Harry Twist Posted October 29, 2019 Share Posted October 29, 2019 Hi All, Firstly - thankyou to Martin Gay and Gordon Studley for the planning, design, production and general "effort" that has led to us obtaining our F-86 PSS kits. Also many thanks to Phil Cooke for his detailed work in supporting and promoting this mass build 2020 project. I've decided to attempt the scheme shown below for my F-86. Its a USAF F-86A of the Montana ANG, target tug, circa 1955 at Nellis AFB. Profile view: Model kit (not by me!) Edited By Harry Twist on 29/10/2019 22:25:31 Quote Link to comment Share on other sites More sharing options...
Phil Cooke Posted October 29, 2019 Share Posted October 29, 2019 very nice scheme that Harry! The silver and yellow and blue do go well! I look forward to seeing your Sabre develop - Nearly time to get going! Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted October 30, 2019 Share Posted October 30, 2019 Yellow and silver, looks familiar Phil Nice variant Harry, not long before you start now! Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 2, 2019 Author Share Posted November 2, 2019 Off we go! Its Nov 1st, so, being a miser I've turned over my piece of plasterboard building board and rescrewed it down on the other (clean!) side. I've then spent a little time making a start on the F-86. I started by fettling the wing jig sub pieces, just minor trimming needed. Then I cut up the wing plan sheet and then added extended lines for the ribs and wing spars. Once done I assembled the wing jig sub pieces and then finally assembled the wing jig, on the covered plan, carefully ensuring it all sat square and flat on the bench. I did add some triangular support as suggested by Martin in his gamma build. Couple of shots... Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 3, 2019 Author Share Posted November 3, 2019 Hi All, got a little more done over the weekend. Once dried, the wing jig was carefully removed from the plan and stored. Right and left lower wing sheets were then made up. Careful cutting gets one wing panel from 2 x 3"x 36" lengths. These were joined by the "tape on the back, fold along the tape line, glue in the fold, then unfold, wiping any excess away and adding weights to the new panel whilst drying" method. Once the panel was dry the rib and spar locations were added and the lower spruce spar cut and glued in location. Finally, I looked at a method for adjusting the spar slots in the ribs to get the correct spar/rib angle at the base. A simple jig to hold the rib made from scrap balsa and two clothes pegs helped! Photos below... Edited By Harry Twist on 03/11/2019 23:57:11 Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted November 4, 2019 Share Posted November 4, 2019 Lots of good tips Harry cheers. Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted November 4, 2019 Share Posted November 4, 2019 Nice little jig Harry, good work Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 5, 2019 Author Share Posted November 5, 2019 Hi All, Over the last couple of nights I have pushed the wings on a little more. Both lower skins now made, with centre spars and false TE's added - and whilst drying I sat them, with weights on, in the wing jig to "train" the balsa to the anticipated curve. Each rib was them trimmed to the correct angle for the top and bottom spars and the false TE, simple angle jigs helped this. The wing jig was then relocacted into position over the plan on the building board and although square, it was lifting a little in places - so the solution involved a few moulding pins and a small hammer and then gently nailing it to the building board! With the wing skin sat in the jig I did notice that there was a gap between the underside of the wing skin and R1 - whereas all the other ribs sat neatly. To force the skin down onto R1 would have created a largish step form R1 to R2. So to remove this step/gap I glued a piece of scrap wing sheet balsa over the top of the twin R1 centre braces in the jig - this took up the gap and the wing sits much better now at the root. Next stage was to locate the ribs in their final position and glue them. (the false TE was located prior to any ribs going in). To keep the skin "in the seat" I sat weights between each rib as I glued, and finally placed a piece of waste spruce in the slot on the top of the ribs and weighted down on this. So as of tonight - I have located all the ribs on the right wing apart from R1. As an additional aid to keeping the rib leading edges located on the sheet I wedged a piece of 1" triangle below the front of the sheet. Photos....offer better explanations than my words! Additional strip over R1 area- indicated by blue pen Weighted between ribs Right wing ribs glued in situ Rib leading edge trimming jig Edited By Harry Twist on 05/11/2019 22:17:00 Quote Link to comment Share on other sites More sharing options...
Steve McLaren Posted November 9, 2019 Share Posted November 9, 2019 Nicely done Harry. I'm hoping to catch up to this stage today. I made the wing skins last weekend, but no progress during the week. I can see that they're useful, but why do you have so many lead/acid batteries?? Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 10, 2019 Author Share Posted November 10, 2019 Hi Phil, I think the lead acids came to one of our model club meets, they were tired out but I saw them as weights! Just a bit of "repurposing" really! I've got 4, they're approx 2lbs each in weight so are quite useful. Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 10, 2019 Author Share Posted November 10, 2019 Really enjoying reading all the F-86 blogs, it's great that some people have started wing first and others fus first. Bit more progress on wings, false leading edges and hinge blocks added. Main work this weekend however has involved cutting, sizing and fitting the shear webs. Enjoying the build, thanks again Martin and Gordon Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted November 11, 2019 Share Posted November 11, 2019 Good progress there Harry. There's a lot of shear webs! Cyano or aliphatic? Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 11, 2019 Author Share Posted November 11, 2019 Hi Chris, 48 shear webs, each lovingly cut and trimmed, done over 3 sessions. Aliphatic all the way. Nice progress on your fuselage and thanks for sharing the 10 planking tips! Quote Link to comment Share on other sites More sharing options...
Steve Houghton Posted November 11, 2019 Share Posted November 11, 2019 Harry, another meticulous build on its way, I see. Thanks for the R1 tip, to be noted when I start my wings. Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 18, 2019 Author Share Posted November 18, 2019 Hi All, I have been slowly inching the Sabre along a bit more. After a bit of thinking and head scratching I've decided that the drop tanks are so much a feature of the Sabre that I wanted to try to incorporate them into the build. Since they would be damaged easily on landing I'm planning for them to be jettisonable. So using a 1:72 Airfix model I have tried to scale up the location on the wing and the size of the tank and pylon to suit a 1:10 model. Disclaimer(!) - these are my kitchen table/ pen and pencil numbers and may not be 100% scale accurate! I reckon the tank pylon sits midway between R8 and R9, or 30cm from the centreline. The tank itself is approx 34.5cm long and 6.5cm in diameter at its widest. (its basically a torpedo shape with fins and a flattened top, although there is more than one tank type!). So leaving the tank detail and construction until later, I have added the first part of a delivery system to the wings (basically I have copied John Heys proven method from the PSSA A4 mass build - thanks John!). Its a central servo driving a piano wire pushrod to the chosen location, the end of the rod push/ pulls through a hole in the pylon/keel of the tank. It did take some time to set it up - and you need to put holes through all those lovely ribs, it has also meant chopping away a portion of the front of the two R1 ribs to accomodate a servo location. The wings were then planed and sanded to approaching a near finish state, although the top skins have not yet been added. I have now set them aside temporarily and moved onto the fuselage. Drop tank location and size - ( ignore right hand location/ image of tank- I had a plan and elevation view on the same piece of paper and simply laid it below the wing, left hand tank drawing is "in location" between R8 and R9). Tank delivery system- straw for support, plastic tubing either end, slightly larger internal diameter than piano wire diameter- sliding fit. Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted November 18, 2019 Share Posted November 18, 2019 Excellent Harry! Watching with interest. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 18, 2019 Share Posted November 18, 2019 This is indeed excellent engineering, Harry. Watching with interest. Cheers Chris Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 18, 2019 Author Share Posted November 18, 2019 So, taking a breather from the wings, it was time to make a start on the fuselage. First job was to tickle all the surfaces with fine sandpaper removing any loose particles and hopefully create a slight key for surface jointing. I then laid out each piece with its partner and checked for symmetry ( I also went a little over the top and labelled, in pen, all the left pieces with a discrete little "x" and all the right with a little "y". In addition I measured the longitudinal parts for equal length for left and right sides (F14 and f15). All was good here. I then dry fitted all the parts I could, a little work was needed here and there to ensure a good fit on some slots but no great issues were found. Subsequently I have started to assemble of some of the "sub structures" ( the central overwing block of three formers and F14, plus the tail block of F9, F15, and F10, they're all basically 90 degree joints. Once all the sub assemblies are complete, I'll locate all on the plan, add the keels and do a full fit before gluing. Some progress shots below. Parts laid out - I subsequently turned the upper fuselage plan around 180 degrees to be the right way up, so now building both halves the right way up ( I could'nt cope with upside down and reversed, I was bound to make a mistake!). Sub assembly 90 deg jointing, left side shows central crutch, F7 previously jointed at top, F4 under weights, F6 not yet glued in position. Right side shows rear sub assemblies F9 previously jointed, F15, F10 under weights. Clearly they're not sat in situ on the plan (!) since they're 90 degree joints I chose to sit the former flat on the build board and build upwards ensuring 90 degree joint with the longitudinal formers F14 and F15) and adding weights to the laid flat former. Then once dry turn the whole thing over ( like an egg timer) to glue the opposite former. They will be located on the plan later. Nose area - a sub assembly in itself Edited By Harry Twist on 18/11/2019 21:22:58 Quote Link to comment Share on other sites More sharing options...
Steve McLaren Posted November 19, 2019 Share Posted November 19, 2019 Nice work Harry. I'm interested in the tank drop mechanism. What size servo do you plan to use? and does 1 servo do both tanks? I'm trying to visualise the geometry of pushrods meeting the servo. Quote Link to comment Share on other sites More sharing options...
Martin Gay Posted November 19, 2019 Share Posted November 19, 2019 Steve, here is the original blog by John H: **LINK** Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 19, 2019 Author Share Posted November 19, 2019 Hi Steve, one servo - sat at the centre, it will only make one movement per flight, pulling two lightweight piano wires around 5mm (one wire per wing). Not decided on the servo yet, but it will be a light one! Pushrod geometry, nothing complex hopefully, 90 degree bends taking the pushrod up to the servo. Each pushrod end then located into opposite ends of a servo arm. There's more detail in the John H A4 build - thanks Martin for the link. Edited By Harry Twist on 19/11/2019 23:34:24 Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 23, 2019 Author Share Posted November 23, 2019 Hi All, I've moved the fuselage on a little, well one half of it anyway! I cut the spines from sheet and decided to cut them slightly oversize at 8mm x 3mm. This was to ensure that the very top of the formers sat on the spine and not slightly below it. I used the straight top spine as the starting point, pinning it to the plan and ensuring all the touching formers sat in location and square. I then pinned, clamped, glued and weighted the combined nose unit / central crutch / top spine and the tail unit. Once dry I added the curving bottom keel as one piece, curved and pinned. Again, once all dry I added the F3 F5 formers and the longitudinal stringers. So for me, the fuselage framework ended up as a three stage assembly process. I did have an issue with the lower stringer, which at full length along the curve just about sat on F1 and F10, but not enough for me to be happy that it was secure front and back, so I scarf jointed a piece in, with the joint sat on the double former F4/F4a. The other two stringers were fine. Now onto the planking, prior to planking I sanded gently to ensure all the stringers sat flush with the formers. I've cut my planks 7mm wide, parallel full length and have so far added 4 planks. I'm taking my time over this - trying to align the planks carefully and trying to visualise how it will look. It's great to see and read all the ideas, guidance and sharing of information that's going on in the Sabre build blogs. Happy building! Bare framework completed - one half only Short scarf joint at F4/F4A- the dark lines at the former /keel joints are not gaps they're blue pen ink lines delineating the locating/gluing boundary! Long view - curving keel, one piece of 8mm x 3mm. First planks - plank width here is 7mm, planks parallel nose to tail. Edited By Harry Twist on 23/11/2019 23:43:32 Quote Link to comment Share on other sites More sharing options...
John A H Posted November 24, 2019 Share Posted November 24, 2019 Posted by Steve McLaren on 19/11/2019 21:11:53: What size servo do you plan to use? and does 1 servo do both tanks? I'm trying to visualise the geometry of pushrods meeting the servo. I used a Hitech HS65mg servo for the drop tanks on the A4 Skyhawk. I located the servo in one wing (so you don't have to cut into R1). Bend the pushrod (or pullrod !) diagonally up to exit the wing skin with one side going to the "front" and other side going to the "back" of the servo horn. I initially fit the wire before putting in ribs R1 and the ones outboard of the mounting - means you can slide it in and out of position while messing about trying to get the "line" and bend. Hopefully the pictures make sense of above comments - holes in ribs reinforced with 1/32 ply. Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted November 24, 2019 Share Posted November 24, 2019 Great progress already, Harry. Thank goodness, I don't have any external fuel tanks installed to my 'Dog' version, but then I do have enough pondering with the fuselage mods... Looking at the background of one of your pics, I noticed that you have been 'lightening' your battery box as well, héhé... Cheers Chris Quote Link to comment Share on other sites More sharing options...
Harry Twist Posted November 29, 2019 Author Share Posted November 29, 2019 Hi All, I've moved the fuselage on a little more. I have been worried about the major "glue up" required to join two part planked fuselage halves in one go. This involves, applying glue along all the major joint lines of the top and bottom spines, and along all the former joint lines, gluing and fitting the wing bolt plate, then aligning and clamping, all in one gluing "event". I did'nt trust myself to get this all square and had visions of glue everywhere and an out of line fuselage! So I tried an alternative. I part finished one fuselage half to the point of adding 10 planks (7mm wide). I then built the second half, section by section, onto the part planked first half. I starting by adding the straight top keel, then worked front to back, adding each sub structure in turn and allowing drying between each stage. At the end I added the stringers and the small part bulkheads of F3 and F5. Photos hopefully show all! Nose and battery box added, after top keel Central crutch and wing bolt plate, I adjusted the plate to move it back approx 5mm to sit against F7 Tail unit, clamps and more clamps Last addition- lower curved spine End product Edited By Harry Twist on 29/11/2019 23:23:23 Quote Link to comment Share on other sites More sharing options...
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