We have some problems.

1. The fuses are, because of antenna aspect bias related to the target profile signal return and the size restrictions of vacuum tube technology (Love RAYTHEON, but even they couldn't make a 1943 thyratron that small) going to have to occupy the entire nose of your projected 40 mm rocket.        

2. That rocket is going to have to be FAST. Some kind of PBX mix, designed with a controlled geometry grain burn with a metallic salt as a booster, is necessary for the fast-burns and very high acceleration gammas you want. Those rockets will leave a dense smoke contrail when you ignite and launch them  using WW II propellants and chemistry.

3. The motor casings will be subject to gas pressures and sustained heat-load one would expect from a machine gun. AFAIK the Germans, Russians, and British copied each other and used the same kind of shrunk gun barrel over inner jacket solution to produce a motor casing tough enough for the burn candle pressures. Those made for thick walled 50/50, 60/40 or 70/30 fuel-oxidizer candle/casing ratio mass rocket motors and that was before you added the payload. Short and FAT in those thick wall cases was the desired geometry. That is a bad cylinder lift ratio for air to air missiles. In the case of the Germans when they could they used hypergolic fuel and oxidizer combos and they said to hell with solid fuel rocket motors.

4. The Americans had a devil worshiper Hell's Angel biker dude (before there were Hell's Angels) and an insane Hungarian; who both played with explosives games in their garages, and who went on to found JPL. It was the Hungarian madman, I think, who developed the modern thin-wall solid fuel rocket motors that almost everyone uses today by figuring out how to use the motor burn, itself, as a 'casing effect' to contain the pressures inside the candle's burn cavity. It was the biker dude who was crazy enough to test the Hungarian's math.*

 

* For those of  you interested, it was Theodore von Karman who was the mad Hungarian; and it was Jack Parsons, who later after the war blew himself up in his garage, who figured that one out.   

 

5. So before we can fit the fuse into the nose of our skinny three inch rocket, we need the skinny three inch rocket. 6. Then we have to figure out how to inert the fuse (calculate setbacks, design idiot proof arming gates and, decide what arming safe interval do we want [the time delays]: how do we, also, eliminate stray signal return from the environment, so that only that signal return we get from our intended FW 190 victim spikes in the circuit and initiates the detonation chain?). We then have to pack enough steel rods into the mid-body of our skinny rocket and design the shaped impelling charge to throw those rods out in a burst pattern that will rip through wing and fuselage to tear that Butcher Bird up. Near miss fragmentation will not give us an engine or pilot kill. We have to use structure kill to down the bird and hope we promote fire from hot metal strikes.

7. Then we have to design a rocket launch pod that will fair clean as possible either below a wing or in the NOSE of our fighter.

8. The prop wash has to be factored when we look at this rocket solution. Right now banks of launch rails at the outer wing of that Allied fighter seem like the most likely single engine fighter solution to avoid that tuebulence.

9. The biggest remaining problem besides paired salvo fire, all that smoke, and the fact that the Allied fighter pilot now has a huge drag penalty, as well as 250 to 500 kilograms of sensitive HE sitting on his wings; is that after he is out of rockets, then what does he do?

10. The modern solution for, out of missiles, is to use the gun her has and RUN for home, but we took that away from him to give him the fuel  to lug around the rockets. NO ENGINE POWER we left him to loft the added mass and drag of both rockets and guns with enough maneuver reserve to operate against a cannon armed German fighter.

 

You need something like the F7F to make this rocket idea work in WW II.

 

H.