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Simon Chaddock

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Simon Chaddock last won the day on May 13

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  1. I have a problem with static. Maybe its the nylon content in the carpet but after 3 paces from the PC to the printer I frequently quite a crack when I touch any metal part on the printer. I fear for the micro SD card if the discharge occurred over it so I now always touch the vertical lead screw (I know that is earthed) before inserting the card. I have had the printer more than once fail to read the card despite CURA writing to it successfully. So far reformatting the card and reloading the STL has proved successful. I am sure it is only a matter of time before the card will fail completely.
  2. MattyB On the pull/pull for the FX707 and some other lightweights I use 15lb (7kg) monofilament fishing line. Many think it is too "stretchy" but the amount of stretch a 3.7g servo can generate, even when it is stalled, is pretty small. It is also well below the force required to permanently stretch the line so within reason the line stays taught. As a side benefit the slight give in the line provides a degree of protection to the servo gears. I have yet to damage a servo connected by a monofilament line. The same could not be said for the rigid short links I also tend to use. I use one long piece of line to connect the servo and horns. I tie off the line at one elevator horn end. Then pass it through the appropriate end of the servo arm, across to the hole at the other end of the arm and then back to the other elevator horn to be tied off. I have painted the line as it is almost invisible to the camera.😉 With care when tying off you can use the monofilament's stretch to remove any slack but avoid too much tension as it will over load a small servo's bearings as well as the elevator hinges. As the line is free(ish) to pass through the servo arm you can adjust the position of the elevator so it is neutral when the servo is centred. Once happy with the line position it can be permanently fixed with a blob of glue over each servo arm hole. Note on the above installation the line has been "trapped" by the servo arm screw so it can be readjusted at will. Convenient but such clamping is not kind to the monofilament so it will revert to glue in the final setup. I would not recommend using monofilament for anything but lightweights. For serious pull/pull installations you have to use a braided line but with virtually zero "give" you do have to be aware of any geometry issues that might seriously tighten the line at some positions causing bearing overloads or in the worst case actually limiting servo travel. As an aside nylon monofilament line is very "slippery" so it is possible to go round corners using tiny wire eye rings glued into the structure. This Fokker V25 uses a single centre 3.7g servo in the fuselage with a closed loop monofilament pull/pull line to work both ailerons. This requires the line to pass through four 90 degree bends. It even works! It is however a true lightweight. It has a wing span just under half that of the FX707. I look forward to seeing your FX707 in due course.
  3. And it does fly! With the flaps up and with the same CoG position not surprisingly it flies just as well as the my unflapped FX707 so no problem at all. However as soon as flap is applied it quickly runs out of down trim to compensate for the nose up pitch. In some respects I expected this as I normally set a bit more up elevator travel than down. I had the same problem with the Push/Pull which had rather more extreme flaps. There the solution was to set the elevator position so it needed almost full up trim to fly level so increasing the down trim range. I will do the same for the flapped FX707 bur thinking about it I can do a bit better. By moving the servo arm one spline anti clockwise it will impart some mechanical elevator differential movement, more down than up, which will further increase the down trim range all be it at the expense of some up elevator travel. Just as well I had not permanently fixed the push/pull lines. After all the object of the flapped FX707 is to demonstrate its flaps rather than do aerobatics.😉 Unfortunately the weather looks like it could be more than a few days before I can try it.
  4. Just heads up but rapid beeping from an ESC usually means it does not "understand" the throttle signal. This could be there is no signal or more likely the signal frequency is beyond the minimum it expects. Probably the best way to check it is to drive it from a servo tester. The "minimum" signal from a servo tester is often below that from a Tx. At least it would confirm or not whether the ESC works.
  5. Now more or less complete and with such rotten weather I painted the control surfaces. I am still waiting for its 5,3 x 3.3 prop. If necessary it could be flown with the 5x3 fitted. The current weather forecast suggests it could be some time before it can have its maiden. A short video of a full control test. https://www.youtube.com/watch?v=z7KZm0SCYVI With an 850 mAh 3s LiPo it weighs 332g. Which is just 50g more than it did as a chuck glider out of the box.
  6. As above. Clear blue, very little wind but biting cold, even the muddy field wasn't being just frozen solid foot prints in the grass. With this in mind I flew the sub 250g Depron Super Cub, happy that into what little wind there was the landing speed was low enough that even an instant nose over would do no damage. Picture taken summer 3 years ago on my lawn not the rougher flying field. 😉 It still flies well managing nearly 9 minutes before my fingers, even with thin gloves, cried enough. It did indeed nose over as soon as the wheels touched the ground but no damage. Even if I had continued I was worried about the effect of the cold on the LiPo. Although warm when installed straight from the car it was actually cold to the touch of even my chilled fingers when removed immediately after the flight. Say no more.
  7. The CoG applies to full size too. Many years back I flew a commercial flight in an Islander to the Channel Islands. The pilot walked out with passengers and directed each to sit in a particular seat, no argument! The biggest went to seats under the wing. I was only slight so was directed to the rearmost one. Only once all were in did a ground staff remove the prop from under the rear fuselage. Getting the CoG within the range matters.
  8. Mark I use several 6 channel Lemon receivers, as well as the gyro versions, with no problem using my DX6i. This Depron EDF Skyray uses a Gen2 6 channel End Pin.
  9. Flat calm this morning if not a little chilly, like -5C! Perfect condition to fly the simple but effective Big Dragon. Depron flying surfaces with the pod and wing pylon printed. Light and aerodynamically pretty efficient it was designed to land on a rough grass field. A nice 22 minutes floating about apart from doing its "party" piece, repeated near vertical climbs to 400 feet. Very relaxing as it glides so slowly.
  10. toto The thing to remember about snakes is they work best in a straight line so there is little rubbing between the inner and outer, Any curve means the inner and outer must rub together. The tighter the radius the worse it gets. Then throw in the fact the snake is pulling and pushing against a control surface load and the rubbing forces rise rapidly. The plastic used in snakes may be 'slippery' with a low coefficient of friction but any friction in a control run is not a good thing. Supporting the outer along its length is good provided it keeps any change of direction to a minimum. What is mechanically essential for a snake to avoid "give" is that each end of the outer must be absolutely secure in the fuselage or wing structure. Now if you can arrange for the servo to be close to the control surface.............. 😉
  11. At 12 degrees the LW-PLA the body of the print will cool significantly. Remember it is laid down at 245degrees! The majority of the contraction will be across the line of the beads causing the item to lift of the bed. This problem is not so severe with the lower temperature of ordinary PLA. The classic solution for high temperature printing is to print inside a hot cabinet so the print does not suffer such quick cooling. For many printers this means the cabinet has to encompass the entire machine. Done like this some of its electronics may not take kindly to running for long periods at elevated temperatures. Alternatively keep the area where the machine is used at "sunny summer" temperatures like 25 degrees.
  12. The cowling and motor with the printed mount glued onto the cut off nose. The ducts matching the holes in the motor mount exit into the cockpit. This layout ensures the air from the nose inlet will travel across the motor, hopefully. Just as well it is only a 100W motor! The "exits to air" will be added further down the fuselage. ESC next, likely to bed semi recessed externally as in my first FX707.
  13. Albert Ace I would strongly suggest you use a 70 mm EDF in order to keep the existing thrust tube. It is likely to be reasonably efficient as the original brushed motor would likely have had limited power. Be aware that not all 70 mm EDFs are equal. All you will need is a 'modest' power brushless one. It will probably be quite a lighter than the brushed one. If you go for a 64mm it will need a smaller diameter thrust tube and nozzle. You can easily loose quite a bit of thrust if you get the thrust tube dimensions wrong. Just an observation based on my planes using relatively low powered EDFs.
  14. Daren As you can see from the replies polystyrene 'packing' foam has very little "structural" strength so it use is all about how it is reinforced. Obviously adding reinforcing to the surface of the foam is gives the best stiffness to weight ratio but it needs experience to use the right material(s) in the right way. Adding a high strength material like a carbon tube is relatively simple to do but provides no protection to the foam's soft outer surface. A combination of both of these techniques may provide the best solution. Using soft foam to build a plane, although it may be plentiful and free, is not quite as simple as it might appear.
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