Martyn K

Day 2 Cracking on with the fuselage. SLEC fuselage jig in use, one of the best purchases I have ever made. No bananas here. This went together very quickly as the formers had all been dry fitted yesterday. All clamped up and the top longeron fitted and left to dry for a couple of hours. The fuel tank bay has two dummy formers delimiting the hatch. This will be boxed in with 6mm balsa as it needs to be strong enough for handling Next job was to start work on the planking. I did consider a foam and veneer deck but have never been too happy with my foam creations in the past. Coming along but it's fairly slow as expected. May get the decking finished tomorrow evening, if I do I'll park this and start on the tailplane and fin which I will need fairly soon. Fus is still in the jig as it is possible to induce a twist when planking. I speak from a sad experience. The planking around the front of the fus has been completed and the cockpit floor added. It will be trimmed back and sanded to shape tomorrow. Hopefully, I will lose about 1/32 balsa in the sanding process. More to come. Probably not much will happen tomorrow though as its grand daughter minding day which is usually pretty exhausting..

Making a start yesterday... Day 1 of the Mystic build. The sides are from 3mm balsa with ply doublers front and rear with strength from spruce longerons and rigidity from the formers. I start most of my models around the firewall and the fuel tank bay. Building this model I have made one difference. The fuselage sides were joined from 2 lengths of spliced 3mm balsa but not cut too shape. One edge is trued and the upper longeron and ply doublers added. The position of the formers is marked, they are dry fitted and this defines the location of the lower longeron. Once the glue has dried the excess 3mm balsa is then removed. Much easier than trying to pin prick through from a plan. Have to admit it was made easier because the wing cut out and straight rear fuselage lines are very easily defined. The front formers added (the parallel section of the fus) making sure its all vertical or horizontal as appropriate. Dry fit of the rear formers. This set the position of the lower longeron and the sheet then trimmed back to size. All the formers need their slots opening slightly but this ensures a really tight fit if doe with care. Other side clamped into position and left to dry overnight. Front former is offset to build in some right thrust (3 degrees) Tuesday, I add the rear formers and the top decking which is planked.

A couple of years or so ago, I built a 40 sized Mystic which I still rate as one of the best flying models I have ever had the pleasure to fly. I was asked by a few people at the time whether I was going to do a larger version At the time I planned to do a 68" span version for a piped 60 and drew up a plan based on the 40 design using the same basic construction and dimensional relationships. However, time and other projects took their toll and the Mystic 68 was side lined. However, recently, I have been asked again whether I would do a larger version and my CAD systems had the dust shaken off them Hanno Prettner built several versions of the Mystic, larger ones for 120FS power but eventually opted for a 60 sized 2 stroke of about 68" span. The 68" span version needs a powerful motor. Hanno was very fortunate as he had access to the most powerful 2 stroke engines available, made to his specification by OS. These motors do appear on the second hand market as collectors items but the price tends to be astronomical.. A cheaper alternative was required. I have been quite impressed with the OS55AX at UKCAA events. They seem to have adequate power and will happily fly a Curare with oomph to spare, providing the airframe is kept light. A heavy airframe, a long vertical manoeuvre and an under powered airframe is not pleasant to watch, So I redrew the plans (actually shrank then by about 3 or 4%) to drop the wing span down to 64" span with the idea of using OS55AX with standard silencer but with an option of using tuned pipe if others wanted to put either a bigger motor in or simply add a pipe to the OS55. After quite a lot of work this materialised. I then made the mistake of publishing this on the UKCAA group page on Facebook. This seemed to generate a great deal of interest - especially from South America where I have had many requests for copies of the plan and the DXF files. Now, I have no intention of making any money from this design, its Hanno's design and it would be wrong to profit from it. However, if the model is a success then I'll make all the drawing freely available via the UKCAA website. So, 2 sets of parts were ordered from SLEC, one for me and one for one of the UKCAA members who also wants to build one to prove the plans. I am going to keep one component ahead of the other Martin who will work from my annotated and corrected noted/plans. SLEC have agreed to keep the parts on file (which are the 3mm lite ply parts only), there are some additional 6mm and thin ply parts needed but these are not too difficult for the typical builder. I am hoping this will be a quick build - it has to fit in with the Fury build which is currently waiting for paint.

Now, That would be very useful... pretty please...

Mine arrived yesterday as well. Thanks Richard   Won't be starting it until the New Year though. Need to get the Fury finished and I also have a classic F3A that I am kit proving as well   Martyn Edited By Martyn K on 02/12/2020 11:56:15

I renewed this evening. No problems at all. Martyn

Coming along very nicely Andy. I have never had to choke a FS yet. In fact the most difficult job is stopping them from flooding when inverted. They use fire up after a few seconds on the starter Martyn

I am going to go for one of the first UK mustangs, X-XV Probably won't make a start until thf new year.

Thanks Colin This one is deemed to be a learning exercise. Trying to get it as right as possible (for my limited skillset). A lot of rework is slowing me right down but there is no rush.. Edited By Martyn K on 23/11/2020 21:40:45

A bit more progress. All a bit slow because these bits are slow going. Managed to sort out the technique for making my stitches. Using the frame shown earlier, add a layer of klingfilm then a layer of lightweight tissue. Tissue to stretched tight using masking tape to secure. The thread is wrapped around the pins at the side of the frame then tacked into place on the tissue using paste (clear paper glue from hobbycraft) and allowed to dry. Takes about 24 hours at room temperature. Next bit came from experience. One coat of dope over the thread and tissue or some of the 'stitches' will fall off during the trim process. This kept it all nice and secure. Then simply trim the strips and dope them down. Still a slow process but much quicker than doing the stitches individually. SO the stitches went down (top surface only) - these were about 4mm wide, equating to 1" stitches on the full size. When dry I stripped some lightweight polyester tissue rib rapes - about 6mm wide and doped these on top. At this point, the whole lot is pretty invisible. No photos. A coat of grey primer identified a few places where the tapes hadn't stuck down so dope was rubbed in with the fingertip until all the bubbles disappeared. 24 hours later a thin coat of silver applied. I am using 'proper' cellulose paint from my air touch up gun, applied fairly dry. No runs at all. The result looked like this. The paint is a bit patchy as expected - its a thin coat - but the stitches are a bit prominent. The lighting is set so it shows how bad it is. The tailplane was actually a lot worse mainly because I made a real hash of the rib tapes so I have stripped the covering off and redone the top surface of the tailplane. One thing different though, I have applied the stitched strip with the stitched downwards and the tissue on top. Hoping that the extra layer of tissue will help lose the obvious un-scale like bump. Underneath, the rib tapes look quite nice Very subtle. Pleased with those.. What I think the problem is that the tissue isn't shrinking enough over the stitch, causing a ridge. Polyester tissue is heat shrinkable so I am going to go over them with an iron in the next day or so and try and nip them up a bit. If not the covering will come off again and I'll try again with a thinner thread but I don't think the thickness of the thread is a problem. The fuselage has also had a bit of work done. The very smooth hatches immediately behind the cockpit are apparently painted fabric covered ply. I decided to use lith with the hatched cut out and then sanded down on the two short edges so there is a small gap. All sanded and roughened then painted. These appear to have come out quite well. Quite pleased with that. Its starting to look like it may fly one day More to come in dribs and drabs. Martyn