-
Posts
277 -
Joined
-
Last visited
-
Days Won
10
Content Type
Profiles
Forums
Blogs
Gallery
Calendar
Downloads
Everything posted by John Rickett 102
-
Ron, Be careful taking off the back plate, there's an evens chance a cam could release still attached to it.
-
Steve, Did you wet the sheeting at the tip before applying, it will bend easier when wet though will take longer before the pins or clamps can be removed. The same goes for the whole of the leading edge sheeting, wet one side and you'll quickly see the curve that the wood adopts, this then helps relieve any stresses that would arise when pinning into position. There is little point in sheeting the whole tip, it may offer a bit more ding protection but that's about all. You could perhaps add an intermediate fillet to prevent the covering sagging between the bays. As it is, it will be adequate for the job its got to do. When covering, cover the bottom of the wing first and finish the covering onto the top side of the tip (1/2" will be more than enough) the top covering can then be carried round the curve and attached to the bottom covering....you had pre-planned this already I imagine.
-
Four footholds have now been taken from the plug and the excess dry cloth removed. Each took about 15 minutes to lay up and then a wait of 24 hours before one could be released from the plug and the next one started. The excess depth and length of the plug allowed for easier handling but most of the fibreglass needed to be cut away leaving quite small parts to be glued into the wing, this will be done once the wing is glassed. The combined weight of the castings is 5 gm, I’m well pleased with that as I doubt another method would have yielded a similar practical, lightweight result. I had assumed that the bases of the footholds would have been at the same angle, parallel to the ground, on closer inspection it appears they are different, the rear ones slope upward more than the front ones. The front ones can now be made deeper………an exciting revelation for an anorak modeller. Blue foam would be a suitable material for the wing fairings, or so I thought, however having cut some and tried to bend it to follow the rib outline I found it to be too stiff, it’s also quite difficult to sand without galling. Instead, the eurothane core recovered from Recticel flooring insulation (same as the cowl plug) was used. This cuts, bends and sands easily while still being light. All but the curve around the leading edge was formed from the eurothane, the front part was completed with lightweight fairing compound mixed with fibreglass resin. Once cured this can be sanded but it’s quite a hard material, it’s easy to sand away the softer adjacent balsa so care must be taken. The first intention was to apply filler to the surface of the eurothane and sand down to feather edges but rejected that idea given how hard the cured filler is, compared to balsa. Instead, the fairing was covered in 2 layers of 50 gm glass cloth, one layer just covering the fairing and a wider piece overlapping onto the fuselage and wing. This provides a resilient surface on the fairing and allowed for easier blending at the edges. As the fuselage is to be covered in Ceconite and the wing centre section in glass cloth, I wondered how best to achieve a neat join between the dissimilar materials. A flash of inspiration was to mould fairings on top of the existing fairings. By being removeable, at least initially, the Ceconite/glass cloth join could be hidden under the top fairing and, being fitted after painting, would definitely look like a removeable item. Cutting the moulding into 3 sections (the same as the fullsize) and adding some small screws at about a scale 6” pitch, glued into pre-drilled holes will hopefully complete the illusion. Here, the area to be moulded is masked off with release wax being applied - 6 coats, buffing in between, usually does the trick. 2 layers of 80 gm cloth made the fairing, it seems to be of adequate rigidity so not worth adding more layers when the other side is done. The fairing weighs 10 gm, it now needs a further coat of resin to fill the weave then it can be rubbed down with wet & dry paper and trimmed to final size, the black outline. Given how easy this was to do, I’m motivated to do something similar for the wide straps which cover the wing fold.
-
Thank you for the compliment Stuart. I use epoxy resins for everything, buying from Bucks Composites usually as Graham Buckingham trades at shows and provides prompt and helpful service when ordering online. His Formula 50 or L285 will cure in 24 hours at room temperature (20C), though probably best to leave for a couple of days before cutting back to a smooth finish with wet & dry cloth. Stored in a dry, warm place part-used bottles or cans seem to have an indefinite shelf life. I try to be careful with measuring so that not much is wasted and really don't find it an excessive expense, particularly in the overall scheme of how much a model costs to make!
-
It was fortunate that Brian Taylor produced a plan for the Gull 4, I've not been so lucky. I have a book which describes the evolution of the Gull series including the widening, stretching and enlarging of the areas and control surfaces from Gull 4 to Proctor although there are no meaningful drawings. With the fuselage inverted in its cradle the wing centre section could be placed in position and checked for alignment before the dreaded no-going-back-from-here operation of gluing. After allowing the glue to dry overnight a milestone was reached with the model being able to sit on its wheels unaided. The next jobs are to blend in the line from the bottom of the cowl to the main spar and also make the wing fillets. Completing the footholds has had to be delayed until some gelcoat activator arrives.
-
Thanks for the compliments, unfortunately for this project I haven't been able to find any reliable drawings, most of the design has come from photographs - an inherently unreliable method as the pictures are rarely taken at right angles to the subject, so I doubt it would pass muster in a scale comp. Thanks also Richard for the tip about fairing compound, I'll probably use that over the top of blue foam which will form the bulk of the fairing. A trial fit of the 'test' foothold. This would definitely not pass muster as I'm sure the floor should be level with the ground, but I couldn't get it to fit any deeper as the inner flap was in the way. For the one further forward there is nothing in the way but installing one foothold level and one at an angle may look a bit silly so it may be best to keep the same (incorrect) angle.....I said earlier its a sports model!
-
Thanks for the photos Richard, its heartening to know that you’re taking an interest in my amateurish efforts. Construction has reached the stage where the wing centre section and fuselage need to be mated, but before that can be done the radius of the fairing needs working out as the edge of the fairing will determine how far the footholds are from the fuselage. I’ve given myself some problems here as the footholds need to be installed in the 1/8” wing sheeting before the wing and fuselage can be glued together. The fuselage is going to be stuck directly onto the wing sheeting so the centre section sheeting needs to all be in place first. After studying quite a few photos which include the ones you’ve sent and the ones of Beryl Markham and Jean Batten’s feet (!) and measuring my wife’s more sensible shoes, I’ve concluded that the footholds would have been about 8.5”x 5”. As best I can judge, it looks as if the radius of the fairing ellipse was 5”. These dimensions could well be wrong of course but provided they are not grossly out of proportion, it will be good enough for what is essentially a sport model. When designing the Vega Gull I gave scant attention to the wing fairings and now find I didn’t build in the support for the fairings on the fuselage sides, extra balsa has now been added to provide a fixing and to allow for blending in. The fairings look as if they were attached after covering and possibly removeable so I’ll try and incorporate a step at the edges with masked primer. The next consideration was how to make the footholds, and mount them, with the least weight gain. The options were to laminate a few layers of 1/64” ply around a former and them glue on a base, or wrap litho around a base. I decided in the end to try making them out of fibreglass, the benefits being that if moulded there would be nothing to come apart later, minimal weight and all four would be identical. A plug was shaped (intentionally made too long and too high so that the subsequent casts could be trimmed later on) and covered in two layers of 80gm cloth, then once dry, a further coat of resin was applied to fill the weave and finally rubbed down to a smooth finish after leaving to harden for a couple of days. Two layers of 19gm and one of 50gm cloth produced a result which weighs 4 gm. I’ll call this one a test piece as the inside corner is a bit rough (needs some gelcoat adding before glassing I think). The result is encouraging though so will persevere with moulding the footholds in fibreglass.
-
Percival’s designers added a bit of flair when it came to The Vega Gull’s carb air intake, it’s a long, streamlined affair extending to one third the length of the cowl. It was fairly easy to make so couldn’t be omitted on the model. A plug was made from scrap B&Q plywood, sanded to an acceptable shape, and covered in one layer of 100 gm fibreglass cloth. Following 6 coats of release wax, the intake was formed with 3 layers of 100 gm cloth and left to harden overnight. The next morning the moulding was given a further coat of resin to fill the weave and then left for two days to cure sufficiently for sanding. The intake would be an awkward thing to hold while rubbing down but the plug makes the prefect grip so rubbing down to a finish was achieved prior to releasing. The plug had been made longer than needed and with deeper sides than the finished intake so that it could be cut down to the correct dimensions (which were an estimate anyway but shown against a photo of a remaining Vega Gull for comparison) and to form lugs which would slot into the cowl and provide a substantial fixing. A tungsten carbide disc is ideal for cutting fibreglass, anything else is quickly blunted. There is a double row of hinges on either side of the cowl. Presumably this is so that the hinged portions could be folded right back without straining the hinges. The hinges were replicated by marking out and cutting slots (1/2” pitch) on both long edges of a strip of litho. This was the second attempt, I had made a pair with 3/8" pitch as I guessed that the real thing would have been 1 1/2" pitch, however on a recent visit to Old Warden I got the chance to measure their Hawk Speed Six cowl hinges and found they were 2" pitch....the others are now in the bin. The strip was then held in position by a straightedge and each tab lifted through 900 before pressing and rolling back down again with a length of 1mm piano wire underneath. Before attaching the hinges the panel lines were added using fine tape followed by a few coats of epoxy primer to build the depth. The cowl panel line also set the limit for the hinges Once dry,the primer was cut back with wet & dry until the colour of the tape was visible and then peeled off. The simulated hinges were glued into place with contact adhesive and then given a couple of coats of primer to seal against any subsequent fuel or exhaust ingress. The coats of primer tended to fill in the previously cut slots so these were carefully scratched across with a knife to try and make the gaps more prominent. Before gluing on the carb air intake the area was sprayed with the finish colour as it would have been impossible to reach later and would have left an unsightly white bit. As there was some paint left in the gun, it seemed a shame for it to go to waste so couldn’t resist the opportunity of seeing what the finish will look like……..turquoise is a bit garish but who am I to comment on the taste of a Percival customer of 1936. On my screen this looks like light blue, but its even more garish in daylight!
-
Steve, the lowest part of the ribs do not have to touch the board while building. If you pack each lower spar using something like 1/4" balsa, it will be fine. Just make sure that the spars seat fully into each rib as you go along - a straight edge dropped into the top spar slots will help here.
-
Thanks chaps for the encouragement. Having paid a brief but enjoyable visit to the Best of British event this year and seen the way its being run, I would like to go to the next one, probably with the caravan in tow, so that prospect is a further incentive to make progress. Richard, I like the foot-hold flanges you’ve made and will attempt the same trick of using a cutting machine. I’ve only cut paint masks before and not considered cutting plasticard, you’ve obviously had success with these thicker materials. Did you use the same (standard) cutter blade? The intake flange on the cowl was made using litho, which worked ok though is probably a bit too wide, using a cutting machine means that small items not easily gripped by hand could be produced more accurately. Looking at pictures on your RCSB site which include the foot-holds and then measuring a shoe, I make the presumption that they would have been about 12” x 6” therefore 3” x 1½” at ¼ scale, did you come to a similar conclusion?
-
With the shortening and cooling days, residence in the workshop is becoming more appealing and with it a view to continuing with the Vega Gull. Spring and summer were not entirely neglected on the modelling front as an SE5 repair/restoration project was completed and the model subsequently sold. Also, a 20 year old Chrislea Super Ace which was looking rather decrepit has been recovered and painted, hopefully it will fly more frequently next year. Some thought over the last few months has been spent on the shelved Vega Gull and what to do with the wing retention. So far I’ve rejected the options for having a scale wing fold given my limited workshop facilities and will probably simply use the existing lugs (in their present position) to attach the wings. To prevent this project from being a disappointment and permanently shelved, I thought that if I progressed parts other than the wings I’d get myself into a psychological position where all the other difficult and time consuming bits had been done, therefore it would be daft to shelve the project with so little else to do! With the building board cleared the Vega Gull was resurrected, with the first task being to get the other door made and both doors hinged. The method adopted for the first door worked, so why change things for the second. Suitable scrap wood was fashioned into a template for the inside of the doorway and then six layers of 0.9mm (1/64”) ply were laminated to form the shape. The hinging was from cut-down strip hinges that had been squirrelled away years ago waiting for a suitable use. The hinges are 2.4mm thick so a recess was needed in both the door and jamb or an ugly gap would have resulted. The next problem then was how to cut the rebate leaving a nice straight and flat surface for the strip hinge. The layers of ply, once laminated, form quite a hard material which I doubt could be reduced evenly without using some mechanical assistance. The solution was to make a straight edge (two actually) from flat bar, clamp them in turn to the door and jamb, sanding down with a rotary file. The method worked quite well. The next task was to latch the doors. With them being such an unusual shape, they really needed latching at both top and bottom corners. Small neodym magnets offered an unobtrusive, lightweight way of holding the doors in just the right position. Not wanting to drill into the corners and weaken them, small fillets were added, which wouldn’t be seen when the doors were closed. A feature of the Vega Gull, though not exclusive to it, is balance springs for the doors. At rest the tail sits down which makes the doors hard to push and keep open, so designed in is a cable attached to the outside of each door which attaches to a spring under the cowl. It was a fairly simple job to replicate and added minimum weight. If anyone is wondering....the incomplete instrument panel is only temporarily installed for effect, its also held in place by neodym magnets so is easy to extract. The doors have been progressed enough for now, the glazing and the chromed glazing bars will be fitted once the model is covered. The next job is getting some detail onto the cowl and then attention can return to the wings.
-
Ron, Sorry to hear that. If a valve has collided with the piston, are you sure its not bent the valve or pushrod? If you've still got compression when turning it over, I would think its ok. If all that's happened is a dent in the piston, you're a very lucky chap!
-
I’d like to add my thanks to Ron Gray for organising the gathering of Laser powered aircraft – and anything else with a British connection. A couple of proving flights with the Chrislea Super Ace were enjoyed following its refurbishment; I also enjoyed meeting and chatting to some familiar stalwarts of the modelling fraternity. This was my first visit to Buckminster and have to say I was impressed by the field and facilities, hopefully I’ll be allowed back another time.
-
Oops - well spotted! Yes, 20 degrees.
-
The first task will be to make sure the cowl is scrupulously clean, no silicon remaining from the original mould (unlikely on the inside) and no oil or grease (much more likely given it’s a used cowl). Wash the cowl in soapy water and then when dry, go over the thing and particularly the area you wish to cover, with a chemical degreaser (panel wipe). 100 gm cloth or thereabout will be easy to apply and adapt to the shape. Two or three layers may be needed depending on how flimsy it is. The good thing about fibre-glassing is you can tailor the amount needed to specific, ie very flimsy, areas. Brush a coat of epoxy onto the inside of the cowl and then after laying the cloth, wet-out the cloth by brushing more epoxy if needed. Add the second or third layer as you see fit, without seeing the job its impossible to gauge how many layers will be required though I doubt if you’ll need any more than three. Yesterday I moulded a wheel spat using three layers of 100 gm cloth and its more than adequate, weight up the front though is usually of little consequence. Keep the ambient temperature to around 200C, you’ll get extended curing times with lower temperatures. That’s all there is to it, epoxy resin is safe and equipment used can be cleaned with standard thinners.
-
Question About Differential Ailerons
John Rickett 102 replied to Nigel Heather's topic in All Things Model Flying
Nigel, I don't know what the manufacturer's intentions were, though it looks as if the aileron horns couldn't be positioned any further forward due to the chamfer. It would have helped if they had fitted horns which were raked forward so that the holes were directly under the hinge line. You may be able to find some and fit them yourself. Failing that, if you move the servo horn to be 30- 45 degrees, instead of the 15 degrees or so it is now, it will give you the more-up-than-down movement you're seeking, you'd just need some longer pushrods, which you can bend to the desired length. -
Question About Differential Ailerons
John Rickett 102 replied to Nigel Heather's topic in All Things Model Flying
There's your answer, the aileron horn is set further back from the hinge line than the servo arm is in front of the servo pivot. You would need to add more servo differential, easily done with replacing the push rods with slightly longer ones. -
That's fine Allan, good luck with your new radio. I was merely answering your query as to whether the later Futaba transmitters have the facility to use Throttle Cut on more than one channel. It took me a while to figure it out but once I discovered that separate 'conditions' could be created (up to 8 in the case of the 16sz) for each model memory a whole new world of possibilities opened up! I'm sure other brands have similar faciilties though probably called something else. I found it useful on a 4 engined model with all engines operating on a single throttle stick. If an outer engine cuts, flicking a switch to activate Condition 2 brings both outers to idle, its saved the day on a couple of occasions now.
-
I used Futaba for the first 25 years or so of my flying career, but changed to FrSky Taranis when I found that my 10C couldn't give me a throttle-cut that would operate on two separate throttle channels. Are more-modern Futabas more flexible now? Allan, Yes, using 'Conditions' will allow you to set up as many channels as you want to operate in the Throttle Cut mode, or just about anything else you want to do when a particular switch, stick or slider is moved.
-
Presumably you are using fresh E5 petrol? A flush of the carb with an aerosol carb cleaner won't do it any harm.
-
What covering to use depends largely on what type of finish you want and how you intend to fly the model. Unless you’ve substituted the balsa wing dihedral braces for ply ones on the Southerner Major, then a (doped) fabric will offer increased strength especially if you cover the underside of the wing in one piece…to help prevent the wing folding if engaging in exuberant aerobatics! The original Southerner was intended for gentle free-flight not high G turns and loops which a radio controlled version equipped with a relatively powerful engine, such as a Laser 75, could perform. Uncovered, its quite a flimsy wing so I’d suggest using a covering which adds stiffness. I’ve been carrying out some experiments using China Silk, it’s a cheap polyester which will heat-shrink and comes in many standard colours, so if you are happy with stock colours and want to save on the time, expense and weight of a painted finish, you may consider this type of fabric, though it still needs a method of adhering the fabric and then doping. The picture below is a test piece with added simulated rib stitching to see what it looked like. Leaving aside the rib stitching the covering seems as tough as Solartex or Koverall (both now out of production) so would be a viable material if you are happy with basic colours. This test piece is 9" square, covered and doped both sides, and weighs 1oz. I built an electric powered Southerner Major and finished it in high gloss 2K car paint – completely over the top but it was an experiment in spraying this type of paint in preparation for a Shoestring under construction at the time. I was pleased with the result but it added weight which of course a coloured fabric wouldn’t. I consequently had to add lead to the nose. I also equipped it with glassed spats (with brass fittings) and a tailwheel which also contributed to the weight. Ready to go but without battery the model weighs 7lbs. The wing can carry the weight but its faster than I would like for a vintage model. The choice you have is what type of finish you want and how you intend to fly the model. I'd presume that with fitting a Laser 75 you want a spirited performance, which will be best served with a fabric covering. It would probably stooge around on a Saito 40, in which case choose a film covering.
-
Laser engines - the state of play following their closure
John Rickett 102 replied to Ron Gray's topic in IC Engines
I checked this morning that my inline 200 had been received. Geoff confirmed that they have it and that Jon should do the work on Friday....so far so good. -
Laser engines - the state of play following their closure
John Rickett 102 replied to Ron Gray's topic in IC Engines
Ok Steve, Thanks, I've now spoken to Geoff and he's confirmed that the engine should be returned straightaway and he will carry out the modification.