Calidus - N507PF - Blum Texas

Even solo here at 3100' MSL I see 400 rrpm.

Abid, you need to get your gyro rating. You have a whole forum full of people rooting for you. No excuses!
 
Cammie Patch;n1123243 said:
I see the 8.4 blades cruise at 450 rrpm on a regular basis.
Lift can be achieved by angle of attack or airspeed. Since a blade cannot adjust its own angle of attack, it must increase its speed to maintain lift.
TL:DR RRPM is a function of density altitude and weight.

I agree, my Cavalon is consistently between 420-460. My MTO was less but on hot, humid, heavy days it would be in the high 300's.
 
The power consumed by rotor profile drag varies as the cube power of tip speed, everything else remaining constant. That means for a doubling tip speed, the power required to drag the rotor blades around in a circle would increase by a factor of 8. A 10% increase of tip speed would increase power consumption by a third (1.1^3 = 1.33).

Tip speed is approximately equal to: 66 x square root of blade loading at sea level air density. (blade loading, not disc loading)

(pounds, feet, seconds)
 
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magknight;n1123385 said:
I agree, my Cavalon is consistently between 420-460. My MTO was less but on hot, humid, heavy days it would be in the high 300's.

To what do you attribute the difference, simply a weight/load difference? I'm assuming you have similar blades on the Cavalon to the MTO
 
I'm surprised with this discussion. I am currently flying an 'eurogyro', an ELA with a 8.5m rotor, and the RRPMs do never surpass 350 in s/l flight... It's true that I use to fly alone, but my airfield is at 3000 ft, and we're having a very hot summer here...
 
Cammie Patch;n1123378 said:
Even solo here at 3100' MSL I see 400 rrpm.

Abid, you need to get your gyro rating. You have a whole forum full of people rooting for you. No excuses!

I will though that won't make me fly a gyro any better or increase my understanding Cammie. Its a matter of taking a checkride one of these days to add-on. I am busy enough that my only solace is at night. You ought to give different rotors a try sometime. AR-1 at 7500 feet MSL DA is not even 400 RRPM solo.
 
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XXavier;n1123459 said:
I'm surprised with this discussion. I am currently flying an 'eurogyro', an ELA with a 8.5m rotor, and the RRPMs do never surpass 350 in s/l flight... It's true that I use to fly alone, but my airfield is at 3000 ft, and we're having a very hot summer here...

So am I but may be AutoGyro newer rotors do go above 400 RRPM even at slightly over 3100 feet solo as Cammie says. I believe her and Jason of course but guys that is just AutoGyro then. It certainly not all gyros.
 
My Sportcopter M912 does 330 to 360 RRPM solo :) depending on cruise speed and weight with extra fuel tanks full. Always have to keep my extra tanks full of fuel to keep up with Barry flying his Apollo. All the Trike fliers at my airport are starting have gyro envy.
 
fara;n1123498 said:
So am I but may be AutoGyro newer rotors do go above 400 RRPM even at slightly over 3100 feet solo as Cammie says. I believe her and Jason of course but guys that is just AutoGyro then. It certainly not all gyros.

I have a new Magni M24. I did some flight testing last week. At 1900 feet, 95 mph, solo pilot, and ground temperatures in the 90's, the RPM was 385. I have no doubt it would go above 400 rpm with a second person on board or higher altitude.
 
Europe uses the metric system. Their RPM's are probably measured in Newton Meters per kilometer. McCulloch J2 still wins in RRPM, especially in spin-up.
 
Brent Drake;n1123344 said:
Fara the Auto Gyro flys at about 400-+. All of models do. Even the Zenon does.

With the standard rotor at "normal" density heights, i.e., near sea level, they all cruise at around 360 rrpm.

-- Chris.
 
Brent Drake;n1123114 said:
I personally feel this need to be addressed more. When rotating to 200 RPM then full accelerating to full power is the root cause of these mishaps.

To get back to the original topic: I disagree with Brent. The takeoff procedure as stated in the POH works just fine. Mind you, I am not a fan of only doing it that way without ever having experienced a slow rotor or managed one during takeoff. But at 200 rrpm it is perfectl safe to take the stick full back and go to full throttle. This will give you the shortest takeoff distance.

The cause of the accident here was that the student put down the nosé gear again once it haf lifted off already during the takeoff run. Nothing to do with full throttle or not.

-- Chris.
 
ckurz7000;n1123895 said:
To get back to the original topic: I disagree with Brent. The takeoff procedure as stated in the POH works just fine. Mind you, I am not a fan of only doing it that way without ever having experienced a slow rotor or managed one during takeoff. But at 200 rrpm it is perfectl safe to take the stick full back and go to full throttle. This will give you the shortest takeoff distance.

The cause of the accident here was that the student put down the nosé gear again once it haf lifted off already during the takeoff run. Nothing to do with full throttle or not.

-- Chris.

I think the greatest danger of this technique is not the technique itself, but the way in which it is sometimes taught and applied, in a very rapid and poorly controlled fashion. Particularly with new students, this means that there is a lot happening in a very short time. Hence the nose comes up much more quickly etc, which may result in over controlling in the opposite direction by a neophyte, as appears to have happened in this case. If there is one thing to remember during takeoff, it's control of the nose wheel, the rest will take care of itself.
For this reason alone I believe the technique of learning the effect and interrelationship of stick position and rotor speed and aircraft speed on the ground is an invaluable training step, while feeling the lightening of the nose wheel, even if one does not proceed to full balancing on the mains. So I think the Autogyro POH technique is a perfectly valid technique, just poorly described in the POH and poorly taught.
The concept of smooth and controlled application, and retardation of the throttle, is something that was not emphasized enough in my training, and was a habit I actually had to unlearn when my hangar mate, a multi thousand hour gyro and heli pilot, pointed this out to me. Slow retardation of the throttle is also important to minimize the risk of the engine cutting when pulling back rapidly on the throttle. The throttle should be as gently controlled as the stick.
The other downside of this technique when applied in a rapid fashion, is the increased stress and resulting wear and tear on all the components.
 
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Agreed. Always use smooth inputs. And one should definitely learn to balance on the mains and do crow hops before doing any kind of takeoff.

-- Chris.
 
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