Mark Elen Posted December 31, 2015 Share Posted December 31, 2015 Hi All, Just thought I'd start my build log, but its going to be a week or two before I get started properly, as I'm still finishing off the RM Trainer that I have on the go at the moment. I've got all of the materials in stock and have had the plans copied ready to start. I know Peter has used balsa for the spars, and I appreciate that he has done some testing with another model, but I'm going to be using something a little harder, as my first ever build met its demise due to poor balsa selection for the spars - all my own fault, but I still prefer to err on the safe side. Anyway, a build log isn't a build log without photos, here are a couple of mine to get started: I'm really looking forward to this, as I've never had a model with a pilot in it..... Also, its my first go with a four stroke, something else I'm looking forward to. Cheers Mark Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted December 31, 2015 Share Posted December 31, 2015 Spruce spars for me Mark, I usually have a lady pilot in mine, they're better flyers as long as your fields not near a shoe shop John Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted December 31, 2015 Author Share Posted December 31, 2015 Nice one John, made me chuckle... Regards Mark Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted December 31, 2015 Share Posted December 31, 2015 Yes, if you are going to use balsa for the spars it does need to be hard. A lot of sucessful models with balsa spars and of course Peter knows what he's doing. Spruce is good for spars - and much stronger, but of course you do have a weight penalty. And it may not be necessary for a model like this - unless of course you like the added security. There are other ways of adding strength to the spar assembly than upgrading the material and, given the power levels I'm planning for mine and the way I like to "throw them around" a bit, I will be at least considering some of them in my build - when I get to the wings! BEB Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted December 31, 2015 Author Share Posted December 31, 2015 Thanks BEB, It's just a bit of peace of mind, I've not decided what I'm using yet, I've got Spruce, Cyparis and Bass in stock, so I may have a weighing session before I make the decision. Thanks for your comments and Happy New Year Cheers Mark Quote Link to comment Share on other sites More sharing options...
Gazza58 Posted January 6, 2016 Share Posted January 6, 2016 Hi Chaps, I have made a start with the fuselage and am turning my attention planning wise to the wings. I have both 1/4 balsa and spruce on my stock shelf and am considering what to use as spars. My question is should all three spars be spruce... or just one or two. Its been a looong time since I used spruce and this model will address that on wings and fuselage. The 1/4 balsa is not particularly hard and obviously there are three of them with webbing between both. I ask this only in the light of building a Tomboy Senior with the single spar as shown on the plan. It lasted about 3 minutes before clapping hands and plummeting to Earth in a spectacular way. I have now built a new wing for it which is much stronger. I would like to avoid this with Ballerina Best Regards Gazza Quote Link to comment Share on other sites More sharing options...
AVC Posted January 6, 2016 Share Posted January 6, 2016 Hi Gazza Probably the designer is the best person to answer, but I don't think you'll have problems with three spars, even if the three of them are balsa. You may use spruce, but in my opinion this would only add unnecessary weight to the wing. As long as the whole structure (sheet, spars and ribs) is built accurately, the resulted wing will be strong enough. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted January 6, 2016 Share Posted January 6, 2016 As I suggested above Gazza, I feel that hard balsa, allied to the shear webbing and the leading edge sheeting forming a D-box, should be strong enough for this model - unless you're planning on flying it 3D! Yes spruce is stronger, but its also heavier! If you go for a combination then you need to make the upper and lower front spars connected by the shear web out of the same material really (whatever it is) so that the whole assembly flexes together as one unit. If you just make one of them spruce and the other balsa then, as spruce is much stiffer, it will end up taking most of the load - and that could be weaker than two hard balsa spars working together! BEB Quote Link to comment Share on other sites More sharing options...
Gazza58 Posted January 6, 2016 Share Posted January 6, 2016 Thanks Chaps, BEB... That is precisely the reason I asked about mixing Spruce with balsa. (Cross ply & radial on the same axle). In all honesty I am not sure if we worry a little too much about weight in an instance like this where the difference is but a few grammes. A large wing like this will easily support such minor weight differences. Indeed I believe that Ballerina will fly with a considerable weight strapped to it. Nevertheless, I am trying to build the model as light as I can whilst still ensuring structural integrity. I saw Peter mention that rock hard balsa spars are needed if not spruce. I can see that it makes sense to use all spars from one material. I looked for 'rock hard' balsa and found nothing even close. I am thus leaning toward spruce at the moment, unless I can be persuaded otherwise. Thanks again for your thoughts Gazza Quote Link to comment Share on other sites More sharing options...
Gazza58 Posted January 6, 2016 Share Posted January 6, 2016 What's 3D...? I can just about keep it airborne Quote Link to comment Share on other sites More sharing options...
Former Member Posted January 6, 2016 Share Posted January 6, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
AVC Posted January 6, 2016 Share Posted January 6, 2016 Posted by Percy Verance on 06/01/2016 15:46:43: Oh, and in answer to your question regarding what 3D is. It's when someone has a model plane Gazza, when they really ought to have bought a helicopter...... Happy Landings......... This is one of the best definitions of 3D I've read! Quote Link to comment Share on other sites More sharing options...
Gazza58 Posted January 6, 2016 Share Posted January 6, 2016 Hi Perce, Thanks for your input. I'll go lookout some cyparis at the lms. I'm only relieved that I didnt turn up at the patch with a pair of 3D glasses....... Gazza Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted October 2, 2016 Author Share Posted October 2, 2016 It's about time I got my finger out and started this build. So today, I have cleared my bench and got the plans out... Got this little beaut to go in too. Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted October 2, 2016 Author Share Posted October 2, 2016 Well, I've finally got started. Got the ply cut to size + 1mm to allow for sanding to final size and the 1/8 formers cut and glued ready for shaping. It feels good to finally make a start. 😁 Quote Link to comment Share on other sites More sharing options...
AndyD Posted October 2, 2016 Share Posted October 2, 2016 nice to see the ballerinas are still being made,is the rm trainer ready for flight,im building a electric version which is ready for covering,nice engine for the ballerina,mine might be converted from electric to glow soon as ive lost a lot batterys lately. Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted October 2, 2016 Author Share Posted October 2, 2016 Hi Andy, Yes, the RM Trainer is finished and flies beautifully. One of the guys at my club bravely offered to maiden it for me back in March - I've not flown fixed wing for about 8 years. A few clicks of trim and it flies great. Unfortunately, due to work and other commitments, yesterday was the first time I got to get out with it since. Managed about 10 flights and I'm getting back into the swing of things. It's spurred me on to get started with this build. I'm an IC kind of guy, but I really don't like the messy cleaning up after. The other guys at the club yesterday were all leccky, and I was kind of jealous of the pack it away clean that went with it.... Cheers Mark Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted October 2, 2016 Share Posted October 2, 2016 Not a lot of mess with the Saito Mark Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted October 2, 2016 Share Posted October 2, 2016 They still have to clean the dead flies off the leading edges and wind shield though! The cleaning process with I.C is also a good and essential time to check for damage and any maintenance needed before the next flight. Something often missed with electric! I was out flying my Ballerina this afternoon in another session of balance adjusting to move the CoG further back to make it more agile like John Stones model. I was also messing with the flying speed and was very impressed with just how slow she could fly without loosing height. Lots of low and slow and touch and go's. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted October 2, 2016 Share Posted October 2, 2016 It's a Ballerina it's supposed to be light on it feet Quote Link to comment Share on other sites More sharing options...
Chris Barlow Posted October 2, 2016 Share Posted October 2, 2016 Sorry, but I just had to....... Before CoG adjustment! lol Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted October 3, 2016 Share Posted October 3, 2016 For some reason I never saw this Build blog. As for the spars. I always specify "rock hard balsa" A wing with identical structure has been tested in the air at 24.8G which meant that the model weighed 95 lbs for a second or so. THat was on a similar sized model with more power. Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted October 3, 2016 Share Posted October 3, 2016 Posted by Chris Barlow on 02/10/2016 23:14:42: Sorry, but I just had to....... Before CoG adjustment! lol Ah! A Grumman fighter!!! Quote Link to comment Share on other sites More sharing options...
kc Posted October 3, 2016 Share Posted October 3, 2016 If you cannot get spruce or hard balsa for the 1/4 sq spars then B&Q often sell 6mm sq softwood in 2.4 M lengths. This seem a good substitute as the 8ft I have weighs one and five eigths ounces compared to one and a half ounces for the 8ft of balsa. However be careful - the B&Q stuff sometimes may not be straight and its 'finger jointed' if you look carefully so you don't want a joint near the centre of a wing. Choose a straight length with straight grain, that has few joints and is a constant size along it's length. Of course it's nominally 6mm not 1/4 so if you have laser cut ribs the 6mm could be a loose fit. No problem if you cut your own ribs to 6mm. Finally it's 2.4 metre lengths which is a little shorter than 8 ft ( by 1.5 inches roughly) so you need extra. Take a tape measure and a saw so you can saw it into exact lengths if you need to shorten to fit in the car. Buying cyparis or spruce from a model shop is probably better and no dearer but if you cannot get the proper stuff consider the B& Q alternative.. Quote Link to comment Share on other sites More sharing options...
Mark Elen Posted October 12, 2016 Author Share Posted October 12, 2016 Bit more done tonight. Starting with my way of gluing Fuz doublers. I cut out the doublers and match up the curves, then carefully lining up both Fuz sides and the slightly oversize doublers, I drill through all 4 parts. Then on with the impact adhesive, use a couple of short lengths of 2mm piano wire to line up, push down, then lock the 2 sides together with collets and sand just the doublers down to match up withe the 2 Fuz sides. A little bit more to do in that last photo around the wing root, but it's nearly there. Then just the rears to do. Cheers Mark Quote Link to comment Share on other sites More sharing options...
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