Rotor Management

[ElJay]

Hi. Been doing ALOT of reading here and am grateful for being able to access this fantastic medium.
Anyway, Could/Would someone write up a sort of "outline" as to what happens, what to expect as you go thru takeoff start to finish.

How do you know "what" rotor rpm you have at any given time and what are the critical numbers, for takeoff, normal flight etc. I assume that the faster forward you go, the faster the rotors turn, which would increase or at least maintain altitude.

I hope these questions are not too vague, but am not versed enough to know how to speak it yet...

Thanks
LJ

[ventana7]

LJ,

In brief as you finish pre-rotating and start rolling down the runway you need to keep the rotor rpm increasing as your airspeed increases. You will get airborne when your rotors spin fast enough to create more lift than your total weight- usually around 330+.

The method is not to add full throtle until a certian rotor rpm. If you get too much airspeed before the rotor rpm is up you can get flapping which feels like a sledgehammer hitting your machine and massive stick shake. If you get too much rotor rpm before enough airspeed you can pop off the ground before you have enough speed to fly and you fall back to the runway. However the windows on both airspeed and rotor rpm are wide so it is easy to keep both in range and avoid the two problems I described.

Once airborne you really do not need to monitor your rotor rpm- it will be whatever it needs to be to support your machines weight. It will increase in turns as you pull more G and the machine weighs more.
In advanced flying like the musterers do yanking and banking at 20 feet off the ground then rotor speed management becomes more important but I'll let birdy or chopper describe that as its way over my head.

Rob

[bones]

I agree with what you said Rob, there is nothing you can do to make the rotors do any thing but to spin fast enough to support the weight, and as you said we do some things that NORMAL people consider crazy, I too would like Birdy and chopper comment but the easiest way to descibe it i feel is a bit of trade off between airspeed and rotor speed, that being when i go to BOMB some cattle, in doing so losing nearly if not all airspeed but using the momently lag of time for the rotors to nearly over speed and in most causes gain or at very least maintain height, while the motor is on full noise plus some if possible to get me back the airspeed that i just lost, but i'm no expert or done it as many times as the others on here, so that is just my very limited version of what i think happens.

[barnstorm2]

Bones: Is this what you were looking for?

After thorough preflight you taxi the aircraft to the runway. If there are people in the vicinity you will keep the rotors from spinning during the taxi with a rotor brake until you are clear of them. If you allow the blades to spin while you taxi your ground speed may not exceed normal walking speed and your rotor RPM (rrpm) must be greater than 100 rrpm. If you don't do this you could be the victim of blade flapping. The result is uncontrollable rotors and a craft that flips over! (or worse, chops a tail off.. heads...) Avoiding this is so simple you don’t even need an instrument such as your rrpm gauge. Just look at the blades. If they are spinning so slow you can count them, stop or don’t move. If you can’t count the blade tips as they pass in front of you then you are OK*.

Now you are on the runway ready to take off. If you have a typical gyroplane (like me) you will have to do a running takeoff similar in appearance to a fixed wing take off. The rotor RPM numbers I will list here are for MY gyro. Your RRPM may not be the same. Referr to your instructor/mfg.

A running takeoff in a gyroplane is similar only in appearance to a fixed wing takeoff. In a fixed wing at the beginning of the takeoff roll you go right to full throttle and remain there until you reach pattern altitude.

In the gyro takeoff you first pre-rotate the blades to 100 rrpm. Then slowly bring the cyclic back (tilting the rotordisk to the back) so that the prop-blast will spin the blades up to 150+ rrpm. The blades are now a blur from the pilot’s perspective. Now you can begin the takeoff roll but not at full throttle! As you proceed down the runway (cyclic still back) you slowly increase the throttle. As you reach about200 - 250 rrpm you can proceed to full throttle and slowly bring the cyclic forward. You will know when you reach this rrpm because the front wheel of the gyro will come off of the ground and you will be balancing on the main wheels. When your rrpm reaches normal speed, and your airspeed is correct you will pop-off off the runway and are airborne. Continue to build up airspeed before attemping to climb steeply or turning. (consult your instructor for airspeed mangement on takeoff for your gyro)

As you make your turns in the pattern you will not use the rudder pedals*. The rudder pedals are largely unused in gyroplane flight. Primarily they are needed for minor trim or for doing hot-dog maneuvers. You will turn with the rotordisk using the cyclic.

As you turn base and final you will cut your engine back to idle or some pilots even turn the engine off completely :eek: . Yes I just said you will cut the engine to idle*. Proceedures may be differn't if you have a crosswind or windy day. Consult your instructor on landing proceedure details this is just a 'readers digest' description of a landing! You are an autorotating gyroplane. Make a steep or shallow descent (your choice), then when you are a few feet above the surface* bring the cyclic back to reduce your airspeed to zero as you reach the ground touching your tail wheel first. The main gear will now automatically settle to the ground with zero roll. This creates a sensation like sitting on a big marshmallow.
You have now flown the pattern in your gyro! :D

*It is very very important to know the correct flare hight! Don't judge rotor RPM until this topic has been covered by your instructor! Engine throttle settings my differ! This is only a basic discription NOT to be used as a training guide! :mad:

DO NOT TAUNT HAPPY FUN GYRO! :mad:

[barnstorm2]

LJ,

BTW, I am not 'yelling' at you in the end of my post. I just don't want some ya-hoo tryin to fly based on my descriptions above or getting nit-picked cause some gyros use other procedures.

I know this seems crazy but I have read at least two FAA reports where people have had the trainer not show up for the first lesson and they tried to start or fly the gyro by themselves.

I think you wanted a 'from the cockpit' run through less specific details and that is what I tried to provide above.

[ventana7]

Tim,

That was an excellent description.

Rob

[ElJay]

Ya SEE!! Now thas what I'm talkin about, Instant gratification! Thanks Rob, all this helps and it is sinking in, but I REALLY feel like a new guy to the bone! (course I am).
LJ

[ElJay]

Again EXACTLY what I was looking for. The Real world. Well, I still have to rebuild machine 1st. I intend to do exactly what the manuals say (the old original bensen B8), build it as the "flying trailer", practice practice and then after I learn that (basics I guess, turns takeoffs/landings)
build it as the "flying glider" and practice some more. Only then, I will start looking at engine power etc, as long as I still have the urges strong (like I think I will). I figure that as I get the engine research started I'll find an instructor. Do ya'll think that is a good course of action or do you think I should modify/change it?
LJ

[bones]

How do you know "what" rotor rpm you have at any given time and what are the critical numbers, for takeoff, normal flight etc. I assume that the faster forward you go, the faster the rotors turn, which would increase or at least maintain altitude.

Sorry for the confusion Tim, but it was this part of the question that i was trying to answer that is all

[ventana7]

LJ,
IMHO the VERY first thing you should do is spend time with an instructor and some other pilots - hopefully from a nearby PRA chapter. I would not sit in the thing without some instruction.

Rob

[birdy]

Giday LJ,
The only time you need to manage RRPM is when take'n off.
Once your off the ground they do it [RPM regulation] all by them selves.All you have to do,and all you can do is keep them loaded.
As far as the RRPM on take off goes ,I could't say for sure coz I'v never had a rotor tack.But for some reason I seem to be able to git my machines off quicker than most other people.See'n as I don't have a tack,I must be do'n it by "feel".[just don't ask how,coz I don't know].

[Chopper Reid]

Rotor revs are going to vary as different sized and weighted rotors have different chararistics, also, the weight of the gyro has an affect as well as the density altitude comes into play.
Smaller the diameter rotor, usually the quicker they spin and the less weight they will carry. On my gyro, the 27 ft alloy rotors run at 350 revs and I have seen them rev to 420 revs during a tight diving turn. My 27 ft 6 in Glass rotors [tapered and twisted ,Rob Patroney 's] rev at 310 and dont fly as well as the alloys at max all up weight yet they fly better at less weight. I havent had the chance to see the max revs yet in the glass rotors . The glass rotors tend to hang on longer but they are heavier than the alloys by a few pounds.

[barnstorm2]

Thanks Rob!

Birdy and Chopper have it. You only have to watch Rotor RPM on taxi and takeoff. After that it is all 'automatic'. The way to avoid rotor decay is to fly like you were trained. Don't get into PIO and NO NEGITIVE G's. The rotors through the joy of physics will take care of speeding up and slowing down as they are needed to automaticly.

A great place to learn more is Paul Abbots books on gyroplanes. He goes into a clear and through discussion on how the blades 'auto manage' themselves through the various types of flight.

[Aussie_Paul]

...handy for 2 reasons. (1) for a normal recreational pilot you can work out the rrpm that you can apply full power without the fear of high speed rotor flap. This allows shorter take offs if you really need to get flying as quickly and as short as possible. (2) for instructors, the theory of unloading and slowing down the blades can be seen happening with a good rotor tacho.

I was conducting emergency procedures with my latest student Graeme, a few days ago, before he went solo. Graeme was a little unsure how hard you can push the nose down when you are a little slow and the engine quits. I demonstarted one with the nose high, the airspeed low and with 3/4 power, snapping the throttle closed. Graeme was surprised at how quickly you can push the stick forward. I had Graeme practice a few, and then I did another one having Graeme watch the rrpm tacho. The rrpm that day was running around 320, and when I pushed over, the rrpm reduced to 295 before climbing back up to normal rrpm in an approach attitude and airspeed. Graeme mentioned "Of course you can't have a PPO without the power."

Naturally experienced gyro pilots just know the "feel" of what they have availible from their rotors. As is usual for me, this info is aimed at the newbie inexperienced gyro pilot.
The point that I was making to Graeme was "how long it takes to regain rrpm for a landing flare." I told him to appreciate my advice of the dangers of being too low and too slow. It is all fine until the engine quits!!!!!!! :eek:

Aussie Paul.:)