An extraordinarily bizarre airspeed mystery that no A&P can solve

Fix static leak, check rigging on all control surfaces after checking wash-out, and make sure the castering nose wheel isn't turning sideways in flight. Just a starting point. any of these will cause excess drag, and slower flight.
 
The OP stated, "I will send one $100 Starbucks or Amazon gift card (your choice) to whoever is the one who figures this out."

Perhaps he figured it out and is now wired up after drinking a hundred bucks worth of Starbucks caffine ... ;)
 
Did you test fly after adjusting the nose gear preload?
 
Jeff767 said:
Did you test fly after adjusting the nose gear preload?
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Yes. No change to airspeed. Only thing it did was improve ground handling when pushing back without a tow bar as the wheel doesn’t change direction as easily.
 
On my next flight, I'm going to fly with a belly mounted GoPro to check if the nose wheel is flying askew, and with a TruTach II to ensure prop RPM is correct. But after those tests are done, I'm not sure where else to go with this. I've spent dozens of hours in my head trying to figure out what could be the cause, and it vexes me so.

It's not the static leak causing this because I am in actuality flying slower, it's not just an indication error. (If you question this, please just read my previous replies in this thread confirming how I know this.) And the static leak can't possibly be causing any interference with the engine making less power because I've confirmed with both Dynon and Rotax that the 912iS ECU takes zero data from the airframe side, nor is it possible for a Dynon software update to change the ECU software in any way.

And it's not the rigging causing this because I was flying with the same half ball out, right wing slightly down at the higher airspeeds. Yes, the rigging does seem to be off, and yes, I'm going to have my A&P try to adjust it. But no, it cannot be the cause of this airspeed problem because it pre-dated it.

It's as if a parachute deploys underneath me as soon as I take off and retracts when I land and I never have a chance to see the problem. Like The Twilight Zone Nightmare at 20,000 Feet episode where he sees an alien on the wing but it disappears as soon as anyone else looks!
 
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I don't think this will apply but the point may relate.

I had a Challenger II CWS many years ago. While flying one day I noticed a slight tendency to turn to the right at cruise when my feet and hands were not on the controls. This was a new thing that was happening.

After landing I discovered a short piece of wing to aileron gap seal that was lose. It would lay down until the air got under it then it would stand up like a small spoiler on the right side wing.

FWIW ... (trying to earn some Starbucks cash!) :fcross:
 
kicktireslightfires said:
And it's not the rigging causing this because I was flying with the same half ball out, right wing slightly down at the higher airspeeds. Yes, the rigging does seem to be off, and yes, I'm going to have my A&P try to adjust it. But no, it cannot be the cause of this airspeed problem because it pre-dated it.
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FWIW, it looks to me like you were less uncoordinated previously. Nevertheless, fixing the rigging will make the plane fly faster. Maybe as fast as you need. And in fixing it, you might find an issue causing the misrigging, which could be a progressively worsening issue.
 
Daleandee said:
I don't think this will apply but the point may relate.

I had a Challenger II CWS many years ago. While flying one day I noticed a slight tendency to turn to the right at cruise when my feet and hands were not on the controls. This was a new thing that was happening.

After landing I discovered a short piece of wing to aileron gap seal that was lose. It would lay down until the air got under it then it would stand up like a small spoiler on the right side wing.

FWIW ... (trying to earn some Starbucks cash!) :fcross:
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Interesting theory. As a low-wing with bubble canopy, I have exceptional view of the tops of both wings in flight and haven't seen anything that could be sticking up in flight. I don't have any gap seal on any of my wings, either. But maybe something is going on under the wing. Unlikely, but I will probably conduct multiple flights with my GoPro just to check around the whole plane. I only bought one GoPro w/suction mount so I will point it at the nose wheel first, then probably put it under a wing at the outside edge facing inward so I can check that wing as well as the rear of the plane. Then move it to the other side. So after I do the nose wheel check, I can do two more quick flights with the GoPro at the edge of each wing facing inwards.
 
Lindberg said:
FWIW, it looks to me like you were less uncoordinated previously. Nevertheless, fixing the rigging will make the plane fly faster. Maybe as fast as you need. And in fixing it, you might find an issue causing the misrigging, which could be a progressively worsening issue.
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Yes, fixing the rigging will probably make me fly faster. But I'm not going to ignore the current issue and just focus on other ways to increase speed. That's just not how I do things -- give up on what the problem is and try to get the result through other ways. First, I fix the existing problem, then I can focus on getting even more speed than I had before.
 
Rudder trim was maxed out and ball was still 2/5 out. Less than max rudder trim causes the ball to go out of the lines even more.
 
kicktireslightfires said:
Yes, fixing the rigging will probably make me fly faster. But I'm not going to ignore the current issue and just focus on other ways to increase speed. That's just not how I do things -- give up on what the problem is and try to get the result through other ways. First, I fix the existing problem, then I can focus on getting even more speed than I had before.
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The rigging is an existing problem. And please take this in the spirit of sincerely trying to help, but you didn't notice that you were always flying uncoordinated until someone here pointed it out. Perhaps your other observations are not as impeccable as you might think.
 
I haven't read all seven pages of responses so apologize if this has already been suggested and dismissed but I had a similar problem and it was my tachometer. When it failed it read high so I was unknowingly flying around with 20% less throttle.
 
It's unsolvable as proclaimed in the thread title. Of course there is an explanation but the OP has abandoned us so we'll never know ...
 
Daleandee said:
The OP stated, "I will send one $100 Starbucks or Amazon gift card (your choice) to whoever is the one who figures this out."

Perhaps he figured it out and is now wired up after drinking a hundred bucks worth of Starbucks caffine ... ;)
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I haven't been to a Starbucks in years. That's, what...3 or 4 lattes?
 
This thread popped into my head for some reason. Wondering if the issue was truly unsolvable.
 
Lindberg said:
This thread popped into my head for some reason. Wondering if the issue was truly unsolvable.
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Dunno, but some random thoughts (coming in late to the thread and just skimming, so apologies if all this was already discussed)

From post 1 "I thought perhaps maybe I was always flying at these slower speeds and I was just seeing artificial speeds. But that can't be because my TAS was always accurate when I compared to the groundspeed and winds aloft, and my ETE times always bang on."

Did someone point out that the calculated winds aloft are calculated from the GPS ground speed and IAS? So, of course, they match.

Static leak: somewhere it was mentioned that it is "acceptable" to use the cabin as a static source for vfr. Yes, my ride is like that. But acceptable does not mean accurate. Typically cabin pressure is lower than actual static and the airspeed would read high. Reducing the leak would bring the airspeed closer to reality. So, it could be that the IAS was simply too high before and something got moved enough to reduce the leak.

Centering the ball: Trimming the rudder to center the ball if you have a "heavy" wing won't help the speed.
 
MauleSkinner said:
Slipping doesn’t add drag and/or position error in the pitot/static system?
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It can. Pitot tubes get less accurate at high angles of attack - usually not a huge problem due to a slip. Static ports - depends on the system. Some aircraft have them on both sides which somewhat mitigates the effect of the slip. Some have a static port on only one side (e.g. Cessna 120) - HUGE errors in the indicated air speed when you were hard slipping on final - slip to the left could drive the airspeed way down, to the right, it read high. Of course, with no flaps you only slipped, like, all the time.
 
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