Greyhead46

Hello Steve Glad you enjoyed the thread! Grahame

As this is the time of year when many of us will be setting up our new models ready for this year’s flying season I thought it worth recounting my experience from last year. Towards the end of last season I was out with my foamie electric glider which I have been flying for a couple of years now using my trusty JR 3810 with FrSky 2.4 rf module, when for no apparent reason it nosed down and ploughed into the ground. Luckily the coincidence of not too much altitude, boggy ground and full up elevate alleviated the worst. Having retrieved the model amid talk of “strange things” happening to models at the Redmarshall field and my own musing over the new electric fence the club have installed to keep the horses on their own side of the fence I returned home to stick the nose back in place. Repairs complete my thoughts turned to what had really happened and my first idea was a dodgy elevator servo but something was bugging me about the model as I’d extracted it from the mud and when I removed the transmitter from its case the penny dropped! Being smart, when I first set up the model, to save having to program dual-rates, exponential and CAR, I changed the name of an existing, no longer used memory bank and checked everything wobbled in the right direction. I just had to reverse the aileron channel, neutralise the trims and was ready to go in no time; simple! What I had failed to remember was that the previous model had been a slope soarer and to help if lift went marginal I had programmed the “landing” switch for a few degrees down flaperon with a smidgen of down elevator to lift the tail. All things being equal operating the switch shouldn’t have been a disaster, but I had reversed the aileron channel so they both deflected up killing all lift from the wing at the same time as applying down elevator. Not so smart after all! When I’d retrieved the model both ailerons were deflected up, at the time I thought they must have been deflected by the force of the arrival but being top hinged with control horns out the bottom surfaces if at all they would have been deflected down and that was what had been bugging me. What exactly happened is pure conjecture but I assume I must have removed my hand from the right stick, to scratch my nose or adjust my hat, who knows? On the return journey my hand inadvertently hit the “landing” switch, which is situated just above the right hand stick, and the rest as they say, is history.

Hello Jerry As I designed my SE5a from scratch I can’t really help with the actual construction, Belair should have sorted all that out for you! The only suggestion I can think of is the addition of thread braces as shown on pages 3 and 4, they add very little weight but add greatly to the stiffness of the rear fuselage and they look good when peering into the cockpit. The finish detailing is a different matter so if there’s any process that I haven’t explained fully just ask and I’ll certainly do my best to clarify. I knew exactly what I’d done but trying to explain it is never easy. Grahame

Hello Paul I suppose so but I really think aeroplanes, be they model or full size (Vulcan!) belong in the air! Grahame

Thanks for the replies. Paul: The offer to buy came “out of the blue”, I hadn’t advertised or anything, it was a post on the original build thread so I assumed it must have come from a modeller but later, after it had arrived in South Africa, I got another post asking where the propeller was (didn’t seem to realise it needed an engine) so I don’t know? Basil: There’s nothing too hard about it, I just break the build down into sections, if you do the best you can with each section you’ll have a model you can be proud of! The more you do the easier it gets so just keep building, you’ll get there. David: I don’t think I’ll be doing another thread, both the Elf and the SE5a were built some years ago and arthritis means my hands just don’t work very well now. Grahame

Hello Murat Thanks for the reply. It's always a testing time (no pun intended!) the first few times with a new model until things get trimmed but the satisfaction level when a model you've built, and more so if it's your own design is way up there. Grahame I suppose it had to happen; after 4 years of trouble free flying the Elf bit back today; of course it wasn’t the Elf’s fault it was mine! It was one of those very rare days, really hot and a flat calm. The first flight was uneventful apart from a rather fast landing, which inevitably ended with the model on its nose; it’s amazing how much even a slight breeze slows the landing approach. After watching a few other models flying I prepared for the next flight. By this time the windsock was behaving rather oddly, there was still no wind as such but every now and they the air “moved” and this movement was in random directions; could it have been caused by thermal activity? I should have known better and changed to flying the ArcoWot, but the other models had had no problems; I opened the throttle but half way down the strip the Elf lifted a wing and cart wheeled along the ground. It looked a sorry sight; one wheel bent up at 45º, one set of wings at very strange angles and warren girders sticking out every which way. I picked up the bits and did what I should have done earlier; I carried on flying with the AcroWot. Having got the model home and had a chance to have a good look at it I can safely say it’s not as bad as it first appeared. Most of the bolts holding the Warren girders and cabane struts on one side of the model have sheared but having replaced them temporarily with twists of wire the wings are once again aligned correctly and they fold with no trouble. The axle bent back into position easily, the only real damage is to the rear of the fuselage just in front of the tail plane where some of the sheeting has split, this is not a structural part so it will be easily fixed with a drop of cyano. I think I really got off lightly, although replacing all those bolts is going to be a tedious job. The Elf is ready to fly again but we’ve got those strong winds back again, most frustrating! I found one more thing that was broken, the cockpit bulkhead, which holds the compass and a couple of switches. It’s not a structural part of the fuselage, it’s only for scale detail and will be quite awkward to replace so I’ve deferred that job for now. Replacing the 14BA nuts and bolts went a lot easier than I thought it would from my experience of doing the job originally. What made the difference this time was that I had fitted the Warren girders in place temporarily with thin wire. The Warren girders are the only things holding the wings in the correct positions relative to each other. The first time I did the job I fitted one Warren girder, then the next and so on, this meant that the wings tended to move about as I worked on them making life rather (very!!) difficult. This time I locked the wings in position with the carbon fibre “tongues”, removed one Warren girder at a time, which left 5 still holding the wings, fitted this one with the 14BA nuts and bolts and then removed the next. Whilst still not the easiest of jobs it was a lot better and is a lesson learned for the future. The End of an Era After giving me much pleasure over many years, both building and flying, the Elf is now on its way to a new home, in South Africa! Deciding whether or not to sell the model was not an easy task as she really is a “one off”. The offer came just as we had sold our house and storage was a real issue, some things just had to go and of course I’ve now got the SE5a to play with. It was a toss-up between the Elf and the wife but the thought of eating beans on toast for the rest of my life swayed me towards parting with the Elf and in all honesty I don’t think I’d have got as much for the wife!

Hello Manish I have to agree with you, a scale model flown in a scale manner to me is the pinnacle of aeromodelling. It may not be as eye-catching as the 3D fliers but it takes a lot of practice and to be honest the "banking right" photo above is about as aerobatic as it gets! Grahame When I started the Laser at the “photo shoot” it was quite noisy but having travelled 160 miles to get to the flying site there was no way a bit of noise was going to stop the flying! During the session the noise level gradually increased and on the 4th start exhaust fumes started to exit via the cockpit; those of you who have followed this thread may recall that I made a remote silencer that up to date had performed very well but something was obviously amiss. The exhaust system consists of about 6” of stainless steel flexible pipe connected to the silencer by a short length of silicone tube reinforced by braided stainless steel. The silicone tube has completely failed, I assume the missing bits must have been blown out through the silencer. The hot exhaust gasses eventually burned a hole right through the firewall, hence the fumes from the cockpit Both aerobatic and funfly models use these silicone tubes extensively to join the exhaust to the “tuned” pipe but not enclosed inside a cowl; the reduced airflow and the resulting increase in temperature obviously proved decisive. A re-design of the exhaust system is called for and a fair amount of repair work to the firewall so no flying for a while (with the Elf at least) but it could have been much worse, just behind the firewall there are a lot of wires for the radio equipment and of course the fuel tank; the Elf could have come to a spectacular end! The damage is not as bad as I’d first feared, what I thought was completely degraded wood turned out to be the remains of the anti-vibration foam. Yes there is a hole through the firewall (an appropriate name as it happens!!) but the main structure is still sound. There is some delaminating of the ply but having removed all the charcoal and giving it a thorough soaking with super-thin cyano it’s now as strong as ever. The only thing inside the fuselage is a bit of scorching of the wood and the insulation on the power lead has turned brittle. Luckily it’s not the battery lead itself but the switch harness lead so that’s easy and cheap to replace. This repair shouldn’t take long, just a case of gluing a patch on both sides, but figuring out what to do with the exhaust system to stop this happening again may take a bit longer! Modifying is nearly always more difficult than starting from scratch, in this case the silencer inlet and the flexible exhaust are slightly different diameters; this wasn’t a problem when they were joined by silicone tube but I’ve had to use 3 different diameter tubes to join everything together. As it is impossible to fit the exhaust as a complete unit it has to stay as 2 pieces, once again not a problem when they were joined by silicone tube. The “moveable” joint is a reasonably tight fit and has been sealed with car exhaust paste. On the test runs it’s sealed OK and I can now say that the exhaust works very well and there are no signs of the paintwork failing around the undercarriage.

Well it’s took some time but at last I managed to get myself, photographer and weather all to co-operate so here are a few flying shots. Hope you think it’s been worth the wait! Take off Banking right Straight and level Over the top On finals and a "fuzzy” shot of touchdown; it was just too far away from the camera! But things didn’t all go according to plan!

There wasn’t much left of the flying season but the Elf had a few more flights before being packed away. After the winter recess, I got the Elf out for it’s pre-flight checks. Of course the Laser fired up “first flick” and ran faultlessly but there were a couple of things to sort out, both involving 2mm nuts! When I checked the nut on the tail incidence adjuster it stripped the thread with only slight torque on the spanner. The tail is mounted on brackets made from thin steel and attached via ball joints to allow for the fact that the brackets are fitted to the tapering fuselage sides. The closed loop for the rudder goes in the space between the fuselage and the tail plane. The adjuster consists of a 2mm rod threaded at both ends with a nut soldered at one end. The rear of the fuselage has a dowel, with a length of snake inner down the centre, into which the adjuster is screwed in or out to alter the tail incidence. A lock nut goes the other side of the rear tail brace to keep things solid. The braces are attached to the tail and fuselage by steel brackets again using closed loop adaptors and 14BA nuts and bolts. There is very little movement at the fixing points as the tail incidence is altered and the bolts don’t need to be slackened. In this shot you get a good view of the tailskid, made using epoxy and carbon fibre in a plasticine mould It was actually the rod that had stripped; it was one of the 2mm rods from the model shop with a thread at one end. I needed a short rod; about 50mm long, with a thread at both ends so I’d tapped the extra thread. When I investigated the problem I found that the rod as supplied has a “rolled” 2mm thread but the rod itself is only 1.7mm diameter. All had seemed OK when it was made but obviously with vibration from the engine and the load when elevator is used, the undersized thread wasn’t good enough for the job. The other thing is the aileron control arms; these originally used a 2mm nut and a closed loop adaptor. Nuts are intended to be locked, either against another nut or some hard surface, but in this instance I’d used the nuts as a bearing and vibration etc. has caused considerable wear. I’ve replaced the nut with a length of snake inner cyanoed into the tube and then tapped 2mm for the closed loop adaptor. I was a little worried relying solely on glue to hold the tube and snake together but when testing the result it was impossible to pull the closed loop adaptor out of the tube. At least I found the problems before anything disastrous happened and it re-enforces the need for regular checks.

This is it, the weathers OK and the time is right, so pack up the car and head for the field. When I arrived the steady breeze had dropped to an almost flat calm, still this is better than going the other way. First things first, a few photos just in case the worst happens, here’s one on the starting box and table….. ….and in the background of this photo the club aerobatic expert Bob Wasson is preparing his aerobatic model. One problem I’ve had with all my previous “early” biplanes is their tendency to ground loop i.e. they veer off course when taking off, as it’s important to take off and land directly into wind with these models this results in a lot of aborted take offs. The problem can be rectified by widening the under carriage and moving the wheels forwards but then it’s not a scale model is it? I’ve found what I think is the perfect answer, a “heading hold” gyro to control the rudder. With the model pointing into wind the gyro is activated, via a spare Tx channel, and so long as you can resist the temptation and keep your hands off the rudder stick the model will track straight down the runway. A couple more photos before the "moment of truth" With the engine nicely warmed up a couple of runs to check the ground handling; no problems, straight as a die, but then it would be, the gyro’s doing all the work not me! Gradually build up the speed to see if the rear folding sections of the lower wings stay in place over the bumps and she’s nearly airborne, close the throttle and everything’s fine so the next one is for real. This time a bit more throttle to ensure we reach flying speed and away she goes, as soon as the wheels leave the ground the left wing drops and it needs full right aileron just to keep level. Too late now to abort so gain height and see what we can do. A few clicks of right rudder eases the problem but when the throttle is closed a sudden right turn, it’s obvious that landing is going to be quite a challenge so I decided to cruise around at a safe height to let the nerves settle. Gradually reducing throttle and adjusting rudder trim line up for a landing, got to get this right as any sudden throttle change will result in an equally sudden turn! More by luck then judgement I hit the square and she’s down in one piece. Time for the post mortem. First the ailerons are virtually useless so must use CAR (coupled aileron rudder). The trim changes with throttle indicate the need for more engine right thrust. Bob gave the model the “once over” and declared that there was in fact slight left thrust (note this is an expert not an “expert”!!) and he suggested I adjust the thrust line to 2º right thrust. At home careful measurements proved he was correct about the left thrust and I duly modified the bearers; could only get about 1½º right because of lack of room under the cowl. So how did this fundament error occur? The only explanation I can come up with is that although I altered the construction of the fuselage nose section completely to accommodate the non-standard Laser engine bearers I used the original “F2” as a starting point, at some point during the tracing, altering and re-tracing onto the ply I must have turned the paper over so instead of the rear of the bearers being offset to the left they were offset to the right. I mixed CAR and tried again a couple of weeks later, what a difference, the model was now completely controllable but still turned left as the throttle was opened, if I’d managed to get the full 2º as suggested I’m sure it would have “flown on rails”. I now also mix in a small amount of right rudder with throttle and she flies like a “good un”. A wonderful sight on a low, slow pass with the Laser burbling away at ¼ throttle, it doesn’t get much better than this!

One thing I have mentioned earlier in reply to Manish is the spinner. The shape on earlier planes is not like most of our plastic spinners that are more akin to the WW2 period. The required profile can be approximated by using just the front section of a standard two part plastic spinner. The rear section, that usually covers the prop, can have the flange removed or be discarded and a back plate made from aluminium. The front section then has to have cut outs to fit the prop and the screw support pillars will probably need reducing to clear the prop hub. One problem I’ve not managed to solve is the aluminium finish; the electric starter soon makes a ring on the spinner. The best I’ve come up with so far is a coat of silver paint covered with a skin of epoxy resin, this lasts a few starts at least. I know the easy answer is to flick start the engine, but as I suffer from tennis elbow, strange that as I’ve never played a serious game of tennis in my life, it isn’t practical in my case! Now comes the worst bit of any build! You’ve spent what feels like a goodly proportion of your adult life building this model, the radio and engine are fitted and working a treat and now you have to DO NOTHING!! Just sit and twiddle your thumbs as you wait for perfect weather, a nice warm, steady breeze to help keep the landing speed reasonable. I can’t understand people who, after investing all the time and effort into building a scale model, test fly it in blustery conditions; apart from the obvious higher risk of damage it is very difficult to make meaningful trim changes. I place another restriction on myself for a maiden flight; I don’t try when the site is busy. I feel enough pressure without numerous eyes watching your every move and /or a crowded sky. The worst culprit is the club “expert” who will point out all the things where you’ve gone wrong and explains at length how he’s solved the problems. Talking of the club “expert” prompts me to ask 2 questions: 1 Does every club have one or are we just “lucky”? 2 Has anyone actually seen any of the multitude of models he professes to own, not to say having seen him fly anything? The next post will chronicle the first traumatic flight and the subsequent changes which, made over a few flights, have transformed the Elf from a “dog” to a “pussy cat”!

Where to hide the switch etc. is always a challenge! But if there’s a convenient hatch why no use it? This hides the switch and the remote glow. My home made hinges proved not to be up to the job at this small size i.e. only 3 section to each hinge so had to be replaced. The easiest way was to use thin rubber strip. The engine compartment is rather more crowded then I’d first envisaged, the nose section is tapered in plan, side and front elevations. The standard silencer just wouldn’t fit so I decided to just use a flexy pipe, about 6" long, attached to the scale outlet. Having talked to other Laser owners we thought that this would give sufficient silencing. The bent pipe is for the crankcase breather, saves having an extra hole in the under pan and blasts the oily mess away from the fuselage. This system worked well, up to a point! Laser engines normally sound very realistic and although it wasn’t excessively noisy, to me it sounded a lot more like a single cylinder. Without any expansion chamber the exhaust is hotter, I’m sure we’ve all suffered from “frozen finger” when operating spray cans for a prolonged time, as gasses expand they lose heat. The hot exhaust mixed with the breather output may explain the paint problems as it is directed onto the undercarriage. I’ve now made a remote silencer from brass sheet. I used silicone tube to join to the flexible pipe. (Turned out not to be a good idea!). The engine with this, is certainly a lot quieter, I think more so than with the standard silencer, I just hope that it cools the exhaust sufficiently and that the engine noise is back to it’s original realistic self!

Hello Solly and Manish Thanks for the replies. Personally I've never had any issues with Tufcote lifting but I use "straight" fuel, I find Lasers run perfectly well without any nitro. Grahame It’s now time to fit the radio gear. One problem with closed loop or pull / pull systems is “hiding” the cables as they pass through the cockpit, one solution is to use a snake from the servo to a bell crank fitted behind the cockpit to which the cables are attached but in this case I decided to fit the rudder and elevator servos in the luggage compartment; it also makes them easy to get at to adjust. No worries about ending up tail heavy with a large lump of Laser up front. First a shot with the hatch closed; you can see that the fuselage is clearly made of wood as the grain is still slightly visible as it is on the full size and you can see one of the magnets which hold the lower rear wing section in position. Now with the hatch open, once again a magnet is used to hold it shut. The aileron servos are mounted to the fuselage side with the arms protruding through slots to attach to the push rods and a mini servo under the cowl operates the throttle. The throttle linkage caused some headaches, with the carburettor angled it wasn’t an easy job until I thought of the idea of making the linkage run back into the fuselage first. The Bowden cable loops around the fuel tank and then back into the engine compartment, a bit messy but it works. The bolt through the firewall is one of a pair, the other one in a similar place on the other side of the fuselage, which will carry the current for the remote glow (yet to be fitted). They also help secure the firewall as they go through brackets bolted to ply fuselage doublers (see photo in post 1, the "heart" of the model).

That’s the construction finished. Now for the finishing. All the wood parts are given at least one coat of clear dope and one of sanding sealer, this fills most of the grain but the finished surface is still obviously wood, parts that represent metal receive 3 or 4 coats of sanding sealer. Lithoplate is left as it is, make sure it is well degreased after annealing to get rid of all that soap. Any “metal” made from printer paper, in this case the cowl side panels, get a coat of dope followed by a thinned coat of silver Solalac. Matching colours is very difficult, even when you’ve taken your own photographs there seems to be many different shades. Using Photoshop I “sampled” several different parts from different photos and averaged the results. Armed with this information I had the colours mixed by an automotive paint supplier, not cellulose but brushing enamel as I don’t like spraying. I always use matt paint as I find it covers a lot better, for a gloss finish just use gloss fuel proofer. A thinned coat first as primer/undercoat then as few full strength topcoats as you can get away with to save weight. To be accurate the Elf should not be weathered much, as it is a museum piece and only flys on high days and holidays, but I like my models to look like the real thing and besides weathering is such good fun. Leave the paint to really cure then rub gently with 1200 wet and dry using plenty of soapy water; rivet heads, panel edges and corners show first and with a bit more work worn areas around steps and cockpit edges come to life, brilliant! The photos of the cowl earlier in this thread show the results of the weathering and in fact I like to include the odd dent and scratch to add to the “realism”. I decided to use satin polyurethane varnish as a fuel proofer as it is recommended in all the model mags. This has proved to be a disaster as after only a few flights the paint, especially on the undercarriage and around the exhaust, started to lift. Re-painting is now complete and I’ll be giving the entire model a covering of matt Tuffcoat. The moral of the story is “if you’re going to try something new don’t do it on a model that’s taken nearly 3 years to build!!”

The Warren Girders were made in a similar fashion to the cabane struts except that the snake inner this time is clad with spruce and 1/16th ply. The cross wires are made from 22swg piano wire and to avoid metal-to-metal interference they must be either insulated from each other or permanently joined. I decided to go the latter route so made small tinplate discs and formed a groove along the diameter for the wire to sit in. First one disc was held in place at the crossover point underneath the lower wire sandwiched between a piece of 1/16th balsa clamped to the wire and the wire itself then soldered, another pre-tinned disc was placed on top of the top wire and soldered to the lower disc.