Alec Turnbull Posted March 25 Share Posted March 25 I have, for a while, been looking out for a glider for those lovely summer days that will be coming along soon.......maybe. Nothing I fancied has come along, then I remembered, the first model I built from a plan was a glider, Rex 1a. I had literally hundreds of flights with it. The club I belonged to then in the mid 1970's was the Thanet Model Flying Club in Kent where thermal soaring was quite a big thing, after the Rex I went to a Radiosailplanes Wildfleken, I had two of those, then for the 100s comps a Scirroco all good flyers and lots of fun. All these were hand launched with a tow line, but at age 72 I am not going to do that any more or ask my fellow club mates who in many cases are older than me! So I wondered how hard it would be to fit a motor and lipo into the Rex, I think I have all the right bits in stock so lets get on with it. I no longer have the original plan but handily it is to be found on Outerzone along with original article from Radio Modeller, copy of which is just below This was fifty years ago so I really do not remember much of the build, but it must have been simple as it was my first fully completed plan build after a false start with a Big Wig, so this should be a quick build provided I can squeeze in the motor and battery, so I will start with the fuselage as that is where all the main changes will be. Overlaying the motor that I intend to use an Overlander T3548/05 ( purely because it is in stock) and a folding prop a Graupner 13/7 (ditto) I can see that I can keep the side elevation almost as per the plan by moving the front bulkhead forward a little and at the same time arranging a little down thrust ( as I have seen that in other plans that I have looked at. I have increase the width of the bulkhead just a tad to give me a bit more room. This is the original unaltered drawing, the download from outerzone is not that good but will suffice, I will do away with the wirework for the tow hook, and face the underside of the fuselage with 1/16th ply. Motor and prop will fit about here Plan amended to suit Front bulkhead enlarged just a little for a bit more working room, the plan says balsa but for obvious reasons I have substituted 1/4 ply for this one to mount the motor on The rest of the fuselage is per the plan and a very simple box so quickly knocked up. Here is the fuselage more or less complete, with a canopy made of some scrap balsa, which is shown here with some stopper and primer on as I could not get a good finish on the bare wood with just sandpaper so filled the sanding grooves with stopper and high build primer and then sanded down with wet and dry, it will be covered with some black film So now I know the electric conversion is going to work and not look too bad I will get on with tha tail and wings. 4 Quote Link to comment Share on other sites More sharing options...
Andy Gates Posted March 25 Share Posted March 25 I was going to suggest working out where the battery pack will need to be so the formers can be adjusted - a little late I think! I have done much the same with the Graupner Amigo II and the Galaxy Models Condor, both flew great until wind shear tore the wings off the Condor at 1800ft from memory. Took ages for the wing panels to come down. Good luck with your modifications. Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted March 26 Author Share Posted March 26 8 hours ago, Andy Gates said: I was going to suggest working out where the battery pack will need to be so the formers can be adjusted - a little late I think! To get battery in I did change a few things, I am using a 3s 3500mah lipo. so I used ply instead of balsa for the relevant formers to support the weight and the underside sheeting is1/6th ply, the holes in the formers shown on the plan were just to allow for the wiring so I enlarged those to suit the lipo which slips in nicely around the c of g position, the servos I have moved back behind the lipo for ease of access which will also allow me to slide the lipo back and forth to adjust the c of g position if required, I did intend to mention all this before but got carried away and pressed the send button! I had to make a few small 'adjustments' to ease it in, plenty of room to move it forward if I have to as the next bay will be empty apart from the esc. 1 Quote Link to comment Share on other sites More sharing options...
John T Posted March 26 Share Posted March 26 Like many other gliders of this era, I think this is a perfect model for converting to electric. I wouldn't be surprised if you find it still needs a touch of down elevator while under power though, even with 3 degrees of down thrust. I think I've got the plan for this somewhere, but it's one of those models that I never quite got round to building. I was never totally convinced with the wooden dowel wing joiners though, although they obviously did the job OK. I'll be watching this build with interest. Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted March 26 Author Share Posted March 26 1 hour ago, John T said: Like many other gliders of this era, I think this is a perfect model for converting to electric. I wouldn't be surprised if you find it still needs a touch of down elevator while under power though, even with 3 degrees of down thrust. I think I've got the plan for this somewhere, but it's one of those models that I never quite got round to building. I was never totally convinced with the wooden dowel wing joiners though, although they obviously did the job OK. I'll be watching this build with interest. On my first Rex, for some reason that I have forgotten, I used some thick wall aluminium tubing and piano wire inserts instead of the wooden dowel, they rattled and I was not happy with that, plus a bit heavier than the wood, this time, as we will see soon, I have opted to stick with the plan, which says 7/16 beech I couldn't find any of that so I have some 1/2 inch or 12.5mm a wee bit thicker. I am sure this will be Ok as the loading in the wings will not be anything like the stresses imposed by a winch or bungee. I did consider cardboard tub and carbon rod, but in the end went the cheap route! Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted March 26 Author Share Posted March 26 Cracking on with this build now! Whilst building the fuselage i made a start on the tail end, all very simple and lightweight, Here is the horizontal stab, dry fitted and waiting for glue And now all finished wit,h the vertical stab, found all the wood I needed in the scrap pile so a good use for all that balsa saved from other projects The only changes to suit my preferences were to alter the way that the tail is mounted on to the rear of the fuselage, the plan calls for piano wire hooks and rubber bands, that sound too fiddly for me so I have substited some ply infills with some captive nuts epoxied in, I can then insert some small button head screws underneath through the ply mounting plates. Close up of my new tail mounting arragement, the eagle eyed of you will probably notice that the two centre panels are of different widths, this is exactly as the plan is drawn but I did not notice until it had all come together, not sure if that is a fault in the original drawing or a distortion in the Outerzone download, any it does not make a difference I will carefully measure everything before drilling any holes in the mounting plates Here are the mounting plates, looseley placed, I will mount with glue and drill to suit once the fuselage in covered in the next day or two, it will be in white film. 1 Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted March 27 Author Share Posted March 27 Here is a mock up of where we are so far, control runs in, fuselage and tail ready for covering probably tomorrow. I want to get on with the wing construction as much as possible before the Easter weekend as the family will be home, guests arriving, which means that I will not be allowed in the garage for the duration! So, the centre section is built first, in one piece then cut in half once skinned. in the article Roy Salter mentions that the wooden dowels inserted as a sort of jig to keep it all lined up are sacrificial and cut in half then disposed of, I dont think that is nessessary so I will save them. First of course I have drawn some templates on some thin ply, the centre section is a constant chord, the smaller rib is the outer one on the wing tips, the intermediate ribs are not shown on the drawing so I will use the sandwich method to produce two (handed) sets. The centre ribs which take the wooden dowels are 1/8th ply, easy to do on the band saw, but I don't know how I managed that on my original model I must have used a fret saw, I really cannot remember! I managed to find enough scrap balsa to make all the balsa ribs, these are the centre section, the rest are 1/8th ply 8off The ply ribs are done, drilling the 12.5mm hole for the beech dowel was a bit tricky and even then the dowel was a very tight fit, so I wrapped some sandaper around the base of a drill and relieved the holes until it was a nice slip fit, I also sanded the dowel with very fine sandaper and then gave it a couple of coats of furniture wax as a form of lubrication, seems to have done the trick. The rest was easy, first laid down the bottom sheeting and cap strips The all the ribs using the dowels as suggested in the Roy Salter article to jig it all together, and also I have fitted the dihedral braces that will slip into the outer panels I have left a small gap between the centre ribs, enough to get a razor saw between them to cut the wing skins once the glue has dried and I have lifted it off the bench. Top skins and cap strips on, I have marked to centre line to guide the razor saw, hold my breath and cut it in half once all the glue has dried overnight 4 Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted March 28 Author Share Posted March 28 Much to my amazement my plan to cut the wing centre section in half worked out well, I did cut the main spar before I fixed the top skin in place, as it was very close to the big dowel, I thought it may present a hurdle. Success! Managed to save the dowels, and they slide in and out well, no slop so I am quite happy with the way it has turned out. Made a start on the outer panels That is about as far as I can get now until after the Easter weekend 2 Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted April 2 Author Share Posted April 2 Both main wing panels finished now and ready for covering Not shown on the drawing but I thought I would cut a few lightening holes in the wing tips, whats not there can't weigh anything is what I thought! What is shown on the drawing is a small fairing that will help to blend in the fuselage to the wing centre section, I think it could possibly be left off, and I think I probably did on my original model, this time I have had a crack at it. Quite a small piece and a bit fiddly to make, but I have stuck it on the wing now, may need a slight adjustment to fill in the space Once the glue is properly dry in the morning I will tidy it up before starting the covering 1 Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted April 3 Author Share Posted April 3 I have been doing a bit of covering today, we are nearly there but only so much covering in one day so finish tomorrow, maybe..... A mock up to see how its coming along With a bit of luck may be finished by the weekend Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted April 8 Author Share Posted April 8 On 03/04/2024 at 13:29, Alec Turnbull said: I have been doing a bit of covering today, we are nearly there but only so much covering in one day so finish tomorrow, maybe..... A mock up to see how its coming along With a bit of luck may be finished by the weekend Well....finished target missed as I underestimated the amount of covering film required and had to order some more, any how all done now, one final mock up before I finish all the little bits and pieces. plus I need to obtain some 6'' wing bands, the only ones I have in stock are far too big, but... nearly there now. Looking forward to some nice weather, whenever that might be......! 5 Quote Link to comment Share on other sites More sharing options...
John T Posted April 10 Share Posted April 10 Looks good Alec, and you've inspired me to get on and finish my latest model. Let us know how you get on flying it when the weather finally relents. Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted April 11 Author Share Posted April 11 Finished all the little tyding up jobs, wing bands arrived so I put it on my Multiplex c of g balancer thingy. With the lipo pushed forward as far as it can go it balances right on the money, so its good to go, roll on a bit of sunshine...... Total weight 3lbs 10ozs, not sure whether that is good or not, no recommendation in the build article,but it is what it is. 1 Quote Link to comment Share on other sites More sharing options...
Shaun Walsh Posted April 11 Share Posted April 11 2 hours ago, Alec Turnbull said: Finished all the little tyding up jobs, wing bands arrived so I put it on my Multiplex c of g balancer thingy. With the lipo pushed forward as far as it can go it balances right on the money, so its good to go, roll on a bit of sunshine...... Total weight 3lbs 10ozs, not sure whether that is good or not, no recommendation in the build article,but it is what it is. Surely there must be a market for square spinners?😉 1 Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted April 12 Author Share Posted April 12 22 hours ago, Shaun Walsh said: Surely there must be a market for square spinners?😉 Very funny!....... I am surprised one of you wags had not come up with this earlier ! I would have loved to have arranged a more streamlined nose section, the motor I have used is quite fat, there is no meat at all in fuselage sides to carve away, I did consider getting a thinner inrunner which would have allowed to redesign the nose section, but that would have changed my original concept of a quick build, I did knock this off in a few days after all. No one will notice the blunt front at a few hundred feet up there (on the assumption it does get up there of course). What I was really after was a replacement for my old Radio Sailplanes Wildflecken and I have found actually something similar now, (coming here soon)so this Rex will be a practice model, blunt nose nor withstanding I am quite pleased with it! Quote Link to comment Share on other sites More sharing options...
GrumpyGnome Posted April 12 Share Posted April 12 On a practical note, if you open the throttle slowly (maybe even if you do it quickly), the prop blades may catch the corners of the fuselage...... maybe check now rather than when it's 200 feet up? Quote Link to comment Share on other sites More sharing options...
Shaun Walsh Posted April 12 Share Posted April 12 1 hour ago, GrumpyGnome said: On a practical note, if you open the throttle slowly (maybe even if you do it quickly), the prop blades may catch the corners of the fuselage...... maybe check now rather than when it's 200 feet up? My comment was a lighthearted one. But the prop blades will also not fold properly unless the prop is vertical or horizontal. Maybe fit a spinner that's the same dimension as the fuselage diagonal measurement. Quote Link to comment Share on other sites More sharing options...
Alec Turnbull Posted April 12 Author Share Posted April 12 3 minutes ago, Shaun Walsh said: My comment was a lighthearted one. I knew that Shaun....The prop seems to fold back Ok, not as much as if the nose as round but near enough no matter what position they stop. 1 hour ago, GrumpyGnome said: On a practical note, if you open the throttle slowly (maybe even if you do it quickly), the prop blades may catch the corners of the fuselage...... maybe check now rather than when it's 200 feet up? Have checked now Grumpy, had not thought about that, but as soon as the blades move they are clear of the corners, close tho! Quote Link to comment Share on other sites More sharing options...
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