Dutch Fokker bomber and fighter projects from the late 30ties

[Silencer1]

Re: What was this Twin-Boom Fokker Project ?

Image redrawn in Inkscape, then exported as JPG.

Thank you, Arjen for your efforts and sharing of the result! Very clean and attractive.
I wonder, why vertical empennage doesn't presented on the frontal view - on the original drawing?

 

[Arjen]

I was tempted to add elements that I thought were missing, the vertical fins in the frontal view were missing in the original. In the end, I only added a trim tab to the starboard aileron.

I left out centre lines in what was, in some places, a sometimes vague and crowded drawing. I probably should not have omitted some of the barely visible lines. The three bomb silhouettes in the fuselage (no room there - is that in the engine pod?) I only realised were there when I had a very close look.
<edit> posted a modified image with added hinge and panel(?) lines.

 

[Hood]

Very nice work, you certainly have cleaned up the plan wonderfully and allowed us to see the detail clearly.
It still seems a very odd design, with just two DB600/601 engines it would have been quite slow but I guess overall bombload was superior to a single-fuselage twin-engine bomber (assuming both fuselages have a bomb bay).

 

[Arjen]

The space occupied by the original T.9's bomb bay accomodates the Jachtkruiser's main landing gear, I don't think any meaningful bomb load could be located in the remaining space. Some bombs might be carried in the Jachtkruiser's centre section, but text in the original image ('850L BENZ' - 850 litres of gasoline) indicates that space would have been used for fuel tanks. That leaves the space between the engines as a possible location for a bomb bay.

Some aspects of this concept may have been less than realistic.

 

[Silencer1]

The space occupied by the original T.9's bomb bay accomodates the Jachtkruiser's main landing gear, I don't think any meaningful bomb load could be located in the remaining space. Some bombs might be carried in the Jachtkruiser's centre section, but text in the original image ('850L BENZ' - 850 litres of gasoline) indicates that space would have been used for fuel tanks. That leaves the space between the engines as a possible location for a bomb bay.

Some aspects of this concept may have been less than realistic.

IMHO, as well as T.V and T.IX this design has been based on the idea of wing fuel tanks. There were plenty space inside wings, and volume in engine nacelle could be used interchangeable: by additional fuel tank (for interceptor) or for bombs (for bomber). How about such concept?
Anyway, the whole design look to me as quite exotic to be effective. At that time Fokker company has been really inspired by twin boomers, so "zwilling" configuration could be another attempt in same direction?

 

[Schneiderman]

I don't see any reason to doubt the drawing and that shows just two tanks of 850l each in the wing centre section either side of the engine nacelle.

I agree that the bomb load has to be in the central nacelle, and a load of three, what? 250Kg bombs? is low. With a crew of pilot, navigator and six gunners its difficult to envisage what mission it was intended for. The limited tranverse on the nose and lower guns is odd to, it leaves many undefended areas.

 

[Silencer1]

Your are right, Schneiderman! Thanks for correction

I'm inattentively seen the top view. Of course, the fuel tanks are located inside the wings.

I don't see any reason to doubt the drawing and that shows just two tanks of 850l each in the wing centre section either side of the engine nacelle.

I agree that the bomb load has to be in the central nacelle, and a load of three, what? 250Kg bombs? is low. With a crew of pilot, navigator and six gunners its difficult to envisage what mission it was intended for. The limited tranverse on the nose and lower guns is odd to, it leaves many undefended areas.

The whole design of this "air cruiser" seems quite unconventional. Bell "Airacuda" comes to my mind, as an example of concept, that has been interesting, but has been far from the reality. 6 gunners would be suitable for long range bomber, with enough power - but not for such aircraft.
Another example of designers' searches for perfection?
Just imagine this type has been built and put in mass production. Did it has any chances in air combat with Japanese aircraft? I doubt.

 

[Arjen]

The limited tranverse on the nose and lower guns is odd to, it leaves many undefended areas.

The nose seems to be modeled on the Fokker T.5's nose, which was originally intended as a jachtkruiser too. The nose gun's outline matches the T.5's Solothurn gun. This was a big weapon, its size alone would have restricted movement within the nose's limited space - hence the gun's limited traverse. The Solothurn was intended as a long-range offensive weapon, so limited traverse was less of an issue.
The T.9's belly gun installation, apparently adopted in this concept, likewise had limited gun traverse.
Complete T.5/T.9 images can be found here:
https://www.secretprojects.co.uk/forum/index.php/topic,15830.msg153899.html#msg153899

 

[lark]

The drawing made by Arjen is very close to th one produced
by Frits Gerdessen in Luchtvaart May 1998.

In all the sources I searched, never a 'Ontwerp' number was given for the cruiser aircraft.(design study only)

By the way , It seems that the info on the beeldbank-defensie.nl must be taken with a pinch of salt.
For exemple , drawing 25 or page 25 shows in fact a Koolhoven 1171 design it seems.
An early contender for the Fokker T.8W

The Fokker C.VIII was a 3 seat recce.aircraft for the LVA.Prototype only.first flight 17.3.1928
Of the Fokker C.VIIIW four intial designs were made ( two in Jan.27 ,one in Feb.27 and one in May 27)
The final version was a 3 seat,parasol wing aircraft for the MLD . First fight 15 Nov.1929.

 

[hesham]

Thank you my dear Lark,

and as I know,the C.VIIIA-W was given the drawing number 11150.

 

[hesham]

Here is a good artist drawing to D.23.

https://i.pinimg.com/originals/e0/23/0d/e0230de0cf5da5a5b0fd6717d08f2989.jpg

 

[hesham]

From L + K 23/1979,

the Fokker D.XXIII drawings with different engines.

 

[hesham]

Here is an artist drawing to Fokker D.XXXIII;

Fokker D-XXIII - Pagina 2

Een paar foto's. Leon 6058 6059 6060 6061

www.nederlandseluchtvaart.nl

 

[hesham]

in my files,

there was two Fokker Ontwerp 126 designs,we know the first,and the second was anther concept
of 1935,but maybe powered by more one engine ?.

 

[Apophenia]

in my files, there was two Fokker Ontwerp 126 designs, we know the first,and the second was anther concept of 1935, but maybe powered by more one engine ?.

Or maybe the 'other' Ontwerp 126 was about alternative engines for the driepersoons verkenner concept?

In Luchtvaartkennis 2012 nummer 3 (pp 87-90), Frits Gerdessen had an article 'Fokker driepersoons verkenner gaf aanleiding tot onenigheid'. In the Ontwerp 126 specs table box on page 90, Gerdessen quotes:

De motorkeuze is vrij. maar prestatieberekeningen worden verflangd voor Rolls Royce en Armstrong-Siddeley motoren.

Or, "The engine choice is flexible but performance calculations are needed for Rolls Royce and Armstrong-Siddeley engines."

No mention of exactly which alternative engines were being considered. As offered to the LVA, the Ontwerp 126 was powered by an 860 hp Hispano-Suiza 12Ydrs (as depicted in Tek nrs 35688 and 35689). Since the LVA also considered the Hawker Demon (for which Pander held the Dutch license) and the Fokker C.X tweepersoons verkenner was already flying, the 640 hp Kestrel V would seem a reasonable candidate for a 1935 Rolls-Royce engine. For Armstrong-Siddeley, likely they were considering the 760 hp Tiger VI 14-cylinder radial.

 

[Justo Miranda]

Fokker D-XXIII with different engines

 

[Justo Miranda]

Fokker D-XXI with different engines

 

[Michel Van]

let me see
Label as Fokker Ontwerp 152 is with DB 600H engine
and Fokker D.XXI H has a Roll-Royce Merlin

Ontwerp 150 must be with Bristol Hercules engine
while the Ontwerp 192 has a Pratt & Whitney R-1535 SB4C-G Twin Wasp Junior

I wonder with more powerful engines, would have the Fokker D.XXI H/ Ontwerp 152 be on same level like a P-51 or Me 109 ?

 

[hesham]

Or maybe the 'other' Ontwerp 126 was about alternative engines for the driepersoons verkenner concept?

No my dear Apophenia,

as I know it was anther design,even they didn't mention,it was monoplane ?.

 

[hesham]

In my files,

the Fokker F.XX was developed into a bomber,but it was remained a Project only,powered by only
two engines,there was a drawing to it also,but I don't have it.

 

[Apophenia]

Interesting. Frits Gerdessen made no mention of such a bomber project in his Luchtvaartkennis article, 'Vliegtuigontowerpen 1920-1944'. Considering all the aerodynamic problems encountered by the F.XX prototype, perhaps this bomber concept was dropped before it could receive an Ontwerpnummer?

 

[Grey Havoc]

It is possible.

 

[hesham]

Dear Apophenia,

also the Fokker F.VIII was developed in early 1925 as transport Project,maybe the configuration
differs a little from actually built ?.

 

[Apophenia]

also the Fokker F.VIII was developed in early 1925 as transport Project,maybe the configuration differs a little from actually built ?.

According to Paul van Weezepoel (dutch-aviation.nl), the 1925 F.VIII variant was that recently-discussed sesquiplane derivative of the 'convertible' F.V monoplane/biplane.

That said, the built F.VIII also began with a different configuration. When Reinhold Platz began this design for KLM in 1926, it was as a trimotor. It was only the availability of the more reliable Bristol Jupiter radial that allowed a switch to twin engines (with resulting reduction of fuselage vibration).

That raises a question: What were the planned powerplants for that 1926 three-engined F.VIII concept?

 

[lark]

In my files,

the Fokker F.XX was developed into a bomber,but it was remained a Project only,powered by only
two engines,there was a drawing to it also,but I don't have it.

 

[lark]

Hesham ,

Can you give us the source of the F.XX two engined bomber variant in your files?
I did a lot of search work in books and mag's about but without result....

 

[hesham]

My dear Lark,

the source maybe a Luchtvaartkennis magazine,but I will check.

 

[hesham]

Hi,

a drawing to Fokker T.V.

Fokker N.V. Nederlandsche Vliegtuigenfabriek T.V medium bomber plans: Fine No Binding (1937) 1st Edition | Morshead Books

1st Edition - No Binding - Fokker - 1937 - Condition: Fine - Fine - An original proposal document, describing the Fokker T.V. monoplane medium bomber design of 1936. Includes full specifications, and wire-line drawings. In exremely good condition, and extremely rare. The Fokker T-V bomber was...

www.abebooks.com

 

[hesham]

the Fokker F.XX was developed into a bomber,but it was remained a Project only,powered by only
two engines,there was a drawing to it also,but I don't have it.

The source maybe was this, Copies of original Fokker drawings and documents,I don't know what was it,a report or museum documents ?.

 

[Gjalt]

Fokker D-XXI with different engines

I don't think these drawings represent the designs, they look like just done up D.XXI whit a different engine, ontwerp 150/151 where enterly new desins (see the violaro book by De Jong)

 

[Gjalt]

So, any reason why Fokker was so left behind? The D.XXI was their best fielded fighter and it had fixed undercarriage. Was it because of lack of aluminium expertise, so they built wood- and fabric planes which didn't work well at high speeds? No advanced glues or Mosquito style mold built sandwich structures yet available at that point?

Money, lack of state supported funding was the main problem, also a small market, Fokker couldn't expect to receive orders of hunderds of orders off a single type from the Dutch goverment.

 

[hesham]

From Air Enthusiast 95.

 

[hesham]

What was this ?.

 

[Hardrada55]

See post #99....Oh, that's you also...and post #119.


additionally:

 

[riggerrob]

See post #99....Oh, that's you also...and post #119.


additionally: View attachment 679395

Looks like they swept outer wing panels to solve a balance problem.
This wing planform allows them to mount the rear engine far enough forward for balance.
A side effect is that both upper and lower gun turrets get clear lines of fire along the trailing edges of the outer wings.

 

[hesham]

Also from AE 95,

what was this ?.

 

[Apophenia]

Also from AE 95,

what was this ?.

In the numberless 1925-1929 Ontwerpen met een naam series, this 1929 concept was simply described as 'Luchtkruiser'.

-- https://www.secretprojects.co.uk/threads/fokker-ontwerp-numbers.2740/#post-327664

 

[hesham]

Here is a Fokker B.V and Ontwerp 115,also with T.VII.

 

[VictorXL188]

Thank you my dear Lark.

Here is a Fokker B.V and Ontwerp 115,also with T.VII.

Ontwerp 147 seems to be very like the postwar F.25

 

[Maveric]

Thank you my dear Lark.

Here is a Fokker B.V and Ontwerp 115,also with T.VII.

Ontwerp 147 seems to be very like the postwar F.25

A little bit. F.25 was Ontwerp 217.