Wheel Spacings

[NiqueNaque]

Could be to get the back stick on the rotor..

[Tim]

Back when the Pitcairns and Ciervas flew, nearly all planes were taildraggers. The Little Wing and the Pitbull have both tried to maintain a nostalgic connection with the past, with the added advantage that they are easier and cheaper to build. There are other tricycle tractors, Jim Eich's JE2 and the Fairy Rotordyne come to mind, along with the later Pitcairns.Tim McClure

[asra]

Would there really be any disadvantages to using conventional gear on a tall tail, pusher design? Since visibility won't be a problem and control on the rollout is also a non issue on a gyro, the only thing that might cause problems is the take-off roll. Since most gyro take-offs are from the mains only, like most tail draggers, the only unfamiliar problem might be the yaw that occurs when the tail wheel lifts. I'm assuming that this is caused primarily by prop torque and p-factor, and they are mostly cancelled by a tall tail. The only unknown that I can see is any instability that might be caused by having the mains in front of the CG.It seems to me that conventional gear has serveral advantages for lead-sled gyros like the Sparrowhawk:Reduced weightBetter rough field capabilitySimplicityEasier entry and exit from cabin (the cabin will be lower to the ground)and very few, if any, disadvantages.What do y'all think?

[asra]

Well well well look at all this activity on the forum. Makes one think the Australia gyro scene is alive and has some real thinkers.Your turn now Russell, and no namby panby questions that only require a yes or no answer.Ted

[Tim]

quote:Originally posted by pwendellthe yaw.... is caused primarily by prop torque and p-factor, and they are mostly cancelled by a tall tail. G'day Peter. The yaw that you refer to is caused by screwing airflow from the prop hitting the side of the rudder. Your are correct in that it can be cancelled by a correctly set up tall tail, but it can also be minimised by a correctly set up offset conventional rudder.In all correctly set up machines, most take off and landing yaw problems are caused by X winds which do not have to be very strong to affect a short-coupled slow gyroplane.Just to pick up on another one of your points, "Easier entry and exit from cabin (the cabin will be lower to the ground)"In most taildraggers, the cabin is actually higher off the ground, and it would definately be the case with a pusher.Tim McClure

[asra]

Tim,How much of an offset and to which side?Ted

[Tim]

It varies Ted. The angle of the slipstream depends on the propeller speed, pitch and airspeed. Setting the fin angle at 9 to 12 degrees is a good starting point for a conventional rudder and from there it can easily be trimmed with a small trim tab.on a Rotax 2-stroke the forward edge is offset towards the RH side of the keel and on the Rotax 91X series it is opposite.Tim McClure

[asra]

Tim,Is it also designed this way to enable very positive effect whilst the prop is not at full rpms? As in on the ground or low airspeed, and if so does this then correspond to an effect loading which then falls away in effeciency rateing around cruise speed or above?Ted

[Tim]

Ted, the reason why I built in offset in the rudder fin was that I had seen many Bensen style machines with straight fin flying and they had to use nearly full rudder on take off and about half rudder deflection in the air. Some even ran out of rudder on take off and had to abort before they ran off the strip, and have another go with more airspeed. It made common sense to align the fin with the cruise airflow, so that you could fly with neutral rudder and still have equal response, both left and right. A benefit was considerably decreased rudder drag which meant better cruise speed. A slight disadvantage was that you needed to use a bit of rudder (opposite the offset) on power off. This was no problem because there was plenty of rudder authority anyway.Tim McClure

[asra]

Tim,From reading your last post then can I assume that any decrease in power setting would have required a rudder input until actual cruise speed reflected the prop output, at which stage the rudder became neutral again?Ted

[Tim]

Yes Ted. Basically use rudder as required. In this case (RH prop) you have to use a little left rudder on take off (full power) neutral on cruise (cruise power) and a little right on power off. It is rarely that simple though because even a slight cross wind can change things.Tim McClure