GrahamC Posted January 22, 2014 Share Posted January 22, 2014 At the end of last year, I saw a PB Models Calibre kit on ebay, and the price was right and so I bid on it and won it. I'd been thinking about buying one of these kits and prevaricated, so I was chuffed to get it for about half the going price! In a subsequent conversation with Paul Bardoe, I found out that the kit was probably one of the first made. For those who don't know, a Calibre is an enlarged PB models Bullet, and the plan and instruction CD are actually for the Bullet. The first job was to draw templates of all the pieces! The grease-proof-paper will be stored away enabling me to build a replacement fuselage if its ever necessary. The first bit of actual building was to complete the jigsaw puzzle that produces the two fuselage sides! Because of the size increase, there are more bits than in a Bullet! So far, I've glued in the doublers using Contact adhesive, and fitted the triangle stock to the fuselage sides with aliphatic resin. More soon! Edited By GrahamC on 22/01/2014 17:26:53 Quote Link to comment Share on other sites More sharing options...
Jim Purcha Posted January 30, 2014 Share Posted January 30, 2014 Looks like a very interesting build thread. To expensive to ship any UK kit across to Canada, but I'll follow along. Jim Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 8, 2014 Author Share Posted February 8, 2014 Hi Jim. Welcome! Time for an update I think.... My alternative fuselage jig in use. I use an old piece of kitchen work top. It has a straight line drawn along it and a number of lines at right angles. I simply use steel angle brackets screwed to the work top to hold things square. The jigsaw puzzle stage! With the Calibre you get a plan and instructions for a Bullet, and of course being larger, some parts are pieced together differently with the Calibre. Does this look right? Paul Bardoe was very helpful and said yes when I emailed him! A bit more jigsaw puzzle! I think the triangular piece was added to make it more interesting to work out what went where! Now the top deck is on and I've attacked it with the razor plane. A bit more to come off I think. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 8, 2014 Author Share Posted February 8, 2014 I've also made a start on the wings. I had a pair of these servo holders which I acquired when a club member retired from modelling. I thought that this would be an ideal use for them I made up some boxes from 3mm ply, and spruce blocks. These are to drop into the wings so that the servo holders can be fixed in space. Here they are drying. The top needs to be flat, the bottom doesn't matter, so they were left to dry on sticky tape... to which the epoxy won't adhere. I've let the boxes into the wing, and epoxied them in place. I've added balsa caps to the box and sanded it all flush. The calibre wing has an undercarriage plate on the bottom [shown] and a plate and balsa cap on the top of the wing. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 8, 2014 Author Share Posted February 8, 2014 A few questions for anyone who knows..... 1] This is my first balsa cowled model. So... how do you get the engine in and out? Can you get to the bolts on the underneath of the engine mount... or should I use screws to hold the engine in place? I'm using a ASP 90 two stroke. 2] This is my first large foam wing build. My 'feel' for design tells me that the epoxy bandage is not enough to hold these wings together, and that I should drop a 6 inch long ply spar into the wing at the thickest point to reinforce the join before applying the bandage. Am I worrying unnecessarily? The Calibre is 65 inch wing span. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted February 8, 2014 Share Posted February 8, 2014 1) you have to make the opening big enough to wriggle the engine in. I tap the mount and use allen screws. It might be an idea to solder nuts to brass strips that can be screwed to the back of the mount from the start as it's a real pain when a tapped mount strips it's thread! 2) My view of veneered foam wings is that 90% of the strength is in the stressed skin formed by the veneer, so the glass is there to couple the veneer across the join in the panels. I like to use two or three layers of thinner glass varying in width to form a feathered thickness - first layer maybe 6" (12" total width) each side, then 4" a side and the top layer a little wider than the fuselage. Saying that, I've never had a single 3" bandage as supplied in joiner kits that has failed, I just think the layered approach gives a less obtrusive result. Quote Link to comment Share on other sites More sharing options...
roger graves Posted February 8, 2014 Share Posted February 8, 2014 In days of yore ......long ago we used cotton surgical bandage with balsa cement rubbed through never failed, I would echo the above advice except I have only ever used a max of 2 strips with the thin one going on first which leaves less edges to sand away. Never have used spars and bandage and have never seen one fail at the joint. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 8, 2014 Author Share Posted February 8, 2014 Thank you both for the reassurance in terms of joining the wing. Bob... In terms of tapping the mount. [sorry if I am being dim!] Is that only with a metal mount or can you tap a glass reinforced nylon mount? I got a little more done this afternoon. I decided that adding a spar to the horizontal stabiliser might not be a bad thing. Hunting around in my wood box, I came up with a piece of 6x6 pine wood left from another build. [Stiff and strong and dirt cheap from B&Q] Cut a slot and dropped it in. Its about .5mm thinner than the balsa, so the piece cut out, went back in the hole, and the whole thing sanded flat. I find that the neatest way to butt join balsa is by joining the pieces together with masking tape before adding any glue. It means that you tend to end up with a very neat face on the taped side. Quote Link to comment Share on other sites More sharing options...
Jim Purcha Posted February 8, 2014 Share Posted February 8, 2014 Yes, you can drill and tap a fibreglass mount. Just have the proper drill size for the tap. I prefer to purchase these in sets. I have a Bridi 4 Seasons 40 high wing with a built up wing (wing joiners), epoxied together and than fibreglass cloth and epoxy finishing resin. It's holding up. Jim Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 17, 2014 Author Share Posted February 17, 2014 The wings have been glued together. I used the method recommended by Andy Green in his Curare Build. With a centreline marked on the end of each wing, and a piece of scrap wood tack glued on each end, the roots are brought together on a flat surface. The idea being that the incidence of the wing tips is the same, and any errors occur in the centre join where they will have less effect on flying characteristics. Assuming that the Dining room table is flat! [Checking it with the tilt meeter on an iPhone would suggest that it is!] There was a very slight discrepancy of about 2.5 mm at the worst point, at the front of the join. Once the epoxy between the wing panels had set, I applied a 4 inch epoxy bandage. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted February 17, 2014 Author Share Posted February 17, 2014 I've decided to go with self tapping screws for the engine. I noticed that the SLEC mounts actually come with screws for this purpose. Hopefully if the engine needs to come out, it should be possible. I do have another question! The nose leg i clamped in place by the engine mount. I'm not planning to have a steering system... but... Will that be OK? I can [just] twist the leg when the mount is done up. Will that be a problem? Is there anything I can do to improve matters? Some lock tight on the leg where it passes into the mount? Heres a little more progress.... The wing is now bandaged, and I spent a while fiddling around with the connection to the fuselage. A piece of string attached to the tail helps to get things square [ish!] This plate fits to the leading edge of the wing With the wing seated, and the holes lined up, I tacked the plate to the leading edge of the wing with cyano... And a moment later... The ply plate is correctly positioned on the wing. I need to build up behind the plate with some scrap wood before I drill out the holes for the dowels. I've alos begun the cowl today... Plan 'A' was to mount the Cowl front ring like this and build up to it... But I decided that was too fiddly! By the way, In case you are wondering, the screws have bits of fuel hose on them to make securing and removing the engine very quick at this stage! It also means that the threads will only be cut by the self tappers when the engine actually goes in properly! Plan 'B' was to build past the position of the Cowl front ring, and later I'll cut and sand back to the correct position. The glue is drying as I type! I have tomorrow off work, and it doesn't look like We will be flying, so it may well be out with the razor plane! Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted February 17, 2014 Share Posted February 17, 2014 The usual method with fixed noselegs is to bend an inverted L so that it is clamped by the bottom part of the mount and one side, though I've never been entirely happy with that as the leg always ends up getting loose as it bruises the ply bulkhead. My Kwik Fly 40 clone is done that way and is holding so far but I really miss the steering and the ability to taxi in and out easily when the grass gets longer. You really can't beat a couple of hours with a razor plane and sanding block can you? Quote Link to comment Share on other sites More sharing options...
Andy Green Posted February 18, 2014 Share Posted February 18, 2014 Signed up to follow along, There's definitely a nose under all that wood. You might find to can reduce the wriggle room required to get the engine in / out with the the prop driver removed. Andy Quote Link to comment Share on other sites More sharing options...
Peter Burgess Posted March 2, 2014 Share Posted March 2, 2014 How's the build coming along? Quote Link to comment Share on other sites More sharing options...
GrahamC Posted March 10, 2014 Author Share Posted March 10, 2014 I've got a bit behind on the build log! Time for a bit of catching up.... Shaping the nose.... And... That looks about right! Time to remark myself with a 'what will it look like when its all glued together' mock up... Edited By GrahamC on 10/03/2014 18:23:45 Quote Link to comment Share on other sites More sharing options...
GrahamC Posted March 10, 2014 Author Share Posted March 10, 2014 Just found this photo. My nose wheel solution! I asked earlier on the thread about how one stops a nosehweel from turning when its mounted between an engine mount and a fire wall. There was a helpful solution, but I decided that i couldn't adopt it without surgery.... so... I did this. When in use, the collet will slide into the hole, and a long m3 bolt passes through the hardwood insert and locks the collet. I'll hide the hole with a hatch. It should mean that it will relatively straightforward to remove the nose leg if it needs attention. Edited By GrahamC on 10/03/2014 18:43:31 Quote Link to comment Share on other sites More sharing options...
Peter Burgess Posted March 10, 2014 Share Posted March 10, 2014 One question, why not use a steerable nose wheel? And I assume that you plan to razor plane off a bit more wood. PS I would add a pic if I knew how!!! Edited By Peter Burgess on 10/03/2014 21:35:50 Quote Link to comment Share on other sites More sharing options...
GrahamC Posted March 13, 2014 Author Share Posted March 13, 2014 Nah can't be bothered with a steerable nose wheel. I don't think it will be an issue. I'm hoping it will taxy as well as my Nigel Hawes Tuccano which was amazing with a fixed nose wheel. Anyway... a few more pictures... It could be a bit rounder couldn't it? Maybe I will attempt to remove a little more wood. Adding a 'belly' to the wing. And then out with the razor plane and permagrit block Beginning to feel like I'm getting there. I felt a bit nervous about the glue joint between the horizontal stabiliser and fuselage. I don't like the fact that the stabiliser is not trapped by the fuselage top because of the way that the wood is cut for the Calibre. I decided to drop glue soaked cocktail sticks through the stabiliser into the fuselage sides to reinforce the join. Sticks cut off a little short and pushed below the surface... I'm planning to glue in the horizontal stabiliser next. Then a bit of filling and sanding, and I should be able to get the covering iron out. Edited By GrahamC on 13/03/2014 11:37:21 Quote Link to comment Share on other sites More sharing options...
Peter Burgess Posted March 14, 2014 Share Posted March 14, 2014 Have you glued the triangle piece to the rudder? Quote Link to comment Share on other sites More sharing options...
GrahamC Posted March 14, 2014 Author Share Posted March 14, 2014 Posted by Peter Burgess on 14/03/2014 11:08:10: Have you glued the triangle piece to the rudder? Ahhh. I think you mean - "Have I spotted that the rudder is two pieces?" No I hadn't spotted that! - but that explains one of the bits of wood I have left! Thanks! Quote Link to comment Share on other sites More sharing options...
Peter Burgess Posted March 15, 2014 Share Posted March 15, 2014 Glad to be of help. Another thought for you, have you any 1/2 x 1/4 strip balsa? if so then consider anti-warp strips top and bottom of the rudder. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted April 3, 2014 Author Share Posted April 3, 2014 Peter... I have in mind to top and tail the rudder as you suggest. I've had the covering iron out.... HobbyKing white and some red/pink Oracover I'm currently fitting hard points in the flying surfaces and when that's done, it will be time to cover them. Quote Link to comment Share on other sites More sharing options...
GrahamC Posted April 22, 2014 Author Share Posted April 22, 2014 A Bank Holiday means that the Calibre is ready to maiden. A managed a few finishing off touches yesterday. I ran "Clearcoat" along all the covering seams, to seal them. It seems to work well and stop the edges lifting. I took her up the field yesterday, but that was just to run the engine a bit. [Started easily the first time with the chicken stick] The general consensus was the the CofG could afford to come back a little and that the elevator pushrod wasn't ideal, so the Elevator servo has been moved to the tail. I need to find an adaptor for the spare metal spinner I have, and a club mate gave me an ARTF spinner as a stand in. I'm quite pleased with how she looks... even if the Colour Scheme confuses my Camera! [The stripes are more pink than orange] And... Quote Link to comment Share on other sites More sharing options...
Concorde Speedbird Posted April 22, 2014 Share Posted April 22, 2014 Your Camera makes it look like a blue and orange Gulf racing car! It looks tremendous, you have done a lovely job. I think it will fly brilliantly, have fun with her! CS Quote Link to comment Share on other sites More sharing options...
Jon Laughton Posted May 12, 2015 Share Posted May 12, 2015 Been thinking about one fo these for an OS75AX I have lying around....how does it fly on your ASp90 Graham? Any further comments / advice? Jon Quote Link to comment Share on other sites More sharing options...
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