PPRuNe Forums - View Single Post - MAX’s Return Delayed by FAA Reevaluation of 737 Safety Procedures
Old 4th Dec 2019, 04:01
  #4249 (permalink)  
Join Date: Nov 2015
Location: Bay Area, CA
Posts: 65
Originally Posted by n5296s View Post
@wonkazoo: seriously off thread and should be moved somewhere else. But these definitions are very different from what I have been taught. In fact if I used the terms like this my acro instructor (significant figure in local IAC etc etc) would disown me. Here is what I have been taught (and I believe is the terminology used by IAC):

-- aileron roll: what you have described as a barrel roll. Coordinated, positive G and neutral elevator throughout. Can keep a glass of water on the glareshield if you're Bob Hoover. Must be done fairly quickly (generally at the aircraft's maximum roll rate unless it's an Extra) to keep the nose drop under control.
-- slow roll: what you have described as an aileron roll. Totally uncoordinated, nose kept on a point by carefully synchronised use of all three controls. Highly vomit-provoking. Can be done as slowly as you want, the extreme case being a rolling turn.
-- barrel roll: combined loop and roll, performed similarly to an aileron roll but with up elevator throughout. Not afaik used in competition, but fun to do around appropriately sized puffy cumulus.
-- bunt: very much a British-English term for exactly what you describe. A pushover in US English.

I often see the term "barrel roll" used to describe what I would call an "aileron roll". If I inadvertently hold back stick while performing a roll, I get told "you barrelled that". Maybe the UK terminology is different, I've never flown acro (or indeed aeros) in the UK. (Just like I learned to ski in French, it was years before I could talk about skiing in English).
I'm sorry, but your definitions and use are somewhat innacurate or outright wrong. Perhaps as you say a cultural gap, but I own Neil WIlliams' book so I am aware of the terminology in the UK. To your suggestion that I am not familiar with the IAC. If you like I can take a photo of the large box of IAC trophies and plaques I have won in the unlimited category, or maybe I'll just take an image of the CA Points Series Second Place I won in 97 or so.

You are correct- Barrel Rolls are not a recognized figure in either the FAI or IAC. If you want to parse this to the nth degree it isn't a recognized aerobatic figure in any competition series I am aware of. (Nor did I suggest it was.) As to a loop and a roll or something like that it's just not true. There is a figure that I have seen historically called a barrel roll that ends up with the airplane on a heading 90 degrees from the original heading, but this is not a modern day description, at least here in the US. Your suggestion that readers should look up Bob Hoover Barrel Roll while pouring water is a good one.

Aileron rolls are notslow rolls by any definition, in fact in a modern day aerobatic monoplane or biplane the roll rate is in the neighborhood of 400 degrees+ per second. (An aileron roll is a recognized figure in the FAI catalog.) Suggesting that they are slow is bonkers. Yes, two point or four point rolls slow it down a bit in overall time, but the roll rate remains the same. Rolls can be added to a turning circle or a 45 upline or a vertical up or downline or the top or bottom of a loop. The roll rate and control inputs are different in each example.

The reason I defined clearly those two rolls is that they represent the entire field of options as described in the query. Equally the reason for defining a bunt is to understand what the actual goal of the sequence is: To create a positive rate of climb, even if inverted that would allow the pilot to recover the airplane. Initially I discounted the possibility entirely, and I still think a realistic outcome involving a deliberate roll to inverted before the plane pushes itself using negative G to a ballistic trajectory is unlikely in the extreme, but I can come up with a few scenarios, and at least one that would work in theory, and I'll try to post them later when I have time to jot them down.

Finally, as to this topic being off-topic for the thread: Well we can just wait for Boeing to force feed us their solution and accept it no matter what, or we can as a community ask questions and where merited discuss the thoughts that those questions provoke. I find the question challenging as given my own experience it is an interesting idea to explore- certainly in the two accident aircraft the outcome could not have been any worse.

Warm regards,

wonkazoo is offline