bobmarkert

bobmarkert

Well Known Member
Phase 1 testing is going extremely well. Today I was expanding the G envelope at max aerobatic weight. Using incremental steps I was working my way to the limit of 6 Gs in ? G steps. AT 5 ? Gs I experienced to solid bumps. It felt like it was more aerodynamic than mechanical,... as if I went through my own wake?. but I was in a straight pull so it wasn?t wake (at least not mine). Any thoughts (accelerated stall?)? Will be looking over the aircraft thoroughly but the post flight showed nothing abnormal

 
I have not had my 4 past 5Gs in straight and level or turns, but when doing full aileron deflection rolls you will get bumps as the ailerons stall and recover. It feels very weird the first time you do it, and bumps every 2 seconds or so. It is possible your elevator is doing the same thing. I have not experienced any "G" related bumps.
 
You may have stalled the aircraft. At what airspeed were you performing the test? You need to look at the speed when the bumps occurred. At a high G loading if you were in a level turn it will be bleeding airspeed rapidly.
G
 
aileron bump

Bill, I am familiar with the aileron bump and mine is typical. When the ailerons go Bump (in the night) I can feel it feeding back through the stick. This felt like it originated in the wings not the tail and there was no feedback in the stick. I will download the Garmin data stream and look at the speeds
 
Bob, what was your AOA saying at the time? I've done 5.5 (straight pull) and didn't have a bump, not that that means anything.
 
will check data

Billiam,
I was in a straight pull from a dive. I was also at 10,000' (4,500 agl) so that didn't help. Testing in Denver can be challenging due to altitude, as you know.
 
bobmarkert said:
Billiam,
I was in a straight pull from a dive. I was also at 10,000' (4,500 agl) so that didn't help. Testing in Denver can be challenging due to altitude, as you know.
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What was your indicated airspeed at the time of the bump? If it was much less than 123 KIAS (I assume you were under gross), then it was most definitely accelerated stall. In my -8, the onset of accelerated stall feels just as you've described...a noticeable "bump".

In one -7 that I've flown, accelerated stall felt like driving over "washboard".

Skylor
RV-8
 
Accelerated stall

After looking at the data stream, I'm confident it was an accelerated stall. Next flight I'll increase onset rate (wary of G overshoot) with a slicing turn (no rolling moment). Then comes the interesting test....... negative 3......
 
I had an rv-6 that did the same thing coming out of loop at bottom at 10,000 ft, it wouuld stall causing bump the G pull was less than 5,5
 
Loops

RV Jerry said:
I had an rv-6 that did the same thing coming out of loop at bottom at 10,000 ft, it wouuld stall causing bump the G pull was less than 5,5
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Coming out of the bottom of a loop, I would be much more inclined to believe you experienced your own wake turbulence, which also feels like a sudden vertical "bump". This is common on loops, Cuban 8's and steep 360 degree turns.

Skylor
 
RV Jerry said:
I had an rv-6 that did the same thing coming out of loop at bottom at 10,000 ft, it wouuld stall causing bump the G pull was less than 5,5
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It would have to be a very unusual loop to encounter a accelerated stall at the bottom. I suspect you did a very nice loop and flew through your own jet wash.
G
 
No loop

Just for clarification this did not happen during a loop. It happened during a straight pull from a straight ahead dive. I wanted to be upright with an upward vector when Max G occurred. I'm pretty confident it was an accelerated stall and not hitting my own wake turbulence. Thanks for all the info
 
If you post your weight, TAS and G and the clean 1g stall speed at max gross it would be pretty easy to work out how close you were to the stall. If you were below Va you were likely hitting the wing stall. Above Va you should, by definition, be able to go to limit load without stalling assuming that load is 6g at aerobatic weight,
 
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