Mt 03....

JRB549

J.R. Brown
I caught a gyro on the Animal Channel last night that looked just like this one look. Any ideas it was in south Africa
 

rtfm

Gold Member
Any comments on the roll axis being to one side??

Aussie Paul. :)
Hi,
I took a photo of the rotor head during the recent Dannevirke fly-in (North Island, NZ) because it looked so weird, but I couldn't get it off my cellphone. I asked about it and was treated to a novel sounding explanation, which went something like this...

"Since the advancing blade experiences a greater airspeed than the retreating blade, there is assymetry of lift, which tends to roll the gyro to the left. By offsetting the axis, this tendency is overcome".

Which is why most gyros fly round in circles, I guess...

One would have assumed that the designers had heard of flapping, but perhaps I'm missing something?

Regards,
Duncan
 

gyromike

Administrator
Staff member
Hi,
I took a photo of the rotor head during the recent Dannevirke fly-in (North Island, NZ) because it looked so weird, but I couldn't get it off my cellphone. I asked about it and was treated to a novel sounding explanation, which went something like this...

"Since the advancing blade experiences a greater airspeed than the retreating blade, there is assymetry of lift, which tends to roll the gyro to the left. By offsetting the axis, this tendency is overcome".

Which is why most gyros fly round in circles, I guess...

One would have assumed that the designers had heard of flapping, but perhaps I'm missing something?

Regards,
Duncan
I wonder what the explanation would be if they offered an engine that spun the prop in the opposite direction?:rolleyes:
 

Aussie_Paul

A reforming stirrer!!!!!
Ernie offsets the roll pin through the U block by a small amount. I understand that it is to have the airframe hanging against the prop torque.

Aussie Paul. :)
 

enewbold

COB Senior Member
"Since the advancing blade experiences a greater airspeed than the retreating blade, there is asymmetry of lift, which tends to roll the gyro to the left. By offsetting the axis, this tendency is overcome".
Thanks, Sam. Now I see it. The offset doesn't rotate; it's static. Interesting. The theory put forth earlier now makes a little more sense to me. =Ed=
 
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bpearson

Senior Member
Same as the Rotax Magni. I think in another post Doug Riley said he didn't like it. Funny that my Subaru Magni doesn't need it.
 

C. Beaty

Gold Supporter
The sideways offset levels the airframe against engine torque. Some Cierva Autogiros used a sideways offset of the rotorhead for the same reason. But with a prop speed of 1700 rpm and a couple of hundred HP, torque level was much higher.

Ernie’s offset of the roll pivot reduces the need for sideways stick pressure against prop torque but isn’t enough to have much effect on airframe leveling.

Cierva’s later designs employed differential tailplane lift to balance engine torque and to level the airframe but that requires tail surfaces centered in the propeller slipstream.
 
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Doug Riley

Platinum Member
Didn't like what? Using the rotor to offset prop torque?

It's not the best way. In low G at full throttle, the prop torque is still there, but the offsetting rotor thrust isn't.

The Cierva tailplane idea is a more reliable anti-torque device. A full-span vertical fin can be used the same way.
 

John Fonseca

Junior Member
I think the ELA has the same set-up. They claim you need no correction to torque as you lift off. I don't know, I've never flown either.

John Fonseca.
 

steveb

Member
It works ...

It works ...

The offset works OK. Most MTs seem to have a tendency to want to roll to the left in flight, so need a bit of right-stick pressure in the cruise. It's not a big deal as the stick forces are quite light. It also needs some right stick on take-off.
 

C. Beaty

Gold Supporter
The offset works OK. Most MTs seem to have a tendency to want to roll to the left in flight, so need a bit of right-stick pressure in the cruise. It's not a big deal as the stick forces are quite light. It also needs some right stick on take-off.
Sounds like it might be teeter bearing friction. Metal-on-metal teeter bearings normally try to lay the stick over to the left, forcing the pilot to hold right pressure.

Teeter bearings should be either Torrington style needle bearings or DU style plastic lined bushings.
 
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