Ian Bagshaw Posted November 26, 2017 Share Posted November 26, 2017 I have just acquired a 60 size Joker in need of renovation. Does anybody have a PDF plan of this plane? or could advise as to the CofG right thrust & down thrust? Many thanks Ian Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted November 26, 2017 Share Posted November 26, 2017 To help the guys to help you Ian, this is the spec And there is a free Joker 25 Plan on outerzone, which shows the C of G, and would be the same position as the larger Construction Wolfgang and Günther Matt Type F3A-Model This airplane was especially constructed for the new turnaround pattern. Wing span 178cm Fuselage 152cm Weight 3.9kg Engine Webra 61 Racing LS Radio Control Futaba Robbe CM Rex Edited By Denis Watkins on 26/11/2017 09:47:31 Edited By Denis Watkins on 26/11/2017 09:50:27 Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted November 26, 2017 Share Posted November 26, 2017 When I get a chance I'll see if I've still got the instructions from the Marvic Models Joker I had some years ago, it didn't come with a plan as it was a pre-built fuselage and foam wings. From memory I think it was just one degree of each. Quote Link to comment Share on other sites More sharing options...
Ian Bagshaw Posted November 26, 2017 Author Share Posted November 26, 2017 Many thanks Quote Link to comment Share on other sites More sharing options...
David Foley Posted November 26, 2017 Share Posted November 26, 2017 Go to one of the on line C of G calculators and a good place to start is 25% MAC. This is as far foward as you should go. Move aft as needed. I usually work between 25-35% Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted November 26, 2017 Share Posted November 26, 2017 Or, look at the plan above, and see the C of G in the centre of the wing. Quote Link to comment Share on other sites More sharing options...
David Foley Posted November 26, 2017 Share Posted November 26, 2017 It may no workout on the 60 size in the same place. Quote Link to comment Share on other sites More sharing options...
Stuart Z Posted November 27, 2017 Share Posted November 27, 2017 Hi Ian, You mentioned that you were looking for the down and side thrust also. I don’t know which Joker you have, however I had the (I think) Marvic one years ago and I believe the side and down thrust was built in at manufacturing stage. I have the DSM Joker 40 (still after all these years) waiting for build time. The kit is stashed deep in the loft but I have a copy of the instructions to hand and they do not detail an actual side or down thrust but say,”Final down-thrust and Right-thrust angles can only be found after test flying”. So again I suspect there is a “built in to fuselage” value to be added to depending on the powers of the engine. I know in the build instructions, in this case, it tells you to displace the engine mount 3/16ths to the left (looking from the rear) to allow for right thrust. HTH S Quote Link to comment Share on other sites More sharing options...
Ian Bagshaw Posted November 27, 2017 Author Share Posted November 27, 2017 Thanks for all the advice Ian Quote Link to comment Share on other sites More sharing options...
Ian Bagshaw Posted November 27, 2017 Author Share Posted November 27, 2017 I found an old post giving the CofG as 161mm from the leading edge which looks about right as a starting point. I've just set the whole fuselage level on the bench and with an incidence meter on the horizontal stabiliser levelled to zero the Firewall is pointing upwards....which I cant believe is correct. It's not going well...... Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted November 28, 2017 Share Posted November 28, 2017 Found the Marvic instructions and that too recommends 161mm back for the CofG at the wing root and an engine mount offset of 3/16". I don't remember how long the cowl is on this, but for a 4" length that would be 3 degrees or for a 6" cowl 2 degrees. Specs are wingspan 66", area 850 sq in, wing incidence + 1/3 degree, weight 8lb. Quote Link to comment Share on other sites More sharing options...
Ian Bagshaw Posted November 28, 2017 Author Share Posted November 28, 2017 That's Brilliant Bob many thanks It doesn't happen to mention where the thrust line is on the Firewall does it? the one I have has no markings. or engine mount as yet. Thanks once again Ian Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted November 28, 2017 Share Posted November 28, 2017 Sorry Ian, it doesn't. I've just looked again and it does state right on page 1 "Downthrust and rightthrust have been set on F1 to about 1 1/2 and 2 degrees respectively". If you have a cowl the best way would be to set the fuselage up level on a flat surface with the cowl in place and measure the centre of the spinner location above the surface, then transfer that height back to the fuselage F1 location. The engine mount centre needs to be about 1/8" above this if you use 1 1/2 degrees of downthrust. If you would like the Marvic build and trimming books just PM me your address and I'l pop it in the post. It might take a couple of days as I'm reliant on my daughter running errands for me for another two weeks. Quote Link to comment Share on other sites More sharing options...
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