I didn't read all the inputs on this subject. But surely someone looking after their aircraft would understand that the poor old tail rotor is not designed for that sort of treatment.

It's all very well to get away with it in a Hughes 500 or R-22 on occasions, but put yourself in a S-61 or CH-53 where you still apply the same theories of flight to the tail rotor. You can do that manoeuvre in these aircraft, but you had better let the next pilot or engineer know that you may have stressed the aircraft.

No pilot worth his salt is going to kick the arse out of a helicopter to get the job done, as there is a fine line to that envelope where you're a professional or one of those other guys.

But: That manoeuvre you mentioned, if you're in the **** , of course it'll get you out of it.

MERRY CHRISTMAS!!

Bintang.,

We may be on different wavelengths, but the manouevre that I would understand would be rolling the helicopter into a turn, with the main airflow through the disc being adjusted so the helicopter is then facing sideways (within 60 degrees or so) to the direction of travel. The braking action through the rotor disc then is controlled with the collective and cyclic, much as for a normal (forward) fast stop. Pedal input should be no more than any normal turn, it should only be there to balance the intial roll, and maybe a tadge extra to hold the fuselage slightly out of balance during the sideways flare. a reversal of pedal input to straighten the helicopter into wind at the cessation of the manouevre, plus an anticipation of power back into the hover.

There should be no undue airframe or dynamic stresses at all. Emphasis on should ;)

Lu is STILL not listening!

FAR 27.351 (and all other FAR/JAR) does NOT call for any testing of full pedal inputs!

The FAR that Lu incorrectly reads says:
"Sec. 29.351 Yawing conditions.
(a) Each rotorcraft must be DESIGNED FOR THE LOADS RESULTING FROM the maneuvers specified..."

Lu, I made the words bigger so even you can read them. That is a design condition, so the designer calculates the loads due to the hypothetical maneuver, and then makes sure the helicopter can stand the loads. It is not flown! I met with an international committee three weeks ago to discuss this paragraph in FAR/JAR and help re-write it, so I THINK I know what it says.

I cannot make you understand it, however, that is a lost cause. Please do not mislead the group into thinking that such abuse is tested, because it is not, and your foolish misunderstanding (after having been told several times) might cause someone to go and do it.

You are dense, Lu, to not even read or understand what YOU post!

To: Nick lappos

Nick Sez:

“FAR 27.351 (and all other FAR/JAR) does NOT call for any testing of full pedal inputs!
The FAR that Lu incorrectly reads says:
"Sec. 29.351 Yawing conditions.
(a) Each rotorcraft must be DESIGNED FOR THE LOADS RESULTING FROM the maneuvers specified..."

Lu Responds:

Nick I would strongly suggest you read my post. Your statement above is 100% correct as it reflects FAR 27.351. If you look closely at my post shown below I quoted AC-27-1, which is the Certification of Normal Category Rotorcraft. Get a copy of it and read under paragraph 27.177 titled Static directional stability. Paragraph a. reads EXPLANATION. This rule requires that positive static directional stability be demonstrated at the TRIM airspeeds defined in 27.175. The trim speed for climb is Vy and for cruise 0.9Vh or, 0.9Vne (whichever is less). The next two paragraphs and sub paragraphs describe the test setup and the test itself and these tests are required for certification. I would also suggest you read paragraph 27.175 as it sets the groundwork for the test. Also, read the Code of Federal Regulations quoted in my post. I think you will find this reading enlightening.

My original post:

AC-27-1 paragraph 27.177.b.2 recognizes that some helicopters experience excessive flapping of the main rotor and tail rotors when the helicopter is in a sideslip. To establish this side slip/flapping limits the respective rotors should be instrumented. CFR-14-27.177 requires testing of the controllability at side slip angles of plus ten degrees, left and right, and CFR-14-27.351 requires full deflection of the tail rotor pedals (left and right) while airborne from 0 to 0.6 Vne to attain a 90-degree sideslip.

What is your favorite flavor?

Lu, did you write the words "and CFR-14-27.351 requires full deflection of the tail rotor pedals (left and right) while airborne from 0 to 0.6 Vne to attain a 90-degree sideslip" ??


Did you? If you did, you were wrong. Period.
I guess you didn't mean "while airborne" to infer that this is flown, in the air, above the ground, while airborne. I guess you don't know what you mean.

Why do you keep on pretending you know what you are talking about when you don't even know what you said? Do you think we don't know what you said? :confused:

To: Nick Lappos

Nick Sez:

“Lu, did you write the words "and CFR-14-27.351 requires full deflection of the tail rotor pedals (left and right) while airborne from 0 to 0.6 Vne to attain a 90-degree sideslip" ??

Lu Responds:

"AC-27-1 paragraph 27.177.b.2 recognizes that some helicopters experience excessive flapping of the main rotor and tail rotors when the helicopter is in a sideslip. To establish this side slip/flapping limits the respective rotors should be instrumented. CFR-14-27.177 requires testing of the controllability at side slip angles of plus ten degrees, left and right, and CFR-14-27.351 requires full deflection of the tail rotor pedals (left and right) while airborne from 0 to 0.6 Vne to attain a 90-degree sideslip


The above text was taken from a report that I sent to the NTSB in 1996. It paraphrases the requirements of the two documents. In my response to your last post I provided text directly from the two documents. I used the term airborne to define the conditions under which the tests were to be undertaken.

In one of your posts you indicated (if I remember correctly) that it was not required to perform a test while airborne (my words) in order to prove the structural integrity of the helicopter by applying full left and right pedal to attain a 90-degree sideslip. Perhaps I misunderstood your statement but CFR 14.27.351 states exactly that. I don't have the time to type out all of the text but I am sure you have access to CFR 14.27. In my book it is on page 490.

SINCE YOU USED CAPITAL LETTERS FOR EMPHASIS I WILL DO THE SAME. YOU MENTIONED PARAGRAPH (a) OF CFR 14.27.351INDICATING THAT EACH ROTORCRAFT MUST BE DESIGNED FOR THE LOADS RESULTING FROM THE MANEUVERING SPECIFIED AND YOU STOPPED THERE ALLUDING TO THE FACT THAT I WAS WRONG AND THAT THERE WAS NO TEST REQUIRED TO DEMONSTRATE THIS CAPABILITY. WHAT YOU DID NOT DISCLOSE WERE THE PARAGRAPHS AND SUBPARAGRAPHS THAT FOLLOWED (a) WHICH FULLY DEFINE THE TEST AND THE SIDESLIP ANGLES OF +/- 90-DEGREES AT .6Vne. AND, CONTRARY TO WHAT YOU SAID PREVIOUSLY THIS TEST APPLIES TO ALL CIVIL HELICOPTERS.

There are alligators and humming birds. You are a combination of the two. An alligator mouth and a hummingbird butt.

Stop trying to tell everybody I am wrong when you have not even read the documents that I have quoted.

John,
There's a bun fight going on around us, but I should say that I posted the last one with a bit of "tongue in cheek".
Your numbers and physics are beyond me, but you did put them in arms and legs conversions. Basically, I think I was trying to say on the discussion was that, despite what your best mate at the flying school said, please listen to the old farts. That bloody tiny tail rotor on your R22 suddenly turns into that small thing at the back when you're flying a Skycrane.
There was a case a couple or so years ago when a CH-53 went into a highish hover next to a hill, (with a slight breeze, but that became important)
and then spiralled down killing everyone.
Tailrotors have to be respected, that CH-53 crew had no idea how sensitive they can be.
Nick, if you're still listening. How the hell can you crash coming to a hover in one of Sikorsky's finest aircraft. What happened there? I heard it was loss of tail rotor control.
Today, everyone takes the tail rotor for granted. <img src="cool.gif" border="0">

i think a sideways flair would be the same braking as a normal flair only you can do it closer to the ground, same as flairing backwards. the only reason that it may be hazardous is that engine failure might catch you on the skids sliding sideways or backwards(definate no,no) and flairing backwards hard can make you run out of rear cyclic as you try to bring it to a hover. also the trim shouldnt move much if you do it properly i would think. <img src="tongue.gif" border="0">

Lu

AC29 = Advsiory Circular - it is advisory and an evolving document - the FARs and AC are written by aerospace professionals with a knowledge of current design and safety trends - Nick is one of those men, therefore whatever you say as far as I'm concerned he holds ace of trumps to your 2 of spades (with which you dig your holes).

Happy Christmas.

bintanglagi,
That H-53 accident (which was captured on home video, if we are refering to the same mishap) was actually a pilot induced oscillation problem, where the aircraft was shaken to the point of structural failure by a combination of pilot wiggling the collective (involuntarily) to create a tremendous vibration and the tail boom failing as a result. The pilot actually aborted the first landing for the same reason, but on the second attempt pressed on. I cannot remember what contribution was made by the collective friction/damping, and I will check.

That is a good one to discuss with the group, that a collective pitch lever can become excited if the friction is too low and if the pilot grips it too tightly. If you notice that a vertical rotor vibration is starting, relax on the collective, to the point of letting go if necessary.

The collective friction is very important on most helicopters, not just for comfort. It serves as a damper to quell the PIO that can happen. That is also the reason for the friction collar on some Bell rotor heads. Very small helicopters are less likely to get into collective induced PIO because the natural vertical frequency of the airframe is higher than the frequency that a pilot's arm on the collective has. Big helicopters tend to have lower frequencies.

Regarding Lu, he simply cannot learn, and he is reading a design FAR paragraph as if it were a test paragraph. He is foolishly unable to listen - it simply proves yet agian how his stubbornness degrades the value he could add. I am sorry that I have caused all of us to scroll down past his drippings, where he thinks he has to re-post his entire last post again and again and again.

To: Nick Lappos and Grey Area

Nick Sez:

“Regarding Lu, he simply cannot learn, and he is reading a design FAR paragraph as if it were a test paragraph. He is foolishly unable to listen - it simply proves yet again how his stubbornness degrades the value he could add. I am sorry that I have caused all of us to scroll down past his drippings, where he thinks he has to re-post his entire last post again and again and again”.

Lu Responds:

In the CFR 14 document under Subpart A-General Paragraph 27.1 Applicability subparagraph (a) it states the following. This part prescribes airworthiness standards for the issue of type certificates, and changes to those certificates. For normal category rotorcraft with maximum weights of 6,000 pounds or less.

Paragraph (b) states: Each person who applies under part 21 for such a certificate or change must show compliance with applicable requirements of this part.

Lu Responds Further:

In the CFR 14 document under Subpart B-Flight, Paragraph 27.21 it states the following: Each requirement of this subpart must be met at each appropriate combination of weight and center of gravity within the range of loading conditions for which certification is requested. (My words) It implies that this can be done by flying the aircraft under the stated conditions of the sub paragraphs or by calculations based on, and equal in accuracy to the results of testing. With the advent of super computers Nick may be correct in stating that no (flight) test is required. That may be true at Sikorsky but not at Robinson and that is the topic we are addressing.

Grey Area may also be correct in stating that the advisory circular is just that as it is the compendium of experience gained over the last 25-30 years in the certification of Normal Category Rotorcraft as that is stated under paragraph (a) under Purpose. However under paragraph (5) Applicability it states the following: This material is not to be construed as having any legal status and must be treated accordingly. However, to ensure standardization in the certification process, these procedures should be considered during all rotorcraft type certification and supplemental type certification activities. (My words) However just about everything contained in AC-27 is contained in CFR-14 part 27 so the requirements of the testing must be complied with to include the test for out of trim and 90-degree sideslip. This means that at Robinson they had to demonstrate this capability in actual flight and not in a super computer which they did not possess at that time.

Someone please put Lu out of his misery.

Hello Gentleman!
Hope all had a merry christmas!!

To Bintang.´s post, about turning a R-22 into a Skycrane-TR!

First: I do a bit of checking out pilots for tunaboats, which entales some rather interesting maneuvering very close to the water. Unfortunatly it is not the low altidude and loss of reference on calm (mirrirlike) water that tends to "eat" pilots and helicopters in this case, but the rather severe bank-angles people like to get themselves into. I preach do not use more than 30° bank if low on the water. First it is rather difficult to maintain altidude while concentrating on the target and listening to an totally excited skipper yelling at everyone, second there is no need to bank so hard - just slow down and you turn in no time.
What I want to say is: Even if you want or have to use a sideways quickstop, don´t bank it more than 45° in this particular maneuver, as your rotortips come quite close to the ground.
I do not know who came up with the term quickstop (anyone know?), but it is rather irritating to students, as they want to do it "quick". The alternative "fast decelaration" is a cumbersom expresion I know.....
Students have to be trained to take it easy on the "quick", there is no hurry.
If you really have to stop in a moment (like someone running out in front of you...), let the helicopter climb a bit instead of slamming the tail in the ground......

Fly safe.

To Nick Lappos:
Merry Christmas! (if you celebrate it......)

One question only:

Do you fly or ever did fly Robinsons?
If yes, both or just one model?
What kind of flying was it (test, pleasure, work...)?

Ouups, that´s already three Questions......

3top,

Thank you, I do celebrate Christmas (you can tell by my credit card statements). Hope you had a nice one, too.

No, I have never had the oppurtunity to fly a Robbie. Of course, if some ppruner in the Connecticut area has one available........

Nick Lappos

Are YOU mad Nick!!!
Don't you read all those posts by Lu? Its a death trap for the unwary....
But seriously, If you make it up to Ontario, you I'd be happy to jump back into a R22 to let you have a pole.
All you have to do now is figure out a junket with Sikorsky so you can visit our operation as a consultant of some kind.......
P.S: Don't forget the AMEX - helo flying is expensive. :) :p ;):confused: :(
Note progression.....

If you ever are down in Vero Beach, come on down a little further to Ft. Lauderdale (Volar) ... I'd be glad to arrange something.

Nick and Lu,
I am trying hard to continue to respect the experience each of you has but its getting difficult. Soon I will have to ignore any set of posts that includes you. It would be a loss but lets face it, every subject on here is getting high-jacked.
If I could get a link to this infamous Georgia Tech report I would appreciate it, I was unable to locate it on their web site.
Both Sikorsky and Robinson products have their strengths and weaknesses, lets get past it.

Now on this topic:
I recently had a discussion with the rest of the training dept I work in about the sideward quickstop and how to approach the teaching of it. In our operations the only reason we could see for performing a quickstop is wire (or other obstacle) avoidance. The reason one would be in a position to have to worry about wires would then be because of low altitude, probably due to lousy weather.
The side-stop was recommended by some of us for the simple reason that instead of pointing the nose into a featureless sky, you are maintaining a good ground reference to assist in maintaing a/c control. If hitting the t/r is really a concern, then think about why you are there (low).
And yes, I do know that some jobs require low-level operations.

If you use a sideways quickstop in an attempt to avoid a wire strike, wouldn't you now risk running the tail rotor into the wire ( or catch it on part of the ship leading to a sort of dynamic roll over?

And bank angles vs pitch angles. I'm not sure exactly how much of a pitch up angle I have with a streight ahead quick stop but I don't think it's more than 15 degrees nose up(in bell 47).

Someone stated 30 bank should be the max for a sideways quickstop. Seems a little aggressive to me. Wouldn't you run into a risk of mast bumping that at the point of leveling the helicopter? Wouldn't this all so vary with the entry airspeed (say slightly above transitional to 50 mph max)?

Gentlemen,

Please do not forget that any agressive quickstop manoeuvre can induce vortex ring state especially at the end. If we are talking non military manoeuvres then for wire avoidance is not full collective plus pitch up to a zoom climb better than trying to fly a quickstop?