Back to Lu:
Again, your words are capitalized.
IF YOU WILL NOTE I MADE A POST ON ANOTHER THREAD AND I CHANGED THE
WORDING RELATIVE TO HOW CONING IS INTRODUCED.
I am not going to go trying to find what you have edited.
I ALSO ALLOWED THAT WITH CONING, THE BLADES WOULD LEAD SLIGHTLY BUT
UNDER THOSE OR ANY OTHER CONDITION WOULD THE LEADING CAUSE THE
ROTOR SYSTEM TO ACCELERATE ENOUGH TO READ THE DIFFERENCE ON YOUR
TACH OR PERCENTAGE OF POWER OR, WHATEVER.
What does that have to do with the price of tea in China?
WHAT DIFFERENCE DOES IT MAKE HOW MUCH THE BLADES CONE WHEN THE
PILOT PUTS THE HELICOPTER IN A HOVER AND 90 DEGREE PITCH HORNS ARE
INSTALLED?
Duh!? YOU are the one who said pitch cone coupling was going to practically double the amount
of actual pitch in the blade. Obviously, if we want to figure out the ACTUAL amount of exess pitch
then we need to know how much coning there is, because the amount of exess pitch is directly
dependent upon the amount of coning, hence, the term pitch-cone coupling. Have you been checked
lately for the possibility of alzheimers disease?
AND WHAT DIFFERENCE DOES IT MAKE HOW MUCH THE PITCH WOULD BE
INCREASED OVER THE AMOUNT INPUT BY THE PILOT WHEN HE PULLED
COLLECTIVE WHEN A 90-DEGREE PITCH HORN IS INSTALLED?
YOU are the one who said pitch would practically double, remember? In fact, here is your exact
quote:
AT THE SAME TIME, THE CONING ACTION WITH A 90-DEGREE PITCH HORN WOULD
PRACTICALLY DOUBLE THE PITCH RESULTING IN BLADE STALL OR VERY CLOSE
TO BLADE STALL. IF THE PILOT HAD SUFFICIENT POWER TO GET THE HELICOPTER
OFF THE GROUND AND MOVED THE CYCLIC IN ANY DIRECTION HE COULD ADD
ANOTHER 5-6 DEGREES OR MORE TO THE ALREADY HIGH PITCH IN THE ROTOR
SYSTEM.
And you are asking me what difference it makes? Well, Lu, explain to me how something that
makes no difference can result in “BLADE STALL” or very close to it. If it makes no difference
then what was your reason for pointing this out in the first place?
YOU ARE TRYING TO PROVE ME WRONG THROUGH THE USE OF YOUR
CALCULATIONS, WHICH MAY IN THEMSELVES BE VALID, (ACCEPTING THE
FIGURES USED IN THOSE CALCULATIONS).
I have already proven you wrong, you just refuse to accept it. Who is beating the dead horse here?
YOU ARE BEATING THE PROVERBIAL DEAD HORSE. FRANK ROBINSON COULD
NEVER HAVE CERTIFIED THE USE OF A 90-DEGREE PITCH HORN ON HIS
ROTORHEAD AND IF HE DID THE FAA WOULD NOT APPROVE IT.
Yes Lu, I've heard you say that like ten different times now, but you have given no valid evidence to
substantiate this claim. In fact the very reasons you did give as evidence that it could not be certified
are above and you are now asking me what difference they make. I don’t know, that is a good
question. What difference does it make?
ASIDE FROM THE COLLECTIVE PITCH COUPLING ADDING PITCH WHY DON’T YOU
RUN YOUR CALCULATIONS CONSIDERING CYCLIC PITCH CHANGE? I BELIEVE
THAT YOU OR ANOTHER INDIVIDUAL STATED THAT RE-RIGGING THE
HELICOPTER COULD SOLVE THE PROBLEM. THE RIGGING PROCEDURES, AS BAD
AS THEY ARE, HAVE BEEN APPROVED BY THE FAA. YOU WANT TO CHANGE THE
FAA APPROVED RIGGING TO ACCOMMODATE A 90-DEGREE PITCH HORN THAT
THE FAA WOULD NOT APPROVE OF IF FRANK ROBINSON PROPOSED IT.
First of all, I am not talking about rigging PROCEDURES, I am talking about the rigging itself.
The PROCEDURE for setting up the length of control rods and the actual resulting lengths are two
different things. No, I don't want to change the rigging to accommodate a 90 degree pitch horn. I
am saying that if it had been done that way, the rigging would be slightly different. Actually, with
as little difference as the 90 degree horn makes it may not even need to be rigged differently.
Run my calculations considering cyclic pitch change? There is nothing to calculate in regards to
cyclic inputs as the flapping they produce does NOT induce a pitch change with a 90 degree pitch
horn. However, with the 72 degree horn, which it has actually been certified with, pitch change will
be induced by cyclic flapping. This is called Delta 3. The R22 flies just fine with it as have some
other helicopters.
ANOTHER POINT MADE BY YOU OR ANOTHER INDIVIDUAL, RELATED TO THE
CONING, ONCE SET BY PULLING COLLECTIVE WOULD STAY THE SAME WHEN
CYCLIC WAS INTRODUCED CAUSING THE HEAD TO TEETER AND THE CONING
RELATIONSHIP WOULD REMAIN THE SAME RELATIVE TO THE HEAD.
Exactly! You’ve finally made a true statement but you don't even agree with it.
FIRST OF ALL, THE HEAD IS UNDERSLUNG JUST LIKE ON A BELL AND THIS IS DONE
TO MINIMIZE LEAD AND LAG. HOWEVER THE BELL JUST TEETERS BUT IT DOES
NOT HAVE CONE HINGES. SO, THIS UNDERSLINGING WORKS FOR THE BELL. BUT,
SINCE THE ROBINSON BLADES CAN FLAP ON THEIR CONE HINGES THEN YOU GET
LEAD AND LAG.
True, the Bell does not have coning hinges. But does this mean that the Bell blades do not cone? Of
course they cone. They cone by bending. Now you tell me, is it the coning hinge or coning itself
that generates the coriolis force to lead or lag the blade?
As for which hinges the movement will occur on due to cyclic flapping on an R22? Imagine if we
took an R22 and hooked a cable onto each blade tip. Then we fastened the lose end of one cable to
a point up high on a wall. Then we hooked the other cables free end to some sort of winch that can
pull 22 thousand lbs on the cable. We have set the fastening point and the winch at some height
above the top of the helicopter so that as we put tension on the cables the helicopter will lift off of the
ground. The tension on the cables connected to the blade tips will simulate the centrifugal force at
flight RPM. By picking the whole thing up we are simulating the lift that would be created in a hover.
Now, if you were to climb into the helicopter, coning would increase, movement would occur at the
coning hinges but not the teetering hinge (ok, the cg change from you getting in would cause
movement at the teeter hinge, but you see my point, and if we added the weight right where the cg is
then it would not move the teeter hinge). Now lets think about cyclic inputs. Cyclic tilts the rotor
tip path plane. That means that when one blade goes up the other goes down. If we could then tilt
our contraption holding the tension on the cables we would simulate tilting the tip path plane. With
this picture in your mind, which hinges do you think will have the movement? I think it is obvious
that the teeter hinge will move and the coning hinges will not. Imagine how much force it would
take to misalign the hub from the tip path plane with all of the centrifugal force pulling on it. Just as
a rotor blade gains stiffness from centrifugal force, so do the coning hinges gain stiffness. If they
didn’t the blades would simply fold up as the helicopter tried to attain flight. Granted, there
probably is a VERY small amount of movement at the coning hinges. But not I think any more then
there would be on the bell from flexing.
HOWEVER, THE ROBINSON ROTORHEAD DOES NOT HAVE LAG HINGES SO THE
LEADING AND LAGGING TAKES PLACE VIA SPANWISE BENDING OF THE BLADES.
This is true, but also true for the bell and all teetering rotor systems. Underslinging reduces the coriolis effect but does not
eliminate it. And coriolis force is what causes lead lag forces.
THIS BENDING IS REACTED BY THE CONE HINGES AND THE TEETER HINGE WHICH
CAUSES THEM TO WEAR EGG SHAPE. ANOTHER REASON FOR THE CONE HINGE IS
TO RELEIVE BLADE BENDING AND MINIMIZE THE TRANSMISSION OF FLAPPING
LOADS INTO THE AIRFRAME.
True, the coning hinge is there to reduce blade bending from coning. But where did you come up
with them minimizing flapping loads into the airframe? As for the coning hinges wearing, can you
name a helicopter that does not have wearing parts?
SO, IF THIS IS TRUE THEN FRANK ROBINSON ADMITS TO THE BLADES FLAPPING
AND WE ALL KNOW THAT WHEN BLADES FLAP THEY LEAD AND LAG.
Of course the blades flap, but they flap on the teetering hinge. And yes they will lead and lag just
like they do on a bell or any other two-bladed teetering rotor system.
THE CONE ANGLE DOES NOT REMAIN CONSTANT. IT CHANGES DUE TO CYCLIC
INPUT AND BLADE LOADING AND WHEN THIS HAPPENS, THE BLADES WILL TRY
TO LEAD AND LAG.
Coning does not change from just a cyclic input, it’s only when the cyclic input causes rotor
thrust (loading) to change. And also, with CONING, both blades lead at the same time or lag at the
same time which translates into RPM changes not bending stress. And in fact the RPM doesn’t
change much because the governer compensates.
Final Note:
My purpose here is not to prove you wrong. I was trying to get you to stop making a fool of
yourself. You were presenting theories that were so blatantly flawed and with little evidence to back
them up and then so strongly defending them. Multiple people on this forum tried to straighten you
out. But you just kept getting yourself in deeper. Then you present your credentials as evidence
that what you say must be true. Now that really makes you look like the buffoon that someone
called you earlier. But the fact is I’ve let myself get drawn into this silliness, and I see now that it is
pretty pointless. So I’m not going to keep going on with you. Besides, I don’t know enough to really do justice to how complex helicopter dynamics are in reality.
I’m just a high school drop out without a college education trying to make a living flying these silly
contraptions (I say that with the utmost affection). So, what do I really know anyway. I know how
much credentials mean to you, so I doubt I could carry much weight in your mind in convincing you
of your errors. Dealing with your irrationality is too frustrating as you can tell by the tone of my
responses. Everyone else has figured this out already, that is why no one is posting on this thread
anymore, I’m just a late comer, but I finally get it.
Bye Lu.