Accident - Rotorsport MTOSport G-PALT, Beccles airfield, Suffolk, UK

All_In

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After a 5-year cancer break. I start training again next week on my driver's license.
Not waiting for the final verdict of the FAA for 3rd class medical.
I will tell you my stupid human tricks.
If it becomes challenging I will share that too.
If I cut off my tail you will hear about it, if not from me at first, then when I get out of the hospital, or if not in the news...
 
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Resasi

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Just a thought to bear in mind with regard to number on gauges, your estimates on what speed, and where you might lift off?

Wings/rotors are lift devices that perform in accordance with WAT limits.

Weight, Altitude and Temperature, all of which effect air density, and that, alters the speed you lift off, and the length of your TO run.
 

Tyger

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It was his first solo flight he totally forgot to put the stick back AT ALL.

Held it all the way forward and only realized he was supposed to pull back on the stick at or near take-off speed.
So he did, not knowing what else to do.
One wack the tail was gone and it rolled on its side. In the case of forgetting to pull the stick back at all, it is better never than late!

Said he panicked that he was by himself and not thinking of the procedure only he's not ready.

No one thought to trained him if you forget to pull back the stick. Pull power and stop.
My instructor was watching me closely from the ground on my first solo, radio in hand. He would have said something right away if he'd seen my rotor not tilted back.
 

Doug Riley

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All In: re your Post 119. I had no prerotator for years. I flew at little rural airports, where taxiing around to spin up blades usually wasn't a problem. Simple, light, and cheap were the watchwords.

When I bought a gyro with a Wunderlich, I didn't know you could keep the prespin engaged during your takeoff run. I therefore would release it before starting my roll -- just as many POH's still prescribe. You lose a few RRPM's this way, and you must back off throttle to just the correct engine RPM to accelerate both airframe and rotor at the rates they will tolerate. That's the complexity. But that's what I did, knowing no better.

Then I met Ed Alderfer at a flyin. He watched me fly using my "release-before-rollin'" method. He suggested that I keep the prerotator engaged well into my roll. I said "Duh, didn't know ya could do THAT."

Then I tried it and liked it. Not only is it a bit simpler that release-n-roll, but the combination of continued engine drive PLUS wind drive spins the blades up faster than wind alone, with no loss of RRPM in the transition. The governing effect on engine RRPM (because of the extra load) helps you avoid leaping ahead too fast. You don't have to power down at brakes-off.

I've usually used this technique ever since. It works on Wunderlich, Dominator and Butterfly-MetroLaunch prerotators. I can't comment on others.

When the prerotator isn't functional, I still hand spin and coax 'em up to speed the old Bensen way. I've done this even with 28-foot Dragon Wings, though it's very tedious 'til RRPM gets over the "hump."
 

Tyger

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In re that video: it does look like it's torque yawing right the instant the main wheels lift off. He might well have still had the prerotator engaged.
 

Doug Riley

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It looks to me as if the blades have already started hitting the ground (kicking up dust) before the mains are off. This happens at 0.40.

Of course, such ground strikes would roll the gyro left. With the nosewheel off and the tailwheel down, a Bensen-style gyro becomes a sorta-taildragger, susceptible to ground looping. That, too, could account for the right yaw.

Obviously, this mess could have been saved by powering way down and pushing the stick forward. "Press on regardless" is not always good advice.
 

Tyger

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Hmm, if you pause it, I think you will see that the blades are not hitting the ground at the time that the mains come off, but that the yaw right happens just at the moment they begin to lift off.
 

Doug Riley

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The image is a bit blurry, and more so because, when stopping it, you sometimes get two frames superimposed. I THINK I see dirt flying as early as 0.38, though.

The Bendix SHOULD drop out even with the clutch lever/handle still engaged. That's what it's for. The Bendix on Wunderlich prerotators has the additional fail-safe of an override ratchet. I imagine others do, too.

COULD the Bendix stay engaged despite all that, making the gyro a helicopter without a tail rotor the moment it lifts off? Yes. Mine hung up once on takeoff, for just a moment. The gyro's nose slewed 'round to the right maybe 70 degrees before returning to coordinated flight.

Once the blades start plowing dirt, even lightly, things go from bad to catastrophic. The loss of RRPM is going to make any retreating blade stall much worse, digging them in deeper on the next rev. The Bendix might REengage, given the now-lower RRPM (if the pilot still hasn't let go).
 

All_In

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I believe Willy, Et El, are correct about the prerotator being engaged.
Is there any other control failer but the rudder that would yaw the nose by about 70 degrees?

To see the dust at first is caused by the propwash and not the blades until they hit.
Click the 'Gear icon' (setting) button on the YouTube video.
Then click 'PlayBack Speed' and set it to 0.25 = 1/4 speed. It shows it clearly at that speed.
 
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Tyger

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I would NOT assume that a Bendix will always drop out, depending upon how your particular system works, of course.
If it's driven by the prop/engine (e.g. Magni) and remains fully engaged, the Bendix may NEVER end up spinning slower than your rotor... until you release it.
 

anthom

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Not to drift this thread. I observe the following:

The nose wheel comes up at 37, the gyro seems to be riding on the tail. Does not look like any attempt was made to lower the nose.
38 Second.png

Prop seems to be turning clockwise (viewed from rear).

Right yaw begins at 39/40 when nose wheel lifts off. Pitch attitude still seems high. Left roll begins at 41. Left wheel digs in creating a pivot point for a dynamic roll over. Nose pitches up even more.
40 second.png

The rotor then hits the ground on the left at 41 with a steep pitch up attitude, and it's all over.
41 Rotor strike.png

IMHO, The pilot did not attempt to ease the nose down to accelerate the gyro after the nose wheel came up.

It may have been possible to have closed the throttle when the yaw started. That might have killed the torque and the subsequent roll. May have also disengaged the bendix.

So the accident gyro in this thread had the cyclic forward, and I believe the video gyro had the stick too far back after lift off. Both recipes for disaster during take off.

Just my thoughts...
 
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