David Davis Posted March 2, 2014 Share Posted March 2, 2014 Having been very busy doing up my house over the last few months, I now find myself with the time to start building the Barnstormer Baby, at 39" wingspan, not 32" as it says in all of the literature, it is the smallest of all of David Boddington's Barnstormers. The original was a single channel model powered by a Cox Baby Bee and incorporating lots of downthrust. I shall be powering mine by a Mills 75 and fitting an elevator. With this arrangement I am told that I don't need any downthrust. Perhaps the cognoscenti would care to comment. I am also changing the rudder so that it looks like a de Havilland product of the 1930s. I am not sure whether to run the Mills with a throttle so that I may cut the engine if necessary or whether to leave the engine with its original fixed spray bar and thimble tank, taking off under full power and gliding in to land. Picture of the fuselage sides and longerons attached. Edited By David Davis on 02/03/2014 20:16:37 Quote Link to comment Share on other sites More sharing options...
Barnstormer 52 Posted March 2, 2014 Share Posted March 2, 2014 David If my maths is right the .75 is just a little bigger than the .049? I'm not sure I want to get involved in another thread about, down and side thrust For me, the down and side thrust were to lessen the power on / power off trim changes. Wouldn't you want to do that? If you can fit a throttle without compromising hugely on weight it might save you in the event of some unforeseen event. I guess, when we only had single channel control, or multi channel reed sets with no opportunity to change the trim, it was really important. I am probably silly, but I follow plans with a high degree of fidelity, other than changes in hatches etc to access the gear. As far a DB is concerned I would consider it blasphemy to change anything, but I am old. I hope to be at Greenacres, with a Barnstormer or 2. Regards Geoff Quote Link to comment Share on other sites More sharing options...
David Davis Posted March 2, 2014 Author Share Posted March 2, 2014 If I fit a throttle, I'll be flying it under power most of the time, only throttling back for low passes and to land the model and I'm 66 in just over a week! Quote Link to comment Share on other sites More sharing options...
David Davis Posted March 4, 2014 Author Share Posted March 4, 2014 Further progress on the Baby Barnstormer. This picture shows both fuselage sides joined to formers 2 and 3. The old torch is providing weight while the glue dries. I had forgotten to drill the formers before fitting them but I managed! This picture shows the formers and cabane struts in position but not yet sewn into place. Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted March 4, 2014 Share Posted March 4, 2014 Very nice David. I was particularly pleased to read "Barnstormer 52"'s post above. I thought I was the only ol' fool who actually builds vintage models to the plan! Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted March 4, 2014 Share Posted March 4, 2014 Looking good David I am not sure if the down and side thrust was something i unfortunately stirred up on my Bistormer thread by removing it all! But as you say it is needed for controlling a full throttle motor and giving similar flight characteristics to a gliding model. If you are flying electric with a throttle I don't find the thrust angles such an issue. I will be building with the side and down thrust prescribed by Boddo on the Tinker Cheers Danny Edited By Danny Fenton on 04/03/2014 09:37:37 Quote Link to comment Share on other sites More sharing options...
David Davis Posted March 4, 2014 Author Share Posted March 4, 2014 I'm going to fit a Mills 75 diesel. If I can squeeze another micro servo in there I'll fit a throttle. I'll probably incorporate some sidethrust. I hope to be able to deal with any untoward flying characteristics with the transmitter before adjusting the control surfaces mechanically if necessary. Quote Link to comment Share on other sites More sharing options...
David Davis Posted May 12, 2014 Author Share Posted May 12, 2014 Having finished doing up the house, I put it on the market just after Easter. I got an offer within ten days which I decided to accept, but the buyers will have to sell their house first so it looks as if I might just be able to attend Greenacres after all. I have been able to spend a bit more time on the Baby Barnstormer. I've now fitted the engine bearers and undercarriage, joined the fuselage together at the rear, blocked out the nose, sheeted the underside of the model and the forward fuselage ahead of the cabane struts. I have decided not to fit a throttle because the model has a 39 inch wingspan and with my notoriously heavy building it may be a bit too much for a Mills 75. By using the original tank and carburetter I should get a 2-3 minute engine run and I would hope that even my limited flying skills, I should be able cope with its flying characteristics. Note to novice aeromodellers. A tidy work station is conducive to the production of good models. Quote Link to comment Share on other sites More sharing options...
David Davis Posted May 21, 2014 Author Share Posted May 21, 2014 I have been getting on with the Baby Barnstormer. The plan shows that the cockpit area should be made out hollowed-out balsa block. I duly made a cockpit but when I used a tank cutter on it, this is what happened. So I decided to make one out of formers and sheet. This is the base of the structure, 1/16" sheet on a 1/4" frame. I'll show you the rest once I've finished it. It will be a bit different to most! I have decided to make use of as much old stuff as I can on this project, hence the decision to finish the model in old Telemaster Sales UK colours, blue and orange Profilm in my case, Solarfilm used to react to diesel fuel though I believe that the modern formulation is impervious to it. In common with many others I have used stringers on the rear fuselage top rather than 1/32" sheet. I didn't have any 1/32" sheet in stock anyway. A few details. The engine bay has received two coats of Clearcoat and I've scarfed in a triangle of 1/16" balsa between the upper longerons to increase the glueing area of the tailplane. Quote Link to comment Share on other sites More sharing options...
jolliffee Posted May 21, 2014 Share Posted May 21, 2014 Looking good - how long before you get to fly? Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted May 21, 2014 Share Posted May 21, 2014 Great stuff David. My 50" Depron Barnstormer is based on a 1/3 scale-up of the Baby Barnstormer, so it's fascinating to see yours coming together. I decided to do mine this way, rather than do a "scale-down" of the 63" version. Last year I built a "Wee Snifter" by Doug McHard, in memory of the one I built about 50 years ago. It's got rudder and elevator and a Mills .75. I can tell you that the film covering does not like the diesel fuel and I've put it on one side until I get time to strip the covering off and re-do it, probably with dope and tissue. Good luck with yours, if there is a problem it will be apparent immediately. Quote Link to comment Share on other sites More sharing options...
David Davis Posted May 21, 2014 Author Share Posted May 21, 2014 I hope to have her airbourne before the end of next week. What remains to be done is as follows: Cover and glue tailplane to fuselage Glue fin to tailplane. Make up elevators and "de Havilland" rudder, cover and fit. Fit wheels and tail-wheel. Finish cockpit and varnish. Make up servo supports and glue into place. Bolt Mills 75 to engine bearers. Fit radio and connect to control surfaces. Build and cover mainplane and fit to cabanes. Fair in cabanes and undercarriage. Having checked for warps and balance point, it should then be ready to test fly. Looks like I'll have a little more time to sort this one out. The last one I built, a Super 60 for the 2012 event had only flown once before the big day. Fortunately for me it threw it down with rain for most of the day, the engine cut after half a circuit, I glided in and went home! Quote Link to comment Share on other sites More sharing options...
David Davis Posted May 21, 2014 Author Share Posted May 21, 2014 Posted by Colin Leighfield on 21/05/2014 10:34:15: I can tell you that the film covering does not like the diesel fuel ... Yes I've seen old Solarfilm wrinkle when in contact with diesel fuel, it must be the ether. I'm told that Profilm, sold as "Oracover" outside the UK, is impervious to it. We'll see. I haven't used a diesel engine for years and the last model I had so powered was covered in nylon. PS. The original barnstormer had a 52" wingspan. Edited By David Davis on 21/05/2014 10:59:19 Quote Link to comment Share on other sites More sharing options...
David Davis Posted May 27, 2014 Author Share Posted May 27, 2014 Over the last six days I've succeeded in carrying out five of the ten tasks listed above, so I thought I'd post a progress report. Sorry about the fuzzy quality of this picture but it show my Mills P75 bolted to the engine bearers with M3 socket headed bolts (very smart!) going into captive bolts. This picture shows the component parts of my servo mountings, two pieces of 1/16" ply with a piece of 3/16" balsa in between. The idea is that you drill a hole for the servo mounting screw and the point of the screw lodges firmly into the lower piece of plywood. The completed items. I haven't fitted them to the model yet as I'm unsure where the c of g is going to be and the weight of the two micro servos might have some bearing on this. They will be glued into place once I've got the c of g right. The elevator pushrod and closed loop for the rudder are already installed. Tailplane and fin with the custom de Havilland rudder! I have covered the tailplane in silver Litespan. I haven't used Litespan much but it's come out alright and is a reasonable simulation of an aluminium doped surface. For some reason I had a bit of a block about installing the hinges on the rudder and elevator but I got on with the task earlier this morning and completed the job quite quickly. I am recycling lots of stuff on this project. The main wheels are from a collection of wheels I bought on eBay and are probably from an early Keil Kraft rubber powered kit. The tail wheel is from a Hobby King Hurricane which I crashed! This is as far as I've got. The tail is simply resting on the fuselage in the picture and the prop is just for show. I made a bit of a horlicks of bending one of the front cabane struts and the forward port strut is too short. I will remedy the problem by binding and soldering a bent piece of wire to the forward port strut so that it matches the others. Quote Link to comment Share on other sites More sharing options...
David Davis Posted June 2, 2014 Author Share Posted June 2, 2014 I started on the wing today. The main spars are an unusual size, 1/8"x3/16." I had some 3/16" square strip in stock so decided to use those. I cut out two 1/16" ply rib templates, drew round them, cut out the ribs, pinned them between the templates and sanded them to shape using my recently purchased battery sander. The first picture shows the ribs drawn onto the balsa sheet. Why do I think of sardines each time I look at this picture? Excuse the old trainers! The next picture shows the wing ribs sandwiched between the ply templates and sanded smooth with the battery sander. The final picture shows the port wing under construction. Edited By David Davis on 02/06/2014 16:34:00 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted June 2, 2014 Share Posted June 2, 2014 You're getting there David! I'm trying hard to do the same. Quote Link to comment Share on other sites More sharing options...
Myron Beaumont Posted June 2, 2014 Share Posted June 2, 2014 David Just latched on to this thread and see you are the first person to find another use for a torch other than a storage container for flat batteries .ie A weight ! Well done (wouldnt work if empty would it ?) Love the model,takes me back a few years ,especially the Mills .75 my favourite engine of all time Myron Quote Link to comment Share on other sites More sharing options...
David Davis Posted June 3, 2014 Author Share Posted June 3, 2014 Thanks for the encouragement lads. Quote Link to comment Share on other sites More sharing options...
David Davis Posted June 9, 2014 Author Share Posted June 9, 2014 With just under a fortnight to go to Greenacres I thought I'd post a progress report. Of the ten tasks listed above I've completed them all except the last three. I now have to cover the wing, install the radio and fit the 20swg hooks which secure the wing to the cabane struts. I built the wing initially as per plan. I normally transfer plan shapes to the wood using good old fashioned carbon paper but I seem to have packed my carbon paper into one of the several cardboard boxes which are beginning to fill my house prior to my moving to France. This time I've gone all hi-tech and used the photocopying function of my printer, then stuck down the photocopy onto the wood using a Pritstick. You can see in the first picture, that the wing on the Baby Barnstormer is retained by 20 swg hooks or circles which wrap round the cabane struts. This necessitates accurate bending and mounting of said cabane struts. Needless to say mine didn't line up! . So I was forced into straightening and re-bending the port rear strut many times until I got it about right. It's still very marginally out but not enough to make much difference (I hope!) The whole process was a considerable faff I assure you! If the suggested system doesn't work out I'll sew a couple of dowels fore and aft to the cabane wires and band the wing on! Sorry David! While faffing about I was envious of builders of larger Barnstormers who use prefabricated aluminium cabanes. As for the wing itself I've introduced a few modifications. Having built the wing and cut out the dihedral brace I joined the wings together. Then I thought that the half-depth dihedral brace looked inadequate, (sorry David!) so I cut out another two. One was cut out to the full depth of the main spars and epoxied into place in front of the spars and the other was cut to the full depth of the leading edge. I then added inter-spar webbing and trailing edge webbing out to the fifth bay; there are nine bays in the Baby Barnstormer's wing. These modifications resulted in a pretty rigid structure but then I had to remind myself that I was powering it with a Mills 75 and not a Super Tigre 75! Having got to this stage, wings built and joined but awaiting leading edge sheeting, I found out that the starboard wing was substantially heavier than the port one owing to poor wood selection on my part. Deciding that if I was going to have to add weight to the port wing it might as well do something, I continued the webs to the wing tip on the port wing and now it balances. Looks a bit rum but as I shall be using an opaque covering material, no-one will know! The next stage was to add the leading edge sheeting. This would have required the use of an entire sheet of 3"x36" and I began to worry about the weight of the model being too much for the little Mills so I sanded off the top spar and the wing ribs so they were flush and added riblets from scrap 1/16th balsa, sorry again David! Note the red biro from former projects! The next stage, which I'm not looking forward to, will be to make up the 20 swg hooks, sew them to the ply wing ribs and epoxy them to the centre section. Then I'll add some 1/16th sheeting to the underside of the centre section and cover the wing. As I have to visit my solicitor this morning and attend a funeral this afternoon, I can put things off until the evening! There is no indication on the plan as to what the model should weigh, so earlier this morning I chucked two micro servos, a receiver and battery into the cockpit area, stuck the wing onto the cabanes and placed the lot onto my mum's old kitchen scales. The model weighs one pound but we need to add the weight of the cockpit, (I'm doing a job on the cockpit!) and the wing covering. It has a wing area of just under 1.5 square feet. Does that give a wing loading of about 10 ozs per square foot? Will the Mills cope with this? We shall see. Quote Link to comment Share on other sites More sharing options...
David Davis Posted June 14, 2014 Author Share Posted June 14, 2014 Well it's finished at last though I did change the method of attaching the wings from wire hooks to rubber bands! The spoof civilian markings are by Tim of Model Markings, which are of excellent quality, they also arrived promptly and were priced very reasonably. I regret that I did not get the lettering right on the top wing but made a better job of the underside. The wings are covered in Litespan, a material which I've only used once before and I need a bit more practice with it. I haven't bothered with the false cylinder block, the fairings on the cabanes or the head fairing behind the cockpit. I have done this to save weight and drag as I wonder whether a Mills 75 will be powerful enough to fly a model of this size and weight. At 39 Inches it's 7 inches larger than its advertised wingspan. We will find out tomorrow! I have also departed from DB's original design by converting mine into a two seater and making use of two spare pilots I had kicking about, one from my crashed Hobby King Hurricane. Having built it I wish now that I had gone for one of the larger options. I find small models too fiddly for words, I haven't been able to find space for a switch on the fuselage side for example and the costs would not have been much greater. The larger the model, the better they fly in my experience. Edited By David Davis on 14/06/2014 21:05:26 Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted June 14, 2014 Share Posted June 14, 2014 Hi David, you got it there. Good luck with the maiden. Quote Link to comment Share on other sites More sharing options...
Phil Green Posted June 17, 2014 Share Posted June 17, 2014 Lovely job David, one point if I may... I dont like that aerial where it is, sitting between the metal cabanes... sorry! Phil Quote Link to comment Share on other sites More sharing options...
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