Aerobatic Maneuvers - Definition of

[albatross]

While reviewing the limitations section of the RFM of our beloved helicopter we find the limitation:

"Aerobatic maneuvers prohibited."

We all nodded sagely and agreed this is a good thing.

Then someone asked: "What combination of attitude, roll rate ect. would constitute aerobatics?"

We looked everywhere but could not find an exact definition except:


"According to the FAA (FAR §91.303), aerobatic flight is defined as “an intentional maneuver involving an abrupt change in an aircraft’s attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.”

Pretty vague I think.

Anyone have a better definition?

NO I am not advocating the performance of any aerobatic flight - just trying to define the threshold of what we would call aerobatics in a helicopter regardless of type or capability.

I think aerobatics are like pornography - it might be hard to define but you'll know it when you see it!:E

[rudestuff]

Apparently you're required to wear a parachute if you exceed 60 degrees of bank or +/- 30 degrees pitch, so that could be a guide. I'm sure most of us break that one daily...

[albatross]

Thanks for that.

I have heard that definition more than once and it seems widely accepted.

A reference to some FAA, CAA, CARS or ICAO "rule" would be nice.

I assume that for Bell and Sikorsky products either the company has a definition or the FAA does.

Perhaps Nick Lappos will have an answer.

Kind of like someone saying "No Speeding" and not telling you the speed limit or saying that "Speeding is driving the vehicle at an abnormal velocity."

[chuks]

for fixed-wing, yes, that is what we use, 30° in pitch and 60° in bank. A lot of the modern stuff has Bitching Betty saying "Bank angle, Bank angle..." if you go past 45° of bank, even, but that is for Part 25, Transport Category aircraft.

I seem to remember seeing something more than those limits when being given a hop in B-206s and B-212s but I could be mistaken in that. You could ask those topless Nigerian ladies in their dug-out canoes what they saw, I guess, if you take them for reliable witnesses.

[Phoinix]

We had the same question during our 135 T/R course in Donauworth:

Q: What is an aerobatic maneuver, how do we know how to avoid it?
A: You can do 90° of pitch or bank, and you won't exceed the limits...

That was it. No other reply was given no matter what.

[chuks]

You have certain G limits, positive and negative, that you can hold to while also putting your airframe into some pretty weird attitudes. The humble barrel roll is a perfect example of this, when you are inverted but with positive G if it's properly flown.

The thing is, though, it is the attitude that defines "aerobatics", not the G-loading. For instance, I can easily put my airplane up on a wing-tip without pulling much G, simply by not pulling much nose-up pitch, letting it descend at 1 G, but that would still be an aerobatic manoeuvre, legally speaking.

I think the regulators are worried about us getting something wrong, hence the limits to what attitudes we can put our aircraft into as the only easy thing to define. If we were only told not to exceed a G limit, well, I could barrel roll my Twin Otter and be alright with that so long as I made no mistakes. Get it just a little bit wrong though, when things can happen fast, and then I could easily bend or break it.

I was very interested to see a "buttonhook" flown in a B-212, something very like a wingover. I could see that it might easily turn into a tailslide in the hands of a clumsy pilot, when I suppose the helo would come apart.

[teeteringhead]

To inform the debate, the military definition is/was "manouevres exceeding 90 degrees in pitch or roll".

This was used for the (RAF) Gazelle displays in the 70s/80s, which got around the then accommpanying rule "aerobatic manouevres are prohibited in helicopters." :E

..... and then along came the Lynx .......

[Overdrive]

Fly past a crowd. If they clap and cheer, it's aerobatics.

[SHortshaft]

You answered your own question well when you quoted FARs as saying:
"According to the FAA (FAR §91.303), aerobatic flight is defined as “an intentional manoeuvre involving an abrupt change in an aircraft’s attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.”

Most countries will have a similar phrase in their documentation...and yes the starting point was probably an ICAO Annex.

Albatross, you are a big bird, surely it doesn’t take one of the wisest birds to explain to you what abnormal or abrupt feels like?

[albatross]

Thanks Shortshaft - Now I can log all my ILS approaches as Aerobatic time.

I was just trying to find a more definitive answer than the FAR gives.

OVERDRIVE - Great Answer - LOL.:ok:

[docstone]

Famously Bell are said to have added an FMS after a 407 performed a pretty impressive display at a South African airshow (video available to watch at the regular outlets - the commentator is a tad surprised).

As the proud new owner watched gleefully, sat alongside was the local Bell rep. As the display ended the rep turned to the owner and advised him the aircraft was good only now for scrap...and soon thereafter the FM supplement appeared banning aerobatics (although as this threads notes, the definitions are vague). Shame, since the airframe is more than strong enough.

[skadi]

I think, the statement ( aerobatics are prohibited ) in the FM has something to do with certification requirements?
Look into the FM of the famous BO 105, its also in there. But aerobatics are no problem with a skilled and well trained pilot ( p.e. Red Bull, German Army )

skadi

[FLY 7]

Presumably the 300C can be described as 'aerobatic'?

I've just been watching Dennis Kenyon's DVD, which features 'aerobatic displays' in his Hughes/Schweizer.

[Jack Plug]

I thin DK describes his routine as display, not aerobatic flying. Maybe he'll drop by this thread and let us know.

For me the onset of redout or brownout is a good starting point:ooh:. maybe not in the old R22 though.:eek:

[Brian Abraham]

From (Court ruling) http://www.ntsb.gov/alj/o_n_o/docs/AVIATION/3655.PDF

The FAA Administrator in his reply brief concedes that the regulation (FAR section 91.71(d) defines acrobatic flight as "...an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight.") does not define acrobatic flight in terms of specific degrees of pitch or banking, but asserts that such specificity is unnecessary and would be undesirable, given the wide variation in aircraft and their design capabilities.

Australia has much the same
Civil Aviation Regulation 2 acrobatic flight means manoeuvres intentionally performed by an aircraft involving an abrupt change in its attitude, an abnormal attitude, or an abnormal variation in speed.

but goes on to say
Civil Aviation Regulation 155 Acrobatic flight
(2) For the purposes of subregulation (1), straight and steady stalls or turns in which the angle of bank does not exceed 60 degrees shall be deemed not to be acrobatic flight.

[topendtorque]

The question is certainly a paradigm of sorts.

I have personnally witnessed the insides of transmissions, one of which was removed from a helicopter of the, "so called Famed" blue Eagles, which had been removed at 28, - THAT IS TWENTY EIGHT TOTAL HOURS FROM NEW.

On the tag was the reason.
- INTENSIVE FLYING-

Now I have to say that some of us took the mickey out of this little predicament quite some,I mean we flew 'em - an flew 'em - an' held our mouth, jess right, (well we thought so) an' we used words like 'tally ho' and bandits (cattle) at your 4 oclock, an' we wore RAYBANS and dramk beer like it was goin' out of fashion, - an swaggered around and none of our transmissions still had the blue on the gears after all'o'that, an we thought we had been misled.

So for the aerobatis team, the Blue Angels, just what is "AEROBATIC FLIGHT"?

[DennisK]

Hallo lads,

A thread quite dear to my heart.

Its a consideration ... I won't call it a problem ... that I have had to address for thirty-five years. I'm about to run through my One thousand, two hundred and thirteenth public display next month at London City Airport, so it is always important that the rules aren't bent. Insurance is also a major consideration.

As has been noted here, I refer to my air shows as 'display flying.' and being a DAE it is important that intending DAs understand the basics.

Having discussed the matter with the safety regulation guys at the display division of our CAA, the numbers that seem to be accepted are 'any manoeuver that doesn't exceed either 90 degrees in roll or 60 degrees in pitch.'

That seems reasonable to me. Of course the BK 105 and the Lynx manoeuvres leave that defintion for dead.

As to exessive changes in attitude, I'd like to think that my standard display routine stays well within the requirement there. I routinely place my pace notes on the seat alongside me and they do need to stay there throughout the sequence.

Out of interest, and before I finally quit the display scene, I plan to produce a display manual for DAEs. I just feel that the basics I have learnt over the years need to be formally set out somewhere.

As I have oft quoted here ... I dearly want to see some younger pilots come in to the display scene when my hat is finally put to bed.

Take care all and safe flying,

Dennis Kenyon.

[Sgtfrog]

Dennis,
great idea, would like to see something in paper about your exploits! Met you briefly at Redhill during Veeany's safety evening. have you thought about running some sort of course for budding display pilots?
SF:D

[chuks]

Where did I get that 60° in bank and 30° in pitch from, anyway? I know what the U.S. FARs say, and it is not there in so many numbers, no. This is some extra information defining an "abnormal attitude" but where exactly do those numbers come from? Perhaps they are in Part One, "Definitions", in the Airman's Information Manual, which I do not have here ready to hand. Or it might be one of those things that "everyone knows" that is not strictly correct.

This 90° in bank and 60° in pitch; is that specific to one pilot's display routine or is that the general UK CAA definition of the starting limits for an "abnormal attitude" where aerobatic flight begins?

[Rich Lee]

Several years ago (in the early 1980's) I wrote the following to discuss my views and opinions regarding ICAS policy and the ACE program as they apply to helicopter aerobatic flight. It may answer a few questions concerning the US FAA Aerobatic restriction.

REGULATIONS

In the U.S., the definition of aerobatic flight is contained within FAR Part 91, Subpart D - Special Flight Operations and says:
"No person may operate an aircraft in aerobatic flight-
(a) Over any congested area of a city, town, or settlement;
(b) Over an open air assembly of persons;
(c) Within a control zone or Federal airway;
(d) Below an altitude of 1,500 feet above the surface; or
(e) When flight visibility is less than three statue miles.

For the purposes of this section, aerobatic flight means
an intentional maneuver involving an abrupt change in an
aircraft's attitude, or abnormal acceleration, not necessary
for normal flight."

This rule applies to aircraft in general and does not distinguish between airplanes and helicopters.

Aerobatic flight is somewhat further defined by FAR Part 91.307 Parachutes and parachuting which states in part the following:
"(c) Unless each occupant of the aircraft is wearing an approved parachute, no pilot of a civil aircraft carrying any person (other than a crewmember) may execute any intentional maneuver that exceeds-
(1) A bank of 60 degrees relative to the horizon; or
(2) A nose-up or nose-down attitude of 30 degrees relative to the horizon."

Although aerobatic or acrobatic flight is not mentioned within this regulation, the FAA has interpreted flight beyond these limits as aerobatic. This regulation does not differentiate between airplanes and helicopters. It should be noted that few people who have successfully parachuted from an out of control helicopter.

These broad definitions are quantified for airplanes in the certification requirements of FAR Part 23-Airworthiness Standards: Normal, Utility, Acrobatic, and Commuter Category Airplanes, which states the following:

"FAR Part 23.3 Airplane categories.
(a) The normal category is limited to airplanes that have
a seating configuration, excluding pilot seats, of nine or
less, a maximum certified takeoff weight of 12,500 pounds
or less, and intended for non-acrobatic operation. Non-
acrobatic operation includes:
(1) Any maneuver incident
to normal flying;
(2) Stalls (except whip stalls); and
(3) Lazy eights, chandelles, and steep turns, in which
the angle of bank is not more than 600.

(b) The utility category is limited to airplanes that have
a seating configuration, excluding pilot seats, of nine or
less, a maximum takeoff of 12,500 pounds or less, and
intended for limited acrobatic operation. Airplanes
certified in the utility category may be used in any of the
operations covered under paragraph (a) of this section and
in limited acrobatic operations. Limited acrobatic operation includes:
(1) Spins (if approved for the particular type of
airplane); and
(2) Lazy eights, chandelles, and steep turns, in which
the angle of bank is more than 60 degrees.

(c) The acrobatic category is limited to airplanes that
have a seating configuration, excluding pilot seats, of
nine or less, a maximum certificated takeoff weight of
12,500 pounds or less, and intended for use without
restrictions, other than those shown to be necessary as a
result of required flight tests.

(d) The commuter category is limited to propeller-driven,
multiengine airplanes that have a seating configuration,
excluding pilot seats, of 19 or less, and a maximum
certificated takeoff weight of 19,000 pounds or less,
intended for nonacrobatic operation as described in
paragraph (a) of this section.

(e) Airplanes may be type certificated in more than one
category of this part if the requirements of each requested
category are met."

There is only a Normal category for US rotorcraft. There is no Utility or Aerobatic category. The rules do not exist to certify a helicopter in these categories even if they did exist. The US does allow Restricted category operations and the issuance of a Special Airworthiness for purposes that include Show/Exhibition. All helicopters in the US approved for aerobatic operations must do so with a Special Airworthiness certificate. The FAA will individually approve any intended maneuver for display and require that certain limitations and restrictions apply when those maneuvers are performed.

US helicopter certification requirements are contained in CAM 6 Rotorcraft Airworthiness: Normal Category (the old rules) or FAR Part 27 Airworthiness Standards: Normal Category Rotorcraft (the new rules) which 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. Acrobatic and utility categories are not directly addressed by either regulation. The subject is indirectly addressed in section 6.718, Types of operation, of CAM 6. This section states: "The type of operation to which a rotorcraft is limited shall be established on the basis of flight characteristics and the equipment installed". FAR Part 27 is even more indirect. The regulations pertaining to Flight Characteristics in FAR 27.141 General, and 27.143 Controllability and maneuverability limit operations to those within the limits of the helicopter and in 27.141 (b); "Be able to maintain any required flight condition and make a smooth transition from any flight condition to any other flight condition without exceptional piloting skill, alertness, or strength, and without danger of exceeding the limit load factor under any operating condition probable for the type..."

The only realistic definition of helicopter aerobatic maneuvers is contained within Chapter 49 Issue A Certificate of Waiver or Authorization: FAR Section 91.79 (Aviation Event) within Part 17 General Provisions B., (11) which states: "Helicopters may perform aerobatic maneuvers no closer than 1,000 feet horizontally from a spectator area. These maneuvers are described as a 90 degree pitch down, split "S", loop, and barrel roll. Performers proposing to use these maneuvers in an air show must produce evidence of approval by AFS-20."

The FAA took the position several years ago that unless specific aerobatic maneuvers were included in 'kinds of operation' and therefore tested as any other maneuver would be during certification testing leading to the issuance of a type certificate, then those 'kinds of operation' were not authorized. There is nothing to prevent any manufacturer from including any aerobatic maneuver in the application for certification, testing to prove that aerobatic maneuver can be performed safely, and then listing those maneuvers as 'approved kinds of operation'. This is not an unreasonable expectation today, but did not exist in the early days of rotorcraft certification. In those days, if you could do something within the limitations and restrictions of the aircraft, it was not prohibited.

Older US helicopters did not have an aerobatic maneuver restriction in the flight manual. The H300 and H500 are examples. Both have performed numerous fully aerobatic displays (by any definition) within the limitations specified in the type certificate. In the 1980's the FAA realized that many of these maneuver had not been tested as part of certification testing and instructed the manufacturer to 'insert' the prohibition against aerobatic maneuvers in the limitation section of the flight manual. I will not go into the details of the negotiations that took place but the end result is that Hughes/MDHI reluctantly complied with the FAA request.

As a side note, a few years later MDHI decided to certify the MD500 NOTAR as aerobatic for loops, rolls, split-s, hammerheads and a few other maneuvers. A flight strained aircraft performed all those maneuvers within expected performance limitations. The FAA regulatory process could not handle the request in a timely manner so MDHI withdrew the request so as to not delay certification.

The answer to your question is that some helicopters cannot perform aerobatic maneuvers safely and have a prohibition for that reason. Others are prohibited because manufacturers do not want to incur the additional cost of certification or because the FAA does not - until this day - have a aerobatic category for helicopters. Hope this answers some of your questions.

[Overdrive]

An interesting post Mr. Lee :ok:

[DennisK]

A lot to take on board Mr Lee, but certainly comprehensively addresses the issue.

BUT. If 60 degrees of bank is a limit, how do we legally teach the 'Max Rate' turn at around 65 to 70 degree bank angle? An exercise which I feel offers scope for advanced handling appreciation to suitably aware student pilots.

To answer the Display Manual item ... I am already up to display manoeuvre No 7 out of the total of 17 I have available.

But offering a display course ... that's a different ketle of fish and I'm not at all sure of the legality of that! I have raised the matter with GAD display staff and in essence they are supportive, but only once they have examined my proposed manual.

The next problem is charge ... what would a prospective DA expect to pay for say ... a ten hour course over a four/five day period?

In fact I am currently teaching my very first pilot (ex Pitts fixed wing) and to be honest, I'm using her to learn as I go along!

All input more than welcomed.

Take care all,

Dennis Kenyon.

[topendtorque]

Me thinks that this thread could become the most informative for newbies ever.

There is no doubt that many of us have evolved maneuvres which are exciting to watch and intricate to perform. They often need close attention to detail to be safe.

We should first think about what our POH tells us, I.E. how fast from stop to stop on the cyclic is allowed, Power limitations, rearward or sideways flight airspeeds, etc.

If one is never outside the POH then one must be assumed as never to be performing 'aerobatic' maneuvres? Perhaps.

One might be performing for an "airshow", or as an handling "display", but never cross the threshhold of acceptable maneuvres from within the POH when the type was certified.

One might manipulate the helicopter in a variety of 'displays routines' none of which engender approach upon the POH parameters.

I do not believe that the subject of 'Aerobatic flight' (for helicopters - rigid head included) need be worried about by administrations such as FAA or others, as one must contain oneself within the POH.

In the F/W world I think more definition is required. An A/C that is cleared for aerobatic flight would have +, -, G limitations beyond the utility catergory.
But to pilot that aircarft toward those limitations one must require endorsement, - in aerobatic maneuvres.???

After all there is no way that we could do a lomchevak or a flick roll in a thing with rotating blades.

I must amend and beg your pardon here, I have been witness to a flick roll in a R22, I still say that it should not be a permissible maneuvre.
tet

[Backward Blade]

Someone should contact the "Red Bull" display pilots, as I believe that those 2 drivers have/invented the aerobatic display certification on their licences (civilian) with the FAA and European agencies and only those gentlemen and only those 2 machines. As for the Military well that would be a whole different kettle of fish would it not

[Bravo73]

Just in case you haven't seen what the Redbull gents get up to:

http://www.youtube.com/watch?v=RGu45s1_QPU

http://www.mtorque.co.uk/ubbthreads/images/graemlins/default/bowdown.gif

[DennisK]

The fabulous displays produced by the Red Bull team are surefire 'aerobatic' manoeuvres and well within the capabilities of the solid rotor head system ... indeed I was first treated to the display possibilities of the type, by Charlie Zimmerman and Herman Fuchs at Cranfield during the 1986 World Championship event, which Fuchs won. Charlie had won the previous two events.

Earlier in 1975 I flew with Zig Hoffman, again on the BO 105 when he performed the first full loop I had ever seen. It was largely due to him and his tuition, that I was able to develop a watered down display version on the Enstrom Shark at the 1978 Farnborough event.

Today however, I occasionally have mixed feelings when displaying various types. Over the years, I've had some highly experienced guys approach me suggesting that such flying isn't in the best interests of our industry, bringing with it a 'swashbuckling' element, hence my reluctance today to set up some kind of display tuition programme.

Overall I take the view that providing the required level of handling skill is present and the prospective DA has the right motivation, such flying does bring extra interest to the exciting world of rotary flying ... but I'm always listening for alternative views.

We've had a few heli display fatalities and I never want to see any more.

How do other pruners see the situation?

Safe flying to all,

Dennis Kenyon.

[Rich Lee]

BUT. If 60 degrees of bank is a limit, how do we legally teach the 'Max Rate' turn at around 65 to 70 degree bank angle? An exercise which I feel offers scope for advanced handling appreciation to suitably aware student pilots.

The FAA has been using the old Chapter 49 definitions. A 90 degree pitch down (or up or roll), split "S", loop, and barrel roll as helicopter aerobatic guidance in the absence of any flight manual maneuver limitations. A bank greater than 60 degrees would not be considered aerobatic by the FAA. Nor would a quick stop with a pitch-up of 60 degrees.

There has been a tendency by the FAA to use a 'reasonability' criteria. If something is considered a reasonable helicopter operation, like a quick stop or flare in autorotation, or max rate turn about a point; then it is an intentional maneuver required for 'normal' flight that does not require 'abrupt' changes in aircraft attitude.

As an experienced display pilot you know when a something is an 'intentional maneuver involving an abrupt change in an aircraft's attitude, or abnormal acceleration, not necessary for normal flight' and what isn't. Manuevers like loops, rolls, in-plane veritical 360 degree pedal turns can be performed without abrupt changes in attitudes, but are not necessary for normal flight. A quick stop may be necessary but when performed with a too abrupt change in aircraft attitude it borders on the aerobatic. One can quibble with exact rates and attitudes but we all know when a maneuver is taken to an extreme and when it is considered normal.

Though I do not have knowledge of every pilot action taken by the FAA for aerobatic flight in helicopters, I very much doubt that any pilot would ever be violated, or an aircraft grounded for inspection, because of a max rate turn at up to 90 degrees of bank as long as there was no maneuver limitation or restriction prohibiting the maneuver in the Rotorcraft manual.

Backward Blade

I am aware of the circumstances with which the Red Bull pilot and aircraft are certificated for public display in the US; and can state with certainty that Red Bull, the FAA and the International Council of Airshows worked cooperatively to mitigate risk and protect the public in accordance with all existing regulations. Listing everything the Red Bull team was required to do, and the things the Red Bull team decided they should do would be difficult here as the lists are very exhaustive; but to my knowledge the entire operation is being conducted with the upmost professionalism.

[Backward Blade]

Sir, by the form and content of your writing I will no doubt defer to you. I was by no means questioning Red Bull's qualifications. I was merely refering to something that tickled my memory regarding their civilian certification with regards to aerobatics and helicopters...maybe there would be some lingo in any-one of those "paperwork aerobatics" that you were refering to. No offence or ignorant charge was meant.

Fly Safe
BWB

[ShyTorque]

Interesting subject.

I was chosen to display the RAF Puma in the late 1980s. The display we came up with was seen as "adventurous" and in truth it did stretch the aircraft to its limits. The pilot's manual said aerobatic manoeuvres were prohibited, without giving any further guidance on a definition. I took that to mean no more than 90 degrees of pitch or roll.

The RAF procedure was for the incumbent display pilot to come up with a workable display and for it to be approved first at unit level, then by the station commander, then by the Air Officer Commanding. My display was approved without modification and flown successfully. We had a good, safe season and the display was appreciated by those who saw it.

However, after I moved on, permission for the display was later withdrawn following a tail rotor incident. Permission for a display including similar manoeuvres was re-instated in the early 90s, but another tail rotor incident occurred and as far as I am aware, it has never been flown since.

"lsh", who some times posts here, might have some more info as he was the crewman involved after my time.

[Buster30]

Dennis,

I have seen the videos of the red bull Bo105 and your Display routines. I think they are all stunning to see. Keep the dream alive:D.

Its marvelous that you are considering passing those skills on.

Kind regards

Busta

[Rich Lee]

Backward Blade Your post created no offence nor was it without merit. The rules are different around the world and I know nothing of what certification or approval steps that Red Bull has taken outside of the US. I merely wanted those interested to know that Red Bull went to great engineering lengths to prove to the FAA they could do their routines safely and the US pilot, Chuck Aaron, approached his training and conducts his flights in a manner that is most professional.

Great controversy surrounds the issue of aerobatics in helicopters and discussion that question when, where, how, and under what authority these maneuvers are conducted are always of considerable merit. Please accept my apology if my reply to you seemed as if I was offended.

[Backward Blade]

Somehow methinks that we were somehow trying to say the same thing. Anyways it is fun to watch, but me and my 7 ratings in however many varients will NOT be attempting any such thing, nor would I live much longer if my wife found me trying to do so. I usually find that a firm fear of god, (name your flavour) or of the engineers of the AS350 hydraulic system, combined with the even more firm belief that my tailboom and mast should stay attached at all times...to be the best descriptor/identifier of an aerobatic maneuver. But that's just me. Fly safe all. There are many out there that DON"T do what we do, in what-ever form it may take, that often think we aren't safe. Their loss. Great conversation.

BWB

[topendtorque]

I checked out the red bull site and saw some consistancy the below statement.

you know when a something is an 'intentional maneuver involving an abrupt change in an aircraft's attitude, or abnormal acceleration, not necessary for normal flight' and what isn't.

Particularly at the recovery from inverted flight on at least two occasions, I noticed quite a bit of, what looked like, "now which way from here?"

My dearly departed dear old dad, who I had the pleasure of checking out in the '47 and who used to fly around as many of our dear old dad's did, for purposes of aggression years ago, told me that a good flying display was,
1. Unpredictable,
2 Always precise,and
3, Forever safe.

Somehow the red bull display, on the video clip, was wanting at least in the first two of those regards.

I also have a question for DennisK,

I read somewhere some time ago, after whatching one of your videos that the aerobatic championships had a list of acceptable maneuvres, for want of a better description.

How do they arrive at those maneuvres? Say someone comes along with a new one, do they, for instance discuss with the applicant, how he might recover in the event of engine failure ? Or might he be allowed to include any maneuvre without discussion, in his freestyle element.

This could be conter-productive as many if not all of the judges may not have a shmick of the maneuvre, or its safety or complexity beforehand. Let alone the pilots skill or knowledge.
Therefore they would be ill equipped to judge it.

Having done gymastics at a reasonable competitive level as a juvenile, I am well familiar with - set routines which lay down maneuvres of a usually fairly moderate difficulty level - and feestyle routines which are expected to encompass maneuvres of a higher difficulty level.

all of which have to be completed with the correct finnesse, that is if you wish to finish in the finals of course.
cheers tet

[Rich Lee]

My dearly departed dear old dad, who I had the pleasure of checking out in the '47 and who used to fly around as many of our dear old dad's did, for purposes of aggression years ago, told me that a good flying display was,
1. Unpredictable,
2 Always precise,and
3, Forever safe.

I assume your dearly departed dear old dad meant 'predictable' rather than 'unpredictable'; and if that was his intention I am in agreement. I would also add a few other things to his list.

There are many aerobatic helicopter clips floating around the internet. Some are of actual displays and others are of practices and some are just plain reckless maneuvering.

There are also many types of aerobatic displays. Not intending to be a complete list, there are competition displays, show displays, competitive evaluation displays, military displays, and manufacturers displays. Each type of display has different rules and objectives. For instance, a show display is intended to entertain and the appearance of unpredictability is part of that thrill of a show display. Competition display requires the ability to do what you say you will do in the time you have to do it in accordance with a set of agreed upon rules. Precision is an important part of the competition process.

Display pilots do have days when they fly better than others. Small things can have unpredictable consequences in a set routine. A wind shift or sudden downdraft, a bird, a problem with your aircraft, or an ATC distraction. All can cause a pilot to fly a display with less precision than he or she would like. Display pilots learning a routine usually do so at a safe altitude and as they become more confident and precise they bring their aerobatic safety floors lower and lower. I have trained many pilots to perform aerobatics in helicopters and few are perfect when first learning aerobatic maneuvers or when perfecting a display. You need a lot of altitude to recover from an aborted roll that has pitch-coupled. When a helicopter departs controlled flight (and they do from time to time) during a badly executed loop it is good to have a little altitude between you and terra firma.

Regardless the type of display, there are always critics who would prefer one over another. Many will see a practice display of aerobatic maneuvers requiring great skill and ability and find fault with what they see. There will always be those who make judgments as to what they like and what they don't. They are always right of course. Who better to judge what you like better than yourself?

When choreographing displays I find it more useful to ask spectators what they didn't like about a routine rather than what they did like. I am sure the Red Bull team display (European or US?) would benefit from your candid opinion. Why not drop them a line and tell them what part of their display you found wanting?

[topendtorque]

I assume your dearly departed dear old dad meant 'predictable' rather than 'unpredictable'; and if that was his intention I am in agreement. I would also add a few other things to his list.



sorry, wrong.

if you wish to scale in the boring part, then go predictable.

to demonstrate with the extreme, I remember watching a '269 doing a handling display of a spraying exercises at an airshow, once for about fiteen minutes, jeeeesus. The next day he didn't even show, even though scheduled, talk about boring, and predictable.

I would also say that some of the most awesome and exciting F/W aero displays that I have seen had sequences that were totally unpredicted.


When a helicopter departs controlled flight (and they do from time to time) during a badly executed loop it is good to have a little altitude between you and terra firma.



Yes we have had this conversation from to time, on different aspects, However I suggest that the saguine and predictable long slow zoom upward to a roll which then departs from precision control, which possibly has been practised many times, is hard to explain.

Why not drop them a line and tell them what part of their display you found wanting?

sure, when I get a second or two I shall, no doubt they will be well forewarned.

I have trained many pilots to perform aerobatics in helicopters and few are perfect when first learning aerobatic maneuvers or when perfecting a display.

In the vein of the thread, could you describe the maneuvres, that fit the word aerobatic?

We have all been having some problems with it.

Thankyou.
tet

[NickLappos]

Predictable is in the eye of the beholder, but the aerobatic PILOT who cannot predict the next maneuver is already dead, he just doesn't know it.

I flew an aerobatic routine in the Paris Air Show once, and in the 20 or so times I flew it (practice at the show, qualification trials with show officials, and in front of the crowd) I was never more than 1 second off in a 3 minute and 11 second routine.

To support Rich Lee (who has done far more than his share of this silliness) if the pilot is not flying a rigidly practiced routine, he is in vast trouble. The Crowd should find him unpredictable, but his CP had better not.

Regarding the qualification and certification, the FAA requires a "Certificate of Aerobatic Competency" that is issued by one of their examiners, not an easy certificate to earn, since the examoner puts his or her reputation in your pocket when you fly. I carried around one of these for several years while flying various models in airshows. I know the US Red Bull pilot, he is a real pro, and nothing he does is without cool professional, predictable deliberation.

The FAA also requires specific approval for each demonstration before a crowd.

[topendtorque]

The Crowd should find him unpredictable, but his CP had better not.


Thanks Nick
That is exactly what I meant. The display should be unpredictable, but the routine as you say, must obviously be well rehearsed.

[Rich Lee]

In the vein of the thread, could you describe the maneuvres, that fit the word aerobatic?

My original response had more to do with the history of the aerobatic regulatory process in the US. In that response the description of a helicopter aerobatic maneuvre is implied by the old Chapter 49. Simply stated, the US FAA considers anything over 90 degrees in pitch or roll in a helicopter to be aerobatic. It prohibits, without approval, any maneuvre not approved by the flight manual or considered to be a classic helicopter maneuvre as contained in the curriculum of most flight schools; and/or anything limited or restricted by the flight manual.

Examples of helicopter maneuvres most authorities, military or civil, consider to be aerobatic are loops, rolls, split-s, hammerheads, 90-90 rapid roll reversals, Waddington flips, Jacques flops, DK's 360 pedal turns in the vertical plan, vertical pitch downs to 90 degrees with or without rolls, inverted flat spins, Lomcevaks, Susie's nightmare and several others - alone and in combination with the others. All of been conducted, with approval, at public displays around the world in all types of helicopters.

To provide further example, at Farnborough, the thrilling (at least for me) military display of the CH-47 display is not considered aerobatic because the aircraft does not exceed 90 degrees of pitch or roll. The AH-64D display is considered aerobatic because it frequently exceeds 90 degrees of pitch and roll. The CH-47 is allowed to fly to a lower floor and is allowed closer to the show line while the Apache must use the aerobatic floor and show line.

30 years ago helicopter aerobatics at public display was new and the interpretation of helicopter aerobatics at different airshows around the world varied considerably. Now, there are few differences in interpretation between Paris, Singapore, Dubai, Lima, FIDEA, Farnborough, or other airshows large and small.

sorry, wrong.

if you wish to scale in the boring part, then go predictable.


A display routine may look 'unpredictable' to the crowd below, but outside of practice or training, the execution of the routine should always be 'predictable'. One of the primary considerations in the qualification of a display pilot at any international airshow is predictability. A pilot whose execution of his or her display routine is 'unpredictable' will not qualify and will not be allowed to display.

[Backward Blade]

I think Nick and Rich hit the nail on the head. Finally a couple straight answers from those in the "Know". Should the rest of us need a more in depth discussion I would recomend you start taking lessons! But Rich, and I ask this with the greatest amount of respect...with regards to all the maneuvers you mentioned having been performed in all types of machines...WHO the hell was the balsy bastard that did a loop, roll, or split S in a 206 outside of combat LOL? And if the poor bastard that had to do it at that time tell's me so, I don't think I'm one to disagree with him, at least on a keypad! T

Thanks for the clarification boys

Fly Safe all

BWB

[[email protected]]

One element that was alluded to regarding FW aeros is that an aircraft would have published 'g' limits that should not be exceeded when performing such manoeuvres. Which helicopters have published 'g' limits? Which helicopters are fitted with 'g' meters to monitor the fatigue on the aircraft when performing aerobatic manoeuvres?

I was lucky enough to fly all the Lynx display manoeuvres and the aircraft was limited to a max of 2.7 'g' IIRC and fitted with a 'g' meter. All manoeuvres were recorded in the F700 and the fatigue penalty calculated and applied - thus reducing the life of the components.

I think the 18 hour gearbox that TET refers to may well have been before the 'g' limits were applied.

Does the rest of the helicopter aerobatic world follow similar procedures and if not, why not?

In a FW, 'g' has predictable, calculable effects on the designed life of the airframe - the structure itself is pretty straightforward.

On a helo we have TRGBs and IRGBs on the end of long moment arms which were never designed with aerobatic stresses in mind and engines and MRGBs that were certainly never expected to be rolled upside-down.

The ability of rotor systems to produce massive accelerations in pitch and roll, thus enabling many of these manoeuvres to be flown without chopping tails off would appear to have outstripped the capability of the rest of the airframe to absorb said accelerations.

Having just watched the Red Bull video, the pilot is flying extremely gently in an effort to avoid generating high 'g' and his rolls are beautifully smooth, thus minimising twist on the tail boom. He modifies his recoveries from the wingovers/pedal turns etc to avoid having to pull through the vertical on the recovery, preferring to roll to a nearer horizon and then recover - again minimising the 'g'. There is certainly nothing wacky or dangerous in that display - very nice job:)

[Rich Lee]

Backward Blade I didn't mean to imply that 'all' of the maneuvres I listed have been performed in every helicopter out there, only that I have witnessed, have seen on film, or have heard of people doing something that might be considered aero in just about every helicopter that has been built. Some have even managed to do so successfully. I have seen skewed loops in a B206 and an R-22. I happen to consider loops in those aircraft to be extremely dangerous because if the slightest mistake is made then the outcome is likely to be fatal.

[email protected] I could not agree with you more. Without a recording G meter one has very little ability to determine if the G limits of the helicopter are being maintained.

I am often asked why Boeing performs the same routine in the Apache at every airshow. The reason is that aerobatic envelope expansion was conducted at mission gross weights to 7K Hd in an aircraft that was fully flight strained. We also did abort maneuvres such as an inverted pull through at high G from a pitch coupled roll which, as you well know, can involve some unusually high G. We know that those maneuvres and the maneuvres necessary to recover the aircraft if they go wrong, can be safely performed within all aircraft limits. We also know that they cause only a very slight reduction in the calculated lives of certain components. We don't do other maneuvres because I have no way of knowing with certainty that there are no detrimental affects to component lives unless we do another flight strain and that is very expensive.

Helicopters that are specially certificated to perform maneuvres beyond their certificated envelope are required to have a G meter installed. Further the FAA is beginning to require at the very least a vigorous engineering analysis of the proposed maneuvers for the very reasons you espouse. Many designs can do these maneuvres without coming apart in flight, but the real problem then becomes how much reduction in time-life components should be applied since these maneuvres haven't been applied to normal SN curves.

[JohnDixson]

Rich Lee's comments are right on target and hopefully will be read by all those flying acrobatic-like manuevers.

Particularly poignant are his observations about the Apache demonstration manuevers having been accomplished first in an instrumented aircraft so that the associated flight loads could be determined, in such a way that subsequent fatigue damage ( if any ) could be tracked.

At Sikorsky, we did exactly the same thing for the S-67 aircraft, which had an "approved" acrobatic envelope. ( Approval arising from an internal assessment from structural flight test management within the company ). The S-76 program that Nick Lappos referred to was similarly covered.

A couple of observations on this subject, arising from personal familiarity with the various related programs at Sikorsky:

1. A "G" meter is of some assistance for an acrobatic helicopter, but is not the limiting factor by any means in many cases. That is because the static strength of the fuselage and aerodynamic appurtenances such as stabilizer/stabilator is not so much the issue as much as rotor stall related loads. For example, the same 3.0 "G" snap turn at sea level will produce much lower rotating control loads than when attempted at Hd=10K ft*. Same comment applies to the same manuever performed at a very light weight versus at a maximum permitted weight. Simply stated, rotating control loads are not linearly related to "G" alone. We found, in addition, that other factors, such as the collective position at the manuever entry point, influenced control loads for a "same "G, same weight, same Hd" manuever; the higher the collective at the cyclic pull point, the higher the control loads.

* In fact, control load behavior at altitude can exhibit other unexpected anomalies. The CH-53A aircraft had a Cruise Guide system, which was an indicator tied to an LVDT ( Linear Variable Differential Transducer ) embedded a the main rotor servo, i.e., it measured main rotor servo loads. At sea level and up thru the lower altitude/weight combinations covered by the original CH-53 qualification testing, the cruise guide load data agreed excellently with the rest of the rotation component loads and was a terrific leading indication of stall and high control loads. But when the USAF HH-53C arrived on the scene, with bigger engines and a higher gross weight/altitude operating spectrum, the main rotor control load behavior changed dramatically at the stall point, the main rotor servo load frequency signature changed, the peak main rotor servo loads flattened out, while the push rod loads were going up exponentially. Cockpit vibration cues did not provide a clue as to what was occurring. The point is that helicopter control loads associated with flight seemingly within the flight envelope is a complex subject.

2. Other control loads beyond main rotor stall related loads need to be known. Just one example: tail rotor bending stresses related to the gyroscopically induced loads during rolling manuevers are, typically for at least the SA tail rotor configurations, higher in left high roll rate manuevers than in high right roll rate manuevers. These loads can be high enough to be a candidate for manuever cycle counting and component life adjustment, if one plans on doing the manuevers on a repetitive basis.

I believe that the point Rich Lee referred to, and that I would heartily agree with, is that, for any helicopter, if an operator is intending to perform manuevers outside the normal, a consultation with the manufacturer to determine and confirm that these manuevers are covered by the flight test qualification program, and what the ramification with regard to component replacement times might be, ought to be priority one.

Thanks,
John Dixson

[topendtorque]

Thankyou to you test driver gurus for shedding some light on the definition of helicopter aeros.

I think you may be some distance from my original question though, when one filters through your 'high tech' talk and then mentally trangresses back to Dennis K's pedal turn in fixed vertical plane in an 'old tech' H269 for example.

Where does this leave the aspiring enthusiast who is wishing to learn?

I guess the thread became a bit discordant at one stage, and I apologize for my part in that with my choice of language being, "sorry wrong", when in fact it should have been, 'sorry I disagree'.

We certainly don't need to go over the ground again of who needs to demonstrate to whom the unpredicability, for demonstrations, of any sort to succeed as judged by the public.

And I disagree that any demonstration, be it military salesman ship or country airshow, is for any thing other than the very common reason to impress, regardless of the type of organised audience. That must be plain, surely.

BTW those machines that have attempted lamchevacks , esp in close proximity to the ground, sometimes 'kick awhile' before they become still.

In a couple of dreadful situations, so have their occupants, of which I have been aware of at close quarters.

For the sake of newbies lets disendorse the encylcopedia of F/W aeros from any fanciful notions that they may have.

A simple rule could be - never get a situation where your fuel load may not be flying in close formation with you fuel tank exit point. That should insure that oneis never close to the dreaded mast bumping weightlessness etc.

machines that can fly inverted by design surely must have been acquanted with fuel systems that can handle that.

[Rich Lee]

topendtorqueI think you may be some distance from my original question though, when one filters through your 'high tech' talk and then mentally trangresses back to Dennis K's pedal turn in fixed vertical plane in an 'old tech' H269 for example.

Where does this leave the aspiring enthusiast who is wishing to learn?


Go to Russia, get your hands on a Mil MI-34S Hermit and an instructor with helicopter aerobatics qualifications, and then enjoy the pleasure of flying a purpose built aerobatic helicopter. Or ...... just watch the video

http://www.madskies.com/tag/aerobatic/

[topendtorque]

Thanks, Rich, I had a look. A bit out of my league, I don't have one of those Elton John / Corey / Lleyton back to front cancer caps in my cupboard, and don't fancy wearing one either. That is if that is what it takes to swan one of those machines around like a drunk sailor.

I do say though the machine itself looks quite impressive.

[DennisK]

A big thanks to the many guys who are contributing to the post.

I'd have to say that I have been far from aware of the goodly number of pilots who have knowledge of the display manoeuvres being employed ... and it is especially good to see input from guys like Nick Lappos.

In the case of the Enstrom Shark, the display sequence I worked up for the 1970s Farnborough shows was passed to me by the one time factory test pilots, being Mike Meger and Mott Stanchfield, both displayed the 280C at the 1973 & 1974 events. In fact it was in 1973, that I crewed for Mike Meger when he took first place in the second ever world heli championships 'freestyle' event at Middle Wallop, England.

My display routine was more than thoroughly investigated by the engineering division at the Enstrom plant in Menominee. The Chief designers, Herb Mosely and Paul Schultz went through each manoeuvre before giving me clearance. In those days there was no CAA involvement and the DA didn't exist. I flew a dozen displays with tell-tale equipment fitted to the M/R hub and max rotor disc defelection measurement ... all proved acceptable and the display I'm performing in 2008 are identical to the 1970s sequence.

I have 17 set manoeuvres where each have a 'gate' speed and height. The two are interchangeable for operating conditions. And yes, I have flown the sequence with a 'G' meter AND a rearward reading ASI. The manoeuvres to be flown for any given display are set out based on the display location, atmospheric conditions and the time slot requested.

I'm approaching my 1214th public display at the London City Airport event next month so I regard the display as well established. I take note of the variant views on such flying, but in the same way a violinists, a showjumper, a singer or all the other areas where the participant is pleasing the spectator, I feel rotary displays are a worthwhile part of our industry. Motivation? Just as written, but I have to add, the immense personal satisfaction of performing well for the air show crowd. (then there is the money!)

To answer 'Top End Torque' (something I never achieve in display work) the set manoeuvres you refer to were laid down by the FIA for the 1986 world champs event. Rather like ice dancing, competitors were offered a selection of manoeuvres are varying difficulty, but each carrying correspondingly more marks. In theory a display pilot could win the event using a constant hover! But it would have to be a good one!

I have taken part in the subsequent 1992, 2002 and 2005 world champ events and haven't seen the 1986 system used since. Now a 500 metre box with a 500 ft max height is provided in which the display pilot flies his preferred 'freestyle' manoeuvres in a strictly set time of 180 seconds, so every manoeuvre needs to score!

Display flying is obviously something very dear to my heart, especially as AD is catching up all too quickly and I'm fascinated to read ppruners posts. I'm also hoping to display either the Enstrom 480T or the Schweizer in Utah in a couple of weeks time.

This year, the champs are to be held in Germany, near Leipzig. I'll be there and would love to get a place as the oldest pilot to win something in a world championship event. Seventy-Six and counting!

Safe and good flying to you all.

Dennis Kenyon.

[topendtorque]

Dennis
check your pm's, I'll chuck you through a maneuvre for you to run your mind over.
tet.

[Rich Lee]

I have very much enjoyed the posts from crab, John, Nick and others; but Dennis, it's about time you wrote a book, isn't it?:ok:

[[email protected]]

I agree Rich, it would be very popular with rotorheads all round the world.

Out of interest - is Dennis our oldest (still flying) contributor on this forum? The thought of still being able to fly in one's 70's seems quite incredible. Nice one Dennis:ok:

[DennisK]

Now ... now - out there. I'm only old in calendar years. The spirit is still very much alive and throbbing! I've a way to go to catch up with the immortal Bob Hoover.

I did a book a few years back. Just a helicopter yarn flyers might enjoy. "Appointment on Lake Michigan" .... available from Amazon or www.electrocution.com. Phil Croucher's business.

I am working on a 'Display Manual' where I am setting out my display manoeuves and the associated handling. Not sure where its market will be, but I'm hoping it will at least lay down some basics for future display pilots. The difficulty is that display flying is very type sensitive so I can only cover the types I have displayed. Just the Enstrom 280/280c and 480 Turbine, the Schweizer 269 series, MD 500 series and the Westland Scout.

Others out there have similar or more experience on the more sophisticated types, so perhaps my manual could be the starter page for those interested.

Best wishes to all out there and safe flying lads,

Dennis Kenyon.

[Overdrive]

Out of interest Dennis, how many successful display pilots have arrived via a direct/deliberate path? That is to say, set out with display and aerobatic flying as their goal, as opposed to a development from initially a certain length of more regular commercial flying maybe?

It guess many are from a military or manufacturer testing background (understandably), but are there many of the top guys that came effectively from a PPL and straight into aerobatic training? I understand the relatively small world that it is, and the considerable costs early on... but has it been done by many?

Just the Enstrom 280/280c and 480 Turbine, the Schweizer 269 series, MD 500 series and the Westland Scout.


"Just"! Which is/was your favourite, and the most inherently natural for display work, as supplied, in an overall sense?

[birrddog]

For what it's worth, I believe Starlight Aviation in Cape Town, South Africa has a Test Pilot training course where they teach aerobatic maneuvers in a 105.

I don't know if it would be a suitable training forum for budding display pilots, but worth checking out.