Steve Kenney Posted October 5, 2013 Share Posted October 5, 2013 Like the look of that, Caveman. I have the same sort of keycam, so will try that on mine. Thanks, Steve Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted October 15, 2013 Share Posted October 15, 2013 How did you guys get on with the front cowl ? I've now purchased the Hobby King motor that John recommended As the giant shark motor would not fit the folding spinner. I made the first cowl and only had 1mm of balsa around the sides which just went like paper as the motor is almost as wide as the fuselage . I have had to add 1/16 of balsa to each side to try and give me enough to make the cowl, but I'm trying my best not to add the dreaded weight to the front. I have now made a very snug fitting cowl around the motor , but just need to shape it without breaking through to the motor again. Quote Link to comment Share on other sites More sharing options...
John Roberts 9 Posted October 16, 2013 Share Posted October 16, 2013 Hi Roy, The cowl was a bit fiddly to make. The plan suggests using a shaped motor surround carved and sanded from a soft balsa block. I decided against this method. Instead I extended the length of the fuselage sides so that they formed "cheeks" either side of the motor. The gap between the inside faces of the cheeks is 30mm which leaves 1mm clearance on each side of the motor which is only 28mm in diameter. I then used soft balsa blocks above & below the motor (glued between the extended fuselage sides) with 4 small pieces of triangular balsa glued in the corners. Viewed head on this produced an octagonal shaped cavity with a diameter of approximately 30mm and the motor sits comfortably inside. Being fussy I also used a bit of broom handle wrapped with sandpaper to make the cavity more circular and also to give just a tad more clearance around the motor. The exterior shape of motor surround was then achieved with a small plane and sandpaper. At a guess the minimum wall thickness in a couple of places is a bit less than 1/8th but generally it is quite a bit more and once covered it seems to be very sturdy. Incidentally I didn't use the 'X' shaped aluminium motor mount (it was too big to fit easily) preferring instead to locate the motor directly onto F1 with 4 short cap head bolts passing through the rear of F1 & which can be easily accessed from inside fuselage cavity. All of this is far more difficult to describe than it was to execute in practice. I will try and take a couple of photos and post them here later which might help with clarity. Cheers, John Quote Link to comment Share on other sites More sharing options...
John Roberts 9 Posted October 16, 2013 Share Posted October 16, 2013 Hello A couple of detailed close-ups that might assist. Cheers, John Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted October 16, 2013 Share Posted October 16, 2013 Thanks for your help John, that makes great sense, I wish I had done the same. I used the X motor mount which as you know was very tight. I should have thought about it and done the same as you. I will see how my cowl turns out if not I will rebuild the fuselage again making it with longer sides and get rid of that mount. Thanks for the photos. Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted October 16, 2013 Share Posted October 16, 2013 Looks just like mine. I didn't use the alloy star mount either. I have more pictures of my build if anyone wants them, I'll upload some more. CR Quote Link to comment Share on other sites More sharing options...
John Roberts 9 Posted October 16, 2013 Share Posted October 16, 2013 Roy, If your cowl doesn't turn out right do you really need to go to the lengths of rebuilding the fuselage? I would be inclined to remove the cowl, cutting it off flush with the front face of F1. You can then dispense with the X mount and re-drill F1 allowing you to attach the motor directly to it as Chris & I have done. Then its just a matter of constructing a balsa box around the motor using scraps of balsa and some triangular fillet pieces. Sand to shape and the job is done . Of course without seeing a picture of your build/installation I can't be 100% sure that my suggestion will work but I would give it some serious thought before ripping the fuselage apart and starting again. Good luck! Cheers, John Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted October 16, 2013 Share Posted October 16, 2013 Thanks for the pictures, that cowl looks like a work of art, keep the pictures coming. John Thanks once again, the main reason I said I would re do the fuselage was because I have added more balsa to the sides and I didn't want to have CG problems. I will keep going with the build and see how it turns out first before making any drastic changes. Thanks once again Roy Quote Link to comment Share on other sites More sharing options...
thelonius9a Posted October 16, 2013 Share Posted October 16, 2013 Hi folks . So here's another one almost ready to maiden.......... There are slight differences to the plan. As you can see I have taken the top nose line straight without the break for the cockpit. Also I have taken up Chris's offer of building the wing with a flat bottom (so to speak). The boom is 6x4mm tube and the rear of fuselage to front of tail is 15.5 inches. All up weight is exactly 16 ozs and it balances with no extra ballast. The fuselage sides are 2.5mm Obechi and somehow I ended up with a sort of air-scoop effect at the front..... I used the ally cross motor mount but had to file flats on the sides to get it in. This has to be done carefully so that material is removed equally to maintain the motor centre line. Tidying up to be done with Solarlac etc and then there's no further excuse. Wish me luck. Peter. Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted October 16, 2013 Share Posted October 16, 2013 It looks very nice Peter, and it's great to see yet another Whiz Kit about to get airborne. This model has been by far the most popular of my designs so far. CR Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted October 16, 2013 Share Posted October 16, 2013 Well I've had a very productive evening the cowl that I made has come out really well and I can now carry on with the build. I have made the rear block for the carbon rod and it is now glued in place waiting to dry . I inserted the rod and leveled it all before clamping in place, I'll soon be at the C G stage . I will try and get some photos uploaded soon, I just need to remember how to do it as I am now posting via my iPad. Thank you once again for all your help with this enjoyable build. Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted October 17, 2013 Share Posted October 17, 2013 Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted October 17, 2013 Share Posted October 17, 2013 Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted October 17, 2013 Share Posted October 17, 2013 Quote Link to comment Share on other sites More sharing options...
John Roberts 9 Posted October 17, 2013 Share Posted October 17, 2013 That cowl looks spot on Roy . I am pleased that you got it sorted out. Cheers, John Quote Link to comment Share on other sites More sharing options...
Steve Kenney Posted October 24, 2013 Share Posted October 24, 2013 Hi fellas, had the maiden flight today. Flew away well from hand launch on half throttle. A little nose up, but some down trim sorted that. I turned across wind and seemed to lose control and splat! (wind speed about 8mph) Some damage but repairable and all electrics working ok. I did wonder tho about the tail feathers at the end of that carbon tube - the tail has a lot of flexibility (ie flexing) and wondered if my tube is too flexible, allowing the tail to flex too much in flight. My carbon tube is 6mm dia, (5mm internal) and is 15.5 inch long from end of fuz to tail, as that's what I already had in my stock, should I be using a thicker one? What have you other fellas used? Quote Link to comment Share on other sites More sharing options...
John Roberts 9 Posted October 25, 2013 Share Posted October 25, 2013 Hi Steve, Very sorry to hear your bad news. I guess that it could be down to the carbon tube flexing wildly. My Whiz Kid ended up with a boom which is just over 20 inches long. The carbon tube I used was also 6mm (external) but the wall thickness was 1mm giving an internal diameter of 4mm whereas your wall thickness is only 0.5mm. Oddly enough I flew mine yesterday (very sprightly it was too with its larger prop - see my earlier posts for more details) and, whilst I have always had slight concerns about the length and flexibility of the extra-long carbon boom, it flys nicely. Do you intend to rebuild yours? Earlier posts in this thread suggest that a 7mm x 5mm boom might be a better choice although this was recommended to assist with CG issues rather than flexing. Good luck. Cheers John Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted October 25, 2013 Share Posted October 25, 2013 Hi Steve. I have never had any trouble with boom flexing as the carbon fibre tube is incredibly stiff for its weight. Even if yours does flex a bit, there is no obvious reason why this should occur in the air. My much larger Pogostick design had a tube that was flexible in torsion, but not laterally or vertically. The tube used to twist during rolls so that the tailplane and fin lagged behind the wings. This looked very odd, but had no effect on the stability of the model. Maybe you were just caught out by a crosswind gust. CR Quote Link to comment Share on other sites More sharing options...
Steve Kenney Posted October 25, 2013 Share Posted October 25, 2013 Thanks for responses guys. I will repair/rebuild with a slightly thicker tube and see how that goes. Oh the pleasures of aero modelling!. I remember when I first built my Mercury Matador, freeflight model,many,many years ago. I launched it and it flew away, never to be seen again!....... Edited By Steve Kenney on 25/10/2013 22:10:11 Edited By Steve Kenney on 25/10/2013 22:11:04 Edited By Steve Kenney on 25/10/2013 22:11:35 Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted November 2, 2013 Share Posted November 2, 2013 Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted November 2, 2013 Share Posted November 2, 2013 Here she is ready to maiden the CG worked out fine the boom is longer in the photo as it wasn't glued in place. the boom is 18" long . Thank you to everyone and to Chris for an enjoyable 1st free plan build. Quote Link to comment Share on other sites More sharing options...
John Roberts 9 Posted November 5, 2013 Share Posted November 5, 2013 Hi Roy, That looks great. I imagine that you are very satisfied with the end result, especially after the little mid-build "wobble" about the cowl. At 18 inches the boom is still a little shorter than mine (which flies very well) so I am certain that it will be fine on yours. Good luck with the maiden, let us know how it goes. Cheers, John Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted November 5, 2013 Share Posted November 5, 2013 Thanks for all your help John , yes I had a mid build wobble but with your help And advice I was back on track. I never had any fowling issues with the servos and torque rods etc which was a pleasant surprise . Thanks for your comments I'll keep you posted ................if the weather ever improves! Quote Link to comment Share on other sites More sharing options...
Chris Reid Posted November 5, 2013 Share Posted November 5, 2013 You've made another nice looking Whiz Kid Roy. Good luck with the flying - take it easy with the throttle at first. Chris Quote Link to comment Share on other sites More sharing options...
Roy Mundy Posted November 5, 2013 Share Posted November 5, 2013 Thanks for a great design Chris, it's nice to see that all your hard work wasn't in vain . Hopefully there will be more whizz kids built. It was an an enjoyable build. Keep up the good work. Quote Link to comment Share on other sites More sharing options...
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