Dive bomber with Gerät 104

[Wurger]

Hi guys ,

I`ve just found this drawing in here:
http://www.ww2incolor.com/forum/showthread.php?t=4127&page=11

It is a rough sketch by Rheinmetall-Borsig on a carrier plane for their Gerät 104 Münchausen. The plan was to use it at a steep angle in order to penetrate the armoured deck of enemy battleships.
Concerning the aircraft depicted, it could well be just an aid to find the best mounting, or something already tought but not perfected. Notice the air brake, much like the one applied to the Do217. Other interesting features are the semirecessed engine mounts, high chord wings.
What do you think?

 

[Justo Miranda]

Ju 288 ?

 

[smurf]

I suppose it could be

 

[Wurger]

Hi Justo&Smurf ,

thanks for your replies. The Junkers Ju288 was to be the carrier for another odd weapon, the 280mm DuKa. Attached is a image of the early Ju 288 with it, taken from Nowarra.
But this sketch portrays a different scheme of an aircraft. The wing imbebbed engines were typical toughts of the pre-war years. The shoulder wing and the retractable gun are also interesting.
I recall a heavy long range ( 4 engined ) dive bomber from Tupolev designed about 1940. It was intended to bomb Scapa Flow from the USSR. This might have been the german solution to such a target.

 

[hesham]

My dear Wurger,


and from Luftfahrt magazine.

 

[Jemiba]

According to Manfred Griehl "Deutsche Flugzeugbewaffnung bis 1945" the Gerät 104, at least
in pre-prototype form was tested on the ground. For avoiding, what would have been a tremendous
recoild it used a counter weight fired backwards, so the whole gun actually consisted of two guns
mounted back-to-back. The test installation shown used an old Do 17Z. The test are said to have
been stopped after several shots, as the fuselage suffered severe blast damage.
In the mentioned book additionally a profile of a Do 217 carrying the Gerät 104 is shown.

 

[Rickshaw]

This weapon used a recoilless principle named after the first inventor of it - Commander Cleland Davis - who worked out the idea in 1910. Basically, by firing an equal sized mass to the rear at the same time as the shell was fired forwards, the recoil would be balanced out. His design connected two guns back to back, with the backwards-facing gun loaded with lead balls and grease of the same weight as the shell in the other gun, acting as a counter. Wikipedia has a reasonably good article on the idea.

It was used during WWI as an anti-Zeppelin and anti-Submarine/Ship weapon mounted on aircraft. It wasn't a great success and while those weapons were abandoned, the principle lived on, today being used in the Armbrust series of light-weight anti-tank weapons.

While I could imagine the shockwave from the rear venturi from a weapon the size of the Gerat 104 would have had rather unfortunate results on aircraft, if the Germans had been clever they should have avoided actual material damage from the counter-weight by making it from oil and sand. The rear fuselage might have had a bit of a scouring instead.

One way they could have gotten around the shockwave would have been to design the aircraft around the weapon, making it the central keel of the fuselage and extending the rear barrel to the extreme rear of the fuselage.

 

[joncarrfarrelly]

The full version of the Gërat 104 image from the old 1960s HE German Aiircraft Weapons book:

 

[Jemiba]

... Basically, by firing an equal sized mass to the rear at the same time as the shell was fired forwards, ..

In the mentioned book it is said, that the counter weight had a considerably lower mass, but was fired with
a bigger charge (probably to reduce overall weight of the installation ?)

Apart from the back blast, the front blast may have been an equally difficult problem, remebering, that the
Ju 88P with a 75 mm gun installation suffered from severe propeller vibrations, when firing its gun.

 

[Rickshaw]

... Basically, by firing an equal sized mass to the rear at the same time as the shell was fired forwards, ..

In the mentioned book it is said, that the counter weight had a considerably lower mass, but was fired with
a bigger charge (probably to reduce overall weight of the installation ?)

Basically to remove recoil you can either eject an equal mass in the reverse direction or a smaller mass at a higher velocity or eject a mass of gas, at a higher velocity. The Davis principle does the first two. "Conventional" recoilless rifles do the last.

Apart from the back blast, the front blast may have been an equally difficult problem, remebering, that the
Ju 88P with a 75 mm gun installation suffered from severe propeller vibrations, when firing its gun.

Possibly. The HS 129 also had problems when it tested the 75mm gun as well.

 

[Antonio]

A 75 mm gun was also tested in a Douglas B-18 belly mount.

 

[hesham]

Maybe the same concept.

 

[jcf]

Recreated post with the Gërat 104 illustration from the WE German Aircraft Weapons book.

 

[Wurger]

Can you please develop on the "HE German Aircraft Weapons" book? I couldn 't find it.

 

[jcf]

Can you please develop on the "HE German Aircraft Weapons" book? I couldn 't find it.

Sorry, that should’ve been WE not HE. :-[

On the cover:
German Aircraft Guns WWI - WWII
Aircraft Armament Series
Edward J. Hoffschmidt
WE Inc. Old Greenwich, Conn.
1969

Inside on the title page:
German Aircraft Guns and Cannon
E.J. Hoffschmidt

http://used.addall.com/SuperRare/RefineRare.fcgi?id=180909082107381388

A large percentage of the WWII material in the book is clearly reprints of Allied
WWII technical reports, interrogations and translated German documents. The
book has a good amount of info on the more oddball stuff including a couple of
R4M 55mm rocket automatic launchers, one magazine fed, the other belt fed.

Cheers, Jon

 

[Wurger]

Thanks, John, that title really sparked my curiosity. Actually those posted drawings I knew from Fritz Hahn's work but I will try to get it. Does it includes gunsights and gun stabilisation?

 

[jcf]

Thanks, John, that title really sparked my curiosity. Actually those posted drawings I knew from Fritz Hahn's work but I will try to get it. Does it includes gunsights and gun stabilisation?

The book is basically a catalog/compendium of the weapons and does not
include any info on gunsights etc.

 

[GWrecks]

Hi guys ,

I`ve just found this drawing in here:
http://www.ww2incolor.com/forum/showthread.php?t=4127&page=11

It is a rough sketch by Rheinmetall-Borsig on a carrier plane for their Gerät 104 Münchausen. The plan was to use it at a steep angle in order to penetrate the armoured deck of enemy battleships.
Concerning the aircraft depicted, it could well be just an aid to find the best mounting, or something already tought but not perfected. Notice the air brake, much like the one applied to the Do217. Other interesting features are the semirecessed engine mounts, high chord wings.
What do you think?

Back when I had a brief glance at this image I thought it was a He 111, but closer inspection implies otherwise. In that case, is this a new design or a redesign of some existing bomber? I know the Nazis would often modify their own aircraft to look much different from the original designs, so I don't imagine making extensive modification of an old design would be a far-off prospect. But I'm not sure.

 

[Jemiba]

I'm pretty sure, that it's just a generic sketch, somehow similar to some the then standard German
bombers, but not actually depicting one of them. Just have a look at those "engine nacelles".
That sketch was drawn by soemone from Rheinmetall, dealing with that weapon, but not with
aircraft.

 

[jcf]

I'm pretty sure, that it's just a generic sketch, somehow similar to some the then standard German
bombers, but not actually depicting one of them. Just have a look at those "engine nacelles".
That sketch was drawn by soemone from Rheinmetall, dealing with that weapon, but not with
aircraft.

Yep. Also I’m not aware of any existing Luftwaffe bomber aircraft of the period
that would be able to accomodate the retracted weapon in the fashion shown.