WW2 Engine Ground Attacks

[Nick_GParticipant @nick_g]

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I wonder if others could help with a little discussion I had today.

While chatting about the cannon and rocket ground strike attacks of WW2 performed by Tempests among other aircraft I mentioned that when the gun camera film showed quite often a sudden plume of steam erupting from the funnel it also meant the crew was dead.

Reasoning being that for it to do such in so violent a way it most probably meant that the superheater line had been hit. Thus the high pressure superheated steam would escape into the smokebox and out of the funnel. This steam would also be flooding back into and through the fire box and in to the cab and flash cooking the crew.

The other party seen to think that they would probably be OK providing they were not hit directly or indirectly by shrapnel.

Opinions please.

Nick

[Nick_GParticipant @nick_g]

[NJHParticipant @njh]

Hmmmm best not to think about it maybe…..

Norman

[SillyOldDufferModerator @sillyoldduffer]

Posted by Nick_G on 16/08/2017 16:21:47:

.

I wonder if others could help with a little discussion I had today.

… a sudden plume of steam erupting from the funnel it also meant the crew was dead.

…

Opinions please.

Nick

Not necessarily. You sometimes see the same thing when steam ships are attacked. On the command 'Abandon Ship' boilers are vented to stop them exploding as the ship floods, or otherwise in an engine room emergency.

I don't know if a steam locomotive has a similar facility, but deliberately venting the boiler whilst being shot up would reduce the danger of a boiler explosion. Also, drivers might have been told to blow off because a depressurised boiler would be easier to repair if it was punctured.

Dave

[Geoff TheasbyParticipant @geofftheasby]

One of the oft-repeated film clips from the attack on Pearl Harbour shows an intense jet of black smoke shooting from the funnel of a warship. I imagine that a bomb or torpedo has just exploded in the boiler room, and some of the blast went through the furnaces.

Geoff

[Nick_GParticipant @nick_g]

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Fair points Dave.

But if a superheater line is broken does it flood back into the cab.?

Nick

[BazyleParticipant @bazyle]

It wouldn't be a problem if the firedoor was closed. I expect the problem was understood and standing orders were to stop firing when attacked and probably if going slow (freight train speed) abandon ship. The driver is out of line of blast anyway, and both superheaters and tubes let go in normal service sometimes. However Fury the super super heated experiment did fail and kill one cab occupant but that steam was at 1500psi.

[Ian S CParticipant @iansc]

I,v seen the effect of a 60lb practice rocket, fired from a Vampire (same rocket, concrete head), it took the turret off of a Valentine tank on the firing range, imagine the power with an explosive head.

The 8 rockets on a Typhoon were the equivilent to the broadside of a 6" cruiser.

Ian S C

[Mick B1Participant @mickb1]

Posted by Ian S C on 17/08/2017 04:08:39:

The 8 rockets on a Typhoon were the equivilent to the broadside of a 6" cruiser.

Ian S C

More like a 4.7" destroyer for 60 lb rockets. 6" shells weighed around 100 lb.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Mick Burmeister 1 on 17/08/2017 09:53:25:

Posted by Ian S C on 17/08/2017 04:08:39:

The 8 rockets on a Typhoon were the equivilent to the broadside of a 6" cruiser.

Ian S C

More like a 4.7" destroyer for 60 lb rockets. 6" shells weighed around 100 lb.

I reckon Ian is right. If I remember correctly, the 6" cruiser comparison was made after a Typhoon mistakenly attacked a British Destroyer close to the French coast making it possible to assess the damage.

Rockets usually travel much faster than shells and impact energy is proportional to velocity squared. Also, the comparison with a 6" cruiser was with live warheads. A 6" shell is mostly steel with a relatively small charge of explosive inside. Weight for weight a rocket warhead contains a much higher percentage of explosive in a thin container, and it makes a much bigger bang when it hits something.

In modern times the effectiveness of Typhoon rockets has been challenged. They weren't very accurate. But I think the criticism misses the point. After learning in 1914-1918 that heavy guns create obstacles by chewing up the battlefield, the British Army developed the concept of 'Suppressive Fire'. It's aim was to disrupt and disable without causing deep damage that might delay one's own side. A few near misses from rocket firing aircraft were quite sufficient to disrupt a train or road convoy. Even if nothing was hit, it could take an hour or two to recover scattered and terrified personnel before the journey could be restarted. Several such attacks can gridlock an entire transport system causing days of chaos and multiple delays. The effect is suppressive rather than destructive, and none the less effective.

Dave

[Andrew TinsleyParticipant @andrewtinsley63637]

If you see steam coming from the funnel as a direct result of the impact, then I would not like to be the driver or fireman. Short answer is yes, they probably would be scalded, even if the firebox door was closed. I have been on the footplate when a blowback occurred, it wasn't a huge blowback, but even so, I had hair singed and burns to face and hands. The firebox door was almost closed , luckily for me.

As to the effectiveness of attacks on tanks. There was an analysis of hits claimed, in the Falaise p0cket.. Approximately half the claims made by Typhoons were found to be due to other causes. The trajectories of the rockets were not very reproducible.

Apart from hits, the Typhoons engaged in assisting the Americans defenders in the battle around Mortain just a week or so earlier They gave a huge boost to the hard pressed defenders and terrified the German troops. A good many of which were Marsch battalions (composed of doubtful troops).

The official history of that battle stated that the US troops managed to hold the German advance initially. Without the Typhoons they would not have been able to hold the line,if t he Germans had been able to deploy without interference.

Andrew.

[LambtonParticipant @lambton]

This extract from Wikipedia explains the catastrophic effect of any sudden damage to a working boiler.

If a large crack or other opening in the boiler vessel allows the internal pressure to drop very suddenly, the heat energy remaining in the water will cause even more of the liquid to flash into steam bubbles, which then rapidly displace the remaining liquid. The potential energy of the escaping steam and water are now transformed into work, just as they would have done in an engine; with enough force to peel back the material around the break, severely distorting the shape of the plate which was formerly held in place by stays, or self-supported by its original cylindrical shape. The rapid release of steam and water can provide a very potent blast, and cause great damage to surrounding property or personnel.

The rapidly expanding steam bubbles can also perform work by throwing large "slugs" of water inside the boiler in the direction of the opening, and at astonishing velocity. A fast-moving mass of water carries a great deal of kinetic energy (from the expanding steam), and in collision with the shell of the boiler results in a violent destructive effect. This can greatly enlarge the original rupture, or tear the shell in two.^[7]

[vintagengineerParticipant @vintagengineer]

When the pressure is released the remaining water will instantly boil and turn to steam. Just like taking the radiator cap off your car when the engine is very hot.

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