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130kts TAS :)


Ed Cesnalis

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CT has one of the lightest planes in the fleet (what is the empty weight?), and prop pitched for 15K

density altitude, running WOT, he sure is fast. I like scrapman's challenge, though. Looking forward to the report. WF

 

As far as empty weight, mine as delivered by Flight Design had a weight of 734.4lb for a useful of 585.6lb.

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so at 13000ft doing 130KT TAS what did your indicated show?

 

98kts

 

This day produced the fastest speeds that I have seen in 10 years, I always fly WOT and generally look for fastest available speed.

 

In recent years with the same prop pitch year round I find my speeds are less than 120kts in the summer and less than 125kts in the winter.  These are at altitude and could possible be beat at low altitude where more power is available but few elect to use it.

 

In retrospect, because there was perfectly smooth wind and I was flying parallel to the crest I must have been surfing a long wavelength mountain wave and not realized it because it didn't seem to end.  Thinking back maybe I was running out of nose down trim.  

 

After 10 years of mountain flying with WOT my opinion is that I have a 123kt airplane in the winter time.  Top speed can be pretty variable when conditions permit.

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I found some pics of my Dynon in a couple situations.  Here's one showing 127kt TAS at ~5500ft, on my way down to Florida.  This was at 5350-5400rpm the whole trip, flying solo:

 

20140517_100756_zpsu9bigsxk.jpg

 

And here's one at 10,000ft, IIRC also at 5400rpm showing 122kt TAS.  There were two of us both around 195lb in the airplane:

 

20140504_111250_zpsaz7ud8yp.jpg

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I agree the CT s are about 5 to 7 knots faster in cold air versus temps above 75 degrees or so. I can also tell you all four of the Dynon equipped CTs that we have owned, read 5 to 7 knots fast on TAS compared to GPS GS tests. It would be interesting to see a turbo 914 on one of the lite fast SW s at 13K,000 ft .

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I agree the CT s are about 5 to 7 knots faster in cold air versus temps above 75 degrees or so. I can also tell you all four of the Dynon equipped CTs that we have owned, read 5 to 7 knots fast on TAS compared to GPS GS tests. It would be interesting to see a turbo 914 on one of the lite fast SW s at 13K,000 ft .

 

I'd like to see that 914 test too!

 

I think my TAS is pretty accurate, surely not off by 5-7kt.  Maybe one or two.  You can see the GPS GS in the first pic, 134kt.  I did have a tail push that day.

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I'd like to see that 914 test too!

 

I think my TAS is pretty accurate, surely not off by 5-7kt.  Maybe one or two.  You can see the GPS GS in the first pic, 134kt.  I did have a tail push that day.

 

We (gps equipped) all have perfectly accurate TAS numbers, when winds are calm.  The math is too simple at that point, GS=TAS.  When the wind blows any magnetometer error or calibration error will magnify the computed winds and therefore the resulting TAS.  So now with wind your error is either non existent or magnified a large amount or somewhere in between.  It all depends on your heading.

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It was bobbing up and down because I was hand flying and trying to snap the pic at exactly 10,000ft.   :)

 

Back in the days when every one was looking at a six-pack of steam gauges a primary point to understand early is that one gauge effects another and one gauge confirms another.  For instance vertical speed is positive and altitude increases at the same time.  If your VS was -300 it should make me think you are not level at 10,000.

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Back in the days when every one was looking at a six-pack of steam gauges a primary point to understand early is that one gauge effects another and one gauge confirms another.  For instance vertical speed is positive and altitude increases at the same time.  If your VS was -300 it should make me think you are not level at 10,000.

 

Turbulence.  I don't know about yours, but in bumpy air my CT can get kicked around quite a bit, messing with VS.  It was probably -300 for a second, then +300 the next.  I see that quite a bit.  And like I said, I was manipulating the controls to get a precise altitude in my camera shot.  It's a little hard to maintain exactly on course and altitude while fiddling with a camera phone.

 

The first pic was in dead smooth air, the second one less so.

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CTs numbers are in level flight.  Yours are in descent.  Not the same thing.

 

The point is I was *not* in a steady descent.  I was in air that was bouncing me around between positive and negative VS.  The airspeed did not change by any significant amount.  

 

My 127kt number in the first pic is in dead smooth air, 0 VS either way,  Disregard the second pic if you want.

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  • 1 month later...

It seems that there are a couple of folks that don't believe our little planes can cruise in the mid 120's so I thought I'd throw my data in the mix.  This is not about "my plane is faster than your plane" (although it is  :laughter-3293:  ) and I do not have a CT.  I fly an 804 lb Sting S3.  The DUC Swirl prop achieves 5640 rpm WOT at 4500' which is my preference here in the South Central flatlands.  I have a 1 kt delta between CAS and IAS at the range tested.  For my test, winds at altitude were forecast to be calm and Dynon was showing 'LT'.  I didn't run a 'box' but did a linear 2nm test (down and back).  I forgot my RPM (notebook is in plane) but my TAS was 118 kts both ways.  GPS read a constant 116 kts into the LT wind and 118kts back yielding an average of 117kts.  Allowing for the 1 kt CAS error and the Dynon appears to be pretty good.

 

I then cranked it up to WOT, 4500 MSL, 68F, 6200 Density Altitude, 5640rpm and 127 TAS.  

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