Spitfire Canopy Rails for Static

The curvature of the rails that people see is due to the rivetting process that stretches the metal slightly along its length..Mick Subritski here in Australia has some canopy rail in stock last I heard.

Hi Spitfire Cockpit builders.

I have an original 300 part which is the ‘end stop’ fitted into the end of the  the canopy rail  near fr12.

Part number is 30027 151.

It is useful as it shows the internal dimension of the canopy rail.

Its dimensions are in mm

22 . 37 x 9 . 2.  The bit that extends into the runner gap is 9.05mm wide. The extension is on the C/L. The bit that extends into the gap is 2.77mm high which would be just under 12 swg which indicates the wall thickness’s of the rail.

I believe the outside dimensions from other original items are 1″ x 5/8 “.

Of course this varies a bit because the rail is made of 3 parts.  Top hat and 2 side rails.

Incidentally I have found an extrusion that is very close to this and looks and works spot on with out any machine work.

Any one interested is welcome to ask for more info.

regards

Jon.R

Sweet work,just like supermarine would have done it with the prototype..Make it fit!!!!

I have made “dummy” Spitfire Canopy Rails ie without any cut outs to allow the canopy to slide in the runners. I used 1″ x 1/2″ wood with 10mm x 15mm of 1mm angle aluminium as the flanges. This has enabled me to check the canopy fitting and the general alignment of the fuselage to ensure that the dimensions all agree with those provided in this thread. More by luck than by my accurate woodwork all seems to be OK so far.
Clearly these will not be adequate to provide an operational canopy but its a good start.

Here are a couple of photos (poor quality) and a couple of drgs, showing the canopy rail, and arrangement thereof; the 2nd drg is a section at the front of the canopy assy, and ironically it shows the packer as being thinner there than the section (drg1)further aft.

Just for my edification then, the kidney bean sliders bear against the doubler of the canopy rail (through which the rail is rivetted to the skin) and the closed part of the rail forward of F11.

The rail is parallel with the skin at all times, and the outer profile of the fuselage changes shape, becoming progressively narrower the further rearward it goes, but the knuckle line remains a constant dimension despite the drg showing there to be only .15″ tolerance between the inside of the canopy frame , and the outside of the rail.

Yes Stuart the knuckle line remains constant dimention of 11″ either side of the centre line. See drg’s no’s I put on earlier posting.

Steve

So there is 2 tenths difference over a run of about 40″?

I was talking port side from the door aperture rearward. Dimensions approx.

I had a little ‘inter-granular’ in one of the tapered strips and some retained distortion caused when the canopy was wrenched off in flight…and terminated testing at Boscombe Down!

Mark

So there is 2 tenths difference over a run of about 40″?

Speaking purely for the low back fuselage, for which I have first hand knowledge.

The canopy rails/track to the rear of frame 11.

The rail is made of an extruded/or milled ‘top hat’ section.

There are two strips of aluminium rectangular section which are riveted to the upper and lower flanges of the ‘top hat’ section to contain the slider but allow the slider studs to run clear and engage the canopy fixings.

This is the clever bit. Those rectangular strip sections are tapered in thickness, getting thinner toward the rear, from memory tapering down from about .3″ to about .1″. This to allow for the two tracks to remain parallel, in plan view, to each other but the fuselage to taper in toward the tail.

Mark

Just for my edification then, the kidney bean sliders bear against the doubler of the canopy rail (through which the rail is rivetted to the skin) and the closed part of the rail forward of F11.

The rail is parallel with the skin at all times, and the outer profile of the fuselage changes shape, becoming progressively narrower the further rearward it goes, but the knuckle line remains a constant dimension despite the drg showing there to be only .15″ tolerance between the inside of the canopy frame , and the outside of the rail.

…to shut it?

Mark

Hi Mart 12, Yes to shut it !!! If you look at the diamentions you will see they are taken from the horizontal datum, the largest 15.38 being fwd & the smallest 14.91 being aft.
I know its only a small run, 0.47″, but up hill it goes .

Steve.

Cheers Steve (and others) for the excellent advice. It will not fly….unless the fus hits a particularly large pot hole on the motorway…..will send pm

The knuckle line is 15.38″ above the datum at the front of the cockpit door. At FR11 it’s 15.12 above the datum & at FR12 its 14.91 above the datum, ref drg 37927-73. So there is an up hill run on the canopy rails.
Hope this ends the confusion.

Steve.

…to shut it?

Mark

As part of project managing my static Spit fus project, I now need to source some suitable canopy rails….if anyone has any leads or knows where I can get some made please let me know. These are the rails that the canopy ‘beans’ slide in and is therefore fitted to the airframe.
Obviously static originals would be best but I will take anything as I really need to ensure that when the project requires them, we are ready to go…..

for your info this fuselage will be part of a display ‘Spitfire Experience’ which will seek to show the public what the Spitfire actually means, what made it the legend etc. There will be the Spit fuz, a Merlin and lots of ‘people’ memorabilia (Spit Fund, trench art etc). I am hoping it will do a bit of travelling to non- and aviation events. The website shows embryo pictures at the moment.

Hi Rocketeer, if you pm me your address i could send you a portion of canopy rail so you could make your own. I think with some wood and a router you could produce the very thing you need, assuming your not going to fly it !!!!

Steve.

In very broard terms, the canopy rail narrows 1/2″ from F11 to the fully open position; as previously stated, at the front fully closed, the width is 23″ approx and at F11, (fully open it) is 22″; some of this change in shape is taken up by the actual sliders which attach to the canopy by pins that are free floating themselves.

I would think problems opening the canopies in service would be a combination of poor alignment of the door, the floating pins not moving as they should, and the fact that the main sliding rails (which are fixed) are aluminium, as is the surface they run on; not a good combination.

I am not familiar with the attachment for the mkI (pre Martin Baker) canopy, perhaps Mk12 can shed some light on this.

Hi Rocketeer, its seems that MK12 is the closest to the mark on canopy rails. Here are some measurements for you to work to. The knuckle line of the canopy rails is 11″ either side of the of the centre line of a/c ALL THE WAY ALONG, so no taper!!! See drg30027 sht 34 cockpit combing & 30027 sht 59 cockpit door. Also 37927-73 for FR12.
The knuckle line is 15.38″ above the datum at the front of the cockpit door. At FR11 it’s 15.12 above the datum & at FR12 its 14.91 above the datum, ref drg 37927-73. So there is an up hill run on the canopy rails.
Hope this ends the confusion.

Steve.

The “floating pins” are part of the MB jettison gear, that have removable clips on the ouside of the canopy, that in turn are attached to wires that eventually end up inside the canopy terminating in the “emergency release” ball , which when pulled, removes the clips, and allows the canopy to expand to its actual size, slipping off the pins that hold it to the brass/ bronze sliders, and away into the slipstream; if the tear drop canopy does not do this, how is it jettisoned?

The teardrop canopy does have the same system although the rear slider has a different profile. The release mechanism is behind the broad base of the canopy frame by initial design rather than an adaption as on the high back canopies. Still precious little float on the slider’s studs in to the canopy receptacles which are axially located and fixed, through the cross drilling, by the small dual pins of the release mechanism.

mark

The “floating pins” are part of the MB jettison gear, that have removable clips on the ouside of the canopy, that in turn are attached to wires that eventually end up inside the canopy terminating in the “emergency release” ball , which when pulled, removes the clips, and allows the canopy to expand to its actual size, slipping off the pins that hold it to the brass/ bronze sliders, and away into the slipstream; if the tear drop canopy does not do this, how is it jettisoned?

If one removes an original rail from an aircraft, it can be seen to curve, so the rails do taper to the rear.

There is indeed a general slack fit of the sliders in the rails. The length of the pins does allow a degree of movement of the canopy sides up and down the pins.

Many years ago, Tim Routsis examined a set of original brass blocks and sliders and concluded that they must be very worn, so went and redrew them. A couple of weeks later, with the new parts in hand, they were fitted to the aircraft – and jammed, horribly. A fettling session ensued; by the time they worked correctly, they looked exactly like what we had started with!

Bruce

In very broard terms, the canopy rail narrows 1/2″ from F11 to the fully open position; as previously stated, at the front fully closed, the width is 23″ approx and at F11, (fully open it) is 22″; some of this change in shape is taken up by the actual sliders which attach to the canopy by pins that are free floating themselves.

I would think problems opening the canopies in service would be a combination of poor alignment of the door, the floating pins not moving as they should, and the fact that the main sliding rails (which are fixed) are aluminium, as is the surface they run on; not a good combination.

I am not familiar with the attachment for the mkI (pre Martin Baker) canopy, perhaps Mk12 can shed some light on this.

Still puzzled.

Floating pins? Floating where?

On all my canopies, both high back and low back fuselage, the rails on the fuselage were aluminium section and the canopy sliders where bronze or in some cases possibly brass. The sliders had two steel studs screwed in to them that engaged in to steel receptacles on the canopy frame. The studs and the receptacles were cross drilled to accept the quick release pins. Nothing floating here.

If the the rail-tracks do indeed taper to the rear, and I am still sceptical but will checks at AA today, in my view it must be accommodated by a general slack fit of the sliders in the ‘T’ section rails.

Mark

In very broard terms, the canopy rail narrows 1/2″ from F11 to the fully open position; as previously stated, at the front fully closed, the width is 23″ approx and at F11, (fully open it) is 22″; some of this change in shape is taken up by the actual sliders which attach to the canopy by pins that are free floating themselves.

I would think problems opening the canopies in service would be a combination of poor alignment of the door, the floating pins not moving as they should, and the fact that the main sliding rails (which are fixed) are aluminium, as is the surface they run on; not a good combination.

I am not familiar with the attachment for the mkI (pre Martin Baker) canopy, perhaps Mk12 can shed some light on this.