The rocket plane whose cannon flew downward when fired upward

[230RN]

I've been looking at information regarding the World War II Messerschmitt Komet, the Me 163.

This was a rocket-powered fighter aircraft with outstanding flight characteristics (some of which attained speeds close to Mach 1), although as a fighter, it was actually limited in some respects because of those very flight characteristics.

https://en.wikipedia.org/wiki/Messerschmitt_Me_163_Komet

Most versions of it used a monopropellant fuel, T-Stoff, which decomposed rapidly into steam and oxygen and yielded the thrust to power the plane.

But in that article in wiki, there was a gun-related passage which I found very interesting --a 50mm cannon where the barrel got ejected from the aircraft as the projectile flew upward, which made it recoilless. And it was fired photoelectrically:

Although the Me 163 was a stable gun platform, it required excellent marksmanship to bring down an enemy bomber. The Komet was equipped with two 30 mm (1.18 inch) MK 108 cannons which had a relatively low muzzle velocity of 540 meters per second (1,207 mph, 1,944 km/h [1772ft/s -ed]), with the characteristic ballistic drop of such a weapon. The drop meant they were only accurate at short distance, and that it was almost impossible to hit a slow moving bomber when the Komet was traveling very fast. Four or five hits were typically needed to take down a B-17.
.............
A number of innovative solutions were implemented to ensure kills by less experienced pilots. The most promising was a unique weapon called the Sondergerät 500 Jägerfaust. This consisted of a series of single-shot, short-barreled 50 mm (2 inch) guns pointing upwards. Five were mounted in the wing roots on each side of the aircraft. The trigger was tied to a photocell in the upper surface of the aircraft, and when the Komet flew under the bomber, the resulting change in brightness caused by the underside of the aircraft could cause the rounds to be fired.  As each shell shot upwards, the disposable gun barrel that fired it was ejected downwards, thus making the weapon recoilless. It appears that this weapon was used in combat only once, resulting in the destruction of a Halifax bomber, although other sources say it was a Boeing B-17.[20][21][22]

And this was interesting and amusing, from the same article.  The plane could zoom up to 40,000 ft, then dive down through an allied bomber formation:

As the cockpit was unpressurized, the operational ceiling was limited by what the pilot could endure for several minutes while breathing oxygen from a mask, without losing consciousness. Pilots underwent altitude-chamber training to harden them against the rigors of operating in the thin air of the stratosphere without a pressure suit. Special low fiber diets were prepared for pilots, as gas in the gastrointestinal tract would expand rapidly during ascent.

I feel sorry for the first poor bastard who found this out.

Terry, 230RN

[HankB]

I remember reading a book about the Me-163 Komet in which the pilots really didn't like the T-stoff fuel and Z-stoff catalyst which were nastily corrosive to human flesh and had a tendency to leak into the cockpit . . .

[Brad Johnson]

Am I remembering correctly that one of the fuel components (don't remember which -stoff) was methanol and hydrazine?

Brad

[JonnyB]

I read somewhere that one component was hydrogen peroxide. Not the 3 percent stuff from Walgreen's, though...

[RocketMan]

I read somewhere that one component was hydrogen peroxide. Not the 3 percent stuff from Walgreen's, though...

Yep, 80-85% in T-stoff.  With a little water and some small amounts of stabilizers.  Nasty stuff.

[Northwoods]

Yep, 80-85% in T-stoff.  With a little water and some small amounts of stabilizers.  Nasty stuff.

Hypergolic with just about anything organic.  Including pilots.

Better to work with than ClF3O2.  But that's kind of a version of damning with faint praise.

[Scout26]

I feel sorry for the first poor bastard who found this out.

Terry, 230RN

Probably some poor Concentration Camp victim.   



IIRC, there's one Komet in Dayton at the USAF museum and one out at Dulles with the Air and Space Museum and one in the Imperial War museum in London.

Those are the three I've seen.   Fascinating aircraft.

[K Frame]

A number of Komets were also lost during landings when leftover fuel would splash around in the fuel tanks and... we... detonate.

The upward firing guns were used in both Japanese and German nightfighters, and was actually a concept first developed in World War I.

The Germans called the WWII assembly Schräge Musik. https://en.wikipedia.org/?title=Schr%C3%A4ge_Musik

This is the mount as it would have been used in an Me 110 nightfighter.



It came out of an earlier tactic in which pilots would dive under the bombers then pull up, and as the bomber passed overhead, fire into its belly.

[MechAg94]

From the description, was the cannon on the place a heavy caliber explosive shell?  It didn't sound like it would be a machine gun.

[K Frame]

The ones talked about in the original message were single shot and designed to be recoilless.

The ones I'm talking about were standard multi-shot and recoiled.

[230RN]

I think Mike Irwin was trying to show how upward-firing guns were arranged in prior practice, not that these were the specific Messerschmitt recoilless  single-shot cannons.

[K Frame]

Exactly.

[MechAg94]

The ones talked about in the original message were single shot and designed to be recoilless.

The ones I'm talking about were standard multi-shot and recoiled.

I realized you were talking about a different gun.  It was obviously a completely different system.  I am still curious about the cannon used on that jet.  Reminds me of those non-reloadable electrically fired guns (metal storm, I think).  Different times though.

The machine gun is interesting.  I hadn't realized that was done. 


"Didn't you get that memo?"

[230RN]

I am still curious about the cannon used on that jet.  Reminds me of those non-reloadable electrically fired guns (metal storm, I think).  Different times though.

Mechanically, it wouldn't be hard to do.

Think of a locked-breech action where after the barrel got unlocked, it would just come out the back and be discarded (downward).

Or, even more simply, think of a muzzleloading cannon where the cannon barrel was not restrained in its recoil and just got thrown backward (or in this case downward, out of the plane) as the shell went out the muzzle.  A little more weight required for that system, but it would work.  Kinda like a blowback action.

[AJ Dual]

The whole concept reminds me of an airborne Ontos...

[RocketMan]

The whole concept reminds me of an airborne Ontos...

It kinda does, doesn't it?  Those were some crazy machines.  I won't say whether I have actually seen one of those before.  Don't want to date myself.

Upon further reflection, it may have been a deactivated Ontos on display somewhere.  Yeah, that's it.

[230RN]

Had to look it up.

The Marines will take anything that goes bang and breaks things and people.

[RocketMan]

After further thinking about it, we did have a bunch of jeep-mounted 106s around the motor pool.  Got to see those torched off a few times on the range.
This further thinking stuff is hurting my brain.

[K Frame]

The Marines made good use of recoilless rifles in Vietnam. They were apparently especially useful during the siege of Hue, where the streets in the old city were a big impediment to getting heavy weapons into places where they were needed.

Ah, here we go. A picture from Wikipedia showing Marines using an M40 during the battle for Hue

[230RN]

http://farm4.staticflickr.com/3818/9082025580_b30d028fc6_o.jpg

[MechAg94]

http://farm4.staticflickr.com/3818/9082025580_b30d028fc6_o.jpg

I can't see the driver's seat so I assume it is offset to the other side for balance.

What is the concussion effect on the gun crew for those things?

[roo_ster]

I can't see the driver's seat so I assume it is offset to the other side for balance.

What is the concussion effect on the gun crew for those things?

1. Froggie recoilless rifle did not fire mounted.  Really not a bad idea, if upgraded into an off road motorcycle.  But, I always like the idea of bicycle and motorcycle-mounted infantry.

2. Recoilless rifles have wicked muzzle blast/concussion relative to a rocket of similar diameter.  And best make sure back blast area is clear.

[230RN]

I am told that the backblast nozzles for those things were subject to gas-cutting wear, at least in the originals.

So they made the nozzles undersized from the factory so they had some recoil at first.  As the gas cutting proceeded, there came a point where recoil was neutral.  Then, as more wear occurred, they would start to pull forward.  The implications for the Vespa's speed are obvious. :) :)

The nozzles were replaceable, so if they got to pull forward too much, they could replace them with factory nozzles.  (The nozzles were also tilted slightly to counteract the angular recoil of the rifling.)

Source: "Hatcher's Notebook," pp 273-278, "Colonel Studler's idea,"  with illustrations.

I doubt this concept applied to the Messerschmitt guns, since one would want the gun itself to be ejected from the plane instead of staying in one place.  However, that's just a guess.  I'm having trouble finding out exactly how those Me 163 guns worked.

The "simplest" idea I could think of was a careful balance between the weight of the gun itself + the weight and MV of the projectile (MV need not be very high in this application) + some sort of friction device to hold the gun in place in flight.  (Not to mention an unlinking system for the firing mechanism.)

But, knowing the Germans, it was probably more technical than that.

Terry

More:
http://images.info.com/cannon%20on%20vespa?qcat=images&r_cop=xxx&qkw=cannon+on+vespa
(I love the red muzzle cap on some of those... like the red cap required on Airsoft guns!  LOL  Of course, it was probably just a warning device, like the red flag required on stuff hanging out too far from the back of your pickup.)

[Scout26]

The Marines made good use of recoilless rifles in Vietnam. They were apparently especially useful during the siege of Hue, where the streets in the old city were a big impediment to getting heavy weapons into places where they were needed.

Ah, here we go. A picture from Wikipedia showing Marines using an M40 during the battle for Hue

What made Hue a bloody house to house slugfest, was the Prohibition on Artillery and CAS.   So the Marines resorted to using Recoiless Rifles and then mortars

[Harold Tuttle]

I have a Ballentine book series that featured Nazi technology
German Secret Weapons, Blue Print for Mars

The Natter was a dangerous ride

https://en.m.wikipedia.org/wiki/Bachem_Ba_349