Lu,
Thanks for posting the POH. Nothing I have said seems to disagree with it other than the application of aft cyclic. It has shown me where you get the idea that flapping is so dangerous. As it says Lu, excessive flapping occurs during the sideslip of the aircraft. Same as I stated above: flapping is due to the acceleration/deceleration of the disc NOT due to cyclic application as you continue to assert. Sideslip is accelerating the disc in the direction of the sideslip causing a new flapping to equality to occur (which will be barely noticeable to the pilot), and flapback in that direction which will be noticeable, coupled with the attendant fuselage roll, and pitch up or down dependant upon rotor direction. The pitch can actually be quite severe, but is often not considered. It is these forces that add to the danger of mast bump. Cyclic application is not the same thing as side slip.
Summary: Cyclic input does not cause excessive flapping, sideslip can. Again – I think you have some fundamental misunderstandings about flapping. I will put my two cents worth in the other thread from DJ as well.
Lu, you say: >>Many of your objections to my comments are based on your knowledge of Bell flight theory and using that logic; you question or object to my postings about the Robinson.<< I agree to a point, but my objections are based on rotor theory, not just on Bell systems. I fundamentally reject some of your basic propositions – such as that the disc goes “wild” during zero G. You base your theories on these fundamental flaws, hence I take issue with them. I would like you to go back to the point form above so we can continue to nut out these issues, rather than meander onto generalisations.
You said >> Tim Tucker who was a test pilot during development of the R22 also teaches many safety courses. He tells the students to add a tad left cyclic when pulling back on the cyclic to load the main rotor. No other instructor has his experience or technical background and in their ignorance or whatever they follow the instructions in the POH.<<
As I said previously in reference to Tim Tucker, He knows his stuff and I don’t. I can only teach what the manufacturer recommends and what I can justify. Just curious though…if he was the test pilot, why did he not ensure that the POH included the application of left cyclic so that everyone could benefit from his results? Would be great to get him on pprune to hear what someone of his experience has to say.
You then say >>The POH says to bring the cyclic back without adding any lateral cyclic. If it can be proven at some later date that the 18-degree offset of the control system is a factor it can be proven that Tim Tucker was right and if you did the control movement in accordance with the POH you could increase the right roll rate. A highly experienced pilot could possibly recover from this situation. However if a newbie enters this condition he will most likely instinctively push the cyclic left and chop off his rotor or the tail boom.<<
This confuses me Lu. You say that a highly experienced pilot could recover from an increased right roll rate due to using the POH technique, but then you say a newbie will roll left and chop the tail boom off. Firstly, how does the experienced pilot recover from the right roll without using any left cyclic? Secondly – isn’t the newbie using Tim’s technique? What did you mean here? Thirdly - I believe mast bump would be the result, not chopping off the tail boom (although that may indeed occur subsequently).
Lastly you ask: >>one question. How many Bell Helicopters have a restriction against sideslip and out of trim flight?<<
The UH-1H certainly does, and I believe the 212 as well. It is something like “application of full pedal above 80 KIAS is prohibited”
Also it has prohibitions against negative or zero G manuevers as well as something about the rapid lowering of the collective from 45 psi will cause a pitch down and roll right and possibly mast bump. Any Huey/Bell gurus, please correct me if I am wrong.
In other words, the Bell does have restrictions WITHOUT an 18 degree offset OR conning hinges. What do you know?
Edited for (some of the ) spelling.
[ 30 October 2001: Message edited by: helmet fire ]