MT03 tail-crop

[EI-GYRO]

AAIB report;

http://www.aaib.gov.uk/cms_resources.cfm?file=/Rotorsport%20UK%20MTOSport,%20G-CGEW%2010-11.pdf

Is this what the Aussies were concerned about?

[PTKay]

An issue mentioned many times, never clearly admitted
by AutoGyro GmbH.

The discrepancy in the manual is interesting, to say the least.

[Texasautogyro]

This situation does not surprise me. In an MTO you never want to have the stick full back under 120 rotor rpm. The blade is hollow non weighted tips it produces flap even at 150 rpm if you hit a bump in the run way. Normally I do not taxi with it in motion its not needed with the MTO. I train how to do this for students because its needed in other models. The MTO also has no tail wheel so you do not land with such a high nose normally. You do need to be aligned with the runway. No tail wheel to fix it if someone crabs.

Texas Auto Gyro MTO Sport - YouTube (http://www.youtube.com/watch?v=_DvBjinwfXM&feature=colike)

I show this in the previously posted video. We do full runway into the wind rotor work then down wind. Look close the rotor gets close and we are between 150 and 200 rpm

[i3 roberto]

Yes: the same problem with hela too

[Gyro_Kai]

one of the first things you learn: stick forward, regardless, untill you are above 100 rrpm.

Kai.

[rfsolutions]

Wouldn't taxing a gyro with hollow blades (any blades actually) without rotation increase stress on the blades? Especially if the gyro has semi rigid suspension and the taxiways and runway are anything but smooth?

[Texasautogyro]

The MTO blades are very light. I learned to fly in Costa Rica and we never taxi with them in rotation. Some of these MTO's have 800 hrs on them with no problem. I do not know if it stresses them as you say or not. When I fly an Air Command or RAF its hard to controle with out rotation but they have heavy blades. I know that the heavy blades bounce alot and can hit things when not loaded.

[rfsolutions]

I learned to fly in an RAF. McCullouch J2 POH and I believe Air & Space 18-A all require taxiing with blades in rotation when taxiing on unimproved (grass & dirt) surfaces and they have both have suspension. The gyroscopic action aids stability while taxiing as well as reducing stress on the blades & rotor system. Rotor blade management during non-flight movement is all part of learning to fly a gyro. If you're flying a gyro with semi rigid suspension and not rotating the blades when taxiing on anything but ideal surfaces you're stressing the rotor system. Especially if the blades are hollow extrusions light or not. I was taught to fly and got my rating from a old school knowledgeable instructor. Hollow extruded rotor blades need all the help they can get to reach the TBO of an airframe. I'll bet there's not a set of hollow extruded blades flying with more than 2000 hours on them. Taxi them on unimproved surfaces without rotating them and I bet they won't make 1000 hours.

[Vance]

Wouldn't taxing a gyro with hollow blades (any blades actually) without rotation increase stress on the blades? Especially if the gyro has semi rigid suspension and the taxiways and runway are anything but smooth?

Hello Marv,

Are you advising me to taxi my gyroplane with the blades spinning?

Would solid blades be better than hollow blades?

In your opinion does the MTO have semi rigid suspension?

Thank you, Vance

[JAL]

Rotating when taxing over rough ground is to protect the hub bar more than the blades, especially a solid hub bar.

The MTO3 has strap type hub bar which I think would transmit a lot of the stress back into the blades as the main flex point in this set up would actually be the root of the blade and not the hub bar. Where the blades are fixed to a solid hub bar then it is more likely the majority of the bending forces would be carried within the hub bar.

The MTO3 set up would also have some additional stress in the blades as there will be differential movement between the top and bottom strap (the blades are sandwiched in between) this might explain how there was deformation around the bolt holes on the last blade AD came about, more so than low g maneuvers.

Autogyro recommend that you don't taxi with blades rotating and they have set up the pre-rotator so that it only be engaged with the stick full forward. It would have been better with the set up they have chosen to recommend to taxi with blades turning over rough ground and have it so you can keep >120 rpm by using engaging the pre-rotator (with the rotor disk back) when you need it to keep the revs up so that you don't have to taxi too fast to keep the blades spinning, especially downwind when back tracking on a rough strip where the faster you go the harder the bumps so you kind of get into a bit of a lose - lose scenario.


Also there was requirement here in Australia that the rotors must clear both the prop and tail, which one model of MTO3 did not do and new rotor heads where required and those that didn't comply were swapped out. This indicates that Autogyro does have a fix for those who want the clearance, those who don't can keep it as it is because I assume that means they can get more back stick in the flare. But in doing so would have to be mindful of the added risk of taxing with blades rotating or only fly from smooth runways and taxi ways so they don't need to taxi with rotors spinning or accept that the blades are going to last 800 hours.

It also recommend here in Australia to taxi with blades rotating, especially over rough ground. There is the added bonus of taxing with blades rotating is that you don't need to stop and pre-rotate at the end of the runway, you can just start straight into the take off run slowly and the blades come up to flying speed pretty quickly saving the wear and tear on you pre-rotater which you only have to use when take-off distance is restricted or just get the blades moving and save a lot of stress on it.

It is also a lot more fun, but I would recommend spending some time practicing blade sailing by taxing up and down the runway slowly and getting the feel of how fast your blades spin up to make sure you avoid blade flap. This probably sounds weird to those who fly the single seaters without much of a pre-rotator or not one at all but with the MTO3 at least (but I am sure most of the training on the new generation gyros) you are not taught to taxi with blades spinning or even spin them up slowly. You are taught to taxi to the takeoff point engage the pre-rotator wait to you get > 200 rrpm and then take-off and miss the whole getting the blades to spin up from low rrpms.


Jordan

[Texasautogyro]

I have seen 3 Mto hub setups one had I think 8 bolts per blade mine has 6 and then they made the rotor head slightly higher like Jordan said. I was in discussion with people from Auto Gyro about this and they said it also helps with vibration harmonic as well.

[Doug Riley]

I see gyro pilots taxi with their blades stopped a great deal. At some flyins, this practice is required by the field rules. It's tolerable on smooth pavement.

My local airports are grass, however. I always prespin to a bit above engine-idle RPM before taxiing. I would cringe to think of the stress at the center of the rotor as the blades bend with the bumps.

Some gyro designers push their luck with tail-to-rotor (or prop-to-rotor) clearance. My original Air Command had zero prop-rotor clearance with the rotor flapped back, the stick full aft and a normal droop in the blades. The composite blades and plastic prop would "chirp" when they made light contact at the onset of flap.

[rfsolutions]

Vance,

Blade rotation prior to take off is really dependent on field conditions as Doug and others have pointed out. When the area is crowded with bystanders like fly ins it's prudent to stop rotation before the area where people could be injured.

On smooth surfaces like asphalt and concrete it's not that big of a deal but on grass and other rough fields it's simply abusive to the rotor system. You have a long moment arm putting stress someplace. Whenever practical it is always advisable to move the gyro with the blades rotating, especially if I were flying hollow extruded blades. If you question the physics about it contact a blade manufacturer.

[Vance]

Thank you Marv,

Most of my flying is off of paved airports or a dry lake and I have not been taxiing with the blades spinning. My blades have about 850 hours on them and seem to be holding up well. I replaced the rotor head bearings at the same time as the blades and inspect them each year during my annual condition inspection. The original bearings had less than 200 hours on them when they started spitting metal shavings out through the seals.

I asked about solid blades because of you mentioning hollow extruded blades as though there was a solid extruded blade for gyroplanes.

I have never seen solid aluminum blades, extruded or otherwise.

I have not seen any solid gyroplane blades except made from wood.

Thank you, Vance

[birdy]

Is this what the Aussies were concerned about?
Id never buy/fly any gyro that was built by a non flyer.
Cant believe theres still machines built with no rotor/tail clearance and no tail wheel. WTF!. I dout i could land on the mains first, and still be on me 'G' spot.

Oh, and iv never tookn off from a surface that would allow taxin without the rotors spin'n.

[Greg Mitchell]

'Tookn'......LOL!
That's some serious word creation there Birdy

[jeff b]

All MTO's coming into Australia have the Aussie version head block. This gives the required clearance between the tail & rotor blades as required by ASRA. When mine was changed from the original, I hardly noticed much difference. Wonder why the Factory didn't just change the spec for all new MTO's built to have the same as the Oz version?

Jeff.

[ferranrosello]

I think that there is no reason to taxi with spinning rotors other that the pilot’s comfort. Taxiing with the rotor spinning implies back stick, and specially in rough terrain is possible the rotor blades hitting the tail fin in spite of having a good clearance with the rotor stopped.

On the other hand, taxiing with spinning rotors is dangerous for people and other aircrafts in the parking areas, and safety comes first. So, is a good rule to establish a prerotation point and rotor stopping point in the airfields, in order to avoid accidents.

I understand perfectly the need to taxi with spinning rotors in some gyros with not rotor brake. But modern gyros have good rotor brakes and taxiing with stopped and aligned rotor is comfortable. These gyros are much more difficult to get prerotated by hand that the old ones, so it is very easy hitting the tail and the propeller in this kind of prerotations.

Finally, I don't like some approaches and landings I’ve seen in the video. All gyros need to be landed with a sane nose up attitude, and hold this attitude until the pilots runs out of rear stick. So gyros should have a rear wheel or some kind of tail protection. Gyros are not helicopters. In a helicopter the pilot needs to protect the tail rotor from hitting the ground in the landings... except in real forced autorotating landings. In gyros there is no need and lowering the nose only will carry problems.

Shallow approaches are dangerous and push the stick forward in a landing, letting the nose wheel touching the ground with speed is a capital mistake flying gyros... In my opinion this is the major cause of minor accidents in gyrocopters.
Two things: avoid taxiing with spinning rotor and land always as slow as possible. I know that the first rule is against old times golden rules, but flight safety comes first.
Ferran

[Gyro_Kai]

The taxiing with spinning rotors was considered good practice in Germany, to clear the run-way when you have landed short of the taxi-way and someone is behind you. As it turned out, a lot of roll-over accidents were caused by this, because people did rapid turns with RRPM 150. Now it is not taught any more, let the other airplane go around.

Kai.

[SamL]

A design which enables the rotor blades to contact the tail and or prop is unacceptable, and dangerous. It shows poor operational design considerations.
In Australia our ASRA 2 seat Construction Requirements for Compliant Gyroplanes state the following. (NOTE "including blade flap" at the end)

D100 Rotor Blade Clearance
There must be enough clearance between the rotor blades and other parts of the structure to prevent the blades from striking the propeller or any part of the structure or passing through any area likely to cause injury to occupants during any operating condition (including blade flap).

The way I test for this is to
1) unlock stick, apply full back stick.
2) pull blade down until teeter stop is hit.
3) then pull blade down applying reasonable force using only 1 hand.
4) Should still have at least 100mm clearance there after.
5) also complete same check for both right and left of gyro looking for adequate blade to ground clearance.

Here in OZ we teach all students to spin up blades during taxiing. This enables them to safely spin up and taxi during future rough Field operations. We also teach takeoffs using a minimal pre-rotation speed of only 50-60 RPM with full back stick (including hand starting). They are also taught to identify the oncome of blade flap, its causes, and fixes.
All this make for a better informed, better prepared and safer all round Gyro pilot regardless of the machine he or she flys.

Safe Flying
Regards SamL........:)

GT Gyroplanes KRUZA 2 "RCA 's new Trainer" - YouTube (http://www.youtube.com/watch?v=2c3rqBkxiO4&feature=channel_video_title) RCA's GT Gyroplane KRUZA Flight Cam - YouTube (http://www.youtube.com/watch?v=A4l8NLFj52M&feature=channel_video_title)

[Doug Riley]

Allowing rotor blades to flex heavily while travelling over bumpy ground, with no centrifugal effect to stabilize and stiffen them, can compromise safety.

I believe cracks at the roots of the blades are rather less than safe.

The blades obviously should not be turning at 150 RPM during ground maneuvers, but that does not mean that 0 RPM is better. 75 RPM or so is good practice if the ground surface is uneven. Use the stick to prevent the wind from getting under the rotor disk.

[SamL]

Allowing rotor blades to flex heavily while travelling over bumpy ground, with no centrifugal effect to stabilize and stiffen them, can compromise safety.

I believe cracks at the roots of the blades are rather less than safe.

The blades obviously should not be turning at 150 RPM during ground maneuvers, but that does not mean that 0 RPM is better. 75 RPM or so is good practice if the ground surface is uneven. Use the stick to prevent the wind from getting under the rotor disk.

2 right Doug, Rotor management is fairly simple when you know how.
Cheers SamL.....

[ferranrosello]

Doug, I agree that having cracks in any place of the rotor and blades is not safe. What I can’t agree so easily is the relationship between taxing with spinning rotors and not having that cracks. I think that rotating conditions give much more stresses to the rotor that just taxiing (more than one ton). Of course, this is stiffing the blade, but I think that the bending movement that is suffering the rotor when stopping in gusting conditions is much heavier that those related to taxiing.

And Saml, management of the rotor in the ground is very simple: full forward and centred stick and nothing will happen. But I’ve listened too many times that every autogiro pilot should be able to hand start his rotor. And every time I’ve seen a very experienced gyro pilot to do so he has hit the propeller with the blades... Once I had a prerotator failure when the rotor rpm were 100 rpm in an ELA, and I still was able to terminate the rotor prerotation taxiing (I had a long runway). But I think that this kind of prerotations (especially if you start the ground taxi below 50 rpm) in big rotors are too prone to end with the rotor hitting the tail. So, I’m not teaching this procedure to my student pilots.

Ferran

[birdy]

Of course, this is stiffing the blade, but I think that the bending movement that is suffering the rotor when stopping in gusting conditions is much heavier that those related to taxiing.
The rotor flapn at low rpms in windy conditions is no way near as stressfull on a hub bar as bouncing BOTH blades wen taxing without them spin'n.
Wen they press the stops at low rpm, its only one blade root at a time thats under a little stress. Wen they bounce wen stationary, both blades are applying bending force to the bar, so its twice as much stress.
Besides, its very simple to wind blades up/down, even in 50 kt winds, without hardly ever touchn the stoppers, if done rite.

And every time I’ve seen a very experienced gyro pilot to do so he has hit the propeller with the blades...
Obviously this 'very experianced' pilot didnt learn much while gain'n this experiance.

Once I had a prerotator failure when the rotor rpm were 100 rpm in an ELA, and I still was able to terminate the rotor prerotation taxiing
Why terminate??
100rrpm is plenty of speed to get them up to flyn speed without a prespinner.
Oh, sorry, i forgot, your machine will chop its ass off if you tryed that. :)

[SamL]

And Saml, management of the rotor in the ground is very simple: full forward and centred stick and nothing will happen. But I’ve listened too many times that every autogiro pilot should be able to hand start his rotor. And every time I’ve seen a very experienced gyro pilot to do so he has hit the propeller with the blades... Once I had a prerotator failure when the rotor rpm were 100 rpm in an ELA, and I still was able to terminate the rotor prerotation taxiing (I had a long runway). But I think that this kind of prerotations (especially if you start the ground taxi below 50 rpm) in big rotors are too prone to end with the rotor hitting the tail. So, I’m not teaching this procedure to my student pilots.

Ferran

Hand spinning the blades in an enclosed machine is almost impossible, but I did it once to show and prove a point. My machine flys a set of 29 foot tapperd glass blades with 9 inch roots and 8 inch tips. They are made here in OZ and are one of the heaviest blades around. Yet every student of mine has learnt to bring them up from 50 RPM and fly.
Once again, a design which enables the rotor blades to contact the tail and or prop is totally unacceptable, and dangerous. Such a design shows poor operational design considerations.

Regards SamL..........

[Mark E]

VERY nice looking machine there SamL!!:first:

[Vance]

[QUOTE=SamL;445985]A design which enables the rotor blades to contact the tail and or prop is unacceptable, and dangerous. It shows poor operational design considerations.
In Australia our ASRA 2 seat Construction Requirements for Compliant Gyroplanes state the following. (NOTE "including blade flap" at the end)

D100 Rotor Blade Clearance
There must be enough clearance between the rotor blades and other parts of the structure to prevent the blades from striking the propeller or any part of the structure or passing through any area likely to cause injury to occupants during any operating condition (including blade flap).

The way I test for this is to
1) unlock stick, apply full back stick.
2) pull blade down until teeter stop is hit.
3) then pull blade down applying reasonable force using only 1 hand.
4) Should still have at least 100mm clearance there after.
5) also complete same check for both right and left of gyro looking for adequate blade to ground clearance.

Here in OZ we teach all students to spin up blades during taxiing. This enables them to safely spin up and taxi during future rough Field operations. We also teach takeoffs using a minimal pre-rotation speed of only 50-60 RPM with full back stick (including hand starting). They are also taught to identify the oncome of blade flap, its causes, and fixes.
All this make for a better informed, better prepared and safer all round Gyro pilot regardless of the machine he or she flys.

Safe Flying
Regards SamL........:)

QUOTE]

Hello Sam,

To the best of my knowledge I have not flown a gyroplane that would pass the test as you describe it.

Early on flying the two seat tandem I fly I hit the tail with the blades when I was trying to hurry the takeoff with a failed pre-rotator. It did not do much damage and I have not hit it since.

Based on what I have learned the gyroplane I am building would also not pass the test as you describe it.

I feel the advantages of a tall vertical stabilizer/rudder and light flexible blades out weighs the need to keep any possible contact from occurring between the rotor and the vertical stabilizer even during flapping.

I like my light flexible blades and tall vertical stabilizer/rudder and I am thankful that we do not have such a regulation limiting design freedom in the USA.

How many Kruzas do you have flying?

Thank you, Vance

[ferranrosello]

Bird, I meant that I got full rpm taxiing and then took off. I terminate using the prerotator…
I appreciate your comment on the rotor bouncing, but I think that the forces involved when the rotor is spinning are much harder than with static rotors, in spite that the bounce may be lighter. Are you sure that is much worse the static bounce that the spinning one.
Salm, I’m sure that my gyro is not going to pass this test. And I think that, Magnis and MTO’s are not going to pass this test. Or well maybe yes… because the reasonable amount of hand pressure …. Could be no pressure?
What about these gyros? If you put the stops in a higher position then you can feel the blades hitting the stops in rough air. If you put lower vertical fines or place them closer to the autogiro’s main body then you will not have enough rudder control without power…
The stability and control qualities of these machines are superb. And having such a big clearance is not going to save you if you have a bad flapping situation in flight.
Trying to start up a rotor by hand has no sense when you have a prerotator capable to spin up your rotor very closed to take off rpm. In fact is forbidden in Ela’s flight manual and so Ela’s have not big clearances like other gyros.
Ferràn

[SamL]

Vance, GTG has built 7 machines thus far.

http://www.gtgyroplanes.com.au/

Ferran, the fix is very simple and will add stability as well as raising your CofG. All MTO and ELA need to do is raise the head by extending the mast. This may also help better absorb any rotor vibrations.
Cheers SamL.........

[birdy]

but I think that the forces involved when the rotor is spinning are much harder than with static rotors,
The only force ona a spin'n rotor is outwards, and hub bar/blade roots are designed to handle this. They are NOT designed to take virtical loadfs other than their static weight.

Are you sure that is much worse the static bounce that the spinning one.
Its logical Ferran.
If they have a virtical force applied wen they are under centriphical influence, they will hardly feel it. No centriphical force, no counter force. Pretty simple.