Bomb Hurel Turck 1938, the mother of the Henschel 293

Would you like to see the BHT 38 in games?
  • Yes
  • No

0 voters

[poll type=regular results=always chartType=bar]

On which plane(s) ?
  • On LeO 451 only
  • On Martin 175 only
  • On both
  • I don’t want to see BHT 38 in games

0 voters

Would you like to see in counter party (for the BHT 38 and maybe the HS 293) the addition of a Mas jammer on British and French ships in naval battle?
  • Yes as searchable modification
  • No
  • I don’t want to see BHT 38 in games

0 voters

Hello everyone, today I am going to tell you about a French hovering bomb from the Second World War (and not from the post-war period): the BHT 38.

Edit: This is a repost from the old forum

Part I: Missed start


The Hurel Turck 1938 bomb (BHT38) is intimately linked to the history of its creators, Maurice Hurel and Jean Turck

Our story begins in October 1938 when Maurice Hurel, director of CAMS (Chantiers Aéro-Maritime de la Seine : Seine aero-maritime shipyards) a company specializing in seaplanes, decides to create a flying bomb. For this he decided to contact the company Bougault, a company specializing in radio-electronic equipment. Within this company the engineer Jean Turck was enthusiastic about the project and proposed a new control system from an FM (Frequency Modulation) broadcasting invented 5years earliers by American enginner Edwin Amstrong.

Hurel approved this proposal and the two men developed a prototype aircraft which made its first flight at Vincenne to verify the feasibility of the project.

The results confirm their expectations and in the spring of 1939, a first order of BHT38 was ordered:Hurel took charge aerodynamic studies, Turck of guidance, and Caudron of the structure.

In November 1939 Turck was assigned to the Establishments of Roumefort in St Ouen, controlled by the DCCAN, as responsible for the machine. Completed at the end of April 1940, a dozen BHTs were lined up on the Fréjus runway, in order to check the proper functioning of the control surfaces, controlled by an operator installed on a nearby hill. The CEPA was therefore able to receive without problems in May a pre-series of these BHTs… only to have to destroy them shortly after, following the defeat in June, and throw them into the sea and this to prevent the Germans from recovering them.

The story could have ended there, but it didn’t: firstly because despite all the precautions taken by Turck to destroy and hide the proofs of the existence of his bomb from the Germans, the patent for the BHT remained in the hands of the Vichy government which soon followed the path of collaboration, and then because Hurel and Turck themselves had not said their last words…

Part II: Evasion


After the armistice of 1940, French aeronautical engineers retreated to the free zone and more precisely to Cannes. In order to ensure that the French would respect the terms of the armistice, the Germans instructed the Italian authorities to monitor French production in Cannes to ensure that the engineers would not manufacture warplanes. Indeed, if they were prohibited from producing war planes, nothing prohibited them from producing civilian planes.

However the Italian authorities took their job very seriously and to prevent an aircraft from escaping, they ordered that all tests be done in their presence. In addition, aircraft tanks had to be loaded to the bare minimum. Then, the take-off runways were guarded by Carabinieri and were covered with barbed wire outside the test periods. Finally, the taxiing tests on the take-off runway were carried out under the supervision of an AA turret whose servants had orders to fire in case a plane took off.

Among the prototype aircraft under construction, we can mention the presence of a twin-engine transport, the SO 90 Cassiopé.

It was on this plane that Hurel worked.

On August 13, 1943, Hurel got the Italians to take the SO 90 on the ground to check the controls. Accompanied by an Italian warrant officer, Hurel carried out the test, still under the supervision of the turret, but it turned out that the brakes were not working.

Taking the warrant officer as a witness, he went to ask the italian lieutenant in charge of the base for permission for another test the following week.

On August 16, , at 1:30 p.m., 9 individuals came to report to the only Italian sentry who was not in the canteen. They asked him to remove the barbed wire to replicate the previous test. This one, accustomed and thinking that there was an agreement, accepted.

Then the crew got back into the plane which rushed on the runway … and took off.

The servants of the turrets, in the middle of a siesta, were taken completely by surprise.

The Cassiopé passed over the lieutenant in charge of the runway who was sunbathing on a beach in Cannes. Stunned, the latter rushed onto the track still in a swimsuit to punish these French people who had deceived him. He didn’t have the chance because the Cassiope never came back.

Not knowing who to shout to between the sentry imploring the Madonna and the terrified AA servants, he resolved to warn the German hunt… half an hour late.

But who was the crew of this plane? You guess it. Hurel, the pilot, his three sons, two of his colleagues working in Cannes (Jean Weilet Gérard Allégret), General Jean Mollard, former military commander of Corsica as well as his son André both wanted by the Gestapo for acts of resistance and of course Jean Turck whom Hurel would not have left for anything in the world.

For nights, Hurel had filled the tanks of the Cassiopé in secret, and he had informed the local resistance of his escape by instructing them to warn the authorities of Algeria.

This first flight, arguably the most epic in history, was made with an open landing gear, lasted three hours and was anything but comfortable. The dashboard was only half assembled, Hurel had to go down several times (literally) to pull on the cables (all the controls were not installed).

The message of the resistance not having been received, the plane was almost shot down by the AA in Algeria and owed its survival only to the presence of mind of a French captain.

The plane finally landed at Phillipeville and its crew joined Free France.

Part III: Resistance


The first idea that came to Hurel and Turck when they joined the allies was to recreate the BHT.

But the British had other projects, they had been trying in vain for months to develop an effective jammer against the Fritz X and the arrival of Turck was an unexpected godsend.

They therefore asked the FFL to “lend” their engineer. The latter accepted and Jean Turck then found himself examining the controls of the Fritz X and the HS 293 unexploded. To his surprise, the control system of the Germans bombs was not only similar to those of the BHT, they were exactly the same. The only difference was the use of German materials. Obviously and despite all his efforts, he had not been able to destroy all the evidence of the existence of his bomb.

Some articles mention that the Vichy authorities exchanged the BHT38 plans for the return of French prisoners, others that the Germans discovered the plans themselves. Either way, the result was the same. With their BHT, Hurel and Turck had unwittingly given birth to two German wunderwaffens

So Turck got to work and explained to his English colleagues how to jam the bombs effectively.
The control signals of German guided bombs (and BHT 38 of course) were split into two pairs, one to transmit “up-down” commands, the other “right-left”. In each pair, the specific command transmitted was determined by the mutual duration of the two acoustic tones transmitted over a 200 millisecond interval. If the two tones had the same duration - each for 100 milliseconds - this corresponded to a “zero” signal, ie no command. If one of the tones sounded longer (and the other, respectively, less), then the receptors on board the bomb perceived the difference as a command to execute.

Part of BHT commands

This explains why the English who until now had tried to jam the German bombs by drowning them under a high concentration of signals had obtained very little convincing result.

Armed with this information, Truck helped them create the “Mas” jammer. This jammer at each transmission cycle, extended the tone corresponding to the “right” command. This led to the scrambled Hs.293s flying in an arc, continuously deviating to the right, and missing their targets.

Once the jammer was created, Hurel joined Turck and the two men went back to work. The BHT was not only reproduced but improved and tested on French Martin Maryland 167F at Boufariks (Algeria).

These first tests were particularly disappointing and revealed an unexpected problem : with the speed, the plane caused turbulence and very often the bomb remained attached to the plane. During a test, the bomb even hung on the tail of the Martin and the panicked pilot had to jerk the controls to get rid of it.

To solve this problem, it was decided, on the following carrier aircraft, the LeO 451 E8 (tail number F-BDGE n°493) provided by the government of Algiers to develop a release system that was original to say the least. The BHT 38 release system worked like a slingshot (or a catapult).

The BHT 38 was propelled in front of the nose of the aircraft (where the observer was).

Several tests on LeO 451 took place in Toulon in August 1944 only one month after the liberation of Provence.

However the BHT proved to be very difficult to control: although its controls worked perfectly and the radio signals were picked up without problems, the bomb tended to spin in strong winds. The rudder (reversed) tended to turn around and the bomb had difficulty following its trajectory.

In December 1945, after a series of test in a wind tunnel, it became clear that the problem was not related to specific technical faults, but was of a fundamental nature: the aerodynamics of the BHT-38 had been calculated without success. To fix the flaws, the entire bomb had to be completely redesigned.

Supreme irony, what ends the career of the BHT 38 is none other than… its own daughter, the HS 293.

Of a much better aerodynamic design, the German bomb seduced the French engineers who produced a dozen of them under the name of “Palombe”. It was even considered to produce it in series. This never happened, and for an equally ironic reason: thanks to Turck, everyone knew how to counter it. In August 1946, work on the BHT 38 was officially stopped.

Subsequently Turck worked on another flying bomb project on LeO 451, but that’s another story…
SNCASE SE.1500 Series, the early air-to-ground missile

Part IV: Characteristics


The BHT is a glide bomb without means of propulsion, hovering by gravity . She has an inverted tail in T

Weight (without explosives): 160 kg

Explosive weight: 50 and 100 kg charges were planned

Lengths: around 2 m

Diameter: 50cm

Wingspan: 2m

Practical range: Beyond 20 km, the bomb no longer receives signals from the remote control. Requires visual range though

Part V: Why add the BHT in game?


-100% French weapons

-To upgrade and (re)discover the Martin 175 and the LeO 451 from another angle

-Huge potential for future combined battle (including naval)

-Huge impact in flying bomb design of WWII

-Completely new weaponry for the French

-Who said the Germans were the only ones with their wunderwaffen?

-For the unique challenge of destroying other bombers with a catapult

-Equivalent to Fritz X and introductory argument to HS 293

-For the fun of course!!!



Pégase : revue de l'association des amis du musée de l'air | 2005-01-01 | Gallica

Pégase : revue de l'association des amis du musée de l'air | 2005-03-01 | Gallica

L'évasion du SO-90

Опытная управляемая бомба BHT-38 (Франция. 1939 год). - "Оружейная экзотика". (Нереализованные проекты, опытная и малоизвестная серийная военная техника) — LiveJournal

Беспроводные мушкетеры: управляемая авиабомба BHT-38 - fonzeppelin — LiveJournal

Here the links to other French gliding bombs on which I have already covered. I invite you to take a look if you haven’t already.

Finally I simply couldn’t finish this post on the BHT without showing you the link to the post of his German daughter. Here is the link to the Henschel 293. Here again I invite you to take a look.