fred clarke

Erfolg Here is an off the wall suggestion that I have used before. Before you start major surgery just put a little bit of UP on both ailerons. This will have the effect of reducing the camber of the wing. I would try something like 1mm on each side and see if that helps. If it does then you could try a little more or less until you get to what is comfortable for you and your style of flying. I suppose the really clever way would be to set this on a switch and then try at height. If this gets you to where you want to be you can then decide to live with it or go for the surgery route. I know that this would also increase drag but I suspect that you would not notice this. I used this on a model where there was no datum to set up the ailerons so I set up as best I could by eye and then 'trimmed' as explained above until I was comfortable with the flight characteristics.

Interesting debate regards AoA etc. However, the original comment was regarding (IIRC) excessive climb rate at full throttle. I have noticed this with a number of elec designs (incl PC) especially since the introduction of brush-less motor/lipo combination especially at the higher power/weight ratios. In short, and once again IMHO, it is not only the AoA of the wing but also the aircraft weight, CG position, tailplane AoA and moment arm, engine power and thrust line (and a lot more, I suspect) that affects the rate of climb (and everything else!!). As there are so many variables it is inevitable that some compromise is required. My approach is to sort out the CG first by tweaking CG position and trims on the glide and then sorting out climb rates/angles by adjusting thrust line. This inevitably is an iterative process. In the worst case scenario (on a powered glider) I have resorted to some down trim mixed in with throttle but even that can cause problems. As far as PC is concerned I have ended up something like 6-7 degs of down thrust to get to the beast to fly comfortably (for me) with the CG as near as makes no difference as per plan. Happy to elaborate if anyone is interested.

Dave re your wings. I would echo Colin's thoughts - it all depends in which direction and how much. Although I am a great fan of the all sheet wing they can be problematic if you go the tissue-dope route. Certainly, using sanding sealer first does help. I have flown a small all sheet model that had about 1/4" wash-in on one wing. The first 30 secs of the first flight were rather troublesome not helped by poor tx mixing (it was tail-less) on my part. However, once trimmed it look very strange on the ground with the amount of control deflection needed to balance out the warp; however, flew fine! Is it time to cut your losses and build another wing and cover in film? Also - re the Phantom. The loss of speed of the RAF to US version was often explained as 'That's what happens when you Spey a bitch, she goes fat in the a**e and slows down!' fred

Re model weights. Mine weighs in at 28 oz primarily because it has a undercarriage - see piccies in my gallery. I am more than happy with how it flies but have not seen another PC to compare it with. Certainly, the speed range is fine by me. fred

Erfolg Is this what you mean: 29/11/2013 20:39:42 Covering - I used solarfilm throughout. Cover the bits (fuselage, booms, wing and tailplane) before gluing together. Just ensure you end up with wood to wood joins by stripping off any film that gets in the way. Certainly not my original idea either - not sure where I got it from - that brain cell died a long time ago. fred

Erfolg My thoughts on the points you have raised in your last 2 messages. Covering - I used solarfilm throughout. Cover the bits (fuselage, booms, wing and tailplane) before gluing together. Just ensure you end up with wood to wood joins by stripping off any film that gets in the way. Servos - I used 2 * 9g servos, simply because they are what I had, both mounted simply using silicon. I now use the 9g metal versions (eg 14g) on my newer aircraft simply because I can't be bothered to get too wound up by the odd few grams weight and the mg ones seem to have less play. I cannot see 5g, 1.5 kg servo causing problems especially if you have 2 of them on ailerons. After all the standard PC will turn the scales at something around 800g. As far as the elevator goes, try this. Build aircraft as complete as possible excluding elevator servo. Rig out in flying condition (eg prop, battery etc etc). Balance on a straight edge and then see how little force is needed at the elevator to get the aircraft to pitch. If you want you could even tack the servo in place with a bit of tape. This is how I eventually sorted out my PC landing gear position. Hope this helps.

A few thoughts on power/weight etc I first tried elec way, way back when very little kit, and even less information (the internet was 15 years away) was available. My first attempt, an MFA kit (can't remember name but has been in Fly Electric column a few months ago), was uninspiring; a successful flight was if I was able to maintain launch height. All was solved, however, by fitting a PAW 2.5 diesel! My first really successful electric was a Simplex (post war free flight) powered by a Graupner Speed 600, 7 cell nicad, 3:1 gearbox and a massive prop. Things improved, slowly, as more and more information filtered out and kit moved from brushed to brushless via cobalt motors; 'speed' control moved from a servo operated micro-switch, via other electronic gizzmos, to esc etc etc etc. The one thing that remained with me, however, was the belief that you can never (well, nearly never) have too much power. After all, that is what the throttle is for. So, especially now that costs have fallen dramatically, I will have more power than quoted for a plan/kit or whatever. My PC works out at around 160 w/lb flat out. However, once happily in the initial climb, throttle back (typically to about 2/3 throttle) and away. Not suggesting this is the only way but it works for me.

Steve Good stuff - always satisfying to get a problem sorted.

Steve Have you got another motor you can try the ESC with. Also, have a very good look at where the 3 motor wires enter the motor to see that the insulation is in good nick and doing its job. A stuttering motor could be caused by one of the wires shorting out on the motor casing or to another one of the wires.

Steve A few more thoughts for you: Assuming that you have the stock motor fitted, the HK website recommends a 20 amp ESC - you have a 25 amp one thus you would seem to have plenty in hand! If the ESC had a fundamental fault then I don't think it would restart. It seems to be shutting down prematurely. One of two things will cause premature shut down of the ESC. Firstly, overheating. It will then enable you to carry on after it has cooled down. Secondly, it has reached low voltage cut out (lvc). Herewith a simple test. Fly until the motor cuts, shut the throttle, count to ten slowly, reopen throttle, If the motor restarts then I would bet on lvc and a duff battery. If it doesn't restart after 10 sec, shut throttle, count to 10 again, open throttle, etc etc. If it is lvc, the battery recovers quite quickly from an lvc but slower from an overtemp. This feature is actually quite handy if the motor cuts at an inopportune moment - close throttle, count and, with a bit of luck, you'll get a few seconds power to help you out. Use this a lot when flying combat. If you do want to buy bits then full steam ahead. Remember the old adage that the ideal number of models/motors/esc/batteries/rxs etc etc etc is one more than you all ready have. Repeat ad infinitum.

Ah, the pleasures of electric flight. FWIW chasing down snags like this on an electric model are an absolute joy! Please don't take this the wrong way but are you sure that the battery has not just simply run down. You seem to have got a 5 min flight; is this reasonable based on your battery size and current draw? A quick run with a watt meter should clear this up. However, the symptoms you have described suggest (and I put it no stronger than that) that something is overheating. This, in turn, leads you suspect that too much current is being drawn for some reason. Alternatively, the battery may not be up to the task. Thus, my approach to a problem like this would be to put a watt meter on the setup and see what current you are drawing and then checking to ensure that you are within the spec of the motor, esc and battery. Also, keep a close eye on the battery voltage to see how that is behaving. If the battery is on the way out you may see the voltage drop to around 9 - 9.5 volts, the motor stops as the low voltage cut out operates and then the battery recovers and you go through the whole cycle again albeit for a shorter time. If you can monitor each cell that will give you an even better picture of what is going on as you may just have a single cell playing up. Also can also monitor the esc and motor temp while doing this. If all seems well with the wattmeter, then discharge the battery and charge on another charger and try that. If that doesn't help I would swap out the battery for a known good one. If that doesn't solve the problem then swap out the esc for a known good one but use the original battery. The last item, IMHO, to suspect is the motor and swapping this out is the last thing to try. If you still get the same symptoms having tried a different battery and esc then I would suspect lack of cooling. Certainly, my experience is first to suspect the battery (even if it is brand new); in my experience they seem to give up the ghost with a whimper rather than a bang assuming they have not been physically damaged. The only problem I have ever had with an ESC (assuming it is still full of magic smoke) is that one particular one would not work properly with one particular motor. The only problem with a motor (other than crash damage) is that I over-propped it and it burnt out (totally avoidable and really, really irritating). I must emphasis the above is what I would do and I do not claim it to be clever or the only way to do things. Its just an approach that I am comfortable with and has worked in the past. With a bit of luck someone else will chip in with a really simple solution and I will use that!!!

On the question of launching ....... I don't need to launch my PC as I have fitted an undercarriage. I know its cheating but I enjoy doing touch and gos. However, I regularly fly and Assassin flying wing and, until its demise, a depron F15. Both of these were launched side arm. Once you have sorted the technique its easy (but then again so is anything!). The biggest problem I had was to learn not to chuck with all your might, as this caused all sorts of problems, but just guide the plane until it almost just flies out of your hand. Certainly, in the early days, a hefty chuck with max power provided entertainment for the spectators. As learning took place, I found that max power with a gentle toss was the way to go. Both of these planes were overpowered compared to the designers intention and once both hands were on the tx then throttling back was usually the first step. Having said that I would be wary of using this to launch my PC as at 28 oz it is on the heavy side. However, for a lighter model without the added drag of an uc it might be worth a go - especially over the near mythical long grass.

Tried and tested and work for me even on larger models: Hinge tape - I use Scotch Magic Tape - any half decent stationers should have this - I get mine from Tesco. Bit like sellotape but semi-opaque.Goggle will give you 481K hits! Sticks well, may have to replace after a few hundred flights!!! Elevator servo - remove any film covering from the tailplane and fin the size of the servo - remove label off servo - clean servo with thinners - stick to tailplane and fin with silicone - clamp until silicone set. Will come off with careful use of scalpel if necessary. Hope this helps.

Bob If your Sharkface was the single channel, goes like hot stuff, from about 40 - 45 years ago then more than likely!!!! I agree with your point re designers preferred way of doing things etc. How many times have you seen models that need sheeting 4.25" wide or 37" long!!! - no-one is going to miss the odd 1/4" or 1" at least not on a sports model. I have the utmost admiration for those who build the vintage style cabin monplanes with the 5 or 6 pieces of wood wing tips - but it is just not my thing; I laminate them!!!! Fred

To pick up the point made by Erfolg about following a plan absolutely. I would agree that following a plan absolutely is not essential providing you are confident that the change is beneficial. Many , many years ago I was told that the secret of good building was to simplicate and add lightness and I try to follow this. So, for example, I only use ply for firewalls and uc mounts. Any other formers that call for ply are replaced by balsa one size up eg replace 1/8 ply by 3/16 balsa. I have replaced the 1mm fuselage doublers on the PC with 1/8 * 1/2 balsa. This means you are gluing the wing onto a 1/4" fuse side rather than a 1/8" + 1mm side. I am not saying there is anything wrong with the plan as drawn it is just the changes I have made made it easier for me to build. Also, a former like F2 can be made out of 4 bits of strip overlapping at the corners rather than from sheet. At the end of the day do what feels right but don't grumble if it all goes to rats suvh as my uc mod!