Double amputee Solo in RAF 2000

[mad max]

All gyro pilots should be trained to instinctively pull the throttle back during turbulent conditions and keep a sharp eye on the ASI. The conditions generally drive you up anyway due to high airspeeds. I often allow the craft to face a new direction if it wants to for a while untill things settle down again. Going through inland whirl winds is frightening at first but can be fun once you develope the skills to survive and loose some of the fear. (I must confess if I have a passenger at the time I refuse to talk while concentrating).

[gyroo]

Thanks T-Bird,Much of what we"ve all been discussing back and forth can perhaps be lumped under "Handling Qualities" which is a much more informative label than "dynamic stability". The fuselage or pod of every rotorcraft to a greater or lesser extent will behave like a pendulum under the rotor (those with good horizontal stabilizers are much less subject to pitch "excursions" as they are called). The control stick is almost always anchored to the floor of the pod and human brains seem hardwired to instinctively and subconsciously want to keep the stick steady with reference to its surroundings in the pod if the pilot at any given moment is not intentionally maneuvering. Gyros are more prone to PIO than many types of aircraft because most are very "short coupled" - they are often short and stubby and don"t have a nice long fuselage with nice big tail surfaces a long ways back from the CofG like planes have.The subconscious tendency of a human to try to keep a stick steady within a cockpit is also one of the main ingredients of PIO, where with the pod pitching back and forth a wise and experienced pilot will realise "I don"t need to try to damp out or chase this", whereas an inexperienced pilot will fall into the trap of doing control stick pitch movements that he or she thinks will dampen down the pendular pitching. In the vast majority of cases even the most ham-fisted newbie won"t actually do much harm and things will settle down within a number of seconds until the next upset or turbulence hits. This is all part of the post-pilot-certificate self-learning process that we all know so well: learning to leave it alone, to not make things worse. Very occasionally, however, an unfortunate newbie"s control stick movements will exacerbate the pod-pitching tendency, or in other words their stick inputs will be so badly out of phase with the pod pitching that their inputs actually worsen the pitching instead of dampening it.The fact that many gyros are completely open-frame without a pod shouldn"t be overlooked. In these configurations it is absolutely essential for a newbie to have a visual airframe reference as far out in front of him or her as is possible. The ideal situation is a radio aerial on the very front of the keel with the top of the aerial level with the horizon from the pilot"s viewpoint when on the ground. In flight all the newbie needs to then do is watch where the top of the aerial is with reference to the horizon. If an open-frame gyro hasn"t got any such visual airframe reference for a newbie there"s a potential PIO disaster lurking just around the corner.History (in the UK and here) seems to show that very occasionally inexperienced pilots caught in extreme turbulence tend to try to "plow through" no matter what and in-effect wrestle with the controls chasing and trying to counter the pitching and rolling. Rolling isn"t too much of a problem, whereas pitching is. In extreme turbulence with little experience, things can get so bad with the pitching that the g-loading on the rotor is substantially unloaded and the mast-pitching-or-rolling moment able to be produced by the rotor vanishes, but the ability of the rotor to wildly flap or even flail does not (called unconstrained flapping) because the rotor is still at a high rpm.In these seconds, speaking from a dynamic point of view, we come to a fork in the road. Fork in the Road 1If the machine is CLT or near CLT, such as a Newo, there will be no tendency for the pod to bunt over because the thrust line is more or less in line with the gyro CofG. Nevertheless, if the pilot is absolutely determined to plow through "no matter what", then the rotor is likely to be encountering transient episodes of reduced or even severely reduced-g and in this circumstance the inexperienced pilot will be finding that no matter what he or she does with the stick, the gyro doesn"t seem to be responding (because any pitch-tilting-moment being generated by the unloaded rotor is reduced in reduced-g). The pilot then unconsciously over-controls or puts in harsher or harsher stick inputs. Now, despite the fact that the unloaded rotor can"t tilt the mast, the rotor is still spinning at near-full flight rpm and the tilting head is being swept through extreme angles. The rotor will try to follow the harshly tilting spindle and that"s where the catastrophic flapping - or unconstrained flapping - comes in, in exceptional circumstances being violent enough that within one or two rotor revolutions the teeter stops have well and truly been struck and the head partially wrenched off the mast and one or other of the blades will sweep down so violently that a blade scythes through the pod. This has happened in Australia in both helicopters and gyros. This is what happened with the Newo customer first-pick-up-flight fatality you mentioned - the pilot had previously held a fixed wing licence and inexplicably just "firewalled" it determined to plow through extreme turbulence.I stress that for such a catastrophe to occur one must have the near-lethal combination of heavy turbulence, a gyro being flown at very high speed, and a pilot inexperienced in gyros absolutely determined to "plow through no matter what" and who is wrestling and chasing the controls and overcontrolling.Fork in the Road 2If an identical set of circumstances arises with a gyro that is significantly High Thrust Line (HTL), then the catastrophe described above will happen much earlier in the event and more assuredly. This is because the High Thrust Line WILL pivot or pitch or bunt the gyro forward around the gyro"s CofG UN-COMMANDED even before the situation with the reduced-g rotor has got to the point where there is unconstrained flapping. A common and telltale characteristic of PPO in fatal accidents is evidence of multiple and progressively worsening rotor strikes on the vertical stabilizer and/or rudder. Frequently, in these PPO accidents the VS and rudder are located away from the main wreckage indicating the rotor strikes detached and flung those surfaces away from the plummeting gyro.What has happened with the HTL gyro here is that essentially although the rotor has not yet reached the "point of no return" (or in other words it"s not yet flapping catastrophically), the gyro frame itself is now pitching forward uncommanded because the thrust line is so much higher than the airframe CofG. The final icing on the cake in this particular recipe is that as the pilot senses the un-commanded bunt or nose-down pitching, he or she will naturally pull the stick back. However, it is extremely likely that the bunt-over will have already put the rotor into a severely reduced-g situation and wrenching the stick back hard won"t save things - in fact it"s likely to induce the unconstrained flapping spoken of in the paragraphs above, this time induced in a slightly different way. Another way of imagining this is that as the gyro bunts over, the frame is taking the rotor over with it. The pilot, however, pulls harshly back on the stick but that may either stop the rotor bunting further or may cause it to flap back harshly. In any event the tail has come up into contact with the rotor so it"s all over anyway.The end result will be pretty much the same - the rotor is likely to be pitching back harshly as unconstrained flapping starts up, but in any event the gyro frame and tail are bunting over and the tail comes up into the rotor arc that much quicker.You will now appreciate that it is often subtle differences in the wreckage that enable the break-up sequence to be determined and for whether a PPO has occurred.Conclusions From the analysis above one can see that it is possible to turn any gyro into pieces of aluminium confetti if one really, really tries hard enough to destroy one in flight. The same can be said for any flying machine, or indeed even any car if a driver deliberately and suicidally has a sudden impulse to veer off the road and aim for a tree.The hypothesis with HTL gyros is, bac

ked up by the University of Glasgow research, that in the harrowing conditions outlined above the HTL gyro is very much more likely to PPO to destruction before unconstrained rotor flapping starts.The more HTL a gyro is, the more readily it will enter un-commanded PPO.Cheers,Mark R

[t-bird]

Thanks Mark.It makes sense.

[tonydenton]

your wearing them down mark.

[gyroo]

Howdy again T-Bird,Murray"s point is that the unique RAF mast mounted stabilator is actually a horizontal stabilizer for the torque tube or torque bar. It is naturally heavily airspeed dependent. Its purpose is to keep the torque tube or torque bar orientated at a pre-selected angle to the oncoming airflow, and therefore the rotor tip path plane will also be stabilized because the spindle is rigidly attached perpendicular to the torque bar. It is true that RAFs with the stabilator can be flown for prolonged periods hands-off-stick. But, what Murray is talking about is that in this hands-off situation the stick will pitch forward or aft of its own accord if the pod is experiencing a bit of pendular effect in turbulence. And, in such turbulence its conceptually much better to leave the stick alone because the stabilator will be free to do its work without interference.If the pilot of this stabilator-fitted RAF, who is sitting in a fixed position in a pod experiencing a bit of pendular oscillation, grabs the stick and prevents it from "doing its own thing", then - in effect - the pilot and the stabilator are fighting against one another. That"s what Murray is commenting about.There"s nothing wrong with a bit of mechanical stability augmentation - look at the Hiller control rotor in Hiller 12s, or the Bell stabilizer bars on Bell 47s or UH-1B"s, C"s, D"s. E"s or H"s. The point is that modern gyros simply don"t need mechanical stability augmentation - except for the RAF!Mark R

[birdy]

And about the thread be,n hijacked off ol mates solo, well, you can only blame the thread starter for that.

[t-bird]

Hi BirdyI absolutely agree with you and I never said it is a stable machine. Maybe you should consider some baby powder before a flight to help with the itch.Murray Baker I am not sure what you mean by your comment on the stick. You previously said that the oscillation was produced by the Raf and not pilot hence me posting the video of them flying hands off.I don"t want to refer to specific accidents but say for instance my accident were similar and the pilot have over controlled. Why whould it happen ?

[asra]

Mmmmm, just a couple of things to clear up here.As I previously stated,I have flown a RAF hands off, for half an hour or more.It had the "Stabulator". There is NO WAY I would have done that with the stick solidly fixed.I don"t think anyone would be that silly.As soon as you fix the stick so it can"t move AT ALL, the "Stabulator" becomes redundant.Get RAF South Africa to post a video of that and only then will I be impressed.T-Bird I think the fatality you may be thinking of was the "Newo" gyro that crashed on its delivery run to Caboolture?I was the first responder to that crash site and it wasn"t PPO, it was over controlling in bad weather to the extent of hitting the teeter stops, resulting in the rotor slicing through the cabin at 90* from its normal angle.Like mast bumping in a helicopter,fatal.That"s something that can happen in LTL, CLT or HTL gyro"s and has happened twice since.

[Disco]

An interesting test would be if the South African figures were available for other types.

[birdy]

T-bird, the difference between an inherantly stable machine and one that is stabilised by a over trained pilot is, the inherantly stable machine is stable all the time, and is not prone to brain farts, ego, tiredness, poor judgement, bad visability, flyn outside its envolope, itchy balls or anythn else that could distract its attention.Its stable, no matter wut.My 84 modle tojo will drive strate hands off, down an airstrip.But its not stable.One bump, bit of drag one side, blowout or anythn that deviates it from the strate line, and like an RAF, it wont self correct.Hours accumilated mean nuthn without every vairiable Included.I could drive the tojo up n down the strip all day hands off, till i hada blowout.

[t-bird]

Hi Mark You said that Murray is talking about

[gyroo]

Yeah, Disco, I agree with what you"ve just said. From what T-Bird has informed us about, namely the extensive and rigorous training and ongoing supervision that South African gyro pilots and gyros are subject to, then one would expect a near zero fatality rate because all the pilots are so clued up that they can pretty well handle anything. 20,000 divide by 46 = an average of 434 hours per South African RAF.Maybe if the US, the UK and Australia had similar rigorous training and supervision regimes, then serious accident rates would similarly shrink.The high-standard-of-training point that T-Bird has been continually emphasizing is very worthy of us all sitting up and taking notice of.This meandering thread has been valuable on that score alone.Mark R

[Disco]

Maybe tbird"s point is that if great training has been able to get even the dodgy old raf to obtain a great record, imagine what would be obtainable with that sort of training and a stable gyro.

[gyroo]

Hi T-Bird,I"m still slightly troubled by the way you are approaching your postings. You, as an experienced pilot, will full well know that "flying into a 35 knot wind" (which in the videos is clearly in a steady state) will result in any powered flying machine sitting as solid as a rock but with a much-reduced ground speed. Obviously, what these guys are doing is they"ve pointed their RAF into the prevailing wind and are enjoying the hover-like illusion that dramatically reduced ground speed gives you. We"ve all done that on days with steady strong winds - its great fun.But I stress again that these enjoyable videos can"t be used to infer that RAFs have satisfactory or acceptable dynamic stability. That"s what I"m finding to be slightly irritating - in this case by having purposely selected these videos it seems you"re trying to infer that RAFs aren"t nearly as bad as some of us on this forum are making out. We are all, of course absolutely entitled to our own opinions. Constructive debate is often a great way of drilling down into the heart of any contentious matter.What Murray and me are talking about is consider the situation where an inexperienced pilot is flying "a stock RAF" in blustery and turbulent conditions, is not manipulating the control stick smoothly, is having trouble with directional control, is applying and reducing throttle rather abruptly, is maneuvering, and is not attuned to the pendular response of the gyro to maneuvering in the blustery conditions. Even I will admit that such an inexperienced pilot in the circumstances described will still - in most cases - eventually land safely but exhausted after having struggled with the machine during a very unpleasant flight. But, very occasionally, an instance will occur where the inexperienced pilot in a RAF will not land safely because a combination of the circumstances listed above will trigger a PIO that exacerbates to PPO and a fatality. If a gyro design has good dynamic stability, which I suggest the RAF has not, then in these same conditions or circumstances the flight will still be very unpleasant but there won"t be an attendant fatality risk.Cheers,Mark R

[t-bird]

Hi MarkAs said before Raf = PIO. I am not trying to convince anyone that it is not.As for calm flying conditions wind was blowing 35 knots in the one video.Here is another video just for funhttp://m.youtube.com/watch?v=MQDHH6qdbkw&desktop_uri=%2Fwatch%3Fv%3DMQD HH6qdbkw