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Showing content with the highest reputation since 30/03/12 in F5J Articles Events and Reports

  1. Homebuilt F5J Soarer (Kevin Beale & Colin Paddon) After a long gestation period, we are pleased to announce the birth of a rare beast … a competition homebuilt 3.8m F5J soarer! When the F5J class came into being, it shone out as a great opportunity to once again be able to produce a homebuilt model which would be able to compete well against the superb moulded manufacturers offerings. With no F3J launch stress to consider, Kevin Beale & I (Colin Paddon) decided this was a totally feasible option albeit one that to date had not been taken up by many other F5J competition pilots, at least here in the UK. So we decided that together we would design and build our own “Medium Tech Composite” 3.8m F5J Soarer. To be able to do this would however require that we master some new building skills and techniques and that turned out to be more involved than we originally thought! We weren’t however starting from scratch as Kevin had a lot of experience in producing moulded fuselages and ditto myself in producing foam wings. It did require though a lot of time and effort in pulling together the requisite moulds, building the automated foam wing cutter, many jigs/templates, vacuum pump rig etc. On top of that many tests were undertaken to understand/achieve the best utilization of materials and hone the required composite skills/techniques of which there were many. It was decided from the outset that if cost effective commercially made components were readily available then we would use them. In our case this meant that we bought the carbon fuselage pod boom and the protruded 10x1mm carbon wing spars and wing joiners. Everything else is self-built. The first thing we needed to do was to hone down a general design brief. After some discussion we ended up with the following: 3.8m wingspan Medium Tech composite construction Vacuum Bagged wings, tailplane elevator/Fin Rudder coupled to a composite fuz pod and boom. Total AU finished flying weight of between 1.4 -1.7kg Proper ballasting capability Good working space within the fuz pod Wide performance envelope to cope with different weather conditions Light enough to be able to use a direct drive motor if required Kevin was tasked to come up with the wing plan-form/ spar layout and I think the finished wing shape is very nice. The fuz pod design/implementation works well and his moulding technique improves incrementally with each one he produces. Again many different lay-ups have been tried out to see what works best. An airfoil section was chosen that would provide good all round performance. We decided to try out various alternatives of tail end layouts including all flying tailplanes through to separate tailplanes/elevators both on the fin, in front of the fin and under the fin/rudder. It came down to personal preference in the end but a fixed tailplane with a separate elevator regardless of layout proved to be our preferred type. The fin/rudder on the version shown here is completely removable from the boom itself to aid transport (i.e. to get it to fit in the transport box) and also to provide access to the tailplane/rudder servo’s. Whilst the finish on the wing is acceptable, with the further testing on surface finish we have now done, we are reasonably confident that we will be able to obtain an excellent paint/surface finish. For his first full prototype, Kevin has gone for the under the wing Elevator/Rudder servo set-up and increased the tip dihedral slightly as we felt Prototype No1 may have been slightly less than optimal although the initial flight tests have proven this may well not to be the case. (see photo of Kevin’s plane in garage) The first completed full prototype is the version you see here and despite several mishaps/mistakes during construction with the worst being when the vacuum pump decided to go open circuit over-night and pulled massive vacuum pressure rather than the 15-18Hg it was set to, it still turned out to be relatively OK though. (I can now vouch for the compressive strength of pink/peach foam although it did mean that the spars on the centre panel were a little proud! Another mistake occurred in the painting of the mylers in as much as we didn’t extend the black far enough along to cover the servo well reinforcements on the tips. As it was only a prototype though, it didn’t really matter. We tested four different types of paint on different weights of glass to see which provided the best release/finish. Halfords spray gloss black turned out to be the best for the black with fluorescent tree marking spray being best for the fluro Orange as it did not require a backing coat of white to achieve the bright fluro result required, i.e. lighter. The wing control surfaces are all hinged with silicon as is the tailplane/ elevator. You wouldn’t think there is much to do to get silicon hinging right but again the right silicon coupled with using the right application technique & custom spreader tool took a while to nail down along with yet mini samples to get it 100% right. This first completed PROGLIDE prototype seen here weighs 1460g ready to fly which for a first prototype isn’t too shabby. It uses a direct drive 28mm diameter outrunner motor turning a 11x7” Aeronaut folding Prop, 40 Amp ESC and a 3S 1300Mah Lipo. The gadget with the two green LED’s is a home built Ubec/ESC BEC change over unit. (If one of the BEC’s fails the other takes over automatically). How does it fly? Well we only managed to fly it twice before it poured down but so far we think it fulfils the design brief nicely. We are extremely pleased with its handling/flying performance but the true test of how good a plane is, comes when its flown in competition against other planes. The feeling of achievement derived from designing and building our own competition models once again is amazing. Yes, the journey involved a steep learning curve with many ups and downs along the way, but if we can do it so can others. Knowing what we now know, we are confident we can get the overall AU flying weight down to around 1250-1300g if required. For UK flying this is really not required but with mainland Europe in mind, an ultra-lightweight model at 3.8m will be worth having in the quiver. The next PROGLIDE versions will be laid up to achieve an AUW of around 1700-1750g ready to fly. We now plan to continue to refine and further develop the PROGLIDE series along with our composite building skills. Hopefully this article might provide the inspiration for others to try similar projects. Kevin Beale/Colin Paddon
    10 points
  2. It's been over a year since I (Colin Paddon) and Kevin Beale first posted details of our home built and designed 3.8m composite F5J glider, PROGLIDE. This update brings us up to date with the project. It’s all very well designing and building your own competition plane but its not worth a lot if it turns out to be lacking in performance compared to the professionally manufactured gliders that it will be flying against. There seems to be a general misconception that home built F5J competition gliders are in some way inferior to the professional commercial offerings in terms of their flying performance. Straight away lets dispel this myth. The prototype PROGLIDE in its first full year of competition use won three UK F5J league competitions and finished 2nd in the 2016 National UK F5J league with an overall score of 99.06%. Myth dispelled. The only downside of designing and producing your own composite F5J plane is the time and effort it takes to do. If we paid ourselves 50p per hour for all the time we have put into this project we still wouldn’t be able to afford to buy them! It’s a complete labour of love in every way but the sense of achievement makes it all worthwhile. A quick look at the web gallery that accompanies this article will give you some idea of the time and effort that has gone into achieving our original goal which was that it must be economical to build, use techniques that anyone with reasonable building skills can learn/do and most importantly have as good a flight performance as the commercial offerings. Achieving the 100% perfect finish compared to the hollow moulded professionally produced planes was not a high priority. We were only interested in its flight performance and were happy to accept a good finish as opposed to a perfect one. During the development period we worked in parallel on different areas of design/construction. For example I decided that I wanted to be able to split the fuselage in half for ease of air transport which meant that the elevator and rudder servo’s were both enclosed within the tailplane mount pod with the boom being secured to the Fuselage Pod spigot by two carbon tubes that could be removed and the boom slid off. Ditto the fin/rudder assembly. Kevin worked on optimising his layout with the servos under the wing at first followed later by the elevator servo in the tailplane pod and the rudder servo under the wing. For his Fin/Rudder he went along a similar route that the Nan Xplorers use. Finding easy to do home build solutions to problems took time, effort and testing. One of the things that several people asked us about was how we made the wing joiners. In the end it was so simple that I wondered why I hadn’t thought of it before. Buy yourself from HobbyKing a protruded 10x10mm square section carbon rod which comes with a 8mm dia hole all the way through it. Cut into required joiner lengths and angle the two inner end faces to the required angle. Roll up 40mm of unicarbon tows to achieve a tight fit inside the hole, wet out fully with epoxy and slide it half way into one half of the joiner and then the other. Put balsa caps down the hole so that it just very slightly compresses the central wet unicarbon and keeps them centrally located within the length of the joiner and then clamp into required position and allow to set. Result, pair of carbon joiners that weigh 23g total. The plane would be destroyed before the wing joiners broke. This technique wouldn’t be strong enough for F3J planes but more than adequate for our lesser stressed F5J models. Quick, cheap and foolproof with the ability to create any angle of joiners you require. Kevin went a different route by using straight solid round carbon rod which allowed him in our normal wing section to get the required dihedral tip angle he wanted. All this problem solving sounds as if it was a PITA, and at times it felt that way, but in reality we both enjoyed finding home build solutions to these challenges. The first two Proglide’s produced used cheap fibreglass cloth on the flying surfaces which enabled us to learn the required composite skills knowing that when it goes wrong (it will BTW!) that it hadn’t cost the earth in materials. However, the aim was always to eventually use Carboline which is a fantastic cloth but it’s not without good reason that it’s called “Black Gold”, its very expensive but gives a strength to weight ratio that is unbeatable for our purpose. The early fibreglass skinned versions of PROGLIDE achieved RTF weights of between 1450-1580g, ie still reasonably light for a full house 3.8m electric plane. With each new plane we tried different lay-up’s, build techniques and incorporated various detail design changes along the way. Lots of time was expended in producing test pieces during this period to prove the viability of what we were doing. We had failures along the way on pieces that we felt sure would work well but turned out not to be of the standard we were seeking. Amongst the various failures though we managed to have some light bulb moments which were always welcomed! One such moment came when we started to investigate how to achieve repeatable 100% success with shaped inflation bladders in the moulding of the fuselage pod in order to minimise the weight. After quite a few failures it turned out that a fine tipped soldering iron and Recycled black rubbish bags (yes really) worked brilliantly. The variable air pressure for this task was handled by a £50 EBay airbrush compressor which had a small air reservoir tank. After trying various layups, like most of the professional manufacturers, we have now settled on using all carbon for the fuse pods. Another light bulb moment came in regard to hinging the flying surfaces. At first we used silicon hinges which did work but were relatively heavy and difficult to get perfect every time. We later moved to using Diamond tape for the hinge along with Microfibre tape on the inner faces of the foam. (Microfibre tape sticks like the proverbial to raw pink foam). This resulted in strong, lightweight quick to apply, field serviceable (if required) hinges that were very free in their movement. They have turned out to be every bit as good as silicon hinges and in many respects far better. After building a few Proglides we felt confident enough to move onto using Carboline. We also decided at this point that we would again take advantage of having two of us involved. Kevin’s first Carboline PROGLIDE was to use our normal wing section whilst mine was going to use one of the new F5J Syner ultra-thin wing sections. We had hoped to use a friend’s CNC foam cutter for this new prototype wing but unfortunately he moved house just at the wrong time and we all know how much time they take up to get sorted out. So, yet more wing /spar templates to make! Using such a thin wing section on a 3.8m wing brought with it a host of new structural problems to overcome and additionally neither of us was totally convinced that these Ultra-Thin wing sections were the right way to go for F5J. Kevin progressed quickly on his first Carboline build as we now knew exactly how and what to do. He made no attempt to get this plane down to be a super lightweight and used standard sized servo’s with a heavy motor/ESC/battery in the fit out. Even so the finished RTF weight came in at just under 1440g. He estimated that had he used lightweight equipment the finished RTF weight would have been easily under 1300g. The project was moving in the right direction. After flying it Kevin liked his PROGLIDE so much that he immediately decided to press on and make a full on lightweight Carboline version. This ultra lightweight PROGLIDE, which he seemed to put together in record time, came in at 1280g. It fly’s superbly. Meanwhile, it took me a while to iron out the new structural issues raised when building a 3.8m solid core ultra-lightweight thin section wing. Eventually though we were ready to proceed with the build. Did it go smoothly, of course not! Due to a stupid error on my part during the bagging up of the centre panel, I managed to ruin the entire panel. It was an expensive and time consuming mistake to make. After the required amount of San Miguel I decided to build a new centre section straight away. I took this “opportunity” to try a different approach with the spar structure. The rest of the build thankfully went without a hitch. The plane RTF came in at 1245g using lightweight radio gear, 1000mah 3S Hv Lipo and a 85g direct drive motor. All that was needed now was to test fly it to see if it performed as well as we hoped it would. Following several test flying sessions we can report that its flight performance has exceeded all expectations. All preconceived negative thoughts on whether ultra-thin wing sections would work well for F5J have been dispelled. In light of the successful flight testing of the first thin wing PROGLIDE we have decided to build a heavier windy weather version using the same thin wing section. In the meantime the Carboline Ultra light just tested can be ballasted to 1550g AUW which hopefully will be capable of handling a decent amount of wind (yet to be tested). But as we all know, here in the UK there’s times when you just need a heavy plane. For those that are interested in weights here they are. table.tableizer-table { font-size: 12px; border: 1px solid #CCC; font-family: Verdana, Geneva, sans-serif; } .tableizer-table td { padding: 4px; margin: 3px; border: 1px solid #CCC; } .tableizer-table th { background-color: #104E8B; color: #FFF; font-weight: bold; padding: 10px; } Part Finished Weight With Gear Installed Weight Carbon Fuse Pod 89g 135g Boom & Tailplane Mount 35g 55g Centre Panel 263g 333g Left Wing Tip 128g 150g Right Wing Tip 130g 152g Elevator 33g 35g Fin/Rudder/Tube 24g 24g Prop/Spinner/Motor 113g ESC 50g Other installed equipment 78g Total AU RTF Weight 1245g In terms of airframe material costs, the fibreglass skinned versions come in at around £100-£130 and Carboline versions at £200-£250. Labour cost….well let’s not go there! Overall, somewhat cheaper for an equivalent commercially produced 3.8m F5J model at this kind of weight! So what next? We are confident that we can further reduce the overall weight with minor detail changes, improved lay-ups etc, but recognise that we are getting close to what can realistically be achieved in this regard with home building. A picture really does say a thousand words, so if you are interested in seeing how the PROGLIDE is constructed, the photo web gallery that accompanies this write up shows all. If you have any specific questions about the plane or its construction please feel free to ask on this thread. Colin Paddon/Kevin Beale
    4 points
  3. In response to the call for some new website content here’s an update on what’s been happening development wise with the PROGLIDE since the last update (March 2017). Short answer, quite a lot! There has now been sufficient time and competitions since the last update to categorically be able to say that the PROGLIDE has shown itself to be a thoroughbred F5J design. I’m not going to list (boring for most people) the many comp successes Kevin and I have achieved with the PROGLIDE other than suffice to say there’s been quite a few of them. Kevin up till now has continued to champion our original wing section whilst I use only the thin winged Synergy section. Both versions have though shown themselves to be excellent performers. We have however found that the Synergy section version offers some advantages over the original wing section in that it hangs in there just as well but shows better penetration in the wind. So what have we been up to over the past year and a half? Firstly we decided that we would like to slim down the fuselage pod to make it more streamlined in its appearance and have a little less air resistance/drag but to still have enough internal space to get everything in without any shoehorning. The attached pictures clearly show just how much its been slimmed down far better than any words can. Kevin, the teams master mould maker, set to work making a new plug followed by new moulds. He did a great job as the pictures show. The other major item we both felt the design would benefit from going forward was to have the ability to produce our own custom sized/lay-ups booms. Whist the commercial versions we have been using certainly did the job they were a tad too lightweight and the size at the tail end was not optimum. After watching a bunch of Youtube videos on the best way for the home builder to make booms we went the opposite way and decided to mould the booms! I had an old Fendon fibreglass boom from way back that just happened to be the ideal size for our new fuselage pod and Kevin used this to make the new boom mould. Unfortunately I forgot to take any pics of the new boom moulds but will do so when I next use them. I had pretty much got on top of producing the carbon fuselage pods to a good standard and right from the first pull the new pods worked out really well. It was a lot stronger and less “Squidgy” under the wing than the original version it was replacing and at 88g AUW, it was light. Next up was the new booms. I had no idea what layup would provide the required rigidity/strength and weight we were looking for. At first I thought the easy way would be to do simple short sections of boom with different layups to determine this. This didn’t work out as I later realised of course that you needed the entire length of the boom in order to test the lateral flex was rigid enough. So no option other than to do various full size test lay-up’s to determine what worked. Home composite building is all about testing , getting it wrong followed by more testing! Laying the booms up in long thin moulds is no easy task to get it spot on and I am still working on the best way to achieve 100% results 100% of the time. Having said that even the first boom out of the mould with a little post production repair work, was totally usable and at 45g not too bad. Its overall strength/rigidity is significantly better than the commercial versions we had been using but it did weigh 9g more. Kevin in fact has used this first boom on his latest model, the PROGLIDE EXTREME. (More on this later). After four complete boom test/lay-ups our preferred lay-up was defined. (Outer - 40g Carboline, Middle-200g UniCarbon, Inner 120g R&G Fibreglass) Final weight of the booms with this lay-up was 41g. Hopefully the weight will continue to come down with more practice. Making the bladders for the booms turned out to be a PITA compared to the fuselage pod bladders, so I’m investigating alternatives for this. We are often asked what pressure we use with our bladders. It surprises a lot of people when they are told it’s between 6-9 psi. The variable air pressure for this task is handled by a £50 EBay airbrush compressor which has a small air reservoir tank. You would be amazed at how much epoxy is expelled from the moulds even at this relatively low psi! I’m sure you’d be able to expel a little more epoxy with a higher psi but its not required for home building as the pics show. Next up was a complete re-work of the spar structure for the centre panel to try and limit wing flex particularly with the thin Synergy sectioned wing. It was decided to completely re-design the spar structure and how it was made. It’s now produced completely outside of the wing and then dropped into a full span channel that is cut from the underside of the wing that finishes 2mm from the top surface of the wing. This has the added benefit that the top surface of the wing requires no additional finishing and gives a perfect top surface ready for lay-up/bagging. Only the underside of the wing where the spar channel is requires minor filling/sanding. The spar uses the protruded commercial 0.5 x 10mm carbon strip top and bottom with solid foam in-between which is then completely wrapped in carbon sock. At the centre of the wing the spars have a substantial moulded carbon dihedral brace that extends out approx 125mm each side. This is made using a simple right angled Aluminium mould. The pics again show it better than words do. I do my spars in two bits and then join the centre panel with the dihedral brace but Kevin makes the entire spar assembly in one piece and drops it into the entire wing centre section in one go. Both methods work fine. Joiner boxes at the ends of the centre section are made by using carbon sock moulded over a 10 x 10mm Ali square tube. Two complete wraps of greaseproof paper are first put around the Ali before the carbon sock is slid on, stretched out and epoxy applied. The greaseproof paper must extend past the ends of the sock by 50mm to ensure no epoxy creeps under it. The greaseproof paper also provides the working clearance fit for the joiners. This technique allows the lightweight carbon joiner box’s to slide off easily from the aluminium after its removed from bagging. The greaseproof paper simply twists out and away from the inner shell of the box’s. Voila, perfect lightweight wing joiner box’s. The same technique is used to produce the carbon tubes now used in the Fin/Rudder. (See pics). New lightweight wing joiners have been produced to keep the weight/inertia down towards the tips as low as possible. The original method of production resulted in each set of joiners weighing approx. 25g. A set of the new joiners weighs approx. 9.5g! At the moment we are carrying on using our original method of spar set-up for the wing tips. Needless to say there is a lot less stress on the wings at the tips compared to the centre section. If however it proves to be the case that the wing tips need or would benefit from the new spar construction method, albeit with a small increase in weight, we will do so. A simplified/lighter method of attaching the fin/rudder to the boom has now been designed. (see pics). One thing that really helped us with the continuing development of the PROGLIDE was the acquisition of a 3D printer. (Every modeller should have one!). We are using this to produce all sorts of PROGLIDE parts including, motor mounts, servo frames, tail pod twin servo carrier, wing end ribs, control horns, centre panel Mpx wing/fuselage plug/socket holders, small part moulds and so on. It’s probably the most useful thing I’ve ever bought for modelling. It took me a bit of time to get on top of it all but it was worth the effort for sure. Finally, this leads me on to our latest development, the PROGLIDE EXTREME. We are currently both building a reduced span (3.55m) version, which will still be light (1150-1250g AUW) but that can handle being ballasted with up to 700-800g of ballast for windy weather use without excessive wing flex. Well that’s the plan at least. The smaller span should also help the tight turning ability in small thermals. Kevin has already produced his EXTREME’S super stiff centre panel using the new centre panel spar lay-up and to quote his words ”I think it would take an F3J tow”. I find that observation reassuring! However, as always, only time and testing will confirm this. The pics attached to this update say a thousand words but if you have any questions please feel free to ask and we will do our best to answer them. Colin Paddon / Kevin Beale
    1 point

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