Dave Hopkin Posted April 29, 2017 Share Posted April 29, 2017 Its something I have been thinking about for a while but finally put started converting balsa to dust...... Wanted to try a battery tray that slides in and out to avoid hatches that always seem too visible and the big radial cowl on this seemed to be perfect for it As the battery will be when flying (if indeed it does!) And as it will be to change Lipos The plan is to secure the whole motor/battery tray with two bolts from underneath into the captive nuts above the tray.... Planning to use a Turnigy G60 300kv on with a 5S 5000 Lipo and something like a 16" prop..... thats the guess at the moment Quote Link to comment Share on other sites More sharing options...
kc Posted May 1, 2017 Share Posted May 1, 2017 Looks a neat idea Dave but won't it be a bit hazardous to grip the cowl & pull the whole front out whilst that 16 inch prop is still live? Also the ESC to RX lead will move around too. Quote Link to comment Share on other sites More sharing options...
Jon Laughton Posted May 1, 2017 Share Posted May 1, 2017 Balsa & ply Dave? Did you run out of Depron....😉? Going IC next? Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 2, 2017 Author Share Posted May 2, 2017 Posted by Jon Laughton on 01/05/2017 23:02:44: Balsa & ply Dave? Did you run out of Depron....😉? Going IC next? a) Yep b) Never! Why would I go backwards to 19th century technology? Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 2, 2017 Author Share Posted May 2, 2017 Posted by kc on 01/05/2017 10:54:41: Looks a neat idea Dave but won't it be a bit hazardous to grip the cowl & pull the whole front out whilst that 16 inch prop is still live? Also the ESC to RX lead will move around too. The ESC will be inside the sliding tray so in a fixed position in relation to the motor with a long lead to the RX to allow for the tray to be pulled out The cowl is fixed to the airframe, the front of the tray slides out through the front of the cowl - yes there is an element of risk - that cannot be denied - but as I the battery is connected with the tray extended and hands clear of the prop then the tray slides in (that being the risk point) the ESC would have to go faulty AFTER connecting the battery in the few seconds while the tray was being slid in - and during that time the throttle lever will be at zero and the throttle cut switch set to zero.- I dont think there is any more risk than starting an IC engine to be honest Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 2, 2017 Author Share Posted May 2, 2017 Posted by kc on 01/05/2017 10:54:41: Looks a neat idea Dave but won't it be a bit hazardous to grip the cowl & pull the whole front out whilst that 16 inch prop is still live? Also the ESC to RX lead will move around too. Your comments have had me mulling all day in the office....... The solution: There is a hatch underneath between the undercarriage legs, where the tray fixing bolts go, there is plenty of space to fit a circuit break point - i.e. the +ve from the ESC to a female connector mounted (mouth down) at the rear of the tray, next to it will be a second female running to the battery connector - there will be holes aligned so when the tray is fully inserted the two female bullet connectors will be visible when the hatch is removed - a short length of wire with a male bullet at each end will arm the circuit - without it the plane will be dead - so the link can be pulled without going near the prop - best make a spare link up too!!!! Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 7, 2017 Author Share Posted May 7, 2017 Plodding - Power train safety interlock added and tail plane/fin fixed in place (elevator and rudder loose) - some fettling to do to get the fin to fit snugly against the tail post - Fuselage in the process of being covered in PVA's Brown paper (to reduce hanger rash while the wings are made) Details of the safety interlock Hatch underneath gives access to the battery box bolts and the arming lead - dummy air scoop makes a nice handle for the hatch! Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 14, 2017 Author Share Posted May 14, 2017 Dont know if anyones taking any interest or not, but the wings are underway - not going to skin them till I have fettled all the geometry but this is a rough set up .. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted May 16, 2017 Share Posted May 16, 2017 Watching with interest Dave, and like many others, I have just not commented until now. It will be a fine spectacle in the air, and be assured that your techniques will be copied Heads up on the undercarriage. Brass tube is a design solution as it it accurately formed and self lubricating, where it will slide freely and we can be drawn to it Big BUT, at our dimensions and wall thicknesses, brass is very weak in this application. Even the best landing has a split second duration of shock, towards the belly and towards the tail. I can see that you have used best practice alignment and mounting, but my efforts with brass in the past have failed on the 1 st touchdown, the Storch u/c I had, similar construction to yours lasted a millisecond. Currently, have got 3 articulated, cheap solutions on the bench that I will report to you once airborne With respect, this information is to heads up for the maiden landing Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 29, 2017 Author Share Posted May 29, 2017 The brass tubing is decorative only, it pivots and both the fuselage and wheel ends and telescopes in the middle - the main legs are both torsion bars with a sprung oleo on them - so (in theory) the rear brass struts wont have any force on them at all as they wont offer any resistance...... (famous last words!!!) Anyway been plodding on with the wings - now joined (and already accumulating hanger rash!) Joining them was a bit of a mare - in the end I joined them before the leading edge was added - by securely taping a long carbon fibre tube to the false leading egde then taping the second wing in the same way - so that both outer panels were aligned - then it was a case of jacking the inner panels trailing edges to get a 0 incidence across the outers - when I was happy with that I (very gingerly) CA'd some bridging pieces to hold them in place - then slapped some fibre glass across the wing join - and the same on the underside Now just a question of adding the decking over the glassed area and back to the brown paper!!! Cowl is "black" as I was seeing what a rattle can I had looked like - far too dark!!!! Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted May 29, 2017 Author Share Posted May 29, 2017 The weights so far (plan for a .6o is 9lb is (including LiPo) 7.7lb so on target!!!! The motor is a Turnughy G60 on a 5S 5000 - gives around 1100 watts on a 14x6 - thats around 130W/lb so should have plenty on power (and I can up it to a 15" if I need more) Quote Link to comment Share on other sites More sharing options...
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