Garry G Posted February 9, 2012 Share Posted February 9, 2012 About to start building, BB plans are not revised for R/C - any suggestions before I start. Think I need to reduce the diehedral and increase the fin and rudder size. Garry G Quote Link to comment Share on other sites More sharing options...
Martyn K Posted February 9, 2012 Share Posted February 9, 2012 Hi Garry Are you making it Radio Assist or Radio Control? M Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 9, 2012 Share Posted February 9, 2012 Hi Gary, I'll take a few pics of mine a little later on today and let you have a look, The only mod I have done is to reduce the wing incidence from + 4 to around +2 degs, Mine is three channel on Rudder / elevator and throttle, powered by an OS10 JIm. Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 9, 2012 Share Posted February 9, 2012 Gary, Found three pics on the m/c This her ready for the test flight along with another free flighter called Redskin Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted February 9, 2012 Share Posted February 9, 2012 Hi Garry, Looking forward to this build an absolute classic model. Jim, They look so cool, love the free flighter. I've still got an original Slicker in the loft not built yet and a Mills 1.3 to go with it. Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 9, 2012 Share Posted February 9, 2012 Garry / Chris The big problem is getting the c/g far enough forward,even with the OS10 up front and the receiver pack split and epoxied in place under the chin I had to make the nose ring out of lead sheet. I remember now,when I first built it I removed all of the positive incidence thinking we have elevator control so no problems ----- It would not rise of the ground,it flew from a hand launch but very sensitive on both rudder and elevator. Made a wedge for the wing seat which gives about 2Deg. + and have never had the chance to fly it due to this and that and the weather. Jim Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted February 9, 2012 Share Posted February 9, 2012 Hi Garry, Looking forward to this build an absolute classic model. Jim, They look so cool, love the free flighter. I've still got an original Slicker in the loft not built yet and a Mills 1.3 to go with it. What have you used for trim. Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 9, 2012 Share Posted February 9, 2012 Fuz is Red solartex and the wings and tail end are natural tex with Wilko bright red paint for trim. Quote Link to comment Share on other sites More sharing options...
Guest Posted February 9, 2012 Share Posted February 9, 2012 Gary, I built a Mercury Mallard - ie a competition model similar to the slicker . It had a rearward CG to give reduced wingloading with the tailplane adding to the lift and improve glider performance. The design is based on a short highpowered straight up flight for height and then turns into a glider with a fairly tight turn to keep the model in thermals if it hits one. My mallard did all that OK but of course it drifted downwind, whereupon I applied RC to straighten flight and bring it back upwind. Now the rear CG comes in to play and the model goes into very bad stalling only cured by application of massive down and loss of height. From this I learned that for reasonably stable RC, I needed to bring CG forward from the 85% rear position and this was only achievable by extending the nose substantially and also reducing tailplane size, Re dihedral - i think the model will need it all if you stick with the current design. Of course - it may just have been me and not the model ??? John Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 10, 2012 Share Posted February 10, 2012 John, From your post it looks like I need to get the C/G further forward to reduce the sensitivity of the rudder and elevator. major job if the nose has to be extended at this stage,when I get to try it again I will have some C/G ajustment ready to tape to the underside of the chin to see what difference it makes. When you mention dihedral did you mean Wing incidence, I have the dihedral set as per plan.Jim Quote Link to comment Share on other sites More sharing options...
Guest Posted February 10, 2012 Share Posted February 10, 2012 Posted by Jim Carss on 10/02/2012 10:16:12: When you mention dihedral did you mean Wing incidence, I have the dihedral set as per plan. Jim Jim, dihedral is usually taken as across the wings ( I forget the proper name ) whereas longitudinal dihedral involves wing incidence vs tailplane incidencewith +ve usually the case for stability- ie reduced stalling habits with self correcting built in from your question, I take it that, in your first post you meant longitudinal dihedral - if so then I believe it should be increased if you shift the CG forward by much. The competition boys can probably give better advice from their experience but my reading of the pylon,rearward CG and large tailplane design was to obtain maximum lift from all surfaces to extend the glide ( to win competitions ) by rear cg and large lifting t/plane while balancing the glide characteristics with the screaming 10 sec vertical climb for height. The need to keep the t/plane lifting would result in reduced longitudinal dihedral between the wing and the t/plane but this would give reduced stability and if model starts stalling , the stall would get worse. This was resolved by fairly large polyhedral ( across the wing ) and trimming for a fairly tight turn as the model peeled off the climb into glider mode, which also has the effect of keeping the model in thermals ( or downdrafts -which ever they hit - which is why you see comp boys watching their thermal indicators getting ready to launch into lift ) The above is what I learned from flying my RC mallard - any attempt to fly straight needed kid gloves on the elevator to keep speed just right - difficult as not only is the model moving but the air is as well. One of my best flights was during a very calm day ( a rare event ) when i just let the model fly in circles with just the slightest of touch on rudder to keep overhead. Of course my mallard experience may just be down to my flying ability plus my accuracy of build vs the model design johnEdited By John Laird on 10/02/2012 20:19:40 Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 10, 2012 Share Posted February 10, 2012 John, You dont want to buy a Slicker 50 by any chance. good price for cash English money I'll have to digest what you say ,give it another try and see what happens awful complicated this flyin bizz. Jim Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 10, 2012 Share Posted February 10, 2012 Question, Where is Garry.??? His thread and no response !!!!! Quote Link to comment Share on other sites More sharing options...
Guest Posted February 11, 2012 Share Posted February 11, 2012 Jim, I didn't want to put anyone off - just to warn them. See how your slicker goes and if it behaves like my mallard, try building a small lighter t'plane that will shift the cg forward john Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted February 11, 2012 Share Posted February 11, 2012 I haven't any experience with smaller models but my Southerner Major (84" w/s, os 52 4stroke) has the c of g at about 70% back from the leading edge, from what I gathered many years ago the reasoning was that a lifting section on the tailplane counteracted the rearward cg. The proof of the pudding etc, when built my southerner had a 30% cg, landed at high speed and had a steep glide angle, it wouldn't soar very well. A friend of mine had the original plan and the c of g was shown (well actually shewn ) as being at 60% iirc. I started there and worked back. I took the best part of 12 ounces of lead from the nose and the model now lands at walking pace, thermal detection is excellent and I appreciate the fact that the OS can idle up to 10 minutes (even being inverted) then respond with only a minor hiccup and clouds of smoke - the latter is ideal for re-establishing eye contact if I lose sight of it as I have once or twice as the arthritis bites into my neck......HTH soft southerner, wild c of g dept. Edited By John Gibbs on 11/02/2012 10:09:27 Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted February 11, 2012 Share Posted February 11, 2012 Following on from my earlier post, this reaward c of g doesn't work with flat plate or symmetrical tailplane sections, eg my falcon, J 60 and windy aint it which all have a c of g around 30%, there is a clark Y lookalike on my super scorpion and, iirc, the c of g is about 60% on that, haven't flown it for a couple of years so can't remember too well. Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 11, 2012 Share Posted February 11, 2012 John, The other model in the photo is called Redskin deigned by Pete Holland and it flies a dream,c/g around 30% I was so impressed with its performance i scaled it up to 66" span with os 40fs and it flies even better. I also have a super scorpion with os20 up front and it gos well. Quote Link to comment Share on other sites More sharing options...
Garry G Posted February 13, 2012 Author Share Posted February 13, 2012 Sorry for the delay in responding to all your replies, have been rather busy but many thanks.Lot of information here to digest but will reply a.s.a.p. I have a Playboy Junior which I fly in our club's Vintage competitions and this is where it all starts, it is a club model and has been the subject of the mods. I mentioned in my posting. The Slicker will need full R/C to take part so elevator and rudder servos minimum. RegardsGarry G Quote Link to comment Share on other sites More sharing options...
Garry G Posted February 15, 2012 Author Share Posted February 15, 2012 Jim, your photos are very useful, I intend to install an electric outrunner and will have to extend the nose to get the C.of G. as per the plan. Looking at the front view I think I will fit the bearers as shown but longer and mount the motor on a new firewall that will fit over the bearers and slide up and down to find the right balance point.Do you know the weight of your Slicker?I can see the elevator on your photo, did you make this solid and does it extend up to the "finlets" on the underside as shown on the plan, also is the rudder that solid part on the photo? John LI will build the wing and tailplane with the incidences as per plan, +4 deg.on the wing and +2.5 deg. on the tail and see what happens. Altering these is a bit out of my comfort zone. Reducing the dihedral slightly on my Playboy was suggested that with the introduction of Rudder and Elevator control the addition stability given by the original dihedral was not needed and could induce Dutch Roll. Not that I would known what that was if I saw it !! Any further thoughts? John G Some of those C.of G. positions seem very far back, one of our club members has just finished a Falcon so I will see where he has his.What does iirc mean ? is that text speak Garry G Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 15, 2012 Share Posted February 15, 2012 Garry I'll take some pics of the rear end this morning for you. Jim Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted February 15, 2012 Share Posted February 15, 2012 Garry, iirc is if i remember correctly. I sent a second response identifying where the rearward c of g would work. Iirc the slicker has the same flying surfaces as the southerner and you should be able to move it back in stages, generally speaking you will achieve this by removing weight from the nose as, by and large, they need lead to bring the c of g forward to the 30% we normally use nowadays. Btw, aero-modelling isn't just about building and flying, the experimenting in getting the best out of your model can give a buzz too. These old models were designed effectively as powered (sometimes overpowered) gliders and often were designed to fly near the stall. I'd say approach the comments I've made with an open mind, the mods work for me and they worked way back when. The models will fly with the c of g at 30% it's just I hold the opinion that they fly better when adjusted as I've said. The system also works on modern stuff too, I bought a radian 3 channel, with the c of g at the rearward point of the instructions she still flew relatively fast and the glide angle was not what I expected so I shifted the battery back as far as I could and the cg ended up about 15 mm or so back beyond the recommended range, it transformed the model, flight times are only restricted by my arthritic neck. It boldly nods when it hits a thermal or downdraught and flys so slowly that for the first time in my life I can actually fly it back to me and catch it instead of landing it. I made this adjustment based on my experience with my vintage models. Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 15, 2012 Share Posted February 15, 2012 Garry Garry,it weighs in at just a tad under 2lbs,jus checked the c/g again and its way back 2 1/2 " from the trailing edge,looks like i'm building a lighter tail end for it,aint no place left to add weight to the nose. Jim Quote Link to comment Share on other sites More sharing options...
Garry G Posted February 19, 2012 Author Share Posted February 19, 2012 Jim, thanks for the additional photos, the elevator is where I thought it should go. On the rudder the hinge line looks vertical as I would expect, did you have to redesign it as it looks different to the plan which has a distinct forward slope? I will try an mount the servos forward nearer the C.of G. if possible to help the balance. Roger Stanton has a regular column "Nostalgia Notebook" in the BMFA NEWS and in this quarters edition inlcludes a piece about a Slicker 50 built by Martin Rudgley. His model weighs 22 ozs. against yours at 2 lbs. but he has fitted a KBM 31/12 bell motor which may account for the lower weight. Originally used a 7 cell nicad but was under powered but now has Lipo's. He also extendednthe nose by about 1". I will fit a BRC 2212-10T motor in case mine weighs nearer to yours, best to have a bit of power in hand. John, thanks for your reply, the C.of G. on the plan is shown as 50% of the chord, apart from the necessary mods. for the elevator,rudder and motor I will build my Slicker as per plan. Garry G Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 19, 2012 Share Posted February 19, 2012 Garry, Mine is now in the bin, unable to add any more lead to the nose to bring c/g forward so it looks like a new fuz with extended nose sometime in the future. Jim Quote Link to comment Share on other sites More sharing options...
Jimbo565 Posted February 19, 2012 Share Posted February 19, 2012 Garry forgot to mention I did increase the size of the rudder Jim Quote Link to comment Share on other sites More sharing options...
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