[ww2] Ever smaller rockets for air fighting?

[tomo pauk]

The R4M was supposed to be the panacea among the air-fighting firepower, at least when reading some stuff on the net. Shortcoming, at least on the piston-enginedd A/C like a Fw 190, was that rockets were supposed to be outside of a small fighter, thus slowing it even more.
So, let's make the engines small enough so they can fit somewhere in the wings. How small a rocket should be, while still being effective? How many we would need per a fighter for a typical 1943-44 scenario?

 

[Shortround6]

The smallest air to air or air to ground rocket I have seen reference to is 37mm and I think it was made by Spain and/or Brazil (Avibras SBAT-37 in Brazil) the 70s or 80s?

51-57mm seems to be pretty common.

for anti bomber use you need to balance the warhead to killing the bomber with one hit which means you need something over 30mm, like 37-50mm.
Now can you get the speed you need from a WW II rocket motor? of acceptable size?

And you need a crap load of rockets to get one hit as their accuracy was a lot worse than guns.

And you need to either get rid of the exhaust from the launch tubes or use a two stage motor (ejection stage and then full power stage) which usually increases dispersion.

 

[Shortround6]

Rockets are very different than guns.
They are amazingly cheap in regards to the cost of a single rocket and launcher.
They are amazingly expensive in terms of the cost of the propellent needed to get the payload (warhead) to the target.

Germans were short of everything in 1944 and on. Maybe using cheap steel (and even wood trays) was worth the 4-6 times the cost of the propellent (or worse) per round fired?
If you are willing to accept a slow rocket (short range) you don't need as much propellent.

 

[wuzak]

As an aside, the trailer for the upcoming series Masters of the Air seems to portray a Werfer-Granate 21 rocket flying through a formation, maybe even hitting a B-17.

 

[GrauGeist]

The rocket itself, was fairly streamlined (it needed to by virtue of it's function), so I don't think it/they imposed a serious drag penalty.

It would be the mounts that would be more suspect. The FFAR and HVAR went through several styles of mounting, the rocket itself being 3.5 inches (83mm) in diameter for the FFAR and 5 inches (127mm) in diameter for the HVAR.

The R4M's mounting "tray" seemed to be a bit more streamlined than the launch tubes and mounting struts of the BR 21, though not by much.

 

[tomo pauk]

The smallest air to air or air to ground rocket I have seen reference to is 37mm and I think it was made by Spain and/or Brazil (Avibras SBAT-37 in Brazil) the 70s or 80s?

51-57mm seems to be pretty common.

Going with 37-40mm calibre rocket would've probably allowed for a Fw 190 to carry a sizable load of these within the wings, plus a number under the wings?

Rockets are very different than guns.
They are amazingly cheap in regards to the cost of a single rocket and launcher.
They are amazingly expensive in terms of the cost of the propellent needed to get the payload (warhead) to the target.

Perhaps use the Davis gun principle, to save on propellant? Granted, there is still a need for a cannon of sorts to be made (okay, not a biggie), however a host of barrels with rockets inside will impose an even greater drag penalty.
Go for sort of a mechanized Davis gun, so it can be tucked in the wing?

Obviously I'm mostyl thinking aloud, unguided rockets for air fighting were rarely the interest of my attention.

The rocket itself, was fairly streamlined (it needed to by virtue of it's function), so I don't think it/they imposed a serious drag penalty.

It would be the mounts that would be more suspect. The FFAR and HVAR went through several styles of mounting, the rocket itself being 3.5 inches (83mm) in diameter for the FFAR and 5 inches (127mm) in diameter for the HVAR.

Hanging a few dozens of 55mm rockets under the wing, along with their launchers, was probably not a big deal on the Me 262, but it might get the Fw 190s and Bf 109s in the trouble?

 

[GrauGeist]

anging a few dozens of 55mm rockets under the wing, along with their launchers, was probably not a big deal on the Me 262, but it might get the Fw 190s and Bf 109s in the trouble?

By late war, the Germans were hard-pressed for time, so there wasn't much time to spend on designing a better rack system for the R4M, but I would imagine that a system that partially embedded the rockets or at least didn't present such a large frontal area would have worked on at least the Fw190. The Bf109 would have been limited to such an arrangement due to it's thin wing.

Here's the rack under an Me262's wing - that's alot of frontal area producing drag.

 

[z42]

What about some kind of belt-fed recoilless gun? Was something like that ever attempted? If you could keep the belt and belt feed motor inside the wing, and only the barrel protruding underneath, that would reduce drag?

And put a dual impact/time fuse, set the timer to something like 500(?) m, and if you're lucky shrapnel or blast from a near miss might still bring down or at least damage a bomber?

 

[tomo pauk]

What about some kind of belt-fed recoilless gun? Was something like that ever attempted? If you could keep the belt and belt feed motor inside the wing, and only the barrel protruding underneath, that would reduce drag?

Back in ww2, MK.115.
In the 1990s, the RMK 30.

And put a dual impact/time fuse, set the timer to something like 500(?) m, and if you're lucky shrapnel or blast from a near miss might still bring down or at least damage a bomber?

Would not be funny on the recipient end, I guess, especially when the bigger warheads start exploding, like the 50mm and bigger.

 

[Shortround6]

A few points.

It is one thing to make a big hole in the spar's to fit one big barrel/launch tube through.
It may be something else fitting 8-12 large holes in each wing

Trying to arrange the rear of the tube/s to go over the flaps may be hard. You want the tubes angled up a bit.
You do NOT want the tubes in line with ailerons or you may score 'own goals" where the back blast damages or removes the ailerons if the plane is banking.
Likewise you want to try and keep the flaps clear (a lot easier with the underwing set ups.)

Rocket rails/racks/tubes can use a much higher rate of fire than a magazine fed rocket launcher. Each rail/rack/tube is a single shot unit and all you need to do is wire up the electrical firing system to give the firing rate you want.
The magazine fed (or belt or ???) rocket launcher has to be able to move heavy rockets a fair distance to get the following shots into the tube. 5 20mm shells take up the same "room" as 2 50mm rockets and the 50m rockets are much much heavier. And the rocket feed has to stop and start. (so do belt feed machine guns but even a 50mm rocket is heavier than 150 rounds of MG ammo.

The time fuse rockets may work on clusters/banks of rails/racks/tube but the number rounds that can be fired from a single (or pair, one in each wing) rocket guns is going to be limited and the range is going to vary a lot between shots.

 

[tomo pauk]

It is one thing to make a big hole in the spar's to fit one big barrel/launch tube through.
It may be something else fitting 8-12 large holes in each wing

Spar is usually a cantilever item, that has strong high beam and a strong low beam, with connecting members between the two, like it can be discerned on the Spitfire's wing here. The Fw 190 was tested with 6 internal launchers for the sizable rockets (RZ65), in this case the longitudinal stringers probably helped a lot with the integrity of the 190s' wing.
We can see here that Tank and his team were not afraid of fitting 8 large holes in the spar as-is. (yes, these hole there will not be usable for the launcher tubes, but still)

rying to arrange the rear of the tube/s to go over the flaps may be hard. You want the tubes angled up a bit.
You do NOT want the tubes in line with ailerons or you may score 'own goals" where the back blast damages or removes the ailerons if the plane is banking.
Likewise you want to try and keep the flaps clear (a lot easier with the underwing set ups.)

Will probably need a Y-shaped plumbing, to vent both over and under the wing.

Rocket rails/racks/tubes can use a much higher rate of fire than a magazine fed rocket launcher. Each rail/rack/tube is a single shot unit and all you need to do is wire up the electrical firing system to give the firing rate you want.

Yes, the external launchers were pretty simple and efficient (as they are today), provided one has the performance surplus?

The magazine fed (or belt or ???) rocket launcher has to be able to move heavy rockets a fair distance to get the following shots into the tube. 5 20mm shells take up the same "room" as 2 50mm rockets and the 50m rockets are much much heavier. And the rocket feed has to stop and start. (so do belt feed machine guns but even a 50mm rocket is heavier than 150 rounds of MG ammo.

Germans, Japanese and Soviets were experimenting with 45-57mm automatic airborne cannons, so the high-speed feed was also also workable with the rockets IMO. RoF was good; size, weight and recoil less so.

 

[tomo pauk]

A few details of the Mk 115, vs. the 'medium power' MK 112 (a very short barreled weapon), vs. the 5cm 'full power' gun (MK 214A); ammo with Mine shell:

	MK 115 (recoiless)	MK 112 ('reduced' power)	MK 214A (full power) (Wikipedia)
shell weight, kg	1.48	1.48	1.52-1.56
weight of explosive, g	420	420	335
propellant weight, g	500	215	860
MV, m/s	600	600	920
weight of the gun, kg	190	275	718
RoF, rd/min	300	300	150

Shell used was probably the same in the 112 and 115? Barrel length of 1050mm for the 'classic' 112, and 1200 mm for the recoiless 115; the 214A have had almost the triple length of the barrel.
What all of this means? The 214A will not fit on anything 1-engined LW actually had (might've pitted on a pusher?). The 112 sould be an easy fit on something 2-engined, and by the skin of the teeth on the Ta 152C, but I don't give it too much of hope.
The 115 is probably the only option for the Fw 190/Ta 152 of the weapons listed, wing installation, but it will need real jump in horsepower and removal of other guns to make this fly when escorts are to be expected?
The lack of in-between weapon of 5-5.5cm, that might've been doing ~750 m/s, do 250 rd/min and weight perhaps 400 kg cann be seen, eg. fit two of the such on the Me 262 instead of one 214A or BK 5?

There was also lack of 37mm weapons for air fighting. Yes, no 1-shot-1-kill of the B-17 like the 50mm were promising, but the weapon would've been much easier to retrofit on the existing fighters, especially on the 1-engined fighters. A recoiless 37mm might've fit within the wing of the Fw 190, the 50mm MK 115 - better not.
(a 'classic' might've fit as a motor-cannon; talk a weapon in-between the MK 108 and 112)

 

[Zmauky]

The Germans tried the RZ 65 in 1943 and gave up, and the Russians used the RS-82 instead of air-to-air (as it was intended) for land targets.
I would say that, with small rockets, the range was too short, and the accuracy was not very high.
The R4M could be fired at a safe distance on target, and the USAAF flew in large groups. If they were used en masse, that would have changed, and hitting even a four-engine target (even with a gyro-stabilized sight) is not easy.


And the installation of the RZ 65 bypassed messing with the wing spar(s) on the Me 109. The Messerschmitt avoided it, but it was not a problem for the Spanish and Czechs on the Buchon and Avia 199.

 

[Shortround6]

Part of the problem was that they could conceive rockets, they could build rockets. Actual rockets didn't meet expectations in speed/range or accuracy.
Rockets were improved during the 40s, the 50s, the 60s and later. The idea stayed the same, the implementation kept changing.

The other problem is that cheap and precision (accuracy) don't overlap very well.

And as the "Battle of Palmdale" showed unleashing hundreds (or thousands) of rockets over occupied German cities per attack was only slightly less dangerous than letting the bombers drop their bombs

 

[tomo pauk]

And as the "Battle of Palmdale" showed unleashing hundreds (or thousands) of rockets over occupied German cities per attack was only slightly less dangerous than letting the bombers drop their bombs

Germans were using untold quantities of explosive ammo, from 13 to 128mm + different rockets, in Reich defense. They probably knew a thing or two about making sure that the stuff that goes boom really goes boom.

 

[GrauGeist]

Germany did use Hexogen to good effect in their minengeschoß rounds.

 

[Shortround6]

Germans were using untold quantities of explosive ammo, from 13 to 128mm + different rockets, in Reich defense. They probably knew a thing or two about making sure that the stuff that goes boom really goes boom.

Battle of Palmdale was Aug 1956, rockets were peace time manufacture (quality control?)
They found 15 out of 208 fired unexploded which means 193 rockets exploded, some did hit the target glancing blows and did not explode.

Most cannon shells, both aircraft and AA have self destruct elements or components built in. Sometimes it is simple like a delay element (slow burn chemical) between the tracer and HE compartment, shell explodes after a certain time of flight. Sometimes (mainly AA shells) the fuse detonates at the max time setting. Sometimes it is the reduction in rotational speed (spin) that triggers the fuse. I am sure there are others.
I have no idea what the US was thinking or why they had such a failure, it was a miracle that people were not killed considering the amount of damage done. The Rockets had been in service for several years in several different aircraft and were being made by the tens of thousands. Some sort of massive failure. A failure rate of a few % may be acceptable.

There are a few problems with fusing/self destruction in such rockets. The Germans had used time of flight to self destruct in the big rockets but that gave them fixed range. When firing at a bomber formation with 21 cm rockets that may have worked. When using rockets that needed direct hits that doesn't work but you need a self destruct system that functions a bit past the max expected range.
And we are back the acceptable failure rate of the self destruct system of the German Rockets in 1944/45 German production.

Just about anybody who made AA shells from WW I on knew about needing self destruct elements.

The US had over 8 years of R & D on the Mighty Mouse rockets at the of the BoP. They had bet the survival of the US against atomic bombs on them while they worked on guided missiles.
They didn't work.
The radar aiming system didn't work (German don't have that problem)
The accuracy sucked, big time. (doubtful in the Germans were better in 1944/45)
The fuses didn't work in the American rockets ( graze hits did not detonate, Germans may have been much better?)
If the American rockets had a self destruct mechanism, it didn't work. (German SD System?)

Maybe if they actually hit things people would not blame the rockets on the destruction on the ground?

Maybe they had a really bad batch or rockets at Palmdale?

Sorry, while a lot of the German weapons did point the way to future it often took years of work by the US, Britain and France to turn them into workable weapons in the 1940s and 50s.
You could mount rockets of different types on different German Aircraft to try to stop the Allied bombers. Getting them to actually be more effective than guns is a different story.
Doesn't matter that the guns were not doing the job. Yes the Germans needed something more effective than the guns they had. The question is if the rockets could actually do the job.

 

[tomo pauk]

Sorry, while a lot of the German weapons did point the way to future it often took years of work by the US, Britain and France to turn them into workable weapons in the 1940s and 50s.

Sometimes it took Allied engineers years to make a product that German engineers made work within conditions of the ww2. That is not to say that all German engineers were cream of the crop and that Allied engineers were dumb, but disproves the notion that if Allied engineers were not managing it, their German counterparts will certainly not do the job.
Same as when we discuss the 1000+ rd/min Belgian HMGs - just because the Americans were not coming with a viable counterpart in the same time (1939/40), it does not automatically means that Belgian guns were somehow suspicious.

Yes, there were the instances when German engineers botched what they were doing.

You could mount rockets of different types on different German Aircraft to try to stop the Allied bombers. Getting them to actually be more effective than guns is a different story.
Doesn't matter that the guns were not doing the job. Yes the Germans needed something more effective than the guns they had. The question is if the rockets could actually do the job.

Germans certainly needed more effective guns than what they had.
They reckoned that a 50-55mm Mine shell (400+- grams of explosive) has 1-hit-1-kill ability. The R4M puts them in that ballpark, and any fighter - even a Bf 109 or He 162 - can carry 15-20 if these rockets, while it will take a Me 262 to carry a 50-55mm cannon without turning itself into a turkey.
Are the rockets ideal? Probably not, but also probably worthy of a look on them, as well as on the recoilless guns, both the existing and the ones that were feasible in the era.

 

[Shortround6]

Sometimes it took Allied engineers years to make a product that German engineers made work within conditions of the ww2. That is not to say that all German engineers were cream of the crop and that Allied engineers were dumb, but disproves the notion that if Allied engineers were not managing it, their German counterparts will certainly not do the job.
Same as when we discuss the 1000+ rd/min Belgian HMGs - just because the Americans were not coming with a viable counterpart in the same time (1939/40), it does not automatically means that Belgian guns were somehow suspicious.

There are several conditions we do not know that help define "worked".

The US wanted a certain number of jams/malfunctions per 1000 rounds in test. They wanted a certain number of broken part/s. per 1000 rounds and they wanted a certain gun life, how many rounds before the receiver could not be rebuilt. Perhaps they wanted too much?

But without knowing the conditions/parameters it is kind of hard to say if some of these weapons "worked" or not.
The US .50s didn't work in combat aircraft in 1940 and that was at 500-600rpm and almost 20 years.

I have no doubt the Belgians fired one or more test guns on the test range at 1000rpm+. What we do not know are all the little 'details'.

We also do not know the conditions of the barrel life of the Belgian 13.2mm machine gun. That comes in after they can get the gun to fire with acceptable reliability.

One of the 'classics' is that Germans "had" working wire guided missiles in WW II. Yes they fired several on test ranges. French started working on Developing the German missile in 1948. Took the Allies until until 1955 to actually put them into the field (US had purchased and tested 500 missiles in 1952-53).

Just getting the wires to unspool and not break over 1-2km of range most of the time turned out to be quite trick let alone all the rest of the problems.
Again, what sort of failure rate the Germans were willing to put up with may be different than what the NATO allies would put up with.
Also it turns out that the early NATO Anti-tank missiles were very over sold. What company salesmen/demonstrators with hundreds of rounds fired could do turned out to quite different than what regular troops with only a few rounds of experience could do. There is a reason that the anti-tank missiles of today are 5-6th generation and it is not just the warheads/rocket motors.

And again you had the whole cold war thing going on and fears of thousands of soviet tanks overrunning western Europe so cheap/effective anti-tank weapons were a hot selling item, if they worked. And you had the US, Britain, France, West Germany, Sweden, Switzerland and perhaps a few others (or partnerships) so there was certainly a lot of R& D going into it (too much duplication?)

It is not a US vs Germany thing. It is that it took years for anybody ( Britain, France, West Germany, Sweden, Switzerland ???) to get some the German WW II wonder weapons to work, but perhaps in the 1950s they wanted a lower failure rate, or more accuracy or better basic performance?

They kept the wire but they changed the guidance system so that the missile rolled as they flew and they needed a gyro so the missile knew which was "up" so that the appropriate spoilers would be activated on the wings/control surfaces when the controller sent the signals down the wire. You also needed some sort of autopilot to control height.

 

[z42]

There are several conditions we do not know that help define "worked".

The US wanted a certain number of jams/malfunctions per 1000 rounds in test. They wanted a certain number of broken part/s. per 1000 rounds and they wanted a certain gun life, how many rounds before the receiver could not be rebuilt. Perhaps they wanted too much?

But without knowing the conditions/parameters it is kind of hard to say if some of these weapons "worked" or not.
The US .50s didn't work in combat aircraft in 1940 and that was at 500-600rpm and almost 20 years.

I have no doubt the Belgians fired one or more test guns on the test range at 1000rpm+. What we do not know are all the little 'details'.

We also do not know the conditions of the barrel life of the Belgian 13.2mm machine gun. That comes in after they can get the gun to fire with acceptable reliability.

The Finnish Air Force was AFAIU(?) the only combat user of the FN machine gun, in .50 BMG caliber (well, a domestic produced pirate copy of the Belgian one). Apparently they were happy enough about them that they did use them to replace AN/M2's on their fighters for increased firepower. Perhaps some of the forum members with better knowledge of FAF ( J Juha3 ?) can chime in with more details?

After WWII they tried to repurpose them for light ground-based AA but that wasn't successful, as the high rate of fire combined with lack of a slipstream for cooling very quickly led to overheating and cracked barrels.