discussion SE5a CONSTRUCTION BEGINNING TO . . .

[wonwinglo]

Very strong and practical Grahame,you have crammed a lot of practicality into a small space.

Can I ask where you obtained your carbon fibre tow material plus the rods ?

Also where the rods enter the centre section do these go just into the timber or is this area sleeved as well ? so the grub screws just sit screwed into the hardwood block ready to wind down,very clever,have I got that right ?

 

[Greyhead]

Well the break in the weather means the caravan is on hold for the time being.

Barry

I got the carbon tubes from www.carbonology.com and I must say they were very helpful; the tows are available from our local model shop. I haven’t sleeved the wood blocks because when the screws hold the wires there will be no movement hence no wear, I hope! You’ve got the idea correct, once the top sheeting is in place the only visible evidence of the grub screws will be four 1mm diameter holes and similarly for the bottom wing.

Grahame

 

[Greyhead]

The jig is mainly made from ¼ square balsa using plenty of braces to ensure stiffness; it’s got to hold the centre section rigidly in place whilst the cabane struts and bracing wires are fitted.


View attachment 262461


The jig in position on the fuselage. It will be held more securely for the final fitting.


View attachment 262462


The initial fitting of the cabane struts is the check that they will actually line up with the fixing points.


View attachment 262463

 

[wonwinglo]

***Details have been added to the Modellers Resource Directory under Carbon Rod & Tube supplies.

Well the break in the weather means the caravan is on hold for the time being.Barry

I got the carbon tubes from www.carbonology.com and I must say they were very helpful; the tows are available from our local model shop. I haven’t sleeved the wood blocks because when the screws hold the wires there will be no movement hence no wear, I hope! You’ve got the idea correct, once the top sheeting is in place the only visible evidence of the grub screws will be four 1mm diameter holes and similarly for the bottom wing.

Grahame

 

[wonwinglo]

I like the whole setup Grahame,just out of interest how much upper wing incidence will you add ? just at a guess I would say 3 degrees decalage.

This lost jig technique can be used on any biplane model and certainly takes all of the guesswork out of everything.

 

[Guest]

Barry,

I added the details of Carbonology.com to the Resource thread a while back, it was them I got the Carbon Fibre from for the chassis for the last Car I built, and as Grahame says, they are extremely Helpful and their prices aren't too bad either.

Still I suppose a 2nd recommendation from us on here won't do them any harm !!

Grahame, that is excellent work....I am enjoying this thread immensely.

Regards...Mark.

 

[Guest]

The more I see this build progress the more I realise that you are almost following the real construction techniques with so many aspects of the job.

Ths is one model where the thought and planning is as important, if not more so, than the building itself.

Superb.

 

[Greyhead]

Everything on the Se5a seems to be at 5º; dihedral, top and bottom wing incidence and even the tail plane incidence. The tail plane looks a bit odd set at 5º but on my previous Se5a I set it at 0º and ended up having to use a lot of down elevator for level flight. That’s one of the reasons I made the tail plane incidence adjustable on the Elf and this model will certainly have it adjustable, I’ll decide what angle to start with at a latter date!

I had an idea that I’d got the details for Carbonology from here but I wasn’t certain, I just copied the URL from my favorites (uck!! But it’s the way Microsoft spell it) in my above post.

Thanks to all who have posted positive feed back.

Grahame

 

[wonwinglo]

Same as the Stampe SV.4,effectively the flying angle coupled to the tailplane as governed by the wing incidence also takes care of the engine downthrust,it is a good system which works well on biplanes.

Adjustable tailplane is certainly a must,I always wanted to try in flight tailplane trim via a threaded rod screw jack,a real luxury.

 

[Greyhead]

Having confirmed that the lower fixing positions are correct the cabane struts are cut in half. It’s far easier to do the bending and drilling for each end of the struts separately then any discrepancies can be catered for when the two halves are joined, I don’t kid myself that they’ll be perfect first time!


View attachment 262464


The lower tube has a short length of smaller tube soldered into it to form a spigot for the top tube. The pin through the joint isn’t primarily to strengthen the joint but to stop the balsa cladding, which will be used to streamline the cabane tube, from twisting but it also makes sure that the inner tube will stay in place as the top tube is soldered to it.


View attachment 262465


A small screw holds the cabane strut to the centre section, those hard wood blocks are definitely multi propose.

 

[wonwinglo]

A very wise decision Grahame to split the tubes,from past experience it is virtually impossible to get everything lined up on a single strut with accuracy,I often wonder how De Havillands made up their centre section struts,probably jigs set up ?

The cladding is not easy either to do successfully,I have tried lots of ideas including built up 'L' shaped pieces glued either side then shaped to streamline section,the spigot is a good idea as well,nothing worse than the cladding migrating around the inner tube which it always seems to do !

Another way is to use one of those delightful little router tools that Hobbycraft sell,the routed section is then pushed onto the tube using slow drying epoxy,a plug strip then fits into the slot from the rear,when all this is dry the whole lot is sanded to aerofoil section nicely.

No doubt that you will have your own way of doing the job which I look forward to seeing with interest.

 

[Guest]

very nice! keep it up!

 

[Greyhead]

Before soldering the cabane struts together all the bracing wires need to be in place, in fact joining the tubes will be the very last job to be done.


When making multiple, or as in this case “handed” brackets, your computer is an extremely useful tool, first draw out the bracket, scan it in, copy and paste the image after “flipping” it if “handed” brackets are needed then print out as many as required. For small brackets such as these I print them onto self-adhesive labels.


View attachment 262490


To make sure that the brackets will fit I made some test pieces from scrap Lithoplate, as this is dead easy to cut and bend, then the labels are stuck to the sheet material, in this case brass, for the final brackets to the cut.


View attachment 262491


The final shaping will be done with a combination of Dremel and hand files.

 

[wonwinglo]

The late great Col Palen from Old Rhinebeck near New York who used to restore and fly old aeroplanes,once said 'If you have the brackets and metal fittings of any old aeroplane,then you can build a new one from the ground upwards,even if the airplane has burnt to the ground then we can salvage anything made of metal and use it again' Grahame your picture reminds me of this wonderful man who gave us so many Word War 1 machines to enjoy even today.

I use your system to build small models,first I transfer the parts onto stickyback film exactly the same as you do,then place it onto the balsa rolling it on with a p[rinters roller and cut out the parts carefully,the sticky film actually holds the wood grain together,then you just peel it off and hey presto,a nice clean set of parts ready to build.

A little bit more about Palen to show his devotion,after a hard day restoring the collections machines he would walk right across the wood surrounded airfield to his cottage the other end,have his tea and then build scale rubber driven model biplanes to fly on his front lawn,I just thought that you would enjoy that unusual story.

 

[Greyhead]

Barry

A nice story, thank you for sharing it with us!

When cutting the large “square” holes in the ribs (see post #38) I stuck Selotape on both sides of the rib because the cut is very close to the edge, as you say this holds the wood together, after carefully removing the tape I apply some thin cyano which really strengthens the wood. You can cyano the wood first but this makes the cutting a lot more difficult.

I should have included this tip in the post but you tend to assume that everybody knows these things; another thing I’ve just realised is that I blithely said, “using the “sandwich” method”.

Basically this means using the 2 outer ply ribs as templates for the inner balsa ribs, which are cut as blanks, held between the outer ribs and sanded to shape. When I get to the wings I’ll take some photos of the process and do a Tutorial thread.

 

[wonwinglo]

Yes please do post any info on the time honoured sandwich method Grahame,also whilst on the subject of adhesive tapes etc, and their uses in modelling here is one that I discovered by accident when I cut my finger,I reached for that wonderful material called 'Micropore' to stop the bleeding,then by accident I touched a bit of cyno,the Micropore immediately turned into a solid hard lump and really gripped my finger,after prising off the moulded material I realised that this had other uses,if you need to wrap wire to wood or strengthen up a particular area then simply flood with cyno over the Micropore,within seconds it bonds almost anything,very useful especially in difficult areas.

 

[Greyhead]

The brackets for the cabane bracing wires have been soldered to the top sections of the struts; all the bracing wires will be cut to the correct length and soldered in place with the centre section held by the jig.


This is a photo of one of the rear struts.


View attachment 262492


Luckily the end fitting for the side wires are hidden inside the cabane fairings with just the end showing so they can be simple tubes.


This shows a general view of how the struts and bracing wires will go together.


View attachment 262493


The front and rear bracing wires are a bit more complicated as the end fitting is visible. Once the wire is the correct length with both ends soldered in place the pin will be replaced with a short length of piano wire and the whole lot soldered together.


View attachment 262494

 

[wonwinglo]

Once again Grahame lots of thought gone into this area alone,the first thing that strikes me is the immense strength of the centre section strutting,just like the full size S.E.5A which despite being shot up held together well.

Although you make it look easy I bet that getting this little lot together took a bit of thinking and working out.

Note by the way,that wires have given way to streamlined rigging on modern day reproductions,to meet the stringent airworthiness requirements demanded today.

 

[Greyhead]

Barry

You’re correct on both counts:

The cabane assembly is, or will be, very strong. My advice for what its worth is “never scrimp on the cabanes”. Experience has shown me that biplanes fly better if the top wing remains attached to the fuselage!

The brackets did involve a lot of exercise for the old grey matter; and I still got it wrong! I failed to take onto account the fact that the brackets are folded back on themselves around the pin thus effectively doubling the thickness. I soldered them to the cabanes using the 2mm fixing hole as a refence then found that the centre section wouldn’t fit so had to unsolder them and refit them lower (this was more of a chore than it sounds!!); you can clearly see this in the first photo in post #57.

Just to make me feel worse I’d purposely carried the “doubling” further then strictly necessary to level up with the flattened tube that makes the other bracing wire attachment.

 

[Greyhead]

With the jig and centre section firmly held in position using various clamps the bracing wires are cut to correct lengths. Now would appear to be the time to solder the assembly together but there is a problem.


View attachment 262495


All those wires will make it very awkward to complete the fuselage top decking but if the decking is completed first it will then make the fitting of the cabanes more difficult!


I’ve decided on a compromise; I’ll finish the front section (the tank cover) as this has a lot of detail with straps, fasteners and the trough for the Vickers machine gun etc. and then finally solder the cabane assembly together before completing the decking back to the cockpit


View attachment 262496


The end fittings for the front and rear bracing wires are soldered to the wires because with the pins removed they easily take apart.