Frequently Asked Questions

Have questions about RCSpeedo?  Click on any of the toggles below to learn more!

How can I test RCSpeedo at home?

You can test RCSpeedo with any computer equipped with speakers. Given adequate audio quality, RCSpeedo works equally well with recordings of EDF jets as it does with the real thing.

We suggest you use the video below to test your copy of RCSpeedo:


You should get speed detection for the majority of the passes in this video. If you are having issues with this, please contact us at Please include information on what phone or tablet you are using, along with any information regarding custom ROMs or operating systems.

Is there a trial version of RCSpeedo?

Due to iTunes restrictions, we needed to name the ‘trial’ version of the iPhone version a different name. It can be found here.  Unfortunately, due to restrictions on the Google Play Store, we were forced to remove our Android trial version.

The trial version locks out after 7 days so please download when you are ready to test it!  Please be aware that these versions will require a data connection in order to operate.

What’s the difference between the Android and iOS versions of RCSpeedo?

The iOS and Android versions of RCSpeedo are nearly identical. They both listen through the built in microphone of your phone or media device and automatically detect the speeds of passing model airplanes.  The only differences are aesthetic – the user interface is slightly different to coincide with standards for each operating system.

Will my plane work with RCSpeedo?

RCSpeedo was developed to detect passes made by airplanes that have at least a two-bladed propeller or impeller spinning at over 40,000RPM. Because of the nature of the acoustics emanating from spinning blades, ducted fans or props with three or more blades can spin at a lower RPM than 40k and still be detected. Generally speaking, the more blades and the higher RPM your plane has, the better (and more accurately) RCSpeedo will be able to detect your aircraft. An important consideration for some planes is also the amount of noise they generate. If you would describe your plane as ‘quiet’, there is not a good chance that RCSpeedo will work for you. Remember: the application works by listening to the sounds your plane makes, and if it can’t hear your plane, it can’t do anything!

If you don’t know if you meet these requirements, we recommend you get a sound or video clip of your plane flying and try running it through a trial version before you purchase the app.

My plane meets the specifications above but RCSpeedo still doesn’t detect it!

Even with the correct plane, RCSpeedo depends on the right conditions to work properly. Here are some ways you can increase the chances of detecting passes:

  • Reduce ambient noise.  Talking, other planes, music, wind, etc. will make it very difficult for RCSpeedo to get detection.
  • Speed passes must be made at a relatively low altitude, nearby the device. If you cannot distinctly hear the noise change in your plane passing, chances are that RCSpeedo cannot either and will not detect a speed. For faster planes (>100MPH), it is actually recommended that you make the pass further out from you as at close range the Doppler shift occurs too fast for RCSpeedo to detect.
  • Your speed passes need to have a distinct approach and departure time so that RCSpeedo can detect and follow your plane. What this means is that you need to line up your pass from one side of the field so that you are flying straight at full speed for at least 2 seconds before you make the pass, and you must continue holding full speed for another second after you have made the pass.
How accurate is RCSpeedo?

The answer to this question depends on many factors:

  • How much ambient noise there is (less is better)
  • The speed your plane is flying
  • The RPM your prop/impeller spins (higher is better),
  • How you make your passes (straight and level yields the best results)
  • How accurate the temperature reading you’re using is.

Generally speaking, clever folks in the RC industry have determined that the Doppler method, when used correctly, is as accurate as most consumer radar guns. In development, we calibrated RCSpeedo to the Doppler method promoted by these enthusiasts and in our experience, the program has never generated an accurate reading with an error of over +/-3 MPH for the 0-100MPH speed range, or +/-5MPH for the 100-200MPH range. Please note that occasionally RCSpeedo may make inaccurate speed detections (for instance, due to a pilot throttling down immediately following a pass), and these should be disregarded. If you have a 50MPH plane and RCSpeedo says it’s going 120MPH, RCSpeedo is wrong and you should make another pass! We would like to note that those constraints of +/-3MPH and +/-5MPH are WORST case and on average RCSpeedo is within 1MPH of your speed! If you want to get the most accurate idea of how fast your plane is traveling, our best advice to you is to get multiple passes and see what the average is!

How do I know if the app is working?

The iPhone and Android apps have indicators that tell you when the app is listening for speed runs. If you would like to see if your copy of RCSpeedo works, you can use the speakers on your PC and browse to this YouTube video with your app in listening mode:


You should get 4 or 5 speed detections from this video in the 45-70MPH range.

What are the different modes and which one should I use?

The different modes configure the app to better detect the speeds of “special” aircraft. If you are having trouble getting RCSpeedo to detect the speeds of your plane, you may want to try some of the modes besides ‘default’:

  • Default Mode – The standard mode that should detect most speeds. It also has the lowest probability of reporting “bad speeds”, which sometimes will occur when you blip the throttle or more than one plane is in the air.
  • 100MPH+ Mode – This mode better detects high speed planes, but will not detect passes under 100MPH at all.
  • Fast Pass Mode – This mode is for making passes with limited airspace, where you will not have the full ~2 seconds of full throttle required on approach. This mode will pick up significantly more “bad speeds”.
I still have questions…

No problem!  Please feel free to email us at  We will try our best to answer any questions you have.