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Thread OP
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Question
Does anyone know the world speed record for an electric model?
From the FIA website it looks to be this one
Category F5: Radio Controlled Flight Sub-class F5 Open (Aeroplane, Electric motor COMB (all sources of current)) N°196: Speed : 274.28 km/h (about 170mph) and set in 1998 This is before GP and IB batteries and when LiPo's were a glint in some chemists eye. Any recommendations for power systems and plane that could beat this? I fancy my name in lights! Thanks John |
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There have been many faster unofficial speed runs than that record....several over 200mph. An official FAI record is a fairly involved set up from what I understand. But you're right, that's not a tough one to beat if you set up the equipment.
Another thread: https://www.rcgroups.com/forums/show...ght=fai+record |
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Last edited by Troy; Sep 21, 2006 at 09:59 AM.
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Radar guns don't count--the plane has to fly 200 meter line between two points flying level--both ways. Not the same as catching a sloper in a dive doing dynamic soaring. Steve |
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gps for speed records
Is the sampling rate of onboard GPS's like what Eagle Tree offers sufficiently close enough to record accurate speeds? I watched a show on TV where guys were firing model rockets to insane altitudes with onboard GPS units (didnt say what kind) but they were plotting their trajectories with what looked like reasonable accuracy for their record purposes.
http://www.eagletreesystems.com/Plane/plane.html Found this interesting link. Clunky looking GPS transmitter, but oooh! look at the multi-model trajectory course overlay software interface. Finally, an F5B/F5D toy for those who cant afford their own dedicated personal courseworkers for practicing! http://www.rebelrocketry.com/assets/...5170dbeb64.htm http://www.rebelrocketry.com/assets/...5170dbeb64.htm |
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ptxman,
GPS can have very large short term velocity errors. Chuck |
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Regarding accuracy in space for example, at 300 km/hr the model advances 83 meters per second. If a GPS is 'good' to within 5 meters (I havent got a clue about this actually) it would be 'out' by 5/83=6%? Not very good for official records but pretty good compared to radar gun vagaries, no? But with a steady stream of signals at say 0.1 second increments (or whatever these units are set up to do) that wouldbe 10 data hits over this same second, so you would think some averaging algorithm could smoothen the raw data for a representative average velocity no? |
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For non military users, GPS typically only have 10m precision at slow / idle speed and it should get worse at high speed. Without the commercial restrictions set by militaries, it's probably more like 1-2 m accuracy depending on # satellites catched.
However in reality a differential between two points at a given speed with lots of samples is probably representative, but tolerances (and FAI definition of the record & associated measurements) would not make results valid. |
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ptxman,
The biggest velocity error happens when new satilites come into view. That can happen for example when an airplane manuvers and the antenna sees a new satellite. The position solution of the plane can jump instantly to a new place if that happens. Thus the high velocity error. Yes it can be smoothed by software but the small devices that will fit into our planes are not that good. In sophisticated applications for aircraft the velocity is essentially smoothed by software and the inertial navigation system. For short term inertial navigation systems are much better than GPS for measuring velocity. They won't fit in our airplanes though. Chuck |
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speed record timing
Thanks guys, very informative about GPS's.
How about this concept for a speed gate. You have 2 identical, highly accurate digital display clocks, 2 video cameras & 2 sighting pole systems similar to F5D/B. The clocks are synchronized, each camera setup is positioned a known distance apart from each other and so each respective clock & sighting pole are in view & being recorded. The model flies through & of course must be in view. The video is played back to yield the enter/exit times & with the differential you calculate resultant speed? |
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Steve |
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Not accurate enough for world records, but you can do something similar with 2 guys and 2 stopwatches. Have the first guy at the start of the trap click his watch as the plane passes and leave it running. Have the guy at the end of the trap do the same. Bring both watches together and have one guy click both to stop them. Take the difference in time and work out the speed. There will be a little human error, but with several passes you can get a good ballpark idea, especially if the trap is long enough to minimize the error of clicking the watches.
We also tried shooting a gun as the plane passed each end of the trap for the "pop" to be recorded on the video camera we were flying over for doppler measurements. A little lag due to the speed of sound and again the human error of pulling the trigger at exactly the precise moment. The test plane was destroyed before we got any meaningful results on this method |
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