The British assist the French in building an early warning system

Discussions on alternate history, including events up to 20 years before today. Hosted by Terry Duncan.
User avatar
T. A. Gardner
Member
Posts: 2878
Joined: 02 Feb 2006 00:23
Location: Arizona

The British assist the French in building an early warning system

Post by T. A. Gardner » 31 Mar 2022 07:05

What if in 1939, the British shared their development of the Chain Home system and associated fighter control system with the French? The French build a radar and control system similar to that of Britain's and it is in place prior to May 1940. The French system could be similar or use home grown equipment--yes the French were experimenting with radar too.

Would the French Air Force, using such a system be able to fight the Luftwaffe to a standstill? Could it have seriously reduced the effectiveness of the Luftwaffe's support of the Meuse leading to French ground forces stopping the crossings?

I'm not changing the available aircraft the French had other than possibly their having proper radios to use such a system where necessary.

Would this have made a significant difference?

Another point to consider: If France still fell, and the Germans captured some of this system, how would it impact their decisions in attacking Britain later in the year?

User avatar
wm
Member
Posts: 7157
Joined: 29 Dec 2006 20:11
Location: Poland

Re: The British assist the French in building an early warning system

Post by wm » 31 Mar 2022 11:30

Thanks to the Channel the British radar was able to deliver an ample warning.
In France, the Luftwaffe mostly operated near the frontlines so basically, no early warning was possible.

User avatar
Takao
Member
Posts: 3603
Joined: 10 Mar 2002 19:27
Location: Reading, Pa

Re: The British assist the French in building an early warning system

Post by Takao » 31 Mar 2022 16:55

Experimenting is not production. It took the British roughly a year to begin installation of the Chain Home radar sites. So, even if the British decide to give their top secret equipment to the French in May, 1939(Why they would decide to do so I have no idea), the first stations might just be becoming operational when the Germans overrun them.

And that does not include the time necessary to train the necessary personnel to operate and maintain the radar sites, nor those tasked with collecting & collating all the data coming in and doing something useful with it. Sure, the British can train French personnel in Britain, but they have their hands full training their own people to staff their growing network

User avatar
T. A. Gardner
Member
Posts: 2878
Joined: 02 Feb 2006 00:23
Location: Arizona

Re: The British assist the French in building an early warning system

Post by T. A. Gardner » 31 Mar 2022 17:59

Takao wrote:
31 Mar 2022 16:55
Experimenting is not production. It took the British roughly a year to begin installation of the Chain Home radar sites. So, even if the British decide to give their top secret equipment to the French in May, 1939(Why they would decide to do so I have no idea), the first stations might just be becoming operational when the Germans overrun them.

And that does not include the time necessary to train the necessary personnel to operate and maintain the radar sites, nor those tasked with collecting & collating all the data coming in and doing something useful with it. Sure, the British can train French personnel in Britain, but they have their hands full training their own people to staff their growing network
What I propose here is that Britain assisted the French with technical information allowing them to set up a radar line of their own prior to May 1940, as the British had. It doesn't matter if the French used similar radar sets or ones of their own design, in this scenario they had sufficient in service to cover their border with Germany and Belgium.
They have also set up a fighter direction system copying the British in that respect.

Would it have made a significant difference?

User avatar
T. A. Gardner
Member
Posts: 2878
Joined: 02 Feb 2006 00:23
Location: Arizona

Re: The British assist the French in building an early warning system

Post by T. A. Gardner » 31 Mar 2022 18:02

wm wrote:
31 Mar 2022 11:30
Thanks to the Channel the British radar was able to deliver an ample warning.
In France, the Luftwaffe mostly operated near the frontlines so basically, no early warning was possible.
This is not completely true. If the radar system could detect Luftwaffe aircraft climbing to altitude and then assembling in formation, like the British were able to do, then there is warning. It wouldn't be as much time as the British got, but it would be sufficient to scramble defensive fighters and get them ready to meet the incoming strike.

It takes time for a large formation of aircraft to take off, climb to altitude, then assemble into formation before heading to a target. That alone gives the French with radar an advanced warning of approaching enemy aircraft.

User avatar
Takao
Member
Posts: 3603
Joined: 10 Mar 2002 19:27
Location: Reading, Pa

Re: The British assist the French in building an early warning system

Post by Takao » 31 Mar 2022 19:07

T. A. Gardner wrote:
31 Mar 2022 17:59

What I propose here is that Britain assisted the French with technical information allowing them to set up a radar line of their own prior to May 1940, as the British had. It doesn't matter if the French used similar radar sets or ones of their own design, in this scenario they had sufficient in service to cover their border with Germany and Belgium.
They have also set up a fighter direction system copying the British in that respect.

Would it have made a significant difference?
This I know. Regretfully you specified the year as 1939. Which I see as insufficient to get any sets produced, personnel trained, and be fully operational. Let alone an entire network - which took the British the better part of 2 years to cover much less territory.

Even if the British gave the plans to the French, I don't see a French Chain Home being operational, much less effective, before France falls.

User avatar
wm
Member
Posts: 7157
Joined: 29 Dec 2006 20:11
Location: Poland

Re: The British assist the French in building an early warning system

Post by wm » 31 Mar 2022 19:45

T. A. Gardner wrote:
31 Mar 2022 18:02
It takes time for a large formation of aircraft to take off, climb to altitude, then assemble into formation before heading to a target. That alone gives the French with radar an advanced warning of approaching enemy aircraft.
Certainly but, as far as I know, they didn't use large formations for tactical purposes. It was a dozen or so Ju 87s per sortie at best.
And they needed, I don't know 20 minutes to reach the frontline, so it was ten minutes to intercept them in midflight and that over enemy territories.
When it was an hour (?) from France to London.

I think the French didn't need the British for anything. The hardware used by Chain Home, although seriously impressive, was relatively simple and not even especially modern. It was basically an old and dead-end technology even in 1939.
French Chain Home could have been built even in the early thirties assuming political will and unity were available and both weren't. The first working radar was demonstrated in 1904 after all.

btw Chain Home didn't work over land (because of its ground clutter) so the French needed to implement the much more modern German designs of Freya and its ilk.

User avatar
Takao
Member
Posts: 3603
Joined: 10 Mar 2002 19:27
Location: Reading, Pa

Re: The British assist the French in building an early warning system

Post by Takao » 01 Apr 2022 00:10

Actually, after some research...Mr. Gardner's What If is, well, history.
https://ieeexplore.ieee.org/stamp/stamp ... er=7909880
The British and French were cooperating beginning in 1939. However, the completion date...September, 1940.

Thanks to you Mr. Gardner, I learned something new. I never thought the British would hand over radar to the French.

User avatar
Loïc
Member
Posts: 1068
Joined: 14 Jun 2003 03:38
Location: Riom Auvergne & Bourbonnais France

Re: The British assist the French in building an early warning system

Post by Loïc » 01 Apr 2022 01:37

indeed...
https://atf40.1fr1.net/t1557-les-radars ... -francaise
Electromagnetic detection (DEM) formed a vertical electromagnetic barrier (transmitter and receiver radio stations) capable of detecting the passage of an airplane (disturbance of radio electric signals) without being able to give the altitude or the position of the device. This DEM dam was installed along the north-eastern border over a width of 120 km, known as the “watch line”. It was operated by a company of Air Force DEMs. Subsequently, the DEM dam was extended to the Alps sector but also to the protection of major ports such as Brest and Toulon. A DEM installation was sensitive in Tunisia.
Electromagnetic detection (radar) The principle of radar, very well known in France since 1934, only slightly inspired the various armies before its military application was discovered in England by the mission of Lieutenant Commander Ballande of the inspection general of the air defense in April 1939. Considered very superior to all that was done in France (which was at the very least exaggerated with regard to the apparatuses but very real with regard to their application) on British proposal, France decided to purchase the English system with the order dated May 14, 1939 of:
- 6 high power radar stations
- 47 mobile stations on trucks
- 128 headlamp driving devices
- 300 on-board radar devices to be mounted on aircraft with IFF identification
The set was intended for the three armies

In early January 1940, the organization of a long-range radar chain (CH equipment) was adopted. Pending its establishment and on a provisional basis, a chain of 12 field stations (MB equipment) was to be installed by April 15, 1940 at the latest by the RAF. French personnel replacing British personnel as they are trained. In April 1940, a Franco-British network of radars was in place or nearing completion in Le Havre and Reims (Note that Reims, an important communication hub, was carefully avoided by the Luftwaffe, whose aircrafts had not received for a mission to attack the city directly because its DCA/AAA was reputed to be particularly effective, thanks to the information transmitted directly by the Franco-British radar station). The French order could not be honored following the delays recorded by the British in delivering the equipment to us. However, several mobile stations were being delivered at the end of May 1940 to be immediately destroyed before the German advance. It should be noted that a few mobile stations were delivered to France at the end of 1939 for the training of personnel. MB type equipment was delivered for this purpose to the Air Force (Compagnie du Guet de l’Air) for the instruction of personnel supervised by officers trained in Great Britain. The internships lasted three months and began at the end of November 1939 under the direction of Captains Ramon and Revirieux. At the end of the course, the personnel were sent to the northeastern front to operate the dozen MB mobile equipment delivered to the French army (replacing the British personnel). On the other hand, specialists were sent to England to familiarize themselves with the high-power equipment of the CH type, the delivery of which to France was to take place in the last half of 1940.
Stéphane Ferrard

User avatar
wm
Member
Posts: 7157
Joined: 29 Dec 2006 20:11
Location: Poland

Re: The British assist the French in building an early warning system

Post by wm » 01 Apr 2022 05:19

Gregory Clark writes this in his "Deflating British Radar Myths of World War II"
As important as CH was to the defense of Britain, the true advantage for Fighter Command was in the Filter Room. The Filter Room played a key role. CH stations were not effective in resolving and locating targets as was a Freya-type radar which rotated and used a frequency five times higher.
The Filter Room helped to minimize the weaknesses of CH. It was able to collect, and resolve into a clear picture, what the actual threat was from the numerous overlapping radar plots reported from various stations and match fighter resources against the enemy.
The British had developed a lead over the Germans in the method in which they used radar information, but not in the equipment itself.
Radar was just a component of the air defense picture. Spotting reports and signals intelligence filled in the areas where radar could not see, aircraft over 120 miles away and behind the radar station. In many ways signals intelligence was just as valuable to the British as was CH radar.

Signals intelligence allowed radar to report the approach of aircraft which were already expected. CH was able to give a twenty-minute warning to the fighters to intercept their target, but the radar was not sensitive enough to resolve the number of aircraft or type.
German air communications were intercepted at British HF listening stations. Early in the war German fighters used HF radio telephony while the bombers used more traditional HF telegraph for communications.
From the interception of this traffic, the British could get up to a two-hour warning and detailed information on aircraft numbers, routes and identity of attacking formations.
That was against strategic bombing, i.e., large formations flying high over long distances.
But the battle of France was mostly tactical bombing, i.e., small formations flying low over short distances. As far as I know, during ww2 nobody was able to use radar successfully against tactical bombers.

User avatar
Takao
Member
Posts: 3603
Joined: 10 Mar 2002 19:27
Location: Reading, Pa

Re: The British assist the French in building an early warning system

Post by Takao » 01 Apr 2022 20:33

wm wrote:
01 Apr 2022 05:19
That was against strategic bombing, i.e., large formations flying high over long distances.
But the battle of France was mostly tactical bombing, i.e., small formations flying low over short distances. As far as I know, during ww2 nobody was able to use radar successfully against tactical bombers.
Not until much later in the war(early-mid 1944). When better radars were made mobile, and could be situated near the front lines.

User avatar
wm
Member
Posts: 7157
Joined: 29 Dec 2006 20:11
Location: Poland

Re: The British assist the French in building an early warning system

Post by wm » 01 Apr 2022 21:27

The British had mobile radars since 1939. In fact, several of them were abandoned at Dunkirk. It didn't do them much good.
British GL Mk. II radar
Image

User avatar
Takao
Member
Posts: 3603
Joined: 10 Mar 2002 19:27
Location: Reading, Pa

Re: The British assist the French in building an early warning system

Post by Takao » 01 Apr 2022 22:37

wm wrote:
01 Apr 2022 21:27
The British had mobile radars since 1939. In fact, several of them were abandoned at Dunkirk. It didn't do them much good.
British GL Mk. II radar
Image
That is a fire control radar...Not a search radar.

It was also not a very good radar

Nice try though.

User avatar
T. A. Gardner
Member
Posts: 2878
Joined: 02 Feb 2006 00:23
Location: Arizona

Re: The British assist the French in building an early warning system

Post by T. A. Gardner » 02 Apr 2022 04:33

The GL series were for gun laying (GL) and used with 3.7" batteries for fire control. They wouldn't do anything for a GCI system to control fighters. The GL Mk II was a rough analog of the Würtzberg radar.

The long rectangular antenna is the radar and it produces a narrow vertical beam. That gives bearing to the target. By lobe switching you get a rough altitude. The smaller antenna higher up is an IFF to ID friendly aircraft.

It's not a great FC radar, but it was better than nothing. The Japanese captured several sets in Malaya too.

User avatar
wm
Member
Posts: 7157
Joined: 29 Dec 2006 20:11
Location: Poland

Re: The British assist the French in building an early warning system

Post by wm » 02 Apr 2022 07:30

It was a radar and obviously could detect planes, so (modified or not) could have been used for any purpose.
The only problem was that mobile radars, because small, weren't that great, i.e., had limited range and detection capabilities.

Return to “What if”