v2 reentry question

[Hoonte]

How did the v2 delivered their 'payload' to London.
Was the reentry temperature not high enough to 'melt' the nosecone or did they used somekind of heatshield?

[Jim]

The V2 was a short range missile and didn't even go into the hypersonic range

[Hoonte]

1,600 m/s is still an impressive speed. I don't know what kind of temperatures that wil give.. Short range has very little to do with it. (redstone) so maybe someone can inform me if 1,600 m/s (5760 km/h) should require a special nosecone or was this never an issue on the v2?

[Jim]

1,600 m/s is still an impressive speed. I don't know what kind of temperatures that wil give.. Short range has very little to do with it. (redstone) so maybe someone can inform me if 1,600 m/s (5760 km/h) should require a special nosecone or was this never an issue on the v2?

Range has everything to do with it.
Range is proportional to velocity, hence a short range bombardment missile is going to have relatively low velocity.  1600 m/s is under Mach 5 and it wasn't sustained for very long.  It didn't require a special nose cone.  It was the same material as the rest of the vehicle.

http://www.grc.nasa.gov/WWW/BGH/stagtmp.html

Anyways, what does Redstone have to do with it.  It was short range and it had low velocity for bombardment missile.  If you are trying to relate it to the Mercury capsules, then that is worng because those capsules didn't actually need a heat shield.

[Swatch]

And before anyone posts questioning Jim on what he meant by Mercury capsules didn't need heat shields...



See that mass of crap under the capsule?  That's the sub-orbital Mercury heatshieldsink.  That mess is a pile of beryllium oxide was once what handled the heat of reentry.  It was replaced on the orbital Mercury capsules with a standard ablator to handle the higher temps associated with orbital return.  That swap saved tons of weight but Mercury actually was considered for possible reusability with the heat sink on it (ironic huh?)... not that it was ever planned that way for manned flights.

Also... an interesting write up on it. 

http://www.zianet.com/leverett/mercury.htm

[Patchouli]

Many V2 warheads did explode during reentry the Germans dealt with this by switching to a rather insensitive explosive.

They used Amatol for the high explosive in the V2 which could handle some heat before becoming unstable the stuff would melt first before breaking down.
 
I got this from a book on the V2 by Steven Zaloga  called New Vanguard the V-2 Ballistic Missile 1942-52 it's a very good book on the subject.

BTW many later US warheads also used a beryllium heatsink type heat shield.

It's still technically a heat shield since it protects the warhead from the heat pulse that would other wise set off the HE or cook the electronics and it also radiates much of the heat back into the atmosphere.

The ablative heat shield might not have worked at all for sub orbital mercury missions since they might not have gotten hot enough for pyrolysis to occur.

Here's an entry that lists advantages and disadvantages of various thermo protection systems.

http://en.wikipedia.org/wiki/Atmospheric_reentry#Thermal_protection_systems