New Magni M24

[gyrogreg]

Birdy - here is what you said:

Ya beet me to it Udi.
But, even if the blades were stiff enuff to hold the weight stationary, itd still be bad engineering to not have the cone angle set in the bar.

Maybe I took this wrong, but the subject was Magni gyro rotor, and this could be taken as a suggestion the rotor had "bad engineering". Just clearing the air if somebody else read it that way too!

 

[Udi]

Dang it all, Udi, force is supposed to be in Newtons (10^5 dynes), not Kg.

Yes - the formula calculates force in newtons and then the newtons are divided by G (9.8) to convert it to kg-f so I can find the tangent. Are you saying my units should read kg, not kg-f, or I should have converted the lift to newtons as well? I am an engineer - either way the result is correct

 

[Udi]

Huh - what do you know... I wasn't wrong after all...
http://en.wikipedia.org/wiki/Kilogram-force

 

[birdy]

Dont be so sensative Greg.
I thought i was pretty clear.
I never even mentioned Magni.
I said, itd be bad practice, no matter who did it, to engineer stress into the blade system .

 

[Udi]

...But, even if the blades were stiff enuff to hold the weight stationary, itd still be bad engineering to not have the cone angle set in the bar.

Well, if we are going to be picky, your above statement is incorrect, Birdy. IF (IF) the blades were stiff enough to support the weight of the gyro, there wouldn't be a need for undersling because the blades would be able to run completely un-coned.

 

[C. Beaty]

Huh - what do you know... I wasn't wrong after all...
http://en.wikipedia.org/wiki/Kilogram-force

That’s interesting, Udi.

I’ve noticed that many catalogues; bearing manufacturers for instance, specify load ratings in lbs. and newtons. To be consistent, they ought to specify load ratings in poundals and newtons.

I don’t think I’ve used a poundal as a unit of force since finishing freshman physics. The spell checker that comes with my edition of MS Word hasn’t heard of either one.

 

[birdy]

We can be picky if we like to be Udi, but i think its good to stay realistic.

 

[Skyjinks]

Al - good to have you back :wave:

You have been away TOO long :boink:

Greg - there is NO WAY a rotor blade is stiff enough to support even 20% of your gyro all up weight. Do an experiment - hang the assembled rotor from both ends to a beam and then hang, say, 250 lbs from its hub... (I know you would not actually try this - I just want to illustrate why rotor stiffness is irrelevant to coning angle).

I must be missing something here!
No Way a rotor blade is stiff enough to support even 20% of all up weight. Agreed!! I just want to illustrate why rotor stiffness is irrelevant to coning angle Why is rotor stiffness irrelevant? Surely if the stiffness is sufficient to support the static load there is no coning angle. Assuming it is not then the CF will ameliaoate the situation dependant upon the stiffness?!! Stiffer blades will have less coning angle for any rotational speed and same underslung load.

 

[RotoPlane]

(Dang it all, Udi & Chuck)

Poundals:der:, newtons, dynes, kilogram, kilogram-force and all the other weird units you may come up with, could drive me nuts!!

American:usa2: units such as good o'l foot-pounds work just fine and one doesn't need a desk full of converting tables to come up with the final answer.

 

[mceagle]

Stiffer blades will have less coning angle for any rotational speed and same underslung load.

The coning angle is only a product of centrifugal force and load - blade stiffness is irrelevant. There has not been blades built yet that are stiff enough to overcome those forces. Even a "stiff" blade will bend/flex up to assume the correct coning angle.
Here-in lies a problem - if the blade is too stiff, then the blade or bar will bend to the required cone and this is not good.

 

[gyrogreg]

The coning angle is only a product of centrifugal force and load - blade stiffness is irrelevant. There has not been blades built yet that are stiff enough to overcome those forces. Even a "stiff" blade will bend/flex up to assume the correct coning angle.
Here-in lies a problem - if the blade is too stiff, then the blade or bar will bend to the required cone and this is not good.

I think we have established that the shallow coning angle and the short undersling of the Magni rotor are reasonably consistent with the rotor weight, RPM and loading. I agree that, even though the blades are very stiff, that stiffness is probably not restricting coning.

Since we are looking for Magni "secrets" to stability, and since it has been suggested that part or much of the stability might be due to rotor dynamic DAMPING, I am questioning if the shallow coning angle, and the resultant lower coning angle and RRPM change with loading and maneuvering has anything to do with rotor damping.

Rotor damping, may be due to the dynamic RRPM response to loading changes. I maintain that the RRPM in dynamic response to changing load would be less for rotors that have shallower angle. This is because the "Skater" is actually pulling her arms less toward the center (Conservation of rotational inertia) than if the blades were starting off with more coning angle to start with. My logic then suggests that the Magni rotor blades would have less dynamic damping effect than more highly coned rotors because the RRPM change with loading is less - CG of each blade does not pull toward center as much since it is not initially coned so much.

This and other arguments still convince me that the dynamic damping we are seeing in the Magni is from the large HS mounted far aft - and not from rotor damping. However, I do feel that the "heavy" stick is due to the heavy rotor (inertia) - at higher than usual RRPM, and not from any "rotor damping" - two different "dynamic" components.

I'm still looking for what mechanism(s) would provide "rotor damping" and how that could explain its superb stability and rapid pitch and roll responses. I still believe that the rotor disk adjusts as quickly as the force you want to put in it to move the "heavy" rotor. Then, there seems to be no discernable lag in the airframe pitch re-aligning quickly and accurately with no over-shoot to the new flight path dictated by the rotor. Maybe its just because I fly this a lot, but I am convinced the real "secret" of the Magni is the strong dynamic damping of the very effective HS mounted far aft. And, this strong dynamic damping provides PIO resistance and extends the static AOA stability margin to strongly resist buntovers which are a static AOA instability divergence.

Thanks, Greg

 

[birdy]

I love this bloke, never misses a chance to plug his product.
Wunder how many he will sell coz of this thread. [ not that theres anythn rong with that]


This and other arguments still convince me that the dynamic damping we are seeing in the Magni is from the large HS mounted far aft
I agree 100%.


However, I do feel that the "heavy" stick is due to the heavy rotor (inertia) - at higher than usual RRPM, and not from any "rotor damping" - two different "dynamic" components.
I dissargee 100%.
But, im only a SCG, [who Greg thinks i know enuff already], so wot would i know?
Just coz i fly a machine with similar AUW, Same engine, same weight and length rotors that spin at bout the same RPM, yet is very much lighter on the stick.

I dont know why, but i gota warn the buyer to be aware, coz i have a sneakn suspision that he maybe a wee bit one eyed.

 

[C. Beaty]

This and other arguments still convince me that the dynamic damping we are seeing in the Magni is from the large HS mounted far aft
I agree 100%.


However, I do feel that the "heavy" stick is due to the heavy rotor (inertia) - at higher than usual RRPM, and not from any "rotor damping" - two different "dynamic" components.
I dissargee 100%.
But, im only a SCG, [who Greg thinks i know enuff already], so wot would i know?
Just coz i fly a machine with similar AUW, Same engine, same weight and length rotors that spin at bout the same RPM, yet is very much lighter on the stick.

I fear we have a divergence of opinions here, Birdy.

I think you’ll agree that roll rate is unaffected by horizontal tail surfaces and is limited almost entirely by rotor tilt rate.

Pitch rate can be a bit different; the horizontal tail prevents the airframe from becoming misaligned with the flight path of the rotor. Ultimately, pitching rate is limited by maximum tilt rate of the rotor.

The amount by which the rotor lags behind a control input is:

16q/γΩ* where q is the rotor tilt rate, Ω is the rotational speed of the rotor and γ is an expression of the ratio of aerodynamic to inertial force of the rotor, commonly called Lock number. You can see from the expression that the faster the rotor spins, the smaller the lag.

Stick force is a good relative measure of rotor following rate.

And of course, the more inclined the rotor is to stay in one place, the more strongly damped the airframe motion.

*Foundations of Helicopter Flight by Simon Newman, page 188.

 

[All_In]

This is a great thread! I may finally be getting it.

Thanks for taking all of your time.

You all rock!!!

 

[[email protected]]

Wow ! My head is humming now and I regret that I learned the wrong profession. The world belongs to mathematics, physics and chemistry........

I stepped off the discussion getting only 70% of the talk sorted out in my head.

But lemme tell You one thing now:

Today we had 28°C, 15 kts. from 190° on runway 16 and heavy thermals in the hills.

I opted for the Magni M22 today to fly with solo, went to the grass strip, did my prerot to 250, full throttle to 5.400rpm (didn´t need the turbo) and disengaging the break the nose was up and I was airborne. Just like this.

At 1.000 ft AGL trimmed to 95mph IAS and flew from Hungary to my place in Austria (just 30 mins) at 355 rotor-rpm. I swear, wouldn´t there have been the drift from side-winds I wouldn´t have touched the stick once at level flight and could have read the newspaper. Thermals were dampened down to nearly nuthin´ and I know the route now with all up´s and downs since 4 years at every weather-cond. The M22 flew like on a railway track.

Since our "Gyro-Master" Andreas Siebenhofer told me that this specific M22 flies just by weight-shift of the pilot I tried it: and it DID !

So coming to my place I forgot to trim back from 95mph IAS and did some "greeting-circles" for my wife who waved in the garden (at 500 ft AGL..... ME ! not my wife!). And these circles went smooth with astoundingly ease on the stick. Then, after trimming back to 60mph, stick forces were much higher.

Most force I needed when hovering against the wind (25 kts), but the M22 stood still like parked on the apron with 4600 motor-rpm.

After this I did some contour-flight over the hills and wood areas at 80mph IAS and thus trained my biceps and triceps too. Stick forces are really high but give me a "warm feeling" of security just as if the M22 tells me: "I resist You a little bit, just enough You to be shure You do the right thing" and "Maybe YOU are nervous, I am not!"

Funny thing, this gyro really speaks to me in his own language.

Well, to come to an end: after a no-feel-touchdown I was grinning from my right ear to my left ear like a weird wacko...... and took off again after getting some gas in the tank before someone else could.

SUMMARY: So whatever it is Magni has built into this gyro, whatever secrets he has, whatever complex maths and physics work together in this piece of art, I LOVE THIS GYRO. :flame:

still wacko-weird grinning Angelo

 

[C. Beaty]

Angelo, I assume you’ve flown an MT or an ELA gyro.

I am interested in your comparison of agility and stick pressure of these similarly configured machines to a Magni.

 

[chuter]

Since our "Gyro-Master" Andreas Siebenhofer told me that this specific M22 flies just by weight-shift of the pilot I tried it: and it DID !

Angelo,

Are you saying your rotor has no cyclic control? Is the head fixed?

I imagine most gyros could be controlled in a clumsy sort of way by the pilot moving his weight around, but if your rotor head moves like the rotor heads on other gyros when you move the stick then it's really using cyclic control.

What do you think?

 

[ckurz7000]

Angelo, I assume you’ve flown an MT or an ELA gyro.

I am interested in your comparison of agility and stick pressure of these similarly configured machines to a Magni.

Hi Chuck,

while waiting for Angelo to respond, I can offer a comment of my own. Having flown Magni and MT03, there's a big difference in stick force. The MT03 feels nimble and agile and the Magni flies like on rails. Yanking and banking with the Magni is a tiresome undertaking -- it just doesn't want to deviate from straight and level. On the other hand, you can't fly the MT03 hands off for such prolonged periods as the Magni. Well trimmed, the MT03 may stay on track for about half a minute or so. The Magni will stay there almost indefinitely.



-- Chris.

 

[Bcoz]

Angelo, I assume you’ve flown an MT or an ELA gyro.I am interested in your comparison of agility and stick pressure of these similarly configured machines to a Magni.

I'm not Angelo, and not an expert, but I have fly this week on a Magni m16, a ELA, and my own MTOSport.
It was a fly test on a magni, a lesson with a student on his own ELA, and differents fly on the MTO.
Undoubtedly, the Magni's stick is more hard to move than the other. It's not realistic to consider flying without trim. The more hard is to move forward/aft.
The two others are quiet the same, but my feeling is the MTO is lighter on the stick. The main difference (in my feeling) is on lateral moves who are really more easy on MTO and ELA.
Considering agility, for me there is no doubt than the MTO is more agile (it's the main reason of my choice to buy it), then the ELA, then the Magni.

Even if the global structure is the same on these three gyros, two main differences exist: the weight of rotor on Magni and ELA (composite rotors) is arround twice the weight of the rotor of MTO (extruded aluminium); and prerotator of magni (flexible cable remaining attached to the command bar).
Even on the floor, the stick of the magni is harder to move, and you move the prerotator with the rotor head.

Just my 2 cents...

 

[C. Beaty]

Thanks, Chris and Bruno. Your comments are about what I expected.

Here’s the anomaly: I imagine all 3 gyros use the same rotor airfoil, the NACA 8H12, and all 3 have about the same tail volume. The blade mass can’t be drastically different, extruded blades must have thick skins and ought to have a sufficient amount of brass at the leading edge to get near ¼ chord balance. Tail heavy rotor blades can be quite unstable even if they don’t flutter.