Alan Jarvis Posted March 18, 2015 Share Posted March 18, 2015 Been having a think about what I am going to do with the Vulcan. Make it into a PSS but I will already have one and I don’t fancy lugging this one up a mountain (hill) Make it back into Tony N twin pusher. Quite a bit of work cutting two wings back and making good. Two motors and two ESC’s Fit a turbine £1200 only joking Buying four 50mm fans that run on 4s. They would give 200g more each ( is that enough) but will need bigger batteries. Fans £24 each plus I will need four ESC’s another £100 =£200. Cut the tail cone back a bit and fit a decent motor with one prop. If I go for option 2 or 5 I may need retracts to avoid chopping my hand off. £76.00 Option 2 and 5 will put a lot of weight at the back and removing 4 fans from near the front will reduce weight. I could of course use the area where the fans sit for some big batteries. My Vulcan weighs 1.75 Kg 3.8 lbs The fans weight 67g each = 268g or .6 lb. Rough round figures 4 Lbs with one motor and battery. Wouldn’t need a very big motor for that. I am favouring option 5 what do you guys think. Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 18, 2015 Share Posted March 18, 2015 Alan There will be one problem with option 5, when the model rotates to take of, with the Vulcan you will experience prop strikes. Probably option 2 is the best option, although you will probably need high Kv motors to get the prop dia. down, for similar reasons. The feed back you guys have made is extremely useful for us modellers, as it has indicated that DF is probably an issue for most of us. Your weights seem quite low to me and I would have expected greater success as built. A great pity. If i build one, it will have to be pusher props it would seem. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 18, 2015 Share Posted March 18, 2015 Alan, that option 5 actually looks to be a possibility although it would destroy the scale outline. Looking at mine, a 7" prop may be OK but how about a 6" three blader on a fairly high kv motor with a small battery pack in the nose to balance and only provide some extra oomph for take off? It should be possible to mix this in or out as required but don`t ask me how as yet. Anyone else have any bright ideas on this? Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 18, 2015 Share Posted March 18, 2015 The thing which inspired me to build this was a club mate`s HK Vampire with similar sized wheels. It crawls across the grass but somehow gets airborne most times. Edited By Martin McIntosh on 18/03/2015 21:11:35 Quote Link to comment Share on other sites More sharing options...
PeterF Posted March 18, 2015 Share Posted March 18, 2015 I have not built this, but have a larger B2 stealth I am having similar issues with. I have removed the retracts and built a light weight dolly with large diameter foam wheels and that has been of some use. I have 55mm carbon Vasa fans in it running on 6S, 55,000rpm, 800g thrust at 480W, 4 of those would ROG the Vulcan if it could carry the batteries. Quote Link to comment Share on other sites More sharing options...
Bucksboy Posted March 18, 2015 Share Posted March 18, 2015 Martin, I can offer you an AstroTurf runway in Rickmansworth, Herts, close to Bucks. It's very flat and hard and most foamy models take off from it. PM me ir you're interested, you'd need BMFA insurance though Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 18, 2015 Share Posted March 18, 2015 Thanks for the offer Bucksboy, I shall be in touch soon. Martin Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted March 19, 2015 Share Posted March 19, 2015 Alan. Could you get away with uprating two of the fans, leaving two original units, you might even find that the uprated motor and rotor will fit in the original housings. I have two seven blade units and two five blade units in mine. In theory this gives me enough power fro moderate flight but has not been put to the test yet. Glenn Quote Link to comment Share on other sites More sharing options...
Alan Jarvis Posted March 19, 2015 Share Posted March 19, 2015 Glenn Let me know the results when you have flown I am not rushing this. Are you using 3s? Alan Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 19, 2015 Share Posted March 19, 2015 From watching models such as the Vulcan, and particularly a model Vulcan in one of my clubs, prop strikes are very common. The reason being, the position of the rear UC wheels, relative to the position of the motors. As the model rotates for take of, the trailing edge of the wing and with the Vulcan, the rear radome, move closer to the ground. In the case of the radome, it sticks out a lot, even a very modest increase in the angle of attack, brings this item close to the ground. A motor mounted in this position places the propeller arc, almost certainly below ground level, even with a small dia propeller. When the motors are mounted on the jet efflux positions, the issue reduces, yet remains a potential issue, even when the take of is handled carefully. Quote Link to comment Share on other sites More sharing options...
Alan Jarvis Posted March 19, 2015 Share Posted March 19, 2015 Erfolg Given I don't have retracts I don't think prop strike will be a problem. I would fit a folding prop for landing. I have a big foamie with a big folding pusher prop and even hand launch has never been a problem. I do have a bungee frame so would probably launch from that. Alan Quote Link to comment Share on other sites More sharing options...
Erfolg Posted March 19, 2015 Share Posted March 19, 2015 Alan I was only considering models with undercarriage. My own modest delta, without UC, to date has no issues with the props (its a pusher twin) when landing. In my case left freewheeling. Quote Link to comment Share on other sites More sharing options...
Andy Fox Posted March 20, 2015 Share Posted March 20, 2015 These little beauties have arrived for my build ..... Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted March 20, 2015 Share Posted March 20, 2015 Wow they look mean ! Quote Link to comment Share on other sites More sharing options...
Alan Jarvis Posted March 20, 2015 Share Posted March 20, 2015 Andy Can you tell us what they are. I have just realised you are building a scaled up model so probably much bigger than 50mm. Edited By Alan Jarvis on 20/03/2015 11:30:17 Quote Link to comment Share on other sites More sharing options...
Andy Fox Posted March 20, 2015 Share Posted March 20, 2015 They're 70mm units from extreme rc in Australia..... Will be using 6s packs Quote Link to comment Share on other sites More sharing options...
Steve Bell 3 Posted March 20, 2015 Share Posted March 20, 2015 If like me your building the pusher version beware the recommended motors have been discontinued. Darn it Quote Link to comment Share on other sites More sharing options...
Dennis Holmes Posted March 23, 2015 Share Posted March 23, 2015 Mine has not flown yet and by reading these last posts it seems like it never will, I've thought all along during the build that the fans do not have enough thrust to get it off the strip. What I can't understand is how Tony Nijhuis states what I belive is an unachievable all up weigh he stated the fans used were hobbyking units and gave it a glowing report. Has anyone had a word with Tony about what is looking more and more like a looser, I'm not a happy chapy I don't no about you guys Quote Link to comment Share on other sites More sharing options...
Alan Jarvis Posted March 23, 2015 Share Posted March 23, 2015 I have stripped the 4 fans out of my Vulcan as they are obviously not going to work. I think my best option now is to cut the tail cone down and fit a motor and folding prop. A couple of 4s batteries were the fans used to sit should balance it up. Will need to strengthen the fuse were the fans have been removed. Bungee launch. Not very happy about it. Quote Link to comment Share on other sites More sharing options...
George Worley - 4-Max Posted March 24, 2015 Share Posted March 24, 2015 Posted by Steve Bell 3 on 20/03/2015 17:15:21: If like me your building the pusher version beware the recommended motors have been discontinued. Darn it We do have alternative motors for the pusher version which are slightly less powerful but after chatting to Tony this really should not be a problem as the original motors were very powerful Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted March 24, 2015 Share Posted March 24, 2015 hello Steve-check with BRC hobbies-they will have what you are after in the power dept....at reasonable prices etc.....and good service... ken Anderson...ne....1.....good service dept. Edited By ken anderson. on 24/03/2015 10:24:30 Quote Link to comment Share on other sites More sharing options...
Steve Bell 3 Posted March 24, 2015 Share Posted March 24, 2015 Thanks for the replies guys I've got some from Puffin models virtually the same spec. Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted March 29, 2015 Share Posted March 29, 2015 Today I started to get my Vulcan ready for flight after sorting out the bungee launch pad. I had a surprise when it came to balancing the model to get the cg right. This is 200mm back from the leading edge of the wing at the air intakes if I have understood correctly. As I have not fitted retracts I modified the wing during the build to be able to mount the batteries where the rear set of retracts would have been. To my surprise this would have meant an awful lot of lead so I decided to mount the batteries in the nose, as you can see from the photo they are still forward of the position of the nose wheel. I am not aware that I have built the tail end heavy, indeed the model with batteries is just over 4.5 lbs. I also checked the power and according to my measurements came up with 480 watts so it should fly with a bit of power to spare. Quote Link to comment Share on other sites More sharing options...
Mark Kettle 1 Posted March 30, 2015 Share Posted March 30, 2015 It's looking good Glenn. Quote Link to comment Share on other sites More sharing options...
Dennis Holmes Posted March 31, 2015 Share Posted March 31, 2015 Good luck Glen, I hope some one gets a successful flight soon, I need to read some good news about the vulcan before decisions are made with mine. My all up weight with retracts is 4 lb 15oz and it's got the hobbyking 4800kv edf's Tony used with 480g thrust, so by my reckoning I've no chance Quote Link to comment Share on other sites More sharing options...
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