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