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JackG

Hythe Gun Camera

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Anyone have any dimensions for this as I have to scratch build one in 72nd scale.  I have a Lewis gun, but would like to know where it needs to be cut, along with:

- camera box dimensions?

- barrel (containing the lens and shutter) diameter and length?

 

datasheet_2411_datasheet_image2.jpg

 

hythe.jpg

 

tpg1.PNG

regards,

Jack

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Björn B, thanks for that link. 

I tried using one of the measurements on the diagram I had posted above, and well, it was way too big when scaling the gun around the camera box.   So have used the overall length of 38.5 inches, scaled at 1/72 ,  giving a measurement of 13.58mm overall.  The orange sections are the camera box dimensions:

 

hGaSKF8.jpg

 

 

 

regards,

Jack

Edited by JackG

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Looking at pictures makes me think that the camera box is to small on the drawing. It looks like the bottom should go lower.

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24 minutes ago, Ivor Ramsden said:

If you can wait a couple of days I can measure the one that we've got on display in the Manx Aviation & Military Museum.

That would be great!

 

regards,

Jack

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Here are the full-size measurements from Hythe camera gun no.1777 of 1917, measured in mm because they are easier to write than inches and fractions:

 

Length overall 975mm

Barrel diameter 82mm

Barrel length to camera box 360mm

Camera box 123mm high,  70mm front to back,  88mm wide.  Centralised on barrel,

Ammunition pan 205mm diameter, 30mm deep.

Ammunition pan centred 330mm from rear end of gun handgrip.

 

I hope this helps.

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Ivor, that is excellent - thanks very much for providing these dimensions.

 

regards,

Jack

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If this is for your Siskin, Jack, note that no "ammunition pan" was fitted, and the gun camera was mounted "upside down" with the trigger grip vertically upwards. The mount was on the top mainplane centreline with the butt about level with the bottom mainplane trailing edge. the gun camera was mounted parallel to the aircraft datum (top longeron) with the butt raised above the mainplane surface by the mounting to achieve this.

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Dave, thanks for confirming the gun camera orientation.  I noticed the upside down placement on one of the Granger drawings of the Siskin III, but wasn't sure after seeing this photo.  I guess it's just light reflection on the hand grip making it look like it was hollow or something else;

 

FbmLUSX.jpg

 

Does look solid like hand grip here:

 

WXBdFt3.jpg

 

------------------------------------------------------------------

 

Any idea what the dark strip down the center line of the wing is, or what it is for?  Extends completely along the bottom as well:

 

k50TmaZ.jpg

 

YxbhHu2.jpg

 

 

regards,

Jack

 

 

 

 

 

 

 

 

 

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1 hour ago, JackG said:

I guess it's just light reflection on the hand grip making it look like it was hollow or something else;

No, that's hollow. the hand grip will be part of the trigger mechanism, the trigger guard and hand grip outline will be a part of a metal frame on which the trigger mechanism is mounted (inside the gun)

1 hour ago, JackG said:

Does look solid like hand grip here:

Yes, this is the same as above but with (most likely) wooden cheek plates either side of the hollow metal hand grip frame. These woould be needed for comfort if the gun was being used as per the photo in post 1, but weren't essential on a solid mounting on top of the wing. Note the butt hand grip is missing as well on above both photo's, the fixings for this being used for the aft over wing mount.

1 hour ago, JackG said:

Any idea what the dark strip down the center line of the wing is, or what it is for?  Extends completely along the bottom as well:

That's a cover strip over the joint for the two upper wing sections. These would be joined on the centreline with bolts through the wing spar ends, whci requires a gap between the inner ends of the main wing structure to access these (large) bolts. The gap is covered by a metal strip attached with small screws. It's common on many aircraft, eg there's one on each wing of a Hurricane where the outer wing panels are bolted on.

 

I'd just been looking for a copy online of this photo of 59, I'd just found it in Air Enthusiat 70/p39 where it is captioned "the 1930 RCAF Siskin Exhibition Flight of F/O E A McNab, F/L V Beamish (leader) and F/O E A McGowan in front of their Siskin IIIa's"

I presume you've spotted the John Alcock inscription below the cockpit, and what I take to be the inscription for Arthur Whitten Brown below the cockpit of the Siskin parked behind (no 2? - alegedly 20 from other posts) plus the hythe camera above the wing. No evidence of any nav lights or mounting brackets for same, or the over wing ID light.  As the underside ID light seems to have been mounted internally flush with the lower fuselage surface, I'd guess there'd be a hole or window there even if the light wasn't fitted. Presume your intention is to finish your model as No 20?

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Yes, no.20 is the plan for the Matchbox kit,  and you have already discovered the thread I had created about the inscription for Arthur Brown.

 

regards,

Jack

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The hand grip consists of a wooden block fixed into a metal frame. In the first picture the wooden block is missing, leaving the skeletal outline of the frame.

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Been thinking over the explanation about the top wing being two pieces gives me an idea for a fix.  Testing the fit of the wing struts, I find the outer ones are too long, such that the center wing doesn't make contact with the cabane struts..  Cutting the upper wing wing in half and then re-attaching them back together with some brass pins gives them some pliability to increase dihedral to give a better fit, but then again maybe it's the bottom ones throwing things off...

 

regards,

Jack

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For a IIIa the upper wing dihedral should be 1 degree, and 3.5 degrees on the outer parts of the lower wing.

The III had both wings at 3.5 degrees.

Just had a look at one of my matchbox kits, the lower wing is about right but the top wing is virtually flat, so for your IIIa a small increase in dihedral wouldn't go amiss. I'd be tempted to try scoring the top centreline and bending the wing first before cutting it in two, you might get the desired effect without the hassle of pinning and glueing it, if it doesn't work you can still revert to your plan.

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Yes, when I lay the upper wing flat on a table there is dihedral present.  In fact, head on profile with both wings in position, it appears to match line drawings.  Looks like I will have to shorten the outer struts.  Must be my cockup, as I haven't come across any build reports having a problem in this area.

 

regards,

Jack

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Some further measuring compared to the Granger drawings.  I could move the strut location holes in the upper wing.  They need to be closer together in the cabane area, by about 3.5mm total.  That would change the angle of the cabane struts, causing them to sit a bit 'taller', thus increasing the height between the wings.  Oddly, there are a pair of ejection pin marks between the rear set of holes, and these look to mark perfectly where the new holes will go.

 

The outer struts could also use a re-alignment of about just 1mm further outward, but will try just the center correction first.  Another check, shows same 1mm outward adjustment on the location hole on bottom wings - so at least the angle of outer struts remains constant.

 

regards,

Jack

Edited by JackG

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Definitely move the top end of the cabane struts inboard to match the Granger drawings. The outboard struts don't look too far out to me, I'd be tempted to see how close the fit is after adjusting the cabanes before moving these.

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Well  this turned into a rabbit hole with a dead end, resulting in  the opposite effect - now the outer struts  fall short.  Gone back to the original holes, and seems to fit better, but now the forward cabane struts are a tad long.   Must have lost the proper alignment in the cabane area,  creating all these fit issues.

 

regards,

Jack

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