Sopwith Camel by Mike Dowling - FINISHED - Model Airways - 1/16

[Mike Dowling]

Are you going to sell it to me when finished ?

[cog]

Nah ... a gift would be more appropriate. Maybe just postage. It's a hobby, what's a bit of distraction time and wood between modeller mates

[Mike Dowling]

Wow, what a guy !! I await your efforts with keen anticipation !!

[cog]

Found me a drawing, can you tell me if it is close enough ...

 

 

What I've seen for Sopwith Camle planes, this would be a fitting prop ... well, actually half a prop

 

sizes based on your given length

total lengt 17cm

max width 1.4cm (I can bring it down to your 1cm)

max thickness 0.94cm seven layers : each layer 0.13xxcm

 

I'll have to order some wood, as the stock I've got left doesn't meet the requirements

[Mike Dowling]

I think that looks great Carl, I think the thickness is fairly critical but less than 1cm rather than more. Max width 1.1cm. Good luck !

[Mike Dowling]

Side bracing complete. I have decided to leave the under fuselage bracing until after I have done the control wires, I think it will give me more space.

 

I have also attached the tailplane and hope to rig it later today. I kep't  knocking the tail skid off so I have sneakily attached a wire to the pin it rotates on which I hope will keep it in place.

 

A question for you John. The instructions say you have to brace the control stick to do the wires. How on earth did you do that ?

 

 

[cog]

Thanks, when I get my wood I'll let you know.

 

She starts to look awefully good Mike

Edited November 18, 2017 by cog

[Mike Dowling]

Another question John - did you find that CA glue fixed the control line thread easily ?

[jablackwell]

Hi Mike,

 

That would work, yes, but there is some concern that CA will make the line brittle with age and cause breaks later in the model's life. Quite a few people here on MSW use a thinned PVA glue instead, and a toothpick or tiny brush to apply to each knot. 

 

~john

 

[Mike Dowling]

John, I have done the same with PVA but I expect you found as well that fast grab is needed in places. As the thread is nylon (I think) it may be OK. I know cotton thread becomes very brittle.

 

Can you give any help on 'bracing' the control stick and, when you did the elevators did you start at the stick as per instructions or did you start at the back ?

[jablackwell]

Hi Mike,

 

I started in the front for all of the control wire rigging. Getting the elevator and ailerons fixed in a level position was easy with some spare sewing thread to tie them in place. The control stick I secured using a jig made out of spare single-strand copper wire... a little flimsier than a paper clip. I then sat the plane on its nose on a block of 2x4 into which I had drilled a hole and placed a rod that fit into the engine mounting hole at the front of the plane. I didn't want the thing to fall over while rigging, and that nearly happened a couple of times anyway! In the instructions note the way they cable over/under the little protrusions on the control stick. This just will not stay put no matter how much you try. You could, I suppose drill fat holes there and thread the cables through them, but I didn't go through this level of care. It will depend on how much you actually intend to move the controls once the model is complete. Mine is for display only, so .... each to their own ;-)  

 

~john

 

 

 

 

[Mike Dowling]

Thanks John, that is a great help especially regarding this silly idea of standing the fuselage on it's nose - it's just so unstable. I didn't think of using the engine mounting hole - brilliant!

 

Don't quite understand about the protrusions on the stick. Do you mean the bits they call pulleys?

 

As for how far I go with this thing I'm not sure. I have done the control leads for the rudder but don't know if they work yet - waiting for them to dry ! If they do then I will keep trying with more but as you say - who on earth is going to play with the controls once done ? !

[jablackwell]

They call them Pulleys, yes.... but they are more like nubs or extrusions, or something.... 

[Mike Dowling]

OK John, I know which bits you mean.

 

Now, questions for anyone !! I have no idea how to fly a plane because I don't know how the controls work but, I can work a rudder out without trouble. It attaches to a foot operated bar which turns the rudder (and in this case the tail skid) left and right depending on which foot you press. Nice simple mechanics.

 

How the control stick works seems to be a whole different ball game. Why should the tail aileron be attached to the stick and the rudder bar ? I know when you push it forward and back the aileron should go up and down but why connect it to the rudder pedal.

 

Presumably when wings are attached the stick works the wing ailerons up and down as well but then what is the side to side motion for ?

 

All contributions to my dense brain are welcome !!

[Landrotten Highlander]

Not entirely correct, but sufficient for purpose of explanation.

Asume for a moment that an airplane can rotate along three axis that converge to a single point located where the pilot sits.  Let's call X-axis the one running along the centerline in a fore-aft direction, the Y-axis running perpendicular in the horizontal plane and the Z-asix runs perpendicular in the vertical plane.

 

In order to rotate a plane along the X-axis, the pilot operates the ailerons by moving the stick sideways.  If turning left, the stick is moved left which in turns moves the ailerons in different directions: the right hand aileron will go DOWN (to increase the lift on the tip of the right hand wing) while the left hand aileron goes UP (to decrease lift on that wingtip).  The resulting forces around the centre of gravity(the point connecting the three axis of rotation) will mean that the aircraft will rotate to the left.  The speed of rotation is directly proportional to the size of the stick movement.

 

Similarly, rotating along the Y- axis means the stick is pulled back/forward which in turn moves the horizontal stabilizer (the flat part of the tail structure) up/down.

Rotating along the Z axis is done by pushing the rudder pedals left/right as eplained in your post.

 

Now it gets a bit more complicated:  Each action of ailerons and rudder produces a secondary effect (a side effect if you will).  When using the rudders each wing tip of the main wing is now subject to different airspeeds, resulting in different amounts of lift.  This causes the plane to start rotating along the X axis as well as the pimary goal: rotating along the Z-axis. Similar but reversed for the ailerons because of a very subtle change in airflow around the rudder.

 

Now, it is much easier to control the heading (direction of flight) using the ailerons than it is using the rudder.  Thus a pilot will change his heading by moving the rudder left/right, and gently counteracting the secondary effect with his rudder.

 

On other thing where the rudder is vitally important is when increasing/decreasing power of the engine.  On a single propellor driven aircraft the rudder is turning in a single direction.  This introduces a torque along the  X-axis making the aircraft turn away from its course along the Z-axis (this is called precession, and is used to great benifit in systems such as navigational instruments but also in steadying guns on a modern warship).  So a pilot taking off will need to press a particular ruder pedal harder (depending on which direction your propellor turns - this should not make a difference when modelling the plane except when telling the story as in a diorama) in order to keep a straight flight path (as in along the length of the runway).

 

Hope this helps.

Slainte

L.H.

[Mike Dowling]

Slainte, although rather complicated I understand - thank you. I am still not sure why the tail aileron should connect to the rudder pedal though. Unless it's just for stability ?

[Landrotten Highlander]

Hi Mike,

I got a bit confused as to why the ailerons (i.e. the control surfaces on the wing tips) are connected to the rudder, so I did a (very short) bit of searching on google.

This picture is the closest I could find to a restauration of a Sopwith camel.

 

 

I have labelled the individual controls.  As you can see, the Rudder controls are attached to the rudder itself, the Elevator controls are a closed loop system, apparently attached to 2 pulleys just above the rudder controls.  It is not 100% clear, but I think that the rudder pedal can rotate, whyle the pulleys are attached in a fixed position on the outer shaft of the rudder assembly (a bit like fitting a light on your bycicle, you do not attach it to the shaft that connects your steering bar with the front wheel, but with the shaft housing).

 

As I understand it, the elevators cables are not shown in this picture.  They should be attached to the grey 'handle' seen just above the 1st ''R' from 'Rudder-Right', and are also in a closed loop system.

 

Please, anybody,  feel free to correct me if I am wrong in my perceptions.

Hope this helps,

L.H.

 

P.S. I have re-read your previous post, and my reason for confusion is your use of 'tail aileron' to indicate the 'elevator'.  My bad.

 

P.P.S. Link to the pictures above: http://www.johnsshawaviation.co.uk/wordpress/sopwith-camel-f1-2/sopwith-camel-reconstruction/sopwith-camel-metalwork-parts/sopwith-camel-construction-upper-wings/

Edited November 19, 2017 by Landrotten Highlander
adding p.s.; addinng p.p.s.

[Mike Dowling]

Wonderful ! I think your summary is correct. On the model those pulleys are just imitations on the rudder bar but do not move. On the restoration you have found the pulleys are free to rotate which I guess would not really interfere with the rudder bar as such. I suppose such is the limitation of a 1/16 model which isn't really supposed to work anyway but just look the part.

 

Thank you though for your labours - a useful piece of research which has helped my simple brain !

[Mike Dowling]

After a whole afternoon of struggling I managed to get all the control wires to and from the elevator (I stand corrected). Sadly despite my efforts it hardly moves at all with the stick. I did add a couple of tiny metal pieces to the bottom pulleys to stop the cables coming off (John)  in case it made a difference but it didn't. I think there is just too much flex or maybe stretch in the thread provided or just too many places the cable can manage to move between the stick and all the places the cables pass through. The only thing I could think might help is if I glued the thread in the elevator horns instead of letting them run free so that at least part of the cable is fixed somewhere else. Any thoughts people ?

[Landrotten Highlander]

That is how it works in real life when your control cable is on a 'closed loop' system.  Both ends of the cable are attached to the stick (input for control), then a specific part of the moving surface - e.g. one lever arm fixed to your moving surface (i.e. elevator horn) (output of control) - is fixed onto the cable at the desired position.

 

Thus when the control stick is moved one end of the cable is always pulling on your surface, thus it moves in the desired direction.  I think in your case a drop of C.A. to connect the cable to the elevator horn should do the trick.

 

Slainte

L.H.

Edited November 19, 2017 by Landrotten Highlander

[Mike Dowling]

Thanks again Slainte, maybe I will try that tomorrow but to be honest I am not expecting much. I must keep telling myself that this is a non-flying model !! I can't try it tonight because I managed to knock one of the machine guns off during my labour and that is now drying !!

 

It does surprise me, not being a 'flyer' that the cables actually leave the fuselage at the rear. I thought they would all be enclosed but I suppose - thinking ahead - that they will also be exposed between the upper and lower wings so maybe not so strange. It will make my idea of covering the plane on one side much more difficult.

[Canute]

Mike, back then a lot of the control mechanism was exposed. We got smarter and built the control system on the inside of a metal aircraft. Nowadays, we have fiber optics going to the control cylinders of the flying surfaces.

[Mike Dowling]

John - another question! The instructions say that the gap between the lower wings should be 1&13/16th inch. This will leave a small gap each side of the fuselage. It looks on your log as though you had the lower wing spars really close together in the metal joiners which would make the wings quite snug. Which should I do ? Go with the measurement or the snug fit?

 

 

[jablackwell]

I measured the width of the fuselage at the joining location for the lower wing.... then set that accordingly. The gap in mine was a tight fit. Note that you need to place a metal fittings (landing gear struts) between the wing's inner most rib and the fuselage. In my build, the fit was too tight, so I had to carve then file away a notch for the gear struts to slide into.  It worked. 

~j

[Mike Dowling]

Thanks for that, seems I need the gap so I will stick to the instructions.

[Mike Dowling]

I have been a busy boy !

 

I did try gluing just one place on the cables but alas it didn't work. I think I know what the problem is - where the cables wrap round the rudder bar they just get stuck so there is nowhere for the rest of the cable to go. Never mind, I tried. 

 

Anyway I tried to take some pics of the cables but the poor camera didn't know what it was supposed to focus on but at least it shows that I did put them on.

 

I have also cut my lower wing in half (nervous or what?) then rejoined it with the necessary angle and finally glued it on. The beasty is really beginning to look like an aeroplane at last.

[Mike Dowling]

Well now I have a problem !! The undercarriage struts require left and right parts and I have two the same !! The cabane struts have 4 struts and I only have 3. So, I am stuck. I have emailed modelexpo but as yet no reply. What to do?

 

I wonder with the undercarriage struts whether I can cut the tops off, turn them round and stick them back on. Does anyone know if you can solder brittania metal or does it just melt? I might be able to use epoxy but it won't make a very strong joint.

 

Ideas people, ideas ?

[Mike Dowling]

John, when you made your wooden wing struts, did you take your measurements from the plans or the instructions ? There is quite a big discrepancy between the two.

[jablackwell]

1 hour ago, Mike Dowling said:

Well now I have a problem !! The undercarriage struts require left and right parts and I have two the same !! The cabane struts have 4 struts and I only have 3. So, I am stuck. I have emailed modelexpo but as yet no reply. What to do?

 

I wonder with the undercarriage struts whether I can cut the tops off, turn them round and stick them back on. Does anyone know if you can solder brittania metal or does it just melt? I might be able to use epoxy but it won't make a very strong joint.

 

Ideas people, ideas ?

That's unfortunate: just call back to the folks at Model Expo, and they'll take good care of you. I would resist cutting and soldering Brittania Metal, but it can be done if you want to give it a try.

 

~j

 

[jablackwell]

34 minutes ago, Mike Dowling said:

John, when you made your wooden wing struts, did you take your measurements from the plans or the instructions ? There is quite a big discrepancy between the two.

The length of the struts will depend on the placement and angle of the cabane struts. Make sure these are properly placed and angled out appropriately to match their attachment points in the upper wing. Once those are in place, you can attach the upper wing and check into the length of the interplane struts. These came out very close to their planned size for me, maybe a mm off. You have to cut them a little long in order to file them to a wedge fit into their parts CAW42. They should be tight, as in they will "lift" the lower wing a bit and they will attempt to pull down the upper wing onto the cabane struts tightly. They shold not bend the upper wing... that's too tight ;-)

 

~john