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Originally posted by FFrench:
I mentioned this story to him, and Bob said he'd never heard it before... "not that it couldn't have happened, but I think I'd have heard it." I was wondering what your source might be?

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Originally posted by ejectr:
...got a reply that the General said you can't roll a B29.

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Originally posted by machbusterman:
My source regarding the roll was BGEN Cardenas himself.

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Originally posted by machbusterman:
...even the B-36 has been rolled so not sure why he thinks it wasn't possible.

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There are some details the best test-pilots never give up. Like the day Chuck Yeager broke the speed of sound. It was Cardenas who flew the B-29 launch plane that carried Yeager's X-1 aloft. Afterward, Yeager did a victory roll. And Cardenas?

Legend has it, he did his own victory roll in that big old B-29 – something strictly forbidden.

Did he?

"I swore the whole crew to secrecy," he says, a twinkle in those old eyes. "Or I would've been grounded!"

Rolling an aircraft that large carries all kinds of hazards, the two primary ones are causing stress on the wings beyond their design capabilities, and creating an inverted conditions inside the fuel tanks, where the fuel is interrupted.

You quite clearly can't do a barrel roll like you can in a modern fighter plane, you pretty much have to corkscrew it to create a positive 1G condition inside the aircraft the entire time. The famous roll of the Boeing 707 demonstrator aircraft over Lake Washington shows how to do it very well. In that case, the plane was rolled in a corkscrew manner, and created a 1G condition inside the aircraft the entire time. The engineers, in consultation with the aircrew, confirmed that such a maneuver would cause absolutely no problems with the airframe at all.

The B-52 crash at Fairchild Air Force Base in 1994, shows the opposite. The pilot involved was a real hot dog, and should have been grounded years before, due to all kinds of unsafe conditions and a climate of tolerance on the part of the chain of command. He had told people on numerous occasions his lifetime goal was to roll a B-52. He was scheduled to fly at an airshow the following day, and many people at the base were convinced he was going to try it, as his retirement was very close at hand at that point.

Anyone unfamiliar with the "Bud" Holland mishap that wishes to know more should read this.

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Originally posted by p51:
You quite clearly can't do a barrel roll like you can in a modern fighter plane, you pretty much have to corkscrew it to create a positive 1G condition inside the aircraft the entire time.

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As you hint, rolling large non-acrobatic types risks exceedance of one or all of four parameters: the airspeed/Mach limit, the normal load factor ("g-limit"), engine fuel feed capability and available separation from Mother Earth. Overlaid upon this are the facts that most (but not all) large airframe drivers never had much acro training, are not acro current, don't really understand the maneuver they are trying to fly and, obviously have no training in rolling the type in question. Another consideration is that most large airplanes lack an accelerometer, forcing the pilot to fly by the seat of his pants. Of course, not being an acrobatic pilot his "seat" is uncalibrated. The maneuver will also require control forces and deflections that feel "unnatural" for the inexperienced pilot, potentially causing them to unintentionally back off at the wrong moment.

For most types, large props or jets, the problem is a matter of trading roll rate — which varies with speed, against the tendency of the nose to want to fall through. The option to hold the nose up with negative load factor is generally unavailable because it will induce engine fuel starvation, (which can also have secondary and unpleasant hydraulic and/or electrical consequences in modern types).

There is absolutely no requirement to maintain positive 1g all the way round, and attempting to chase that target can result in an extremely dangerous nose low condition. Many very experienced guys talk about "maintaining 1g all they way round", they know how to fly but they don't mean what they say literally. You are best off entering at high speed and then raising the nose prior to initiating the roll in a "barrel roll-style" entry, with the airplane trimmed for an intermediate speed. Note that this is not an attempt at a perfect air show or academic barrel roll.

How high to raise the nose depends upon how quickly the type looses speed, and how quickly it can roll. Generally the slower the roll the higher you'd like the nose to be at the start; and the quicker you loose speed the less you can raise it. Of course, the higher you raise the nose the quicker you slow down and the slower you roll. The relationship between these is not linear. As you slow down and your maximum roll rate reduces — you may find this happening much faster than you expected. Use the rudder to minimise sideslip, but do not "peddle" it back and forth, that can take the whole vertical stabilizer off a large airplane. Use back pressure to maintain positive g, but allowing it to reach a fairly low figure depending upon your loss of speed — which may well fall significantly below 1g stall speed. It's not a problem, angle of attack determines stall, not speed.

Done right you will stay well within placard limits, not shutdown the engines and loose little altitude. Done wrong, you will at best loose tremendous altitude and almost certainly overstress the airframe in a "high g" spiral as panic sets in. The post-grad version of this is being able to do it at night. Always build up gradually via steep turns then wing overs so you know, rather than guess at the airplanes handling characteristics. Have a plan of how to abort the maneuver at any stage.

Better still, don't do it unless you know what you're doing or it's a war and you have nothing to loose. I've seen too many guys exceed their own abilities and knowledge, sometimes with fatal results.