Sopwith Snipe Project

[Jeff Brooks]

thanks John,
but that, like the others I found, comes with the cable attached. I need just the adjuster. I have some 75' of b owden cable with no way to attach it to the throttle.

[Nick]

Originally Posted by Jeff Brooks

NIck,
Where did you find the cable adjuster for the triggers? I have been looking for these, so I could complete the throttle quadrants Vet made. I am waiting for the AN bolts from AC Spruce, and the cable adjusters and I am done with them.

Jeff,
I got them from a Motorcycle wreckers but you can buy them new from motorcycle shops without the cables. They'll sell a cable repair kit as well for making up cables of any length.

Cheers, Nick

[Nick]

Just out of interest this is a photo I took at the Imperial War Museum in London last year of the set up for the Constantinesco CC Fire control timing gear which amongst other aircraft is also used on the Snipe.



This picture of the Snipe shows the reservoir mounted on the outside of the fuselage vertical struts and a slide arrangement on the inside to presumably pump up the pressure.



Here’s a weblink regarding George Constantinesco and his invention but to be honest I still have no idea how this thing worked or would be operated.

Firing between the Props

Can anyone explain basically what these components are? I’m guessing the parts at the top of the Museum picture are the trigger motors mounted on top of the guns. Then maybe the other gizmos are the generators which measure the RPM. Where would these have been mounted on the engine? It mentions that before starting the pilot would ensure there was no air in the system by opening an air release valve while the Bowden control was pressed. Where would the air release valve be? Possibly on the side of the reservoir?


Cheers, Nick

[FlyXwire]

Hi Nick,

Here's a few diagrams that'll help you in the C.C. gear's operation.

General function schematic:



Function schematic (detail Type A):



Function schematic (detail Type C):

[Nick]

Originally Posted by FlyXwire

Hi Nick,

Here's a few diagrams that'll help you in the C.C. gear's operation.

Hi Dave,
That's fantastic, many thanks for those, much appreciated, that gives a much clearer picture of how it all interacts.

Cheers, Nick

[gbwez]

What a great thread this is, Nick your work is inspirational. Several pages back you were looking for help with shaping the complicated Sopwith leading edge. The thread linked below follows the progress of someone making a set for a Pup (looks like the same as the Snipe).

Sopwith Corner

[Nick]

Originally Posted by gbwez

What a great thread this is, Nick your work is inspirational. Several pages back you were looking for help with shaping the complicated Sopwith leading edge. The thread linked below follows the progress of someone making a set for a Pup (looks like the same as the Snipe).

Sopwith Corner

Thanks Gbwez,
That's an interesting thread that I hadn't found before.
Great looking nosing that he made. I haven't done mine yet, but would be happy if it came out anywhere near as good as that. Thanks again.

Cheers, Nick

[drrivah]

Hi Nick:
Not to be off thread, but could you say a few words on the original Snipe
electric/ignition system and what your plans are for your build. Which mags will you use, and will you go with an alternator? What about battery?

Thanks.

-pete

[Nick]

Originally Posted by drrivah

Hi Nick:
Not to be off thread, but could you say a few words on the original Snipe
electric/ignition system and what your plans are for your build. Which mags will you use, and will you go with an alternator? What about battery?

Thanks.

-pete

Hi Pete,

Originally it didn’t have a generator, except the later night fighters had a wind driven generator. The battery on the standard Snipe was just for the cockpit lighting and would have had to be regularly recharged and replaced.
I don’t have a Bentley BR2 engine unfortunately and will be using a W670 radial with Bendix Magnetos which I’ll wire up to the old Air Ministry switches.
As for a Generator I haven’t decided yet as it’s all pretty heavy stuff so a lot will depend on how it all weighs in, and the space. I’m currently thinking along the lines of not having one. Only need a battery for starting if I put the starter motor on it. A while before I have to work that one out but may well end up using an external battery for starting or just be one of the many aeroplanes here that need hand swinging.

Cheers, Nick

[j ferguson]

The gun firing system shown in the drawings so kindly shared with us appears to work as follows.

1. It is a hydraulic system. Two 'bumps' on the pulse generator cam push a piston. The resulting pulses are timed to fire the gun when the propeller blades are out of the way.

2. The parts identified as "reservoir" include a bypass valve which vents the pulse pressures back into the low pressure side of the reservoir except when the trigger is pulled (pushed). The pulse power when bypassed - trigger not pulled - is not enough to fire guns.

It looks as though the "needle valve" not only closes off the bypass when the trigger is pulled but may also push the ball valve open. Alternatively, the ball valve may act as a pressure relief valve which vents excess pressure into the "high pressure" side of the reservoir. this would make sense if there is no other way to relieve excess pressure on the gun side of the system.

3. the second drawing shows "bleeder" wing nuts on the gun "motors" it also shows a filler opening (#37)where hydraulic fluid can be added. The "Bleeders" #23 on the second drawing are where the air in the system is let out.

4. there is a spring-loaded (spring in tension - pulls down) plunger in the reservoir. It looks as though the hydraulic fluid is topped off through port #37, the bleeders on each gun "motor" are opened,(#23), the plunger is pulled back and released and the bleeder wing nuts are tightened when bubble-free fluid comes out. (this is just like bleeding the brakes on a car. The "motors" are just like the hydraulic cylinders in your car, more apparent in drum-brake setups.

I suspect that the first drawing has been oversimplified because it shows the plunger rod fixed to the piston. It seems more likely that it would be a sliding connection so that the handle wouldn't stick out when the high-pressure cylinder was full. Or if it is a fixed connection, maybe the "motors" were bled until the handle went down.

'Seems to me that this is one more example of a really slick design to solve what must have seemed a very complex problem before it was solved.