Fokker D.XXI projets and derivatives

[lucamax]

Dear Arjen,
thank you for your help!
Best regards.
--
Lucamax

Dear friends,
I read about a Fokker D.XXI modified by spanish republican forces with a Shvetstov M-25 engine: have you more info about that?
According to the book "Aircraft of the Spanish Civil War - Gerald Howson", it was tested by Mario Palacios in the presence of the Gen Emilio Herrera.
Thanks a lot.
P.S. Merry Christmas to all!
--
Lucamax

The Shvetsov M-25 was a licence-built Wright R-1820 Cyclone. The Spanish Hispano-Suiza plant also had a licence to build R-1820s as the H-S 9V.

I have had a look at the appropriate chapter in Fokker D.21 - Fokkers laatste eenmotorige jager by Peter de Jong, Violaero 2012. This is what I found.

In 1937, Fokker and the Spanish Republic had arranged for licence-production in Spain of 25 C.10 scouts and 50 D.21 fighters. Fokker's head office in Amsterdam had made drawings for an R-1820-powered D.21 as part of this deal, presumably because of the availability of licence-built R-1820s. Peter de Jong writes that the single Spanish D.21 was probably assembled from locally made parts, so this was not a matter of an existing aircraft modified to accept the R-1820. It was a new build R-1820-/M-25-powered aircraft, with drawings supplied by Fokker.

The Spanish Fokkers were to be built in the Hispano-Suiza factory in Guadalajara, near Madrid. However, with the Civil War breaking out, the Spanish Republic moved all of Hispano-Suiza's and AISA's work force and machinery to La Rabasa airfield near Alicante. Both companies were nationalised in June 1937, with AISA becoming SAF-1 and H-S becoming SAF-5 - SAF being the Spanish acronym for Aeronautical Maintenance and Production Facility. The two facilities were then merged into SAF-15, under commandante Andrés Pitarch. The same facility also made Polikarpov I-16s, production of which took precedence over the Fokkers. At some time in 1937, La Rabasa was bombed by the Nationalists. Damage was more psychological than physical, but it was decided anyway to move production to the surrounding villages. The D.21 found a home in the Monasterio de la Santa Faz, which had been cleared of its population by the Republic - it had a problematic relation with the Spanish Roman Catholic Church which tended to side with the Nationalists.
De Jong writes the Spanish D.21s were to use Soviet equipment: four 7.62mm ShKAS machine guns and a Shvetsov M-25. De Jong writes it is unclear which engine was fitted in the D.21 when it rolled out of the monastry in August 1938: M-25 or R-1820. Test flights were conducted in October 1938, from Los Alcazáres-El Carmoli airfield. The pilot was Mariano Palacios Palomar, chief-instructor of the airfield's flying school. The aircraft carried the registration CF-001.

 

[hesham]

From Ali Nuove 5/1960,

and here is the translate;

above,on the left an original Dutch device of the former copies handed over to Finland,
of which he carries the insignia; on the right a similar Finnish construction device, equipped with
the engine "Mercury", the profiles we publish below are of some construed versions (those in black),
and of other versions studied but not realized (the clear ones); as you can see, several projects
intended for European aviation included the adoption of the retractile carriage, and some of the
engines with in-line cylinders.

 

[tallguy]

Does anyone have any info on the fate of the 50 Dxxis being built in Spain? Any data on performance w/1820?

 

[Apophenia]

Does anyone have any info on the fate of the 50 Dxxis being built in Spain? Any data on performance w/1820?

Not really. It seems that only the one, Shvetsov-powered Hispano Aviación D.XXI was completed. The rest would have been semi-finished airframes at SAF-15* - aka Aeronautica Industrial S.A. (AISA) - at Alicante (La Rabasa). Some of those components were incorporated into the post-Civil War Hispano Aviación HS-42 advanced trainer.

______________________________________

* I'm puzzled by the numbering of the Servicio de Aviación y Fabricación plants. Arjen lists "AISA becoming SAF-1 and H-S becoming SAF-5"
-- https://www.secretprojects.co.uk/threads/fokker-d-xxi-projets-and-derivatives.3514/#post-342710

According to the blog Vestigios de la Guerra Civil Española (Aeródromo de Rabasa article), Hispano Aviación (and other Hispano-Suiza manufacturing) was located at Guadalajara in SAF-1. AISA was at La Rabasa was SAF-15. At some point, Hispano and AISA plants were combined as SAF 1/15. I'm not sure when that was meant to happen but, since AISA was building the D.XXIs for Hispano Aviación, 1939 makes sense.
-- https://vestigiosdelaguerracivil.blogspot.com/2014/06/aerodromo-de-rabasa_22.html

 

[Arjen]

Does anyone have any info on the fate of the 50 Dxxis being built in Spain? Any data on performance w/1820?

See replies #38 and #41 in this thread.

 

[tallguy]

Does anyone have any info on the fate of the 50 Dxxis being built in Spain? Any data on performance w/1820?

See replies #38 and #41 in this thread.

 

[tallguy]

Neither has any performance data or the production status of the other aircraft that I can see

 

[Arjen]

Just one of the intended fifty D.21s was built in Spain, no other. That should answer your query about production status. I can't help you with performance data.

 

[tallguy]

Just one of the intended fifty D.21s was built in Spain, no other. That should answer your query about production status. I can't help you with performance data.

And yet I have read other sources that mention a number of them in various stages of construction

 

[Apophenia]

And yet I have read other sources that mention a number of them in various stages of construction

Yes, it is widely reported that various D.XXI components were found by the Nationalists after the fall of Alicante. As noted above, some of those components were incorporated into the postwar Hispano Aviación HS-42 trainer.

During the Civil War, the D.XXIs were already a low priority for the Republicans. Obviously, Franco's regime saw even less use for them.

As for performance, with a 750 hp engine, the Hispano D.XII was going to be an inferior performer to the Dutch or Finnish Mercury-powered examples (maybe more like the Danish pattern airframe?). If the sole Alicante prototype was inferior to the in-service I-16 type 10 (let alone later, more powerful Polikarpovs), it is unlikely that the Republicans would have bothered compiling much performance data.

 

[Moncho]

Illustration by J. Cuny.
Possible profile of the Spanish Fokker D.XXI modified and manufactured under license at the SAF-15 in La Rabassa, Alicante (SAF: Servicio de Aviación y Fabricación/ Aviation and Manufacturing Service, technical organization in charge of manufacturing and maintaining the FARE's aerial equipment, and in charge of the assembly of several Polikarpov I-15, I-16 Type 10, Fokker C.X and Fokker D.XXI).
It has a Soviet Shvetstov M-25 engine installed (the same as the I-15 and I-16; Soviet version of the Wright Cyclone with 9 cylinders and 725 hp) and was armed with four Shkas machine guns from the same origin.

Colour profile by Julio López Caeiro.
Spanish Fokker D.XXI with a Soviet Shvetstov M-25 engine and armed with four Shkas machine guns.

 

[GTX]

FokkerD21

With your support we keep the Fokker D.21 229 flying and so we keep history alive!!!

www.fokkerd21.com

 

[Stovepipe]

Those clever Finns managed to install retractable undercarriage while retaining 90 percent of the original wing including the original main spar. The swept, inboard leading edge and underwing bulges are the only aerodynamic modifications.

it looks like a copy of the Fiat G50 wing, with bulges for the wheels at the wing roots

 

[Apophenia]

...Colour profile by Julio López Caeiro...

It occurred to me that the Julio López Caeiro profile shows the D.XXI in Republican markings but retaining the original Bristol Mercury radial driving a three-blade, 2-pitch Ratier propeller. Obviously, that should be the Shvetsov M-25 (GAZ 19-licensed Wright R-1820 F3) and a Soviet propeller.

If we are talking about the sole completed Hispano Aviación D.XXI, then all bets are off. There doesn't seem to be any certainty as to whether it was powered by a Soviet M-25 or an American R-1820. If the latter, it may have been taken from an imported airframe and then who knows what kind of propeller was fitted.

For a hypothetical operational Hispano Aviación D.XXI - which Julio López Caeiro seems to be illustrating - then we can safely assume it to be powered by a Soviet Shvetsov. One problem is that all sources seem to refer to this engine simply as an 'M-25'. Does that mean M-25/M-25A model or later M-25V? The quoted power of 725 hp suggests the M-25V (the M-25/M-25A only produced ~625 hp). Either way, AFAIK, the appropriate Soviet airscrew would have been the 2-bladed, ground-adjustable VFSh-6 propeller. Since both I-15 and I-16 M-25s had interrupter gears for machine guns, I assume that the D.XXI would have had two ShKas cowl guns with another pair in the wings.

The Jean Cuny drawing shows no exhaust details. It would be tempting to show the I-16 type 5's style of exhaust ports cut into the cowling. Alas, there's no evidence for those. Cuny's drawing shows that no spinner was fitted. That makes sense - the Republicans usually removed their I-16's spinners to improve cooling. I also deleted the radio equipment (as per Cuny) but left on the pitot tube omitted from the Cuny drawing.

So, FWIW, I submit a reworked version of Julio López Caeiro's profile showing the appropriate powerplant and details made clear by the Cuny drawing.

 

[hesham]

From AE 95.

 

[Moncho]

Art by Carlos López Contreras.
Hi Apophenia, this painting may help a little.

 

[Apophenia]

Complete with exhaust port cut-outs. Nice!

 

[Stovepipe]

Wasnt there a plan to fit the Hispano 20mm cannon, along with nose guns to the D.XXI?

 

[GTX]

Wasnt there a plan to fit the Hispano 20mm cannon, along with nose guns to the D.XXI?

Not sure about that but the Danish ones did have under-wing 20 mm Madsen cannon pods:

 

[GTX]

And the finns tested 20mm Oerlikon cannon:

 

[Archibald]

Wasnt there a plan to fit the Hispano 20mm cannon, along with nose guns to the D.XXI?

Not sure about that but the Danish ones did have under-wing 20 mm Madsen cannon pods:

View attachment 679714View attachment 679715

A pity they couldn't put the guns into the wheels spats to save some drag. More generally, this fighter might have packed a lot of punch. 20 & 23 mm guns sounds like the near perfect caliber, between fire rates and destructive shells.

 

[ZacYates]

FokkerD21

With your support we keep the Fokker D.21 229 flying and so we keep history alive!!!

www.fokkerd21.com

And now she flies!

Fokker D.21 229 “PH-XXI” on Instagram: "“229 is rolling - Dan Griffith” The Dutch Flying Legend is back!!! What a great week we had!!! We did had some issues, but with our great team we worked very hard for many hours to get her airborne. Finna

332 likes, 8 comments - flyingfokkerd21 on June 19, 2022: "“229 is rolling - Dan Griffith” The Dutch Flying Legend is back!!! What a great week we had!!! We did had some issues, but with our great team we worked very hard for many hours to get her airborne. Finnaly Dan Griffith started the...

www.instagram.com

 

[NamedUser_]

FokkerD21

With your support we keep the Fokker D.21 229 flying and so we keep history alive!!!

www.fokkerd21.com

And now she flies!

Fokker D.21 229 “PH-XXI” on Instagram: "“229 is rolling - Dan Griffith” The Dutch Flying Legend is back!!! What a great week we had!!! We did had some issues, but with our great team we worked very hard for many hours to get her airborne. Finna

332 likes, 8 comments - flyingfokkerd21 on June 19, 2022: "“229 is rolling - Dan Griffith” The Dutch Flying Legend is back!!! What a great week we had!!! We did had some issues, but with our great team we worked very hard for many hours to get her airborne. Finnaly Dan Griffith started the...

www.instagram.com

What a beautiful sight to see.

 

[Justo Miranda]

On November 30,1939, the Soviets attacked the Finland eastern border with 450,000 men (20 divisions), 2,000 tanks, 2,050 cannons and 3,250 aircraft from types Polikarpov I-152, I-153, I-16, R-5, R-Z and U-2, Tupolev SB-2M103 and TB-3, Ilyushin DB-3 M and Beriev MBR-2.

The Finnish Armed Forces had 327,000 men (5 divisions), 20 tanks, 425 cannons, 2 armoured ships and 5 submarines. The Ilmavoimat strength was 135 aircrafts: thirty-six Fokker D.XXI, ten Bristol Bulldog Mk. IVA, seventeen Bristol Blenheim Mk. I, thirty-two Fokker C.X, seven Fokker C.VE, fourteen Blackburn Ripon IIF, four Junkers F.13, three de Havilland Moth, three V.L. Saaski and one V.L. Kotka.

Fokker D.XXI Mercury (418 kph)

​

Seven aircraft with 840 hp Bristol Mercury VII engines were acquired on 18 November 1937. Another fourteen were built under license by Valtion Lentokonetehdas (V.L.) in Tampere-Härmälä, powered by Bristol Mercury engines manufactured by P. Z. L. in Poland and delivered between November 1938 and March 1939. A second batch of 21 aircraft with Mercury engines, built in Tampere-Tampella, was delivered between March and July 1939.

Armament: a pair of 7.7 mm Vickers machine guns fitted in the front fuselage and two wing-mounted 7.7 mm Vickers.

Fokker D.XXI Wasp (434 kph)

​

On May 1939, fifty plans with 825 hp Pratt & Whitney R-1535-SB4-C Twin Wasp Junior American engines, were ordered to V.L.-Kuorevesi. They did not arrive in time to participate in the Winter War as they were delivered between January and June 1941. Less manoeuvrable than the Polikarpov fighters, the Fokker flew in 'finger four' formations and used 'zoom-and-climb' combat tactics. During the Winter War they shot down seventy-three SB-2M103, twenty-two DB-3M, two R-5, twelve I-16 and three I-152, losing twenty-three aircraft that were shot down in combat, one that was rammed by I-153, one by friendly antiaircraft artillery and forty-two due to crashes, sabotage and strafing.

Armament: four wing-mounted 7.7 mm Vickers machine guns.

Fokker D.XXI modified

​

Earlier, in 1939, the Finns had experimentally fitted two underwing 20 mm Oerlikon cannons in the Fokker FR-76.

On 29 January 1940 the FR-76 shoot down a Soviet DB-3M bomber with just 18 rounds, but the excessive weight limited its performances and the experiment was discontinued.

Another attempt to improve the outdated fighter consisted in installing a modified wing (the so-called E-wing) in the FR-121. It had more dihedral and was more tapered that the standard wing.

During flight tests it was found that the gun access panel blew off as a result of the air pressure in the gun bay.

Finally, two Fokkers were modified with a retractable landing gear: the FR-117 (Mercury) on 27 April 1941, and the FR-167 (Twin Wasp) on 2 March 1942. Both aircraft were later equipped with a fixed gear, and the whole idea was dropped because the speed improvement was only 15-37 kph, depending of altitude.

 

[hesham]

Fokker D. XXIV - single-seater fighter a development version of the D. XXI aircraft with retractable landing gear. Project only.

This D.24,was powered by one Bristol Preseus engine.

 

[Apophenia]

This D.24,was powered by one Bristol Preseus engine.

Fokker D.24 (aka Ontwerp 192) was to be powered by either an 880 hp Bristol Perseus X or a 1,080 hp Bristol Taurus III radial. To make up for these lower-powered engines, the D.24 was to have a slightly smaller airframe than the earlier D.22 (Ontwerp 150) project.

On Bailey's 2010 comment, the D.24 would have been very similar-looking to a D.XXI (albeit with a retractable main gear) but the former's design was not directly derived from the latter's airframe.

 

[riggerrob]

Not sure about that but the Danish ones did have under-wing 20 mm Madsen cannon pods:

View attachment 679714View attachment 679715

Breeches on Madsens were much bulkier than Hispano-Suiza cannons and they had more moving parts, but both proved reliable in combat.

 

[mat]

Not sure about that but the Danish ones did have under-wing 20 mm Madsen cannon pods:

Only one danish D.XXI (J-42) did have underwing 20 mm Madsen cannons. It was planned for the rest of the D.XXIs, as the D.XXIs were to be bomber-detroyers, when the Fokker G.1s would take over the job as defence fighters.