads that discussed speed. I thought 60 MPH is straight and level flight, about 90 MPH in a dive. These were all giant aerobats.
Old 01-10-2007, 02:34 PM
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Default RE: 35% Aircraft speed ??

A friends Composite-ARF 3.1m SX with DA150 and either a Mejzlik32x10 or Airmodels32x11 prop was clocked at minimum 99mph in a WOT straight and level pass. The speed trap only went to double digits, so how much, if any, over 99 mph, I don't know.
DKjens
Old 01-10-2007, 03:48 PM
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as722
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Default RE: 35% Aircraft speed ??

Last year my buddy clocked my 40% carden 330 at 98 mph wide open straight level flight and 113mph from a shallow dive at full trottle. It doesn't mean anything but it's cool to know.

Albert
Old 01-10-2007, 04:36 PM
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Default RE: 35% Aircraft speed ??

If you know someone with a Weatronic receiver with the GPS module it should be able to give you some speed and elevation indications. The generated log file gives you flight data of every flight. Of course you could invite a local policaman with a radar pistol to your field !
Old 01-10-2007, 06:24 PM
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Default RE: 35% Aircraft speed ??

I clocked my 35% Carden Cap with 3W 100. Using radar gun I get 90 mph into the wind and 100 mph downwind. Using menz 27x10 wood prop. I have just added a eagle tree telemetry system to it. I first put the pitot tube on the side of the fuselage (because its easy to mount there. It showed 115 mph but it is in the propwash so it will be high. Just yesterday, I moved it on to the leading edge of the wing, beyond the prop, but I have not flown it yet.

By the way, the rpm increased from 6000 on the ground to 7000 in the air. eagle tree also shows altitude and engine temperature and receiver voltage. very cool
Old 01-10-2007, 06:32 PM
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Default RE: 35% Aircraft speed ??


ORIGINAL: 3Dreaming


ORIGINAL: bubbagates

Tom,

You may find that not many are going to be able to give you anything but a guess. I can run some numbers for you on my prop software/servo torque software if you can tell me the engine size, expected prop brand, diameter and pitch and the engine rpm with said prop, expected weight, etc...
You know I didn't even think to put the numbers to it, but a 10" pitch prop at 6500RPM would give you 65,000 inches per minute, or just over 60MPH at 100% efficiency. I just thought with all the telemetry type stuff someone would have some real numbers. Tom
Tom,

I need the prop diameter then I can run the numbers and give you an idea.
Old 01-10-2007, 07:36 PM
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Default RE: 35% Aircraft speed ??

My buddy put a hand held GPS unit in his 42% Cap and it measured a max speed of 125 mph. There were no WOT dives ... normal IMAC type aerobatics plus a couple WOT level passes. Was way higher than any of us would have estimated. Can not confirm the accuracy ... it was a typical hand held GPS so was probably pretty close.

JS
Old 01-11-2007, 06:41 AM
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Default RE: 35% Aircraft speed ??

A few years ago, a police officer showed up at our field to watch us fly, and we convinced him to whip out his radar gun. There was a Kyosho Cap 232 with a K&B .48 glow motor in it that seemed fast and clocked about 82 mph. I was flying a 1/3 scale Extra then with a BME 102 and Menz 26x10 prop that visibly seemed slower than the Cap. In a straight and level full throttle pass, the plane clocked 92 mph. So much for the slow perception.
Old 01-11-2007, 07:28 AM
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Default RE: 35% Aircraft speed ??

Perception is everything, look at a Lear Jet or other small jet landing. It looks pretty fast and he's coming in around 120 to 130Mph, now look at a 747 landing, he is landing at roughly 150 to 160Mph (not knots) and it looks like it should be falling out of the sky.

That's an example that I tell all of the new GS pilots I run into that are having trouble landing because they see the plane appearing to move slowly on approach, only to find out it's really moving along and are gonna land long and pretty hot
Old 01-12-2007, 12:03 AM
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EddieWeeks
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Default RE: 35% Aircraft speed ??

Here is some real data with a video of the flight..



Video
http://www.variablepitchhobbies.com/...pitch_0001.wmv

Eddie Weeks
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Old 01-13-2007, 09:25 AM
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Default RE: 35% Aircraft speed ??

My AW 33% Edge with 3W-100 calculates to a little over 60 mph with a 27x10 prop turning around 6500 rpm. However, don't really know what the actual pitch of the prop is and can only take a guess at unloading in straight and level flight. A police radar gun showed 64 mph, which correlates.
Old 01-13-2007, 02:24 PM
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Default RE: 35% Aircraft speed ??

That sure seems slow to me,,i put a hand held GPS which takes off of 12 Sats,,in 2 different 35% TOC Yak 54's..both running 3w-106's average speed level flight,,110 to 112,,very very shallow dive,,125,,im guessing any kind of down line with any power,,your looking in excess of 130 or more..

NdFrSpeed
Old 01-14-2007, 12:01 AM
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Default RE: 35% Aircraft speed ??


ORIGINAL: 3Dreaming
This is for the purpose of servo torque calculations.
Sounds interesting. Are you trying to predict the occurance of flutter? Blowback?

Keep us posted with your findings.


I think our planes go faster then we think. Imagine this: You have a cut runway that's 600 feet in lenghth. If you bore on by at WOT from one end to the other and do so in about 3.5 seconds, you're doing a buck twenty. Not to hard to imagine if you think about it.

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