Vio From Canada, joined Feb 2004, 1507 posts, RR: 10 Posted (8 years 7 months 1 week 1 day 1 hour ago) and read 12895 times:
Here's a silly question. Could the Concorde do a loop? I was looking at photos from some of "its" last flights. Consider that there would be no passengers in the back would this airplane have enough power for that and still be structurally sound enough to perform such a manouver? (I wonder if the pilots "tried" anything new with her on her last flight)
Superior decisions reduce the need for superior skills.
PhilSquares From , joined Dec 1969, posts, RR:
Reply 4, posted (8 years 7 months 1 week 23 hours ago) and read 12852 times:
Quoting VC10 (Reply 3): The French were mad enough to barrel roll Concorde, and more than once, so if it was plausible to loop it I am sure they would have, but I have never heard of it.
A barrel roll is nothing but a 1 G maneuver. Doing a loop is another thing though. The Concorde wasn't built to do any type of G maneuvers, so a loop would have been out of the question.
Now for all the "experts" out there, you could do a loop that required just over 1 G, however, you would have to have almost unlimited thrust available, which wasn't the case with the Concorde. If you don't have unlimited thrust available then you will run out of airspeed before you get your nose down on the back side of the loop. Not a great place to be.
Lehpron From United States of America, joined Jul 2001, 7028 posts, RR: 20
Reply 6, posted (8 years 7 months 1 week 23 hours ago) and read 12836 times:
It is a question of thrust to weight. Stunt planes and airshow fighter jets have more than their weight in thrust, so they can pitch up and over loop. Concorde was maginally more powerful than every other airliner in the world. She was designed for straight-level performance, just because she looked like a fighter jet doesn't mean she could perform like one.
Technically, a plane would have to be moving really fast & straight level at the begining because almost all the of speed would be lost to altitude (knetic energy to potential) until the apex velocity was just above stall. Like any airliner of similar class, going past 2.5g's makes structural failure is imminent.
For aircraft as large as Concorde in mass, I think a 763 would classify, a 1g pitch up loop would be difficult to complete more than 90-degrees pitch, I think they would stall due to not having enough thrust to overcome gravity and drag, to keep going up and over.
The meaning of life is curiosity; we were put on this planet to explore opportunities.
PhilSquares From , joined Dec 1969, posts, RR:
Reply 9, posted (8 years 7 months 1 week 11 hours ago) and read 12690 times:
Quoting VC10 (Reply 8): I think you would have to agree that barrel rolling a airliner is not considered just another maneuver, but if you insist it is, well that is OK with me.
Please re-read my post. I never insinuated, implied or stated a barrel roll in a transport category aircraft was "just another maneuver". My statement was a barrel roll is a 1 g maneuver that when put in the context of a steep banked turn, has less g loading on the aircraft.
The original poster asked about the feasibility of the Concorde doing a loop. Given the g loading required and the lack of excess thrust, my opinion was no. It wasn't about if the french did barrel rolls or anything like that.
FredT From United Kingdom, joined Feb 2002, 2185 posts, RR: 26
Reply 10, posted (8 years 7 months 1 week 11 hours ago) and read 12687 times:
Quoting BoeingOnFinal (Reply 2): Isn't there some issues other than structural endurance? At least in a Cessna, the carburetor won't get any fuel and the engine will stop, but I guess that is because it doesn't have a fuel pump.
That happens when you pull negative Gs. If you maintain positive Gs all the way around the loop, it won't be a problem.
To perform a loop, an aircraft needs to be able to pull the Gs required and have enough energy to cope with the climbing part of the loop and the drag generated by pulling Gs. That's all there is to it. The energy can come from excess speed or engine power.
The Concorde wasn't exactly overpowered, and it generated huge amounts of drag as you increased the AoA (as you would when performing a loop). It did have a lot of smash in the form of kinetic energy at high speed though, so just maybe, if you brought it up to speed, put it into afterburner and pulled...
If we had the performance data (the real data, not the boiled down data in the AFM), it would be possible to calculate. How much is in the public realm?
Quoting Lehpron (Reply 6): Stunt planes and airshow fighter jets have more than their weight in thrust
Only a select few do...
I thought I was doing good trying to avoid those airport hotels... and look at me now.
Starlionblue From Greenland, joined Feb 2004, 17303 posts, RR: 67
Reply 12, posted (8 years 7 months 1 week 11 hours ago) and read 12676 times:
Quoting David L (Reply 11): Quoting VC10 (Reply 8):
I think you would have to agree that barrel rolling a airliner is not considered just another maneuver
I was under the impression that it was considered taboo due to public perception more than anything else, considering that it's an unnecessary manoeuvre.
There's also the pesky fact that aerobatics in airliners aren't officially tested, and thus there is little data on their viability. Unpredicted problems may well occur.
Quoting Lehpron (Reply 6): It is a question of thrust to weight. Stunt planes and airshow fighter jets have more than their weight in thrust, so they can pitch up and over loop.
As FredT mentioned, aircraft with more than thrust than weight are quite rare. Certainly I cannot think of an aerobatic plane with more thrust than weight. Some fighters like the Su-27 are this powerful. Aerobatic planes achieve loops and such by using built-up kinetic energy as opposed to raw thrust.
"There are no stupid questions, but there are a lot of inquisitive idiots."
GDB From United Kingdom, joined May 2001, 13386 posts, RR: 77
Reply 17, posted (8 years 7 months 1 week ago) and read 12479 times:
Well it's not some that was ever discussed in my time, nor I suspect anyone else's on the fleet.
As for it's last flights, they were full of pax, all of them, I should know being on the last but one, also being the last international one (to BGI), as for 'not exactly being overpowered' it did not feel like that, I can assure you-any airliners with a thrust to weight ratio similar to a supersonic fighter?
BAe146QT From United Kingdom, joined Sep 2006, 996 posts, RR: 0
Reply 18, posted (8 years 7 months 6 days 23 hours ago) and read 12470 times:
Quoting PhilSquares (Reply 7): I suppose you'd have to lump them in the same category as the French?
I never met Tex Johnson, but I've seen videos of him flying, (including the infamous "chandelle, roll, chandelle, roll" over the boat show.
Whether he was crazy or not is between him and his doctor. What I CAN say is, the man was an artist with a vast blue canvas.
I've heard various iterations of the story of that particular day (and the aftermath) including that he was fired then rehired, or that the boss just hauled him over the carpet then invited him over to dinner.
Either way - and notwithstanding the fact that rolling the Dash 80 wasn't exactly dangerous as such - you have to admire the size of the man's huevos for doing it at all.
Quoting Starlionblue (Reply 12): Aerobatic planes achieve loops and such by using built-up kinetic energy as opposed to raw thrust.
I seem to recall that certain WWII fighters achieved the manoevre by entering a shallow dive at WOT prior to pulling up. This would certainly back up your statement, (not that I think it needed it).
Personally, I think that if it was possible to loop the Concorde, you would do it precisely once and never again.
MHG From Germany, joined Dec 2004, 826 posts, RR: 1
Reply 21, posted (8 years 7 months 6 days 8 hours ago) and read 12361 times:
I think there are simply 2 facts (related to each other) that let the Concorde NOT make a loop:
1) The structure was not designed for such G-stress.
The a/c certainly had enough power to build up enough kinetic energy to perform the loop.
But especially the interception maneuvre on the way down from the top would overstress the structure since the a/c has no speed brakes to reduce/limit acceleration.
2) The loop diameter would be extraordinary huge in any case (plus sufficient base altitude to start from to ensure a safe interception on the way down) but in particular to keep the airframe stress low enough to ensure it doesn´t break apart already on the way up!
SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 67
Reply 23, posted (8 years 7 months 6 days 8 hours ago) and read 12343 times:
Sure a lot of opinions offered by people who don't have a realistic idea of what a loop requires. Not a lot of aerobatic experience? I don't either but let me clear up a couple points.
• An airplane does not need gobs of thrust to do a loop.
Gliders do loops all the time. You start at a higher altitude, dive a bit to gain speed, which is energy, then pull smoothly back and the surplus energy carries the nose up past the vertical. After that, keep pulling and gravity begins to lend a hand.
• An loop does not generate a hundred Gs.
Loops can be done all day long without exceeding 2.5G which happens to be the limit for "transport category" airplanes. If Concorde would not withstand that kind of load it would have disintegrated in turbulence long ago.
• An airplane does not have to go negative to do a loop.
A nice round "barnstormer's" loop will hang you in the straps while going over the top. A glider loop will keep the coffee in your thermos cup all the way around. How hard do you want to pull coming over the top?
I would suspect that the biggest problem in looping Concorde would not be the entry but in preventing too much speed buildup on the downhill half. Not that it couldn't tolerate higher speeds but that same G at higher speeds increases the radius of the loop. Concorde could not withstand the results of running out of sky after 7/8 of a loop!
...after Wayne Handley put a P&W PT-6A on it and before the prop stuck in beta and crashed him into the ground. (...coming out of a loop)
I saw one of his last shows at Reno with that plane. (maybe the last complete show) He would pull it straight up, then reduce power and lower it down tail-first, hanging on the prop. Then he would add power and the hovering airplane would begin to climb, accelerating away from the ground all the while going straight up. It was the most amazing airshow act I have ever seen and I have seen all the big names over the last forty years.
Happiness is not seeing another trite Ste. Maarten photo all week long.