Sylvain Le Gall Posted March 6, 2013 Share Posted March 6, 2013 Hi all, Just wanted to share my new 'instant' project. A quick build small Twin EDF delta jet. Here are the features I have been thinking of: - Small size jet all balsa (maybe depron, I'll figure it out...) - Delta wing for low wing loading and 2 micro servos - Twin EDF for fun (50 mm, on 4S 2500-3000 mAh) - Flat wing profile ! (that would be a first for me !) - No landing gear - Wingspan is 70 cm and lenght 90 cm - Weight should be around 1000 g (I've been conservative on my calculation, though) Here are the first draws : With the way I designed the Mini jet, it should take no more than a few evening to build it ! Every comment will be appreciated ! Edited By Sylvain Le Gall on 06/03/2013 21:51:58 Quote Link to comment Share on other sites More sharing options...
Richard Harris Posted March 6, 2013 Share Posted March 6, 2013 If it looks right then there is a good chance it will fly right.....looks good to me Rich Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted March 6, 2013 Author Share Posted March 6, 2013 Rich, your comment could not be more appropriate ! Marcel Dassault used to say 'Un bel avion est un avion qui vole bien'...maybe you have noticed the famous 'Mirage IV' inspiration in my drawings... Edited By Sylvain Le Gall on 06/03/2013 22:20:30 Quote Link to comment Share on other sites More sharing options...
Tim Hooper Posted March 6, 2013 Share Posted March 6, 2013 I did think 'Mirage' the moment I saw it! Good luck with this one. tim Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted March 12, 2013 Author Share Posted March 12, 2013 Hi, Finally build the fuselage in a couple of evenings. It is 55g less than I had planned ! (142 g). Even with the black paint inside. It just looks much better when duct is dark than just 'clear' ! I'm confindent that the final weight should be below 1000 g even with the two 50mm metal EDF that I ordered (93 g each compared to 45 -50 g for a plastic EDF) Here is a few pics of the result. Still need to do a few thing here and there. The top fuselage is made of foam sheeted with 1/16 balsa. The rest of the fuselage is from 3/32. After covering it is stiff enough for that kind of airplane. I need to build the mould for the canopy. Edited By Sylvain Le Gall on 12/03/2013 03:05:54 Edited By Sylvain Le Gall on 12/03/2013 03:06:12 Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted March 14, 2013 Author Share Posted March 14, 2013 A few pics of the work in progress. I made the wing (or so) in 2 evenings (1 for the build, 1 for the covering). I have 204 g compared to the 197 g I planned. not bad...but... This mean i will be under 1 kg at the end. (maybe 950g). On 4S the 2 EDF should provide around 2x600 g static trust with 2x26 Amp. But these are the numbers I found on the web... At the end, the flat wing looks OK, but I have to say that the ratio 'efficiency' vs (weight, lift, drag etc...) is not the best. I guess if this combo airframe/setup is nice, I'll find a way to enhance all that (fiberglass fuselage, sheeted foam wings...)...We'll see. Edited By Sylvain Le Gall on 14/03/2013 16:15:51 Edited By Sylvain Le Gall on 14/03/2013 16:44:30 Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted March 14, 2013 Author Share Posted March 14, 2013 PS: concerning the wing. During the design I was thinking about an alternative to the full balsa wing: - 1/4 (or 6mm) light balsa on the leading and trailing edges (+other few places) - 2 carbon wing spars - 6 mm depron for the rest of the wing This would have probably end with a ligther a stiffer wing...but...I wasn't able to find the precious depron here in Canada... Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted April 13, 2013 Author Share Posted April 13, 2013 It's been a couple of weeks since I spent time on this one... Here are a few pics of the plane ready to go (no trim yet...but) : I vacuum formed the canopy yesterday evening. The fit is not bad. Quote Link to comment Share on other sites More sharing options...
Mowerman Posted April 13, 2013 Share Posted April 13, 2013 Looking very good. If it flys as good as it looks you will be on a winner. Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted April 13, 2013 Share Posted April 13, 2013 Hi Sylvain , I can tell just by looking at it , it will fly Great . I`ll be waiting for the Video Great looking model , Quote Link to comment Share on other sites More sharing options...
Johnny Kirkham Posted April 13, 2013 Share Posted April 13, 2013 What a stunning looking tool that is......well done!! Cant wait for a flight video Johnny Quote Link to comment Share on other sites More sharing options...
sgwlm Posted April 14, 2013 Share Posted April 14, 2013 excellent looking plane, i think i need one of these in my hanger, any chance you will make the plan/drawing available look forward to seeing more pics and in flight shaun Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted April 14, 2013 Author Share Posted April 14, 2013 Hi Shaun, Will have to do test flight before releasing any plans. I dont' want to be responsible for sharing experience on something that flies like a bolt But for sure, if everything goes well, I will definitely publish the plans and tips for those who will be interested.This should be in the next couple of days/weeks once the the snow will melt here ! Stay tuned. Edited By Sylvain Le Gall on 14/04/2013 18:28:17 Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted May 15, 2013 Author Share Posted May 15, 2013 A few updates on this one. I've been working a bit on the trim scheme. Not something fancy but I found a few stickers on the web that fit pretty well the MiniJet. I need to paint the bottom in flashy colors to get a good vizualisation in flight. (maybe in red). Anyways, here it is : Hope I will fly her this weekend. Cheers Quote Link to comment Share on other sites More sharing options...
sgwlm Posted May 16, 2013 Share Posted May 16, 2013 this is looking fantastic, hope test flight is good, i need one in my hangar Quote Link to comment Share on other sites More sharing options...
Stephen Jones Posted May 16, 2013 Share Posted May 16, 2013 Good luck , It looks almost space shuttle like . Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted May 17, 2013 Share Posted May 17, 2013 Superb designing and building - best of luck with flight Quote Link to comment Share on other sites More sharing options...
Mowerman Posted May 17, 2013 Share Posted May 17, 2013 As you are in Canada and I think this looks a bit Avro Arrow ish. Would it look better with RCAF markings? Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted May 17, 2013 Author Share Posted May 17, 2013 @ Roy Yeah I know...shame on me. But the moment I ordered for the stickers, I was not able to find Canadian Air force ones.... Hope the mates at the field will still talk to me ! Hopefully, I will do the test flighht this week end. cheers. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted May 17, 2013 Share Posted May 17, 2013 Sylvain Are the fans in? Where is the Lipo? I have been flying my own delta today, the one aspect that constantly surprises me is how the drag increases dramatically when turning. That is the model effectively stalls, if the power is not increased, from a nice cruise, this is apparent, that it goes of in the direction it chooses, until speed builds up again. I have found that if the power is not increased when doing a bank and yank turn, it just pancakes out of the sky. The reason I mention this aspect, is i would guess, that with DF, the power needs more management than my pusher prop job. I guess IC models suffer less in that the power is always there until the last drop of fuel runs out and that battery power management is not part of the package. My own model has I think a 45 degrees sweep, it was a convienant angle on my adjustable set square. Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted May 17, 2013 Author Share Posted May 17, 2013 Hi Erfolg, The fans are in, I would say about 10 cm from the end of the exhaust. Intake and exhaust area have been calculated with standard methods to provide standard EDF efficiency. Hope it is going to be fine. Access to EDF units is easy when the wing is removed. I'll take some pics. Battery is located in the nose (4S 2750mAh). I had to add some lead in the nose to achieve the CG....Rrrr, I hate that. I guess with nylon EDF units (not alumium like mine) the balance would have been perfect...). In My proto, I have to remove the wing (2 bolts) to acces to the battery. I may modify and build a hatch on the bottom latter on. It also reminds me that I have to buid a air intake to cool the battery . Sweep is 31 degrees in mine, which I found to be a good compronise. Concerning flight: Thank you for your input. I flew a few EDFs by the past and one delta wing, but it was (and still is) a bigger one with lot more inertia, so I guess your advice may be critical. Wing loading is around 50g/dm2 which is not bad, she should not bite to hard. Thank you guys for your inputs, really apreciated. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted May 17, 2013 Share Posted May 17, 2013 I am not suggesting that deltas are tricky to fly. In some respects they are more tolerant, especially the CG. I have had my own moved over 2 inches, with little real impact. There are only two aspects, that is very high angle of attack approaches and turns. The power requirement is high, again a drag issue, at high angle of attack. Yet keep it clean, they can approach really fast, pull some up, and they just (or my own) just lands like a butterfly. If experienced on deltas, the high drag in turns will probably not surprise you. I do wonder how delta fighters get around the issue, or maybe it is just my own model. Another plus is bags of wing area for little structural weight and the low drag at speed. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted May 17, 2013 Share Posted May 17, 2013 Erfolg How does a delta jet fighter in a turn overcome the high drag? Only by using huge thrust. A Eurofighter doing a its tight air display routine has full afterburner quite a bit of the time! Edited By Simon Chaddock on 17/05/2013 23:25:52 Quote Link to comment Share on other sites More sharing options...
Sylvain Le Gall Posted May 25, 2013 Author Share Posted May 25, 2013 Guys, I brought the mini jet to the field last monday. I built a removable landing gear for the occasion. And....I was not able to fly her... because I forgot my bungee at home. I did a few test from our grass field though, to see if could get her airborn from the ground. No way ! Our grass is way too bumpy ! Anyways, I hope this week end will be the good time. Here are a few pics. Edited By Sylvain Le Gall on 25/05/2013 00:09:27 Quote Link to comment Share on other sites More sharing options...
Erfolg Posted May 25, 2013 Share Posted May 25, 2013 It looks very good. One thing is certain for that first flight, you must give yourself the best chance possible. So I understand your initial caution. Best of luck. Quote Link to comment Share on other sites More sharing options...
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