[pierre smith]

...or do you just have what it gives you? Reason for the question, is that yesterday I went to 8000' DA and did a 4-way GPS run at 75%. The 496 average was 200.375 MPH but the Dynon 100 said 205 TAS the whole time.

The barometer has been calibrated to match my standby steam altimeter and they both match.

They're not open yet (PST), so I figured I'd ask.

Thanks,

 

[rvator51]

It doesnt have a direct adjustment of TAS. However the following can affect the TAS.

OAT placement. Make sure it isnt getting hot air from the cowling and I have also heard that it shouldnt be put directly in the airflow as it will indicate a few degrees higher from the ram air on it. I have mine under the vertical stab.

IAS can be off because of static air location or other problems.

There is an adjustment on the Dynons you can do for zero airspeed

 

[rvmills]

Pierre,

Concur with what Tom sez.

FWIW Using the 4-way GPS run spreadsheet from Kevin Horton's website, I also have seen a slightly higher Dynon TAS than the results from the GPS runs. It's been consistently from 2.5 to 5 knots difference (and always in the same direction...TAS > GPS speed). As I make more speed mods during the winter and do some more testing, I'll keep an eye on the delta and let you know how it goes. I'm thinking if I can keep it under 5 knots...and especially if it shows closer to the that 2.5 knot range, I'll be pretty happy with it.

I'm basing that on some of the discussions on this in the forum. I've seen it discussed that a flush static port will make the airspeed read high (I believe that's the direction of error), and my buddy Rocketboy has done some playing with adding washers to get the airspeed adjusted on his F1. I think he's within 2 knots on testing, and is happy with that. I think others have experimented with little dams in front of the static port, or have gone from flush back to the basic rivet (which is what I have).

Also in the FWIW category, during the last two races, my "gut evaluation" of my TAS was about 2-3 knots faster than my actual final timed airspeed. That of course is pure "SWAG", as the final time includes wind and climb/descent effects. But it seemed pretty consistent to me.

On the OAT side of the equation, mine is back under the right H-stab, for a data point.

Just went digging through the latest D-100 Install manual (found here: http://www.dynonavionics.com/downloads/Install_Guides/EFIS-D100 Installation Guide.pdf)

There is a discussion of the OAT probe install and OAT adjustments that can be made (if you think the OAT reading may be off) on page 7-9.

I couldn't find the section on the zero airspeed calibration, but I do remember reading that if you do it, make sure there is absolutely no ambient wind (I did in a hangar a long while back).

Good luck as you play with this, and if you find a fine tuning method that gets you closer, I'd love to read about it!!

Sooooo, as you play with airspeed (and that's not too shabby at 75% by the way), are you prepping to be the inagural RV-10 SARL racer?

Cheers...and Merry Christmas!
Bob

 

[pierre smith]

Could be...

Pierre,

.......Sooooo, as you play with airspeed (and that's not too shabby at 75% by the way), are you prepping to be the inagural RV-10 SARL racer?

Cheers...and Merry Christmas!


Bob

....the first -10 racer, but no, I was urged to go even higher by Bill W. on here, since he sang the wing's praises, but I didn't go to 10,000 as he suggested. What amazed me, was the fact that at a DA 0f 8050', it still pulled over 23" and I wasn't expecting that much ram air, so I reduced power to 23" for the runs and 2400 RPM, my usual cruise settings, running at peak EGT's, around 14.7 GPH,

Best,