Mike Chantler

Simon, nice build as always 🙂 Am curious, as I'm doing a mixed carbon/foam/pla build myself, what do you use to glue pla and lwpla to the foam? Do you use the foam glue you mentioned earlier in the thread? And is it CA for pla to pla?

I usually cut the plan into big bits, wing, fuselage etc, and then cover with mylar or some other clear plastic. But a second copy always helps as some how or ever, I always end up partially destroying the original.

Fuselage is ordinary PLA except for carbon ballast tube. Wing is 75g laminating film on hotwired EPS (as I can't get EPP). You have to be carefull with the temperature of the iron!! Spars are double, full-length, 6mm carbon tube (top and bottom). Has hardwood LE and balsa sub TE with correx ailerons. Tips have ply end-caps. Think I'd change TE for thin hardwood, and swap ailerons for hard balsa. Plan and Fusion 360 model on Tim's GitHub pages (url at start I think). My Fusion 360 mods are VERY untidy - would send only via PM as they are a bit embarrassing!!

So having decided to make the fus largely out of foam I've now done a 180 degree about-face, and think I will experiment with 3d print using a 1mm shell and use the carbon ballast tube and some internal carbon reinforcement, in a similar manner to the 60" plank. Just getting a shell for the body took me a while due to my incompetence with the 3d modeller. This now needs cut up and flanged into printer-sized bits, and support added for the ballast tube..

Did manage to get into the hills last Sunday - and it flew well in moderate winds with 1/3 ballast. I forgot about looking for the tail jitter, but as I didn't notice it perhaps moving the fin back has fixed it 🙂 It could do with being a little faster - it's faster than a 45" Wildthing, perhaps slightly slower than a Gulp, and definitely looks slower than a couple of streamlined moths that were up. Wing is quite tatty now - so servo covers and tidy might speed it up a bit and have cut PW51 wing for it which I may fit in a while 🙂 One thing I did like was, despite the fact I like building, was just fitting the 3D print parts together - nice simple assembly when work is eating up your evenings 🙂 🙂

Taped old wing back and balanced at 860g which is still pretty light. All my fine ideas about refurbishing the wing, redoing the decoration etc, went out the window in the excitement of having it out again lol(!) Suspect that if I used carbon/balsa ailerons the weight would shoot up quite considerably as they are way behind the CoG as is usual with a plank. However, I'm already thinking that it would be more fun if it was more streamlined and had stiffer aileron things at the expense of weight. I have cut a couple of PW51 wings to same planform and so these may go on next incarnation 🙂 w Tail now 60mm further back so will see if this helps the yaw jitter. The linkages could definitely be lowered a couple of holes and fairings added. But very pleased with how quickly the whole thing printed and how easy it was to put together 🙂 We have a low going through tomorrow so may not get it up the hill for a while.

Ballast tube for part 3 added: Five fuselage components printed. Intrigued to know how all up weight will compare with mk2. Part 4 modified to allow fin to go further back.

2nd section now has switch fitting 🙂 and fluted front holes to allow printing with no internal structure

Am hacking the design in Fusion and printing as I go along: front tray modified to take carbon tube and 2/3AF cell pack

So plan is put holes through underside of fuselage to take a second ballast tube (and maybe do away with the wing tube if I build a second wing) A lightweight carbon tube that will take 15mm slugs will fit quite far back - but main reason for fitting it is to give strength.

So after a year of abuse and circa 150 flights or so, the nose finally gave up it's attachment to the rest of the fuselage 😮 It did have some pretty rough landings and the fastest I flew it in was 50mph gusting 60 with full ballast - main problem was me misjudging how far blown back it got, or deciding not to risk going round again and landing with quite a thump. Things I liked: - quick build and very cheap (I was try to see how cheap i could make it 😮 ) - wing is very tough - it's light (800g) with no ballast so will fly in 8mph or so - the top and bottom one-piece spars from Decathlon gave it lots of strength and stiffness - given it's speed range it got taken up every Sunday 🙂 Thinks I didn't like: - wing looks very tatty as laminating film does not shrink well after EPS has been bashed - the correx ailerons were perhaps penny-pinching cheapness carried too far(!) should of gone for reinforced balsa - has yaw jitter, maybe due to short tail moment and non aerofoil fin - needs good ballast to roll quickly (or perhaps stiffer ailerons) - no place for switch - nose coming off 🙂

So this is what happens if you don't have enough strength in a repeatedly rough-landed 3d printed slope model fuselage: Nose came completely off last week along the printlines, admittedly this plank took over fifty or so Sunday's abuse in up to 50mph winds (so it's had its share of rough and fast landings!). So spit will get the 18mm carbon tube 🙂 Have to reprint the plank fuselage now with a few mods as it's been my goto plane every week.

Progress has been very slow mainly due to work projects and good flying weather. Spent sometime looking at various fuselage solutions and decided that weight of printing whole of fus forward of CoG as I had intended is a bit heavy for our hills as adds 300g on what is quite a small plane. Also the 3d print is quite vulnerable to tension forces at right angles to print surface. So have modelled using an 18 mm OD light carbon ballast tube that will stretch right into the spinner. Spinner, next 32mm, and exhausts will likely be 3d print with rest foam. Also found some very nice 3-views at http://soyuyo.main.jp/spit1/spit1e-2.html, So am going for reasonably scale profile with mk14 tail for added stability:

Mine has steady amber when plugged in to both old and new 1A and 2A wall chargers with supplied lead. Some of my other USB leads give flashing amber (reduced charge rate?), some steady amber. 45W dell charger gives no light. Microsoft laptop charger with USB socket has flashing amber on supplied lead. Confusing! Now plugged in with amber to see how long until full charge.

Too nice outside to do much building but some gradual progress 🙂 Cut, faced and hinged ailerons Yes - am being lazy and going for very non-scale servo covers (did try homemade f3f style hidden linkages on F86 but quite a fiddle and more play than I wanted). Made servo boxes and remembered channels for cable runs (!) sanded in dihedral and glued wings:

Thanks all for raising this. I've submitted my input. Took me 30 minutes I think. Back to building.

Polyester I guess? the T33 I have has a bit of flexibility in the fuselage which helps its robustness I think 😁

Was going to use 5mm balsa for tail feathers but then discovered I'd use up quite a bit of the unwarped/nice 5mm stuff I had left. So had a look at MattyB's links and some youtube vids and decided to have a go with the mylars. Cut some cores: Just as well I cut 3 cores as I kind of jumped when pouring in the epoxy hardener (went from 30% to 60%) Thought I'd get away with it as this was just to see if 2x 125 laminating film would work for mylars. Used some food saver vac bag tube which worked a treat: But the extra hardener made the glass stick REALLY well to the laminating film despite being covered in release agent!! Quite a mess!!! lol 🙄 Tried again with correct ratio and worked well enough for first propper attempt 🙂 VID_20230826_145504.mp4 Some dimpling - but would be fixed using thicker mylars or less pressure (than .5 bar) I think. But would be good enough for light sanded deep fill primer and top coat as is I think. 🙂

Thanks 🙂 - I maybe did not use enough juice

I found it difficult to hot wire compared with eps and XPS, does it have something like glass fibre threads mixed in? And do you find that you need much higher temperature of hotwire cf eps?

Really nice 😊

While humming and hawing about the rear fus design and tail feathers, I did a little more to the wing. Sanded and filled tips. Could not remember filler mixture from last plane so wrote it down this time 🙂 20g glass is just to help hide wood grain as wings are very stiff and veneer is pretty ding resistant. And, yes, am being lazy just using WBP. Did think about using mylars/epoxy/vac bag, but got scared and used tried and tested (I would not like to build these elliptical wings again 😮 ) Putting glass on now as I warped the ailerons when i did them separately on another build with WBP.

I measured it anyway out of curiosity. With ref to the grnd pins: + rail = +5.13v Signals always 0v except when sw in 'config' mode (i.e. not 'upgrade') when port 2 signal = +4.85v. STK connected to USB nothing else connected. Don't think they are terribly expensive. Mike

PS if I can find it, I can check the power pin voltage on my STK if you want.