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SPEED-GUN

Old 10-30-2009, 11:39 AM
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georgek54
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Default SPEED-GUN

Good Day to All Friends


I wonder if there is a speed-gun (at a reasonable price !) to measure combat-planes speed.

A friend of mine just bought GREAT-PLANES "Warhawk" and he contends that this plane with a .25 FX engine can reach a speed of 160 km/hour. Now, he intends to place a .35 SX to the plane and I am thinking of the speed that this "monster" could succeed.

A 200 km/h, more?

I have a poor "SICKLE" plane (wing) with a 25 FX and 1.15 kgr of weight. What could be the speed of this plane? Do I have any chance against "WARHAWK" ?


I think a speed-gun could help a lot.


Thank you in advance

George

Old 10-31-2009, 02:32 AM
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combatpigg
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Default RE: SPEED-GUN

To reach that speed a 6 pitch prop needs to turn faster than 18,000 rpm.
Old 11-01-2009, 12:25 AM
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Default RE: SPEED-GUN

Here in the States we just find a friendly polceman to see if he would check the speed on our planes with his speed gun when he gets off duty. Works almost everytime this way you do not have to buy one goodluck.
jerrysu29 Call Sign Wild Man
Old 11-02-2009, 01:00 PM
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MartyH
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Default RE: SPEED-GUN

Don't forget you need 4 times the power to double the speed. You can keep that in mind when taking wild hare guesses at a proposed change in power once you have a baseline measured speed.
Old 11-02-2009, 02:22 PM
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georgek54
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Default RE: SPEED-GUN

Thanks all friends


I just found Bushnell Speedster II radar speed gun at a terrific price, only 90 $.

The only thing that confuses me is that this instrument does not have any viewfinder to see the target (plane). At least it seems so, in the photo at the manufacturer's SITE.

Has somebody used this instrument? Do we have any info about it?


Regards

George
Old 11-09-2009, 11:30 PM
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Default RE: SPEED-GUN

Speed guns are very hard to use for clocking model airplane speed. We tried several types at my club for clocking the different classes of planes used in our racing class. They only way we could get them to work was to stand in the center of the runway with the plane flying towards us. There isn't a lot of metal in a model so we kept getting different readings or none at all. If you go into the extream speed prop plane forum they may know what guns work best but so far I haven't seen any one of the cheap guns that worked very well. Hope you have better luck then we did.
Old 11-10-2009, 12:23 PM
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Default RE: SPEED-GUN

Best to just use the Doppler speed program to find the models speed.

http://66.196.80.202/babelfish/trans...e.htm&.intl=us
Old 11-30-2009, 02:33 AM
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ddemu
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Default RE: SPEED-GUN

I've done quite a bit of radar work at club fun-fly events, and have found it pretty easy to do, but that's using a $2,000 radar unit.
Bushnell and others sell lower cost "speed-guns" for use with baseball and other sports. These should give acceptable results with R/C planes if you remember a few basic principles.

Unless you're using a laser type, the radar signals goes out in a cone shape so there’s no need for a viewfinder, just point and shoot in the general direction of the plane.

Limit the angle between the radar unit and the passing airplane as much as SAFELY possible. The greater the angle, the less accurate and lower the displayed speed will be.

The radar signal has to be reflected back to the radar unit in order to obtain a measurement. The spinning prop is the biggest target, but like most of our materials it's non-metallic so the entire plane is somewhat stealthy. The bigger it is and the more mass it has, the easier it will be to pick up.

Watch your background. If the radar "sees' something bigger behind or in front of the intended target, you'll see interference and have to interpret the signal in order to tell what's going on. Remember the cone shape: even if it's not in a direct line, the radar unit might pick up on a stronger reflected signal, bounced back by a larger object in the area.

I’ve successfully obtained radar results on everything from a 14mph all wood glider, to a 220mph turbine powered model and it's always interesting to see how inaccurate our own visual/mental estimations can be.
Old 01-16-2010, 04:45 PM
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asmund
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Default RE: SPEED-GUN

I have this inexpensive Bushnell gun and I think it is great. I get consistent readings at good distance and even my small and sleek Zagi Typhoon 430 (foam flying wing) with it`s minimal frontal area is no problem for the gun to read[8D] It is fun also to measure the speed of our boats and cars, all in all a very good and fun product
Old 01-16-2010, 08:11 PM
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ddemu
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Default RE: SPEED-GUN

I've seen a few others advertised at sporting goods dealers, but I think the Bushnell model is probably better quality. Others that are advertised to use for baseball and other sports may work just as well and may save a few dollars if the Bushnell model is more than your wanting to spend.

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