Andy Stephenson Posted November 16, 2020 Share Posted November 16, 2020 On an Irvine.53 mine will accelerate vertically on 2/3 throttle so on an OS .55 it will be something else. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted November 16, 2020 Share Posted November 16, 2020 As a matter of interest, current F3A aircraft have between 250 - 280 watts/lb. The power is used to fly large manoeuvres at near constang speed. So 200 watts/lb is quite modest in comparison. Quote Link to comment Share on other sites More sharing options...
Mark Jones 10 Posted November 16, 2020 Share Posted November 16, 2020 Posted by Andy Stephenson on 16/11/2020 20:28:17: On an Irvine.53 mine will accelerate vertically on 2/3 throttle so on an OS .55 it will be something else. The Irvine 53 has more power and lower weight than the Os 55 ax Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted November 16, 2020 Share Posted November 16, 2020 Current F3A models have extremely draggy fuselages so I guess this is why they need so much power although I don't get the need for such thin wings. Quote Link to comment Share on other sites More sharing options...
Jonathan M Posted November 16, 2020 Author Share Posted November 16, 2020 Posted by Paul Marsh on 16/11/2020 19:39:09: Don't go on Mick Reeves website, just went on, and the virus checker blocked a Trojan. The website has been hacked. Given that it was always a complete travesty of a website, that's hardly surprising. 1 Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted November 16, 2020 Share Posted November 16, 2020 Posted by Andy Stephenson on 16/11/2020 20:54:31: Current F3A models have extremely draggy fuselages so I guess this is why they need so much power although I don't get the need for such thin wings. You actually aim to fly at less than 1/2 power Andy. Mine shows just over 1 Kw and the max on an upline is about 2.6 - 2.8 kw. Unlike the earlier 10 cc models, which were flown very fast, today you generally.see models which fly relatively slowly. The fuselages aren't particularly draggy but they have gained a lot of side area as there are a lot of manoeuvres flown in knife edge or roll/pitch where the additional lift is very welcome. About 90% are now electric powered and use specilist ESCs to provide prop braking on downlines to keep the speed low. Contra rotating props generate a lot of drag even without ESC braking. Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted November 17, 2020 Share Posted November 17, 2020 Posted by Paul Marsh on 16/11/2020 19:39:09: Don't go on Mick Reeves website, just went on, and the virus checker blocked a Trojan. The website has been hacked. I think your 'virus checker' may be paranoid. (Better get a Mac ) Quote Link to comment Share on other sites More sharing options...
Jonathan M Posted November 17, 2020 Author Share Posted November 17, 2020 So an update on recent progress. The 'improved' rear fuselage can be seen in the photos below. One major error in the design is that the upper part of the formers (the 'triangular' bits) were incompletely thought through: the angle of the slopes do not match up, especially at the tops where at the very least the capping pieces are supposed to run true! The solution to this was to trim the offending slopes back to the correct angles, then add extra strengthening balsa etc. I hope the photos make sense. Quote Link to comment Share on other sites More sharing options...
Jonathan M Posted November 17, 2020 Author Share Posted November 17, 2020 Completed, the rear fuselage now looks like this - altogether less flimsy without adding a huge amount of extra weight: Quote Link to comment Share on other sites More sharing options...
Piers Bowlan Posted November 17, 2020 Share Posted November 17, 2020 Those mods look like a great improvement in strength without adding significantly to weight. Pity the original kit isn't designed like that. Following with interest. Quote Link to comment Share on other sites More sharing options...
Jonathan M Posted November 17, 2020 Author Share Posted November 17, 2020 Back to the front end of things: As I'd decided to encase the fuel tank in foam, I ordered a slightly smaller 10oz version (the kit supplies a 12oz one), and relieved the opening in the light-ply former aft of the bulkhead so the supporting foam would more reliably insulate the tank from any vibrations. Having originally enlarged the hole in the bulkhead to fully accommodate the cap of the fuel tank as far forward as possible, now however that the tank is to be very slightly further aft due to the foam, I made a circular recess and epoxied in a thin ply blanking-piece, into which I bored three perfect-fit holes for the fuel-tubing, which also now properly clear the nose-wheel piano wire. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 17, 2020 Share Posted November 17, 2020 Piers, the original kit was a product of its day and it was a good offering for the time, with die crushing technology and cut foam wings. Now we have laser cutting & cnc mills. Although we shall see, veneered bead foam may yet return to kits if balsa stays expensive. The only issue I take with laser cut holes in balsa like that is that the crossgrain wood in between the holes might as well not be there, for all it contributes. Then, if you take the "cutting big holes in things" method to its logical conclusion, you might as well build a vintage style truss from 1/4" square stock. Or lose the truss, use liteply formers to form the uprights, and put square stock in the corners. The crossgrain sheet on the top of the lower box is rather redundant by the time the deck parts go on - better strength/weight would be gained by having that full crossgrain sheet on the underside, and deleting the "lower box top sheet". I appreciate these sorts of choices are all fair compromises to suit a laser cutting production run and a quick build. Means to an end, etc. "The fuselages aren't particularly draggy" I beg to differ. The giant F3A fuselages have lots of induced drag, by comparison to a "regular" fuselage on the same wing area. But I would also contend the drag is not particularly important in the context of slow flight speeds with a need to maintain that speed during uplines. The large drag will help with downline control and as you say lift in knife edge. Quote Link to comment Share on other sites More sharing options...
Jonathan M Posted November 17, 2020 Author Share Posted November 17, 2020 The last jobs before moving onto the wings (which I'll get round to shortly) were: I strengthened the bottom of the light-ply former where the wing's locating-peg enters by adding a doubling-piece - again very little weight gain for extra peace-of-mind! Prepared the curves in the top and bottom decking pieces, simply by painting one side with tap-water to swell the fibres then wrapping around a cardboard tube overnight. The bottom one cannot be glued in until the wing is complete and in place for final trimming and fitting, so I've left these for now. Finally preparing the solid tail parts. As described earlier, I quickly CA'd the laser-cut parts together just to obtain the outlines, then jointed up solid parts from 1/4" balsa, which are yet to be finished. (IMPORTANT NOTE: the tailplane will NOT eventually fit into the slot if it is full width - the laser-cut parts include a narrow piece to be glued to the very front of the centre-section after insertion, so allow for this if/when making a solid tailplane.) Until next time... Jon Quote Link to comment Share on other sites More sharing options...
Mark Jones 10 Posted November 17, 2020 Share Posted November 17, 2020 Following this with interest. Looking forward to getting mine Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 17, 2020 Share Posted November 17, 2020 " light-ply former where the wing's locating-peg enters" crikey, was that just a single thickness of liteply? anyway, fuselage is looking good now Jonathan Quote Link to comment Share on other sites More sharing options...
Jonathan M Posted November 17, 2020 Author Share Posted November 17, 2020 Yes Nigel, just single thickness. Like I said a while ago, there are a quite a number of 'cut corners' in this design. So, especially as someone who hadn't ever before built a RC power kit (only several very small FF scale jobs for rubber etc, and a Middle Phase), the amount of time spent on thinking, researching and deciding-how-to-do-it-properly has been somewhat excessive! Anyway, here's a picture of my method for withdrawing the fuel-tank should it ever need future maintenance (thanks for your earlier velcro suggestion!) using a cable-tie secured with armoured tape! 1 Quote Link to comment Share on other sites More sharing options...
Mark Jones 10 Posted November 23, 2020 Share Posted November 23, 2020 Having thoughts about converting the Gangster to tail dragger. Has anyone done it ? many pictures/advice would be great Mark Quote Link to comment Share on other sites More sharing options...
Stuart Z Posted November 23, 2020 Share Posted November 23, 2020 The 75 was a tail dragger so pictures or plans my be out there. There’s also a build on here Review S Edited By Stuart Z on 23/11/2020 09:49:45 Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 23, 2020 Share Posted November 23, 2020 I would think it should be straightforward to convert to taildragger and would certainly make the engine mount area easier to deal with. Existing wing mounted legs and ply/HW mount blocks would need moving forward so the wheels (not axle) are level with the leading edge. Wing ribs would need a bit of surgery to accomodate that. I guess there are some ply doublers to support the blocks, so they could maybe be reused, but if not then new doublers are easy enough to manufacture. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted November 23, 2020 Share Posted November 23, 2020 Ah, Nigel and Stuart beat me to it. If you follow the link in Nigel's post and scroll down you will come to a view of one wing at the root showing the position of the cut out for the U/C bearer. It's quite a long way forward. Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted November 23, 2020 Share Posted November 23, 2020 On the link above, go to page 3 and the 4th post down shows a photo of the wing with the u/c fitted. OTOH here it is! Quote Link to comment Share on other sites More sharing options...
Mark Jones 10 Posted November 23, 2020 Share Posted November 23, 2020 Thanks guys for the info 👍🏽😄 Quote Link to comment Share on other sites More sharing options...
Mark Jones 10 Posted December 19, 2020 Share Posted December 19, 2020 Build is going quite well. Not happy about wing ailerons and may fit them in a more traditional way upright. has anyone got pictures of how theirs finished up ? Quote Link to comment Share on other sites More sharing options...
gangster Posted December 19, 2020 Share Posted December 19, 2020 This thread seems to encompass two different models the gangster lite and the traditional one. If the aileron question refers to the traditional one yes there is an issue there. There can be an issue with flutter which is easily solved by stopping the aileron a couple of inches before the wing tip and fixing the rest of the trailing edge Quote Link to comment Share on other sites More sharing options...
Mark Jones 10 Posted December 19, 2020 Share Posted December 19, 2020 Posted by Mark Jones 10 on 19/12/2020 16:56:30: Build is going quite well. Not happy about wing ailerons and may fit them in a more traditional way upright. has anyone got pictures of how theirs finished up ? Sorry I meant the aileron servos and their fitting Quote Link to comment Share on other sites More sharing options...
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