scott cuppello Posted February 19, 2009 Share Posted February 19, 2009 Hi James, hope you are well, we are using our Sea Harrier.....which will be fantastic if it can be done.......it flies well as I founf out last weekend, there is tons of space in it due to it's size, but it only weighs 2lbs AUW at the mo.....perfect! Quote Link to comment Share on other sites More sharing options...
James Hindle Posted February 19, 2009 Share Posted February 19, 2009 I reckon we need to poineer this Scott, how about teaming up, can you pop one in the post to me ...... Quote Link to comment Share on other sites More sharing options...
scott cuppello Posted February 19, 2009 Share Posted February 19, 2009 You never know.........! Quote Link to comment Share on other sites More sharing options...
James Hindle Posted February 19, 2009 Share Posted February 19, 2009 You're spending too much time on here Scott, that's like a David Ashby response ! Quote Link to comment Share on other sites More sharing options...
Michael Hickman Posted February 19, 2009 Share Posted February 19, 2009 Hi Scott Any chance of some more pictures (flying if poss. )? Mike Quote Link to comment Share on other sites More sharing options...
scott cuppello Posted February 19, 2009 Share Posted February 19, 2009 I'll try and bag some piccy's this weekend....James....I'll get me coat. Quote Link to comment Share on other sites More sharing options...
Pete Rieden Posted February 19, 2009 Share Posted February 19, 2009 The video is a clip from the Icarus Aerofly Pro Deluxe RC simulator. That Harrier is one of the satndard library of aircraft that comes with the sim - I have it here on mine. The scenery is one of the standard AFBD locations. "I reckon you would need a second fan rotating in the opposite direction to the first to counter act the torque from the first (just like the real deal), when it's vectored downwards. " The spools contra-rotate in the Pegasus to cancel out the gyroscopic moments rather than torque. This was done after the lessons Bill Bedford learned when flying (and crashing) the X-14. The biggest problem with doing a model harrier isn't power or thrust - to achieve safe VTOL operation requires a thrust-weight ratio of around 1.3 to 1.5:1 and this is relatively easily achieved with today's lightweight RC and power systems (even electric). The problem is control. The full size Harrier taps approximately 10% of the engine thrust into the reaction control system (the "puffer jets"), but it has a lot of inertia damping. A few sums have suggested that a typical model size - (say 36" span and weighing around 4lbs) would need to have about 1.5lbs of reaction control thrust available to give it fast enough control authority during the transition, and about 2/3rds of this just at the hover. Even if you could create that sort of thust through the small sized pipes and nozzles that would fit in the airframe (which is doubtful) the total power and weight requirements would become impractical. You'd also need a very good gyro on the rudder during transition from normal flight back to the hover - this bit bites quite badly on most full-size VSTOL aircraft. PDR Quote Link to comment Share on other sites More sharing options...
David Ashby - Moderator Posted February 20, 2009 Share Posted February 20, 2009 "that's like a David Ashby response !" Short answers but deep in wisdom, or something Quote Link to comment Share on other sites More sharing options...
Tim Mackey Posted February 20, 2009 Share Posted February 20, 2009 We need the "Quote" facility back David Quote Link to comment Share on other sites More sharing options...
scott cuppello Posted February 22, 2009 Share Posted February 22, 2009 Couldn't get a flying shot.....all on me own! Here it is on the ground, specs are Lander 4s fan, 2200mAh 4s pack, flight times are not overly long, the model comes out nose-heavy [it needed a little lead to be buried in the tail, easy enough to do obviously....it's foam!], very scale in the air, not suprising really, it's a looker, pretty scale on the ground for a foamie, a keeper for certain.......especially as it's British. Quote Link to comment Share on other sites More sharing options...
birdy Posted February 22, 2009 Share Posted February 22, 2009 Just a thought: How about having say, 3 ducted fans that you could lower to their position. You could angle them slightly away from each other, so in theory it would be abit like the effects of dehidral. You could also try, if you have a very complicated tx, to control them by varying the thrust between them. Problem is positioning withing the aircraft to make them perticually effective, and the inefficientcy of using smaller fans. Happy pondering birdy. ps, forget quoting ; we need (more like I actually) spellcheck. Quote Link to comment Share on other sites More sharing options...
Keith Simmons Posted March 20, 2009 Share Posted March 20, 2009 Doc Watson has created a F35B using a 3 fan setup and the front fan thrust was controlled by Giros.. He did hovering flights and I don't know if he managed transition from Hover to forward flight and back. I believe the rear ducts were fixed downwards and was therefore not able to swivel to horizontal mode. Quote Link to comment Share on other sites More sharing options...
kiwi g Posted December 3, 2009 Share Posted December 3, 2009 Sorry to bring this old thread up again but I was thinking , with todays battery technology and ducted fan design has anyone tried using four fans. My thoughts are , maybe we could use 4 small fans , my favourite would be het fans with 2-20 het motors. mount them on shafts to pivot. forward and backward .control the pitch and roll with 2 gyros,and use controls the same as heli. Transion would have to be controlled by gyro as thrust would need to controlled for lift . I brought a small jump jet toy and it has a gyro that controlls four small fans through thrust and I must say its quite impressive to fly although the radio gear is cheap and you need to walk behind it but it gives food for thought... Quote Link to comment Share on other sites More sharing options...
scott cuppello Posted December 3, 2009 Share Posted December 3, 2009 The problem is weight, it has been tried but we all gave up....the technology isn't there yet, it will be I'm sure, but we are going to have to wait a bit longer. Quote Link to comment Share on other sites More sharing options...
kiwi g Posted December 4, 2009 Share Posted December 4, 2009 Thanks scott They also said a boat couldnt go up rapids in a river but a kiwi buy the name of hamilton did and its great fun. so you are telling me that all resources and methods were tried. I cannont see any mention in these threads of using four rotating fans all powered separately. But if there is can you guide me in the direction of those threads so I can read and wont be wasting my time. My mate has one working , 4 fans two batteries but we cant get transition yet. it doesnt look pretty though. Quote Link to comment Share on other sites More sharing options...
scott cuppello Posted December 8, 2009 Share Posted December 8, 2009 The chap that was doing the work has designed many heli's over the years, and had a hand in the Harrier indoor RTF design that is on the market. I suspect the biggest difficulty is gyro's, and linking from hover to forward flight, another hassle by all accounts was ESC's, although things are moving quickly in this game so ESC's with a fast enough processing speed, not to mention consistent throttle matching on all fans should be easier to achieve now thatn when this thread started....I wish you and your barrel the best of luck with it....sorry I can't be of more help, I just wasn't really involved in the VTOL side of things. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted December 8, 2009 Share Posted December 8, 2009 Scott A very nice model, wish you great commercial success with it. Regarding the VTOL model. To me the basic issue is simple, does one EDF unit generate more force than the weight of all the basic components. In my opinion that is fan unit with motor, battery, and ESC. If this cannot be achieved no amount of additional fans will change things, in that it will not be able to lift itself vertically. If the answer is a +VE, then the next question by how much. As we still need to build a body. With respect to paddles and ducts, these are notorious in reducing the efficiencies, not withstanding there ability to do what you want in lifting and controlling about all the axis. Yet the first question is the biggie. Has Timbo never tested a fan, if so, just need the weight of the set up. Quote Link to comment Share on other sites More sharing options...
birdy Posted December 8, 2009 Share Posted December 8, 2009 Posted by Erfolg on 08/12/2009 13:41:35: Regarding the VTOL model. To me the basic issue is simple, does one EDF unit generate more force than the weight of all the basic components. In my opinion that is fan unit with motor, battery, and ESC. If this cannot be achieved no amount of additional fans will change things, in that it will not be able to lift itself vertically. I'me pretty sure it can... Especailly if you have a small battery and a big fan.... Quote Link to comment Share on other sites More sharing options...
Erfolg Posted December 8, 2009 Share Posted December 8, 2009 Birdy There is only one way and that is to put together the basic equipment on a Timbo type test stand if you have one, or alternatively place your fan on a digital kitchen scale so that it can draw air from underneath and exhaust up. Any Heath Robinson affair will do that is safe. Switch on and see how much heavier the scale reads. Simples, now you know if a model is even worth considering. Although a great believer in electric models, I wait with bated breath to be pleasantly proven mistaken, and that the concept flies. Erfolg Quote Link to comment Share on other sites More sharing options...
kiwi g Posted December 9, 2009 Share Posted December 9, 2009 One of the biggest problems we have had was inital stability. Now dont get me wrong guys when I say we have one flying on for fans we are talking smallish batteries four fans and minimal experimenting time. hover is no more than a couple of feet for a couple of seconds , but it shows possilities. We were struggling with gyros etc but we went and had another look at our setup . We still use gyros but we found that if we tilted the fans out and gave the front a forward tilt (a bit like chair legs ) the stability was alot better . our plans are to make one with all the fans approx 10 degrees opposed to each other and to make a simple transition we thought we will try to bring the forward fans back and add more power as we do this. Hence at the moment the fans work against one another in hover but rotating the front fans from 10 degrees positive forward to 10 degrees rear may give us the basic forward movement we are after. Like I said its early days yet but great fun trying Cheers kiwi geventor Quote Link to comment Share on other sites More sharing options...
Paddy Fidling Posted December 9, 2009 Share Posted December 9, 2009 This Guy looks like he has the right idea with an osprey. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted December 9, 2009 Share Posted December 9, 2009 Paddy I cannot say how impressive I find this model. Does any one know the details about it? It does not seem to be just two motors, acting as a semi helicopter, the lift arrangements look complex, from the freeze frame. The stability seems exceptional, do people think or know if gyros ar used in some way? As to the four fan arrangements of kwi, this seems similar to the indoor harrier, which looks like a 4 rotor helicopter. You have to squint long and hard to see a Harrier. Or have you geninely managed to get an EDF and gubbings to lift itself. I still have difficulties in seeing how a harrier can fit in 4 fans and look like a harrier. If fans can be made to lift theselves perhaps the aircraft below may fair better using the methods of that V22. It was made by Messerscmitt, Heinkel and Bolkow . There are a number of other possibles Bell X22, Dornier DO31Lockhheed XV4 Hummingbird, all assuming that the EDFs can generate a healthy surplus of thrust over weight Quote Link to comment Share on other sites More sharing options...
scott cuppello Posted December 11, 2009 Share Posted December 11, 2009 You mean details on the Harrier kit? It's Guanli, so you are going to need to have a look in Hong Kong for one, I would start by dropping Raymond a line at www.rc-castle.com, he can get them, and I'm sure would if asked. The kit isn't particularly expensive, and takes a 70mm fan, but it needs a LOT of power because of the in-efficiency of the eflux [I have a Lander unit in there with a 2W-20 HET motor, so around 700w on 4s...it flies nicely on this but it's no missile], it's biger than most expect it to be, but weighs nothing, mine is barely 2lb wet through, loads of room in it for messing with fans, etc, removable wing which is a nice feature. To make the VTOL more practical, the model is nose-heavy with a 4s pack up front, but there is tons of room in the fus to mount another pack, in fact there is a ply plate for the elevator servo, etc, BEHIND the wing, so lot's of possibilities to have a crack at it! Quote Link to comment Share on other sites More sharing options...
Tony Read 2 Posted December 15, 2009 Share Posted December 15, 2009 Here is is website http://www.rcpowers.com/ some of his videos are quite funny. I like the one about hand launching a park fly jet. Quote Link to comment Share on other sites More sharing options...
Tony Read 2 Posted December 15, 2009 Share Posted December 15, 2009 oops! Didn't notice pages 2 & 3! Quote Link to comment Share on other sites More sharing options...
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