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Vio
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Could The Concorde Do A Loop?

Sat Oct 21, 2006 6:22 am

Hi,

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)

Thanks,

Vio
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EMBQA
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 6:24 am

Any airplane can do a loop... staying in one peice and wings level is another story...
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BoeingOnFinal
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:17 am

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.
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vc10
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:36 am

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.

littlevc10
 
PhilSquares
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:47 am

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.
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vc10
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:55 am

Quoting PhilSquares (Reply 4):
A barrel roll is nothing but a 1 G maneuver

Did I say any thing different

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lehpron
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 8:00 am

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.
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PhilSquares
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 1:25 pm

Quoting VC10 (Reply 5):
Did I say any thing different

littlevc10

Actually you did!

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.

You pull less Gs during a barrel roll than you do in a 60 degree level turn.

The original Boeing 380 prototype also did a barrel roll over Seattle. I suppose you'd have to lump them in the same category as the French?
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vc10
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:22 pm

All I can say is read my original entry, where I suggested that if it was possible the French would have given it a go,however as they had not attempted it then it was probably not possible

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.

littlevc10  smile 
 
PhilSquares
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:49 pm

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.
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FredT
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:49 pm

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...  Smile

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...
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David L
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 7:50 pm

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.
 
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 8:26 pm

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.
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 9:26 pm

Quoting Starlionblue (Reply 12):
As FredT mentioned, aircraft with more than thrust than weight are quite rare.

Not really, there are quite a lot in fact. They are all helicopters. Big grin
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RE: Could The Concorde Do A Loop?

Sat Oct 21, 2006 10:23 pm

Quoting Airfoilsguy (Reply 13):
Quoting Starlionblue (Reply 12):
As FredT mentioned, aircraft with more than thrust than weight are quite rare.

Not really, there are quite a lot in fact. They are all helicopters.

Helicopters don't fly. They're so ugly the ground repels them Big grin
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HaveBlue
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 5:06 am

F-15
F-16
F-22
F-35
Harrier
MiG-29
Su-27
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RichardPrice
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 5:21 am

Quoting HaveBlue (Reply 15):
F-15
F-16
F-22
F-35
Harrier
MiG-29
Su-27

Eurofighter
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GDB
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 7:27 am

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?
 
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 8:06 am

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.
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 8:37 am

Can you withstand 14Gs?
 
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 8:40 am

Quoting AirWillie6475 (Reply 19):
Can you withstand 14Gs?

I don't know if you're asking me, but if so the answer is, "I've never tried to, but probably not. Not without a lot of assistance at least."
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MHG
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 10:48 pm

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!
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 11:18 pm

Quoting PhilSquares (Reply 4):
The Concorde wasn't built to do any type of G maneuvers, so a loop would have been out of the question.

It would have been certified for +2.4 and -1g just like any other aircraft, so it can do a steep turn, or go through a gust.
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SlamClick
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RE: Could The Concorde Do A Loop?

Sun Oct 22, 2006 11:33 pm

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!

While unrelated to looping ability:

Quoting HaveBlue (Reply 15):
F-15
F-16
F-22
F-35
Harrier
MiG-29
Su-27



Quoting RichardPrice (Reply 16):
Eurofighter
EE Lightning

Add this airplane to "thrust > weight" list

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...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.
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727200er
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 3:18 am

The mighty F-104 would need to be listed under more thrust than weight as well.
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lehpron
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 8:39 am

If any airliner's only payload was the pilot and maybe 5% fuel tank or whatever is needed to takeoff, do a loop and then land -- which has the greatest thrust to weight ratio? I think Concorde then 757 would make the grade. Fighter's would classify as rockets by then.

Quoting Starlionblue (Reply 12):
Certainly I cannot think of an aerobatic plane with more thrust than weight

I remember seeing a video online of a white-red-yellow bi-plane called a "Pitts" that would hang in the sky and roll due to engine torque.
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EssentialPowr
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 12:28 pm

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. 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.

What Lehpron???? You're fired due to a very Gross Conceptional Error (GCE) Performing a loop is a function of kinetic energy. A C152 Aerobat doesn't have enough thrust to get out of its own way, but it will do a loop very nicely... SlamClick does a very nice job with the description below:

Quoting SlamClick (Reply 23):
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!
 
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Starlionblue
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 2:50 pm

Quoting Lehpron (Reply 25):
Quoting Starlionblue (Reply 12):
Certainly I cannot think of an aerobatic plane with more thrust than weight

I remember seeing a video online of a white-red-yellow bi-plane called a "Pitts" that would hang in the sky and roll due to engine torque.

Just because I couldn't think of one doesn't mean it doesn't exist.  Wink As SlamClick points out, some aerobatic planes have more thrust than weight. However most do not. Heck I'm pretty sure even the Red Arrows Hawk has less thrust than weight.
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BoeingOnFinal
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 3:20 pm

How about half a loop then half a roll? Then you could start low, and not do the risky last half of the loop.

Cause it would still look awsome if the Concorde did a manuver like that.
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BAE146QT
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 4:36 pm

I can never remember if that's an Immelmann or half of a Split-S
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PhilSquares
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 6:30 pm

Quoting BoeingOnFinal (Reply 28):
I can never remember if that's an Emlynn or half of a Split-S

Immelmann....

Just trying to put things in perspective. I was a T-38 IP and for the loop/cuban 8 our entry parameters were mil power and 500-550KIAS; you should have been 180-200KIAS over the top and roughly 6Gs on the backside of the loop.

The T-38 wasn't an "overpowered" aircraft, but aerobatics is all about energy management.

Quoting Zeke (Reply 22):
It would have been certified for +2.4 and -1g just like any other aircraft, so it can do a steep turn, or go through a gust.

Believe it or not, I do realize that. However, my point was there isn't enough of G available for the Concorde to do an "over the top" maneuver. SlamClick pointed out that you don't have to pull lots of Gs for a loop. However, if the inference is the Concorde could do a loop at +2.4 G, I disagree. The Concord would run out of energy long before it got over the top.
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BAE146QT
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RE: Could The Concorde Do A Loop?

Mon Oct 23, 2006 8:09 pm

Your quoting was a bit on the wonk there, Phil. Thanks for the reply though!
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YYZYYT
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 3:09 am

Strikes me that a good refernece point when considering this would be the TU144 crash in Paris in 1973: there are referneces to tha crash resulting from break-up following abrupt maneuver... at least that is suggested on some respected aviation websites Wink.
here:
http://aviation-safety.net/database/record.php?id=19730603-0&lang=en
and here: Tupolev Tu-144 - A Tribute By Wings (by WINGS Oct 10 2006 in Civil Aviation)
 
Slcpilot
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 3:31 am

Quoting SlamClick (Reply 23):

...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)

With all due respect, it wasn't merely an engine substitution, but a whole new aircraft.



It was essentially a modified Giles-202.

I agree with the rest of SlamClick's comments with respect to looping a transport catagory aircraft. BTW, wasn't that on the list of acro to try with the attempted 747 hijacking in Japan ten years ago or so?

SLCPilot
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SlamClick
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 4:18 am

Quoting SLCPilot (Reply 33):
a whole new aircraft.

Hey, that's the one. Thanks. What an amazing show that was!

Quoting PhilSquares (Reply 30):
The Concord would run out of energy long before it got over the top.

Not disputing this, just wondering if you have an explanation for that, given that, as I said, gliders do loops.
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Slcpilot
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 6:19 am

Quoting PhilSquares (Reply 30):
The Concord would run out of energy long before it got over the top.

Not that we really have any way of settling this discussion, but I suspect Concorde could do a loop if she was lightly loaded.

Different planforms (and airfoils for that matter) will generate lift and induced drag at different rates. We also have to consider the rate of pitch for the aircraft. In other words, if the aircraft could generate a 90 degree nose high attitude, and very rapidly pitch 270 additional degrees, most observers are going to call it a loop, even though it wouldn't score you very high in contest  Wink.

So, could Concorde pitch to a little over 90 degrees nose high? I suspect, especially if lightly loaded and with some extra speed to begin with. Heck it rotated to what, 20 degrees nose high or so on a normal departure. It's the last 90 degrees I would be most concerned about. The TU-144 certainly didn't do very well from this attitude and the attempted recovery.

SLCPilot
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PhilSquares
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 7:26 am

Quoting SlamClick (Reply 34):
Not disputing this, just wondering if you have an explanation for that, given that, as I said, gliders do loops.

One is the wing(swept wing v. straight), the ability to generate potential energy and translate it to kinetic energy.
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litz
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 7:40 am

Quoting Starlionblue (Reply 12):
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.

Weren't there a few (at least one) 707s lost early on due to pilots attempting (particularly on delivery flights) to re-create Tex's roll?

Or is that mythbusters material?

- litz
 
EssentialPowr
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 7:43 am

Quoting SLCPilot (Reply 35):
Not that we really have any way of settling this discussion, but I suspect Concorde could do a loop if she was lightly loaded.



Quoting SLCPilot (Reply 35):

Different planforms (and airfoils for that matter) will generate lift and induced drag at different rates. We also have to consider the rate of pitch for the aircraft. In other words, if the aircraft could generate a 90 degree nose high attitude, and very rapidly pitch 270 additional degrees, most observers are going to call it a loop, even though it wouldn't score you very high in contest .

So, could Concorde pitch to a little over 90 degrees nose high? I suspect, especially if lightly loaded and with some extra speed to begin with. Heck it rotated to what, 20 degrees nose high or so on a normal departure. It's the last 90 degrees I would be most concerned about. The TU-144 certainly didn't do very well from this attitude and the attempted recovery.

SLCPilot,

You get a Gross Conceptional Error (GCE) Award as well. You talk about pitch rates, induced drag and other things but certainly w/o understanding what you are saying. The angle of attack in a loop is pretty low, as it is relative to airflow. Reread what others have written on the topic. As Philsquares, myself and others have mentioned, a loop is a function of kinetic engery management, and is inititated at an airspeed sufficient to complete the maneuver...that is why a glider can do it, as Slamclick mentioned. If the kinetic energy is not present at the beginning of the loop, or the excess thrust required to sustain that energy (generally only available on contemporary fighters), a loop cannot be completed. If you can learn to explain how a glider can do a loop, or a C152, then you may start to accurately understand the physics. Better yet, go do one...
 
SlamClick
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 8:15 am

Quoting PhilSquares (Reply 36):
One is the wing(swept wing v. straight),

Okay, fair enough. I've extrapolated beyond your "swept" to a delta wing and must confess that I've never seen a delta-winged glider, must less see one do a loop. Then I thought about the space shuttle and other than one memorable landing I've never seen one do more than about 1/120 of a loop. I'd go so far as to opine that the shulttle pilots seem to have some disincentive regarding sustained pitch-ups.
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 8:21 am

Quoting AirWillie6475 (Reply 19):
Can you withstand 14Gs?

That depends. Are we talking about sustained Gs, or instantaneous G's? Do we mean surviving, or are we talking about G-induced loss of consciousness?
If you've been in a car crash at 30mph you've already withstood 14G's or more, but only for a very short duration. People can survive forces much higher than that: http://www.stapp.org/stapp.shtml
As for G-LOC, most people can take a sustained 2-3G with no equipment & no special training. Straining exercises can gain 0.5-1G, & an anti-G suit usually nets you another 3-4G. That's just from memory, but my figures should be in the ballpark.
I suspect the only way the Concorde could be successfully looped would be to let the airspeed bleed way down at the top, then keep the alpha high on the backside to keep airspeed down. Maybe!
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SlamClick
Posts: 9576
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 8:43 am

Quoting MissedApproach (Reply 40):
or instantaneous G's?

There is a record up for grabs, it's stood since 1977. David Purley crashed an F1 car into a wall, decelerating from 107 miles per hour in 26 inches. He survived an estimated 179.8 G. To swing this back toward topic, he later took up aerobatics and eventually died in the crash of his Pitts Special.
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
2H4
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 9:14 am




Quoting SlamClick (Reply 39):
I've never seen a delta-winged glider

Here you go, Slam:








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2H4


Intentionally Left Blank
 
Slcpilot
Posts: 568
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 2:09 pm

Quoting Essentialpowr (Reply 38):
SLCPilot,

You get a Gross Conceptional Error (GCE) Award as well. You talk about pitch rates, induced drag and other things but certainly w/o understanding what you are saying. The angle of attack in a loop is pretty low, as it is relative to airflow. Reread what others have written on the topic. As Philsquares, myself and others have mentioned, a loop is a function of kinetic engery management, and is inititated at an airspeed sufficient to complete the maneuver...that is why a glider can do it, as Slamclick mentioned. If the kinetic energy is not present at the beginning of the loop, or the excess thrust required to sustain that energy (generally only available on contemporary fighters), a loop cannot be completed. If you can learn to explain how a glider can do a loop, or a C152, then you may start to accurately understand the physics. Better yet, go do one...

E-power,

Thank you for your lesson. When I used to build aerobatic aircraft we were proud of our airfoil, and its ability to maintain energy through high G loadings. It was designed by John Roncz and our wing was admired for that very quality (e.g. low induced drag at high alpha). The likes of LL, WH, and KC all have testified to this quality, and it's in fact what made the Pitts obsolete in unlimited aerobatics. And your sailplane loop.....low induced drag > right planform!

To perform a loop with a delta wing you need either a low alpha and excess energy for a large diameter, or power to overcome the greater induced drag of a higher angle of attack (like you said). That's not at all inconsistent with what I said. The hardest part is the first 90 degrees for an underpowered aircraft if you're willing to flop through the top. Generally speaking, a delta wing is not good for energy management.

It's not all kinetic energy management. Have you ever seen a helicopter do a loop? I have.

Here's one of my heroes (and somebody I knew personally) talking about loops. Watch the first video.

A link to loop commentary

BTW, what should I use for that loop tomorrow, a Decathlon, RV, or CJ-6? If I want to use an Edge, I'll need to make a phone call.

SLCPilot

PS. Where do I pick up my GCE Award and is there a monetary prize that goes along with it?
I don't like to be fueled by anger, I don't like to be fooled by lust...
 
PhilSquares
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 2:44 pm

Quoting SLCPilot (Reply 43):
To perform a loop with a delta wing you need either a low alpha and excess energy for a large diameter, or power to overcome the greater induced drag of a higher angle of attack (like you said). That's not at all inconsistent with what I said. The hardest part is the first 90 degrees for an underpowered aircraft if you're willing to flop through the top. Generally speaking, a delta wing is not good for energy management.

It's not all kinetic energy management.

Just to clairfy things, for aerobatics in high performance swept wing aircraft it's about TOTAL energy management. For instance in my previous example, the entry parameters for a loop were 500-550KIAS and mil power, with about 180-200KIAS as you go over the top. The vertical profile would be about 10,000' if done properly. The key to the loop is the first half, because you don't want to load the aircraft up as you are getting the nose vertical, because of the very reasons you cited. However, you can manage energy very well as you go over the top by reducing or increasing the angle of attack (g loading) to get to your window at the top of the loop. On the backside, you're transfering potential energy to kinetic energy and G loading will manage any deficiencies you would have.

Personally, I think energy management is no more difficult in a swept wing aircraft if you don't do much maneuvering in the horizontal. Going vertical does two things, it reduces your angle of attack to 0, thus no lift or very little is being produced and you will have very little induced drag, all the thrust is being converted to potential energy. The second thing that happens is your turn radius decreases dramatically in the vertical, conpared with a hard turn in the horizontal.
Fly fast, live slow
 
EssentialPowr
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 10:03 pm

Quoting SLCPilot (Reply 43):
It's not all kinetic energy management.



Quoting PhilSquares (Reply 44):
Just to clairfy things, for aerobatics in high performance swept wing aircraft it's about TOTAL energy management

Absolutely, and in all types. As I and others have stated, performing a loop is completely about energy management, or having sufficient excess thrust (ie, most fighters). "Flopping" through the loop at the top means the energy was not managed properly, pure and simple.
 
YYZYYT
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RE: Could The Concorde Do A Loop?

Tue Oct 24, 2006 10:55 pm

On a related aside, there was a great show on Col. John Boyd on "Legends of Airpower" last night... described as a pioneer in the very field of kinetic energy management. Fascinating tv (at least form a lay perspective) and fascinating reading. Thanks all.
 
prebennorholm
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RE: Could The Concorde Do A Loop?

Wed Oct 25, 2006 3:53 am

There is absolutely no doubt that a plane with the shape, power and empty weight of a concorde (plus a little fuel) could do a loop. But it's a big question wether the Concorde could do it.

For this altra high speed plane it is strange, but the limiting factor would in fact be maximum allowable speed.

It would have to be done at rather low altitude, both to keep the diameter within reasonable scales and to keep the engine power high. At low altitude the VNE of the Concorde was not impressive at all, if memory serves me well it was something like 340 kts.

Would an entry speed of 340 kts be enough? Maybe?

But what would keep the speed down during the second half of the loop? Extending the landing gear would help a lot. But then I don't know the VNE with gear down. It was most likely a lot lower than 340 kts.

The G force would not be a problem. The Concorde was designed for 2.5 G like any other airliner - at MTOW. With little fuel on board and no payload the weight was half meaning that it was in that configuration "designed for 5 G". (Well, some payload wouldn't make much difference, the payload was so small, less than 10% of normal fuel load - only 60% of normal fuel reserves. A Concorde making an evenltess flight LHR-JFK with every seat occupied would land with 9 tons payload an 15 tons fuel on board).

But a loop with something like a high fuel load, that's something we can just forget about.

I have only heard about one four engined airliner doing a loop. It was a Focke-Wulff FW-200 Condor, and it happened in Aalborg, Denmark in 1938. The company test pilot did it at a demonstration flight, and DDL (Danish Airlines - later merged into SAS) immediately bought two of them.

Those Condors didn't last long into WWII. One was in London when the war started, could not return and was later destroyed by a German attack. The other one suffered a slight mech in Prague, could not be repaired and "disappeared". It was probably quite soon repaired and put into Luftwaffe service.
Always keep your number of landings equal to your number of take-offs
 
AC320tech
Posts: 193
Joined: Mon Jul 31, 2006 6:32 am

RE: Could The Concorde Do A Loop?

Wed Oct 25, 2006 3:58 am

Quoting EMBQA (Reply 1):
Any airplane can do a loop... staying in one peice and wings level is another story...

Not entirely true. Airbus's with FBW cannot do loops. Flight Computers prohibit the plane going past 30 degrees up and 15 down.
 
Venus6971
Posts: 1415
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RE: Could The Concorde Do A Loop?

Wed Oct 25, 2006 4:01 am

Saw a GAANG B-1 do a loop with the wing DO flying it right before he retired and they transitioned to the E-8 JSTAR at the OKC air show. Quite a site.
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