Simon Chaddock Posted March 17, 2013 Author Share Posted March 17, 2013 2 x 4s 5000mAh - wow! My V-1 is in a completely different league! The battery box in the nose. The elevator servo underneath with the radio in its own box.and the ESC on the other side. The ESC has an external finned heat sink. At this point the nose 'cut out' is glued back leaving a small hatch just big enough to slide the 1800hAh 3s battery in. Finished off with a hatch that also locates the battery. It weighs 20oz (567g) ready to go. The CofG is at 27% chord. A bit over my target of 17oz but most of that is due to the bigger heavier high C battery. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 18, 2013 Author Share Posted March 18, 2013 To my amazement it actually flies quite well. An edited video (you could not see it some of the time) of its second flight which includes a most un V-1 like loop and roll! A bit of an optical illusion but it certainly looked like it was in the trees when I cut the power to land but it glides well too and maintains aileron control at remarkably low speed. The only problem is the ESC over heats after about a minute at full power and reduces the power. Flying all the time at reduced power prevents over heating and extends its duration to over 10 minutes! I can arrange better cooling but I suspect fundamentally I am working the PLUSH 30A ESC a bit too hard. Now painted as a 1948 USAF JB2 Loon. 'Stars & Bars' still to be added to the wings and fuselage. Being basically white overall saves the weight of the paint! A 'still' from an otherwise poor video shot in the sun this morning. Quote Link to comment Share on other sites More sharing options...
Olly P Posted March 18, 2013 Share Posted March 18, 2013 Fantastic! Quote Link to comment Share on other sites More sharing options...
Stephen Stokes Posted March 18, 2013 Share Posted March 18, 2013 She looks so cool and floats ..... looks like power is more than adequate...... nice Quote Link to comment Share on other sites More sharing options...
Wingman Posted March 18, 2013 Share Posted March 18, 2013 Phenomenal, Si! You're certainly a master with the old depron Quote Link to comment Share on other sites More sharing options...
Martian Posted March 18, 2013 Share Posted March 18, 2013 superb model and planned and built so fast Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted March 18, 2013 Share Posted March 18, 2013 Simon, congratulations, that's quite an achievement. Quote Link to comment Share on other sites More sharing options...
Kelly Posted March 19, 2013 Share Posted March 19, 2013 You could mod it Quote Link to comment Share on other sites More sharing options...
Martian Posted March 19, 2013 Share Posted March 19, 2013 quite something to have your head that near the intake, mind you wasn't the piloted version just to iron out the instability of the prototype ? Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 19, 2013 Share Posted March 19, 2013 I am really impressed with both types of model. I particularly liked the sound track on Vid 1! Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 20, 2013 Author Share Posted March 20, 2013 Martian That was the story in the film "Operation Crossbow" however all the manned flights were air launched not catapulted. Hanna Reitsch did fly one but only to determine why previous attempted manned landings had crashed and killed the pilots so she undertook some high altitude stall tests to determine a safe approach speed. It was much higher than even the fastest fighter pilots were used to but she did perform several safe belly landings. The piloted version was intended as a guided bomb and a squadron was set up to fly them but it was obvious to the high command that it would to all intends and purposes be suicidal. It was deemed that such missions "were not part of the German warrior tradition" and it was cancelled. Edited By Simon Chaddock on 20/03/2013 14:44:34 Quote Link to comment Share on other sites More sharing options...
Martian Posted March 20, 2013 Share Posted March 20, 2013 Simon thank you very much for that information it is very much appreciated, I remebered some of it from my long long past Martian Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 21, 2013 Author Share Posted March 21, 2013 The next flight did not go so well. Due to the large diameter it is very hard to grip the fuselage firm enough to give any sort of forward speed (it does not need much!) without risking crushing the fuselage. In the first launch it more or less slipped from my fingures and just powered into the ground. The expletives have been deleted! The nose was badly cruushed but it still flew well enough even if it did drop little bits of Depron during the flight. I was surprised to hear the EDF start windmilling in a fast glide but I suppose it shows the inlet must be reasonably efficient. As so much of the nose had to be rebuilt I took the opportunity to relocate the ESC to improve its cooling. The ESC was mounted flush with the fuselage surface with its shrink wrap was cut away to reveal the heat sink. The same was done on the other side of the ESC with a duct fed from the nose. The duct opens into the fuselage and the air exits through a launching finger hole in the underside of the fuselage. The black areas on either side of the fuselage are fine sandpaper finger grips. Hopefully these modification will improve the launch success rate! Quote Link to comment Share on other sites More sharing options...
Martian Posted March 21, 2013 Share Posted March 21, 2013 Simon did the ESC get very hot then to need to be exposed to the elements ah wait a minute you mentioned that in your first flight I think ..looks like a fun model to fly Quote Link to comment Share on other sites More sharing options...
Stephen Stokes Posted March 21, 2013 Share Posted March 21, 2013 I had the same problem with ESC cooling so I installed a 50mm PC fan from Maplins on top of the ESC just to keep the air moving around. The nice thing with these fans, they are rated at 12v perfect for a 3s set up. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 21, 2013 Share Posted March 21, 2013 Yet again impressive Simon. Well done. Have the basic dimensions of the two different models been posted? I would be interested in reading/seeing them! Quote Link to comment Share on other sites More sharing options...
Tangental Posted March 21, 2013 Share Posted March 21, 2013 Two thumbs Simon!(V2 next?) Impressive or what! I'm new to this electrickery game(still got oil & grease under my fingernails) but on the overheating esc issue, is it overheating because it's being 'overworked' or 'underworked'? I ask this because I keep reading here, that at full 'chat' the esc switching is eased and doesn't have to work as hard at switching as at 'half chat' and therefore doesn't get as hot? Tangey Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted March 21, 2013 Author Share Posted March 21, 2013 Tangental In this case I have committed a cardinal sin and not checked the actual current draw! The duration of the battery suggests it must be drawing a good 30A at full power which probably explains why the 30A ESC is getting so hot! My own experience suggests that although the switching losses do go up at part throttle the reduction in the ohmic losses more than compensate for it. Indeed the ESC I am using actually reduces the power if it gets too hot. Clearly there would be little point in doing this if the overall energy losses actually went up at reduced power. I really should have used at least a 40A ESC. Erfolg My V-1 has a span of exactly 40" and is 59.5" from the nose to the end of the duct. With a 1800mAh 3s it weighs 20.6oz giving a wing loading of 9.5oz/sqft. It has a 55mm AEORC EDF with a 5250Kv motor and the older style 6 blade fan. The duct is a constant 55mm internal diameter. It uses an Orange 6ch Rx and a Turnigy Plush 30A ESC. Ailerons servos are 3.7g, the elevator 5g. Wing has a 14% (tail 10.5%) symmetrical section. Both are set at 0 degrees to the fuselage axis. I hope this helps. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted April 1, 2013 Author Share Posted April 1, 2013 The revised ESC cooling certainly seems to work - although the ambient temperature was ***** cold. The launch worked well enough but there was quite a bit of wind. An edited video including just the bits where its was easy to see. The total flight was just about 8 minutes. I am still amazed at how well it glides. The wind shear close to the ground resulted in a rather untidy but safe touch down, Quote Link to comment Share on other sites More sharing options...
Bill_B Posted April 8, 2013 Share Posted April 8, 2013 A great project well executed , but I do think the poor old fan needs balancing, it's sounds decidedly rough at some throttle settings. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted April 8, 2013 Share Posted April 8, 2013 Well done Simon - next step is for a clubmate to build a Tempest and have a go at wing tipping! Have you thought about adding a cockpit and a scale Hanna Reitsch? That way you can legitimately land at the end of a flight instead of cutting the motor and diving into the ground! I must say I had difficulty, as an ex-glider pilot, drawing my gaze away from those cloud streets - what a superb looking soaring day! Quote Link to comment Share on other sites More sharing options...
Tony Read 2 Posted April 8, 2013 Share Posted April 8, 2013 Hey, Simon, Cracking job and looks great in the air. If I get the Dynam Tempest can I have a go at tipping you over? Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted April 8, 2013 Author Share Posted April 8, 2013 Martin V-1s were known to 'land' more or less conventionally indeed it was 'rescued' bits from the early tests crashes that gave the US the info required to build the virtually identical JB2 which first flew just 5 months after the first operational V-1 landed in Britain! Tony The air was very cold and the sun weak so if those cloud streets had much thermal activity it certainly wasn't noticeable from the ground! And you would have to build a very slow flying Tempest in order to keep station and it wouldn't really matter if you did tip it as with ailerons my V-1/JB2 can fly inverted! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted April 8, 2013 Share Posted April 8, 2013 There must have been something rather vigorous going on up there to form them! It's to do with instability - given the right combination of heating and lapse rates. I once thermalled for quite some time in falling snow from an overcast sky in early spring near the Black Mountains while on a wave hunting week - quite a surreal experience as while I was constantly turning the snow was always coming at me from straight ahead, On Saturday we had excellent soaring conditions in less than 10 degree temperatures - several of us had gliders with us and all found plentiful lift. Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted April 10, 2013 Author Share Posted April 10, 2013 Bill-B Yes the fan does go through some periodic vibration but it is a very cheap fan. The actual vibration is not really noticeable when held in the hand. I have found these hollow stressed Depron structures not only amplify any noise but they also tend to resonate at various frequencies. Not an EDF but this Depron plane resonates beautifully at a critical motor speed. Quote Link to comment Share on other sites More sharing options...
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