Forum: Civil and General Aviation

This thread is mostly about pointless things to do in reality, but I'm still curious to know if they are possible.

1) Is it possible to perform a complete vertical loop with a very large aircraft like a 747? I know there was no reason to design it to do such a thing, but what would happen if it were attempted? Would the 747 break apart? Would it simply stall? What about something a bit smaller like a 757?

2) Let's say that we modify a Concorde to have pitch-vectoring nozzles on its four Olympus turbojets. Would it now be able to successfully pull off a cobra or kulbit? Would the wings snap off? Would the engines stall? Would it crash before it could complete the maneuver? What if we tried it with another vector-modified "big" aircraft, like a Tu-144, XB-70, or even an SR-71?

Yeah it's silly, I know.

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If you could maintain 1 or 2 G in the loop and not exceed Vmo in the process then have at it. But most heavies don't have that kind of pitch authority. I've tried Johnston's Roll in our Airbus and 727 sims at work (off motion, natch) and all the warning horns in the world screamed at me. Laughing

They just don't like doin' that.

The B-47 could do a toss delivery maneuver that amounted to half a Cuban 8 (a "Cuban 4"?) but it was discontinued due to G-induced stress cracks.

Interesting. It seems that it's possible to do a full roll in a 707: http://www.youtube.com/watch?v=3IV9PZW1N9U

Elite 1K Joined: May 26, 2005 - 08:39 PM Posts: 1496

That would be the "Johnston's Roll", as in Tex Johnston, that LinkF16SimDude referred to in his previous post.

Couple things Kryptid, those Olympus engines had ejector nozzles on them so you could kind of bodge a really crude version of thrust vectoring on that using those (and I mean really crude). Trying any extreme maneuvers in heavies is usually a bad idea. The wings are only rated to 2-3g's in civvy planes, maybe up to 5 in some of the short take off cargo planes. Try some crazy stuff and you'll rip the wings off. A loop *might* be possible but there's a lot of consideration, not the least of which is drag when coming out of the loop and if the plane would accelerate out of control and rip the everything off.

Just for a note, the airshow Cobra done by a Su-27/30/etc. is about 13g's on the wing. Part of the reason it can't have stores on it while doing it.

I have done a loop in the KC-135R sim with the motion on. The R model has plenty of power to pull it off, not saying that you don't lose a ton of altitude doing it, but the maneuver is possible.

Loops in a heavy sim.......airspeed freeze.

I can see the NTSB report now.......

"I read this on F-16.net.........hold my beer and watch this."

Shocked

OL

Forum: Civil and General Aviation

Big Maneuvers in the Big Heavies