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

How we clock our Planes

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Old 12-26-2007, 10:23 AM
  #1  
JohnRC
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Default How we clock our Planes

We found this to be the safest and easies way to clock the speed of our planes.

I use a Robic SC-554 stop watch. You can program in a distance between two points and it will auto caluate the MPH.

We measure a 300ft distance in the safe area off the runway. One person is the signal person and one person runs the stop watch.
I found a high dive down to the signal person and level out over the runway slows the plane down. A dive down then level out some distance before the signal person gives the best speed.

We tried radar guns, could not get a shot of the plane. Not smart and not legal to have a person in the middle of the runway.

The sound method required to much equipment.

Hope this helps anybody out trying to get some sort of speed caluations on their planes.

JohnRC
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Old 12-26-2007, 11:37 AM
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Mike Connor
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Default RE: How we clock our Planes


ORIGINAL: JohnRC

The sound method required to much equipment.
An accurate time will give an accurate speed. Nice looking stop watch.
The Doppler method only requires a sound file and a free program. I am going to record a speed pass on my cell phone next time out to see if that works ok.
Nothing wrong with using two methods to verify the speed.
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Old 12-31-2007, 12:23 PM
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Default RE: How we clock our Planes

what program do you use ??????????????????????????
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Old 12-31-2007, 12:50 PM
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Mike Connor
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Default RE: How we clock our Planes


ORIGINAL: johnfly

what program do you use ??????????????????????????
You asked in the Sig Kobra thread and I answered there but here it is again.

http://www.sprut.de/electronic/soft/scope.htm
It is in German but I let Google translate the page.
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Old 12-31-2007, 10:51 PM
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Default RE: How we clock our Planes

Hey u guys just thought id tell u that myself and a few guys from my club have used a Garmin E trex GPS to get what we think are very accurate speeds. Tha GPS is about the size of a cell phone and will fit under most canopies. It has a max speed recall so as long as u dont put it into a long dive b4 your speed run it is pretty close.
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Old 01-02-2008, 06:44 PM
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johnfly
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Default RE: How we clock our Planes

thanks mike .......... sry for the repost
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Old 01-03-2008, 08:47 AM
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Default RE: How we clock our Planes

Garmin. That's cool.
"Turn left, no the other left."

Bill
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Old 01-03-2008, 10:47 AM
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Default RE: How we clock our Planes

you have to watch the Garmin gps check out this thread i had some problems with one i have also read a post in the jet forum with the same result that i had
http://www.rcuniverse.com/forum/m_67...tm.htm#6773202
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Old 01-03-2008, 12:19 PM
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Default RE: How we clock our Planes

The vertical measurement on almost any GPS is not very good. I would expect the sampling rate to be slower than desirable and in the half to one second range. With slow sampling turns would be measured across the corner. However if turns and verticals were slow and a 300 foot level high speed pass were made Garmin should give good results. When used understanding the restrictions it sounds like Garmin has the potential to give good information.

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Old 01-04-2008, 12:22 PM
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Default RE: How we clock our Planes

Here is a test that I did. I have a large, scratch built stick type plane powered by a Homelite 30cc conversion engine. It's not real fast, but is plenty big for hauling a payload. I strapped my Garmin GPS 12 to the plane. I set the GPS sample rate to the 1 second minimum. This will give the most accurate readings. I also placed a sound recorder in the middle of the runway to record the high speed, straight, level, low passes over the runway. This way, I have 2 different methods of annalyzing the speed of the same pass. Once back at home, the recorded flight track from the GPS is downloaded to the computer and using GIS software, I can overlay the path my plane flew with aerial ortho photos of our flying field. The speed at any point in the flight can be seen this way. This can then be compared to the Doppler method using the sound recordings of the exact same passes. The readings on the GPS were between 66 and 68 mph and the Doppler readings averaged about 1 mph faster. My conclusion is that both methods are accurate if done properly.
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Old 01-05-2008, 02:34 AM
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Default RE: How we clock our Planes

Get a real radar gun not a $100 radio shack bushnell gun. Stocker Pro or Decatur Pro Speed. Both of these guns can pickup a 28" span Speed 400 pylon racer way off the runway and dead accurate. You can clock bigger planes from way away. Most other methods are very error prone. Unfortuantely not the cheapest sollution as a refab Decatur gun is about $450.
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Old 01-05-2008, 04:55 PM
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Default RE: How we clock our Planes

I don't clock, I calander.

1st the number of days or months to build. [8D]
2nd the number of months left until flying season. [&:]
3rd the number of days or months to build it again! [:@]
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