Calidus

[mad max]

Yep, I like a pre-rotator that you can keep engaged for a while even when rolling with stick hard back. I also like the simple control system where you can feel rotor shake before it goes out of control. You certainly need a rotor RPM meter on these modern ships.

[RickE]

The pre-rotation technique that I use in my mto is to get the engine revs to around 3200 which equates to around 200rotor rpm and leaving the throttle where it is pull the stick back slowly and gradually increase the engine revs. The Calidus and the Cavalon use the same principle.If I am on a busy airfield I would pull the stick back at 100rotor rpm and build the rotor speed up during the takeoff roll to get out of the way as soon as possible.The Magni"s pre-rotation is a bit different as they pre-rotate to 130rpm and then pull the stick back and finish off the prerotation with the stick fully back generally to around 230rpm.I can see the advantage of being able to prerotate with the stick fully back but touch wood I haven"t had a problem yet.

[Disco]

Rick, Wouldn"t it be quicker at a busy airfield to rotate to 200+ and **** off instead of 100 and doing a slower roll away?

[RickE]

I guess the difference is that you can spin up to 100rpm with the engine at idle while at the holding point and then enter the runway without stopping for prerotation.But whether it"s actually faster or not I"m not sure it just seems to be a better option than just sitting there prerotating while there is traffic in the circuit.

[MadMuz]

The problem that always springs to my mind with stick forward prerotating to stick back and floor it.... is that when prerotating, the rotors are obviously being driven (in a helicopter state) once you stop prerotating, stick back and gun it, the rotors need a few moments to realise that they are no linger powered and need to get autorotating asap... but you cant force them to fly until they have airflow going up thru them, instead of being pulled down thru them. What the others are saying about needing to prerotate with the stick back and increasing speed is right, imo, the forward movement and the rotor seeing the airflow from the angle that it will need to autorotate will make the transition from driven to autorotation almost just a blur.... almost instantaneous, especially in low or no headwind situations...The rotor has to be flying before your machine will.... tffs!

[JAL]

The problem that always springs to my mind with stick forward prerotating to stick back and floor it.... is that when prerotating, the rotors are obviously being driven (in a helicopter state) once you stop prerotating, stick back and gun it, the rotors need a few moments to realise that they are no linger powered and need to get autorotating asap... but you cant force them to fly until they have airflow going up thru them, instead of being pulled down thru them. What the others are saying about needing to prerotate with the stick back and increasing speed is right, imo, the forward movement and the rotor seeing the airflow from the angle that it will need to autorotate will make the transition from driven to autorotation almost just a blur.... almost instantaneous, especially in low or no headwind situations...The rotor has to be flying before your machine will.... tffs! But as Rick E has already said that"s not what you supposed to do. MTOsport pilots in oz are not taught to pre-rotate then floor it. They are taught to pre-rotate then go to about 4000 rpm wait for the front wheel to come up then floor it. You are not supposed to go to full throttle until the blades are fully flying and above 200 rrpm. You must achieve a wheel balance first before going to full throttle, the more experience you have the quicker you can complete the sequence the shorter the ground run but you are not to go from standing start prerotation straight to full throttle. Not sure why they seem not to be taught this in Europe, maybe they are its just that pilots are doing it anyway because it can be done and 99% time it will work.I can see there is some good benefits of being able to prerotate with the stick back because you could engage it while in the takeoff run reducing the chances of flapping and getting off the ground quicker but I think the biggest advantage is being able to engage it while taxiing when required , especially when taxiing downwind on a rough runway restricting ground speed to less than what is required to keep the blades rotating above the 100 or so rrpm to avoid flapping.It is a pain in **** in the MTO that you have to move the stick forward to add some prerotation while taxiing, normally on a windy day on a rough runway you end up taxiing the entire length of the runway with the stick forward and prerotator engaged requiring the prerotator to do all the work with no help from the wind adding unnecessary wear, if the prerotator could be engaged while the stick is fully back it would get some help from the wind and would only require shorter bursts to maintain rrpm if the taxi speed cannot be fast enough to sustain it.

[mad max]

My rule is never floor any gyro untill you feel the nose getting light.

[MadMuz]

Jal, I am just talking about what is in "the manual" I read a copy of the takeoff procedure from one of the euros and it just said that line up with centre line, prerotate to 200+ rpm then brakes from park to flight, stick back then slam the jandal.... (oh, sorry, that was the NZ version I guess) ;DI know that with Mork in charge of training here in Aus, the proper procedure and plenty of knowledge of proper rotor handling would be taught, you can bet on that. My point is that prerotating is made difficult and "unnatural" for want of a better word, to have to have the stick right forward (even into the perfect headwind) for the reason I outlined above.On the taxying downwind, the manual also stated all taxying apart from take off run should be done with the rotors stopped

[RickE]

I have just read the takeoff procedure out of the manual for the MTO Sport and it states that once 200rotor rpm is achieved the prerotator is released the control stick pulled gently aft, the brake is then released with the throttle position unchanged. Monitor rotor speed and adequately increase throttle to takeoff power.I would be interested to know which of the Eurogyros takeoff procedure calls for full power from the start of the roll as I agree Muz sooner or later it will end badly.

[birdy]

Like i said, if the prespinner can stay engauged till the wheels are off, you can got strate to WOT from the start without fear of flapn. No chance of stressn the rotor, and off in feet, not yards.

[RickE]

Wouldn"t having the prespinner connected until lift off damage it? I fly a Cavalon which uses a clutch and gearbox for the prerotator and the maximum I can get that up to is 220 regardless of engine revs. Not sure what would happen to it even if I could keep it connected until takeoff.

[mad max]

I just feel some people may be playing russian roulette with their blades flooring the gas before they feel the nose getting light. High speed rotor flap can be devastating to the pocket. The craft goes completely out of control and often destroys itself. They usually shoot off the runway and a collision with something else is also possible. :"(

[MadMuz]

Like i said, if the prespinner can stay engauged till the wheels are off, you can got strate to WOT from the start without fear of flapn. No chance of stressn the rotor, and off in feet, not yards.That"s funny that you say that Birdie... I have never seen a euro tandem machine do anything like a short takeoff, every one I have seen do a takeoff, has always been a long, drawn out takeoff run, where I am thinking, "it will eventually lift off wont it?" All of the ones I have seen in person, and all of the videos I have seen, they all seem to sort of "labour" into the air.... like tat blue one in England that struggled off the ground then got behind the power curve and landed/balled up next to the highway..... they just don"t seem (from what I have watched) to be real sporty or performance orientated? For example, at Wondai at Easter, where Mork did about a 10"takeoff in the sport copter, nearly wound the rotor off of it with the prerotator on the spot, then launched it in like about 10"maximum..... real impressive, but the euro clones seem to take for ever to get off, even one up?I agree, when the prerotator can be used on the run with the stick back, short takeoffs are very achievable.... the more headwind the better, the airflow assists the prerotator.Can the Calidus prerotate on the run with the stick back?

[birdy]

Wouldn"t having the prespinner connected until lift off damage it? Not if its built to do it.Bin do,n it for years, on two different machines, and never hada issue.Prespinner still driven 10 seconds or more after breakn ground, climbn near virtical.

[MadMuz]

That"s what the bendix is for Rick, so once the rotor speed overtakes what the prerotator is dishing out, the bendix disengages and drops down out of harms way.... but like Birdy says, only if your setup is designed that way. If your manual tells you to do it another way, you have to go by the manual, unless you are sure it is safe to go against the manuals method.