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Question Danish Fokker D.XXI Madsen Cannon


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I'm currently building a Matchbox Fokker D.XXI to be finished as a Danish version with a pair of 20 mm Madsen cannons.
As seen in this photo, the barrel of the left cannon is not in the center of the gondola, but offset to the left (outward), I didn't find any photo of the right gondola. My question is that the right cannon is offset to the right (outward) or to the left (Inward).

0000284.jpg

Any help will be appreciated.

Jun in Tokyo
https://www.flickr.com/photos/horaburo/albums

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3 hours ago, Junchan said:

I'm currently building a Matchbox Fokker D.XXI to be finished as a Danish version with a pair of 20 mm Madsen cannons.
As seen in this photo, the barrel of the left cannon is not in the center of the gondola, but offset to the left (outward), I didn't find any photo of the right gondola. My question is that the right cannon is offset to the right (outward) or to the left (Inward).

0000284.jpg

Any help will be appreciated.

Jun in Tokyo
https://www.flickr.com/photos/horaburo/albums

Aircraft guns do not just face forward, they are "harmonised" to the gunsight.  The guns are angled inwards to a predetermined imaginary point in front of the aircraft  at which point the pipper of the gunsight is set to converge where they meet.  this concentrates the gunfire at one point to do maximum damage. The difficult part for the pilot was always getting the correct distance from the target so fire was concentrated on it, which up to ww2 was done by estimation, the other point was being able to "lead" the target, firing in front of a moving aircraft so it ran into your gunfire. The purpose of the ring on ring and bead sights was to aid the pilot to do this.

 

Selwyn

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I think the OP is referring to the fact that the barrel doesn’t emerge from the centre of the pod, rather than the fact it’s angled inward.

 

J.

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I'm not sure that I'd agree with it not being centrally aligned, from that photo.  The red line does not appear to pass through the bottom dead centre of the gondola nor halfway between the fairing over the wing. However, the design of the gondola will depend upon the entire shape of the gun: barrel, breech and feed mechanism.  if the shape requires offset packaging then the gondola will be asymmetric and the barrel will appear offset.  The leading edge sweep of the D.21 does not (from memory) to require any significant asymmetry in the fairing, but perhaps this should not be ignored.

 

The barrel angling does seem a little excessive for bore-sighting reasons.  Would things appear different if the photo had been taken from directly in front of the gondola aircraft rather than from the left (photographer's left) of the gondola?  Wouldn't it be nice to have lots and lots of photos?  If only.

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I think it's a perspective problem and Graham is right - gun is in centre of pod. Note how the wheel strut cover in the photo looks bent - I'm fairly sure they were straight.

Searching "Danish Fokker D21" brings up a few pictures.

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Looking at the background of the photo everything looks slightly distorted. The photo could have been copied many times and become distorted.

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9 minutes ago, dogsbody said:

I didn't know Matchbox did a D.XXI! When did that come out?

 

 

 

 

Chris

That's the PM kit reboxed, something like '93.

I managed to locate the Phalanx booklet on the type. Mr Eberspacher draws the barrell dead centre (p. 17). The only pic of a Danish a/c with gondola only shows a 7/8 side view.

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3 minutes ago, Vesa Jussila said:

Matchbox is reboxed Pioneer kit. I think it was in market only short time.

 

1 minute ago, tempestfan said:

That's the PM kit reboxed, something like '93.

I managed to locate the Phalanx booklet on the type. Mr Eberspacher draws the barrell dead centre (p. 17). The only pic of a Danish a/c with gondola only shows a 7/8 side view.

 

 

Ah! I remember that. I have an old Pioneer kit and another D.XXI from SIGA models. They are different molds but very close to each other. Then, the old FROG kit was about the same.

 

 

 

Chris

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Just to clarify, the only Danish Fokker to carry cannon pods appears to have been an experiment with J-42.  One pod carried a 20 mm cannon, one a 23 mm cannon.  The 20 was found the best but none were mounted in April 1940, and were only on J-42 when it was in overall silver.

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Many thanks for your inputs guys. 

As Chris said, the Matchbox kit is a rebox of the Pioneer2/PM kit.

0000284_3.jpg

 

I have the Phalanx monography as well as the Lela Presse monography by Peter de Jong from which I posted the head on view of the cannon pod, but a 3-view drawing in this book shows the barrels in the center of the pods.

I've never heard of J-42 has installed with a 20 mm and 23 mm on each wing. Both of the above mentioned 2 book describe that the Danish D.XXI carried a pair of 20 mm cannons.

 

Jun in Tokyo

https://www.flickr.com/photos/horaburo/albums

Edited by Junchan
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OP is right in assuming the barrel wasn't centered in the pod - it wasn't. I have clear pictures showing that. However, I was unable to find a clear view of the starboard side pod, but judging from one picture it could look like is was a mirror image of the port side.

 

Jens

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9 hours ago, Junchan said:

I've never heard of J-42 has installed with a 20 mm and 23 mm on each wing. Both of the above mentioned 2 book describe that the Danish D.XXI carried a pair of 20 mm cannons.

It was news to me also; I remembered that only J-42 had the cannon pods but my research for the Classic Airframes kit was quite a while ago, so I wanted to make sure, and found this in the midst of a discussion of Danish proposed fighter projects:

 

from https://www.secretprojects.co.uk/threads/indigenous-danish-fighter.5357

Oct. 4, 2020 from 'Orla'

 

D.XXI J-42 did not have two 23mm. Madsen macnine guns under its wings when testing, but one 20mm. and one 23mm. cannon as the Hærens Flyvertropper wanted to test the reliability, functionality and service ability for each veapon. In the end, the 20mm. canon proved much more reliable than the 23mm. and thus was chosen for the task. For some reason, political I guess, the ordered 24 pcs. of 20mm. Madsen machine guns and ammunitions was never delivered from the factory.

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I can't help feeling that two 20mm (or 23mm) external cannon would be a bit heavy/cumbersome for a D.XXI.   Who made the 20mm cannon, Oerlikon?  That would certainly be lighter and better than (say) two Hispano.  Less effective, but you can't have everything.

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3 minutes ago, Graham Boak said:

I can't help feeling that two 20mm (or 23mm) external cannon would be a bit heavy/cumbersome for a D.XXI.   Who made the 20mm cannon, Oerlikon?  That would certainly be lighter and better than (say) two Hispano.  Less effective, but you can't have everything.

The cannon would have been a Madsen, a wellknown Danish company.  I seem to recall that Lockheed tested the 23 mm on the P-38 Lightning.

 

/Finn

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1 hour ago, Vesa Jussila said:

20mm gun was tested in in Finland too. If I remember correctly tested gun in Finland was Oerlikon.

 

 

 

Yes, Finns tested the Oelikon FF and Danes used the Madsen 20 mm cannons.

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Jun in Tokyo

https://www.flickr.com/photos/horaburo/albums

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