prerotator clutch

[asra]

I know that the RAFs have a friction drive set up on them, but my question is has any one tried an electric clutch is in off an air conditioner compressor, two thing that come to mind as negatives, 1- will it be able to handle the torque required, and 2- would it be too severe when it cuts in, however that one could be over come with abit of belt slip or something like that.Any thoughts on this one..Mark

[birdy]

I have pondered it befor and thats bout as far as I got.Reckon you'd be battle'n to git enough pressure.Could be rong tho.First time for everything.Ignorance is bliss............but only till you realise you were.Ingratitude stinks.......be generous carefully.

[asra]

looking @ some gyro's and if you use a spring loaded clutch like a chain saw clutch which dosen't engage a low rev's and use a a/c clutch to engage the chainsaw clutch so the prerotator can disengage once it is spun up.just my ramblingstwo things to consider.1 the clutch has to engage and disengage.2 the clutch has to ease into power ( chainsaw clutch whitch is also cheap)and just thought of another thing to consider weight.if you use a flex drive to the hub from the motor it is simple and a belt from the motor say the altenator belt can accomodate a a/c pulley and put a chainsaw clutch in there to smooth the power given ????? or even a small hydrostatic torque drive from a washing machine (like a stall convertor in a car auto.???friction drive of the flywheel seems to be the simplest so farjust some ideasSmithy

[asra]

All this pre-rotator discussion comes back to a decision on what RRPM you want, and so how much power you need to transmit.For most situations 70 or 80 RRPM is sufficient, and doesn't take a lot of power, in fact the Butterfly hand powered one may get something approaching this. I built one using a pull start from a Briggs and Stratton mower - the one that pulls straight up, invertd of course, but it was too high geared with the gear I cut for it, and that was the biggest gear I could fit in. Butterfly appears to have a further stage of reduction. I will watch it with great interest.John EvansThink logically and do things well, think laterally and do things better.

[asra]

I agree John. Below is a few of my experiences and views.Heck back in the 80's we were qhite happy to hand start the rotors, because the Wunderlich was over 1,000 bucks!!!! I would have died under a rolling pin if I had spent that sort of money with a young family!!!![:0] I know I know, you would not have to put up with me now!!!![]The starter motor, rotating the correct way, came along with the east west engined cars, and away the boys went in developing that.[] The down side has always been the shock loading and as the ensuing years with successful operation of hours, start ups, etc we accept that shock loading. That is how I see it, for what it's worth.Anything over 60 or 70 rrpm (excepting for DWs I guess) is acceptable for most recreational flyers.[^]I would think the simplest lightest cheapest and reasonable effective pre rotator is what most recreational pilots probably want and or need.[?]The next level is with my Firebird requirements, the musterers and station people who sometimes really need a GREAT pre rotator. This is the real challenge at the present time.We need a minimum of 170( depending on rotor type and engine hp) to conduct a fixed wing style of take off, ie full power from when the wheels move.The Magni I tested at MTOW went like this. Pre rotated to 230 holding with brake, let the brakes go and hit the turbo fully, and then released the pre rotator. I was in the air before I could count to 4.[:0]In that scenario, as soon as you can accelerate the gyro mass to take of speed you are airborne. It was certainly a great feeling.[] I did not stress the pre rotator and believe that there was possibly 20 more rrpm availible. I have a pic of the Magni gear up at the head. I must have a look and count the teeth on each cog. The rotor brake is an integral part of the pre rotator.Ok, the end of my pre rotator ramblings[:I]Aussie paul. []www.firebirdgyros.com

[asra]

Keep going Gentleman. I want a minimum 200 RPM and I'm not afraid to spend my wife's money to get it. Gyros had pre-rotator in the 1920'S I kind of thought it would all be sorted out by now.Daryl Patterson

[asra]

G'Day all,My experience with the Magni in Europe is; Pre-rotate holding with brakes to 180rpm. Continue, increasing engine speed and bringing the stick right back, putting the blades into prop blast and balancing rotor thrust with prop thrust, At 280rpm release brakes and then prerotator, moving stick forward for quick accelleration to lift-off.Fish.

[asra]

Dear Southern Hemisphere collegues: You don't need a prerotator, neither a brake, to prerotate to 200 RPM.La Cierva used to spin rotors with a drum (You can use an empty rim) with a rope (A strong one!!) tied to a stake in the ground.You, pusher style propeller, must redirect the rope with a couple of pulleys to the stake, or if you prefer, to another empty rim attached to one of the main wheels.Prior to take off, you disengage the bungee cord of your blades (The rope is rolled in the drum)and insert the knot hanging in your keel in the receiver slot of the empty rim. Then, slowly you accelerate, watching the line you follow, because the tractor tire make a strong force to deviate your path.The rope (10 Mts) are inside a piece of PVC tube, to avoid interfere with the prop when let go from the upper drum. My friends called it "The Maffia Prerotator". I hope will be usefull for yoy.Sorry my bad english.regards.Edgardo Maffia - PRA Life MemberBuenos Aires - Argentina

[birdy]

Any translaters on this forum??That sounds interesting.Ignorance is bliss............but only till you realise you were.Ingratitude stinks.......be generous carefully.

[asra]

Paul, Can you post the picture of the Magni pre rotator.Daryl Patterson

[NiqueNaque]

The rope idea works, until your next destination...

[asra]

This is the drive section Darryl.O.B. Aussie Paul.l[]Image Insert: 60.09

[asra]

Thanks Paul. Am I right in assuming that the other end is engaged and disengaged also? Do you know the approximate gearing ratio at the other end?Daryl Patterson

[asra]

Hi Darryl, yes the other end has a bendix arrangement. The ring gear is 108 or 109 teeth and the pinion I think is 9 teeth. Someone else may know and point out if I am incorrect!!! Remember I am never wrong just incorrect a lot of the time!!![]O.B. Aussie Paul. []www.firebirdgyros.com

[telf]

Hey Paul,Can I assume that 'O.B.' in your signature means 'Old *******'?Did you get that many new grey hairs training me this week??telf