Fatal AR1 crash 12/16/2020

Tyger

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Back to my Dad's take off.... I believe the 3 changes in pitch attitude may have been attempts at trim adjustments or feeling the stick pressure. They are definitely not negative G, and I don't see how they could have caused a significant change in the rotor rpm.
As Vance points out, there does not have to be negative Gs to cause the rotor RPM to slow – anything less than 1 G will begin to slow the rotor.
With that powerful engine at full tilt, it may not have taken much forward stick/reduced G to lose enough rotor thrust (through reduced rpm) to suddenly lose roll stability. If there was actual retreating-blade stall, my guess is it probably happened after that initial right-hand roll.
 

Brian P

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Don't think you need to lose rotor rpm to lose rotor thrust. Looks to me like he may have lost rotor thrust and torqued over.
As seen in the world air games accident.
These machines don't seem to readily bunt over but a torque over is just as deadly. And now with even more powerful engines and 4 blade props....
 

rdalcanto

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That is unlike your Dad's maneuvering, the throttle was never retarded, and pushing the stick forward while still under power will cause the rotor to unload. The rotor slowing was a few to 10"s of RPMs, coupled with the abruptness of the maneuver under power will cause blade flap.

I would never suggest you "try" the same maneuvers to test the outcome, plenty of people have already done that, hence the discussion in training to prevent such things.
There is so much rotor drag, that letting the stick forward while under power, and lowering the nose to the horizon or slightly below, will NOT unload the rotor significantly. I'm trying to say that there is no way the rotor was unloaded significantly during the 3 "PIOs".
 

Tyger

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Next time you go flying, make a fast steep climb and then push the stick forward, ever so slightly, without reducing power. If you watch your rotor tach, I think you will see a very quick reduction in rpm, as Vance just described. Then just imagine trying actually to level off from the climb without reducing power, using just your stick.
I am not an airplane pilot, but I can easily imagine an experienced airplane pilot doing this in an airplane, with the only obvious result being that light feeling in the seat of the pants. But in a gyro, that's not a good feeling at all.
 
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Vance

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In my opinion based on my testing the rotor is significantly unloaded in a steep climb because of propeller thrust and at the top of the climb because of projectile motion.

At near flight rpm an unloaded rotor slows down quickly as can be observed during the landing. The first seventy five rotor rpm decays very quickly.

The cyclic force required in the AR-1 is significantly lower than in any Magni I have flown.

As the rotor slows the cyclic becomes lighter still and the response slower.

As an experienced fixed wing pilot and an inexperienced gyroplane pilot expecting an immediate response from cyclic inputs this might encourage me to over control more.

I cannot tell from the video if the pilot induced oscillation was enough to hit the tail with the rotor.

My feeling is the convoluted flight path on the way down may have caused the rotor strike and the rotor strike may not be causal.

I simply don’t have enough information to draw any conclusions.

I introduced the projectile motion and my rotor rpm observations as it appeared there was some misunderstanding about rotor rpm in various flight maneuvers and tried to make it clear I did not feel that was the cause of the accident.
 

Tyger

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In my opinion based on my testing the rotor is significantly unloaded in a steep climb because of propeller thrust and at the top of the climb because of projectile motion.
Would you say that the greater the power of the engine / prop thrust, the greater the amount of rotor unloading in that situation?
 

Doug Riley

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In gyros that do not have full prop-torque compensation (usually via tail surfaces but other means are possible), bumping the stick forward a bit with full throttle on will produce a rolling tendency. You can see where this might get out of hand if the pilot were not expecting it. Don't try this aggressively!

Many of the past accidents attributed to power pushover actually have had a torque-over component, especially when a high-torque powerplant (e.g. an aircraft engine or a redrive engine) has been involved. This observation goes back at least to the infamous Pee Wee Judge crash of a Continental-powered Wallis at Farnborough in the early 1970's.

Ken Brock did aggressive zoom climbs in every show, but he banked hard at the top of the climb, which gave the rotor something to do by asking it to pull the gyro through the turn.

I posted some thoughts about low G in the thread about 2- vs. 3-blade rotors.
 

TyroGyro

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Just in terms of weather, I could easily imagine that many other countries have a lot more VFR/flyable hours than the UK during the course of the year.

Agreed. But maybe a few with fewer too. There are by necessity some Fermi-style estimates to be made in a job like this one.

Happily, if I am underestimating the total worldwide hours flown by using the soggy UK as a benchmark, I will be overestimating the actual worldwide accident rate...

I can live with that.
 

Vance

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Would you say that the greater the power of the engine / prop thrust, the greater the amount of rotor unloading in that situation?
More thrust or steeper climb unloads the rotor more.

It is a simple vector.

If you were going straight up with 600 pounds of thrust the gyroplane would seem 600 pounds lighter to the rotor.
 

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am not an airplane pilot, but I can easily imagine an experienced airplane pilot doing this in an airplane, with the only obvious result being that light feeling in the seat of the pants. But in a gyro, that's not a good feeling at all.
Remembered from initial fixed wing training. The pneumonics PAT and APT.

To enter the climb, it's power, attitude, trim. Start by setting climb power, as you already know. Remember to compensate for adverse yaw with the rudder. Immediately raise the nose to the climb attitude. Your instructor will teach you to recognise what this looks like in your aircraft: e.g. there might be a part of the dash that lines up with the horizon. Your airspeed will drop away to the desired airspeed for the climb: usually the best-climb speed. Once you're stable and balanced, at the correct airspeed, use the elevator trim to remove the need for pressure on the stick (or yoke).

To level off from the climb, it's attitude, power, trim. Start by lowering the nose to a level attitude. You need to start doing this before you reach the desired height, as it takes a few seconds to level off. Once you're level, the airplane will speed up. When you reach cruise speed, reduce the power to cruise power, and compensate for adverse yaw. Again, once you're stable at the correct speed, trimaway any constant pressure on the stick.

That is why carry over/muscle memory from fixed wing flying does bear thinking about.

In-built reflexes can do you an extreme disservice.


As in a lot of accidents we may have found, through experienced deduction, a chain of events that may all have contributed to the eventual fatal conclusion.

In this case it seems to be insufficient differences experience, 40 yrs of hold over from fixed wing practices, age effected reflexes, larger engine with more torque, combination of PIO, high speed climb, unloading the rotor, blade flap/sail, rotor/airframe contact, torque roll, and fatal uncontrollable descent.
 
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GyroCFI

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Next time you go flying, make a fast steep climb and then push the stick forward, ever so slightly, without reducing power. If you watch your rotor tach, I think you will see a very quick reduction in rpm, as Vance just described. Then just imagine trying actually to level off from the climb without reducing power, using just your stick.
I am not an airplane pilot, but I can easily imagine an experienced airplane pilot doing this in an airplane, with the only obvious result being that light feeling in the seat of the pants. But in a gyro, that's not a good feeling at all.
Boy, I'd be very careful with this maneuver. So many things can go wrong at the top of the climb even with a slight forward stick push... a little thermal hits you and your rotors are slapping against the teeter stops... I don't think it's ever a good thing to get to the edge of the performance envelope. I've got over 3500 hours in gyros and I wouldn't do this maneuver...
 

fara

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Boy, I'd be very careful with this maneuver. So many things can go wrong at the top of the climb even with a slight forward stick push... a little thermal hits you and your rotors are slapping against the teeter stops... I don't think it's ever a good thing to get to the edge of the performance envelope. I've got over 3500 hours in gyros and I wouldn't do this maneuver...

Power before pitch. Gyro or trike. Before levelling out reduce the power smoothly. Before climbing increase the power.
 

Tyger

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Boy, I'd be very careful with this maneuver. So many things can go wrong at the top of the climb even with a slight forward stick push... a little thermal hits you and your rotors are slapping against the teeter stops... I don't think it's ever a good thing to get to the edge of the performance envelope. I've got over 3500 hours in gyros and I wouldn't do this maneuver...
I did not say "at the top of the climb", and I just suggested an "ever so slight" change in stick position during a climb, never implying anything close to "the edge". This was only to convince Rick of the effect on rotor rpm of even a tiny bit of forward stick, as he seemed skeptical. Sometimes one must see to believe.
Please, please don't assume things I did not actually say.
 
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Resasi

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Richard, with phase 1 of EAB essentially a test pilot period, and with a higher powered than usual single coming I think this thread has produced some important points for consideration, and am personally very grateful for it to have been posted and debated.

It has brought out some important aspects for us all, newbies and experienced alike, to consider.

I hope that it may have contributed to some degree of closure.
 

skyguynca

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I did not say "at the top of the climb", and I just suggested an "ever so slight" change in stick position during a climb, never implying anything close to "the edge". This was only to convince Rick of the effect on rotor rpm of even a tiny bit of forward stick, as he seemed skeptical. Sometimes one must see to believe.
Please, please don't assume things I did not actually say.
I don't think anybody assumed anything, the warning was even with just a little bit of pressure If you manage to go through a thermal at the same time which we all know you can't see, you could hit your teeter stops, not because of what you did, but because of what the thermal did because you were out of position with forward stick pressure without reducing power.
 

Vance

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I don't think anybody assumed anything, the warning was even with just a little bit of pressure If you manage to go through a thermal at the same time which we all know you can't see, you could hit your teeter stops, not because of what you did, but because of what the thermal did because you were out of position with forward stick pressure without reducing power.
I have not flown a gyroplane that is as sensitive to a little forward stick pressure and turbulence as you describe David.

The American Ranger in particular is not that sensitive to a little forward stick pressure and turbulence.

I have explored the edges of gyroplane flight envelope slowly and progressively.
 

skyguynca

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I have not flown a gyroplane that is as sensitive to a little forward stick pressure and turbulence as you describe David.

The American Ranger in particular is not that sensitive to a little forward stick pressure and turbulence.

I have explored the edges of gyroplane flight slowly and progressively.


I did not say, that was posted by GyroCIF, It was a thread progression Vance.
This is the first comment that started this reply


Next time you go flying, make a fast steep climb and then push the stick forward, ever so slightly, without reducing power. If you watch your rotor tach, I think you will see a very quick reduction in rpm, as Vance just described. Then just imagine trying actually to level off from the climb without reducing power, using just your stick.
I am not an airplane pilot, but I can easily imagine an experienced airplane pilot doing this in an airplane, with the only obvious result being that light feeling in the seat of the pants. But in a gyro, that's not a good feeling at all.

This was the second


Boy, I'd be very careful with this maneuver. So many things can go wrong at the top of the climb even with a slight forward stick push... a little thermal hits you and your rotors are slapping against the teeter stops... I don't think it's ever a good thing to get to the edge of the performance envelope. I've got over 3500 hours in gyros and I wouldn't do this maneuver...

Here is the third and the one I replied to

I did not say "at the top of the climb", and I just suggested an "ever so slight" change in stick position during a climb, never implying anything close to "the edge". This was only to convince Rick of the effect on rotor rpm of even a tiny bit of forward stick, as he seemed skeptical. Sometimes one must see to believe.
Please, please don't assume things I did not actually say.

All I did was reply and say that, well read it yourself. Vance, I did not describe anything.
All I did was repeat what GyroCFI already posted at the start of the reply showing nothing was assumed.


I don't think anybody assumed anything, the warning was even with just a little bit of pressure If you manage to go through a thermal at the same time which we all know you can't see, you could hit your teeter stops, not because of what you did, but because of what the thermal did because you were out of position with forward stick pressure without reducing power.
 

GyroCFI

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I did not say "at the top of the climb", and I just suggested an "ever so slight" change in stick position during a climb, never implying anything close to "the edge". This was only to convince Rick of the effect on rotor rpm of even a tiny bit of forward stick, as he seemed skeptical. Sometimes one must see to believe.
Please, please don't assume things I did not actually say.
Sorry, didn't mean to take it out of context, you did however say "Fast steep climb" which is still not a good time to play with pushing the stick forward.
 

Tyger

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Sorry, didn't mean to take it out of context, you did however say "Fast steep climb" which is still not a good time to play with pushing the stick forward.
I agree, it's not something that anyone should ever normally do. That was sort of the point, just showing how sensitive it can be if you don't reduce power first.
And ya, you want have one hand on the throttle, ready to do that, that whole time.
 
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