Djay Posted February 7, 2014 Share Posted February 7, 2014 After the successful test flights of my first own design I started straight on my second. A raid on my spares box uncovered an OS 25 fx spare so a 25 size design was sketched out and drawn up. Bulkheads drawn up parts cut out ready for fuse build construction then started Darryl Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 fuse continues Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 nose area fuse sheeted start on engine cowl Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 wings started Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted February 7, 2014 Share Posted February 7, 2014 now that looks good sir. you have the bug now i take it. Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 wings continue wings sheeted and fuse snakes installed cowling cut out for engine clearance fuse sheeting finished Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 wing mounting points fitted tailplane parts cut out tailplane fitted ready for covering top of wing covered Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 bottom of wing start of fuse covering temp u/c fitted nearly finished Edited By Djay on 07/02/2014 13:41:53 Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 given a name servos and radio installed ready for test flight Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 well first a bit of info about the model span is 42 inches with a 9 inch chord, modified flat bottom rib section. 6oz fuel tank OS 25fx engine weight unknown, but is very lightweight. Named Mojo, for reasons unknown to me. It was designed to have retracts but for the test flight I made up a temp u/c but unfortunately it is mounted to far forward. On the take off runs the plane just kept ground looping and trying to attack the photographers filming the test flight. After about 4 attempts I managed to lift off and get the plane high enough to trim out. It needed lots of up trim and just a click of left trim. The plane then flew superbly, very comfortable with it. Inverted flight showed C of G to be spot on as just a minimum of fwd stick pressure required. The spectators said it is very fast, but to me flying the model it seemed slow. Once the retracts are fitted I will install a tuned pipe as well and then experiment with props. So 2 weeks exactly from test flight of my 1st own design, to 1st test flight of my second own design. One problem was the amount of up trim required, but as the tailplane is fixed I will have to adjust the incidence of the wing, so correct me if I am wrong but the L/E of the wing will need to come down, or the T/E raised a bit to compensate to get the incidence correct. So now own design number 3 has been started already. Darryl Edited By Djay on 07/02/2014 13:36:59 Edited By Djay on 07/02/2014 13:44:29 Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted February 7, 2014 Share Posted February 7, 2014 wow nice looker. Quote Link to comment Share on other sites More sharing options...
Masher Posted February 7, 2014 Share Posted February 7, 2014 Darryl, that's a good set of posts and the final result has good clean lines. I've not tried own design yet but this thread encourages me to try, thanks! How long was it roughly from idea to completion? Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 Hi Masher. it is really easy to design your own if you use Peter Millers guide that was in RCME. you just start with a horizontal line on the page, then on the left draw a vertical line for your datum, this is the back of the prop roughly. Then measure the required engine and mount length and draw another vertical line, this will be F1, then measure tank length and this will be F2, and wing L/E, work out your wing chord and draw a vert line this will be wing T/E, F4, F3 will be halfway between the two roughly. Then wing chord length plus a bit, along draw another vert line this will be stab L/E, couple of bulkheads can go in-between. then after working out the chord of the tailplane this will be last vert line and end bulkhead. Now all you do is get a pencil and sketch in the fuse lines using the horizontal line as the fuse top, or fuse center line, or fuse bottom, Wing chord and tailplane chord can both be on this line, or one above and one below, as long as you have them inline or parallel to this line. fuse width will be dictated by engine mount size, tank size and servo size as a minimum. Sounds complicated but it is very easy . Use other plans to work out dimensions and ideas, but do not copy direct as then it is not your design, just measure. I also sketch designs using the above on A4 paper, draw a horizontal line add a wing rib shape somewhere and doodle in fuse designs. Give it a go. Once you have the rib and fuse shape it is easy to cut a set of parts and it is then no different to buying a kit. Darryl Edited By Djay on 07/02/2014 14:01:31 Quote Link to comment Share on other sites More sharing options...
Masher Posted February 7, 2014 Share Posted February 7, 2014 Thanks Darryl I thought I recognised some of the "Peter Miller Method" in your design procedure, I bought his book and was going to use that same approach. It's funny, when building from plans, or even ARTF's, I seem to get hung up on getting everything right to the instructions but there is really no need. Where's my pencil............ Quote Link to comment Share on other sites More sharing options...
Nev Posted February 7, 2014 Share Posted February 7, 2014 Hi Djay. I like this one, very slick. If you don’t mind me saying so much nicer looking then your first. But you are way ahead of me, I’ve started a couple of designs but not got as far as cutting any balsa. Great model, nice one. Quote Link to comment Share on other sites More sharing options...
Djay Posted February 7, 2014 Author Share Posted February 7, 2014 thanks guys. The first one though not much of a looker is the best flying model I have flown in over 30 years. So nice and easy to fly, and today I was flying whole circuits knife edge, the plane just sits there on its side and flies quite happily. It is capable of far more than I can do . this 2nd one was designed for speed and once completed should hopefully be just as nice to fly. Darryl Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted February 7, 2014 Share Posted February 7, 2014 Well Done , that is one very nice plane you have made there . Quote Link to comment Share on other sites More sharing options...
Pete B Posted February 8, 2014 Share Posted February 8, 2014 Really nice job there, Darryl - if they all flew straight off the board it wouldn't be a challenge, would it? Any chance of a video when she's sorted? Pete Quote Link to comment Share on other sites More sharing options...
riverlandgirl. Posted February 8, 2014 Share Posted February 8, 2014 Good stuff, and a satisfaction that's hard to beat! Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted February 8, 2014 Share Posted February 8, 2014 Hi DJay, I like both, but how do you obtain the rib shape to give you what flying qualities you require. The 2nd model you say is" fast", is this due to wing thickness etc ? Cheers Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted February 8, 2014 Share Posted February 8, 2014 Very nice Daryl, I like it Quote Link to comment Share on other sites More sharing options...
Djay Posted February 9, 2014 Author Share Posted February 9, 2014 Hi Flyboy, the first one was a guess really, I used a modified flat bottom rib shape, once I worked out the chord size I just drew up a rib shape using other plans as a guide and drew it to fit. The second one I shrunk it to fit and it worked out just right. just the right thickness to fit servos and retracts in the wing. I did not do a symmetrical rib as I am sill unsure of the shape and the performance characteristics of the different ribs plus I wanted to retain good slow speed performance for landings. Though to get a symmetrical rib just cut the flat bottom rib in half and flip the top half over to get the bottom., My next model has an enlarged version of the same rib as it seems to be performing perfectly well for general usage. Best thing is to look at other plans and work out what you want and just draw one out, if it looks right then it will probably work ok. for me it is all guess work, Main spar goes at the highest point of the rib, which is aprox 25 - 30% of the chord, and this will be your C of G position. If required rear spars can be added for strength. Darryl Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted February 9, 2014 Share Posted February 9, 2014 owned a Kyosho Oxaly's, flew great but covering kept coming off lining paper and a ruler ended with this, flies well and coverings still on im with you Djay, have a go its very enjoyable Quote Link to comment Share on other sites More sharing options...
fly boy3 Posted February 10, 2014 Share Posted February 10, 2014 Thanks for the info Djay, I like it. I suppose a thicker wing section equates to a slow flying model and a thin one to a faster flier. ? I do like John Stones model too. Perhaps I will give it a go some time. Cheers Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted February 10, 2014 Share Posted February 10, 2014 Posted by Djay on 07/02/2014 13:26:02: One problem was the amount of up trim required, but as the tailplane is fixed I will have to adjust the incidence of the wing, so correct me if I am wrong but the L/E of the wing will need to come down, or the T/E raised a bit to compensate to get the incidence correct. Djay, if you needed up trim, I would suggest that you need the L/E of the wing raising? Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.