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

[Mike Dowling]

Hello Folks and welcome to a new build.

 

I know it's not a boat but there do seem to be an increasing number of us widening the horizons so to speak !!

 

Whilst this is supposed to be a kit build from Model Expo (Model Airways), if it wasn't for the huge number of cast metal pieces I reckon it would rate as a scratch build !! You will see what I mean when you look at the box contents. Not a lot for what is a pretty pricey model.

 

Included are some laser cut parts, mostly the wing ribs, A big bag of metal pieces, some separate wood, 5 sheets of 1/1 plans, a parts list 28 page instruction manual. Oh and the box of course !!

 

I have also included a picture of some Hasegawa 1/16 Camel bits that I acquired !!

 

My reason for acquiring same was for my cunning plan (!!!) which is to half cover the model and leave half as a skeleton so I needed some bits like the engine cowl to cut in half later. I also got the Hasegawa seat as it looks so much better than the supplied effort.

 

So, here we go. I reckon I am going to need a lot of help so the more watchers the better.

 

[JohnReid]

I built this model as part of a diorama that I was working on for the Canada Aviation and Space Museum in Ottawa. Cheers! John.

[jablackwell]

Hi Mike,  Found you!   

Looking forward to your build here. 

~john

 

[Mike Dowling]

Hi John, thanks so much for joining in - I am going to need you !!!  I have spent the afternoon cleaning up all the swarf etc from the engine pieces, they are not the most brilliant castings I have seen. I have also polished them to remove the coating on them so that I hope they will glue OK. I will have a go with CA as otherwise I can see myself mixing epoxy batches forever. Good start - my new Dremel packed up just after I started, lucky I have a silverline version as well !

[Mike Dowling]

Well folks,

 

I have completed stage one and built the engine. I can't believe something so small is made up of 114 pieces ! Yes I am truly sad and counted them ! I did decide not to use thread for the spark plug leads but used thin wire instead. Whether it was a good idea or not I don't know. 

 

I am puzzled, not knowing anything about aircraft engines, as to how the beast ran at all. I thought tappets etc on an engine had to be bathed in oil but these would have been exposed. Amazing.

 

Anyway, some pictures for you, sorry they are not very good but you should get the idea.

 

 

[Robin Lous]

Nice start! 

8 hours ago, Mike Dowling said:

I am puzzled, not knowing anything about aircraft engines, as to how the beast ran at all.

For me...part of the fun of a build is the search for more information about what I'm building.

I tend to go completely over the top with that. Not only many hours of internet searches for the real thing and other builds of the same, but also books and when not too far away...a museum where I can see it.

Has a downside also...I always find things to improve and that can be frustrating, specially since I'm not overly handy and often don't have a clue how to do it. 

 

[jablackwell]

Hi Mike,

Pics of the prop for you. Counterclockwise rotation when viewing the nose of the craft (as if it was going to run you over ;-) (figure 5 in the instructions). Their prop is thinner than mine (and likely more accurate). The side view shape is correct. I could have spent more time sanding and sanding and sanding.... With this engine, the prop was attached to the engine solidly, and the WHOLE engine rotates. Amazing to see in real life actually. Very noisy things.  Here's a vid:

 

 

~john

 

 

[Mike Dowling]

Thank you so much John - a great help.

[Mike Dowling]

After a while (!!!!) all the spars have been capped. What a job !! And I didn't break any.

 

 

[jablackwell]

Nice!  Those ribs are so time consuming. There were points when I was almost just DONE with the whole model thanks to these ribs. Well, now you are on your way!  

~john

 

[Mike Dowling]

I know what you mean John, and I thought ships were difficult !!

[Mike Dowling]

Help !! I have looked at propeller pictures until blue in the face and I still can't figure it out.

This is what I have sanded off so far - it is so difficult to show in pics.

I have taken one from the front, one side, the back and then the other side and lastly one sort of sideways.

 

Can someone please tell me what I should do next ? Ignore my pencil marks as they are probably wrong.

 

 

[jablackwell]

Hi Mike,

 

The prop is looking good. The side view looks perfect. You have done a good job keeping the profile to the right shape and dimension. Now to the angles of the blades.  I find it difficult to see what your images are showing me in terms of 3D, so I will try words.

 

The prop spins such that the rounded edge of the blade is the leading edge. It might seem like that is backwards, but it is true. So let's look at the last pic you posted.  The left hand side, towards us, is the curved edge and is the leading edge of the prop. On the right side, this curved edge is up top of the frame: that is the leading edge for the other side. The trailing edge is the flat edge, without any curve. 

 

Looking at the front of the prop, you want to sand or carve (or both!) away the wood on the flat edge of the prop, the trailing edge.

Looking at the back side of the prop, you want to remove wood from the curved edge side of the prop.

Doing this will create an angled propellor blade that pushes wind behind the plane as the prop spins. 

 

Maybe this helps?  Hard to do in words and in 2D images. 

 

~john

[xken]

Try this for a little reference.

 

http://www.wwi-models.org/Images/Foran/Hand_Carved_Props/index.html

[Mike Dowling]

Thanks John, you are quite right, it is very difficult to explain in words and the pictures only help a small amount, but I do understand the physics if you see what I mean.

 

Ken, your pictures are wonderful but the Sopwith propeller is not quite the same as the ends are not 'tapered' on both sides, only one.

 

Do you both think that I need to take away more wood from the angles I have already started and then turn the prop over and remove wood from the straight side ?

 

That would sort of be the same as I have done on the front but in reverse ?

 

Am I getting this right yet ?

[jablackwell]

Hi Mike,

Yes, more wood needs to be removed. The shape and patter you have are correct, but the blades need to be thinner. The front edge will be more rounded than the trailing edge from a cross-sectional standpoint (and also longitudinally which you know and is looking good now). The trailing edge should be thin as can be. All this while maintaining the really nice side-view shape that you already have. Not sure if I am making sense.... I kind of wish they had provided a series of cross-section sketches for the prop shape.

~john

 

[Mike Dowling]

Yes.I wish that as well. I also wish I had an old propeller around to give me the right 3d look and feel.

 

You say the trailing edge should be as thin as poss but is that the straight edge ? If I take a lot more wood off, won't I lose the profile as I have it at the moment ? Or is it just me and I can't see the 2d drawing in 3d ?

[jablackwell]

The trailing edge is that flat edge, the straight one. If you think of it as a cross section, the point where your edge is not is correct. You just need to thin the blade out. Imagine it as a wing.... it has a airfoil shape to it. The side view (profile) should remain constant. 

Check out these images:  http://www.johnsshawaviation.co.uk/wordpress/sopwith-camel-f1-2/sopwith-camel-reconstruction/sopwith-camel-propeller/

 

~john

[Mike Dowling]

Oh I am sorry to be a pain. The photos are great but, at the moment , with my prop lying on its back, I have shaped sloping ends each end on one side only as per the diagram in the instructions. If I thin from the front I will lose that sloping end shape. Do you see what I mean ?

[Mike Dowling]

It just looks to me as though I have started the shaping from the wrong side ?

[jablackwell]

Hi Mike,

No worries - you're not being a pain.  ;-)

The prop should be thinned equally from both sides. So if you have carved away enough from one side, then work on the other. 

The images in that link show just how thin the prop blade should be, and their angle. 

~john

 

[Mike Dowling]

so have I done anything wrong yet ? apart from ( I think ) sanding convex instead of concave ?

[jablackwell]

Nope - nothing horrible :-)  

~john

[cog]

You keep on choosing models where you have to sand ... glutton for punishment ... a wee bit late, but still some more progress to folow ... looking good so far

[Mike Dowling]

John, am I right about the concave bit ? Should it be concave not convex ?

[Mike Dowling]

Great to see you Cog, thanks so much for watching. Don't all models need sanding, maybe not quite so much !

[jablackwell]

14 minutes ago, Mike Dowling said:

John, am I right about the concave bit ? Should it be concave not convex ?

The blade starts thickest at the hub and becomes smoothly thinner to the end of the tips. The blade can't be concave on both sides.... only one side and this is the back side, the side closest to the engine. It is very slight.

[Mike Dowling]

Now I think I get it ! Like a plane wing so it will be slightly convex on the outside and slightly convex on the inside ? If that sounds OK I will get on with some more sanding (!!!) on Tuesday.    I guess, worst case scenario, if I muck it up I can buy one ready done albeit not for a Sopwith !

[Landrotten Highlander]

Not sure if this helps...

 

Consider the wing of a run-of-the mill airplane (civil, not military).  The wing is rounded on top, hollow at the bottom.  The rounded edge points towards where the lift goes (that is a force that 'pulls' the wing upward).

Also, the bit that hits the air first  is called the leading edge, and the other end is called the trailing end.  To ensure easy airflow around your wing, the leading edge is usually thicker and rounded, while the trailing edge... trails to nothing.  Located rougly 25-30% from the length of your wing (as measured from front to back) is the thickest part.

 

Now turn that wing 90 degrees, so that the rounded bit of the wing is now pointing forward (the direction you want the propellor to pull the aircraft = forward).  What is now the back side of the propellor is hollow, while the front side is rounded.

 

So far the easy bit.  Now for the more complicated bit.

The force called LIFT (i.e. the pulling force) is dependant on V^2 (= speed x speed).  So the faster the speed, the bigger the force.  But if the speed goes too fast the airflow around the wing (propellor) breaks away from the surface, and you end up with no lift whatsoever.

Without getting too technical here, the tip of the propellor goes much faster than the root (the bit closest to the shaft).  Given the problem above, it is important that the speed at the tip does not get too big.  To that end the angle of attack (that is the relative angle the windflow has relative to the forward edge of your aerofoil) needs to be adjusted, from pointing forward at the root of the propellor to almost at right angles to the shaft at the tip of the propellor.

 

The easiest way to visualise this is to take a piece of paper.  Hold it vertical, the bottom touching the table in front of you and you facing the writing side of the paper.  Now while holding the bottom edge of the paper in place, twist the top edge of the paper either clockwise or counterclockwise.  That is the shape of your aerofoil that seems to elude you, as I understand it.

 

Because of the material and forces involved, the tip of the propellor is much thinner than the root (so the aerofoil goes from thin at the tip to oval/almost round at the root.

 

Another way of looking at it is to see your propellor as a series of differently shaped aerofoils layered one on top of the other, each aerofoil slightly differently shaped as well as at a slightly different angle.

 

Wishing you good luck.

L.H.

p.s., been following your build log with interest, might tackle one of these things as well....

Edited October 22, 2017 by Landrotten Highlander
clarification of thickest part of wing

[Landrotten Highlander]

extra note, now I think of it.  Do not take the difference in angle between root of propellor and tip as exact.  It is an exageration to help you visualise things.

L.H.