Andrew McKelvey 1

I tend to use old bicycle spokes which are about 2mm, or just less so I’m not limited to 300mm, run a threaded die up it and you can have a thread both ends, nylon clevises don’t seem to care whether it metric or ba, you just need to source some old wheels. The bent end is good in servo horns you don’t need keepers! You can join the ends using 5 or 10amp electrical connectors (chocolate blocks) if you don’t want to go to the hassle of rethreading, annealing the end helps with cutting new threads Edited By Andrew McKelvey 1 on 18/08/2020 10:58:10

I was beginning to wonder where my copy was, my subscription according to the website expired last month but as I pay quarterly I see it is now October so my guess is I am ok their. However I did discover I can read the current mag online through the subscriber pages so I have had a good browse all ready, just would rather have copy in my hands to flick through and the print is bigger!

Basically I have gone for this as a design looks like most other wings I've ever seen. I have gone for 11 wing ribs with 45mm gap at the root (3 off) one actually sit over the fuselage, the gap is 65mm otherwise, they are all 3mm ribs with 6mm cap strips. It is D section sheeted leading edge with 1.5mm shear webs, spars are 6mm balsa. I haven't decided on aileron construction because it isn't stock size 48mm. Also I haven't made my mind up to make it two piece with a joining tube or one piece, its about 620mm each panel. I have also redrawn the section and gone for a 14% depth S8035 section, the idea was to go thick because I didn't want a ballistic missile just something that potters about, but would pull the shapes but nice and slowly. A sort of cross between a Wot4 and a Ripmax Jive if there can be such a thing, however I haven't got the resources to test every little change, spose I could make a thick one and a thinner one! I am surprised there isn't more science to this design malarky just seems to be preference and what has gone before and it's if it looks good it should be ok Any thoughts Edited By Andrew McKelvey 1 on 06/07/2020 17:16:02

I am designing a sport model which will initially be about 52" wingspan and I have decided to use a built up wing rather than a foam core one, cutting foam cores is hard work on your own! I haven't any foam and I'm not going out, got loads of balsa. So the question arises for a wing that will be about 620mm each panel and about 300mm constant chord with full length ailerons give or take the bit in the centre and about 15% depth, how many wing ribs would you build into the wing. Had selected a NACA 0015 or 0018 section. I was thinking something like a Wot4 built up wing but as I don't have one I cant count them. Is there a rule of thumb I don't know about it looks to me the spacing can be as small as 50mm and as large as 80mm for this size wing, my Panic Bi Plane has them closer at the root and further apart at the wing tips. Any thoughts?

I get there eventually

It is always a bit difficult knowing when to reply to one of your posts because I think it deters people from then adding their weight behind the thread. However, I thank those of you have responded and I take on board all the comments, the bec issue I summarily got 4max view on the subject when I perused the site last evening and conclude that I will disconnect a +ve from one of the esc, in fact depending upon where the cd comes out I might just disconnect both and power the receiver via a nimh in the nose if it needs some weight. When designing a scratch built it is interesting how many decisions have to be made some will affect the flying ability and some become aesthetic, like the above thread it is some times nice to have some one else's thought when you in the shed.. just to confirm your own thoughts or the opposite. My intension is to do the normal preliminary checks put it on the strip and let it go and see what happens, most things I can probably compensate for on the sticks but if I wreck it I'll get some practise repairing a foam board model, what can do wrong! Ps I did take some photos but do not seem to be able to add them here keeps asking me to browse a library which means nought at the moment

Long Story severely shortened. I have designed my own twin engine high wing plane which I am calling a cartoon scale Bristol Freighter, only because it has roughly the same bits in the same shape but not necessarily exactly the same size. I wanted to have a go a building a model with foam board using simple building techniques and see what I ended up with. The dimensions roughly the same as a single engine high winger I 'inherited' and put back in the sky. I have a couple of questions still nagging in the back of my mind which someone in the know might answer for me. I am using two brushless motors with two esc and one battery and I had it in the back of my mind I am supposed to isolate the live from one 'BEC' so It works, well I didn't initially and it does, in effect the bec's from both esc is feeding a regulated 5v to the receiver, I was told I had to isolate a +ve from one so it didn't confuse the esc? the receiver? So first question why do I need to isolate one of the supplies from the esc's because both mine work ok without. I must be missing something. The motors are configured one to run CCW and the other CW does it matter which wing they are mounted on? At the moment neither has any side thrust they both point straight ahead so do they need side thrust and if so in which direction? Lastly the wing the engines are mounted on is Clark Y because of simplicity as it is made from blue foam. The flat bottom has zero incidence with the tail plane so in effect aerodynamically they will have a couple of degrees down thrust. The plane this model is based on has exactly the same setup and flys quite well ie little or no side thrust and only a cople of degrees down thrust on the engine, clark y wing bottom at zero incidence to the tail plane. I would be interested in your thoughts otherwise I just put it down on the strip when the wind subsides and open the throttle and see what happens. Think I might take a few photos for you

Colin Not sure you remember me but we exchanged emails a few years ago regarding a PFM Team Special which I still haven't built but still on the wish list to kit. As you can guess I am a bit into 70's 80's models Edited By Andrew McKelvey 1 on 15/10/2016 18:57:21

Thanks for the feedback guys I Was never intending using the props I stated they where what was on the plan, I am flying a Bowers Fly Baby at the moment on a 91FS using a 13.5 x 8 which is about 4 kg and it takes off nicely on half power and will go vertical for ever on full bore, just not scale like though. I just got to wondering if it would be OK for the Zlin which is 82" wingspan so I'm guessing it will be, I do have a 120 FS but that would mean butchering the cowl to get it in, which I don't really want to do. The watts per pound comes from sizing leccy planes that's all, which I thought might transfer to ic models

I am in the process of completing a Pat French Giant Zlin and began thinking about the engine size and wondering if the chosen one would be enough. I had built it confidently with an ASP 91FS installed inverted, then I began wondering if it would be enough to give scale aereobatic performance, the recommended prop size on the plan 13x5 or 12x6 so the 91 will swing one of those easily. The thought process wondered what does the real thing fly on and I was surprised to find that it has a 158hp engine and max AUW of just less than 1700lbs which works out to 69 Watts per pound! My model weighs a little more than the plan weight and with a 91FS tips the scales at just shy of 5kg and that would give 118 watts per pound. With a 120FS installed the weight would be 5.2kg and that would be about 138 watts per pound. I also considered a 91 two stroke with a tuned pipe which would get us to 196 watts per pound but I might have noise issues with that. Any way you look at it this looks to me to be far more power than the full size had available So which is it to be or am I misguided in my theory