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John Rickett 102

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Everything posted by John Rickett 102

  1. 63,000 cubic meters used in Heidrun, Frank. Much of it poured using wheel barrows!
  2. Looking good Steve, If you dampen the top side of the sheet just before gluing, it will adopt a curve and put less stress into the framework below.
  3. Steve, On a model like this, I'd advise to use a 'proper' hinge, not tape or mylar. I assume you will be covering the model and painting it rather than covering in film. If that's the case then its best to be able to separate the hinges for covering and painting, and for any subsequent work should it be necessary in the future. Small hinges which are glued in but with removable pins are are available through the modelling outlets, the one in the middle is a Kavan hinge (widely distributed), or you could use brass doll's house hinges which would need some hardwood, or ply, inserting to accept the screws. Here are some examples. Three or four per surface would suffice for your model and could equally be used on the rudder and elevators. If you use the removable pin type and you feel so inclined, the pins could be substituted by a length of wire which goes through all the hinges, this method is sometimes easier if you need to constantly remove a control surface - remove a rudder for transport, for example.
  4. The recent wet weather provided a justifiable excuse for some workshop therapy. The radiator shutters were always going to be the most difficult part to create, especially in making them appear to be continuous when in fact there is one part in the fuselage and one in the cowl. With a new blade in the band saw and by using the width guide, some strips of ply were cut for the sides of the shutters themselves. The mitre gauge was set to 15 degrees and then slots were cut half way across. By moving the width guide so it almost touched the blade, the slots for the shutters were cut and hey presto, a radiator shutter kit produced. A simple jig was made out of whatever soft wood was lying around to hold square each assembled piece while the glue dried. These are just pushed into position to check the result, they can’t be glued in until the background has been painted and the mesh inserted behind.
  5. The cowl will be wrapped in 1/64" ply so to improve the gluing area, scrap 1/8" balsa has been added to the formers. The front, which forms the radiator header, has been built up with ½" balsa prior to sanding to a curved shape. The fuselage front has been cleaned up and distance pieces added in readiness for the radiator shutters to go in. A piece of 1/64" ply forms the very front of the fuselage in between the radiator shutters and also forms the lower part of the cooling air inlet for the Laser V. The original cowl was located by a 1/4" dowel in each corner. This arrangement will be used again, the actual retention relying on neodym magnets. When the model was first built, I'd used a Terry clip to retain the cowl, but little, powerful magnets seem a more elegant solution.
  6. Mike, It was my fault. I had earlier changed the bearings (fitted stainless ones) and all was well for a number of flights. It seems that I didn't tighten the bolts sufficiently, neither did I use Locktite, which I'm advised not to do, eventually the housing came loose and departed. The sound that something was amiss only lasted a few seconds. Of course this happened in the air and not while running up. It will be an expensive and time consuming mistake to rectify but we'll get there.
  7. A gyro isn't compulsory, or even necessary with competent pilots, but with my slow reactions it helps to stabilise the wings in windy weather and add a sense of realism.
  8. They certainly fly well, one of DB’s finest designs in my opinion, simple scale but an unmistakeable shape. I’ve often mused about building another one with the centre sections fixed, which would mean the undercarriage wouldn’t need removing for transport and with the outer bays remaining in their rigged position. The inboard sections would require temporary distance pieces while derigged, Duncan Hutson did something along those lines with his Tiger Moth kit, which seemed to work.………so many aeroplanes that could be built and so little time………
  9. I thought I’d have a rest for a while from the latest project and get some outstanding jobs done on previously completed models requiring some TLC. As this is a DB SE5 thread that has gone quiet, I thought it would be a suitable place for some refurbishment coverage. Last summer, and a first for me, I had the misfortune to have the bearing housing of a Laser 200v part company with the crankcase. During the process the cowl was knocked off, the model landed without further damage. The housing, complete with prop, was found in the wheat field straight away by an eagle-eyed club member – how’s that for luck, but the cowl wasn’t found for a week and in the meantime had suffered being chewed up a bit by a harvester. Slightly disappointing as the model had been recovered and painted only eighteen months before. Too much damage had been done to repair so a new cowl needed making, though it’s taken me until now to get round to it. The original plan for the model has long been lost but it was a quick job to measure the fuselage and come up with the basic formers. The original cowl is simply 4 pieces of 1/8” ply, a few strips of ½ x ¼ and ¼ x ¼ balsa, covered by one piece of 1/64 ply. That’s the simple bit, the more complicated part is forming some radiator shutters and a decent inlet path for cooling the vee engine. However, it’s all doable and, once the engine has had the magic wand of Jon Harper passed over it, will be flyable again. The pressing need is to make more storage room if the master plan of aircraft to be built is to be continued. The short term plan is to sell the SE5. As a model it’s a joy to fly but because of the rigging, it either takes a while to prepare at the field, or if left rigged, precludes taking anything else and takes up even more room in the shed. Either way it’s got to find a new home this year but I doubt anyone would want it with a damaged front end. The damaged cowl caused by the fleeing bearing housing. Damage to the fuselage was confined to the radiator shutters A few hours work and the new cowl is taking shape The easy bit done, now onto building up the front end. The exhaust manifolds can be reused This rocker cover survived, the other was in a mess The rockers were moulded ABS, as a spare part from DB they are £18 - I think some simple ones made from glass cloth shouldn't be too difficult. Similarly there is a radiator kit at £45 but I'll remake the shutters the same way as shown above. I've still got the rest of the packet of mesh I can lay my hands on - life is not all bad! Hopefully we will get back to something like this.
  10. If you change the incidence the model will adopt a different 'sit' in the air to achieve the correct angle of attack for the flying speed - decrease incidence and the model will sit tail down. With the wing being quite a bit higher than the thrust line on this design there is a strong drag/thrust couple ie, an up pitch tendency due to the drag of the wing. Mr Boddington knew what he was doing!
  11. Steve, I'd advise building the wing as it was designed by David Boddington. A flat wing will not only look less pretty it will have no lateral stability. It simply won't fly as nicely, tending to wallow all the time and needing constant aileron (and rudder) correction. When completed, If the cg is a bit forward, it will add to pitch stability which will help with the easy flying characteristics, you may just need a little more 'up' elevator range. Looking forward to seeing this one.......
  12. Well done Steve. Excellent choice, you're thinking along the right lines!
  13. Thanks for the commiserations and good suggestions, repositioning the lower hinge pivot more to the rear would probably be the least amount of work. I think I could experiment with the left wing as little has been fixed which cannot be easily cut away. It would need some 2mm flat bar about 25mm wide, if anyone knows of a source? If it works for the left side I'd be a bit more confident about cutting into the right. The folding flap section may have to be relieved at the top and bottom to make space for a repositioned hinge but it’s hardly a stressed area, spruce was used only to allow the hinges to have a decent anchor, so would be simple to modify. The top hinge would need remaking and angled back to allow the M3 bolt to line up on all the holes. The hinges are only 2mm mild steel so will withstand a small amount of twist which will be easier than making the wood supports with an angle which accommodates both the dihedral and the offset we are now talking about. The first idea was to move the top hinge forward, but moving the lower one back is a better suggestion. This is the view from the underside of the centre section, right hand side. I really don't want to straighten the centre section ribs as I'm sure it would end up weaker. The undercarriage mounts are right at the edge and the holes were awkward to get right, plus the leading edge is now in the way. After the last few days of deliberation, I’m now a little less circumspect and hope that the original plan of practical folding wings can be achieved. The model was always going to be sport scale, my building skills aren’t to competition standard, so these modifications won’t potentially lose any scale points. Schoolboy trigonometry will have to be brushed up to calculate the amount of offset which will put the wing tip just under the tailplane. As there is the existing dihedral which was the original culprit, I don't think its a simple calculation, but a bit of experimentation without spoiling what is already there will probably yeild a result. Interestingly, the picture below shows the Proctor wing fold attachments (this one awaiting restoration at East Kirkby) and there doesn’t appear to be an offset in the rear mounts, perhaps there doesn’t need to be if the end rib is perpendicular – my fundamental mistake I think. The Proctor was the military successor of the Vega Gull and apparently retained the same wing fold.
  14. The left wing was progressed sufficiently to allow sorting out the hinges and making sure the dihedral was the same as the right wing. I was quite pleased with the result so thought I’d drop the fuselage over the centre section to see what it all looked like. At this point I realised I’d made a catastrophic error, the geometry of the wing fold is completely wrong meaning that when the wings retract, they follow a descending arc and end up below the level of the tail wheel by a considerable margin! The reason is that the dihedral was incorporated into the centre section ribs not the outer panels, I did this to maximise the available thickness of the wing which occurs in the centre section and reduces progressively toward the tips. I didn’t think at the time that having the hinge axis at the dihedral angle would have any effect on the wing fold, but of course it means that the retraction plane is angled……..in the wrong direction. Having played with making up some more hinges to move the hinge axis in the opposite direction, which works to some extent, I’ve concluded that the gap between the centre section and the wing would be too great. It would be major surgery to cut out the hinge supports, straighten up the centre section outer ribs and start again, as well as adding weight, so I’ll just have to live with the situation. Here the wing is now higher than the tail wheel but there would be a large gap to fill between the centre section and wing which would also put the trailing edge out of alignment. Its not the end of the project, the wings will still fold for transport if a tail support is made to keep the tail off the ground sufficiently, but with the wings stowed it looks a bit silly and defeats the original intent of a practical model with folding wings. This model may now be put on the back burner until enthusiasm is rekindled.
  15. I deliberated for a while on how to retain the folding sections in their flying position. I wanted a quick method of releasing them (as in when it starts raining and the model has to be packed away smartly) and decided that spring loaded latches would be a secure and positive method. This method was used on the Leopard Moth and has given good service. On that model the pins were home-made but I found these brass and steel ones were still available so thought it would save a bit of time - not to scale of course but shouldn’t be obtrusive once painting is complete. The latches were epoxied into ply supports, including 1/32" ply rib doublers, and set into the folding section as close to the trailing edges as possible – actually quite a distance from the trailing edges as the flaps and ailerons each get in the way. I'm (fairly) confident the latches will hold ok, it all seems rigid enough on the bench - it will be disastrous if one lets go in the air! The ailerons were progressed at the same time as the folding sections; they form an integral unit and the trailing edges have to align. After slotting the ribs for additional spars which would become the corners of the ailerons, the hinge recesses were formed with a small sanding block the same width as a hinge and then the aileron was cut free from the wing and faced with 1/16" sheet. There's not much to an aileron, here capping strips have been added. A decision was taken to install Hitec 5245’s for the ailerons and well as the flaps, they pack quite a punch for such small units. A few years ago Futaba S148’s would have been the standard servo for ailerons, yet only had a torque of 3.0 kg.cm whereas these little units provide 5.5 kg.cm (at 6v), so with nearly twice the torque available there seemed no reason to fit larger and heavier servos. When first studying photos of the real thing, it wasn’t obvious why the shroud for the wing fold gap was kinked. In trying to incorporate a folding wing on the model the penny dropped, the wing join has to be staggered to allow for that part of the structure which is behind the pivot point. I won’t attempt a shroud, just make sure that the gaps have been closed as much as possible. Folding section just about complete, showing access to the servo. A 1/8" balsa cover will be made which will be glass cloth covered to add strength and stiffness. The wing as near complete as possible but without sheeting. Once the other wing is made, there may have to be some adjustments so don't want to cover up anything which there may be a need to access later. A start now needs to be made on the left wing, hopefully it will be straightforward but probably not as satisfying as progressing the first one.
  16. While the section was accessible prior to sheeting, the servo supports were installed. The servo plate is 1/8” birch ply with a couple more strips where the holes are drilled to provide a bit more support with negligible weight penalty. The servo plate slides into position along spruce rails and is then retained by the cover. All this puts to good use the scrap bits that have been collecting in a drawer. The servo is a Hitec HS 5245MG, 4 in total for the flaps. Programmable, digital servos are possibly in excess of what’s needed here as with modern transmitters being able to reverse the output, adjust speed, fail-safe and throw, the programmable part of the servo amp is redundant but with metal gears and a torque of 5.5 kg.cm at 6v, this little unit fits in easily and will certainly do the job. The flap is simply a triangular box made from 1/16” sheet. A length of ½ x ¼” provides initial stiffening and support for the hinges. Recesses for the hinges were chiselled out prior to gluing into position. The ribs were then glued in with a few extra, scrap ¼” sheet ones as a horn support. Kavan hinges will be adequate for this job and have the benefit of the pins being removable, should separation of the parts be required later on. With the trailing edge of the wing getting quite thin, there is not a lot of depth for all the sheeted bits. The ‘roof’ of the flap bay was cut from 1/64” ply with a strip of ¼” square balsa added to help keep straight the otherwise unsupported front edge. The folding section taking shape. Underside of folding section showing the flap resting in position. Flap installed and connected to the servo, ready for sheeting.
  17. The right hand wing hinges have now been lined up, drilled, the dihedral set and all permanently screwed into position. Besides the main spar webbing (1/8" balsa), webbing has also been put in at the roots where I imagine the highest stresses will be. Some 1/8" balsa, 3/8" wide has been added to the first two (liteply) ribs to provide a better gluing area for the sheeting. The wing folds as it should but at this point I've no idea whether the other one will be level with it at the tips, so perhaps shouldn't get too carried away with the sheeting and making the screws unreachable. The leading edge will be sheeted to form a D box as well as the first bay of the outer panel. This won't be scale as there doesn't appear to be any sheeting in this area on the real thing, but practical is sometimes better than sticking tightly to scale in my opinion. The distance between the upper and lower hinges is 55mm, I was concerned that there could be some flexing with the wing hung off this arrangement, but am relieved with the rigidity, even without the sheeting. A start has been made on the folding section, this also carries a split flap and will house the servo. 1/2" x 1/4" spruce strips will carry dolls house brass hinges to enable the section to fold right over onto the wing.
  18. Ok, I can see the build thread, thanks. Laser's website has been up and running again for some time now, you could trying accessing it here
  19. Richard, Perhaps its early days to be concerned about engine substitution, although keeping the options open during a build is a wise precaution. The smallest Valach is 60cc, so could possibly be in excess of the requirements for a Gull 4, which I doubt had a sparkling performance fitted with a Gipsy Major 1 in the 1930s. Kolm produce a 50cc single, I’ve got one in a 1/3 scale Leopard Moth which weighs 34lb, the power seems about right. The engine is one of the early ones and for some reason is now on its third set of front bearings in just under 200 flights. Kolm are now up to Version 4 of the engine so I imagine they've found the need to introduce some improvements along the way. Apart from the bearings in my example, its a nice engine. Machined from solid it’s a slim design with the inlets and outlets at the rear in the same manner as a Laser. Its also shorter than a Laser 200i so may need less butchery to install. I’m very interested to see how you get on with completing the Gull 4, you need to start a thread on this forum………
  20. It’s good to see that another example of Edgar Percival’s talents is underway and that Arthur Searl’s creations live on. There seems to be so few Percival designs flying - the Mew Gull has been kitted before and available as a plan, but little else I can think of, what have modellers got against them! The Vega Gull was a bit larger than the Gull 4, so at 1:3.7 scale the wingspans will be much the same at 117 - 118”. I’d expect a Laser 180 single and a 200 twin to have similar power outputs, so if the Gull 4 gets to be airborne first, it will be interesting to learn if (power wise) it was a good choice of engine. This will be the third model I’ve built with folding wings, though the first cantilever wing. I’ve found it’s a speedier job to pack a model back into the van, or awning, when the heavens open than the alternatives of tubes or bolts. I accept they are more complicated to build and with all the fittings and screws required, the final weight tends to be greater. I’m optimistically hoping for a weight of 25lb. I have a much flown Chrislea Ace weighing 25lb and powered by a Laser 180. The power is……adequate, but it is quite draggy. Percival designs were more streamlined so a small increase over 25lb should still be ok. Thanks for the tip about using black foam as a method of directing cooling air to where its required. I’ll see how the motor performs before adding more baffles but hadn’t considered a material as simple as foam glued into position - something to remember.
  21. Thanks Ron, All's getting better by the day so in these dark months hopefully some meaningful progress will be made. It's just as well as Beryl is getting impatient to be airborne!
  22. A tumble off a pushbike led to an enforced building board sabbatical. Well on the mend now though so what better physio for a poorly hand could there be than making a slight deviation from the planned order of things and starting on a wing panel. LMA Member Bob Maltby had made an excellent job of cutting the ribs from a design drawn up in Compufoil 3D. Not having learned anything about CAD design, I find Compufoil a simple way of achieving the same thing when it comes to plotting and lofting a wing. The picture shows the earliest stage of discerning that the few bits of wood are actually forming a wing. The large gap is where the ribs have to been cut off to allow for the wing fold supports to be added. Its crucially important the hinges are positioned in the right place as three things are determined by their position: · the dihedral (50) is properly set · the wing folds without pinching · the relative heights of each panel are correct The centre section is being sheeted in 1/8” balsa with the outer sections in 3/32” so this adds a bit of a complication to what is already a hit and miss affair. I think that much playing with thin plywood shims will get the correct heights but there can be only one attempt at drilling the spruce/plywood spars. To overcome making a mess of it. the plan is to devise a method of holding the ¼” ply pieces in position without gluing so that if mistakes are made a new piece of ply can be substituted without having to cut out the previous piece. At least progress is being achieved once again after a 4 week delay, I’ll just have to live an extra month to make up for it.
  23. Found them Frank, thanks....Molex. It makes 4Max prices quite competitive given that smaller quantities of pins can be bought for only a small proportional increase in price. I think that's the way to go. Thanks for the assistance.
  24. Excellent news Peter, thankyou. I had heard that Phil Clark of Fighteraces had taken over the supply of Ashlocks but couldn't see them on his website, so good to know they are still available through 4Max.
  25. Thanks for the further suggestions. Yes, they probably came from Ashtec, I've still got some of their Ashlock connectors. It a shame the coloured connectors are no longer available, they were such a simple idea, I'll have to resort to one of the other methods. Thanks for the help.
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