Article Transolve AirSPeed Gage Max Speed Recorder Review

[BEC]

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.

[pda4you]

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

[kingsflyer]

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

[pda4you]

Thanks Mike - it is fun. Estimating air speed of models is hard to do....but fun to see the results.

[Spackles94]

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.

[Kmart]

not that it matters much, but i believe you said "park zone T-28 mentor" instead of Trojan...

[everydayflyer]

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

[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

[pda4you]

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

[BEC]

Further on in the vendor's web site they say

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.

[AustinTatious]

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.

[dll932]

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.

[pda4you]

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....

[dll932]

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