Lockheed Martin loops Hercules at Farnborough 2018
Gnome de PPRuNe
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BY the way Tex in his own words called his manuver a chandelle- not a ' barrel ' roll
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Interesting- in technical terms a chandelle is a climbing turn nomally to change direction by 180 degrees. yet a video shows no 180 degree change in direction but more like 30 or 40 degrees. Of course he may be referring to the fact that AFTER the first Roll- he did change direction about 180 degrees to fly back over the hydroplane course and repeat the " roll" . What is not well known were the comments I heard personally about 15 -20 years later by/from the then young boeing pilot flying chase that day - and perhaps there may be some possible film from the then used gun cameras since on that day the dash 80 was normally on a scheduled flight test. The chase pilot did NOT know of tex plans and was simply flying quite aways back in trail to avoid distraction as tex was to fly low over the hydro race course. His normal reaction was to follow the dash 80 in all positions. So as Tex rolled -chase simply followed and chase realized all of a sudden he ( chase) was low, relatively slow, and upside down- and if the dash 80 came unglued he chase could not probably avoid a collision or safely eject - so he keyed mike and started to call mayday - tex said firmly shut up kid !- after landing, the feds were a bit upset and insisted that chase HAD to have known what tex was going to do- which of course was verboten. What saved chase was the then used tape recordings . . .
We might return to Sir Isaac. A derivation of his second law of motion is F=Ma.
F = force
M = mass (quantity of matter per unit volume.
a = acceleration (rate of change of velocity)
Thus: for a given mass and g being gravitational acceleration the derived force is called weight.
Therefore if g were zero the aeroplane would be weightless.
F = force
M = mass (quantity of matter per unit volume.
a = acceleration (rate of change of velocity)
Thus: for a given mass and g being gravitational acceleration the derived force is called weight.
Therefore if g were zero the aeroplane would be weightless.
When I was first studying aeromechanics some 40+ years ago, in the UK, the convention on this side of the water was to define S+L flight as 0g. Apart from anything else, that makes concepts like "stick force per g" much more intuitive, since of course stick force in straight and level flight is zero.
We were, however cautioned that other less enlightened nations used the 1g convention, so we should be prepared to meet that in our careers and now, like many other transatlantic imports, it's pretty well universal.
But to return to the topic - whichever convention you choose, the proposition that you can fly a loop while pulling no more g than in level flight is clearly ludicrous.
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When I was first studying aeromechanics some 40+ years ago, in the UK, the convention on this side of the water was to define S+L flight as 0g.
I taught university aeronautics for some years and +1g was a teaching requirement.
So what g am I experiencing sat here on my sofa ?
Your turn.....
The issue here is that 'g' has several meanings. If we keep it simple in the context of manoeuvring aeroplanes and say that 'g' is load factor (Lift/Weight) which is also what it says on the g meter in the cockpit then discussions on this thread become clearer for all who fly.
Dook,
With respect to sitting on your sofa, how are you defining g? I would say that the sofa is exerting an upwards force on your posterior that is equal and opposite to your weight, which is your mass in kgs x g, with g being 9.81 m/sec2.
Dook,
With respect to sitting on your sofa, how are you defining g? I would say that the sofa is exerting an upwards force on your posterior that is equal and opposite to your weight, which is your mass in kgs x g, with g being 9.81 m/sec2.
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…..which is your mass in kgs x g, with g being 9.81 m/sec2.
In my court it's lbs and 32 ft/sec squared. Non of this metric crap.
However, I get extremely irritated by ignorant people who use the phrase "g force".
If you choose to use the "0g" reference for S+L, then how do you reference the equivalent "weightless G" where an object (or your body) "floats weightlessly" within a space?? (eg the cockpit/cabin) - is that then referred to -1g??
Absurdity...
Absurdity...
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NO ITS ZERO G.. As in the space station which is continually falling towards the earth in an appropriate circular path. Or in the ' vomit comet " parabolic flight path of the NASA 707 which temporarily matches the circular flight path which results in the outward g vector matching the to center of the earth vector known as + i G- sort of like flying in an outward ( cockpit ) reference LOOP !!! ARRRRRGGHHHHHHH !
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So what g am I experiencing sat here on my sofa ?
Tex in his own words called his manuver a chandelle- not a ' barrel ' roll
Tex lived a long time by NOT being stupid or taking dumb risks with a new designed airplane NOT designed or stressed for aerobatics
A longer vid on the B-47 maneuver capability research
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But that has zip to do with defining airplane ref g's versus world ref g's and NO attempts to do a 1 g roll.
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Rather weird chandelle. Tex said, page 217, "During the two barrel rolls the airplane never knew it was inverted"
+++
Rather weird chandelle. Tex said, page 217, "During the two barrel rolls the airplane never knew it was inverted"Tex lived a long life because he knew what he was doing, aka, you can do aerobatics in an aircraft not designed for same if you have the knowledge and skill. Bob Hoover in the Aero Commander and Sabreliner was doing the same, aerobatics in aircraft not designed for same. Very much doubt the B-47 was designed for aerobatics, yet it was used in a toss bombing role, half loop and roll off the top. Of course it took a toll on the airframe eventually.
https://www.youtube.com/watch?v=gzY8LNKPeEk
A longer vid on the B-47 maneuver capability research
https://www.youtube.com/watch?v=6cIgTAtj4E4
https://www.youtube.com/watch?v=gzY8LNKPeEk
A longer vid on the B-47 maneuver capability research
https://www.youtube.com/watch?v=6cIgTAtj4E4
Absent a significant amount of posterior propulsion in the vertical plane, and assuming no other movements, convention would rate you at 1 G
While Tex said "chandelle" in the clip, the fact is, it was not a chandelle, and the video in the clip is proof of that, as is the famous photograph. Tex mis-spoke in the video. The FAA in fact require a pilot to perform a chandelle for licensing purposes, none of those Pipers and Cessnas are aerobatic, so performance of your definition of "chandelle" would be illegal, but they perform the manoeuvre day after day. Page 5 here,
https://www.faa.gov/regulations_poli...11_afh_ch9.pdf
Last edited by megan; 22nd Jul 2018 at 05:45.
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never have tried or used the microsquish simmer- I use an apple and have for way to many decades. And about 25 years ago - apple had a simple sim- which I tried once and went on to do other things . So what ref do you use for the ' impossible ' 1 G - in the cockpit g meter or in the real world ? and exactly 1.00000 G or a nominal 1 G ? re airplane /cockpit ref? or the real world ref with vector to center of earth ?
Sorry, I didn't think that in a professional forum that would need saying ...
We could argue all day about whether "stick force per g" or "stick force per (g-1)" is more intuitive. Let's not
My aeromechanics lecturer was Polish, by the way, maybe it's an Eastern European convention that the RAF was keen to avoid.
Anyway, as I've already acknowledged, it's a convention that has completely died out (a bit like the British English definition of "billion") now that the USA has taken over the world.
Dave old lad.....do keep up please.
We speak of “Trillions” especially when we speak of our Federal government’s spending habits.....as it likes to spend far more than it has in its Purse each year.
Pilots can relate to that kind of spending habit!
We speak of “Trillions” especially when we speak of our Federal government’s spending habits.....as it likes to spend far more than it has in its Purse each year.
Pilots can relate to that kind of spending habit!
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Jeeze megan - please read my posts again and listen to the link I initially posted re tex- in which I simply commented that in his own words, HE called it a chandelle- and I mentioned in that same post it was a barrell role. I latet commented that it was NOT a chandelle and thattex may have been referring to the turning around in a short distance - chandelle - to come back over the race course. Yet you seem to claim I did NOT properly define a chandelle ??
its a bit late to explain to Tex that he used the wrong definition - which I simply mentioned that In his own words is what he said and posted the proof re the video
Why not give it a rest ????
so performance of your definition of "chandelle" would be illegal, but they perform the manoeuvre day after day. Page 5 here,
its a bit late to explain to Tex that he used the wrong definition - which I simply mentioned that In his own words is what he said and posted the proof re the video
Why not give it a rest ????
CONSO, flying straight and level inverted (hanging in the straps) what "g" would I be experiencing, minus one, zero, plus one?
The definition of 1 G still applies whether you are standing on your head or your feet reference to the earth - it that case you are simply ' on your head ' at 1 G . . . convention would be PLUS one g in straight and level upside down flight even though your internal reference frame would show MINUS one- - context and refderence frame matters !!
While Tex said "chandelle" in the clip, the fact is, it was not a chandelle, and the video in the clip is proof of that, as is the famous photograph. Tex mis-spoke in the video.
THATS WHAT I SAID !!!
The FAA in fact require a pilot to perform a chandelle for licensing purposes, none of those Pipers and Cessnas are aerobatic, so performance of your definition of "chandelle" would be illegal, but they perform the manoeuvre day after day. Page 5 here,
https://www.faa.gov/regulations_poli...11_afh_ch9.pdf
The definition of 1 G still applies whether you are standing on your head or your feet reference to the earth - it that case you are simply ' on your head ' at 1 G . . . convention would be PLUS one g in straight and level upside down flight even though your internal reference frame would show MINUS one- - context and refderence frame matters !!
While Tex said "chandelle" in the clip, the fact is, it was not a chandelle, and the video in the clip is proof of that, as is the famous photograph. Tex mis-spoke in the video.
THATS WHAT I SAID !!!
The FAA in fact require a pilot to perform a chandelle for licensing purposes, none of those Pipers and Cessnas are aerobatic, so performance of your definition of "chandelle" would be illegal, but they perform the manoeuvre day after day. Page 5 here,
https://www.faa.gov/regulations_poli...11_afh_ch9.pdf