BeermatThanks, Baz 🙂
BeermatSo in the same manner as the not-exactly barrel and not-exactly aileron roll that nets you 1G throughout, is it possible to fly a similar cross between an aileron roll and a slow roll to wind up with a net glove-floating 0G for at least a portion of it? I have heard of (but never knowingly seen or experienced) a ‘ballistic roll’ – taught by some schools as a way of reducing aerodynamic loads to zero – is that what this is?
I read too many books, that’s my problem. They’re all written by untrustorthy blaggards like Newton and that notorious bullsh***er Henshaw, anyway. I should regard books and those who read them with derision – maybe then I’ll be more like an American fifth grader..
BeermatPrecisely.
How long depends upon the trajectory of the aircraft. Gravity is effectively an absolute (thank you, pedants;)), but if the aircraft is describing a suitable trajectory then its effect in terms of the motion of items within said aircraft can be apparently (and temporarily) negated – take a look at what NASA/JPL do with their ‘vomit comet’ progam.
It is only when the aircraft deviates from such an arc that things will appear to move in a relative sense. The attitude of the aircraft makes no difference to this in physics terms (though in real life it is much harder to get the aircraft to describe the appropriate arc when it’s also rolling).
I fear I have been undermined by Henshaw’s loose phrasing in such a necessarily precise argument! I suspect he never expected it it be picked apart like this 🙂
BeermatThis is not YouTube.
This is a serious forum for grown-up people who either know what they are talking about or know when to shut up. I agree that YouTube is full of idiots, and when it comes to aircraft, it seems that everyone’s a pilot. You will notice by contrast that no-one here ever refers to their own experience, hours etc. Maybe it is because it is predominanantly British. Some research, however, and you might be surprised.
Maybe that experience has made you approach this forum with a more confrontational attitude than is appropriate.
We are not all 20,000 hour plus pilots, but we are not all idiots either. It is possible to be neither or both.
I mean this in a friendly way, and yes, I would welcome the chance to have a chat with you – it seems we have got off on the wrong foot.
Yes, I have read a lot of books – guilty as charged. However, I do not claim to be an expert. Please don’t shoot me down for referring to a book written by a very respected pilot with some grand experiences of his own – it was not meant to antagonise you. I am interested in your refutation of the physics involved – genuinely – though PM might be more appropriate as granted it is off-topic.
Cheers,
Matt
BeermatHi Fanavion
I cannot defend Alex Henshaw’s phraseology – it was an imprecise figure of speech. Nothing ‘suspends’ anything, he was describing a position of relative stasis – the physical effect being that the absolute sum of the forces on both objects (aircraft and glove) are equal – both objects are in motion, but as a result of this equilibrium, they are in equal motion. I refer you again to I. Newton.
Consequently, the answer to the second question is absolutely with reference to the aircraft.
I don’t know the figure to answer the third question, but the fourth, elswhere in the chapter ‘Rolling the Lancaster’ seems to be that towards the end of the roll (I cannot be more precise as Henshaw wasn’t) and as the plane levelled out, so the object returned to 1G and settled back to a position of rest (although here he was referring to a passenger. No mention is made of what happened to the gloves)!
Thank you for being reasonable like most people here, and not rude like one.
BeermatWell, there were a few beards and we all went to the pub afterwards. I believe that’s what archaeologists do – you mean there’s more to it than that?:diablo:
BeermatSorry, I meant ‘participated in the investigation, based upon sound archaeological principles’ 😉 Sadly this isn’t entirely true – it was the early eighties, and I was 13. With hindsight I wish it was.
Cann’s farm, Puriton?
BeermatSomerset Heinkel? Which one, Andy? (did a few in my time)..
BeermatA direct quote from A. Henshaw -‘Sigh for a Merlin’:
“..the controllability of the Lancaster in a roll was such that I amazed myself more than once by the manner in which a glove, left on top of the instrument panel ledge, could be gently suspended in the air as the machine seemed to roll around it or, if I had a passenger without a harness on, I was able to go over with his bottom a quarter of an inch from the seat until we had completed the roll and we were at positive ‘G’ again.”
DD, are you calling this man a liar?
..and later:
“I gently eased the controls so that his feet left the floor slightly”
DD, this precisely the touch of negative G referred to – with no accelerative force, there is no movement. Objects, or people, don’t just float upwards at 0G. Of course, it’s the application of a force to the aircraft and not the body that is the key here, and the cause of relative movement.
However, I no longer expect to hear from you – a classic flamer.
Beermatwould make a fifth grader snicker.
I am still waiting for an apology for your rudeness.
BeermatYour statement “In fact, the claim was for zero G, with only a touch of negative at one point sufficient to ‘lift’ the glove into the position where it then remained static relative to the aircraft.” would make a fifth grader snicker. How can you be zero G with a touch of negative?
You are not looking at an elementary number line with a zero dividing positive and negative numbers when you consider units of gravity.
Your fifth graders must know more than Physics graduates in the UK (or this one, at least).
I was not confusing the 1G experienced by the passenger with the 0G ‘experienced’ by the glove on a seperate occasion. Please read posts properly before shooting. Furthermore it is rude to suggest infantilism or assume superior knowledge, whether you drive Douglasses or not. You need to display better manners as a newbie.
You know that I meant negative in the sense of the direction of the apparent force. You also know that I meant a momentary apparent (or relative) force, ‘lifting’ the glove, followed by a subsequent nullification of that apparent force to hold it there in a state of ‘weightlessness’, due to the relative ‘moments of inertia’ of plane and object subsequently being made equal by the actions of the pilot.
I hope that you also know that I understand the principles of gravity – and more pertinently inertia – as well as you do.
‘Anyone with any aerobatic experience’ will be familiar with objects floating up in the manner of that glove. All Mr Henshaw was talking about was the ability to then keep it there. I suspect it is a perfectly feasible yet tricky manouvre rather like rolling a ‘vomit comet’ during a ‘Zero G’ switchback. Please see http://jsc-aircraft-ops.jsc.nasa.gov/Reduced_Gravity/trajectory.html – and note the ‘negative G’ option – a touch negative, anyway.
Neither myself or NASA/JSC are claiming that it is possible to be ‘both 0G and a touch of negative’ – but both are attainable consecutively.
It is thus perhaps – and this is my argument – theoretically possible to ‘park’ an object as described above and then perform an aileron roll around the longitudinal axis while flying a trajectory required to silmoultaneously maintain the entire system in a 0G state. Just, I suspect, very difficult – and that is why it was worthy of mention when a pilot achieved it.
The ‘someone else’s book’ in my sign off is, in this case, Philosophiæ Naturalis Principia Mathematica by Isaac Newton.
Yours at 1G
Matt
BeermatAnyone with any aerobatic experience will understand the maneuver can’t be flown in a negative G throughout to revolve around a “floating” object.
Oooh, get you!
To be fair, although the ‘pull up’ bit of the quote is confusing, no-one claimed negative G throughout. In fact, the claim was for zero G, with only a touch of negative at one point sufficient to ‘lift’ the glove into the position where it then remained static relative to the aircraft. The engineer in this quote – a different occasion from the glove anecdote – was surprised simply because the G regime felt ‘normal’, and so he wasn’t expecting to be upside down when he looked ‘up’. This is probably a different occasion again from the (possibly apocryphal, I don’t know) story of Mr Henshaw repeating the glove trick with a passenger.
I would suspect that this manouver was very far from a textbook roll of any kind, and entailed a major loss of height (maybe a spot of relative free fall would help in getting that glove floating). However, I don’t imagine ‘sloppy’ was in this man’s repetoire.
BeermatOK, thanks all for looking – we’ll start fabricating ribs tomorrow. Hope I didn’t give the impression that our working plans were drawn on the back of a ciggy packet one afternoon – it’s the general arrangements (of which these are a synthesis of several different photographs that were chosen because they agree – many don’t) that I was checking.
BeermatAlex Henshaw himself defended the rolling of a Lancaster in exactly the same way – it was only a 1G manoeuvre, the way he did it. But then, the accuracy of his flying was legendary. In fact, I have heard that he had fun placing objects – and on at least one occasion a surprised passenger – neatly in space at 0 relative G and rolling the aircraft around them.
Equally, though, an aerobatic barrel roll needn’t be – and often isn’t – just 1G. The most G I have felt was deliberately applied to me in the back seat of Goodwood’s Harvard, put through an equally perfect barrel roll by Dieter Sinanan.
So when talking about the stresses on an airframe during a manoeuvre – well, it depends how the manoeuvre is flown.
BeermatHaha – needn’t have asked, eh Tim? 🙂 Sorry, I hadn’t picked up on the details your post-war career before now.
Sign In
