As I watched the latest SW movie I wondered why planes and spacecrafts do cork screw rolls?

Is there any aerodynamic (not in space) advantge to it?
Is it simply for kicks and giggles?

Why oh why?

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in general spacecraft and satellites tend to rotate in space to more evenly distribute the heat gain by solar radiation so that its not just one side or one section of the spacecraft that is being continually baked or frozen.

Hi Greg,

What I mean is a very fast maneuvre. A cork screw roll coming out of an engagement or when they play the role of the cavalry arriving. Show off.
That is why i wonder if it has any kinetic advantage.

You make a lot of sense, but it's not the roll type i'm referring to.

Thank you.

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quote:

Originally posted by nhtagmember:
in general spacecraft and satellites tend to rotate in space to more evenly distribute the heat gain by solar radiation so that its not just one side or one section of the spacecraft that is being continually baked or frozen.

So they cook evenly on all sides. Like a hotdog

ah, the uncommanded excursion around the longitudinal axis maneuver...

never actually gave it much thought in an aircraft but then again I'm not an aerobatic pilot

In air, any form of maneuvering increases drag and reduces speed and retained energy. Unless you are maneuvering to avoid incoming fire or an interception, or lining up for the next pass, you are just going slower and are more likely to get hit by the next bastard that takes a shot at you. Speed is life.

In space, who the hell knows. It's all for show up there.

If military aircraft I’m going to take a guess that it would give the pilot/crew a view around of other adversaries/trouble/landmarks/danger/friendlies.

I believe what you are referring to is known as a "Victory Roll". It is a aileron roll, technically. And it's mostly pure Hollywood, sort of an expression of exuberance for the viewing audience by the pilot after successfully winning the engagement.

quote:

Originally posted by nhtagmember:
ah, the uncommanded excursion around the longitudinal axis maneuver...

never actually gave it much thought in an aircraft but then again I'm not an aerobatic pilot

There you go!

I'm with OKCGene on this one and aware of what ArtieS said.

Unless you want your stomach contents to be spreaded all over your cockpit/command and navigation room evenly

Thank you all.

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quote:

Originally posted by clubleaf206:
I believe what you are referring to is known as a "Victory Roll". It is a aileron roll, technically. And it's mostly pure Hollywood, sort of an expression of exuberance for the viewing audience by the pilot after successfully winning the engagement.

Yup, indeed.

It's a basic aerobatic maneuver taught in flight school, I think to weed out the non-hackers.

Yeah the Blue Angels / ThunderChickens do them, but once you are in a tactical unit nobody does them 'just to do them', simply because they don't do anything for you. The most you do is 180 degrees of roll to radically change your lift vector in the opposite direction.

Because it’s cool.

I makes the two missiles chasing you bang into each other and explode, especially if you’re a Jedi. We’ve known that for two decades now.

Because hollyweird. An airplane is turned by the horizontal component of lift. Lift is always perpendicular to the wings. When you roll into a 45 degree bank, half of the generated lift goes to turning the airplane, half to combatting gravity. This is why a steady state 45 degree bank level turn involves pulling two Gs.

A fun maneuver that is part of some of the lower category aerobatic competition patterns is the “aerobatic turn”. A properly executed aerobatic turn involves quickly rolling into the desired angle of bank, stopping the roll and neutralizing the ailerons, pulling straight back on the stick to turn the aircraft to the desired heading, “unloading” or releasing the back pressure on the stick thus stopping the turn, then rolling back to wings level.

This is very different from the typical level turn where you coordinate aileron and elevator to smoothly roll into the desired bank while adding just enough back pressure on the stick or yoke to maintain altitude, then smoothly roll out releasing back pressure to maintain altitude as your angle of bank decreases.

Saw Top Gun again a while ago and my son (who is learning to fly) laughed out loud at the “roll to avoid a missile”. A simple aileron roll does nothing to change the vector or direction the aircraft is going. Popping chaff, rolling 90 degrees, then pulling like hell might do some good. Just rolling? Not a darned thing.

The faster the aircraft, the wider the turn. The steeper the bank required to reduce turn radius. An aircraft with a high rate of climb will roll inverted to level off, rather than simply pushing the nose over.

There are two kinds of cockpit loadings; positive g and negative g. Positive pulls you into your seat, draws blood from the head into the body, pools in the legs. Negative g pulls you out of your seat, blood goes to the head. Positive g is a lot more comfortable, and the body tolerates it much better than the other way around.

A rapid climb may involve a roll inverted in order to avoid a negative g condition, or more accurately, to recover to level flight with a positive G.

Lift acts perpendicular to the line that runs from the front of the wing to the back (chord line). Turn on one's side, 90 degree bank, lift is pushing the aircraft through a turn. That's how the airplane turns, by altering the lift.

Simply doing a roll (there are several kinds) in a movie is generally something to look flashy, more akin to a motorcyclist riding a wheelie.

A roll does provide visibility to the pilots blind spot: beneath the airplane, depending on the airplane.

quote:

Originally posted by slosig:

An airplane is turned by the horizontal component of lift. Lift is always perpendicular to the wings. When you roll into a 45 degree bank, half of the generated lift goes to turning the airplane, half to combatting gravity. This is why a steady state 45 degree bank level turn involves pulling two Gs.

All correct except for the last sentence. The trigonometric function that defies the multiplier of the G force in a coordinated turn is the secant of the bank angle. Square root of two (1.414141...) for a 45 degree bank, two Gs for a 60 degree bank.

Back in the dark ages, when I first started instructing (in the 1960s), the steep turn required for private pilot was 60 degrees. At some point the FAA eased this and made it 45 degrees.

quote:

Originally posted by V-Tail:

quote:

Originally posted by slosig:

An airplane is turned by the horizontal component of lift. Lift is always perpendicular to the wings. When you roll into a 45 degree bank, half of the generated lift goes to turning the airplane, half to combatting gravity. This is why a steady state 45 degree bank level turn involves pulling two Gs.

All correct except for the last sentence. The trigonometric function that defies the multiplier of the G force in a coordinated turn is the secant of the bank angle. Square root of two (1.414141...) for a 45 degree bank, two Gs for a 60 degree bank.

Back in the dark ages, when I first started instructing (in the 1960s), the steep turn required for private pilot was 60 degrees. At some point the FAA eased this and made it 45 degrees.

You’re right of course. I‘m not sure how I tangled that up. I can’t even use the excuse of drinking tonight. Sigh...

quote:

Originally posted by slosig:

I‘m not sure how I tangled that up. I can’t even use the excuse of drinking tonight. Sigh...

I think I see your problem.

quote:

neutralizing

I'm glad y'all cleared that up...

quote:

Originally posted by Blume9mm:

quote:

neutralizing

I'm glad y'all cleared that up...

Is there something that you do not understand about the use of this term, related to aircraft control surfaces?

There are several of us here, who can provide an explanation if you need one.