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David Hall 9

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  1. This year, I plan to get a couple of my 2m RES kits built, to have a go in the comps that have been organised for 2022. The kits I have are the RES Eagle and the Kavan RESCO (similar to the Circle Dancer). These have a single spoiler. I have a few servos in hand that I would like to use. These are the Blue Arrow D05010MG 6g servos that can produce 1.2Kgcm (but they look quite small). How much torque does the spoiler servo need?
  2. That's a useful product! I might try a sample. For this time, some 02.mm CF is winging its way to me, so I will use this on the larger repair.
  3. I am thinking about how I might repair the damage to a couple of my moulded glider wings. Filling the hole and covering with resin and CF/GF cloth seems to be the standard way to do this. One of the repairs is to a 250mm length of LE back to the spar. It's a hollow construction and has an area where the skin is delaminated from its backing (lots of fiddly work to do). I found some CF sheet material in 0.2mm thickness and wondered if that might be easy to "plate" the open area. I can stand the extra weight and the ease of application and finish are attractive. I can construct a leading edge strip, bridging the gap, and apply the sheets as a top sheet and a bottom sheet, but the preferred option would be to use a sheet which has been pre-bent to the shape of the leading edge. Is there way to mould a cured CF/resin sheet around such a sharp radius (maybe only 3mm)? (I'm thinking woven mat, probably 3K at 200gsm).
  4. Thanks for the info... It occurred to me that, if I use a sheet of (prepared) acetate as the external surface that will give the CF/GF wetted fabric it's shape and finish, might I be better applying the resin and fabric to the sheet, then holding the loaded sheet in place on the wing until set. That would give it a smoother finish?
  5. I have to repair a couple of my moldie F5J gliders, each with damage to the leading edge, with a chunk missing back to the spar. Fortunately, the structure is still sound enough, so I simply need to fill and the skin the wings (one is glass fibre, the other is carbon fibre skinned. For the point at which the wing repair is skinned, I have previously applied CF/GF cloth and sanded down the lumps later. This time, I plan to apply a plastic sheet to the wet cloth and hold in place/shape to give the cured cloth a smooth finish. Can anyone recommend a suitable treatment for the plastic (Acetate/PVC) sheet to release the cured resin? .. Recent efforts with furniture polish have only been partially successful with many specs still stuck the the sheet when removed.
  6. Does anyone know if it's likely that this series of comps will run this year? The dates are booked for the use of the BMFA national venue.
  7. Out of curiosity, I collected together a selection of LEDs. The normal LEDs will not give any light at 1.3v. There are plenty of small bulbs that work off 1.5v, any of these would work, as would the small LED insert from one of those small LED torches that work off a single 1.5v battery.
  8. As an alternative, you could use a pair of AAA cells and another glow clip to just check for a non-blown plug element. (glow clip, LED, series resistor, batteries). Better still, use a 3v lithium coin cell, it can be nice and small then.
  9. Back when we used a 2v lead acid cell for the glow plug, I used a reed relay and an LED to indicate when power was flowing through the glow plug. The LED was mounted in the plastic clip, so it was easily visible as I connected it. It uses a reed relay removed from the plastic body of a door/window alarm magnetic contact (easily available and cheap) with a few turns of wire around the glass relay (see image). I guess that if you use a small LED, it may still visibly indicate with a low voltage battery. You can use fairly heavy wire for the windings (only around 6) so you may not lose too much in the extra wire.
  10. I discharge my 3s LiPo's into a bank of car headlamp bulbs at up to 25A DC, controlling the output current by using a brushed 30A ESC. It works a treat from barely on to full power. I guess that a similar setup would lend itself well to your application on the DC side. A brushed (non-sensored) ESC is pretty much a simple variable pulse width output device. ( I should add that this setup will attempt to provide pulses at full power but of a shorter duration, so not so good for discharging batteries that can't accommodate the full output current. For smaller batteries the load is reduced, reducing the pulse current.)
  11. There are plenty of cheap and surprisingly functional alarms out there. I have one that is armed/disarmed via a keyfob. If it detects entry it can send texts and phone numbers as configured. My daughter recently fitted a front door CCTV system that pings her phone if movement is detected near the door and provides a video on her smart phone. A combination of the two would give some peace of mind. ....... although mine phoned me whilst I was on holiday on Tenerife, so some plan to have local help is required.
  12. Modern switching devices have become very efficient. There are 70A BLHELI_32 ESCs (without BEC) installed in some of my e-gliders that have no heatsinks. They are pushed to 50A working for 30 secs, then very little. They don't even get warm. I think that the heatsink is as much for the BEC, particularly linear BECs.
  13. Interesting thread... I'd like to ask about something that confuses me: I often see posts in which the poster claims to have "scratch built" an airframe using plans or even a short kit. I'm sure that, years ago, a scratch built aircraft was an own design, so, no plans or kit. Did this change?
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