trebor Posted February 18, 2015 Share Posted February 18, 2015 Started putting it together and had to adjust the motor mount for my choice of motor. Didn't want to risk it on 2 bolts. Cut a piece down and welded it in place then shaped to suite. Thought I`d try to mount battery on a sliding tray for easier setting CoG but I`m not sure how far the battery might have to go back or if really needs it. Once the sides of the fuselage are glued together it will be too late. Hopefully someone might know , the instructions show it forward more but quite a few have loaded the tail with weights. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted February 19, 2015 Share Posted February 19, 2015 Hi Trebor, rather than adding weight with a sliding tray, why not put one velcro directly on the Lipo and a lonish strip in the fuselage, then you can adjust the CoG and add very littw weight As for CoG then remember "A Nose heavy plane fly's badly, a tail heavy one once" Quote Link to comment Share on other sites More sharing options...
Caveman Posted February 19, 2015 Share Posted February 19, 2015 Trebor, neat job with the motor mount, that should do the job nicely! Ref. the battery mounting, I can see where you're coming from, but, I think it's probably an elegant but over-engineered solution. Here's a few photos of mine The interior without the battery - I've stuck two pieces of velcro onto the fuselage floor. I've drawn a red line to show the front of the battery for correct CoG. The battery with two corresponding velcro pieces attached. Using this method the plane can be thrown about the sky, fly inverted and do any acrobatics you like, and the battery has not come loose once! The interior with battery installed. Note there's not a lot of spare room. The installation of ESC and receiver - I stuck a length of 1/4 sq. spruce across the rear of the motor mount and fastened the ESC to that with a cable tie. This is to prevent the ESC and wiring coming into contact with the motor can. The receiver is fixed with velcro. Wires leading to the wing, elevator and rudders servos are stuck to the fuselage sides with micro-porous tape, otherwise they get in the way when installing and removing the battery. I had to add weight to the tail, despite the battery being far back in the fuselage. I cut a slot on the underside, just in front of the tail feathers, where the fuselage is quite 'meaty', slotted in some lead and secured it with micro-porous tape. It's not very pretty, but it does the job, can't be seen and it easily removable should adjustment be needed. I'm not suggesting this is how it should be done, but it works well for me and is a simple solution. Hope that helps GDB Quote Link to comment Share on other sites More sharing options...
trebor Posted February 19, 2015 Author Share Posted February 19, 2015 Is your battery touching the rear of the compartment and how much weight did you have to put in ? I was just trying to get enough movement on the battery so I wouldn't need any weights. Quote Link to comment Share on other sites More sharing options...
Caveman Posted February 19, 2015 Share Posted February 19, 2015 Trebor, my battery is positioned so that the rear is up to the hole in the lower fuselage. If it were to be further back it would be more awkward to insert and remove, obscure the vent and would make no significant difference to the CoG. I have inserted 47 grammes of lead in the rear fuselage as per my earlier photo. However, the amount needed will depend on the weight of your motor etc.. GDB Quote Link to comment Share on other sites More sharing options...
trebor Posted February 19, 2015 Author Share Posted February 19, 2015 My motor is supposed to be 115g but the spec's have changed a bit as it's now got a 5mm shaft instead of 4mm. With it mounted on the plate with hex bolts it's 132g. I could slide my battery all the way back as its raised off the floor so ventilation wouldn't be a problem. I was going to put the Esc on the floor under ply tray and the Rx under wing in vertical hole. Quote Link to comment Share on other sites More sharing options...
Tim C Posted February 19, 2015 Share Posted February 19, 2015 With a 115gm motor a 2200mah 3S battery is as far back as it goes, with a 3000mah 3S Battery probably 20mm from the rear bulkhead Quote Link to comment Share on other sites More sharing options...
Matt Jones Posted February 19, 2015 Share Posted February 19, 2015 This can't sound anything other than unbelievably geeky but................... That's some of the best welding I've ever seen Quote Link to comment Share on other sites More sharing options...
Caveman Posted February 19, 2015 Share Posted February 19, 2015 My motor, Emax BL2815/09, is, according to their website, 112g. My battery is 3S 2200 20C and I still needed 47g lead at the rear end to achieve the correct CoG. I can't see anything wrong with your sliding battery mount, provided there is some means of securing the battery to stop it moving forward and upwards! I'm afraid that at the end of the day the only way to find out if you need lead at the rear, and how much, is to finish the plane and then balance it. The Funcub is able to carry a bit of extra weight without any problem, so 10 or 20 grammes here and there isn't an issue. GDB Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 19, 2015 Share Posted February 19, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
trebor Posted February 19, 2015 Author Share Posted February 19, 2015 I might try sticking the fuselage together with tape and do a dummy run before I stick it, I could slide the battery back into the next compartment. Quote Link to comment Share on other sites More sharing options...
trebor Posted February 21, 2015 Author Share Posted February 21, 2015 Had a bad night, I'm now looking for a new set of wheels mine melted, please don't ask how. I don't want to talk about it, I'm putting the kit to one side now till I calm down. Quote Link to comment Share on other sites More sharing options...
Former Member Posted February 21, 2015 Share Posted February 21, 2015 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Tim C Posted February 21, 2015 Share Posted February 21, 2015 Trebor, PM me, I have a used set you can have for the cost of postage, I upgraded to a pair of HK rubber wheels Quote Link to comment Share on other sites More sharing options...
trebor Posted February 21, 2015 Author Share Posted February 21, 2015 Thanks Tim, I've sent a reply. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted February 21, 2015 Share Posted February 21, 2015 Trebor, you quietly slipped in some rather remarkable (certainly to me) metalwork at the top of this thread. Could you possibly expand on the welding technique, equipment and materials used? I'm sure there are more than just me who would be very interested. Quote Link to comment Share on other sites More sharing options...
Stevo Posted February 21, 2015 Share Posted February 21, 2015 "Trebor, you quietly slipped in some rather remarkable (certainly to me) metalwork at the top of this thread. Could you possibly expand on the welding technique, equipment and materials used? I'm sure there are more than just me who would be very interested." YES PLEASE! Quote Link to comment Share on other sites More sharing options...
Tim C Posted February 21, 2015 Share Posted February 21, 2015 Trebor, In answer to your question on painting the Funcub, Its Dulux Tester Pot in International Orange, theres more on a previous posting. http://www.modelflying.co.uk/forums/postings.asp?th=69260 The Decals are one of a number of Funcub conversion Kits I sell, I recently added SuziAir and Widerness Air kits, both these go on a white, so no need for paint Quote Link to comment Share on other sites More sharing options...
trebor Posted February 21, 2015 Author Share Posted February 21, 2015 The weld was in fact brazing, I've had it for years, last time I used it I repaired some motorcycle front alloy forks. All you need is a hot flame, but not too hot !! Something like a gas soldering iron for small stuff or your normal blow lamp with a small flame but it depends on the size of the piece as alloy dissipates heat really quick. It's similar to silver soldering but no flux required. HST - 2000 flux less brazing rods, small wire brush, heat and just use the rods to spread / encourage it to flow into prepped area. The bit I put in was real aluminium, not sure about the motor plate. The rods melt at a lower temp to aluminium but it's stronger. File off followed with wet n dry. Practise first as you can easily turn your aluminium into a round blob of metal. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted February 21, 2015 Share Posted February 21, 2015 Thanks Trebor, I'd never heard of those rods but they're easily found on ebay. I'll just have to remember now. Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted February 21, 2015 Share Posted February 21, 2015 Posted by trebor on 21/02/2015 21:41:08: The weld was in fact brazing, I've had it for years, last time I used it I repaired some motorcycle front alloy forks. All you need is a hot flame, but not too hot !! Something like a gas soldering iron for small stuff or your normal blow lamp with a small flame but it depends on the size of the piece as alloy dissipates heat really quick. It's similar to silver soldering but no flux required. HST - 2000 flux less brazing rods, small wire brush, heat and just use the rods to spread / encourage it to flow into prepped area. The bit I put in was real aluminium, not sure about the motor plate. The rods melt at a lower temp to aluminium but it's stronger. File off followed with wet n dry. Practise first as you can easily turn your aluminium into a round blob of metal. And I am quite sure its not as simple as that makes it sound! Quote Link to comment Share on other sites More sharing options...
Geoff S Posted February 21, 2015 Share Posted February 21, 2015 What ever else you do make sure the battery is well secured with more than just Velcro on the bottom. My battery did a bunk half way through an outside loop and the airframe gently floated down inverted with me still fiddling with the transmitter sticks even though I knew there was no battery The Cub survived almost undamaged but I had to replace the cowl. I try to avoid taking off or landing on our Tarmac runway and use the grass to avoid wearing out the foam wheels. They've survived probably 100s of landings and touch and goes. Geoff Quote Link to comment Share on other sites More sharing options...
trebor Posted February 22, 2015 Author Share Posted February 22, 2015 Posted by Tim @ ModelMarkings.com on 21/02/2015 18:09:01: Trebor, In answer to your question on painting the Funcub, Its Dulux Tester Pot in International Orange, theres more on a previous posting. http://www.modelflying.co.uk/forums/postings.asp?th=69260 The Decals are one of a number of Funcub conversion Kits I sell, I recently added SuziAir and Widerness Air kits, both these go on a white, so no need for paint Question for you Tim, I looked at the Dulux tester pots of paint, would the bathroom hardwaring paints need varnishing as they can take a good scrubbing and are good with steam anyway ? Quote Link to comment Share on other sites More sharing options...
Tim C Posted February 22, 2015 Share Posted February 22, 2015 I have never used Bathroom paint on foam, so no idea, in theory yes. The benefit of tester pots is you can get Dulux mixed to virtually any colour in 250ml pots, but only in Matt, you can use matt, satin or Gloss water based varnish to finish, hardwearing and you can vary the finish as to what you need., I recommend mini foam rollers or spray, I have both used a full sized touch up gun or airbrush with .5 needle. B&Q switched to Valspar, and you can only get paint mixed to RAL codes plus their own, but I do understand you can get sample scanned to get a match, never tried it though, Dulux mixers accept RAL, NCS, BS and other std paint codes, and it pretty easy to get a colour from the net in RGB converted to a paint code Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted February 22, 2015 Share Posted February 22, 2015 Yes B&Q will scan a colour swatch and mix it for you, you have to suffer the raised eyebrows when you say its for a tester pot but its a small price to pay! Quote Link to comment Share on other sites More sharing options...
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