Martin McIntosh Posted November 17, 2014 Share Posted November 17, 2014 Hi Martin R., The test was carried out on the model as shown in the pic. I stated above that I have not (as yet) fitted the intake ducts because the area without them is equivalent to 2x fan area, giving an efflux of 85% of this which should be ideal. Maybe they give a lot more thrust when fitted. Will have to try these as it is clearly unsatisfactory at the moment. It is the weight which bothers me more since there are a lot of bits to fit as yet. Martin Mc. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 17, 2014 Share Posted November 17, 2014 Hi Tony B., The ply is only 1/64 and probably comes to less than 1/2oz in total. The only addition of this is on the T.E. This has been way offset by substituting balsa elsewhere, some of it thinner than shown on the plan. Even the webbing is only 1/32 balsa. All of the weight must be in the fans/batteries/retracts but it still does not explain how that at this stage it can be so much heavier than the quoted AUW. and I usually achieve lighter than the planned figures. I cannot see how it could be built any lighter. Martin Mc. Edited By Martin McIntosh on 17/11/2014 21:18:53 Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 18, 2014 Share Posted November 18, 2014 Banging on. This is my idea for battery hatches. The wing skin cut out was utilised and it is retained by a 1/64 ply tongue and magnets. This has been built as light as possible and will require a pull tab to release the magnets. No replies regarding the weight as yet. Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted November 19, 2014 Share Posted November 19, 2014 Hi Martin. I guess you have not had much of a response to the weight issue as you are in front of most of us. My build is supposed to be my winter project so I am more than happy to watch you and others build so that I can pick up any improvements along the way. Today I received my 25A quad controller and it fits like a glove so now I can get on and wire up all the fans and test out the electrics. I have been looking at Lipos to see which offer the best capacity for the lightest weight and so far the Zippy compact from HK come out well with a 3300 pack weighing only 277grms. In one of your earlier posts you mentioned that you had reduced the clearance on the fan blades, I could not find the article that you mentioned, but have experimented using the Perspex box that the fans come in. One layer reduces the clearance quite nicely but I am a bit dubious as to whether to do it as I most certainly do not want the packing coming out. Incidentally check that the screws holding the spinner onto the fan blade is tight as some of mine were loose. Glenn Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 20, 2014 Share Posted November 20, 2014 I decided to have another go at the intake ducts, this time starting with a larger balsa rectangle, the sides being cut to the finished length only after a trial fit. I cut this roughly across at an angle and inserted each oversized piece. Much easier now but still very tricky to get a cut anywhere near to the spars. Pics show them with initial trimming done and the L.E. sheeting in place ready to finish. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 20, 2014 Share Posted November 20, 2014 Glenn, I already had TGY 2650 packs at 255gm and have bought Zippy compact 2700`s at 202gm. They are slimmer but watch that your 3300`s are not too long since I have had to cut into the webbing to even fit these. Quote Link to comment Share on other sites More sharing options...
Martin Rowe 1 Posted November 23, 2014 Share Posted November 23, 2014 That looks good! Thinking of covering some parts before I slot them together. What coverings are good? i was also,wondering what hinges people are using? I don't seem to be able to find anything? Thanks Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 23, 2014 Share Posted November 23, 2014 I already answered on P13. Remember that there is a fair bit of filler required and pre-covering, except the fin perhaps, may not be a good idea. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 26, 2014 Share Posted November 26, 2014 The fin and rudder have now been prepared ready to cover and fit at a later stage. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 26, 2014 Share Posted November 26, 2014 The ABS under fairing was found to be a little on the narrow side. Also the instructions say to leave a 3mm overhang at the front and sides (?) but in order to keep it level with the sheeting I cut it to about 1mm. The gap at the sides was filled with balsa and some small 1/32 ply plates fitted here and there for the screws. The pics as usual did not turn out in order. Quote Link to comment Share on other sites More sharing options...
Martin Rowe 1 Posted November 26, 2014 Share Posted November 26, 2014 Looking good. I am thinking About getting the intake 3d printed Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted November 28, 2014 Share Posted November 28, 2014 I spent a bit of time today checking the electronics with some interesting but confusing results. Using a Watt meter I got a reading of 330W and up 37A at peak load. By hanging the model upside down onto a set of scales which I then zeroed I got an increase in weight of 280 grms also at full load. This does not sound a lot? I also inserted the plastic strips I made to reduce the clearance on the blades and this reduced the increase to 220 grms and reduced the load. The battery I used is an old one but fully charged, at full power there certainly feels like a lot of go so I am still hoping it will be alright. I am now going to start on the inlet ducts and I think I will fit these before sheeting the center section so not according to the instruction. Quote Link to comment Share on other sites More sharing options...
Bernie Posted November 28, 2014 Share Posted November 28, 2014 very exciting ,might have a go at the larger one . Quote Link to comment Share on other sites More sharing options...
Alan Jarvis Posted November 30, 2014 Share Posted November 30, 2014 Been away for a few weeks but here is the latest. No tail, batteries, retracts, covering or paint Weighs 55 ozs or 3.4 lbs Radio going in front retract well. Doors to make for this and battery compartments Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 30, 2014 Share Posted November 30, 2014 That weight is reassuring for me Alan. Just silver solarfilmed the wing and all the bits and pieces. Will now add the nose and tail cones plus the fin and strake. My Rx. is also going in the nose retract well and am hoping to be able to use one rudder servo fitted in here to operate the nose wheel and rudder via crossed pull-pull wires. I think that the rest will be done with doped tissue. I hope to do another static pull test soon. Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted November 30, 2014 Share Posted November 30, 2014 I am please that Alan has been able to keep the weight down, I was beginning to think I might be building something that would not fly. Today I took one of the fan motors out to test on the bench, I could still only get 10A load. I may try a six bladed unit or even 4 cell lipo to see if that gives me a bit more to play with. Alan looking at your photo have you moved the battery compartment into the space for the retracts? I am thinking this might be an option for me as without retracts I am wondering where the Cof G will be and may need some movement of the Lipo to avoid having to add weight.. Quote Link to comment Share on other sites More sharing options...
Alan Jarvis Posted November 30, 2014 Share Posted November 30, 2014 Glenn No I haven't moved the batteries to the retract bay but wish I had now.It would bring the weight inboard a little and perhaps put less stress on the wing joint. I suppose I could move them but not sure I want to bother now. Good thinking on the C of G. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted November 30, 2014 Share Posted November 30, 2014 Looking a bit more like it now. The weight as depicted with motors, esc`s and battery wiring is 3lb 1oz (1400gm). Quote Link to comment Share on other sites More sharing options...
David Yarrow Posted November 30, 2014 Share Posted November 30, 2014 Hi Guys, My dad is starting to build the Vulcan and has asked me to look into which electronics to buy (he already built the Lysander, lovely model). I have looked over and over this thread but am still confused over the EDF units. I'm torn between these two: On paper these look good but I'm concerned they are under-powered: http://www.hobbyking.co.uk/hobbyking/store/__57223__HobbyKing_8482_50mm_Alloy_EDF_4800kv_3s_Version_UK_Warehouse_.html The power on these looks good but I'm concerned over the extra weight of these + bigger ESC's: http://www.hobbyking.com/hobbyking/store/__57258__Dr_Mad_Thrust_50mm_10_Blade_Alloy_EDF_4000kv_UK_Warehouse_.html Can anyone advise? Cheers Dave Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted December 1, 2014 Share Posted December 1, 2014 Hi David. I will give you my thoughts although they may not help. I am disappointed in the performance of the 5 bladed fan unit. It is rated at 18A but I have only been able to get 10A. I have tried all four units and different ESCs so it is down to the motor units. As I posted earlier I will have look at a seven bladed fan with the same motor and may even try 4s to see what power I get. Having said that these are the units that Tony suggested and the weight that others are achieving means that even at the lower power they should fly OK. No doubt that the 10 blade unit will give more power, the weight difference is not much at 14grms each. If they do run at the rated power of 27A then unless you have much larger batteries the duration will be poor. Quote Link to comment Share on other sites More sharing options...
David Yarrow Posted December 1, 2014 Share Posted December 1, 2014 Hi Glenn, Thankyou for the reply. I think I will go for the lower powered units and make sure he builds light. I would rather he not end up with a heavy plane with poor duration. It will be interesting to hear your results with the 7 bladed fan. Quote Link to comment Share on other sites More sharing options...
David Yarrow Posted December 1, 2014 Share Posted December 1, 2014 Hi Glenn, Thankyou for the reply. I think I will go for the lower powered units and make sure he builds light. I would rather he not end up with a heavy plane with poor duration. It will be interesting to hear your results with the 7 bladed fan. oops double post, pesky small keyboard on the phone Edited By David Yarrow on 01/12/2014 18:32:51 Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted December 1, 2014 Share Posted December 1, 2014 A free day and a marathon session which has seen the fin glued on, the strake fitted and the remaining parts covered with doped tissue. Glad to say that this little lot has only added 40gm so far. Interesting that those fans only draw 10A whereas mine take 13.5. I am using strong batteries although the readings were taken after some initial discharging. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted December 3, 2014 Share Posted December 3, 2014 Have now got the battery fixings in. The problem was how to prise the batteries from the Velcro so I wound some nylon thread round the rear end of them and can push a cable tie etc. underneath in order to pull them out. More thrust tests. With everything except the efflux rings fitted and on the packs I intend to fly with I am now getting a more encouraging 2.4lbs static. The inners by themselves gave a little more than the outers but I have a slightly squashed outer tube which needs fixing. Problem. Yet another motor wire has gone intermittent but I think that it is in a location such that I can repair. Will now fit the rings and see if they make any difference. Quote Link to comment Share on other sites More sharing options...
Glenn Philbrick Posted December 3, 2014 Share Posted December 3, 2014 I had another days experimenting. The seven blade fans turned up so I had a play with them. Using the same set up as before but substituting the seven blade for five I can now pull 16 A and 150 watts. So this is plenty of power. The downside was that the motor appeared to get hotter quicker that with the five blades. The seven blade fan can be made to fit the HK units quite easily. SO now I have the confidence to know that one way or another I will have enough motive force to fly the Vulcan. Martin its good that you more thrust also, but what do you mean by efflux rings? are these the parts you made to reduce the clearance between the blades and casing. Quote Link to comment Share on other sites More sharing options...
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