Russ Posted January 30, 2021 Posted January 30, 2021 A little off topic, but....Yet to find an instructor that will teach full auto rotations to full stop on ground in a helo. Sometimes i wonder if they can actually do it themselves. Most power up 100....200ft AGL, if not higher.
spacesailor Posted January 30, 2021 Posted January 30, 2021 SCARY ,. You need an Autogyro guy, Like they had at EasternCreek, so many years ago !. spacesailor
old man emu Posted January 30, 2021 Posted January 30, 2021 26 minutes ago, Russ said: Yet to find an instructor that will teach full auto rotations to full stop on ground in a helo. Being serious here. Is that because the full stop on ground is actually the result of the descent of the helicopter ending when it contacts the ground? And that contact is properly called a collision and one result of a collision is deformation of the aircraft in some way or another? What is the rate of descent of Russ' helicopter in an autorotation? I expect that it would be less than the the rate due simply to gravity because of the Lift produced by the rotor. If an object fell from 100 ft to the ground, ignoring wind resistance, it would reach the ground travelling at a speed of 24.5 m/sec, or 88 kph. v^2 = u^2 + 2as where: v = final velocity m/sec u = initial velocity m/sec a = acceleration due to gravity = 9.81 m/sec^2 s = distance metres (100 feet = 30.5 metres) v^2 = 0 + 2 x 9.81 x 30.5 = 598.41 v= Sqrt(598.41) = 24.5 m/sec = 24.5/27.7 kph = 88 kph 1
spacesailor Posted January 30, 2021 Posted January 30, 2021 But with Autorotation, the lift can be a Lifesaver !. The Gyro-Glider l had my tif in, always had a "DeadStick " landing. So there must be one or two still flying. spacesailor
waraton Posted January 30, 2021 Posted January 30, 2021 Almost every landing in my gyro is power off. Drops like a rock with no power, forward airspeed is the key. Like everything, practice.
Russ Posted January 30, 2021 Posted January 30, 2021 Auto rotations are a requirement of training, but many, if not all insurance co’s will not cover helo if damages are auto related. So training is up to the last bit before touchdown, its the touchdown bit that student really needs to master, especially when you have low inertia blades. Air speed with exact flare, then settle. Gets the pucker valve working. 1
old man emu Posted January 30, 2021 Posted January 30, 2021 Isn't it strange? You an do deadstick landings in a fixed-wing plane as part of training, but you can't do deadstick in rotorcraft. Although I can see why the insurance companies would shy away from covering damage from autorotation training.
Bruce Tuncks Posted January 30, 2021 Posted January 30, 2021 Something I've wondered about gyros... What is the reason they seem to have a lot of accidents? They are advertised as being real safe. This is only for interest's sake... they are not the sort of "go places" flying I like, but their ability to land anywhere sure is impressive. There are none around here, so I don't know much about them.
old man emu Posted January 30, 2021 Posted January 30, 2021 I'll be corrected, but I believe that a lot of gyro crashes are the result of our old mate, stall/spin. People forget that a the spinning main rotors create a revolving "fixed" wing, and that the rotor will stall just like a fixed wing. I hope a gyro pilot can expand on that. 1
Russ Posted January 31, 2021 Posted January 31, 2021 No...they don’t “stall”.....pull off power to zero airspeed, blades no longer able to sustain current height, machine now vertically descends, keep a tad of rudder to stop rotating, and down you sink ( vert drops ) safe as, but not desired landing procedure, machine will bounce on ground, likely to then roll on ground, plus bend undercarriage etc etc. Mindset is different in a gyro.....you must be saying “ can i take off from there”......you can almost land a gyro anywhere. This mistake by pilots is not uncommon, they’ve landed and realise they’ve got problems getting off again, too short, too rough etc etc, so they “have a go”, they “rush” the blades to get to flying speed, they stuff up good training procedures, they “flap” blades etc, and it all turns to shit. “Dead stick” landings are taught and easy, pull off all power, drop nose to maintain a nice airspeed, say 40...50 ish, manoeuvre as required to get onto a “final” then finals you go, easy as. If......your too high, just reduce airspeed and vert drop as required, then again rebuild airspeed to proceed to touchdown.....easy as. The vast majority of gyro stuff ups are pilots not doing as they were taught, they get too complacent they get cowboyish, they might get away with that at times, but it will one day bite them. Blade management is seriously taught, do all the right things, and gyros are a hell of a machine, love shit air, stable as, widely used by grazing industry, cheap to run and maintain. Many many gyros embark on epic trips, they just dont make a song and dance about it. 2 2
Yenn Posted January 31, 2021 Posted January 31, 2021 I have never flown a rotating wing aircraft, but I have heard that it is esy to kill yourself in a gyro, by doing what we do by instinct in a fixed wing. If they lose rotor sped and begin a rapid descent, then pushing the stick forward will not be the life saver that it is in fixed wing. It will stall the blades and result in no lift at all. Pulling back will cause the blades to increase their rotation.
old man emu Posted January 31, 2021 Posted January 31, 2021 31 minutes ago, Russ said: they “flap” blades etc I think that is what I was getting at when I suggested that the lift of the rotor could be lost in a similar way to a fixed wing stall - AoA too great. Would you enlarge on "flapping the blades", please?
facthunter Posted January 31, 2021 Posted January 31, 2021 A plane with speed has kinetic energy (energy of motion) The extra speed (margin over stall) will permit a flare. With a Heli you have collective pitch and that will let you speed up the rotors as you lose height and you can flare it onto the ground if there's enough "wind up" of the rotors and they are heavy enough and you time it right, change the collective and for a short time get excess lift. A gyro has no ability to change pitch. It's always fixed in the design, so cannot stall but without forward speed, there's no excess energy to trade for the flare.. so NO flare. The RoD can be survivable . If you make the right approach the landing can be achieved in a very small distance and they handle gusts etc very well.. A powered rotor spin up makes the take off short as well but it can never be a vertical lift off except maybe in a gale. Nev
Russ Posted January 31, 2021 Posted January 31, 2021 Yen......the golden rules.....dont do power push overs, dont introduce purposing, don’t rush your blades ( startup ) Blade flap.......gee how to simplify it, here goes.......at very low rpm as your taxiing to get blades to flying speed, if you rush the blades, the advancing blade generates too much lift to allow the retreating blade to teeter enough to balance that lift, that retreating blade hits it’s stops whilst that advancing blade is still teetering up, then things get nasty. Blades over flex, the power building there is massive, it starts to break things and worse........so don’t rush the blades at low rotations, easy does it, as they gain more rpm add on more power, then more power etc, training will teach you the tell tale signs of how “to manage your blades”.....it’s not hard at all, remember your trainings. Most machines these days have a type of “prerotator”, elec or belt driven etc, this has been a huge plus for gyros. Some systems get the blades to just under flying speed, bloody brilliant. Get blades absolutely honking, brakes full on, release brakes, full power, your airborne in just a few metres, some guys get off in 20m every time. Losing rotor speed.....without airspeed your blades automatically are starved of lift, they slow you sink, thats normal. they never slow to dangerous never, impossible, they are now getting a reduced feed of air as you sink. Pushing stick forward is the norm to regain some airspeed, 100% safe,normal. Add on power and off you go again. The prime controller of height is power, the prime controller of attitude / speed is stick, combine the 2 ( power,stick ) in your action, all’s good. With experience a half decent pilot can do a 180* turn in the length of the machine, even a 360*. Again same pilot can “load up blades” and hover for a time in and around trees etc. Gyros can easily sucker some pilots into manoeuvres etc that are beyond that pilots capabilities......but absolutely doable. The available windows of operation is often the undoing of an unwary / low skilled pilot. 1
spacesailor Posted January 31, 2021 Posted January 31, 2021 Thats the way l saw gyros, playing TAG around the TREEs, then up over the top, diveing down, around the treebase, & under branches, rotors nearly cutting leaves. Great show of skill. spacesailor
old man emu Posted January 31, 2021 Posted January 31, 2021 13 minutes ago, Russ said: Blade flap I might have to do some reading on how rotary wings work, but I can see the logic in what you are saying there. So what is the cause of loss of control whilst airborne? What's a power pushover?
facthunter Posted January 31, 2021 Posted January 31, 2021 Maybe that's indicative of why they are considered to be unsafe, The situations they get in.. The concept and examples have been around since the mid 30's. ALL so called rotary wings have a problem with advancing and receding blades as they move horizontally in any direction as they get a large change of airspeed over the blade(s) each revolution and that makes the advancing ones want to slow up more and produces a lot of flexing and out of balance of the rotor system. Blade fatigue failure is not unknown. The name "Crazy Palm Tree" is not for nothing. Nev 1
Russ Posted January 31, 2021 Posted January 31, 2021 At fact.........Blades have an infinite life, the hub bar is the worker, hence they must be crack tested ( X-ray or dye penetration ) every 500 or so hrs, or whatever the manufacturer states, could be even more / less. Blades........the system is a “teetering” system, they tilt left / right whatever, the retreating blade balances the advancing blades lift to give a perfectly balanced inflite operation. Gyros generally have a VNE of less than 90kts, so this teetering system is fine with that, 100% ok. If gyros were to get to much higher speeds then the rules change, matters like retreating blade stall and other dark matter comes into play ( go googling for info ) So gyros are powered / designed to never get to the higher extremes. Sorry got carried away....also meant to say.......”they do not get out of balance” they’re singing along teetering up/down creating a perfectly functioning platform, the pilot has no control whatsoever on this operation, it is self managed within the system design. Comparing gyro design / training etc, from yester yrs to now, is comparing chalk to cheese. One European makers machines are IFR night rated, will never see the light of day in australia, casa would baulk. ”Crazy palm tree”....never heard that analogy before, but heard lots of fictional / untrue comments over the yrs, lots of them. 1 1
waraton Posted January 31, 2021 Posted January 31, 2021 Shame ASRA has shut down its forum again, was heaps of great info on Gyros there. BFRS with ASRA now require pilots to complete and pass the human factors exam every time you do one. Not required with any other organisation, including CASA. 1
Russ Posted January 31, 2021 Posted January 31, 2021 @ wara ........i heard asra had abandoned a vital service ( forum etc ) why ???? It’s just crazy logic. Folks lurking / seeking info have lost a great service. The “HF” is another strange logic, new faces onto committees etc can bring crazy ideas sometimes. asra began a strange pathway about 10yrs ago, has resulted in many members being disappointed. Safety has always driven asra, and thats a good thing, instructors are regularly assessed to maintain standards, thats another good thing. The cost of some machines blows me away, almost half the cost of a half decent 44 with good hrs to run. 1
spacesailor Posted January 31, 2021 Posted January 31, 2021 (edited) They say, Trikes, hang gliding & powered parachutes, have the same Deadly accident rate !. Just the same as motor bikes. Do we take any notice. spacesailor Edited January 31, 2021 by spacesailor Missed word
facthunter Posted January 31, 2021 Posted January 31, 2021 (edited) Why would a blade NOT bend when the airspeed is so varied along it's length? ALL things behave as if they are rubber. Spacey I don't think I've asserted they are particularly unsafe and can fly unpowered or with tail rotor failure, in the case of a heli..Nev Edited January 31, 2021 by facthunter
spacesailor Posted January 31, 2021 Posted January 31, 2021 BUT Havent we all heard those Horror stories ?. spacesailor
Russ Posted January 31, 2021 Posted January 31, 2021 11 minutes ago, spacesailor said: They say, Trikes, hang gliding & powered parachutes, have the same Deadly accident rate !. Just the same as motor bikes. Do we take any notice. spacesailor Who’s “they”.........lots of “stories” get spread out there, some are true, many false, many exaggerated. 1
Russ Posted January 31, 2021 Posted January 31, 2021 9 minutes ago, facthunter said: Why would a blade NOT bend when the airspeed is so varied along it's length? ALL things behave as if they are rubber. Spacey I don't think I've asserted they are particularly unsafe and can fly unpowered or with tail rotor failure, in the case of a heli..Nev They do, they “cone up”
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