I'm pissed off! I just wrote a huge answer to each point ... loaded another web page in the mean time and closed my browser - been fishing around in caches and history can't find it.
AND then I finally read that report and realised that it would appear Lu does not really understand these topics (though he has spotted some ammature mistakes in other people's reports ... which always makes us feel important)
So briefly:
Re Point 3: No!
"A Simple Definition of Fatigue
Fatigue can be defined, in engineering terms, as a mode of failure that involves the nucleation and growth of a crack in a structural component undergoing loads that vary with time and whose maximum amplitudes induce stresses that are equal or lower than the expected yield strength of the material used. From a more "scientific" point of view, fatigue is the characteristic behavior of a material undergoing variable loads, from both the deformation and fracture points of view, and includes the study of topics such as: cyclic plasticity, localization of deformation, dislocation structures, crack nucleation, crack propagation, and any other phenomena produced by variable loads.
The key point is that loads must change with time in order to have "fatigue" as described above. This makes fatigue a widespread phenomenon in today's technological society, where countless artifacts and devices, from the space shuttle to many children's toys, are subjected to loads whose amplitudes and forms change with time."
KEY PHRASE: "....lower than the expected yield strength of the material used."
So this key final mast event is just not fatigue! - OK !? (Lu:"...what do you think causes the rotor mast to fracture.[?]" - NOT FATIGUE !!
(control system - ONCE ever... maybe, but no evidence ... you know the ONE ... still sad though)
Point 4.
We do! It doesn't. Not theory ... actual practice. - acknowledge ! (?)
Point 1. Ask the engineers:
I have now talked to them (I think they maintain more than anyone else) - they say it is possible over time to keep winding on excess pitch on adjustment - it'll fly 'normally' but will have reduced auto revs. I test fly them for that - never remotely had a problem. Now AUGUSTA rotor heads CAN be catastrophically incorrectly assembled ! And so can many things if you don't know how to do it. Apparently after you've done the first one on a Robbie its easy and simple thereafter. There IS NO EVIDENCE that this is a problem, and there would be in the wrecks - there is not! this is a RED HERRING!
Point 2. Not a Pilot:
Well I won't be cruel here - at least you've touched a stick. But A LITTLE KNOWLEDGE IS A DANGEROUS THING - (or know your limmitations) humility in the face of ignorance would win more respect for your views. Learn to fly one - it'll teach you alot (R22 will teach you to be pretty sharp - very responsive (this is a good thing if you can and a bad thing if you can't!)).
Point 5. What 'spools up' must 'spool down':
Well if you were a pilot you would know that RRPM is the most important thing in the world. The lower it is the more angle of attack is required. When the angle of attack is TOO big the blades stall and it is unrecoverable in any helicopter even with full power (except in unusual circumstances). To slow the rotor you have to be demanding more (energy) from the rotor than you are putting in to it (energy input could be engine, height or speed). If the energy you consume is RRPM then it had better be a fairly short term policy, or you had better be very near the ground, or you will probably die ... SIMPLE CONCEPT (not much different than remembering which way to turn the steering wheel of a car when the road bends to the left). I like the fact that it reminds you quickly before much energy is lost and then it hardly needs any energy to get it back again. (SOME PEOPLE like to sit in their flying armchair and contemplate what they are going to do about the steadily falling RRPM - fine but by the time they decide to DO SOMETHING they are going to have to 'rob a bank' to find the energy they need to replace the missing RRPM - and then there had better not be anything pressing because they're going to have to wait.....I prefer LOW INERTIA!)
Point 6. Well I'm not a flash bloke needing a Ferrari. The (r44) performance IS great - faster than B206 for HALF the fuel burn. Big margin between power allowed and what the engine can do (and it doesn't go 'POP' if you have to go there - ROBUST). Low revving - compared with other apps of same engine. (enough? - no? try hover at MAUW in B206 next to R44 .. look at margin).
Point 7. H369 changed from sensible shape to marketing nose job - never could understand that - Sadly I am a member of the 30% of people who thing functional elegance is beautiful. Boy the R44 is SLIPPERY ! (Any helicopter more so? Why are they all such illogical shapes?).
Point 8.
We all KNOW it can do this. - engendering fear of the edge in people is just fine... but don't USE that to beat them with
This new stuff about fatigue and wear in the mast and head - OH COME ON! Sure bearings wear - they get replaced! Mast are NOT failing through fatigue! - even though you wish they were - they DO NOT .. ARE NOT (I AM FATIGUED THOUGH!)
Incidentally - if you were fundamentally wrong ... could you admit it? .. I think I could but I think it would be harder for you... Anyhow I don't think I'll have to - and I doubt if you can... (now after so many years invested in this half baked 'anti theory'.)
I think you seem to half understand the subject - but not enough - to much 'black art' in your stuff - not enough understanding. I think you are clearly sincere in your belief. I wouldn't try and start designing helicopters though !!
Keep up the good work ... always good to stir a little thought in people..
Relax
C Ya
JOE
Robbies:
1.There are no misrigging accidents! (you can tell this by examining the wrecks)
2.You can fly it normally (perhaps a little sportily) - no problem.
3.You can massivly exceed cert. criterea (to prove certifiability of course) with no detrimental effect.
4.Fatigue problems are not a significant issue (you can tell this by examining the wrecks)
Chill..
[This message has been edited by JoePilot (edited 26 September 2000).]