Builder #5: Frank Deeth - email for more information Location: Melbourne, Australia Start date: Officially April 2007 but unofficially about 1995. First flight goal date: Too far away to contemplate at this stage. The Project: Fuselage Fun - July 2011
In keeping with my approach of trying to build a "kit of parts" the opportunity presented, in the form of space on the bench top, to glue up the upper engine bearers. These are monster pieces not unlike the original metal units on that most famous of fighters! I thought it would be a reasonably quick process as I had already "sized" the correct materials a couple of years ago when I had nothing to do one day (Huh? Me, nothing to do??). Unfortunately, I misread the plans and didn't quite get the dimensions right for one of the laminations on both engine bearers. Both laminations should have been full length and then tapered later to the fuselage profile. As a result I had to set up my router with some home made guides to "cut" a splice joint into the short laminations on each bearer and spliced them to full length, to be mostly trimmed off later in the build as they are profiled with the fuselage sides/taper. In the end a job that should have been finished a few weeks back has just had the last sheet of plywood glued on yesterday (12th July 2011). Later, when the fuselage starts going together you will be able to see the taper I am talking about.
Other progress on the fuselage is confined to the carry through beams (mentioned elsewhere in the progress section) for the first four fuselage frames and some of the fuselage bulkheads. I have started at the tail and am working my way forwards with bulk heads as well as working aft from the firewall. This has caused a shift in my plans a little and I have stopped the wing rib construction until the fuselage bulk heads are done.
Check back for progress soon.
I did all the frames for the first four fuselage frames or bulkheads if you will...there are 14 individual side frames that need to be fabricated for the "big four" bulk heads. After doing those and then making a start on frame 18 which is down in the tail (sticking to my tried and true method of starting in the tail and working forwards!) I rapidly lost patience with this part of the build.
Yes, I don't mind admitting I took the easy way out and put in an order with Russ for the remainder of the fuselage frames. The frames are still in the USA and I should be bringing them home mid to late October. This will make a huge difference to the progress with not much outlay in the overall scheme of things. Plus I like to try and keep sending work Russ's way whenever I can!
The other major part of the fuselage base frame is of course those big ol' lower longerons. Russ has recently modified the lower longerons to make them simpler to fabricate. Unfortunately for me I had already started making mine, so I decided to continue with the original plans I had.
They are a challenging component I must say, also bearing in mind there is a left and a right hand so organizing all the parts has been doing my head in a bit. It's the kind of piece that needs to keep going from start to finish, as, if you put them down you might forget the sequence of fabrication you have worked out in your head.
As it was I went to the UK to fly the Spitfire and was gone for just shy of two weeks, this was long enough to have to go back a few steps and figure out what my next move was! Anyway, we are moving forward again now and by the picture below you can see each of the lower longerons is essentially made up of three major components with four or five minors components thrown in at various stages. They look like they will be immensely strong with lots of redundancy built in for good measure! Also visible are the fairly simple upper longerons resting on the main spar along with my fuselage frames 18.
The other pics are a couple of views of three of the "big four" bulkheads. Things are hotting up and this will be an area of major progress soon so keep checking back often. Ciao!
This has now been done of course so there was nothing for it but to just start putting the fuselage together...starting with the base frame!
This unit is basically a boxed up section of longerons and bulkhead verticals that all the curved fuselage frames will glue to, which eventually provide the shape for that magnificent fuselage to be represented in a plywood/balsa/plywood sandwich. The base frame is started out by the sides being built flat on the bench and then jostled into position, in a vertical orientation, upside down, with jig blocks, clamps and temporary structures as required to maintain the correct shape whilst gluing in all the particular cross members etc to hold the basic shape. Then, before the removal of the fuselage from the jig we will glue on, what will eventually be, the bottom surface of the fuselage skins to maintain the required stiffness of the whole fuselage.
The following pictures show the layout of the base frame sides and starting
to get a feel for setting it up vertically. It's been a long slow process,
clamping, measuring, adjusting and figuring the next step. We are slowly getting
there though and will soon be ready to start gluing in all the cross members and
such. The more I progress with this phase of the build, the more I am convinced
that I did the right thing by fabricating spars and such first...this "beached
whale" will be there on the bench for quite a while now I expect! Enjoy!
October 2014: It's been a while since I have updated this section and much has occurred. There is more to follow but I wanted to show these two pics with a few words as it was somewhat of a milestone in the project...doesn't look like much I know, but this close up picture is the symbolic joining of the two fuselage sides at the tail post with the second shot showing the whole fin post/fin spar glued into position. This was the culmination of many hours of measuring, thinking, clamping, thinking some more and so on and so forth until I was happy to start joining the two sides. It has progressed much further since then and I will bring you up to speed very shortly in the area of the fuselage. Cheers for now...
Ok, so now I shall try and attempt to explain the process of the fuselage skinning, it's kinda like I can't do this job, until I have done that one...and I can't do that job, until I have done this other job! After all the frames are in place the last piece of the jigsaw before skinning is the frame 4 bulkhead. This needs to be in place as the bottom curved skin butts up against it. I can't glue it in position until I have drilled the frame to handle the rear spar attachment plates.
There is a picture in this group of photos of the frame being match drilled for one of the four pairs of plates. I couldn't drill the frame until I had the jig fabricated...then I had to figure how to position the jig so it wouldn't move about...all this took up far too much of my spare worrying time with very little doing time until ultimately I started getting browned off about it and just sat down one day and started playing with various positions, clamps, measurements etc, etc.
The old adage here is so true, "sometimes when you are stuck on something the best remedy is to just START!" Well, with this in mind I had figured out a plan of attack pretty quickly and I am more than pleased with the initial results drilling the first few holes. I was able to get the technique down pretty quickly and find I can easily (no time pressure, no stuff ups!), set up and drill a hole in less than 30 mins. I reckon I am getting quicker too so it shouldn't take me too long to do all 100 holes for the spars!
In the interests of keeping things moving along I finally pulled apart and refurbished the seat intended for the front cockpit as well. I guess I could see the fuselage progressing and started to worry I wouldn't have the seats ready to install as soon as possible! As mentioned previously, these are single seat Vampire seats (as well as used in things like Hawker Typhoon and Percival Piston Provost I think?) the seat was washed down with warm clean water and allowed to dry, then 8 coats of "Shellac" (the stuff made from Beatle sweat!) was brushed on. The finish is superb I think and I only need refurbish the metal fittings and the two cockpit seats will be done.
The last picture should be an overall shot of the fuselage from the tail post looking forwards. Starting to get that classic curves look about it! Enjoy! Frank
Along with the last bit of profiling work I am trying to get some of the early fuselage fit out work done as well. Things like the forward and aft elevator bell cranks, rudder cable guides and varnishing an areas that will be hard to reach after the skins are on. Tailwheel mounting is also something I want to have organized sooner rather than later (as I am opting for the fixed gear unit we have quite a bit of development to do in this area, so I don't want to "skin" that area at all until we have it all sorted!). Luckily I have plenty of other jobs to do if I find I am waiting on completion of any commissioned components to be finished.
At the other end of the fuselage I have put my hole drilling jig to good use and finished match drilling all the rear spar attach plates through the rear spar carry through frame # 4 and then glued frame four into position on the lower longerons. It took a bit of fiddling getting frame four in the right position. The lower surface of the lower longeron had to be notched so that the frame would sit at the right height reference the fuselage thrust line, it also had to be the correct distance from the ends of the lower longerons and finally it had to sit exactly vertical, or in other words, 90 degrees to the thrust line. I used my good old trusty mechanical inclinometer, the same one I used when I built my little Corby Starlet! All of this used up many hours of wiggling the frame into and out of position, checking, moving, sanding, moving, checking again etc, etc until I was happy with the position. Ultimately, now it is glued into position, I am very happy with the result and all the time spent was worth it! As previously mentioned it (frame # 4) will then act as the forward limit of the curved lower fuselage skin, below the lower longeron line. So it was an important component that needed to be drilled and glued in place before we can start applying the all important fuselage skins!
Another side benefit I have noticed is the once crowded workshop floor space has actually freed up a little bit as components are now being finally glued to the fuselage permanently rather than laying haphazardly around the shop! The combined firewall and main spar carry through member (frame # 1) has now been lifted up off the floor onto some saw horses and positioned ready to start match drilling the forward spar plates.
The following pictures, in no particular order are: fuselage with all frames glued in place, some various shots of frame # 4 after being jig drilled for rear spar attach plates and the same frame during a dry run positioning on the lower longerons. Enjoy!
Fuselage with almost all frames and stringers etc glued into place. Just a few minor pieces left to do and then varnish and I can start covering with first layer of plywood.
Rear spar carry through member, frame # 4, with the first of four pairs of rear spar attach plates bolted into place, checking for hole alignment etc.
Another view of frame # 4 and test fitting the rear spar attachment plates.
The same frame # 4 with the various drill bits, counter bores and bushes required for the final completion of the frame.
This is frame # 4 with the last of the rear spar attach plates being match drilled etc. Note the block of temporary timber glued to the bottom of the frame. This is so the drilling jig has something to "grip" so it doesn't wonder or vibrate around when trying to drill.
Trial fitting frame # 4 to the fuselage before gluing. It has to pretty much just slot into position with minimum of fuss so that the gluing would go as smoothly as possible. This worked pretty well by taking the softly, softly approach with alignment and fitting, the end result being an easy to fit and align component with lots of help from my brother during a critical gluing operation.
July 8, 2015... A long overdue update! Bottom half of fuselage has been skinned aft of frame four to just ahead of the stabilizer area. Still working on the tailwheel leg mounting, so that area is untouched all the way to the fin post.
As I planned the skinning process I became concerned about how I would offset the scarf joints from the inside skin without seriously reducing the thickness of the 1/4" balsa in some areas...straight lines around curves are basically a series of tangents, if the tangent joins overlap the distance between the inside and outside tangents vary in depth. Anyway, my solution was to incorporated the technique they used on the DH Mosquito...that is to use an infill of solid spruce or plywood, the same thickness as the balsa (1/4") located over each inside scarf join and also over some of the internal fuselage frame structure. For the mosquito I am guessing it was to carry the load of the internal frames and bulkheads all the way to the outside skin. For me it gives a solid point in which to scarf join the skins...probably an overkill but I like things cut and dry!
So pictures attached are fuselage with first layer of skin with "internal" frames and stringers in place and some pics of the balsa infills being fitted and glued in place.
Obviously cutting and fitting the balsa, then gluing the balsa is the first step. Still learning about the "clamping" process for the balsa...I think I've got it sorted.
The second step is I profile sand the balsa as I've found its close to 1/4 but not exact and requires some attention to make sure it's not sitting too high within my various "bays" or "sub panels" I've devised as part of the gluing scheme. Also, because the balsa is a series of flat panels I put extra scores or cuts in the balsa so it "bends" a little more evenly around the fuselage sides. It still is a series of small tangents though and needs some sanding to remove the high spots and keep the curve consistent.
Third step is I use a cheap thick rubber squeegee to spread neat epoxy glue over the sanded balsa panel and thickened epoxy glue to fill any of the gaps between the balsa and the strips of 1/4" solid spruce or laminations. After its dried I sand it all smooth again and use this opportunity to remove any high spots and make sure the balsa panel is a nice consistent curve. Once I've got the ply panel size decided I soak it in a bit of hot water then pre-bend it and allow it to dry. After it's dried, I drill and pin it along the fuselage belly stringer with a couple of 1.6mm nails so I can place it in the same position when gluing, clamping and stapling!
When gluing I use the squeegee again with neat epoxy on the surfaces and I've found it heartening to see that the balsa stays "wet" with epoxy and doesn't soak in so much. I expect that's due to the previous priming of the balsa allowing some epoxy to soak in and help preventing a dry glue joint when I eventually come to laminating the outer plywood skin. The gluing process is completed with a squeegee of epoxy also on the plywood skin and then I use a toothed spatula or trowel (for want of a better term) to spread an even, thickened surface of west system between the two gluing surfaces. It's the kind of thing contractors use to spread an even layer of glue when laying tiles in a bathroom....anyway, I usually spread this glue on the balsa surface for ease of handling, but it could be equally accomplished by spreading it on the inside of the ply skin. As usual with lots of prior prep the last five percent moves pretty quickly and I now have four panels glued in place and only two smaller ply panels to go for this lot. All ply joins are done with a scarf or revers scarf joint as the case may be.
Last couple of pics shows the two smaller plywood bays "fitted" with old X-ray film to get the basic template for the plywood shape and then the resulting plywood panels cut and scarfed and after a soaking in warm water are rigged in a fashion to allow them to dry. This gives an easy going pre-bend that makes the clamping process that much easier to accomplish.
After these next two skins are glued on the next step is to sort out the mounting of the tail wheel and once that is done its home stretch with the remainder of the lower half of the fuselage skinning and balsa, all the way aft to the fin spar, only when that is completed will I be ready to remove the fuselage off the bench. Getting closer everyday, but as usual it's two steps forwards one step backwards!
Enjoy - Frank
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