Peter Jenkins

Interesting.

Problem must be at my end then! Thing is, no other website I'm using has this problem. Odd.

Is it just me? Over the past few days, despite having a brand spanking new PC that goes like the clappers, when I access this website the response is very slow. Is there something I should do to sort this or is this a real problem at the other end?

Keith Jackson, who writes the Aerobatics column in RCM&E, has posted his review of this book in the July Edition of RCM&E. My copy hit my door mat this afternoon. Worth taking a look at it - see page 46. I think Keith liked it! I have copies in stock so, if you want to buy one, please send me a PM.

Hi Geoff There is normally no switch between the flight pack and the ESC as a switch capable of handling 100 amps is very expensive! The normal procedure is: ▪︎ Tx on ▪︎ Rx on and bound ▪︎ plug in the flight pack and listen out for the tones to indicate the ESC has armed. Some folks have the throttle set so low so that the ESC won't arm and consider the aircraft to be safe. I oppose this strongly as you are relying on the Tx software to carry out a safety critical function for which it has not been designed or qualified. To do so would add hugely to the cost of our Tx equipment. Another way of providing you with a physical "kill switch" is to route one wire from the battery and ESC to outside the aircraft. You can then just plug them together to arm the ESC with the aircraft on the runway. You can also disarm on landing by unplugging this lead. This allows you to fit the flight pack into the aircraft and secure the canopy with complete safety as the power circuit has not been closed till you plug in the external leads.

You mention a kill switch but I'm not aware of what you mean. There are main flight pack switches available but they are eye wateringly expensive ~ £200 for up to 100 amps switch. I use the Tx to provide the "kill switch". This is not a genuine kill switch in that it is based on software to prevent the throttle stick signal to be sent out but it at least prevents the motor bursting into life if you move the throttle stick inadvertently while transporting a live electric model. I have seen people use a very low throttle position that prevents the ESC from arming with the flight pack attached. This is a false indicator that the model is not live. The only way to treat electric power is that once the flight battery is connected then the aircraft is live.

I suspect that what you wanted is this one below. If you want to add 2 batteries to the Rx there is the option to use a thing called an Optiguard (link) that you just plug into a spare Rx slot or via a Y lead. The gubbins in the Optiguard checks the Rx battery voltage and then sets itself to come on if the Rx battery voltage drops below its safe level. You can add a high intensity flasher that you should attach to the model so that when the Optiguard kicks in the flasher starts to work. I place mine by an air outlet so that I can see it is flashing when the aircraft is flying. You also need to switch off the Optiguard using the small press button switch on the PCB but you can buy and extension switch that you can plug into the Optiguard and place where it is convenient for you to operate it. I use one of these. For a switch I use the Digiswitch. This is a software controlled switch so will not suffer mechanical switch malfunction. As I use LiPo packs I remove the Rx battery to charge it so there is no charge switch included. The Digiswitch also gives a visual indication via its indicator lamp of battery condition.

+1 on lower Reynolds number Simon. I would think that model gliders would normally be in the laminar boundary layer flow Re regime whereas the full size would be in the turbulent boundary layer regime.

Having spent many years in full size soaring, I completely agree with you Konrad. I would also add that when the move to glass fibre construction was introduced, there were two great advantages. Firstly, the aerofoil shape of a the flying surfaces were hugely improved, the surface roughness greatly reduced and great care taken to seal all joints e.g. between wing and fuselage and also the control surface gaps as well as keeping as much of the control surface pushrods either shrouded or kept inside the structure. We would even go the the lengths of washing and polishing the glider to remove any dead insect debris from leading edges and smooth out any small imperfections with the polish.. I remember also outclimbing a glass ship when flying a K6e wooden glider but seeing the glass machine disappear upwards as we chased after the next thermal! I had a glide angle of 1:35 (I think) while his was better than 1:48. In fact the very best glass gliders in those days (early 80s) were 1:55! I've no idea whether that has been surpassed now but it wouldn't surprise me. I suspect the biggest problem with model size gliders is that with narrow chord wings the Reynolds number might languish in the laminar flow region although using turbulators or vortex generators might ensure that the transition to a turbulent boundary layer is achieved. I well remember with a particular glass glider the warning that if you got the wing wet in rain to expect the stalling speed to rise from 40 knots to 55 knots! So, they were clearly subject to being on the cusp of the laminar/turbulent transition. Oh, and having glass fibre wings allowed water to be poured into the wings to improve penetration on high lift days but you had to leave time to drain the water in flight before landing or if the lift was no longer so strong.

If you go to the BMFA website and click on "About Us" and then, low down on the RHS, click on "Associated Bodies" you'll find that the LMA and SAA are now Associated Bodies of the BMFA. As Robin points out, this is primarily about insurance so that the existing BMFA Insurance now covers the LMA and SAA. As such, you must now be a member of both it you fly model aircraft. If you turn up to help at an LMA event and are not flying then you don't need to be a BMFA member. But, if you fly then you must be a member of both BMFA and LMA in order to be covered by the insurance. The LMA is, therefore, part of the BMFA and continues to provide the advice and inspection services that they have always offered for all model aircraft in excess of 25 Kg MAUW. In a way, this is similar to the BMFA's Specialist Bodies which number 18 and span a whole series of disciplines from helicopters through drones to aerobatics, where you join both as only BMFA membership provides insurance plus all the other services of the BMFA that are augmented by the LMA with its services.

Looks very realistic Flying Squirrel. Reminded me of my days in the ATC.

What note should you expect to hear when you pluck the wires to make sure the tension is correct?

You can always find this one on Amazon or PM me! Last updated in Jan 2025. 😁

Paul You clearly know little about this subject so just give it a rest.

You really do write very provocatively. Try looking it up on the web mate!