Terry Whiting

Simon.   I assumed the twitch was aileron, but I see now it's pitch twitch, so you could well be right with your assumption of a rearward balance point. Still it's nice to know she flies, and will be great once trimmed.   TW 

HI Geoff,   I think Mario infilled between each stringer, I marked the area, and removed 1.5mm off the stringers, then sheeted over with 1.5mm sheet. Once dry I cut a 13mm observation window.    Edited By Terry Whiting on 20/02/2010 15:59:56

Simon, I'm really pleased for you. I see you did make provision for a rudder, did you have to use it? I suppose being  twitchy could be due to  the lightness, and the amount of aileron  control surface to model weight.  It might be worth trying rudder only, this I think would give some indication to the power of your ailerons, and may be the need for reducing their overall travel.   My little Widgeon which is about 3oz heavier is surprising how little rudder movement is required in the turn.   Just  thoughts.   TW     

Hugh,   Up until I sold off my I/C models most of my engines were Laser, and the only gripe I had with the Laser was the position of the carb, but that didn't alter the fact I  my Lasers.  I put this question to  Mr (Laser Engines) Neil Tidey at a Club talk he was giving. The answer was the carb most is  most efficient directly into the head, that is the reason why formular 1 cars have individual carbs fitted directly to the head.   Well as many Laser owners know this can lead to syphoning, my answer was, if I couldn't fit the tank low enough, I positioned the engine at  9 o'clock (sidewind)  and ran the servo push rod along the side of the tank,  fitted a bell crank in the cowl, and readjusted the carb throttle by 90 degree.   I personally think for the Lizzee you are OTT for power. My L 70 was flying a 8.5lb bi-plane on floats, and even then I only needed full power to lift off the water.      

John,   What a transformation, that cowl looks handsome.   I like your tape idea for fixing the ABS. Strangely enough this weekend  my son gave me a roll of automobile double sided tape, the type use for door tims. "Just might come in handy for the models dad" said he. Well it's not might, but will.   Why I sugested Flexi Bond because I use if when attaching aluminium flying wire anchors  in bi-plane wings, or dressing aluminium cabanes with 1/64" ply to make them look solid wood, and gluing lithoplate over balsa.    TW.      

Mario,   I think I may have been over cautious about that aluminium U/carriage as have never use aluminium of that grade, I have always use either piano wire or Dural.   As for attaching the ABS leg to the aluminium I'm using EVO-STIK  Flexi Bond which is an extremely strong flexi adhesive.  At the top of the leg nearest the fuselage two soft balsa blocks will be attached, one  either side of the aluminium with Flexi bond, and again just above the wheel spat. These blocks will then be sanded for a snug fit inside  the ABS. Once satisfied I   add my landing light wiring and wheel axels, then adhere one side only of each the ABS leg. 24 hour later the other side will be added.   Leaving that curing time will alow the other half of the leg to be fit with no fear of moving the first half.  Flexi Bond will also make a nice fillet between undercarriage leg and fuselage.     Hi M.T.   Yes my fin is built up with just  four 1.5mm ribs and 1.5mm sheet , the same goes for the tail plane. Reason for the weight saving, mine is electric as is one or two of the other guys who contribute to this blog       

Simon,   I think we have all suffered the same dilemma in our modelling lives,  but it takes a man to hold his hand up and admit his error to the world. Hope all goes well on the next test.   TW  

Peter,  It would be if made by yourself, but surely CAD, and Laser cutting  comes at a price  

Simon,   If the model was mine,  I would disconnect the aileron servo, secure the ailerons with 4 small pieces masking tape, and plug the rudder servo in it's place. I would then test glide without radio.  If required add plasticine as ballast  until I had a satisfactory glide. If satisfied, use the height of a step ladder to extend glide with radio on and use elevator, and rudder only. If all was well my next glide I would open the throttle very gingerly.   I hope i'm not being a pain, just want to see this plane fly.   Terry        

Simon,   Sorry to hear of another failed test, but i'm pleased you are now contemplating a 'rudder'. Did the slight  negative wing incidence help, or was the flight too short to evaluate? Is there any possible means of test gliding? as this could show if the problem was/is power torque related.   Terry

Hi M T.   I wouldn't worry too much about the engine and tank weight issue, because none of the wood packs can  possibly be exactly the same weight, If you can save just 7g in the tail construction, that works out to approximately 1oz less ballast in the nose.   You have started with a lighter engine,  just see if you can save weight in the tail end to compensate, I'm sure you can.   All the best with your build.   Terry

Hi Jim,   Pleased for you,   you know the old saying  "practice makes perfect"   When it comes to the actual job of hinging, do not try to do the complete job in one hit. I always do the moving surfaces first,  make sure the epoxy is well coated inside the slot, and clean off the face surface before adding the hinge. Then let them cure.    Do not forget the vaseline    For my ailerons and flaps I will be using strips pieces of the covering material as the hinge. If you would like to know the method I will add it to the blog.      Terry  Edited By Terry Whiting on 17/02/2010 08:50:13

Simon,   Have you thought of GWS Hyper Drive props, I have used them on small models, and are very forgiving. Being extremely thin and flexible I replace folders with them. BRC are doing a good range of them.  

Hi Jim,   Really it should not be necessary to dowel pin a hinge, if you take  time and care in the  gluing, that should be quite sufficient. Kavan and Du-bro flat pin hinges have 4 or 6 glue keying holes in each half of the hinge, but if you feel you must dowel just use a piece of cocktail stick.   Prior to gluing any hinges or ABS, I wipe first with Isopropyl Alcohol, this is incase a release agent has been used in the manufacturer. (Isopropyl Alcohol can be purchased at most chemists, you may be questioned on it's use)      Just try gluing a hinge in your test piece, use a slow cure epoxy NOT 5 minute. Leave it  for 24 hours and see if you can pull it out with a pair of pliers. I think then you will realise dowel pinning through the hinge is unnecessary.      

Geoff,   I have my doubts about the advise you were given in being able to reshape cured Carbon material with heat. I thought if this was possible, why would manufactures of cabon fibre undercarriages bother to produce a moulds.

Simon,   Would those 10mm wide pin hinges be of use, they are extremely thin, I have used them in 3mm balsa, but I have no dealing  with depron.

My favourite is always the one I have on my building board.

Allan,   One thing I forgot to mention if using this method care is needed when gluing  the cases together to make sure they are the correct way round.   I think you are right about the wiring.

Hi Alan,   I have only just spotted your thread.   Yes the plugs  are quite neat, but I have already made mine. I took the four outer cases off a pair of Y- leads, S/glued two pairs together flat sides together, then mounted them through two piece of 1/16" birch ply which spans F4 & F5. The hole was made for a tight fit for each pair then S/glued. My Y-leads will run down each side of F5, and taped with aluminium self adhesive, then painted over. My aileron and flap leads will extend about  2"  through the wing root, but will easily slide back as the wing is pushed home as I always build in 1/2" paper tubes for my wiring.   Page 12 of Jim's Lysander build shows  my wing and it's Paper tubes.     Nav lights mine are for show, but by painting two LED matt white, then over painting with  Fishing float Dayglow Red & Green  paint looks very affective on the ground.       

Simon,   I understand, but in my book that has always been  positive tail plane incidence, but you did have me worried.    

Simon,   Truly hope all goes well Friday.   As for a touch of negative incidence on the scale Pup tail plane, isn't that going to accentuate the problem,?  

Mario,   You gave JIm the answer in the use of Mylar which I didn't,  as I'm somewhat anti Mylar,  I suppose I'm too old for change.   I have read in one of my aircraft magazines that there is a light full size aircraft  using a similar hinge.   I think I would have been rather concerned if that hinge  was on the aircraft I was having lessons on.   

Hi Jim, I can answer for Mario. Yes they are proper pinned hinges used on aileron and flaps, and Mario used Robart dowel hinges on rudder and elevator.   I use KAVAN, they have two sizes 20mm width, and  16mm. I would suggest the 16mm, the 20mm I only use on 1/4 scale models.   DU-BRO make a similar hinge.    When I  fit pin hinges for surface mounted, I build in the hinge blocks in both wing and aileron, then  mark my hinge positions. I cut the slot  1/16 (1.5mm) below the wing surface downward at about 45 degrees, the knuckle of the fitted hinge will then be level with the wing surface. (this is where my mini saws are  very handy) I then cut a piece 1/16" square (1.5mm)  and glue lengthwise between the hinges, once dry lightly sand to the level of the wing surface, this give a gap free ailerons and flaps.     Alternatively you can notch the hinge knuckle into the wing and control surface.   I know many modeller swear by these mylar flat things, but personally I think them a poor substitute for a proper hinge.   When fitting pin hinges always wipe a smear of oil or vaseline to both sides of the hinge knuckle, this eliminates glue penetration.Edited By Terry Whiting on 11/02/2010 10:30:23

Hi Simon,    To be quite honest the profile picture gave me the imression you had been a little extravagant with the + incidence. If that was the case, and you were tempted in breezy conditions  I could imagine the flight being nose upish and wallowey, with next to no control with ailerons due to flying practically in continuous  stall , which would naturally drop wing as you came back on the throttle. This is why I suggested adding a rudder to the test model, ailerons are virtually ineffective flying near to the stall, and only exaggerate the problem.   In the profile picture it was impossible to see if you had included any down thrust. This could have been another factor.   You know the old saying Simon, if you think you have more than one fault, correct them one at a time, to do them together and she flies, you still do not learnt what was the actual fault.         

Mario,    Yes that is the hinge centre  guide I have seen. I made one vertually the same a few years ago from aluminium strip, it's still in use.  I'm bit of a model tool gadget maker, one of my favourites I made is a pendulum wing incident meter which must be 40 plus years old and still in use. It can give incidence to the nearest .25 degree. Sorry, I'm getting a little carried away here.   As you rightly stated, if painting your method is prefered, but I have in the past tex covered and painted without a problem, mind you It was never with gloss paint only with  matt.