Hi,
I was wondering at what sort of rpm a rotor starts to lift when the gyro accelerates on the ground ?`
I'll tell you later the reason of my question
thanks
G

Good question - I'm just helicopters - I know at idle we get a bounce in the rotors
Enstroms with the rotors slowly turning 30 to 60 rpm it will 'bob' on the skids fore and aft
The Bell 206 will bounce at slow idle unless you add a little collective
and the Huey in stiff winds when starting will rock the mast

thanks H,

I will set up a cam on the gyro filming both the rotor tach and the runway

I would like to see if it is possible to keep the electric motor power (up to Say 220 rpm) during the acceleration of the gyro,

after 220 rpm the rotor would accelerate over 220 rpm without producing any torque

in other words if the pre-rotator MOTOR maintained at a constant and max speed under the flying RPM mother nature will decide cut the torque just before the gyro will take off.

G

Each machine and it's set of rotors will have a different speed of the rotor that lets them carry the machine. The same machine and rotor combo will have differing speeds of rotor due to air density, altitude, weight of the machine etc. I have always used the prerotator to get the rotors over the 'hump' speed.... so that aerodynamics can take over and the blades increase their own speed.

I wouldn't like to have rotors engaged to any prerotator at flying speed? To me, it is risking something binding up if things were to go wrong somehow... I like the fact that the rotors on a gyro do their own thing... as long as the rotor is free to turn, the machine can fly KISS (Keep It Simple Stupid)

Mad Muz,

I am just thinking don't worry,

But ... first of all the brushless motor spins the rotor but the rotor can't spin the motor (free wheel)., there is no gear, no bendix, only a timing belt, nothing can get blocked .... I mean it is not a bendix/crown gear system

the pre-spinner would only launch the rotor to 220 with an electronic system that would drive the motor, when the rotor will accelerate, the pre-rotator will not be engaged because it will turn slower then the rotor .. it won't exert any torque if the rotor spins at more then 220 rpm

so the question ... does the gyro already flies when the gyro is rolling with it"s rotor at 220 rpm ?

I don't thing so

it is just speculation MM I don't recommend anybody to do this and my pre-spinner will work when chicks have teeth ... so don't worry to early for me (((-:

JUst FYI, On my Tango I prespin to about 170 with 28ft blades, I can spin up to about 210 but the rotor decays so fast that it drops back down to about 180 or so before it starts to gain speed, so I prerotate to 170, start takeoff roll, go to 3/4 power at 200 rrpm, the nose lifts at 220 rrpm, then full power and I am off a couple seconds after that.
about 500 ft. about 700 ft with passenger, From grass.
Hope this helps.

Geezus Christ Els, you obviously haven't been listening to "Rabid Abid" on the other site! Your supposed to pull stick all the way back, rotate to like 500 rpm and blast off !

Yeah well.........you know.....

Yeah... the book says "prerotate until the machine lifts off the ground, then stick full back and fly away at warp factor 9 "

You don't need to know anything but that... happy flying

I don't know those book MM, the point is that I can pre rotate as much as I can it never lifts my gyro nose when I have the stick ahead .. it never happened to me .. maybe a bad position of my main wheels that are maybe 2 inches behind the rotor head (horizontally of course hahahah)

my stupid idea is to work on the helicopter/auto-rotation modes transition by powering the rotor a short time after the pilot has released brakes and pushed the throttle

of course this is absolutely not something to be attempted with a mechanical pre-rotor and before a really good test pilot has spent time testing different procedures in the goal of trying to find something "new" in order to take all the benefits of an electric pre-rotator

the transition btw heli mode and auto-rotational mode consumes a lot of rolling distance, the idea would be to automatise the process by creating a RPM ceiling of pre-rotation powering to soften the transition, and make idiot proofed .

in this case the rotor would never loose rpm and would be powered by the electric motor until the rotor rpm exceeds 220 rpm providing a soft helicopter/auto-rotation modes

there is a clear illustration of the effect of this transition in the case of the jump-take of of Michel cross

it appears clearly that even after an hard pre-rotation of 450 rpm the gyro jumps, then the pilot applies full throttle but the gyro looses altitude and nearly lands again before flying away

the reason is nothing then the abrupt transition from the heli mode (when the rotor is powered by it's inertia after the pre rotator is disengaged) to the auto-rotational mode

the idea would be to try ...only to try to find a softer transition using the capacity of an electric prespinner to power the rotation without any variation until the transition is done ...

of course .. the gyro must not begin the fly at 220 rpm and the airspeed produced by acceleration ...

this is the reason why I need to film my take off from the cockpit with a view focused on the rotor tack with also an outside view to see the rpm at the moment the gyro lifts it's front wheel ..

an other method would be to forget the full back stick position ... as a mater of fact this is only used to finish the rotor rpm build up to the flight rpm (320 rpm for me)

if the pre spinner is able to spin the rotor up to 300 rpm stick ahead, it could lift it's 3 wheels with the rotor at the flight angle (7°) ...
this is something that can't be done today because when people on magnis are pre-rotating at 300 rpm it withdrawn so much power to the propeller that it prevents to get a proper acceleration ...

problem is torque of course .. because in this case the gyro would definitely take off before the rotor reaches 300 rpm ...

ok it is pure delirium ... hahahah for the moment my pre-rotator un 70 rpm capable hahaha

I have seen plenty of noobs chop the tail off and ruin blades by pulling all the way back and then spinning..(er pre-rotating to us old guys) ..
Stick forward, pre rotate, blades back as you start your roll, and then manage your rrpm on your roll with throttle/speed..once you get a feel for it it is as easy as getting used to starting from a stop using a clutch on a motorcycle....really a whole lot going on at first when you are not used to it.

Hi,
the bottle does not matters as mutch as the drunkness
as long as we are all using a safe methods that works fine all is ok
here in france, except for the pioneers who had ineficient car starters pre-rotators, everybody spins stick ahead and then , stick fully back and push the throttle fullly in a slow motion , when the front wheel begins to lift or a bit before stick ahead , acceleration to vx at one meter above runaway and ascent ..
I don't say that it is the right method, but this is what we all do
it comes both from the fact that we all have 220 to 300 rpm capables pre-rotators (no flapping hazard at this rpm's), and from the fact that we have short grass runways on which it is really not good to stay too long and too fast (it shakes the mast
nobody has never flapped his blades this way, only the ones who forgot to put stick back , accelerated hard and suddently put stick back have flapped their blades in fact.
I have never managed my rrpm after I realeased to pre-rotator pedal, I watch the rotor tach when I pre-rotate, when it is at 250 rrpm I watch outside and never watch the tach again
I would not be able to take off hand launching my blades ..

I never had a prerotator on machines with Gerry Goodwin blades... I could give 2 or 3 good pushes by hand and have them up to speed in no time... only had the stick starting to 'stir' a few times on very still or very windy days... the only time I needed a prerotator was with Boyette blades... and then it was just to get them over the hump.

All of my prerotators were car starters... they were simple and all I needed. I will be moving some stuff in my storage soon, so will take some pics when I do

Get rid of the pre-rotator, you will get rid of the pre-rotator issues !
the simpler the better,
the ligther the better !

how heavy were those Gerry Goodwin blades ?

Not sure Giro... just average weight for blades at the time. They were a straight, flat bottom blade, all bonded... the hub bar was twisted... just bonded, no rivets, the straps stayed on the blade.

If you can see on Mad Max 11 the blades on that gyro were Gerry's (and he flew the gyro)

"Dat's how its done boiiiiiis!!!"

You know you could offer this gem to all them schmucks making gyros and the money they could save on printing ink of their POH would be something!

Part 2: once nose wheel starts to come up, gently lower and add full throttle if not already there, let gyro fly up on its own when ready. As soon as you get up say 3 to 5 feet position nose down just a skosh to fly in "ground effect" and pick up even more speed, then pull back on stick to gain altitude.

once you have reached 100 feet or so, feel free to glance at the rotor rpm gauge if you like.

Thx for this video I had not seen it for years ,

I was young (15) when I saw this film for the first time, I remember that I had not been able to sleep until I could get the max max 2 VHS K7 ... when I got it I spent hours and hours watching the short footages of the gyro ... this is the origin of my obsession for gyros ...

as for bonded rotors, I wonder if some are still produced ? and if they could be tuned to zero perceivable vibs like the averso extruded rotors ?

Benry.. Thanks for part 2.. The only thing I would add, is that some people like to keep the nose wheel down, and others like to balance on the mains...The reason I like to balance on the mains is that it keeps the rotor loaded, if you drop the nose wheel back on the runway it is easy to accidently lower the blades too much and loose their bite, and not get up to flying speed, so when the pilot yanks the stick back he will flap the blades.

When balancing on the mains I go to full power when the nose wheel comes up, keep it balanced and it flys right off the runway, no back stick needed, then lower the nose slightly after takeoff to gain speed before climb out.

I have flown with fixed wing pilots that think they need to jerk the aircraft off the runway also, if you let the aircraft fly when it is ready, you will not have blade flapping, behind the power curve, type accidents,

lets think a bit,

why do we accelerate stick back after pre-rotation ?

why do we balance on mains (for those who do this) ?

the reason is : finishing the pre-rotation before setting the rotor at flight angle (7/8°) to leave the ground

but acceleration stick fully back or balancing on mains consumes runway take off distance.

then imagine the pre-rotator is able to launch at flight rpm sick ahead and is able to self cut

imagine that once at 320 rpm the pilot simply puts the stick neurtral (rotor at 7°) and push the throttle ?

what would happen ?

the gyro would take off shorter ..

Not always Giro... unless it is a jump gyro...

A gyro prerotating is turning the rotor with the air coming down through the disk, like a helicopter... once one pulls back the stick, the airflow has to change from going down through the rotor to coming up thru the rotor (autorotating)

I have seen people in tubs rotate to the number in the book and then 'stick back and full throttle'... and still take hundreds of meters to get airborn. My old car starter pre rotators I could use with the stick back.... into the wind, even dragon wings would get going fairly quickly because they are also using the forward movement and its resulting airflow to get to flying condition.

I don't think tubs are allowed to prerotate with the stick back are they? If their prerotator malfunctions, the machine is grounded isn't it?