what happens if I use the prerotator in....

[flyover1974]

...flight ?
Hi, my name is Hermann and most of the time i'm in the german gyro forum. I get no answer there for this question so maybe someone here can help me.

I have a question about this situation:
You loose rotor rpm during flight under the minimum for autorotation (for any reason whatsoever) but without any damage. You have enough space under your seat and enough time to react and do anything helpful.
What happens if I use the prerotator in flight to get back the min. rpm for autorotation ?
I think that is possible and always better than waiting for impact ?

ceers
Hermann

[CLS447]

It the blades were slowed down that much.......they would probably start flapping.

At this point get your head between your knees & try to kiss your ass goodbye !

I don't think that you could recover flight RPMs with the prerotator !

First of all.....how could you lose the rotor speed in the first place ?

Name a couple of the ways..........

[flyover1974]

Hi Chris,
maybe with negative G on the rotor...a very strong downward wind for some seconds or an inexperienced pilot in climb situation at full power push the stick too fast foward but this probably ends in a side flip or foward flip..
You are right, probably that situation ends in blade flapping but my question is only in theorie, meaning you are lucky and no flapping or bade crash.

ceers
Hermann

[jcarleto]

Hermann,

A simple answer is no, for two reasons:

1. Rotors like to spin. It is really difficult in all but the most absurd conditions to get them to spin down to a point where they would not become recoverable by normal means or had past the point of no return into unrecoverability. As it has been said, because of the potential for flap and other issues, the likelihood of fixing that with a pre-rotator is not good. You would also run the ever-so-slight risk of jamming the pre-rotator into the ring gear and causing a problem you didn't have before you tried to engage the thing in flight.

2. If you had altitude, as in your scenario, it is a fairly simple matter to load the blades back up by normal attitude control with your cyclic. Also in your example, you don't "lose auto-rotation" in a gyroplane. Even if the blades are running so slow they are flapping and tearing your machine to wreckage, they are doing so in auto-rotation.

This should all become clear once you have had some real-time experience with an instructor in slow flight, vertical descents and other general operations. I should also mention that while they may exist somewhere in the dusty collections of accident records, I have not heard of an incident where the root cause was insufficient rotor speed at altitude. I know personally of at least a couple where the root cause was pre-rotator jammed in the ring gear during flight.

That said, it is not uncommon for pilots who are either distracted or inexperienced to get behind the power curve close to the ground and not have enough altitude to correct the problem. They still are in auto-rotation and still have significant lift...just not enough to prevent an unhappy meeting with the earth, a tree or other unfriendly object. Even in these cases, a pre-rotator is likely to cause more trouble than it fixes. In very general terms, what is usually needed is more thrust out of the engine to help clear the problem....or better skills, more practice and mind on one's business.

I should also mention that some use a pre-rotator during the take-off roll for assist in short-field takeoffs and do not disengage until breaking ground. That might be useful...I don't do it...but I see no real harm in it.

[Gyro28866]

I would think that if you could get the pre-rotor to engage. As you applied sufficient power to re-spin the blades up. you have also applied a high power/thrust to the airframe; which would lead to a PPO.
If you have flapped the blades by now. you have destroyed the control system and head and frame.
you might even have become a Big yard Dart, by this time!

[BEN S]

You might possibly impart a spin as the only way to counter the torque is with air over the rudder. I once left on my rotor brake and didn't notice untill after my flight! Even that didn't slow down my rotors to the point of not flying. If you start to slow the rotors in flight you will desend not fall out of the sky.

[Gyro28866]

"I think that is possible and always better than waiting for impact ?"

I think any pilot with any skill level is going to try something to make a recovery.
Proper or not-proper technique!
Something is better that nothing.
But
as with any aircraft.
remember a cardinal rule in a incident/crash/Oh Sh$t moment/etc.:
"""ALWAYS FLY THE AIRCRAFT."""
until it's over!

[flyover1974]

Thank you guys for the explanation.
I fly a MT03 from Auto-Gyro and on this gyro is not possible anyway to engage the prerotator in flight.

Hermann

[GyroDoug]

You guys are all full of it. I know it must be possible to pre-rotate rotors back up to flying speed while in the air, because I watched James Bond push a Helicopter out of the back of a cargo plane and then spin up the rotors and start flying. He pulled the Helicopter out of a dive just before it hit the grouond. It was very impressive and I saw it with my own eyes so it must be true and possible.

[Mike484]

Originally Posted by GyroDoug

You guys are all full of it. I know it must be possible to pre-rotate rotors back up to flying speed while in the air, because I watched James Bond push a Helicopter out of the back of a cargo plane and then spin up the rotors and start flying. He pulled the Helicopter out of a dive just before it hit the grouond. It was very impressive and I saw it with my own eyes so it must be true and possible.

Yea, and I saw Bart Simpson hover a gyro!

[Gyro_Kai]

I think that scene was in Charlies Angels, but true of course.

Kai.

[JonVos]

What about the unforgettable moment in the recent A-Team movie where Murdock pulls vertical in the Huey, shuts the engine off and stops the rotor blades from turning. This was done to confuse a heat seeking missile. The engine had a little bit of trouble re-starting (the sound effect was from a centrifugal starter on an old radial engine) but eventually (right after Face almost fell out but was rescued by BA Barracus) it spooled back up, the rotors started turning again and they flew away to safety. Totally realistic. Oh, and this was right after they did a barrel roll. Also very cool. Maybe I should go try this in the gyro tomorrow. I'll take my GoPro so I've got cool footage of the crash.

[shootthrees]

I know it there has been discussion about using a Ballistic Recovery System (BRS) with a parachute on this forum in the past.
And I understand that unlike airplanes, the problem is in deploying it without hitting the rotors. But, if the blades have stopped or can be stopped from spinning with a rotor brake at a high enough above ground level altitude, then the BRS, if installed, could be deployed.

It seems that it is rare that blades stop spinning and fall out of the sky at BRS recoverable altitudes. The following questions come to mind for the possible use a BRS on gyros:

1. At what above ground level altitude have most bunt over or rollover accidents occurred? My guess is that they normally happen either on climb out or during an approach.

2. Have Rotor Heads or Mast been known to catastrophically fail in flight with or without a large bird strike or collision with another craft? (I almost hit a hawk in a FW ultralight.)

My point is that with enough altitude and a completely disabled rotor or during a bunt over or rollover, then a BRS could save your butt in rare situations!

So is the BRS worth the extra weight and cost or is this an absurd idea for gyros?

[jcarleto]

Tom,

To your #1:
A lot of bunts occurred in level flight due to over-correction of turbulence. Either way, inertia is going to keep you spinning (hence the term "bunt"). Probably not the best situation to release a bunch of cloth and strings.

To your #2:
Oddly enough, rotors generally "win" against most birds. Here's the real problem: You have a LOT of inertia in spinning rotors. To stop them, even with serious brakes, the inertia has to go somewhere. If you use a braking sysem, it will be a "breaking" system, because something is going to break if you try to stop all that momentum quickly enough to do any good. And no, mast failure is reasonably rare unless there is a ground/tree/water strike. In a collision with another aircraft, all bets are off no matter what you are flying.

There is one gyro manufacturer who sells a BRS for their gyroplane that is designed to blast downward and flip you upside-down. I will only say that I have no plans to install one on my gyroplane.

[DieselPower]

I was thinking about this the other day, and I think the only safe way would be to have a charge in the hub bar that would blow the rotors off and then deploy the BRS, and that would not be impossible...