Stephen Jones Posted January 4, 2014 Share Posted January 4, 2014 It Amazes us what you can do with wood Ian . Quote Link to comment Share on other sites More sharing options...
Lindsay Todd Posted January 4, 2014 Share Posted January 4, 2014 This is a really impressive piece of work. Linds Quote Link to comment Share on other sites More sharing options...
Terry Walters Posted January 5, 2014 Share Posted January 5, 2014 Respect! That's so good that if I didn't have a balsa build list already longer than my expected remaining life span it would encourage me to have a go! Lovely! Terry Quote Link to comment Share on other sites More sharing options...
Martian Posted January 5, 2014 Share Posted January 5, 2014 that is looking really good Simon ,you have captured those graceful lines perfectly Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 6, 2014 Author Share Posted January 6, 2014 A start on the fuselage centre section formers. Although all but the last 3 are the same basic outline due to the curvature of the wing upper surface each is a different height. The really tricky bit will be ensuring the final fuselage surface is straight and true. I fully expect some 'adjustment' will be required to some of the formers. Quote Link to comment Share on other sites More sharing options...
David Tweddle Posted January 7, 2014 Share Posted January 7, 2014 Enthralling work Simon thanks for the input. David Quote Link to comment Share on other sites More sharing options...
Olly P Posted January 7, 2014 Share Posted January 7, 2014 Lovely - You are tempting me to try and do a PSS version.... Quote Link to comment Share on other sites More sharing options...
Monz Posted January 7, 2014 Share Posted January 7, 2014 Posted by Olly P on 07/01/2014 11:03:26: Lovely - You are tempting me to try and do a PSS version.... Do it! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 9, 2014 Author Share Posted January 9, 2014 At this point I realised I would need the tail section to ensure a smooth line is maintained at the joint. The tail started as a half shell over the plan. Once completed it is lifted and the other half formers added. And the planking start all over again. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 10, 2014 Author Share Posted January 10, 2014 With the tail section more or less complete I can put all the bits end to end - albeit only balanced. I fear this will need nearly as much space as the original to to execute a 360 degree turn! The more complete it gets the more I think I made a mistake to use only relatively small elevons at least for the early flights. Roll control is not the problem but it will have so little thrust I expect the CofG will have to spot on to fly at all. The problem is I can only guess at exactly where that might be! At least with a big area of elevators I will be able to set the CofG conservatively forward and still keep the nose up even if the resulting drag means just an 'extended' glide even at full power. My thoughts are to keep the elevons and add inboard elevators operated by a single servo in the fuselage. If my experience with the Fairey Delta is anything to go they will need little travel (& only up?) and are really 'adjustable reflex' surfaces rather than true elevators. Edited By Simon Chaddock on 10/01/2014 13:53:28 Quote Link to comment Share on other sites More sharing options...
Willowlea Posted January 10, 2014 Share Posted January 10, 2014 That looks brilliant Simon!! You are going to need a bigger car though Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 12, 2014 Author Share Posted January 12, 2014 With its small wingspan I am sure the elevons will be adequate for roll control but due to its enormous length I am not sure about its elevator authority. This situation is made worse by its very limited thrust which will probably mean that the CofG will have to be just about optimum to avoid the drag of flying with any permanent up elevator. The problem is I have no way of establishing where the optimum CofG is. The normal method is to set conservatively forward for the initial flight and then slowly work back but if I don't have the elevator power to keep the nose up.............! So I have decided to add scale inboard elevators. They can be joined and driven by a single servo in the fuselage. I intend to keep the elevons as well so it will have virtually double the elevator area which should allow a fairly forward CofG for the maiden. I suspect that if they do have to be significantly deflected the drag created will mean just an extended glide even at full power! This addition has slowed progress as some modifications are required to the wing structure to maintain adequate stiffness. In addition the centre fuselage planking can go no further until the elevators and the servo are installed. Hopefully once the CofG is optimally placed the inboard elevator movement can be greatly reduced although it does raise the intriguing possibility of mixing them with the flap control to raise the nose for landing without sacrificing any elevator power. Quote Link to comment Share on other sites More sharing options...
Martian Posted January 12, 2014 Share Posted January 12, 2014 it's looking brilliant Simon soon be time to maiden Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 13, 2014 Author Share Posted January 13, 2014 I don't think the maiden will be any time soon! To get access one fuselage former is temporarily removed so the elevators can be installed with a substantial thin wall fibreglass connecting tube. A Depron pad has been constructed in the lower fuselage to mount the elevator servo. On another thread someone asked if it was possible to have common earth and power leads. Here with the four ESCs and servos all at the back it would have been possible to have connected each with a positive and earth directly from the ESC BEC and only run one + & - lead forward to the radio along with the 4 signal wires. It would have meant each of the three servos and the radio would have their own individual BEC. I might try it next time! Edited By Simon Chaddock on 13/01/2014 17:38:27 Quote Link to comment Share on other sites More sharing options...
Nev Haycox Posted January 13, 2014 Share Posted January 13, 2014 Looking superb Simon, keep up the good work. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 15, 2014 Author Share Posted January 15, 2014 Spent the day installing the elevator servo and the second pair of EDFs with their ESCs. They all work and blow the right way! They will be installed next. I have done a rough CofG test and to achieve 50% root chord the battery will have to go right at the front of the centre fuselage section which will make the ESC to battery wires about 40" (1m) long! Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted January 15, 2014 Share Posted January 15, 2014 lovely looking model, lets hope it flies as well as it looks. Quote Link to comment Share on other sites More sharing options...
Stephen Grigg Posted January 15, 2014 Share Posted January 15, 2014 Lets hope it flies Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 16, 2014 Author Share Posted January 16, 2014 It may not look like much progress but it does fix quite a lot of what follows. The LH fan unit installed. The solid copper motor conductors and the ESC wires run inside the wing to the fuselage. When the rest of the nacelle is complete it will add to the rigidity of the wing. Quote Link to comment Share on other sites More sharing options...
Terry Walters Posted January 16, 2014 Share Posted January 16, 2014 Coming on really nicely Simon. Excellent work. Terry Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 19, 2014 Author Share Posted January 19, 2014 The full nacelles added. The lower leading edge of the duct is not half going to get a battering on landing! The solid conductor battery wires in the fuselage. The problem is how best to connect the 3 sets of wires together. In this test set up the 3 wires in each connector lie side by side and are pressed together by the screws. This means little or no current actually passes through the connector body itself. An extra capacitor is soldered between the connectors. So far all test running has been done with relatively short (<12" battery leads but the LH inboard fan has stopped working. The fan itself still works (tested on another controller) so it appears the ESC has failed. As they are all identical it does raise the question why? They are 20A ESCs and each motor takes less than 13A so I was not expecting trouble. Quote Link to comment Share on other sites More sharing options...
John Miller 4 Posted January 20, 2014 Share Posted January 20, 2014 Simon I seem to recall a post some time last year about the length of wires from battery to ESC and ESC to motor. From memory I think the opinion of those who are far better qualified than me is that you can extend ESC to motor wires but not battery to ESC as it has a tendency to fry the ESC. I have tried to find the post without any luck. Quote Link to comment Share on other sites More sharing options...
Martian Posted January 20, 2014 Share Posted January 20, 2014 Simon in answer to John's comments I have found this comprehensive explanation HERE Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted January 21, 2014 Author Share Posted January 21, 2014 My problem is in order to cool the ESCs I have to put them in the ducts and with the aft mounted EDFs the battery has to go a long way forward for balance so I am stuck with long ESC to battery wires hence additional capacitors. Having read many of the posts on the subject the capacitors are there to protect the input side of the ESC from voltage spikes initiated by the inductance of the wires reacting to the rapid current pulses taken by the MOSFETS. The longer the wires the bigger the spikes. The capacitors absorb the energy of the spike and then releases it as the spike passes. As the spike gets bigger the capacitor has more work to do so gets hotter and at some point fails usually followed by MOSFETS. Longer leads do not mean instant failure but a reduced ESC life which is why many (me included!) get away with longer leads with no extra capacitors but obviously it also depends on the 'as built' capabilities of the ESC. My Concorde has a 4 into 2 into 1 junction with a long single power wire to the battery. Does this mean that the long part will actually see many more but smaller pulses than if it were supplying a single ESC? I don't know the answer but if this is the case then the extra wire length might not be so much of a problem but I choose to place an additional capacitor, identical to those on the ESCs, at the 2 to1 junction. So far only a quick test but with the battery placed at the 2 to 1 junction it keeps the ESC to battery wire length to less than 12". It makes an interesting noise! Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted January 21, 2014 Share Posted January 21, 2014 Look forward to seeing this one fly Simon . Quote Link to comment Share on other sites More sharing options...
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