AR-1 N147AR - Florida - tail strike

WaspAir said:

For my J-2 and A&S18a operations, I always advised the tower that I would need a minute in position for rotor spin-up before departure, and they would time my clearance for line up and wait with that in mind. You can't practically taxi either one with the clutch engaged, but you could perhaps do a little spinning while sitting short of the runway, release the clutch, and then engage again when in position. The problem is that it really didn't save much time because (1) you can't get it to very high rpm safely, (2) it decays quickly, (3) you don't want to sit for long periods just keeping the blades spinning with poor cooling, and (4) for the J-2, you have to re-engage the transmission each time you release the clutch and that's tricky to do without grinding gears while the rotor is in motion.

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Exactly! I used to do the same thing when I was operating my J-2 out of a controlled airport. the tower got snippy with me one time when I was in position for almost a minute for the spinup. So I always made it clear after that that I would need at least a minute in position for spinup.

Resasi said:

Nothing simple about rotor aerodynamics. If the pilot is facing into a very stiff wind the rotor RPM required in order not to incur blade flap/sail can be even higher than normal, and, also depends upon the disc angle of attack created, and the speed at which that disc angle is created.

Blade flap/sailing occurs when the rotor RPM is insufficient to cope with the amount of air being allowed to pass through the disc in any one time, ie creating too large a disc angle of attack/too rapidly at too low a rotor RPM. These are all variables and dependent upon each other.

While not disputing the need for changes in the POH, flying by numbers and instructions like ‘stick fully back at such and such a RRPM’ are not conducive to learning good rotor control, which is unfortunately, the cause of many accidents.

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Nothing is simple even about lift from a regular airfoil. But we do not sit there and tell pilots all the ins and outs and application of Kutta-Joukowski's theorem for them to operate an airplane. They do not need it at their level. They are told enough to get what they need to do to stay out of trouble.

Similarly a pilot does not need to become an expert on rotor aerodynamics to stay out of trouble. They simply need to understand enough to act appropriately to not have these incidents happen. Too much information causes paralysis by analysis in a pilot when decisions have to be made in a second.

fara said:

Nothing is simple even about lift from a regular airfoil. But we do not sit there and tell pilots all the ins and outs and application of Kutta-Joukowski's theorem for them to operate an airplane. They do not need it at their level. They are told enough to get what they need to do to stay out of trouble.

Similarly a pilot does not need to become an expert on rotor aerodynamics to stay out of trouble. They simply need to understand enough to act appropriately to not have these incidents happen. Too much information causes paralysis by analysis in a pilot when decisions have to be made in a second.

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Do you think (or know) that this was a traditional blade flap situation, or an issue that rotor RPM was too low before bringing the stick back and inadequate blade stiffness chopping the tail as is the case with MTO if one brings the stick back significantly below 160 RRPM

loftus said:

Do you think (or know) that this was a traditional blade flap situation, or an issue that rotor RPM was too low before bringing the stick back and inadequate blade stiffness chopping the tail as is the case with MTO if one brings the stick back significantly below 160 RRPM

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By calculation at 100+ RRPM he would be at 18 to 20 mph airspeed to flap the rotor and after talking to him he had accelerated to that speed because he felt rushed because a plane on final and taking immediate departure clearance. He accelerated his speed instead of milking the rotor and speed up slower. So yes I do believe ad a flap. He outran the rotor because he was rushing. He at his level or really any level needs a simplified takeoff procedure instead of understanding what exactly is rushing acceleration and whats not and where that line is.

Planes have stall angle alarms, gyros could benefit from a flap angle alarm.

Alan_Cheatham said:

Planes have stall angle alarms, gyros could benefit from a flap angle alarm.

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Except the alarm needs to take into account rotor RPM versus forward speed etc. Can be done. Someone is working on it right now. It would have to be tested well. Would people be willing to pay for it?

fara said:

Except the alarm needs to take into account rotor RPM versus forward speed etc. Can be done. Someone is working on it right now. It would have to be tested well. Would people be willing to pay for it?

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You could take rotor rpm and forward speed into account but if the pilot allows too much forward speed vs rotor rpm flapping angle will become excessive so it seems that an alarm based on flapping angle alone might be sufficient, an alarm that sounds at some angle before the rotor starts to hit the teeter stops. As you have said testing would be needed.

fara said:

They are told enough to get what they need to do to stay out of trouble.

Similarly a pilot does not need to become an expert on rotor aerodynamics to stay out of trouble. They simply need to understand enough to act appropriately to not have these incidents happen.

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Quite so, but... the basic minimum of rotor control should be just a bit more than “...then at this RRPM pull the stick fully back...”!!!

Which unfortunately is quite often the case.

Many of the factory builds do not need quite the same attention to rotor control in order to teach people to fly them given their generally greater longitudinal stability, which however does not mean that less attention to learning the fundamentals of basic rotor control should be neglected.

Being told “enough to stay out of trouble” strikes me as skimping on the basis of autogyro flight.

I see more whistles and bells than we really need.
Back in the Day, we had a tool called Rotor Management !!
Different visuals and physical inputs are all the alarms you really need.
If you exceed the envelope of safety there are ALWAYS physical manifestations that are recognisable by a skilled pilot.
If you do not have these skills then your CFI sucks or you suck as a pilot.
It may seem harsh but it sure is true.

A tactile alarm is already built in. When the stick kicks ease off.

Resasi said:

Quite so, but... the basic minimum of rotor control should be just a bit more than “...then at this RRPM pull the stick fully back...”!!!

Which unfortunately is quite often the case.

Many of the factory builds do not need quite the same attention to rotor control in order to teach people to fly them given their generally greater longitudinal stability, which however does not mean that less attention to learning the fundamentals of basic rotor control should be neglected.

Being told “enough to stay out of trouble” strikes me as skimping on the basis of autogyro flight.

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That is a CFI, student pilot training issue. A POH cannot teach you all the delicacies of rotor management

I agree with Jake. If you can’t control your rotor without bells or whistles.... maybe flying a gyro isn’t for you!!

Rotor management..... a mandatory training subject that should have a lot of time dedicated to it before ever leaving the ground!!

This VERY SUBJECT ..."Rotor Management"....was the core discussion topic of the recent Phil Harwood "Master the Gyroplane" symposium in
Arizona!
The first three days some 15 CFI's met & collaborated to throw ideas into the pot ...assess the main cause for gyro accidents (that have had our USA insurer's underwriters leaving our market in droves! with premiums getting more ridiculous!) and come up with "Best Practices to maximize the margin-for-error " solutions that need to be implemented into our gyro student training curriculum!

Looking at majority (75%) of recent insurance claims & other gyro accidents resulting in severe damage to machines ...it was clear that the MIS-handling of the moving rotor in take-off & landing/taxi phases of flight was a common factor ...OVER & OVER!

Phil shared with us ...the learning & refinements in the "best-practises" International Association of Professional Gyroplane Training IAPGT that he & other CFI's in the world have developed in the past decade!

Rotor management on takeoff with a modern pre-rotator is not some difficult complex task.

Bringing the cyclic full back at a hundred rotor rpm in an American Ranger is not even close to correct procedure.

I feel waiting for a specific rotor rpm to apply full throttle does not require skill.

In my opinion most of the rotor handling mishaps would not happen if people just followed the pilot’s operating handbook.