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David Hayward.

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Everything posted by David Hayward.

  1. Well with construction pretty much complete its time to check the CG. Instructions advise this should be 6” back from the mid-point leading edge, so with that marked on the wing and some card providing protection to the veneer – image 36. Model inverted and placed on CG stand; it balanced about 3mm in front of the marked position, so by the time its covered it will probably be spot on. Very happy I went for the OS 91 as the SC 120 was about 12oz heavier and would have meant weight in the tail to balance – image 37. And model now ready for covering and decoration – image 38.
  2. Yes I feel a 91 will be fine for me and having done a preliminary check on balance with the 91, the extra weight of the 120 (almost 12oz heavier) would have made it more difficult to get the CG as specified.
  3. After much deliberation I have decided to go for a 91 size engine despite having an SC 120 FS looking for a home. I think a 91 will have ample power for this model combined with my very moderate skill level. I found an OS 91FS Surpass on ebay for a good price, which I have now had a chance to check over and run up in my test stand; all seems fine. Time to get it in the model. Now the only detail I have for positioning the engine is actually the engine cowl, nothing in the instructions and no plan to refer to, however, the cowl has a mould line running horizontally around its perimeter. This line locates the vertical height of the engine on the firewall, so nothing more required really – image 33. Instructions recommend 2-3 degrees of side thrust and 1 degree of down thrust. I opted for 2.5 degrees side thrust and 1 degree of down thrust. In order to calculate the necessary spacing to achieve the required side & down thrust plus the offset to ensure the crankshaft exits at the centre of the cowl I have produced an Excel ‘tool’ that calculates this for me. A link here to download a copy should this be of interest; note it works best on a PC or laptop, not so good on tablet or phone. https://www.cadmac.co.uk/index_htm_files/Engine%20Mount%20Spacing%20and%20Offset%20Calculator%20-%20Final-v2.xlsx Image 34 shows the engine mount in place, plus blocks fitted for engine cowl fixings; top fixing for cowl actually goes into the engine mount. With the engine in place I then set about cutting holes in the fairing with careful measurement to hopefully ensure they came out in the right places – image 35.
  4. With reference to image 32 the pushrod guide tubes on each side just about exit through the fuselage side, providing enough surface for the covering to stick. When covering I will cut a small slit in the material at the point where the rod exits and slide it into position. Same technique for the rudder closed loop tubes. Hope this helps.
  5. Wing tips don’t normally cause me any problems but the kit was supplied with two pretty chunky wing tips which were not long enough to span the chord of the wing and aileron – image 28-b. Making another pair of wing tips a suitable length would not be a problem, but I wondered if I was missing something, so spoke with David at Balsa Cabin, who was a little confused himself to begin with, but concluded that the wing tips were not required. The Smooth Operator is based on a CAP 222 which does not have wing tips as such, the wing and aileron just finish flush at the end. Having said all of that I felt I wanted to provide some degree of protection to the ends of the wings and ailerons, which are quite vulnerable being just veneered foam, so added 15mm wide end caps – image 28. At this point I randomly decided it was time to fit the canopy which fits the preformed shape of the front and rear decks very nicely – image 30. Next up was fitting three servo’s across the fuselage on supplied ply rails and mounting switch onto a piece of lite ply. I fitted 2mm piano wire pushrods to each elevator supported through sections of snake outer at two points along the fuselage and smaller diameter tubes at the point where the rods exit the fuselage. Rudder closed loop system also installed at this time – images 31,32. The open structure of the fuselage certainly made this all very easy to do.
  6. I have a hangar one kits Calypso on the bench which you can probably see in some shots, which is waiting to be covered but I think I'll finish the S.O now I've got into it.
  7. Yes they are, if you look back at image 20, you will see as supplied the servo cutout is oval, so just requires cutting square and fitting balsa to form the box.
  8. With the wing panels joined and centre section glassed, then set about gluing the fuselage under section to the underside of the wings ensuring all square. Once dry, detached from the fuselage and now have wings with underside of fuselage attached which locates and holds wings in position, very neat design. Tailplane is also now located and glued into it’s pre-cut slot, just a little bit of work to very slightly open out the enclosure and level the tailplane with the wings.
  9. A few little bits and pieces, but its all progress, tailplane halves butt jointed and glassed over the join. Before joining the two wing panels I made up the servo boxes in each and fitted the control horn mountings into the ailerons. Wing panels came ready to join with correct angle at the root, so packed up at the centre by the specified 6.5mm, added epoxy, weighted and clamped; centre section will be glassed once dry.
  10. Fin side blocks added and preparation of flying surfaces gluing balsa leading and trailing edges to wings and tailplane.
  11. Thank you for the suggestion, I have considered a 90, but I do have an SC 120 looking for a home, so will probably go with this and save the expense of buying another engine.
  12. Thanks for that Thanks for that Nigel. I have an SC 120 four stroke I am thinking of using for this.
  13. Next couple of images hopefully shows how this arrangement works; at the front an overlapping locating tongue also with U/C fixings and at the back this is fixed with two nylon bolts into captive nuts.
  14. Then came time to detach the bottom section of the fuselage and in the next image you can see the partially cut sides which just need to be completed to release the bottom section.
  15. Underside of fuselage sheeted back as far as wing trailing edge and undercarriage fitted.
  16. Sorry, just seen your question Jonathan; yes indeed as you can now see, I will post progress as I go...
  17. Base of front fuselage added and then inside on top of that a light ply plate with a ‘V’ section cut out facing back. This is part of the wing alignment/retention setup which I have never come across before, unique to Pete Tindall perhaps? The ‘male’ element of this arrangement is glued to the lower fuselage sides beneath the wing and you can probably see from the image I have used cling film between the two pieces to ensure they don’t get glued together. A bit further down the line, the under wing section will be cut away from the main fuselage and fixed to the bottom of the wing. The trailing edge of the wing is fixed rather more conventionally with two nylon bolts and fixing for this now glued in position.
  18. Well they did say the fuselage build was unconventional, so this is how the firewall is glued in place with just the tail post in position, firewall flat on the bench and fuselage sides then glued to it. By design this is supposed to ensure a straight fuselage, but I dropped a string line down just to be sure.
  19. The instructions start with the flying surfaces, but I’m waiting for some foam friendly cyno to arrive so I’m starting with the fuselage. Popped the various parts out from the laser cut sheets, cleaned them up. Front and rear sections joined and then a doubler overlayed and glued on top, plus longerons also glued to top and bottom edges of fuselage.
  20. I was looking for a four stroke powered aerobatic model, either an ARTF or fairly quick build kit, and came across the Pete Tindall designed Smooth Operator on the Balsa Cabin website; a model essentially based on the CAP 222. Seemed to be just what I was looking for, so put in my order and the kit duly arrived and I have to say, it all looks really nice quality and should be a fairly quick build. According to the instructions the Smooth Operator is a development of the earlier Spin Doctor, the Smooth Operator having a longer fuselage for ‘smoother moveability’. Briefly the kit comprises of: Fuselage all laser cut light ply, Wings, Tailplane, Fin, Front & Rear Deck are Foam Veneered – all good quality, no splitting or rippling of the veneer. There is a very sturdy glass fiber cowl, and undercarriage, a crystal clear canopy, a pair of 3” wheels but no tailwheel, there is also a small accessory pack, instructions and images of the build to compliment the instructions. The website states It’s 62” wingspan and 58” long but doesn't give any indication of a typical weight. Also specifies engines from 90 to 120 4 stroke (instructions say from 52 upwards with the prototype being powered by an MVVS 77) I have an SC 120 looking for a home but do feel that just might be an overkill, a 90 should give good vertical performance I’m thinking. Anyone have any experience with these models with respect to engine size? Here’s all the parts, just need to make a start...
  21. Finally got around to a flight video. Opted for 'launch' by dolly, which works just fine, once in the air, fast and small makes it quite difficult to follow, however, captured enough for a short video...
  22. Thank you Simon, pretty much my train of thought.
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