To: Nick Lappos
Your post is so full of misguided assertions it is hopeless to respond. The fact that you cannot tell the difference between the trimmed cyclic position and the response to a stick input shows that explaining all this to you is truly hopeless. I only hope the readers have the sense to consider that when you make the points you do.
Response:
I asked if the static trim position of the cyclic had anything to do with the direction in which the disc would tilt. I referenced the FAA document, which stated that disc movement is in the same sense of cyclic movement. If the cyclic is right of the rigged neutral longitudinal axis then which way is the disc tilted if it is tilted any way other than down over the nose.
As you put it "the only way I can make that determination is to perform the test."
The thought of you determining something useful from your "test" is a joke, right?
Response:
The test when performed will be accomplished by a CFI with high time in both the R-22 and R-44. I will document the test to be performed and he will evaluate those instructions to determine if the test is doable. If the test can be performed without endangering the pilot or the helicopter the test will be performed. The individual is familiar with test and development requirements and he will fully document the test and the results will be published on this forum.
You say "let's say you get promoted to the head of flight test...." Lu, I was the head of flight test, in fact the head of all test at Sikorsky!
Response:
Now that you have told everybody about how important you are and what you have accomplished please answer the question. How would you respond to the engineering department when they told you that testing was unnecessary?
I used that analogy to point out why I have been so hardheaded. Especially since you make statements without being familiar with the design of the Robinson rotorhead and the complications arising from that design.
Another point is that you did not respond to my other comments in the response dealing with delta hinge effect and what I perceive as a design problem with the rotorhead that contributes to mast bumping and / or fuselage incursion.
Regarding the so-called 18-degree offset, it has absolutely no connection with mast bumping or fuselage incursion. If the offset exists and the pilot has to compensate for it then you could have a problem in zero G recovery. The problem with the R22/44 is that you can easily induce high flapping loads and the design of the rotorhead couples up with these loads and kills people. The Robinson helicopters are the only helicopters that are restricted from out of trim flight and sideslip at all speeds. Violate these SUGGESTIONS and you get high flapping loads as a result. Why don’t you comment on these facts?
Here is another question. On the various Sikorsky designs you are familiar with what is the +/- flapping range in relation to the static droop stops? I will assume that there is a +/- range on all of them but on the Robinson there is a + range but there is no negative range. Do you see any potential problems with that under high flapping excursions?
One of the reasons I feel so strongly about the 18-degree offset is that the Lynx helicopter has the same problem. Its’ offset is 15-degrees and the Lynx is rigged just like the Robbie in that the blade is offset during the rigging procedure just like the Robbie. On the Lynx from what I understand they have some type of stabilizing black box that reads cyclic input and adjusts the servo input to compensate for the 15-degree offset. If the black box fails the input of forward cyclic or any other direction the helicopter will roll 15-degrees after the direction of cyclic input. It is because of this that I believe the Robbies have the same problem even though you state that they don’t.
[ 05 November 2001: Message edited by: Lu Zuckerman ]