Tall tail

[gyroo]

Hello Matthew,Your observations are very reasonable ones to make, because the Magni (especially the M24 Orion) appear to have a mass layout involving a highly mounted engine and a low mounted pod.Remember, however, that the Magni has a reasonably light 914, has front weighted blades and has very generous stabilizing surfaces.

[gyroo]

Thanks Max for clarifying how G0023 will be used. I generally agree with your comment that if a person can"t fly a RAF properly they shouldn"t have been given a licence, but nevertheless the RAF as a type has the poorest safety record of all production machines - by a very wide margin from all the others - and people continue to be killed by them 15 years after the dynamic problems came to be understood.Our "sensitivity" in relation to 2-seat prototypes is based on the fact that G762, the 2nd production Kruza killed 2 at Mangalore in January 2012 after 305 hours in service, because of cross-tube failure.

[BrownBMB]

Mark, this is becoming an interesting topic to say the least.As a owner of a mto sport It has me wondering given the mto, calidas and cavalon seem to have the same tail design and Hs, but are of different lengths, which machine has a better/ worst thrust line?

[tonydenton]

I"m not commenting on max"s machine. but why then are rafs allowed to be sold to newbie"s. if a newbie had the money and 1 was for sale he could purchase it . this has happened.

[asra]

West Oz Flyer,The fundamentals of gyro dynamics are all out there,one just has to dig.My comment about torque mitigation is not about "P" factor, its about torque roll or "torque over" We have a recent fatality on video where this is evident.There is absolutely no torque over protection at low speeds on G0023.Re the Magni bunt-over scenario,the maths has been done on this,to "buntover" the rotors need to change direction(and loose thrust) faster than the gyro body can follow to enable the thrust(of the engine) to rotate the body and collide with the rotor.Obviously this can only happen on gyros with the thrust-line above the COG.The higher the COG offset moment arm, (torque X offset) the quicker,easier, it will happen.Everything revolves around its COG when power/thrust is applied, weather it gyro, car,space shuttle or horse and cart.All Euro gyros,apart from Magni, Have an effective HS at all speeds as they are at least some degree in the prop wash.

[gyroo]

My reply to Tony Denton -Yes Tony, I often wonder why RAFs, as a type, are still "tolerated". The answer is that essentially when flying gyroplanes each person is voluntarily assuming a level of risk associated with the activity.I notice that a non-ASRA member in Melbourne (who even has a presence on this forum) has become quite prominent on the Web over the past 12 months promoting what he calls a RAF 2999 or even a RAF 3000, claimed to be an "improved" RAF, but which I note from photographs posted on "rafgyro.com.au" that there are a number of aspects that - as Technical Manager - I would find unacceptable. Despite the carbon fibre pods being spruiked, I very strongly suspect that the design will be heavier than a stock RAF.But, as a non-ASRA member this person is free to spruik his machines on a 50% money down "build to order basis", although I strongly suspect that any unwary customer who did that would quickly bring a Trade Practices Act proceeding against him because the customer would quickly come to discover that the "RAF 2999 or 3000" is not a design acceptable to ASRA.The Board has authorised me to write to the particular individual concerned and point out that the RAF 2000 design is a gyro that is only "tolerated" on the ASRA register, and is by no means lauded by ASRA as a good gyroplane, especially considering its poor and continuing poor PIO and PPO history as a type. When I have enough time available to draft a detailed letter, I will.I have agonised over whether ASRA ought to implement the strict UK CAA limitations and restrictions on RAFs, but for the time being while we have 6 still on the register and all of the owners seem to be able to cope with them, then for the time being things will be left as they are.Apart from RAFs being very High Thrust Line, another important aspect that many people who champion RAFs skate over is the fact that RAFs usually have a 70 to 80kg heavier empty weight than any of the European 2 seat tandems or even Cavalons and Xenons.

[tonydenton]

mark, I think asra has a massive bonus as you being a "gyro naught" and on the board. I"m sure the envey of other flying bodies. your posts are obviously well written, although probably detuned from your normal "court talk voice " [ that"s a compliment ] for this lay person anyway. please keep up with the tough decision making.

[gyroo]

Hi Tony,All the work on that score has actually been done in the UK. I have attached a picture of the RAF 2000 horizontal stabilizer with end plates that is required in the UK. Even with this fitted, the RAF in the UK is STILL restricted to:1 . Basic Aircraft, not modified as defined in 2 below:- 1. Doors must be removed for flight.

[gyroo]

For BrownBNB,Howdy - MTOs come in at 7 inches High Thrust Line 2 up with full fuel, down to 5 1/2 inches with one up no fuel. That"s obviously outside the recommended "plus or minus 2 inches" but not seriously so, and the highly effective horizontal stabs of MTOs, Calidus and Cavalons dampen the phugoid extremely effectively. While it is no doubt theoretically possible to both PIO and PPO any of these machines if one deliberately tried hard enough to do so, the obvious fact that MTO"s for instance have only very rarely chopped their tail feathers off in mid air (only a couple of times so far as I can see - always fatal) demonstrates that their overall configuration is reasonably satisfactory from a dynamic perspective.I don"t have a set of Calidus hang and tilt-back photos to plot, but in my pile of things to do I do have a Cavalon set. When I get the time I"ll plot the Thrustline / CofG - maybe it"ll be the same as an MTO - I dunno.If all the members want to contribute $1000 bucks each we"ll get a wind tunnel built and quarter scale models of all the various factory-built machines built and do comparative testing. How"s about it, gang???Mark Regan

[aussie_paul]

Mark, I did my damdest to help rafgyro as did Echo who told him he was lucky to have me just up the road with all my RAF 2000 experience. I have wiped my hands of him as he will not take one piece of advice. Aussie Paul.

[Disco]

We"ll I clicked the link on his website which said " is it safe?" And it said hell yes.

[gyroo]

For Tony,I appreciate your compliments and have only fully understood what you were musing about with your last reply - namely, could ASRA devise some sort of "R & D" process to demonstrate configurations that are an imminent PPO hazard and then to see whether such a configuration can be tamed by re-arranging the masses within the airframe as well as by experimenting with stabilzers.It"s probably feasible for such testing to be done remotely on half scale machines, where a few would be made and sacrificed destructively to the God of PPO, but it is unthinkable for a manned gyro to be involved in such testing. The Brits backed away real quick from taking manned "jab testing" (sudden pitch deflections of the stick) in a Montgomerie Merlin too far when troublesome short-period oscillations started up. Manned testing is just too dangerous.Smaller scale testing can provide useful information. I have a 2 metre diameter model helicopter rotor set into a fixed pitch hub bar. One Sunday afternoon a few years back I drove to a very large vacant factory car park and clamped the rotor to the front bumper on a 1 1/2 metre vertical post, and I jury-rigged some wooden dowels to be able to pitch it back and forward over about 15 degrees. It was dead easy to hand start and while driving in wide circles quite slowly the rotor spun up very powerfully and kept spinning powerfully right up to maybe a couple of degrees tiltback. Pushing a little bit further forward almost to the point where the disk looked pretty much horizontal the autorotation suddenly gave up and the blades flapped markedly as they slowed down rapidly. This was all very interesting and was a fun few hours, but how scientifically valid it all was is a different question, because that little rotor setup was fixed to my bumper, whereas with a gyro in flight the gyro rotor is attached to the gyro frame which is "in space" and not attached to the ground.The moral of the story is that (1) I agree that testing and experimentation is always worthwhile, but (2) only if no lives are put at risk.Cheers again,Mark Regan

[gyroo]

Thanks Paul -I"ll keep your comments in mind.

[mad max]

Just been wondering around my yard with a measuring tape. My Rosco clone, been flying it and another one the same for 20 yrs. Same thrust line as G0023. Virtually no hor. stabiliser. Measured another machine made by a well known manufacturer in the south. Higher thrust line than G0023 with higher engine. Gearbox facing down. 180 HP Subaru. All craft fly well (In the right hands)

[gyroo]

Thanks Max,Sounds like you"re talking about a Peter Green. It"s quite counter-intuitive but a higher mounted engine with a C Box facing down actually improves the Thrust-line / CofG situation rather than worsens it. Straight through re-drives using epicyclic gearing neither improve or deteriorate the Thrust-line