Peter Jenkins

Sorry Ron, I'd have to disagree with you. For F3A work with this class of motor you are looking at a 21x13 or there abouts. Adrian, if you have a 20 x 10, by all means try that and check the current draw. From my experience of comparing ground tethered runs and airborne max power figures, you would quite safely aim for 85 amps on the ground tethered at WOT. That will drop back in flight to under the 78 amp max quoted for the motor. If your Capiche comes in at 5.5 Kg with the flight pack then you should get close to unlimited vertical with the right prop. The 16x8 prop is way too small for proper aerobatics I'm afraid.

John, my gut feel is that the term power tuned pipe has more to do with marketing than actuality. A proper tuned pipe is much longer and will be a convergent/divergent shape with a baffle to reflect back the shock wave from the exhaust port. I was told Weston that a tuned pipe is a pain if you wanted to fly at different power settings as opposed to the speed or pylon racers. Also, throttling was very poor as the pipe came on and went off as you throttled the engine. I've tried DLE cans and while they do work they didn't bring the noise level down to the required 82 db. The more expensive ones are, in reality, better value for money as they will usually get you through the noise test and sound better. Alternatively, go the route of using a secondary mini can as was covered in the mag recently and that might work out cheaper than using the more expensive option but will require a good deal of work to get a satisfactory installaton. So, if you go for the cheaper of the two you could buy the smaller silencer, I think it was about £10 plus postage. and you might be in business after a bit of jiggery pokery.

There has been a slight delay while I ponder two issues. The first is the placement of the main retracts and the second is the issue of using Oracover Chrome. On the issue of the retracts, as I'm going to be using two doors, I need to make sure I have a workable solution before starting the wing build. This is what I'm going to have to accommodate: The blue board, in between the 2 wheels, is the Turnigy retract and door timing controller while the red coloured box connected to the retract is the Robart control box for their electric retracts. After pondering how I might combine these two contollers, a light went on in my brain - yes, I know! The blue control box will control the door servos and provide the timing while the Robart control box will control the retracts and both will be on a Y lead originating from the Gear Channel of the Rx. The door servo will move much more quickly than the retract servo and there is a slight delay in the retract beginning to operate once the command has been issued. To be absolutely sure this will all work in practice, I've decided to build a mockup of the part of the wing from the centre line to the end of the retract. This will allow me to check how deeply to position the retract so that the door attached to the leg lies flush with the wing and secondly to construct the inner gear door and test out the geometry for the servo linkage to open and close the door. My gut feel is that I might need a fairly powerful digital servo as the inner doors are quite large and may require a bit of force to operate in flight as well as to hold the commanded position against any blow back. That indicates a digital rather than an analogue servo to avoid any chance of blow back. There is no clear statement as to whether Oracover Chrome will block the radio signal so I will build a small box, cover it with Chrome, install the Rx and aerials inside it and then see is the Rx range is still the same as the original range in range check mode. If this fails, then the option will be to hide the Rx aerials on the external skin of the fuselage using some of the markings to hide the aerial. My first thoughts are to put some black trim to simulate the canopy track behind the canopy and the black squadron numbers to provide the orthogonal requirement for aerial mounting. The only problem will be the secondary Rx which on my 11 Ch JR DMSS set up has no external aerials. The secondary Rx also provides the telemetry transmission so that will let me know if the Rx transmission is working as well during the test. Edited By Peter Jenkins on 09/04/2020 23:17:00

I endorse Richard's view.

Hi Adrian, you can swap the UnisensE from model to model very easily. So, if you get one you can use it to check the performance of all your electric fleet. For me now, it is essential equipment for setting up electric motors as ground testing has proven to give false readings. The only readings that matter are only obtainable in flight. True, the ground test errs on the side of safety but you risk losing up to 25% of power that you can safely extract but have no way of finding out about without on-board telemetry.

kc, forgive me if I'm teaching you to suck eggs! Dan's design is based on one used by the current world champion and there are others that have even larger fuselages. What these designs are all seeking to do is to provide as good a performance in knife edge as the FAI F schedule contains a large number of knife edge and compound manoeuvres. The amount of fuselage side area helps greatly when you are performing KE loops or horizontal circles. The other issue is drag and today's aircraft are flown at as near a constant speed as possible whether climbing, diving or flying straight and level. Drag in the downline is also complemented by prop braking either from the ESC/motor or from an IC engine idling. I can't find a way of attaching a document so I will leave you with a link to the FAI Sporting Code. Go to page 26 for the description of the manoeuvres in F21 and to page 35 for an Aresti diagram of the schedule. I hope that will answer your question as to why a bulky fuselage is needed in modern F3A aerobatics. Of course, there is also the matter of fashion. Some pilots love canalysers, others don't. If the world champion is using some aerodynamic tweak then everyone else will also want what ever advantage there is to be gained from the design. At the end of the day though, it is down to the amount of practice the pilot puts in and the ability to perform at your best when under pressure.

One other point to bear in mind. What ever results you get on power and current draw when the aircraft is on the ground and tethered is greatly reduced once the aircraft is airborne. I have a Hacker Q80 in a Citrin biplane that recorded 3600 watts tethered but very occasionally touches 2,800 watts in flight. I use an on-board monitoring system that records max values that can be inspected on the ground or you can take a glance at the instantaneous reading while in flight - not to be recommended unless going vertically upwards at the time! If you don't have flight pack volts/amps telemetry consider this device from SM Modelbau called the Unisens-E. If you follow this link you can download an English translation of a range of products including Unisens-E. There is also a product that carries a micro SD card that records all your flights and that you can play back on a PC. Incidentally, this very versatile and light sensor also provides height readouts. Very useful when checking how high you went! You can also set alarms for a wide range of parameters. The sensor works with a wide range of radio equipment.

As Bob says, you are looking at around 1300 watts with that setup. That's what I use for my 70 size Fantasista. You would do better with a Turnigy G160 (if only Hobby King were still able to supply it). This is a direct replacement for a 160 glow and should provide around 2,800 watts off a 10S setup. My 10S packs (2 x 5S as it's cheaper to charge as a 5S in parallel) weigh in at around 1.1 - 1.2 Kg so your Capiche empty weight needs to have that added to it. If you want an ESC with braking - that is adjustable braking rather than on/off, you will be looking at a more expensive ESC, typically a Jeti Spin Pro or Castle Creations stuff. I have total faith in Jeti Spin 99s which have been the go to ESC for F3A flying although they are now being challenged by others. I have to say I'm surprised at your Capiche's weight. I found out after I'd bought my Capiche that the Weston Capiche was a bit porky and that if you wanted to crack 11 lbs then it had to be a kit built one with careful wood selection - which many achieved. As you no doubt know, there is nothing worse than an underpowered aerobatic aircraft! The biggest issue you will have with the Capiche will be cooling the packs. I have the same problem with a Loaded Dice that was converted to electric drive. IC models didn't need to cool something sitting on/near the CG!

Posted by Bruce Collinson on 06/04/2020 20:37:07: Watching with interest Peter. Those long reach spring clamps are not ones I have tripped over before but look useful. Where from please? BTC Sorry Bruce, I've had them for so long that I can't remember where I got them. They are prone to falling apart! That is the yellow pad tends to detach just as you are about to clamp something up! I prefer the ordinary spring clamp that you can see in some of the photos and will no doubt see when I start on the wing!

Thanks Ron.

Ah, you may have a light Capiche. Mine was over the 5 Kg without the Saito! I spoke to the guy who did the flight report on the Weston Capiche 140 and he used a YS 140 in it which is a very powerful motor being supercharged and fuel injected. If yours came in at 4.5 Kg then you were almost 2 Kg less than mine which will make a big difference. I'd still go for a 10 S set up though because this is a 2 mtr class aerobat. In fact it is just over at 2010 mm long. Only 110 size models tend to use 8S packs. Try it by all means but I think you will be wanting in power for good aerobatic performance. For a 10S setup, I'd use a 21 x 13 prop or thereabouts. An 18 x 10 prop is definitely a 110 class prop. That's what I used on a Wind 110 with an 8S setup and that was only just enough grunt.

Hi Ron, welcome to the forum. I'm afraid that no company covers model damage as a result of the pilot flying, or not flying, the model. The BMFA insurance covers damage to your aircraft by a third party. So, if someone steps back onto your aircraft and destroys it then you are covered for that. If it's damaged then that's up to you to decide whether you can repair it and I don't think insurance will cover that but I might be wrong. Your best bet is to ring the BMFA head office (0116-244 0028) and speak to the folks in the office who will be able to give a definitive answer to the point above. What the BMFA insurance covers you for is any damage you cause such as crashing into someone's car, or house or, in the case of the MoD into one of their combat aircraft! That's why the BMFA cover goes up to £25 M! Regards Peter

Adrian, brings back memories of my Capiche 140! They are rather heavier than you would expect. Mine, with a Saito 180 tipped the scales empty at 6.5 Kg. The Saito was just not up to that and vertical lines always ended when the aircraft ran out of puff. I don't know what your Capiche weighs, but if it's like mine, the suggested power train will not do the job. Even a standard F3A power train, 10S with around 2,800 watts will probably struggle with 6.5 Kg to lug around. My current F3A mounts are around 5.1 Kg and use around 2,600 to 2,800 watts peak to fly an FAI schedule where the vertical speed can be maintained constant with respect to the horizontal speed. The vertical performance is unlimited - something that my Saito 180 powered Capiche was woefully short of!

Just to clarify on the hinging of the control surfaces, this is what I am trying to achieve.  The black + marks the hinge point for the control surface. As it happens, the 1/16" square stringers are not really needed so I will not be using them when hinging the rudder and ailerons. Using a bit of scrap, I mocked up what this might look like and checked that it worked OK and that 's the next photo. It all works fine provided that you have properly radiused the control surface LE. As I was to find later, it is best done by trial and error! Isn't it always? So, I then drilled the elevators using my home make centre drilling jig and then shaped the leading edge. The photo below shows one elevator LE shaped and one about to be. Using the long Permagrit sanding block makes the job very easy to achieve. As you will see on the right most hole in the lower elevator, I have cut a clearance slot either side of the hinge pin head. That allows the hinge to operate without fouling the balsa. The next job was to form the tailplane trialing edge to create a hemspherical socket for the elevator to fit into. This proved to be a real pain and that decided me on altering the construction for future control surfaces as I mentioned earlier. So, here's the first elevator in place with the pin hinges dry engaged. They won't get stuck in place till I've covered the Mustang. As you can see, the hinge is pretty close to the full size and a lot closer to scale than the normal V hinge. Finally, here are both the elevators dry connected, the tips sanded to shape (final sanding still required) and the balance tab slots in the tailplane cut out. I will be gluing the balance tabs on in my next session and also sorting out the elevator saddle/horn and dry fit that. That needs to move aft by 1/8" so that it sits on the new hinge line. Edited By Peter Jenkins on 06/04/2020 18:51:46 Edited By Peter Jenkins on 06/04/2020 18:52:41

A carbon tube will certainly be lighter Ron but remember these light weight aerobatic jobs don't like having power on when heading downwards. Build up too much speed and then a quick yank bends the tube! Keep the speed and elevator movement in check and the alloy tube will be fine unless you want to lose a bit of weight.

Well, I finally managed to get some time in the shed today. First of all, I was surprised to see that most of the ribs on the underside of the tailplane seemed to have very little camber. After consulting the plan it was clear that the tailplane was symmetrical so I grabbed a sheet of balsa out of which I'd popped the tailplane ribs and cut some 1/8" strip. I then cut these to size and glued them to the top of the ribs that seemed to have a flat undersurface profile as you can see below. I sanded these to the required section and then cut out the sheet that covered the structure into which the balance tab would fit. I then glued on the previously glued together sheeting. It was only after the glue had set that I remembered I wanted to fit some balsa blocks to drill into for fixing the Robart hinges!!!!! So, after carefully marking where I needed to cut our the sheet, I bit the bullet and cut! The 1/8" Robart pin hinges had arrived just after lunch and proved to be exactly the right size. So, I decided that 3 hinges per elevator would be fine and made up 4 blocks from 1/2" sheet to fit the space. The third hinge block will be the block I glued in to the inboard end of the balance tab cutout. Having got the blocks glued in it now looks like this. Once the glue had dried, I added the last bit of sheeting and clamped it up to dry. While it was drying, I took the time to put the 3 sizes of hinge pin side by side and it quite surprised me how big the difference in size was! The grey one on the left is 3/16", the black one in the middle is the 1/8" one, and the black one on the right is the 3/32" one. Once the glue had dried, I used a razor plane to cut back the LE sheet so that it came level with the LE spar. It now looks like this, although since I've taken the picture, I've put a bit of light weight filler over the 2 cut outs I had to make to get the hinge blocks in! It now looks more like a stabiliser! Tomorrow, I'll glue on the tip blocks, sand the LE to the required shape and figure out how best to sand the rear stab structure so that it has a concave structure as well as shaping the elevator leading edges.