The P.1121 get's it's feet wet

[Gondor]

After trying very hard to get parts of the Airfix E.E. Lightning intake to fit into this build, I am giving up on those parts. I have decided to try something outside of my comfort zone. To that end, I have gone very old school, so old school that I have gone back to 1977, when I was actually at school. As that is way back at the dawn of creation, or near enough, I had to ask for some help from one of the mechanical design guys at work, who helpfully sent me a link to a video about how to do what I was after.

So this is what I have just been doing.



It's a little difficult to follow, but the gist is that to model the air intake ends up as a truncated cylinder when it reaches the compressor face, as can be seen below.



The front end of the intake is, of course, nothing like a cylinder, truncated or not. So I needed to find out what shape I need to cut out of a suitable material to create the truncated cylinder where it meets the compressor face. The drawing at the top of this entry provides that information.  I will use paper to begin with, so I have a rough idea of the final shape, then I shall transfer the shape to brass shim. At the end of the process, I hope to have a nice and fairly smooth intake and still retain hair on my head and not be suffering from concussion from banging my head off a wall or some such object.

Gondor

[frank2056]

There are a couple of online shroud/truncated cone calculators that generate pdfs that may help. This one is pretty clean - under Transition Tool The PDFs from This one are a bit messy but still useable.  The original Shroudcalc site is long gone but this siteunder the Transition/Shroud calculator will just generate the values and angles needed.

[Gondor]

There are a couple of online shroud/truncated cone calculators that generate pdfs that may help. This one is pretty clean - under Transition Tool The PDFs from This one are a bit messy but still useable.  The original Shroudcalc site is long gone but this siteunder the Transition/Shroud calculator will just generate the values and angles needed.

Thanks for the links. They may be useful for something in the future. The shape of the intake is similar in idea to that of an F-16 intake though, so the intake  is not conical in shape. If I had a bit more oomph rather than the head cold I have, I would be posting pictures of what I am doing.

[Gondor]

I managed to get enough enthusiasm to push forward a bit with this build. Now I have the curve for the compressor end of the intake I copied the curve onto a small piece of paper and cut the length roughly to size.



The above picture is not to scale. The rectangle represents where the nose undercarriage bay intrudes into the intake. As can be seen below, the darker lines show the top of the intake and the rough position of the resin nose undercarriage bay.



The next thing for me to do is to try to work out how the intake deformed from a cylinder into the shape of the front of the intake, minus the width of the undercarriage bay. This is where it gets really fun 

Gondor

[Spino]

Careful posting too many sketches, some of us are only just recovering from getting brassed off, no good to make us sketched off too     

Honestly though I applaud what you're doing with this, I don't think I'd ever have the patience for it.

[Old Wombat]

It's all lookin' a bit sketchy to me! 

  

[Gondor]

It's all lookin' a bit sketchy to me! 

  

I'm hoping to draw people into the build 

[Old Wombat]

It's all lookin' a bit sketchy to me! 

  

I'm hoping to draw people into the build 

    

[NARSES2]

I sometimes just sit here and ..............................      

[Gondor]

I sometimes just sit here and ..............................      

Well, as there is no BBC Light Entertainment, you have to get your laughs from somewhere.

[Gondor]

I think I have a plan,



Or at least a shape to cut out and try. The line is the top centre of the piece, so I know which way is up, at least I needed that while playing around with the paper template.

Gondor

[Gondor]

I have managed to use the template to cut out the brass section by using PVA to stick the two together. However, it is too late in the day for me to braise the brass into a loop at the compressor end. So, in the meantime, here are a couple of pictures of the paper template around the nose undercarriage bay to show roughly what the finished item will look like.

The nose of the aircraft is to the right in this picture.



And head on, looking towards the tail.



As you can see from the above picture, the paper was deciding to do its own thing rather than what I wanted. The brass should be a bit more cooperative, I hope.

Gondor

[Gondor]

In the early evening, I received a package from Amazon of a set of three self-gripping tweezers with fibre grips, ideal for holding things together while heat is being applied to them. So, out with the soldering iron.



A bit messy, but other than the pictures in this post, the joint will not be seen again. It actually went together very easily, thanks to Heather Kay on Britmodeller, reminding me of how to braise the parts better than I had been doing so.

Side view



Fitted around the nose undercarriage bay. Compare these two pictures to the ones with the paper template.



And a view up the snout as it were.



If actually fitting the rest of the intake goes as well as tonight's work did, I will be in danger of finishing inside the deadline. 

Gondor

[Gondor]

More holes, or bigger holes in the fuselage. Hopefully, that's the last in this section of fuselage that I need to make, other than for where the supports for the wing fold mechanism will go.



Other than tidying up the larger holes for the engine air intake, it should be a case of starting to glue some plastic together. I am going to have to come up with a new spine for the model; the air intakes on it are much further to the rear for the naval version than from the land-based version, so they had to come off. The biggest problem is around the nose intake. There is so much plastic removed now that I expect there to be cracks form and sections trying to break off. Once the nose undercarriage bay goes in, things should start to become far sturdier and more aeroplane-looking rather than a box girder bridge.

More tomorrow, I hope.

Gondor

[Gondor]

Slow progress. I'm starting to think that I will not have this completed in time for Telford, or it will be ready in time for Telford, just not this year. 

There is simply too much for me to get done with my build speed for it to be complete this year. I am thinking of taking it with me as far as I get it to show off what I have done to anyone who is interested.

However, I have started to glue parts of the fuselage together



I have supported the inside of the joint between the undercarriage bays with a strip of 10 thou plastic card.



The next step will be to fit the nose undercarriage bay and then fair it into the remaining plastic around it. After that, it's onto the intake trunking and making that fit to the engine intake.

Gondor