Henschel GT 1200

[Justo Miranda]

Henschel GT 1200​

By the beginning of 1937, Dr Lorenz of Technisches Amt (Luftwaffe’s Technical Office) was sponsoring the Walter HWK RI-203 rocket engine that promised enormous power for its weight.

This engine used compressed air to force a weak concentration of mono-propellant hydrogen peroxide into a reaction chamber, lined with a paste catalyst, which instantly changes it into water and oxygen. The reaction is so violent that the water emerges as superheated steam, able to provide 350 kg thrust after accelerating in the venturi nozzle.

In 1941 Dr. Hellmuth Walter designed two rocket engines for torpedo propulsion that used different combinations of hydrogen peroxide and catalysts.

-The HWK RII-203, with 760 kg peak thrust, used hydrazine hydrate and potassium cuprocyanide.

-The HWK 109-501, with 1,000 kg peak thrust, used Dekalin and Z-Salz.

The Kriegsmarine was not interested in this type of torpedo because of its limited underwater range.

But the Luftwaffe considered this not to be a problem if the new propulsion system was used in torpedo gliders.

In 1942 Henschel developed two torpedo-rockets of 450 and 533 millimeters under the codename LT 1200. To launch them from aircraft, it was also necessary to develop three types of gliders under the codename GT 1200.

Henschel engineers decided to use wings, tail assembly and radio-guidance system of the Hs 294 missile.

After the torpedo hit the water surface, the wooden glider broke off igniting the rocket engine by means of one mechanical trigger valve.

The torpedo tailfins were designed to cool the combustion chamber (500 to 2,000ºC) using sea water.

The GT 1200 program was cancelled in mid-1943 due the explosive nature of hydrogen peroxide.

During the war hydrogen peroxide received the codename Aurol for ship propulsion, T-Stoff for aircraft and missile engines and Ingolin for torpedo propulsion (turbine and rocket).

Henschel GT 1200 Entwurf I technical data

Wingspan: 4,104 mm, length: 7,350 mm, height: 1,100 mm, wing area: 5.3 sq. m, torpedo diameter: 533 mm, torpedo weight: 1,295 kg, total weight: 1,800 kg, torpedo warhead: 330 kg H.E. with magnetic proximity fuse, air speed: 35 m/sec, underwater speed: 38 knots, drop speed: 360 km/h, drop height: 70 m, air range: 2,200 m, underwater range: 900 m, power plant: one Walter HWK RII-203 rocket motor with 760 kg peak thrust and 106 seconds of life, guidance system: FuG 203 Kehl III/FuG 203b Strassburg mounted in the detachable tail cone.

Henschel GT 1200 Entwurf II technical data

Wingspan: 3,400 mm, length: 5,570 mm, height: 1,100 mm, wing area: 5.3 sq. m, torpedo diameter: 450 mm, torpedo weight: 1,200 kg, total weight: 1,200 kg, torpedo warhead: 450 kg H.E. with magnetic proximity fuse, air speed: 40 m/sec, underwater speed: 40 knots, drop speed: 360 km/h, drop height: 70 m, air range: 4,400 m, underwater range: 1,200 m, power plant: one Walter HWK 109-501 rocket motor with 1,000 kg peak thrust, guidance system: FuG 203 Kehl III/FuG 203b Strassburg mounted in two nacelles in the leading edge of the wings.

The Henschel GT 1200 Entwurf III was a modification of Entwurf II with the radio-guidance system replaced by one infra-red homing seeker mounted under the torpedo warhead in a chin-shaped nacelle.

 

[Grzesio]

Once again - very comprehensive and informative text - but considering the number of strange things it includes, is it supported by any reliable sources of the era?
For example, I strongly doubt the fuselage of the "Entwurf I" came from the Hs 294 - first of all, the GT 1200 was designed earlier than the Hs 294, then the fuselages were barely similar - e.g. the Hs 294 fuselage had diameter greater by 90 mm than the GT 1200 "Entwurf I".

 

[Scott Kenny]

-The HWK RII-203, with 760 kg peak thrust, used hydrazine hydrate and potassium cuprocyanide.​

Huh, that's not just using HTP as the propellant, that's breaking HTP into 2xH2O and 1xO2 via catalyst and then using that oxygen to burn the hydrazine...

(and of course such pleasant chemicals to work with...)

 

[Justo Miranda]

Huh, that's not just using HTP as the propellant, that's breaking HTP into 2xH2O and 1xO2 via catalyst and then using that oxygen to burn the hydrazine...

(and of course such pleasant chemicals to work with...)

German scientists failed to master the destructive instability of H2O2 and were eventually forced to use dangerous acids such as rocket propellants.

 

[Grzesio]

I'm sorry, but they had no slightest problems with stable highly concentrated hydrogen peroxide as an oxidiser or a monofuel - for example it was widely used for Me 163 and RATO engines as well as fuel pump of the A-4 missile and was not exploding just like that on its own.
Use of RFNA as an oxidizer, save for its ability for long time storage in a fuelled missile, offers higher specific weight of propellants, resulting in higher specific impulse of the engine - and for example for that reason the alcohol/LOX combination used in the A-4 was not optimal as far as the range was concerned.

 

[Scott Kenny]

I'm sorry, but they had no slightest problems with stable highly concentrated hydrogen peroxide as an oxidiser or a monofuel - for example it was widely used for Me 163 and RATO engines as well as fuel pump of the A-4 missile and was not exploding just like that on its own.
Use of RFNA as an oxidizer, save for its ability for long time storage in a fuelled missile, offers higher specific weight of propellants, resulting in higher specific impulse of the engine - and for example for that reason the alcohol/LOX combination used in the A-4 was not optimal as far as the range was concerned.

High Test Peroxide is not stable.

 

[Grzesio]

I've never heard of any problems with T-Stoff instability.
What's more, when T-Stoff found in an A-4 wreck from Sarnaki was examined by Polish underground scientists and its composition was reported to Allied intelligence, the reply was, it was impossible, such high percentage hydrogen peroxide could not exist.

 

[Scott Kenny]

I've never heard of any problems with T-Stoff instability.
What's more, when T-Stoff found in an A-4 wreck from Sarnaki was examined by Polish underground scientists and its composition was reported to Allied intelligence, the reply was, it was impossible, such high percentage hydrogen peroxide could not exist.

https://www.science.org/content/blog-post/things-i-won-t-work-peroxide-peroxides

 

[Grzesio]

In 1942 Henschel developed two torpedo-rockets of 450 and 533 millimeters under the codename LT 1200.

So, ad rem. The torpedo for the GT 1200 missile was to be developed by Walter, not Henschel, in 1940 and was not designated as the LT 1200 (contrary to rocket torpedoes developed after 1942)

Henschel engineers decided to use wings, tail assembly and radio-guidance system of the Hs 294 missile.

Henschel had to develop the glider indeed, the Hs 294 missile however did not exist in 1940, so its components couldn't be used. What's more, the GT 1200 was not radio guided, it was originally to be only stabilized in pitch with DFS systems, although drawings dated 1942 show ailerons, so roll control was introduced - possibly (my guess) after unsuccessful tests on unguided gliding bombs around 1940.
Also the - probably - final design drawings from 1942 do not show the Hs 294 fuselage.

The GT 1200 program was cancelled in mid-1943 due the explosive nature of hydrogen peroxide.

Strangely, other weapons using T-Stoff were designed and used with no problems till the very end of the war.

Henschel GT 1200 Entwurf I technical data

Henschel GT 1200 Entwurf II technical data

The data don't match original drawings of three GT 1200 variants, for example all three (sometimes known under fictional postwar variants A, B and C) carried the same torpedo of 533 mm calibre and some 543 cm length, while their wingspan was 400 cm (as this was the greatest wingspan allowed for the GT 1200).

drop height: 70 m, air range: 4,400 m

How could a 1300 kg heavy unpowered missile cover 4400 m, dropped at 70 m height with 360 km/h velocity? It was demanded, the gliding angle had to be 1:5 - so the air range from 70 m was to be not greater than 350 m.