Murat Kece 1 Posted April 7 Share Posted April 7 On 05/04/2024 at 17:20, Lipo Man said: The spar felt very stiff and the intention was that this takes the bending loads. It feels easily capable of that. The hope was that the skin will add the torsional stiffness - and it does feel pretty resistant to twisting. With the skin glued onto the other side it now weighs 250g - so that’s 500g for a 1.7m span wing before servos are added etc. That seems pretty good to me? Cans are earning their worth again😂! I am following with great interest.. Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted April 7 Share Posted April 7 15 hours ago, RICHARD WILLS said: Yes , but what scale is the Orange ? Could be a chocolate orange they have been scaled down while the price has gone up. 1 1 Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted April 8 Share Posted April 8 On 06/04/2024 at 18:05, Lipo Man said: Structure for the fuselage is underway. It’s big… Formers are 9mm insulation foam from B&Q, and the skin will be 6mm thickness of the same stuff. The central box structure feels very stiff - I’m going to cut some holes in the rear half to help with the CG. It feels strong enough that I think I can afford to lose some material. The orange in the photo is for scale - we’d run out of bananas… Looking great L-man, I use 3mm for cladding. I find it more than enough, is easier to form, and obviously half the weight. I use bits of 6mm if I need to support to sand down to for joins, etc. That way when It's all done you can get a nice smooth finish really easily. How are you going to join/ seat the wing? You'll need some fairly hard points if you are bolting on, and beware of the compressibility of foam. I tend to reinforce an area between the firewall and the TE with 1/32 ply so I can support a reasonable wing seat, and have something to key in a wing bolt plate and LE dowel plate. This also adds strength to the motor mount. Otherwise, glue the wing on and you won't need to worry! Graham 2 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted April 10 Author Share Posted April 10 Starting to skin the fuselage in the “Flitetest” style. Material is 6mm insulation foam, and it’s going to be pretty rough! Hoping it will look OK in the air some distance away… 4 Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted April 10 Share Posted April 10 Looks like your cladding is sagging between formers LM I get over this with stringers, either 1/4" sq balsa or 6mm x 12mm foam pieces between the formers. I used both on my Bf 109f 2 Quote Link to comment Share on other sites More sharing options...
RICHARD WILLS Posted April 10 Share Posted April 10 As Rolf would have said , "Can you tell what it is yet "? I like the way you've modelled my shed door . 1 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted April 10 Author Share Posted April 10 1 hour ago, Eric Robson said: Looks like your cladding is sagging between formers LM I get over this with stringers, either 1/4" sq balsa or 6mm x 12mm foam pieces between the formers. I used both on my Bf 109f I may do the same. Everything is just taped up temporarily at the moment, and I’m going for cartoon scale only. I’ll try another balsa bird when I’m ready to do something fancy again! This build is only intended to have a short lifespan, as I may need the motor for something else if the Warbird Replicas factory puts another shift in… 1 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted April 17 Author Share Posted April 17 Have finally got back to the Bearcat, and all the fuselage skins are roughly cut out. I will fine tune them to fit more precisely when I glue them in place, but I need to sort out the wing/fuselage fixing method first. It’s looking pretty big, but the motor is huge so I’m not currently worried. 4 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted May 16 Author Share Posted May 16 After a hiatus I'm working on the Bearcat again. Wing joiner is three pieces of foam board laminated together, with a 20mm deep piece of pine grafted into the middle piece. This slots inside the rectangular box section of the wing. Feels more than strong enough! Ailerons are now cut out and awaiting hinges, but the wings can go together for the first time. Looks like I've got a lot of wing area to cope with the weight! 2 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted May 21 Author Share Posted May 21 More progress on the Bearcat over the last few days. Next challenge was how to fix the wings to the fuselage. I've gone with two locating pins that go directly through the spar and locate in a cross member in the fuselage, with two wing bolts towards the rear. It feels pretty solid and should easily cope with normal flight loads - crash loads are, of course, a different mater entirely... I also made up the foam board empennage so I can finally put the bits together to get a feel for the size of the thing - it's a decent size! I also realised that I don't need to build the fuselage to carry out the maiden. I can fly with just the box structure internal fuselage structure to assess the flight behaviour and make any major changes if I've got thrust angle, wing incidence etc. badly wrong, and once I know it should fly OK I can skin the fuselage. Might try and get ready for a maiden this weekend. 2 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted May 21 Author Share Posted May 21 Every now and then I have a brilliant idea. Some short time afterwards, whilst completing whatever project I was working on when I had the brilliant idea, I have a subsequent moment of revelation. And at that precise moment I realise that the reason “everybody doesn’t do it like that” is because my brilliant idea has missed something so fundamental that it’s impossible to complete the project without totally undoing everything I had done after having the “brilliant idea”. Thus I find myself needing to drive both sides of the elevator on the bearcat, and not wanting to make one of those wire U shaped things to glue into the two elevator halves to link them. I came up with the brilliant (?) idea to instead make a U shaped gizmo to connect the servo horn to two control snakes. There must be a reason why this is a bad idea, but so far I’ve not managed to work it out. Someone put me out of my misery - what am I missing? Quote Link to comment Share on other sites More sharing options...
Eric Robson Posted May 22 Share Posted May 22 No. 1 does it work. If yes then it is fine. It does limit adjustment to the rear links, so make sure the outer cables are secure throughout the fuselage as one flexing more than the other will reduce travel on that elevator. It seems you have the wire straight through the servo arm which is good if it was U shaped it could cause a problem. Good luck with it but as the correct function of the elevators is important give it a thorough testing before flying. 1 Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted May 23 Share Posted May 23 I think there are a few too many variables for me. Snakes need to be secured at each end, but allowed to 'flex' to a degree in between. This is how they compensate for different amounts of expansion due to temperature changes. Any differences in length, mounting etc will mean different degrees of compensation and therefore elevator twist. For me, I think i'd keep it simple and join the elevators. As Eric said; these things are a bit important! 1 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted May 23 Author Share Posted May 23 32 minutes ago, Graham Davies 3 said: I think there are a few too many variables for me. Snakes need to be secured at each end, but allowed to 'flex' to a degree in between. This is how they compensate for different amounts of expansion due to temperature changes. Any differences in length, mounting etc will mean different degrees of compensation and therefore elevator twist. For me, I think i'd keep it simple and join the elevators. As Eric said; these things are a bit important! You’re probably right - but as this is a fairly sketchy build anyway I’m going to give them a try - and watch for any unintentional roll inputs on the maiden. On the upside it should be a very gentle flyer by warbird standards. I’ve just done a weight check with all the heavy bits included. Maiden weight (minus the fuselage exterior - I’m doing the maiden with just the core central box structure - is 2,002g. For a 1.7m span plane that seems “quite low”. 🤔 Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted May 23 Share Posted May 23 It should fly well LM. Enjoy the journey of discovery that foamboard gives you! I warn you; it's really addictive. Now I know how to scratch build practical scale models based on drawings, there's no stopping me. Spoiler alert: my next project is a 1/6 scale Bf110. That's around 108", or 2740mm in new money. Target weight is 12lbs. Should fly on a pair of 4S packs, and look suitably imposing... Graham 1 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted May 23 Author Share Posted May 23 8 hours ago, Graham Davies 3 said: It should fly well LM. Enjoy the journey of discovery that foamboard gives you! I warn you; it's really addictive. Now I know how to scratch build practical scale models based on drawings, there's no stopping me. Spoiler alert: my next project is a 1/6 scale Bf110. That's around 108", or 2740mm in new money. Target weight is 12lbs. Should fly on a pair of 4S packs, and look suitably imposing... Graham Yikes - I thought this was big... Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted May 23 Share Posted May 23 Yours is still a decent size. This is 1880mm. All B&Q foam. Flies great. 3 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted May 26 Author Share Posted May 26 (edited) Well it flies! I did a short maiden this afternoon in very blustery conditions and all went pretty well. Plenty of power on 4s, which bodes well as it will be on 6s when it's finished... CG felt good, but it climbed on throttle so I'll reduce the angle of attack of the wing a little (easy to do as the fuselage is only the central core at present...). Flight was cut short as the prop loosened - clearly I'm not used to how tightly you need to torque up a 15" prop! There was a little damage to one wing leading edge - easily fixed. So - seems it will be worth my while building the fuselage exterior! Edited May 26 by Lipo Man 6 Quote Link to comment Share on other sites More sharing options...
Geoff Gardiner Posted June 3 Share Posted June 3 Do you have a link to the B&Q foam that you are using? Thanks. Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted June 3 Author Share Posted June 3 2 hours ago, Geoff Gardiner said: Do you have a link to the B&Q foam that you are using? Thanks. Mainly 6mm sheets of this stuff: https://www.diy.com/departments/diall-polystyrene-6mm-insulation-board-l-0-8m-w-0-6m-pack-of-8/1906880_BQ.prd Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted June 3 Share Posted June 3 This stuff is good too; seems a bit easier to curl without cracking: https://www.diy.com/departments/vitrex-classic-5mm-foam-laminate-solid-wood-underlay-panels-9-76m-/5011204608997_BQ.prd 1 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted June 3 Author Share Posted June 3 32 minutes ago, Graham Davies 3 said: This stuff is good too; seems a bit easier to curl without cracking: https://www.diy.com/departments/vitrex-classic-5mm-foam-laminate-solid-wood-underlay-panels-9-76m-/5011204608997_BQ.prd I’ll give that a go - thanks. The cracking of the diall white stuff is an issue - and is less likely curved one way rather than the other. You get to recognise which side is the “top” after a while! 1 Quote Link to comment Share on other sites More sharing options...
Graham Davies 3 Posted June 3 Share Posted June 3 12 minutes ago, Lipo Man said: I’ll give that a go - thanks. The cracking of the diall white stuff is an issue - and is less likely curved one way rather than the other. You get to recognise which side is the “top” after a while! The only problem is when sanding, the inevitable remnants of UHU on your fingers makes a lovely black mess that takes ages to get off... 1 Quote Link to comment Share on other sites More sharing options...
Mike Chantler Posted June 3 Share Posted June 3 I got a recommendation for this stuff: https://technicqll.pl/en/produkt/styrofoam-adhesive-2/ More sandable than POR which seems to remain rubbery. But make sure you spread either very uniform and thin. 1 Quote Link to comment Share on other sites More sharing options...
Lipo Man Posted June 25 Author Share Posted June 25 Had a break from this project because the retracts for me Warbird Replicas FW190 arrived in the post, so I needed time to fit them then even more time enjoying flying it! Anyway, I’ve started on the exterior skin of the big Bearcat. No plans for this - it’s a trial and error fit and trim operation so a slow process and the finish will be poor up close. However, as it’ll be in the air and moving that won’t matter. The intention is a big cheap plane that looks good in the air and doesn’t need to win any scale competition prizes close up! Quote Link to comment Share on other sites More sharing options...
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