Simon Chaddock Posted January 30, 2015 Share Posted January 30, 2015 My normal rule is "Do not start the next build until the last one is flying properly" however as far as the Canberra is concerned the winter weather has defeated me! So another small EDF! With its small Goblin turbo jet the Vampire inlets and exhausts are hopeless for an EDF but as it had a larg diameter centrifugal compressor, unlike the Canberra, an EDF will fit easily enough. For a number of reasons this build will start from a FF balsa kit, actually a 25" span design originally published by Jetex themselves to be powered not surprisingly by a Jetex 100. My idea is to convert it to an EDF and RC. The original plan as downloaded from Outerzone. Really only 'stand off ' scale but simple enough construction. The 'printwood' formers are included in the download. A quick look suggested a 40mm EDF would just about fit. The exhaust duct shown would be 85% of the FSA and the combined area of the inlets would be close to 100% FSA. Good enough! The plan was going to need quite a few alterations. First the huge FF dihedral could be reduced to scale proportions and then a symmetrical section tailplane along with working out how to actually fit the EDF and its duct inside the fuselage. Finally the down loaded plan was not very accurate as in some views the L&R sides were different sizes! I had to resort to 'select/copy/flip/paste to make sure both side in all the view were truly identical. After a couple of hours playing on the PC. Still just about recognisable as the Jetex Vampire. The fuselage comes first. Edited By Simon Chaddock on 30/01/2015 15:22:09 Quote Link to comment Share on other sites More sharing options...
Jon H Posted January 30, 2015 Share Posted January 30, 2015 what fan unit is teeny enough for that? Quote Link to comment Share on other sites More sharing options...
Paul McCaughey Posted January 30, 2015 Share Posted January 30, 2015 he could go smaller and use one of these 28mm units. **LINK** good luck, will keep an eye on this. Quote Link to comment Share on other sites More sharing options...
Bill_B Posted January 30, 2015 Share Posted January 30, 2015 This one: Quote Link to comment Share on other sites More sharing options...
Wingman Posted January 30, 2015 Share Posted January 30, 2015 Ooo that little Habu in Pauls link could be fun Quote Link to comment Share on other sites More sharing options...
Eamonn Fahey Posted January 30, 2015 Share Posted January 30, 2015 Wingman, the little UMX Habu is great fun. Small enough to fly on a 'tennis court' sized piece of ground yet can be flown almost anywhere if your eyesight is good. The UMX Pitts S-1S is a better flying model. Quote Link to comment Share on other sites More sharing options...
Monz Posted January 30, 2015 Share Posted January 30, 2015 If you want great micro EDF units, these are the ones to get: **LINK** Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 30, 2015 Author Share Posted January 30, 2015 The other reason I chose this particular plan was I already had a 40mm fan and ESC bought as spares for my Depron Concorde and a featherweight Lemon 4ch 2.4 radio. The intention is to use the same battery as the Canberra so apart from a couple of 2.5g servos all the electrics are sorted. I am a firm believer in 'light' rather than 'powerful' which in electric terms means it is easier to get significant endurance so my fan is more modest (and cheaper) than Bill's suggestion - an AEO 6 blade unit. It may only deliver 4oz thrust but it weighs half as much and only draws 10A on a 2s. Continuing the lighter theme the Vampire will still be tissue covered but the structure a 'composite' of Depron and balsa. Well that's the plan. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted January 30, 2015 Share Posted January 30, 2015 I like the idea of composite balsa and Depron with a tissue or on the larger types, silk, nylon or even film covering. Enormous potential here, I hope that more pick up on the idea. Surface has only been scratched so far. Another great subject Simon, I note it's based on the original Mk1 with rectangular fins and long span wings. I've got a brand new Jetex PAA Loader still in the box if you want to try it! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 31, 2015 Author Share Posted January 31, 2015 Colin You got me puzzled with the reference to long span wings. As far as I have been able to find out the wing remained unchanged until the advent of the FB5 when the rounded tips were clipped back by a foot and the new fin shape with 'acorn' fairings were added. On with the build. The fuselage is being built on and around the EDF itself. All the formers will be 3mm Depron. To give an idea of size the fuselage is 10.5" (265mm) long The paper thrust tube is formed around a turned wooden mandrel. The thrust tube supports formers F7 & F8. In conjunction with F6 these formers support the wing root rib which in turn support formers F4 & F5. Before the fuselage goes any further the internal bifurcated inlet duct (in 2mm Depron) has to be put in place. Far to complicated (for me anyway!) to attempt to draw out so it will have to be fabricated piecemeal by eye! Edited By Simon Chaddock on 31/01/2015 23:41:18 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted February 1, 2015 Share Posted February 1, 2015 Hi Simon. The "pointed" fins replaced the original shape on the second production version of the Vampire, the F3, in 1946, along with a lower tailplane. The F2 had the original fins and a Nene engine, but didn't go into service with the RAF. You're right about the wings, the main production version was the FB5 and that had the shorter wings. What you're building is the original F1. Nothing wrong with that mate. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 1, 2015 Author Share Posted February 1, 2015 Ever so fiddly to do and not to easy to see but the bifurcated duct goes in. The big advantage is that the duct adds significant rigidity to the structure ahead of EDF, indeed, when the Depron battery box is added all the fuselage formers will end up internally supported. The balsa stringers will thus just provide the surface outline and support the tissue. As a structure it is the exact opposite of my usual 'empty' stressed skin monocoque! . Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 6, 2015 Author Share Posted February 6, 2015 The 2x1mm stringers started. Each slot in the former is cut with a 1/32" diamond jewellers file which cuts the Depron very easily. The stringer is a tight fit which holds it in place while the POR sets. The fuselage stringing complete. The wing is Depron with 3mm ribs, 6mm leading and 2mm trailing edge. The spar has 2x1mm Balsa flanges with 2mm Depron shear web between the ribs. It is amazing just how little balsa is actually being used! Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted February 6, 2015 Share Posted February 6, 2015 It is just amazing watching you work with depron at these sizes. a true master at work. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 7, 2015 Author Share Posted February 7, 2015 As Depron is more flexible than balsa it needs aditional support between the ribs to resist the shrink forces of the tissue. By using braces rather than gussets it is possible to support the trailing edge at both 1/3 and 2/3 the distance between the ribs. The thicker leading edge only needs support at the mid point and being full diagonal bracing it also provides significant drag stiffness to the structure. The wing root inlet is made of 2mm Depron. It also adds considerable strength and stiffness to the wing root.. Having worked out how to ake one wing I have just got to make another the same! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 13, 2015 Author Share Posted February 13, 2015 The complete wing. Exactly 25" (635mm) span. It may look odd with all the bracing but it is required when using Depron leading and trailing edges yet it adds very little weight, just over 1g for all the bracing. The big diagonal rib is to provide support for booms. In fact the wing very little balsa in it just 4 strips of 2x1mm. All the rest is Depron. The booms are a built up hollow Depron 'tubes' sanded to shape but with an inset 2x1mm balsa 'spar' top and bottom. Not easy to take a picture of the inside of the boom. Each boom weighs 0.07oz (1.9g) The tail feathers are next. Edited By Simon Chaddock on 13/02/2015 00:06:59 Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted February 13, 2015 Share Posted February 13, 2015 Beatifull stuff Simon, just one question.... do you ever sleep? How you get the speed with that level of quality baffles me! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 13, 2015 Author Share Posted February 13, 2015 Speed? Well it is very small and being retired helps! For sheer 'bulk' speed you only have to look at Tony's builds! The tiny Lemon 4ch 'featherweight' is simply glued to the back of the wing spar. The 13A fuse gives some ides of the size. Strictly it is a "shockie" radio but the Vampire is so small you wont be able to see it very far away. The 2.5g aileron servo just fits within the wing. It lies flush with the wing underside. Once both aileron servos are in and tested the wings can be 'tissued' As this stage it looks like it should weigh about 5oz 140g) all up with a 950mAh 2s. Edited By Simon Chaddock on 13/02/2015 21:30:37 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted February 13, 2015 Share Posted February 13, 2015 Composite builds could be the future! I'm on board. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 15, 2015 Author Share Posted February 15, 2015 Covering the wings allowed the boom to glued on, although the area over the radio had to be left off. With the boom in place all the installation of the radio could be completed and tested. Then I discovered I had run out of model memories on my DX6i and the servo direction was different to all the other aileron/elevator planes so I cannot even 'double up' on an existing memory! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 17, 2015 Author Share Posted February 17, 2015 Slow progress the bits seem to get ever more fiddly. The aileron top tape hinged. All Depron except the leading edge. The battery hatch and the windscreen. Like the fuselage all Depron except for the stringers. I fear I will have to mould the remaining part of the canopy! The 950mAh 2s in place with the JST connector lying on top. Its all a pretty tight fit. Quote Link to comment Share on other sites More sharing options...
Keith Simmons Posted February 17, 2015 Share Posted February 17, 2015 Hi Simon Is the CG on the main spar position? I can't see the CG location on the plan at the beginning of the thread. I am hooked to the lovely idea of Depron/balsa construction & I do believe that's the way to go, expecialy to the rear end to avoid the lead weights up front. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 17, 2015 Author Share Posted February 17, 2015 Keith There is no mention of the CofG on the plan. I expect the original instructions did but they are not included. I would expect placing the CofG on the main spar at the wing root would be something like right. I will probably set it up a bit ahead of that as I am using a symmetrical tailplane whereas the original had a lifting section. The mixed Depron/stringer construction is interesting and works well but I have a sneaking suspicion that by the time the tissue is water proofed and painted it will actually be slightly heavier than if the whole thing had been simply sheeted in 2mm Depron with balsa used just in the spar flanges. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 19, 2015 Author Share Posted February 19, 2015 More or less complete. The paint has added 0.22 oz (6.5 g) so it now weighs 4,25 oz (127 g). This gives a wing loading of exactly 7 oz/sqft. This rather higher than the 4,5 oz/sqft of the Canberra but the Vampire's 60% thrust to weight ratio is marginally better. It is going to 'feel' rather different in the air. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted February 23, 2015 Author Share Posted February 23, 2015 Now complete just waiting for the right weather. Inside of the jet pipe painted black 3 stringers over the ESC that follow the fuselage line. Wing roundels added but those on the boom and the fin flashes will have to wait! Quote Link to comment Share on other sites More sharing options...
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