Stuart Eggerton Posted February 16, 2013 Share Posted February 16, 2013 Hi everyone, I saw the 'Gemima' vintage model in February's RCM&E magazine and something just captured my imagination. I have always liked vintage models and this one was just crying out to be built, it might as well have had a 'build me' sticker on it lol! I was particularly drawn to the fact that it's easy to build and also flies nice and slowly I have fond memories of a fellow RC pilot flying a Junior 60 in the late 80's, and I remember always wanting the Veron Deacon and staring at the box in the model shop, but never got into IC. However due to the advent of electrickery it has opened up a plethora of new opportunities for model subjects There are several people on this forum who are already building Jemima and the progress I have seen is great especially from people returning to the hobby, it's a good thing to see that. I do have model building experience, which helps and it will be refreshing to build something that is traditional. So here goes, this is my build log. Please feel free to ask ask questions of what I am doing and remember Jim Newberry (the model designer is there to help as well). I must try not to make 2 right hand wings! Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 16, 2013 Author Share Posted February 16, 2013 First step was to determine how much balsa to order etc, which was done and ordered from SLEC as well as wheels, wheel collets, piano wire for the undercarriage and also the elevator joiner. I was lucky to have quite a lot of 1/4 inch balsa sheet in stock so this comes in useful for things like the centre of the tailplane, fuselage sides at the rear and front, and the wing tips. I did not get a balsa stripper but did purchase some 1/4 x 1/4 balsa strips (now how lazy was that!, Sorry Jim!) The tailplane is only shown in one half and I found the easiest way for me to duplicate the other half was to photocopy it and then trace the lines through. If you do this please ensure your photocopier produces accurate copies! I then joined the photocopied tailplane half to the original plan using masking tape, it does peel off a bit of the ink from the plan when you decide to remove it but is satisfactory in keeping the plan in the correct position as you build. Below you can see the tailplane has been built up on the plan following the instructions in the RCM&E magazine. Please note that the spar in the middle of the tailplane runs full length. When you come to fit the fin, you must notch the bottom of the fin to allow the fin to slot into this spar. This photo does not show the ribs near the centre of the tailplane. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 16, 2013 Author Share Posted February 16, 2013 This picture shows the ribs in the centre of the tailplane after having been added. I have also made the elevators from 1/4 inch balsa sheet and added lightening holes to save weight having to be added to the nose! The spar ends need trimming and the ribs need shaping, the leading edge and tips as well. The elevators need shaping too. The tailplane tips also have lightening holes added. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 16, 2013 Author Share Posted February 16, 2013 Completing the tailplane Below is the completed tailplane and elevators. The leading edge of the tailplane has been rounded as well as the tailplane tips, the trailing edge of the elevator and the leading edges of the elevators. The top ribs have been sanded to profile and the elevator sanded to taper as shown on the plan. I left the elevator trailing edge about 2.3 - 3mm thickness so as not to make it too thin. Below is the completed tailplane assembly from a different angle to show rib profile better. Rudder and Fin The next stage is to make the rudder and fin. I made the fin first and then the rudder, building onto the plan, which I covered with clingfilm, which is good! After building the rudder I traced the correct rudder profile using tracing paper and a pencil, flipped the tracing paper over onto the wood, and with a pencil just rub the back of the paper (like coin rubbing), this transfers the pencil line drawn on the back of the paper onto the wood and allows a nice outline to be cut out. Below is the finished fin and rudder after shaping and sanding. Again the leading edge of the fin has been rounded as well as the rear of the fin and the leading edge of the rudder. The trailing edge of the rudder has been tapered. Please note the notch in the fin to receive the spar in the tailplane. The fin and rudder from a different angle Edited By Stuart Eggerton on 16/02/2013 21:22:02 Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 16, 2013 Share Posted February 16, 2013 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 16, 2013 Author Share Posted February 16, 2013 Hi Stewart, well I have made a few models and I suppose you get better with each one you make. For me it's using the correct tools have made things easier, I used to have very few!. Also practise helps and coming up against challenges that test you and you can solve are satisfying too. Well it looks like you are doing very well yourself Ok the lightening holes. First I determine the centre of each hole on the plan, transfer this info to the wood by measurement. Then use a compass and pencil and draw the circles with a compass on the wood. I then cut with a scalpel a good 2-3mm inside the circle (so I have 2-3mm excess wood left. Then simply go round with the scalpel and tease out the wood. I enjoy this sort of work. Finally when getting really close to the pencil line use some sand paper rounded through the hole to finish the holes. I am sure there are easier and better ways to make holes, but that's my way and it works for me! Edited By Stuart Eggerton on 16/02/2013 21:41:46 Edited By Stuart Eggerton on 16/02/2013 21:42:18 Quote Link to comment Share on other sites More sharing options...
Ruprect Spode Posted February 16, 2013 Share Posted February 16, 2013 The tailplane ribs suggest it is a 'lifting' tailplane. Is the angle of incidence of the main wing to be quite high? Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 17, 2013 Author Share Posted February 17, 2013 Hi Ruprect, yes the airfoil shape of tailplane will make it a lifting tailplane, used to have one of those on my Keil Kraft Caprice free flight glider. Not sure what the decalage is, will have to consult the plan. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 18, 2013 Author Share Posted February 18, 2013 The Fuselage, making the sides I started by photocopying the tail section of the fuselage from the plan, then attaching it to the plan in the correct position using masking tape. Then covering the plan with good old cling film, knew it was more versatile than just keeping my sarnies fresh Then make up the front fuselage part from 1/4 inch balsa sheet. I needed to laminate two pieces of balsa to get a big enough piece. Then cut two identical pieces using tracing paper and pencil as described above for the rudder part. Also made the triangular gussets and the rear fuselage panels from 1/4 inch balsa sheet. The next stage is to pin down / weight down the balsa sheet nose part and then one by one the 1/4 x 1/4 balsa strips which make up the fuselage frame. The results of this are below. I would suggest using pva wood glue or similar as cyano can leave the parts a bit brittle when it comes to having the bend the two parts to receive the formers. Remember to add the triangular balsa gussets and the rear balsa part which fills in the space below where the tailplane will sit. Then I covered the fuselage side I had just made with another sheet of the trusted cling film and made the second fuselage half directly over the first (thanks Jim Newberry for this tip Below are 2 completed identical fuselage sides. Edited By Stuart Eggerton on 18/02/2013 22:15:50 Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 18, 2013 Author Share Posted February 18, 2013 Making the fuselage formers The formers for the fuselage are made from 1/4 x 1/2 balsa and consist of two vertical and two horizontal members for each former, these when made should look like this. F2 - F7 Adding the formers to the fuselage Now with one of the fuselage sides placed and held flat on the building board, add each of the 4 main formers F2, F3, F4 and F5 Ensure they are square to the fuselage sides using an set square, don't rush this step!!!! take your time to get everything square and allow adequate time for the glue to cure. Then mark the middle / centre of the bottom of formers F2 - F5 and offer up the structure to the plan. Glue the other fuselage side to the formers ensuring the formers line up with the plan centre line and also with the fuselage side. Pic after the 2nd fuselage side has been added and glue dried (structure was then removed from plan for picture purposes) Edited By Stuart Eggerton on 18/02/2013 22:30:03 Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 18, 2013 Author Share Posted February 18, 2013 Rear Formers Tonight I have just added formers F6 and F7 to the tail section as shown in the pictures below. I had already pulled the tail together and glued it, ensuring that the 4 previously glued formers lined up with the centre line of the plan and extended the drawing by tracing the very rear part of the fuselage and adding to the plan. When bringing the very rear parts of the fuselage together make sure they are suspended a little above the plan to stop the tail 'sticking' in an incorrect position. I just chocked the fuselage up on 1/8 th balsa strips to do this. Then I could align the tail parts perfectly and then glue and allow to dry. I had a bit of trouble with a adding the formers F6 and F7 because I have used cyano glue to build my Jemima. This is strong but brittle, so any attempt to pull the fuselage sides together caused the joint just behind the TE of the wind to pop out/break. I went with it though as the bottom stringer is continuous and was in tact, so finally added the formers after sanding the sides for a slight taper/angle due to the fuselage sides coming together. Then held with clamps and pins after glueing with PVA. Cyano is very good but it does seem brittle in some circumstances. Finally where the joints had failed due to bending I worked lots of PVA into them and hopefully this will set OK. The joints that failed can be seen just in front of the metal dumbbell bar used to weight the model down. Another angle shwoing added formers, F8 to be added yet and front ply nose former F1 as well. Quote Link to comment Share on other sites More sharing options...
Jim Newberry - Nuviation Ltd. Posted February 18, 2013 Share Posted February 18, 2013 This looks great Stuart, glad it's coming together well! Jim. Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 19, 2013 Share Posted February 19, 2013 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 19, 2013 Author Share Posted February 19, 2013 Thanks chaps Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 22, 2013 Author Share Posted February 22, 2013 Formers F8 and F1 Glued former F8 in place towards the rear of the fuselage, as Jim says this is comprised of only two horizontal elements with no vertical elements. Next the front former F1 was added, this is the former the electric motor is attached to so needs the correct down thrust angle which is set by the front of the fuselage sides already. My first attempt at glueing F1 between the fuselage sides resulted in the centre line of the former being 2.5mm to the left of the fuselage centre line. After much head scratching I think that I have used too different grades of balsa in the fuselage sides near the nose, resulting in uneven bending. I placed the fuselage on the plan, lining up all the previous formers including the tail on the fuselage centre line and used weights to hold it down. (knew those dumbbells would come in handy one day!) then coated F1's sides with PVA to give me time to work and used a 'G' clamp to hold the fuselage sides tight up against F1. The fuselage nose still wanted to wander off centre, so I used more weights to nudge it back onto the centre line, and simultaneously added triangular gussets between the fuselage sides and F1 Once dry the fuselage had remained lined up with the fuselage centre line! yay! Below is a picture of F1 curing on the workbench. Edited By Stuart Eggerton on 22/02/2013 18:58:43 Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 22, 2013 Author Share Posted February 22, 2013 Photo showing inside fuselage with the triangular balsa fillets glued to F1. The ply doublers were added at the wing dowel stations, made from 1/16th plywood. Diagonal fuselage bracing parts I started from the bottom of the fuselage, adding the diagonal 1/4 x 1/4 balsa strips running from F3 backwards to the tail. I also added the diagonal bracing between the formers on the top of the fuselage (also 1/4 x 1/4) from F5 backwards. You can see the results of this in the picture below. When viewed from above it looks as if the two sets of bracing are crossing each other (which they are actually, but at different heights!) Rear fuselage spine and roof I added the 1/4 x 1/4 inch balsa spine along the top rear fuselage on top of the newly fitted diagonal bracing pieces and existing fuselage formers. I then added the transverse members which make up the roof part (also 1/4 x 14 balsa). You can see this work in the picture below. The transverse members were then shaped to a 'roof pitch' Shape as shown below using a scalpel and a sanding block. I am pleased with how the model is progressing Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 22, 2013 Share Posted February 22, 2013 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 22, 2013 Author Share Posted February 22, 2013 Hi Stewart, yes a super bit of design by Jim indeed. I once tried to design a 3.5m span glider, but it never flew correctly . I was only 16 at the time and used full 1/16th sheeting top and bottom of the wings, so maybe it was a bit on the heavy side. Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 23, 2013 Author Share Posted February 23, 2013 Ruprect, in reply to your previous quesion about wing / tailplane incidence, I have just measured from the plan and the tailplane and the wing are set to the same angle of incidence, so there is no decalage. Quote Link to comment Share on other sites More sharing options...
Jim Newberry - Nuviation Ltd. Posted February 23, 2013 Share Posted February 23, 2013 Hi Stuart and Ruprect, The decalage is about 2.5 degrees. Remember, Stuart, the incidence of the wing is measured from the centre of the leading edge radius to the apex of the trailing edge, not from the flat bottom of the section. As for the lifting section tailplane, the model would no doubt fly fine with a flat plate tail - I only used the lifting section because I like the look of it and it adds a lot of strength for very little weight. I actually considered giving the same treatment to the underside as well to create a chunky symmetrical section but decided against it on grounds of complexity. Jim Quote Link to comment Share on other sites More sharing options...
Ruprect Spode Posted February 23, 2013 Share Posted February 23, 2013 As I presumed, thank you Jim. Quote Link to comment Share on other sites More sharing options...
Adrian Day Posted February 23, 2013 Share Posted February 23, 2013 hi sorry to post this on here been following your posts n build, been told this was a free plan than was in rcme ... but was just trying to find the addition with the plan in, would anyone know what the months / year it was please Regards Adrian Quote Link to comment Share on other sites More sharing options...
Dale Gibson Posted February 23, 2013 Share Posted February 23, 2013 Hi Adrian, It was the free plan in Feb mag this year. Dale. Quote Link to comment Share on other sites More sharing options...
Adrian Day Posted February 23, 2013 Share Posted February 23, 2013 thank you Dale ... havin a thick moment ... when i get the issues i take out the planes and the pages an put them in a folder ... thats why i didnt see it in reading the mag ... thankyou for letting me know .. now i know what i will be getting up to next .. Regards Adrian Quote Link to comment Share on other sites More sharing options...
Stuart Eggerton Posted February 23, 2013 Author Share Posted February 23, 2013 Hi Jim / Ruprect, sorry I did just measure the decalage from the bottom of the flat wing (oops) well you learn something new every day. I am starting on the wing already, almost glued all the ribs into flat centre section. Have come to a standstill at the moment with the fuselage as need to get an electric motor. Jim would 250 watts or 300 watts be better to fly with, what has your experience been.? I do like to do aerial photography and may need to carry and 8 oz or so digital camera onboard the model, would I need 300 watts in this case? Edited By Stuart Eggerton on 23/02/2013 20:42:34 Quote Link to comment Share on other sites More sharing options...
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