RV and flat spins

[n468ac]

Originally Posted by sandifer

As a teachable moment, can you precisely describe how you found yourself in what you believe to be a flat spin without attempting acro? RVs don't easily enter and sustain spins without full rudder and elevator deflection held and maintained.

I'm at work this morning, but here it is...

During Phase 1 testing, we were testing power on stalls with 200lbs in the pilot and 200lbs passenger seat, full fuel and 100lbs of baggage. I was setting up for a test with a 30 deg bank left turn, I was somewhere between 90% and 100% throttle, in a climbing turn at 30 degs at about 65knots, over 8000?. This was going to be the first left turn stall, I had just completed three right turn stalls. All the right turn stalls where uneventful.
My head was down writing down the test data, alt, time, temp, pressure alt, speed, bank angle, fuel level readings, etc. When I was whipped around like I hit something ... I clearly remember seeing the rotation and thinking "this isn't right" ... then the nose came up and I could no longer see the horizon. At this point I really knew it wasn?t right ? I don?t recall how many turns happened before I started to do something ? I tried the normal inputs ? Nothing happened ? speed of the rotation was increasing ? I tried other inputs without anything responding. I only thing that came to mind was reading somewhere about pumping the stick to break a spin. THAT WORKED!
The nose fell straight down and the spin stopped ? I pulled power and pulled back on the stick. Looked at the EFIS and saw I was at 3000 feet.
1. Looking back I tell everyone ? when you don?t expect something to happen and it does, it takes a few seconds for your mind to register, then a few more seconds for you to do something. I?m sure I froze and held the inputs that made the matter much worst and keeping power on sure didn?t help.
2. I was wearing a parachute during the test ? but during this whole event never ever thought about bailing out, to this day I think I should have had a minimum alt written and posted on the panel. IF IT GOES BAD GET OUT AT xxxx.
3. Good thing we had all the ballast tied down good, if it broke free who knows what would have happened.

This was one of those life lessons that really gave me a different prospective on accidents.

[sandifer]

Originally Posted by n468ac

I'm at work this morning, but here it is...

During Phase 1 testing, we were testing power on stalls with 200lbs in the pilot and 200lbs passenger seat, full fuel and 100lbs of baggage. I was setting up for a test with a 30 deg bank left turn, I was somewhere between 90% and 100% throttle, in a climbing turn at 30 degs at about 65knots, over 8000?. This was going to be the first left turn stall, I had just completed three right turn stalls. All the right turn stalls where uneventful.
My head was down writing down the test data, alt, time, temp, pressure alt, speed, bank angle, fuel level readings, etc. When I was whipped around like I hit something ... I clearly remember seeing the rotation and thinking "this isn't right" ... then the nose came up and I could no longer see the horizon. At this point I really knew it wasn?t right ? I don?t recall how many turns happened before I started to do something ? I tried the normal inputs ? Nothing happened ? speed of the rotation was increasing ? I tried other inputs without anything responding. I only thing that came to mind was reading somewhere about pumping the stick to break a spin. THAT WORKED!
The nose fell straight down and the spin stopped ? I pulled power and pulled back on the stick. Looked at the EFIS and saw I was at 3000 feet.
1. Looking back I tell everyone ? when you don?t expect something to happen and it does, it takes a few seconds for your mind to register, then a few more seconds for you to do something. I?m sure I froze and held the inputs that made the matter much worst and keeping power on sure didn?t help.
2. I was wearing a parachute during the test ? but during this whole event never ever thought about bailing out, to this day I think I should have had a minimum alt written and posted on the panel. IF IT GOES BAD GET OUT AT xxxx.
3. Good thing we had all the ballast tied down good, if it broke free who knows what would have happened.

This was one of those life lessons that really gave me a different prospective on accidents.

Reading this, I'm still unclear exactly how the inadvertent spin was entered. I assume it spun left? Were you inadvertently holding a lot of rudder or elevator while you had your head down? If you were in a climbing turn, not paying attention, with the controls fairly neutral, you should have just flown a parabolic arc as you ran out of airspeed on the way up. Not trying flame you or anything, just trying to gain some clarity for the purposes of education and safety.

What was your previous spin experience and training? Did the spin truly remain in a flat, level attitude until it recovered? Can you describe in detail the inputs you were applying that did not work, and how long you held them before bailing and trying something else? I've read a lot about spins of all types, and recovery techniques, but the stick pumping thing is a new one for me. If it works it works, but I suspect you may have been doing something else that contributed to the recovery despite the stick pumping. Just curious what you can remember with clarity, and if your previous spin experience or training was sufficient to give you some perspective about the mechanics of how you got there, the true nature of the spin itself, and what led to the recovery.

So do you understand exactly what happened and how you recovered, or in the future will you simply make an effort to avoid at all costs stalling the airplane in a similar configuration? Again, not trying to blame or flame, but yours is an unusual story that could be beneficial to others.

[n468ac]

Originally Posted by sandifer

Reading this, I'm still unclear exactly how the inadvertent spin was entered. I assume it spun left? Were you inadvertently holding a lot of rudder or elevator while you had your head down? If you were in a climbing turn, not paying attention, with the controls fairly neutral, you should have just flown a parabolic arc as you ran out of airspeed on the way up. Not trying flame you or anything, just trying to gain some clarity for the purposes of education and safety.

What was your previous spin experience and training? Did the spin truly remain in a flat, level attitude until it recovered? Can you describe in detail the inputs you were applying that did not work, and how long you held them before bailing and trying something else? I've read a lot about spins of all types, and recovery techniques, but the stick pumping thing is a new one for me. If it works it works, but I suspect you may have been doing something else that contributed to the recovery despite the stick pumping. Just curious what you can remember with clarity, and if your previous spin experience or training was sufficient to give you some perspective about the mechanics of how you got there, the true nature of the spin itself, and what led to the recovery.

So do you understand exactly what happened and how you recovered, or in the future will you simply make an effort to avoid at all costs stalling the airplane in a similar configuration? Again, not trying to blame or flame, but yours is an unusual story that could be beneficial to others.

I don't take your questions as blame or flame ... I don't understand how it entered the left spin and to this day not sure completely what I did during the spin. I do know that after pumping the stick the nose fell like all the spins I've been in before. I have since spin the RV6A 3 or 4 times at aerobatic weight of 1375 and never saw the nose rise, like it did that time. My guess and only a guess is the weigh and balance was such that it caused the flatness. I am 100% sure that until the end, the nose was above the horizon. My previous spin experience was in 152, 172, and 182.

[jrs14855]

I think the factors were:
Less than optimum vertical tail, ie, larger than original RV6 but smaller than RV6 "big tail"
Relatively aft CG
Entry at high power setting
Failure to immediately reduce power to idle.
Almost all of the popular high performance aerobatic airplanes will recover from flat spin with full power, however on aircraft such as the RV6 this is an unknown.
Side by side aircraft, especially those with a relatively large canopy/cabin structure, have a history of less than stellar spin recovery. In contrast, tandem aircraft with huge bubble canopies such as the Sukhoi SU29 and two place Extras, don't seem to be affected by the large canopy.

[BobTurner]

Originally Posted by n468ac

My previous spin experience was in ..... and 182.

What? Or is that a typo?

[SMO]

During the testing of my Rocket I did a series of tests to see where the stall speed was with a 60* bank. I would put in a right bank and then pull to keep the nose somewhere near level, effectively doing a 2g turn. Then I would slowly pulled the power back till I got the stall. The turn would tighten significantly as the speed decayed. The stall occurred without much (any?) warning. On the first couple of them the airplane immediately rolled (snapped?) opposite the bank input effectively bringing me back to level. However the third one went the other way putting me inverted. A slight pull on the stick and full aileron in the direction of the roll brought me back around. I suspect on the first two I was slightly uncoordinated to the left, and the third was slightly uncoordinated to the right. As I enjoy a few aerobatics regularly the sight picture was not unusual, and the recovery inputs were automatic.

I am reiterating this experience as I see a similarity to what happened to Christopher. While in this case the bank was only ~30*, power was significant. I wonder if the airplane flipped inverted, followed with incorrect inputs (forward stick?) which maintained the stalled condition, and not being perfectly coordinated the inverted spin would begin. Not saying it was exactly like this, but can see it happening to me if aerobatics were not part of my regular flying regimen.

[sandifer]

Originally Posted by SMO

I am reiterating this experience as I see a similarity to what happened to Christopher. While in this case the bank was only ~30*, power was significant. I wonder if the airplane flipped inverted, followed with incorrect inputs (forward stick?) which maintained the stalled condition, and not being perfectly coordinated the inverted spin would begin. Not saying it was exactly like this, but can see it happening to me if aerobatics were not part of my regular flying regimen.

Christopher was describing an upright spin rather than inverted. I hope folks who may not have had spin training don't read this thread thinking that fear of spins is necessary when doing simple stalls, power on/off, banked, accelerated, etc. Generally speaking, you will not spin unless you have the rudder AND elevator near full deflection. Anything less will typically be a spiral, which is can be flown right out of.

Even if, when doing any kind of stall, you get a sharp wing drop, roll, etc., this does necessarily mean you are entering a spin. It just means there's some lift differential at the moment the stall occurs which translates to roll. Try to stay coordinated, but many pilots are taught (and continue to think) that the slightest bit of uncoordination during a stall will result in a spin. Not true. It takes a lot of yaw force present - yaw force that neutral rudder will typically prevent. You're more likely to spin during stall practice if you really hamfist or use all three controls improperly AFTER the stall break occurs. If you just pull power and neutralize all three controls as soon as the stall breaks, the worst you will be left with is the need to roll to level flight with ailerons from an unusual attitude. Unless you've had spin training, fighting the stall with extreme control inputs is more likely to get you into trouble.

I went up in the Pitts once trying to create a situation where I could produce a spin with NO rudder deflection. I was successful, but it was only possible in one specific configuration, and it was slow to develop. During a power on stall entry, I kept the rudder neutral, and held full aft stick and applied full right aileron as the stall broke. The nose dropped, the airplane wallowed around for a few seconds, and then slowly adopted a stabilized, flattish spin to the left. Power was still on. I confirmed this was truly a spin and not a spiral by pushing the stick forward to neutral. The spin rotation continued. Recovery was normal with anti-spin inputs. I could not produce a power off spin with no rudder deflection no matter what I did. I would expect it would be similarly challenging to produce a spin in an RV with no rudder. Fun things to experiment with.

All that being said, good spin training has a whole lot of value.

[jrs14855]

There is considerable evidence that many of the pre WWII airplanes would spin with aileron only. By the time production resumed after WWII this had been mostly corrected.
The Sukhoi has a relatively benign one G stall. However as the G load is increased to induce a high speed stall, the event becomes more and more violent. I saw one relatively experienced pilot stall the airplane out of a steep bank turn, he was pulling a lot of G, and the airplane snapped about a turn and a quarter, back to relatively level flight. He had no idea what had happened. This occurred with very slight rudder input.
One of the things I demonstrated in the Sukhoi was to stall the airplane in a climb with a moderate power setting, aggressively apply full power, and raise the nose 5 degrees. The airplane would power out of the stall. A lot of aileron and rudder could be used without any hint of a secondary stall or spin.
Yurgis Kairys, in the SU26, would do half of an octagon loop on takeoff, started right from liftoff, the entire maneuver being done just above a stall.

[Camillo]

Thanks for all your answers. Sandifer, what you wrote is really useful and is what I was searching for.
I am not far from completion of my -4 and was wondering if she could enter in an unintentional flat spin.
I am at the middle of my acro training (5 hours done) and my instructor told me he will only show to me one flat spin. He also added that if I enter in a flat spin alone, I will be dead.
Now I understand it may be different, but at an adequate height.

[maniago]

Originally Posted by Camillo

He also added that if I enter in a flat spin alone, I will be dead.

I'm only watching from the sidelines, but this statement, which you've noted twice now, from an instructor teaching upset training bothers me a bit. We all know flat spin recovery is doable, albeit a very advanced maneuver. But to put the fear of dying into you while youre trying to overcome that with training, seems counterproductive, to say the least. If the guy said "hey I'm not comfortable teaching flat spins, its too risky" yeah I get that, but to put it this way, I dunno, I'd probably be inclined to find another instructor.