Topic: Alcock A1 (Sopwith Mouse) build thread

   It was about a year ago that Pup Cam put a small write up and a three view of a WW1 Scout plane, nicknamed the Sopwith Mouse, also known as the Alcock A1 on the forum.  After months of further searching and asking around no more information was found , therefore what Pup Cam had is what I am working from .  During WW1 Flight Lieutenant John Alcock assembled this curious one off fighter plane at Moudros.  Alcock took the forward fuselage and lower wings of a Sopwith Triplane, the upper wings of a Sopwith Pup and the tailplane and elevators of a Sopwith Camel, and married them to a rear fuselage and vertical tail surface of original design.  Alcock never flew it himself, but squadron-mate FSL Norman Starbuck made a few flights in it, the first on 15 October 1917. However, it crashed in early 1918, was written off and never flew again.   My plan is to build a 1/3 scale model of this over the next few months and have it flying next year.  I will be using Mike Booth’s plan of the Triplane for the front of the fuselage and lower wing, and Mick Reeves wing plan of the Pup and the tail plan of the Camel.  So as with the real aircraft I intend to marry the bits together and make up the rest as I go along , with some guidance from Mr Bones .  This may take some time as I am in the middle of moving the workshop (garage and workbench) from one location to another, so please have patience with my build.   Any tips and guidence would be welcome as well.

Aye up 

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Well the build has started with the chopping up of a few bits of wood and a bit of glue (Pup Cam this is all your fault).  The main dimension was taken from CeeJay’s nicely spun cowel, this was used to produce the front former and the rest was worked back from there.  I have only managed a few hours work but the basis of the fuselage is coming along, I have had the wing ribs cut for the lower wing and an having the top ones cut, this will make the build quicker and easier and more accurate, but the rest will be scratch built. Here are the first few piccy’s

By the way, I need a good Zenoah 38 and reduction drive them things ain't cheep you know

Aye up  

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Wot 'e said!

(Pup Cam this is all your fault). 

Looking forward to this Paul

Alan

And now the first set of questions .......

1) What wood are you using for the longerons?

2) How have you joined the rear longerons to the front section?

3) How have you shaped the rear longerons?

Or is the answer to 2) & 3) scarf joints onto stubs - can't quite see

Alan

The wood that is being used for the build is cyparis both in the longerons and the wing spars.
The front and rear are joined by two 1/4 ply frame sections doweled and bolted for ease of transport.
And finally the rearlongerons were steamed and then clamped over a former until they cooled and set, this was easier than saw cuts and glue and stronger.  I will show some photo's of the two halves tomorrow.

The wood that is being used for the build is cyparis both in the longerons and the wing spars.

   

And finally the rear longerons were steamed and then clamped over a former until they cooled and set, this was easier than saw cuts and glue and stronger. 

Excellent I will give that a go - been wondering how best to do that.  It appears that Cyparis steams well!   How long did you leave it to set? 

Alan

It appears that Cyparis steams well!   How long did you leave it to set? 

They were steamed for about 30 mins, but they only took about 5 mins to cool.  I used a piece of guttering down pipe wrapped in some rags small hole at one end as a vent and for the steam I used a wallpaper steamer.  I didn't put the whole piece in just the area that required bending.

A visit to a friend Phil Noel yesterday to go through the drawings of the top wing ribs was very interesting, he has digitized them for me and will get them cut, saving many hours, it is reallygood watching someone who is very good with CAD.  I manged to get a few hours building in today after tidying the garage to make a little more space to build in. First job was to cut the formers for the top of the rear of the fuselage and then add the stringers. Then to the sides of the front of the fus, these had to be measured and then cut as there are no patterns for these parts.

This photo is of one of the joining formers between the front and rear fus halves, this is then followed by the rest of todays building.

Looking great Patriot, this is going to be a very pretty aeroplane me thinks

At the fuselage joint, there is obviously more structure to go in, but what? Also, are you fitting diagonals to the rear end or cable bracing, or neither?

Looking at the scale drawing, the Pup wing was modified as the aileron is now much bigger, any clues what goes on with the lower Triplane wing

Just arsking

Ian.

Ian
There is more to go into the joint there will be bracing at the corners and there will also be diagonal bracing at the rear end and will be of balsa as it will not be seen.  The ailerons will be to the inner struts, I have had the ribs cut and will be starting them over the next few weeks.  The bottom wing has no ailerons so is very straight forward.  Hope that answers a few of you questions.

Just building the tail at the moment and should have a few pictures to add tonight.

Paul

I have managed a bit of build time this weekend and have cut the ribs and assmbled the tailplane, as this is a mid mounted tailplane I have had to design a way to mount it and make it removable to fit in the car.  I took the basic design from Mike Reeves Camel and broke it down into three sections.  The centre section slots into the rear of the fuselage, I made a platform for it to be screwed to and set that on the centre line of the fuse with zero degrees incident. With the centre section screwed in place the outer panels could then be plugged into place, a tape was then used to check that the assembly was straight and central.  Plans for this week are to get the diagonals into place and make a servo tray to take the two elevator and one rudder servos.

At some point I will need to set the wings in place, so would someone be able to explain how to set up the incidence for under-cambered wings please.

Here are a few photos of this weekend’s progression.

Very nice Paul, beginning to really look like an aeroplane now.    

I like the look of the dowel tailplane leading and trailing edges.   What car has it got to fit in and what's the plan for holding the tailplane panels on? - Just the bracing wires or hidden screws & captive nuts or ......

Incidence is set relative to the chord of an aerofoil i.e. the line that joins the leading edge to the trailing edge, see here.     It will be clear that in the case of a flat bottom section if the flat bottom is horizontal the aerofoil will automatically be at a +ve angle of incidence as the chord line position is higher at the leading edge than the trailing edge.  

So, one way to set the incidence correctly would be as follows:

Calculate the appropriate offset or difference in height of the leading edge to the trailing edge

 

Sorry about the rubbish wing section sketch - it shows the PupCam Superior, a particularly inefficient wing section

Assume for this example the chord = 200 mm and required Angle of Incidence = 2 degrees

Using simple trig

Difference = Chord x Sine( 2 degrees )
               = 200 x 0,0349
               = 7.0 mm approx

Mark the chord on a free wing rib and position this on the fuselage side in order to set the appropriate distance from your zero degree datum for both the leading and trailing edges.  

In the sketch I've cheated and said that the lower longeron is at 0 degrees and so used it as the reference but it doesn't matter.   In the case of the Sopwith Triplane the upper longeron appears to be at 0 degrees (although I can't see any explicit statement that this is so on the drawings that I have).  So in my example, if it where a Triplane, the leading edge would need to be set 7mm higher than the trailing edge with respect to and at right angles to the upper longeron using the marked up rib.  

As to the correct angle of incidence for your section I will let others offer advice but I assume it is likely to be around a couple of degrees +ve i.e. very similar to the Triplane.

HTH

Alan

Thanks for the info.  The model has to fit into a Vectra.  The tail sections are connected with a tongue and tab arrangement with a T nut and bolt, see the photo.

Paul

Just measured the angle of incidence of the lower wing on my Triplane drawing and it came out at 1.99 degrees (bad practice though should never measure off drawings).   Also checked in the small "Air Board Technical Notes"  book that contains the rigging notes for the "Sopwith Biplane F1" i.e. the Camel and it states that upper and lower main plane incidence is 2 degrees.

Looks like 2 degrees would be a pretty good place to start.

By the way, the "Air Board Technical Notes" book is £1-65 and a fantastic little reference.

Alan

Thanks Alan, book has been ordered.  2 degrees it is then, should be fun setting it up.  Need to contact Solutions next week and order the spars for the wings, going to Newcastle beginning of December so will be able to collect from him.  Need to get the wood for the strutts and the undercarriage as well, not to sure what to use though, we'll see.

Well it's been a month since I last posted, not much done, but slowly getting there, loads to do else where and a visit to the North East to collect some goodies from Fighter Aces and Solution, can now get on with a bit more.  Got a bit done, seat made, more to the tail done, undercarriage made and a little more to the front done. The struts that run through the fuse have be made but not finished.  The airframe should be ready for covering in January. Just a couple more photos of the progress.

Well was going to make a start on the lower wing tonight and found that the spars are just a little bigger than the hole, think this is due to the dampness in the garage, bit mifted coz I now need to find someone to resize them for me, so not much to do now until this problem is sorted.

eek a mouse get the cats

Come on then Paul, let's see the piccies

Alan

Will sort some this week, have been busy but will try and take some more

We're waiting  Paul     

We're waiting  Paul     

We soitenly are

Ian.

are we there yet..... 

Right the build so far, the top wings are complete, well almost (required to finish, the servo mounts and closed loop, and the strut mounts) and then covering, the bottom wings need the mounts for the struts completing but this can only be done once the wings are mounted and the final positions set for the struts.  The rear of the fuselage just requires covering, this has been rigged and servos mounted and closed loop control done.  The front of the fuselage is where the most work is required, from the front, the throttle servo and linkage needs to be done, followed by the battery and fuel tank mounts then the cockpit details need to be sorted, (please CEEJAY), the undercarriage is almost complete, just need to assemble the wheels and make the mounting brackets.  Final jobs will be to cover, balance, test fly and then paint and final finishing bits, will down load some pictures soon.

Wing assembly.
The top wing was standard simple assemble, the ribs I had laser cut for consistency, these were glued onto the spars, with ply ribs being place at the strut mounts and at the joiner points, each rib was capped with 1/16 balsa and the leading edge was 6mm dowel with a lite ply trailing edge and the curved tips were made out of laminated 1/16 ply wrapped around the 1/8 balsa sheet.  The ailerons were assemble in much the same way as the wings, balsa leading edge and a lite ply trailing edge.

The bottom wing was assembled slightly differently with the ribs being slid onto the spar, with ply ribs in the main support areas, the leading edge was ¼ square on it’s edge and shaped to fit but the trailing edge was lite ply again with the tips being formed the same way as the top wing.  The other difference is that the bottom wing has no ailerons.

Rudder and Elevators assembly.
These were made of strips of 1/16 ply 6mm wide, the elevators were formed around a ½” balsa former and once dry it was removed and the ribs were added. The rudder was built on a flat board on a drawing and again once dry the ribs were added. The strength was increased with a bit of cross bracing.  Then the rigging was added to stiffen the back end up.  The holes for the 1/8-inch Robbe hinges were drilled using a Robbe hinge jig.

The control horns for the closed loop were made out of 2mm fibre glass sheet and cut by hand, cutting these I thought was going to be simple, but after 2 or 3 blades in the scroll saw I decided a different approach was required, so a junior hacksaw blade was modified and fitted in the scroll saw and all was well, mind you the little ones get the fingers a bit close to the saw blade,

The servos for the elevators and the rudder are mounted in a simple box mounted in the rear half of the fuselage, the receiver will also be mounted here.  Loads of small bits were purchased for the closed loop and tail rigging, but once fitted I realised that I had not got enough and the shop have now run out so another week before the rest of the bits come in, but here are the bits done so far.

And finally for today I wanted to see it assemble so here is a quick pic so far.
43

Cor, you 've been a busy boy, nice work   

That looks really good Paul, it's really coming on.   You've made excellent progress (unlike someone else I could mention )

Those lower wings loook familiar!   I like the R/C module idea, keeps it simple and easy to get at.

Looking forward to seeing it in the wood.

Alan

Coming on great matey, certainly will be a refreshing change to the 'dullards choice' of Sopwith, namely the Pup and the Triplane, its nearly as refreshing as a Camel or five

A better pic of it assembled would be nice though

Ian.

Nice tidy work there mate.
Bonzey

Nice tidy work there mate.
Bonzey

Bonzey, now you have that WWII crate out of the way, you can get back on the SE5a huh? Whats the current state of play with that, I have seen some hints in the background of the Tiffie pics

Ian.

Hi Ian (hijack time ), The Se5 will be back on the bench again vary soon. The fuse half of things is about done and covered, with the Z38 and gear fitted now instead of the 3W 75 that was in it the last time you see it.
I have started drawing the wings and these should be an easy build. I'm hopefull to have it at least looking like an Se5 for Roughham.
Bonzey

Good to hear Ken.

Paul, great job so far, looking forward to seeing it in the wood

Steve

I would like to bring it to Rougham no matter how far the build is just for static if allowed