Simon Chaddock

Richard The reason I asked about the power plant was that for a Gipsy powered plane the prop rotates clockwise when view from the front. This is the reason that the nose cowling inlet is offset to aid the cooling airflow. When a conventional CCW prop with a scale nose cowling means the cooling airflow is by comparison somewhat restricted, exactly the point raised by Manish. Of course the cooling may still prove to be adequate but it does rather depend on just how scale you want to be. Its a bit like the issue of using true scale wing sections.

The weather has effectively stopped any more testing until a) the field has dried out a bit and b) the wind is less than 5knots! Going through the plans I noted that my long printed nose is about 50 mm to short and even worse the front part of the fuselage is not quite the right shape. 😟 Given that the next flight(s?) will always use the short nose cone I will leave the current fuselage nose shape as is for the moment, particularly as there is a fair chance it will have to be rebuilt anyway. I did however print the new longer nose and it also matches the correct fuselage nose profile, as and when it gets done. Not noticeable but at the base it is also a bit taller and wider than the original nose. Of course it is still impossibly fragile so unlikely to ever actually fly more than once!

Richard That is truly spectacular scale detail. Any thoughts on how and what is going to power it?

As always very weather dependent for me but if the wind is gentle enough I will be there with at least two "new to the site" home built foam planes.

Yes toto By Saturday the forecast shows high pressure centred over the UK which means light winds and generally clear skies however the air is still being drawn from the north so it will be cold (11/12C), not the balmy 19/20C we had last week end. Hopefully the winds will be light enough for another try of lightweight Douglas X-3 Stiletto.

Is it not the "pilot" of an RC plane (UAV) who is responsible for its safe operation? For most clubs the CAA recognise it is unlikely a club could meet the full responsibilities as the "operator". From the CAA Introduction to drone flying and the UK rules. "Since the legal identity of the operator must be clear, organisations or clubs without a formal legal status are unlikely to be able to meet the operator requirements." If this is the case it follows that the legal responsibility for a flight lies with the UAV pilot unless he is a minor in which case the responsibility is the registered "operator" of the UAV. It will be interesting to see what is the BMFA view.

Neddy Being sub 250 g I used 3.7g micro servos. They are small enough to to be completely buried in the wing and the fin giving short control rods. The aileron servo . This picture was taken today. The elevator servo. This pictures is over a year old, note the substantial glue repair after the RH tail plane was "dislodged" after a crash. It still looks like that today. I really must get round to "making good" the fin skin around the servo arm! The "Light Tractor" has been well used. It will be 9 years old next month. The wing has little dihedral, which makes it remarkably "responsive" and being so light I considered ailerons a must over a rudder. https://www.youtube.com/watch?v=-8sYWG-agnU

Some weeks back on one of the calmer days I flew my sub 250g 40mm EDF Depron DH Venom. Unfortunately I briefly lost sight of it when end on (it is small) and ended up woth a nose plant! It has been hanging on the wall since but as the weather has terminated flying such light weights or even middle weights I spent some time putting is back together. First the damaged planking was cut back to a clean edge and a suitable Depron former added on the end of the battery compartment. Then came the tricky job of adding planking "extensions" to reach the former and all done with small 2mm Depron pieces carefully "formed" to give the right fuselage shape. With a bit of sanding & light weight filler. This time the nose cone was printed in LW-PLA. Even with a double wall thickness it was no heavier than the single wall PLA of the original. It is a great deal stronger. Two light coats of acrylic purple on the rebuilt part. It is ready to go even if the weather isn't.☹️ Maybe I will get some more EDF practice soon, although not for a week or so according to the forecast.

When you start out with electric limited flight time seems to be a constant problem. As you progress with more capable planes with a longer potential duration you find what you want to do in the course of the flight is more important than the maximum possible flight time. I suffered from exactly the "duration" problem when I started out in electric where 3 minutes was likely the best flight time for a simple plane. My interest in structures and aerodynamics prompted me to do something about it. Improvement in wing aerodynamic efficiency and weight reduction more than doubled the duration of the same basic plane to 8 minutes, mostly due to the reduced throttle required to simply stay up. The full power duration was little changed. I carried on with this theme with several versions of an improved lighter airframe, more efficient motor and prop with of course a bigger battery. Although keeping to the same span as the original plane a cruise duration of an hour was achieved then a theoretical 2 hours and finally this plane which has a potential "power on" cruise duration of nearly 4 hours. It has a 1200mm (47") span and it weighs 436g (15.4oz) with a 3800mAh 2s. Its maximum duration was never tested as after 2 hours on a flat site I gave up from boredom and a stiff neck. Maybe it ended up to be a rather pointless exercise however I do still fly it on calmer days safe in the knowledge that the one thing I do not have to worry about is how long it has been in the air.😉

toto Much of the weather problem when learning to fly is the need for the right weather on the right day. I remember the frustration learning to fly full size gliders. Although they of course were dual dual control so the actual flying bit once in the air was not such a problem but actually doing the take and landing was weather dependent and it is the take off (aero tow) and the landing that needs the most practise. The weather in the UK has always been a frustration to flying.

I have prepared a couple more EDFs to practise on but the weather says otherwise and likely so for a few more days yet. You never know it might eventually get calm enough to try the Douglas X3 again which was after all the reason for the EDF practise.

Robert The conventional wisdom is that high capacity AA NiMh cells have a high internal resistance so have to be charged and discharged very slowly to reach their claimed capacity. There is of course no guarantee how or even if the manufacturer ever achieved what "It says on the tin". If you are getting out what you put in at the sort of rates you are using then that likely the best you will get. If you know the actual discharge rate your TX requires and use that for both the charge and discharge you see a higher capacity. Remember the old NiCd AA cells were only 500mAh. They did have that capacity and with a lower internal resistance could deliver a good 10C (5A) at a push.

I find hard to believe an effective silencer is not possible particularly as a 4 stoke is much better able to handle exhaust back pressure than a 2 stroke. Is it just a case of providing the space for the necessary can volume?

I can only advise that you put equal thought into keeping down the weight of the Bearcat's pretty "tubby" fuselage. The lighter the overall weight the less power you need and the lower the stress on the wing. A quick strength test. When complete and including the battery try picking it up by just its wing tips. If this can be done without the structure making to many 'stress' noises it will put a bending load on the wing equivalent to pulling 4g or doing a 'proper' circular loop. If it feels like the wing is going to break before the plane is fully lifted then stop. The plane can still be flown but steer clear of any rapid or substantial elevator stick movements! I have physically tested all my planes this way except the Depron 2.1m span Antonov AN124. With a thrust to weight of just 0.4 : 1 it simply does not have the push for aerobatics but then neither does the full size.😉

250g is not bad at all for such a big span and chord wing.