Michael's Sonex #145

[sonex892.]

Thats great Michael. That looks like way more fun than collecting aircraft and performance data for phase one.
Wow 4G pullup for the loop. For loops I normally aim for 130kts entry then 3G for the pullup.
Looks like a similar routine to my first recorded Sonex aerobatics a few hundred miles up the coast. Search sonex loops and rolls on youtube.
With the spins. I asked my aerobatic instructor about spins and he told me (here in Aus) that spinning is an aircraft specific endorsement and not part of the aerobatic endorsement. He told me I am legally endorsed to intentionally spin decathlons only.
Steve
Sonex 892
VH-ZSX 3300 188hrs

[gammaxy]

The pressure must be increasing at the static port while pulling G.

I just looked at some of my recorded telemetry and compared the GPS altitude to the indicated altitude. On each landing, my indicated altitude reads about 50 feet lower than it should and approaches the correct value as I slow down.

Interestingly, on a high speed pass, the opposite happens and my indicated altitude seems to be about 100 feet too high.

I suspect this is what happens when you mount a static port below the wing where the pressure measured by the port can be affected by the lift generated by the wing.

[rizzz]

Thats great Michael. That looks like way more fun than collecting aircraft and performance data for phase one.
Wow 4G pullup for the loop. For loops I normally aim for 130kts entry then 3G for the pullup.

I'll try a bit more speed and a bit less stick-back on the next loops.

Looks like a similar routine to my first recorded Sonex aerobatics a few hundred miles up the coast. Search sonex loops and rolls on youtube.
With the spins. I asked my aerobatic instructor about spins and he told me (here in Aus) that spinning is an aircraft specific endorsement and not part of the aerobatic endorsement. He told me I am legally endorsed to intentionally spin decathlons only.
Steve
Sonex 892
VH-ZSX 3300 188hrs

My instructor told me the same. this being the case, how can we ever get endorsed to spin our Sonex? No instructor can take us up and spin it with us as we're surely over the max weight for aero's with 2 people on board.
I believe my A/P had a different idea on this BTW, during the CofA inspection we went over my test flight program I had prepared which includes and aerobatic section with intentional spins being part of it. He did ask me if I knew what the recovery procedure was in a Sonex, that's all.

Anyway, I will spin my Sonex on one of the next flights though, it's not something I like to do intentionally very often but I need to know I can get out of it when it happens, so I'll go high and wear a chute.
I spun the Citabria plenty of times and I understand the recovery procedure is the same.
(I also spun a Pitts a couple of times, normal and flat, that was a slightly different procedure).

[rizzz]

The pressure must be increasing at the static port while pulling G.

I just looked at some of my recorded telemetry and compared the GPS altitude to the indicated altitude. On each landing, my indicated altitude reads about 50 feet lower than it should and approaches the correct value as I slow down.

Interestingly, on a high speed pass, the opposite happens and my indicated altitude seems to be about 100 feet too high.

I suspect this is what happens when you mount a static port below the wing where the pressure measured by the port can be affected by the lift generated by the wing.

That sounds like a very plausible explanation.
This being the case, I don't think I'll worry about it too much though, yes, in certain phases of flight my altimeter is not indicating correctly, however, those brief moments are not the ones where I'm looking at the altimeter.

[gammaxy]

I'm also not concerned about it, but it is pretty interesting. I flew today and paid attention to my altitude readout while pitching up and down and am pretty sure I get the exact same effect I noticed in your video. It is really noticeable on the vertical speed indicator. It doesn't take much push-over to cause the vertical speed to read hundreds of fpm higher than reality. If you're clever, you can probably create a climb profile where you bleed off 15 knots or so to climb fast, then subtly push forward on the stick to keep the fpm up until you've regained some speed. I'm curious if this effect has trained me to gain altitude (and lose speed) during the beginning of a steep turn--I might try to see if I can display GPS altitude on the EFIS.

I don't think it's the same thing we're seeing, but Wikipedia and several other sources describe "reversal error" as

a false static pressure reading. This false reading may be caused by abnormally large changes in an aircraft's pitch. A large change in pitch will cause a momentary showing of movement in the opposite direction. Reversal errors primarily affect altimeters and vertical speed indicators.

None of the references I have found seem to describe what mechanism actually causes it.

I've performed spins within the aerobatic weight limits with no issues. My impression was it takes some work during the mushy incipient phase to develop the spin--if you relax spin inputs any time during the first revolution or so it stops rotation pretty quickly. The transition from incipient to developed seems to happen pretty suddenly. I used the "PARE" spin recovery method and it seemed to take as much as a full additional turn to recover or at least there was a noticeable delay compared to the incipient phase.

[sonex892.]

My instructor told me the same. this being the case, how can we ever get endorsed to spin our Sonex? No instructor can take us up and spin it with us as we're surely over the max weight for aero's with 2 people on board.
I believe my A/P had a different idea on this BTW, during the CofA inspection we went over my test flight program I had prepared which includes and aerobatic section with intentional spins being part of it. He did ask me if I knew what the recovery procedure was in a Sonex, that's all.

Anyway, I will spin my Sonex on one of the next flights though, it's not something I like to do intentionally very often but I need to know I can get out of it when it happens, so I'll go high and wear a chute.
I spun the Citabria plenty of times and I understand the recovery procedure is the same.
(I also spun a Pitts a couple of times, normal and flat, that was a slightly different procedure).

I totally agree with you Michael. Even though I have not intentionally spun my sonex, I have managed to find myself in an incipient a few times during stall and slow flight testing. Recovery using the standard opposite rudder to stop the rotation then forward stick worked as expected. BTW I really enjoyed spinning the decathlon.
Steve
Sonex 892

[rizzz]

I did my first spins today.

I'm still being very cautious, I did not let the spins fully develop yet and did not do more than 3/4 turn at this stage.
It felt like she spins to the left much easier than to the right, it took a bit more effort to get the wing to drop to the right.

Here's a short video:
https://youtu.be/w4R3YD63nZE


Loops also went much better this time around, I went for 130KT entry speed and pulled a bit less G's.
The loops felt much smoother at the top.

[fastj22]

I've let my Waiex wrap up into a 2.5 turn spin. It came out quickly with just relaxing the stick and applying opposite rudder. Good fun. I've also done a 2 turn inverted spin falling out of a loop. Same gig. Just relaxed the stick, idle throttle, opposite rudder then recover. Never done it with a passenger though. Always in the aerobatic W/B when attempting.

[rizzz]

I'm happy to report Sonex #145, aka VH-MND, has completed it's 35 hour Phase I testing period as of yesterday morning.

I have written a detailed report on my adventures, findings issues etc. during this period.
For those interested in having a bit of a read, you can download the report using the link below (this is my personal dropbox so it won't be there forever):

https://www.dropbox.com/s/628avhi0vc19m ... t.pdf?dl=0

[WaiexN143NM]

Hi Michael,
Great to hear!! Congrats' going to read your report!
WaiexN143NM
Michael Radtke