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Transolve AirSPeed Gage Max Speed Recorder Review

Mike Llewellyn looks at the Transolve AirSPeed Gage Max Speed Recorder. This stand alone air speed indicator takes the guessing out of how fast our RC models are really flying!

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Introduction


Dimensions:45mm x 20mm x 16mm
Range of measurement:14mph - 125mph
Readout:LED pulse - 1mph precision
Power Input:5v-12v
Input:Static port and Pitot tube
Battery (optional):12v
Weight:11g
Weight of stand alone battery mod:17g
US distributor:Transolve
AirSPeed Gage:ASPG-1.0 AirSPeed Gage
Price:$40

Like many of us, have you ever wondered just how fast your RC model was going? Some of us simply guess and others use radar guns to determine the speed. Both of those methods are not exact however. Now we can actually determine with FAA certified accuracy the speed of our RC models!

The AirSPeed Gage ASPG-1.0 is a small, self contained maximum air speed indicator built specifically for RC aircraft. Transolve also makes other nifty devices for RC and model Rocketry.

Contents

Included for review:

  • AirSPeed Gage
  • Stand alone battery system ($10 extra)
  • Extra battery
  • Jumper
  • Instructions

Key Features:

  • FAA certified for accuracy!
  • LED playback (flashes) for MPH readout
  • Rugged construction
  • 5-12v input
  • Light weight - use in nearly any plane
  • Use RX for power (connector included) - or separate 12v supply
  • 2 Year Warranty

Setup

The Transolve Air SPeed Gage can be powered by with any DC voltage source 5v-12v input. It includes a standard radio connector that can be attached directly to a receiver or to the stand alone 12v battery.

I measured the power consumed and found it draws about 10mA in operation. This low current draw made it safe for use with linear BECs included in our ESCs.

The instructions indicate that you will have over three hours of operation with the optional 12v battery.

Instructions

The Transolve Air SPeed Gage comes with a one page instruction manual. It is clear, concise and easy to follow and includes an email and phone contact for support as well - very nice.

Aircraft installation

The Transolve Air SPeed Gage came with a very short length of small diameter fuel tubing which attached to the "Pitot" nipple on the ASG and extended outside the aircraft for clear air pressure measurement.

The instructions indicate that you can extend the length of the tubing. This is important as you must get the pitot tube outside of the propeller arc or it will affect your speed indication.

It also includes a small, rigid plastic tube to act as the actual pitot. That was nice at it made attachment to the aircraft easy.

Also note that you must leave the static port (the other connection on the ASG) open inside of the model. Instructions indicate this static port must not be in airflow inside the fuselage as that turbulence would affect the measurements and accuracy.

Car testing

My first test was the Stick the Pitot Tube Out of the Car Window test. I wanted to see if the AirSPeed Gage matched my car speedometer, and I am happy to report that it did. In fact, it matched exactly in a number of tests and speeds. It was clear this unit would be accurate for detecting the speed of RC models.

Aircraft testing

I used the following airplanes in flight testing:

  • Alfa Spitfire
  • Park Zone T-28 Trojan
  • E-flite Taylorcraft

Alfa Spitfire

The Alfa spitfire had the following power equipment installed:

  • Skatty x400 brushless motor
  • TP 1320 3s pack
  • Atlas 18amp ESC
  • APC-sf 8x6 propeller

Full aircraft specs: Alfa Spitfire from Hobby Lobby

ParkZone T-28 Trojan

The ParkZone T-28 had the stock power system installed:

  • 480 brushless motor
  • ParkZone 1800 mAh 3s pack
  • Atlas 18amp ESC
  • Stock 9.5x7.5 propeller

Full aircraft specs: ParkZone T-28 from Horizon Hobby

E-Flite Taylorcraft 450

The Alfa spitfire had the following power equipment installed:

  • Park 450 brushless motor
  • Polyquest 1800 mAh 3s pack
  • eFlite 25amp Pro ESC
  • GWS HD 10x8 propeller

Full aircraft specs: ParkZone T-28 from Horizon Hobby

Here are some pictures of the installation in the Taylorcraft. As you can see it is very simple to tape on the pitot tube and install the unit in the fuselage.

Reading results

To start simply power up the AirSPeed Gage. This is confirmed by the LED slowing flashing about one time per second.

Then you fly!

After landing it was very easy to read the results. I applied the jumper to the two exposed tall pins on the board (you can also short the pins with a coin or key) which takes the unit from measurement mode to readout mode. It was only necessary to short the pins momentarily to turn the readout mode "on".

Once the pins have been shorted, the LED readout flashes. I simply counted the flashes, "one", "two", "three" etc., for the first indicator in MPH. There is a short pause, and the second readout number flashes. For example: If it flashes 5 times, then pauses, then flashes 6 times, your model attained the top speed of 56mph. Simple as that!

If you have gone over one hundred MPH it will flash and pause three times. So for 109 mph it will flash once, then one long flash (indicating zero), then nine times.

Speed test results

Speed Results
Aircraft Normal flight Dive
Alfa Spitfire 62 69
T-28 57 64
Taylorcraft 49 53

Conclusion

The Transolve Air SPeed Gage was very easy to use and setup. In car testing, results matched my speedometer. It was certainly "fun" to know how fast the planes were actually going. Results were very consistent in flight testing.

The Transolve Air SPeed Gage adds a great element of fun to the hobby and can be used for in-flight propeller testing and taking the guess work out of model speeds!

Pluses:

  • Small and light
  • Stand alone unit (with separate power system)
  • Easy to setup

Minuses:

  • Digital speed readout would be nice
Last edited by Angela H; Jan 15, 2009 at 10:32 AM..
Thread Tools
Jan 14, 2009, 08:02 PM
BEC
BEC
Registered User
BEC's Avatar
Does that T-Craft have any air inlets and outlets for cooling? For the static source the issue is pressure variations around the static port whether due to turbulence on the surface of the airplane (flush-mounted ports) or variations inside the fuselage that have nothing to do with the ambient air conditions (if the static port is inside the airplane). Cooling air inlets with no outlets would be a particularly bad situation as the "static" pressure would increase as you ran the motor up, leading to falsely low airspeed indications.

On the other hand, if the static port was near an area of low pressure then the airspeed would tend to read high.

Getting the static ports to read true ambient air pressure is a knotty problem even for full scale airplanes.

After all, the way this (or any other pitot/static airspeed indicator) works is by reading the difference between the dynamic air pressure at the pitot port - which should be in clear air and pointed straight in the direction of flight - and the static pressure at the static port then calculating the speed from the pressure differential.

That said, the numbers you report are plausible values so it looks like it was all OK.

Interestingly you picked just about the same spot as the full-scale Taylorcraft's makers did for the pitot tube. It's attached to the jury strut on a T-Craft and the plumbing runs down along a lift strut just as you have done.
Last edited by BEC; Jan 14, 2009 at 08:12 PM. Reason: cleaning up some confusion on my part....
Jan 14, 2009, 08:15 PM
Registered User
pda4you's Avatar
BEC it does have some cooling holes. Agree that may impact the readings. I did attach another tube to the static tube to keep it out of the dirty air as much as possible.

I do not have a huge powerful system on the T-craft and think the number is a tad low but in the ballpark.

I was happy it was nearly as fast at the t-28. In flight testing showed the speed difference too - I can not keep up with the stock t-28's in flight.

It is fun to "play" with anyway!

Mike
Jan 14, 2009, 08:19 PM
We shall serve the Lord
kingsflyer's Avatar
Now that is a seriously cool tool! Actual airspeed would sure make prop/power setup testing a lot more accurate. Now where did I put that credit card?

Mike McD
Latest blog entry: LEDs on my T-28
Jan 14, 2009, 08:26 PM
Registered User
pda4you's Avatar
Thanks Mike - it is fun. Estimating air speed of models is hard to do....but fun to see the results.
Jan 14, 2009, 09:03 PM
War Eagle!
Spackles94's Avatar
That's a cool little gadget, thanks for the review! It's nice to see that you won't need to use the battery, either which would make it handy for small flying wings and such, like the Hammer Models Wasp I reviewed last year.

I've heard great things about the EagleTree logger and its accessories, but this is cheaper and smaller. Neat!

Cool as well how you can just check it out at the field without the need for a laptop.
Jan 14, 2009, 10:42 PM
Registered User
Kmart's Avatar
not that it matters much, but i believe you said "park zone T-28 mentor" instead of Trojan...

Jan 15, 2009, 07:31 AM
Southern Pride
everydayflyer's Avatar
Quote:
I've heard great things about the EagleTree logger and its accessories, but this is cheaper and smaller.


Eagle Tree has a can be used Stand alone speed sensor for $43 and it has LED display , a single tube setup and seems to be extremely accurate


http://www.eagletreesystems.com/MicroPower/micro.htm

Winged Shadow Systems also has their How Fast ,plus a new improved version along with the rest of their line up..


Just mentioning alternatives that I am aware of.

Charles
Jan 16, 2009, 09:27 AM
Registered User
"Now we can actually determine with FAA certified accuracy the speed of our RC models!"

Come on. You will have to try and explain this one!

If you do a bit of research on Pitot tube design and theory you will see that this is at best an indicator and the results should be taken with a smallish block of salt. You won't see this device on any FAA certified plane anytime soon.

Gord_W
Jan 16, 2009, 10:23 AM
Registered User
pda4you's Avatar
Quote:
Originally Posted by Gord_W
"Now we can actually determine with FAA certified accuracy the speed of our RC models!"

Come on. You will have to try and explain this one!

If you do a bit of research on Pitot tube design and theory you will see that this is at best an indicator and the results should be taken with a smallish block of salt. You won't see this device on any FAA certified plane anytime soon.

Gord_W
Sure...

According to the manufacturer it is FAA certified. I didn't claim you could use this an a passenger aircraft.

Airspeed on every aircraft (that measures airspeed) uses Pitot tube. I know GPS may eventually take this over but suspect it will be a long time before aircraft are NOT equipped with pitot measurement. I don't think many pilots take their pitot airspeed indicators with a grain of salt - it is pretty key to safe flight.

You are certainly welcome to refute the claim.

At the end of the day - we are talking about RC models. Measuring their true airspeed is something we have always "guessed" at. This device takes much of that guesswork out of the equation. All forms of speed measurement have flaws - but this device is used for fun, and I think most get that.

Mike
Jan 16, 2009, 10:54 AM
BEC
BEC
Registered User
BEC's Avatar
Further on in the vendor's web site they say
Quote:
Transolve has been building electronic altimeters since 1990, our calibration is traceable to FAA grade references.
That makes more sense. Implying this particular device is "FAA certified for accuracy" - which is what the web site says today - is kind of a stretch.

GPS can never replace an airspeed indicator of this sort because GPS does NOT give you airspeed (the airplane's speed relative to the AIR it is flying in) but ground speed - speed relative to the earth. And a pilot (and/or the flight management computer in the airplane) needs airspeed even if the GPS receiver is dead. Just about everything about how an airplane works and is operated safely depends on its motion through the air (so-called "3D" models notwithstanding).

GPS is great for navigation and - in calm air - can cross check airspeed gleaned from a dynamic pressure device such as a pitot tube. We all know calm air is a rarity.

I think it is great fun to have this sort of instrumentation (certification status notwithstanding) for our airplanes. I used both a pitot/static indicator and GPS (on one of those rare calm days) from to get such data for my big Switchback review as those who have looked at it have seen. This device is another way to get max airspeeds with a simple and light device that actually measures airspeed, and so can add to the fun factor of modeling.
Last edited by BEC; Jan 16, 2009 at 11:10 AM.
Jan 16, 2009, 05:30 PM
AustinTatious
AustinTatious's Avatar
Quote:
Originally Posted by pda4you

Airspeed on every aircraft (that measures airspeed) uses Pitot tube. I know GPS may eventually take this over but suspect it will be a long time before aircraft are NOT equipped with pitot measurement.
FWIW that will never happen... there will always be a pitot tube. GPS can not measure airspeed AT ALL, it measures ground speed.

And for fun there are 5 different types of aircraft speed

1. Indicated airspeed- speed read off the airspeed indicator

2. Calibrated airspeed- Indicated airspeed corrected for pitot inaccuracies usually caused by AOA and installation errors/ differences from aircraft to aircraft.

3. True airspeed - Calibrated airspeed adjusted for altitude, humidity and temp. (more simply put, the speed at which the plane passes the air molecules)

4. Ground speed - Speed you are crossing the ground.

5. Equivalent airspeed- Sort of complex, Basically you take a current true airspeed and calculate what speed you would have to fly at sea at standard temp ( 59degrees C) to produce the same dynamic pressure on the airframe... this is more for structural analysis.
Last edited by AustinTatious; Jan 16, 2009 at 05:40 PM.
Jan 17, 2009, 10:34 PM
Really?
dll932's Avatar
Quote:
Originally Posted by Gord_W
"Now we can actually determine with FAA certified accuracy the speed of our RC models!"

Come on. You will have to try and explain this one!

If you do a bit of research on Pitot tube design and theory you will see that this is at best an indicator and the results should be taken with a smallish block of salt. You won't see this device on any FAA certified plane anytime soon.

Gord_W
Some years ago, I worked at an FAA certified instrument shop that calibrated Transolve's rocket altimeters for them-with the same equipment that we used to calibrate IFR rated altimeters, rate-of-climbs, etc. I'm sure they're having the same kind of thing done with these.
Jan 18, 2009, 07:37 AM
Registered User
pda4you's Avatar
Quote:
Originally Posted by dll932
Some years ago, I worked at an FAA certified instrument shop that calibrated Transolve's rocket altimeters for them-with the same equipment that we used to calibrate IFR rated altimeters, rate-of-climbs, etc. I'm sure they're having the same kind of thing done with these.
Too cool! I suspect it is....

Thanks....
Jan 18, 2009, 01:15 PM
Really?
dll932's Avatar
Quote:
Originally Posted by pda4you
Too cool! I suspect it is....

Thanks....
Not hard to do, just run it in parallel with a calibrated airspeed standard. That's what they do with aircraft airspeeds. He's probably using a solid-state pressure sensor in them, which are quite rugged and consistent. In fact, probably all instrument shops use a pressure measurement box called a Setra that has one in it.

http://www.setra.com/tra/index.htm


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