rcflyers

has anyone ever made their own?
where can i buy it?

Flipper

My Feedback: (3)

I got a Bushnell Speedster speed gun that will measure from 6 to 200 mph + or - 1 mph and if you hold the trigger down the digital reading will be in real time, if the plane slows the gun will show it. It was made for clocking base ball pitches or race cars but will work on anything. When you let off the trigger the display shows the speed when you let off. Uses 6 AA batteries. Check around, the cost should be under 175.00

Noflyzone

The speed trap we use at ACM is made by r/c model research in Odessa Texas. I do not know if they still make them or not. I have the phone number, but not in front of me. Let me know if you would like it and I'll run it down for you.

Dan

Cactus.

My Feedback: (1)

i saw a pic of that AMC speed trap in another thread, looks exactly what we need.
my idea so far is along the lines of two sound traps, like camera triggers, attach this to a stop watch thats been played with to show MPH not time....

colbourne

Is there any tricks to converting the Mattel speed gun for speeds above 100mph ?
These are available very cheap ~$20

XJet

The Mattel gun is (unfortunately) pretty much useless for model speed measuring purposes -- I know, I've tried.

I've also pulled one apart and found that it's obvious why this is, they're using a *very* low power microwave source that just doesn't have the grunt to give the necessary range.

Right now I'm designing and building a radar speed trap for an upcoming jet meeting that's to be held here. I'm using a 10GHz gunn diode module feeding a horn antenna and with a PIC processor to convert the signals into a speed figure. If I get time I'll also set up low-power RF link so that the radar itself can be set in a convenient place but the display can be placed on the flight-line -- thus making sure that there's no need for anyone to stand in the path of the oncoming models. I'll probably include a computer interface as well in case people want to automatically log the speeds into a spreadsheet or database -- such as might be done for a competition.

If anyone's interested in something like this, it seems that the total cost will be under US$200 and I'm happy to share the design and software I finally come up with.

combatpigg

My Feedback: (3)

2 cell phones and a $5 stop watch work well enough for me.

Phil Cole

Another method is to record the sound of a flyby and analyze the sound for the Doppler shift as the model flies past the microphone.

A bit of web searching along the lines of 'Doppler shift RC speed' should turn up the programs that do the analysis. Here's a start http://www.rcuniverse.com/forum/m_50...tm.htm#5062317

MadScientist

X Jet,

I would be interested in seeing how that is all set up. Would you mind sending me the info? PM me if you get the chance with your contact info. Thanks

XJet

PM sent

XJet

Tested out the first part of the radar gun today and it works perfectly.

We were clocking full-sized aircraft at around 800 yards and gokarts on a track next to our flying field at around 150 yards.

So far we've got a 20dB horn antenna coupled to a 10GHz gunn diode-based module with a 2-stage JFET low-noise amplifier that feeds a signal into the logic/display board from a real cheap Mattel Hotwheels radar gun. The Hotwheels unit is only good for about 30 feet but with a proper microwave source, good antenna and low-noise amp we're getting great range out of it.

Now I'll set about designing my own logic and display system so we can measure speeds over 100mph (the current limit of the Mattel logic board).

I'd post pictures here but my upload privileges don't allow that -- maybe an admin can fix that if enough folks complain about it :-)

nitro junky

My Feedback: (3)

I just got a radar gun about a month ago. I took it to the field and even the old timers with the piper cubs were gunning for speed that day ( it was funny as hell ) This is the one I got it was relatively cheap and it works great. This was the first time I dealt with this vender and the service was fantastic. I would highly recommend them.

[link]http://www.opticsplanet.net/busspeedrads.html[/link]

huey-pilot

My Feedback: (17)

I purchased one of these about 2 months ago at Radio Shack, they were on sale for $74.95, the radar gun seems to work fine. I have been able to get the speed of an arrow (155mph) with the gun behind me about 5 feet. I am using it to improve my discus launch sail plane technique, I have someone hold the trigger down during the launch and the max speed is recorded when the plane is launched, the average speed at this point is 65 mph.

colbourne

This thread may interest the experimetal types out there :-

http://www.austech.info/showthread.p...ghlight=mattel


It describes how to upgrade a Mattel Radar gun by adding a more powerful gunn diode.

These diodes are available for about $5 and with the Mattel Radar gun costing less than $20 you can build a cheap radar.

Cyclic Hardover

My Feedback: (3)

I use a simple calculator, 1st grade level math and a stopwatch.

JohnRC

I've owned a Bushnell for 8months. We can get a speed responce from a large plane (80" or larger). The smaller planes are almost imposible to get a reading. Can't stand in the middle of the runway, saftey reasons. Has any one tried to modify the bushnell with a bigger horn?

Thanks
John

colbourne

It should be possible to modify the Bushel with a more powerful transmitter (gunn diode ) or to some how make the receiver more sensitive either with a better wave guide or an amplifier.

hooty301

I use a Garmin GPS to measure speed on my boat, it only weighs 5oz's and is very accurate. Dont know if this would be to bulky or to much weight for you or not. I place it right on the center of the balance point and you cant even tell its there.

JohnRC

Hooty301, which model are you using? and what is the max speed it will display?

nitro junky

My Feedback: (3)

I have got the speed of a sig wounder and your right the only way to do it is in the middle of the runway. It worked, We got around 117mph out of it.

hooty301

Its the 12 channel etrex,not sure what the max speed that it will display. Ill have to find out for you.

Easystern

I use a garmin etrex and a bushnell velocity for79$ , the bushnell is good on planes around 100mph ,i did try the gun on 160mph planes (2stroke) and i didnt get an accurate reading.

the etrex is perfect , i bought it actually for my jet ski http://www.garmin.com/products/etrex/

i am thinking about to get a speed device/dataloger from eagletree http://www.eagletreesystems.com

GLbiggles

This link does not work for me. Can you provide the information? I'd like to try the mod on my gun.

Crazy4Flight

My Feedback: (540)

I just wait for the SONIC BOOM then I know I am going fast!

BillS

A Garmin was used to measure the speed of several turbines over the weekend.

Bill