looping the loop - with a difference.

[shed driver]

Really odd question, but given enough room, could a submarine "loop the loop"? I understand it would be pretty messy and dangerous on board, but is it actually possible?

SD

[Simpo Two]

doogz said:

Would probably require some jiggery pokery with the ballast tanks around vertical to get it to tip over

Bah, just get some speed on and use the hydroplanes!

[RDM]

Don't tell Hollywood about this, it'll make The Hunt for Red October II utterly ridiculous

[Simpo Two]

doogz said:

Ever seen "Santa Clause: The Movie"?

Is the 'Santa Clause' the bit in a company's T&Cs that says you might get your order by Christmas?

[simonrockman]

If you could pull 1G you wouldn't even fall around inside.

Simon

[RDM]

Quote from the new Hollywood version of HuntforRedOctober.

"How did you see the Russian Akula if you were in 1G loop"

"We were inverted!"

[rhinochopig]

TheLastPost said:

There are, of course, submersibles that use hydrodynamic lift (rather then neutral bouyancy) to 'fly' underwater, for which theroretically it would be no problem at all.

All military subs use HD lift - well SSN/SSBNs anyway. Below a certain depth they need propulsion or they sink. It was one of the contributors in the USS Thresher accident http://en.wikipedia.org/wiki/USS_Thresher_%28SSN-5...

In answer to your question OP, I doubt it for two reasons. First I'm 90% sure the ballast system would vent if the boat was inverted, and second, I'm not sure there is sufficient roll authority to stop the sub from rolling conning tower up (if the ballast tanks hadn't already vented).

[mcdjl]

rhinochopig said:

All military subs use HD lift - well SSN/SSBNs anyway. Below a certain depth they need propulsion or they sink. It was one of the contributors in the USS Thresher accident http://en.wikipedia.org/wiki/USS_Thresher_%28SSN-5...

In answer to your question OP, I doubt it for two reasons. First I'm 90% sure the ballast system would vent if the boat was inverted, and second, I'm not sure there is sufficient roll authority to stop the sub from rolling conning tower up (if the ballast tanks hadn't already vented).

Immelman turns!

[rhinochopig]

mcdjl said:

rhinochopig said:

All military subs use HD lift - well SSN/SSBNs anyway. Below a certain depth they need propulsion or they sink. It was one of the contributors in the USS Thresher accident http://en.wikipedia.org/wiki/USS_Thresher_%28SSN-5...

In answer to your question OP, I doubt it for two reasons. First I'm 90% sure the ballast system would vent if the boat was inverted, and second, I'm not sure there is sufficient roll authority to stop the sub from rolling conning tower up (if the ballast tanks hadn't already vented).

Immelman turns!

Have you ever seen a A380 do an Immleman

[mcdjl]

rhinochopig said:

Have you ever seen a A380 do an Immleman

is it on youtube.....?

[Simpo Two]

I doubt it has the ability to go over the top so it has no choice!

rhinochopig said:

I'm not sure there is sufficient roll authority to stop the sub from rolling conning tower up.

That would be a roll off the top not an Immelmann.

[daz3210]

Simpo Two said:

That would be a roll off the top not an Immelmann.

I thought that is basically what an immelman involved

[scubadude]

You might not want to (due to the mess/expense) do it in a military sub but there are plenty more submarine vehicles than what the navy has...

http://www.deepflight.com/ these boys might be a good start :-)

Of course you can loop the loop underwater (I've done it myself) on a DPV (not a sub to be fair) but close enough for the average man to afford one-
http://www.youtube.com/watch?v=PyCGtzrrezY&fea...
http://www.youtube.com/watch?v=3wikbuPvWJU

[Simpo Two]

daz3210 said:

I thought that is basically what an immelman involved

Immelmann is vertical to just before stationary, boot rudder, rotate round and dive - stall turn in fact. You come out low and fast not slow and high.

ETA: Seems we're both right: http://en.wikipedia.org/wiki/Immelmann_turn

[mrmr96]

simonrockman said:

If you could pull 1G you wouldn't even fall around inside.

Simon

2G's you mean?

[Simpo Two]

+0.1G would be enough

[rhinochopig]

Simpo Two said:

+0.1G would be enough

0G

[mrmr96]

Simpo Two said:

+0.1G would be enough

If you've 1g of centripetal force then you'd fall. You need >1g to overcome gravity when you're inverted, and hence keep you in your seat.

[Brother D]

Pretty sure not physically possible to maintain positive G at all points during the manouver.

Top speed (although classified) is around 60-70kmph

And most military subs are at least 350 feet long

So you would need to do a pretty tight radius to keep things from falling to the ceiling going over the top, and I wouldn't have thought it has the capability for the necessary change in the vertical vector component to achieve that.

[Simpo Two]

mrmr96 said:

If you've 1g of centripetal force then you'd fall. You need >1g to overcome gravity when you're inverted, and hence keep you in your seat.

I'm not sure whether one's G is what you actually experience, or whether you have to add +1 to everything. So if you are upside down, then a total force of... damn this is complicated!