Steve biplane

Thanks for the replies guys.  It is like YakMad says, I can rock the rudder servo arm noticably more than, lets say, the throttle servo arm.   Control of the aircraft is ok  (or more likely I'm not good enough to notice the difference!) and I wouldn't do anything about it except that I can hear something buzzing on the aircraft during a slow pass and, being the cautious type, I'd prefer to fix the problem before something lets go. The first thing I did was check the hinges on all the control surfaces, all ok.  On ground running I've noticed that the rudder can vibrate when the engine is run at somewhere around 1/3 throttle and it produces a similar noise.  If I hold the rudder servo arm there doesn't seem to be any slop in the linkage back to the rudder so I think it's a servo problem.  Anyway, a new servo is going in so I hope the problem will go away.  I will also treble  check the linkages for slop at the same time.   YakMad, do know the number of the Hitec standard servo to which you refer? I assume Hitec servos are compatible with Futaba radio gear?   Thanks again, Steve 

David, Thanks for your reply.  My Travel Air has an LA46 up front so I don't think it's overpowered.  In fact it seems like a nice match and has achieved what I wanted which was to start learning some aerobatics.  Steve 

After about 5 hours air time my Travel Air developed a 'funny noise' .  On investigation this appears to be because the Futaba S148 rudder servo has worn bearings (and possibly output gears).; it was new servo when fitted. The result is that the rudder has a small amount of play around the neutral position.  It  looks like the elevator servo, also an S148, is developing the same problem.  Can anyone suggest a more robust servo of the same size?  Do I need ball bearing supported output shaft?  And suggestions that are not going to break the bank would be especially welcome! Regards, Steve 

Hi all, I've now covered my wing (dark blue underside, white on top) and I'm reasonably happy with the result but I could do with some tips for getting a straight line between the colours where the top covering overlaps the bottom covering at the leading edge.  On this model I will cover the somewhat wavy line with a strip of black solartrim to hide it but I'd like to do a better job on my next model.  Thanks in advance,  Steve 

Thanks everyone for your input, and good ideas. Sorry not to reply sooner but I've been away from my computer for the last week.  Regards, Steve 

I'm looking for some advice on the best way to solarfilm a wing with ailerons.  Do I :- (a) Fit the ailerons first and solarfilm around them (sounds fiddly to me). (b) cover wing and ailerons seperately then hinge them together. (c) fit hinges to one side, then cover both, then attach the aileron to the wing.  Thanks in advance for your help, Steve 

Thanks Eric

Hi,  as a recent returnee to this hobby I have noticed that a lot of modern model gliders have a wing planform which is (a) a straight trailing edge at right angles to the fuselage  (b) all the taper on the leading edge (c) curved rounded wing tips.  Which leads me to my question :- "Are there good aerodynamic reasons for this wing shape or is it just the current fashion?".   Regards,Steve.

Peter,  Thanks for the quick reply. Steve

Peter, your Werewolf design and write-up took me back 40 (good grief!) years when I built a C/L 334G (I'm returning to hobby as I work my way up to retirement).  I'm thinking of getting back into building because (a)  I'm not too happy with the build standard of artf's and (b) I used to enjoy it.  Werewolf would be my second R/C model. When you say add flaps would that be split flaps (just the bottom surface of the wing moving down) or flaps  where the whole of the rear wing section tilts down?  And what angle should they droop? Regards, Steve 

Dave, the original model used an 35cc OS BGX It was in the Dec/Jan  1994/95  vol 11 no 1  RQSA Steve 

Frank, look at the right hand side of this web page. You will see a blue block flashing '3000 plans'. It's the bottom block. Click on that and it takes you straight into the plans webpage. Steve 

Are any of these flight simulators realistic enough to allow me to learn how to do 3D aerobatics? 

Try leaving a message for contacts on :- www.controlline.org.uk

Excellent special issue - plenty of informative articles. I especially liked the explanation of 3D flight manoeuvres. Returning to the hobby at the wrong side of 50 I'm not sure I'll ever be able to stir the sticks well enough to perform any but I'd be interested in giving it a go. Steve (Off to the Midlands Model Engineering Exhibition soon to pick up some material to try making Mark Lubbock's Midge diesel as a winter project - another first if I can manage it). 

If any ARTF manufacturer wants to know what a set of assembly instructions should be like then take a look at the Black Horse 'Tutor 40' - they are very good.  So then I bought Black Horse's 'Travel Air' as a second model and those instructions are poor! 

Alistair, glad to hear your wings are still on so far. It's not so much the top speed your model reaches that will bend your wing joiners but how hard you pull back on the stick when you are going at speed. Punctilio Model Spot in Hinckley (leicestershire) stock the Robbe range and might be able to sort you out an official joiner if you should want one as strong as possible. Erfolg, the two wing joiners, one above the other, will only work if connected by a shear web. Think of an I beam with the top and bottom flanges connected by the web. The web doesn't have to be too substantial (some heavy lorry trailers have a couple of I beams running the length of them as the chassis and they often have large cut-outs). If the shear web is absent then two wing joiners will just give you double the strength and stiffness of a single.  I like the flat section 'blade and box' joiner because it is not only a reasonably efficient shape to carry the load but fixing the flat box to the wing spar is much easier than a tube for piano wire. By the way, if you think the joiner is too strong then you can take out a bit of weight without reducing the strength too much by drilling a series of holes along the centre-line of the joiner. In a previous post someone mentioned a 12mm deep joiner, in which case I'd recommend a series of 6mm diameter holes at 10mm between centres. That would leave 3mm of metal either side of the hole (top and bottom) and 4mm of metal between the holes on the centre-line. Steve (who is now off to make his sarnies 'cos guess where I'm going tomorrow).

The (yield) value that is quoted by stubs (for silver steel) is 35-50tons/inch^2 which converts 540-772 MPa not 323 Mpa. . I think the yield value quoted for piano wire (2000MPa) is a bit optimistic for the 5mm diameter wire referred to in Alistair's question. Piano wire gets its strength from work hardening and as the wire diameter increases it becomes difficult to work harden the core without overworking the outside layer. So the UTS and the yield strength depend on the wire diameter. For very thin wire (say 25 swg) UTS is about 2400MPa and the yield is not far off this value. For 3swg wire (0.25 inch approx 6mm) the UTS has dropped to around 1200MPa and the yield will be below this and by a greater percentage than the thin wire. It is difficult to be too accurate about this because the yield data is not usually quoted (although if someone has it then please share). . My overall view on Alistair's qustion is that the 5mm diameter silver steel wing joiner is probaly somewhere between 50% and 70% the strength of the piano wire equivalent. . That begs the question, does it matter? Well you could do the stress analysis but you would still be left with the answer that the piano wire could take 1.5 to 2 times the 'g' load that the silver steel did. But we don't know very accurately what those loads are so we don't know if the weaker joiner is strong enough. . The other way of looking at this is that the joiner is probably over-engineered and the most likely place for the wing to break, if it was over-stressed, is just outboard of the joiner. . So I would go ahead and fly it but take it easy on the elevator at first then, after landing, check there is no permanent deformation of the joiner. Gradually build up the 'g' levels (and your confidence) with subsequent flights checking the joiner regularly, if the dihedral has increased when you land then you have over done it! . Steve

A good question Alan, it is one I've asked before but never got a satisfactory answer to. I'll follow this forum topic but will not get up my hopes of you receiving a reply which will allow you to calculate the required servo torque in a given situation. . I think published plans ought to state on them the size of the servos required in the various positions (or what the designer found satisfactory). I'm not asking for the make and model of the servos just the torque rating. Steve

In the book I referred to there is a copy of AOH's receipt (1949) for £25, for the purchase of G-AFIR which bought him "a pre-war registration which had flown and a highly unairworthy airframe attached to it". Another receipt in the book, from 1963, is for 4 gallons of fuel (total cost one pound and tuppence) given when AOH dropped into Heathrow to refuel. Can you imagine the chaos that would create to flight plans these days. Steve.

Silver steel (also known as ‘drill rod’ in the US) is a steel containing about 1.1% carbon plus small amounts of other alloys to help with the heat treatment. It is intended to be used for producing tools. . It is supplied in both metric and imperial sizes and is very accurately ground to diameter. It is most readily available in 13 inch lengths but can be obtained in 1 and 2 metre lengths as well. . It is supplied in the annealed condition so it can be sawn, filed or machined to the shape you want before heat treatment. . The heat treatment calls for heating it to 770/790 degC (cherry red), hold it at that temperature according to the 1 hour per inch diameter rule, and then plunge it into cold water. This makes it rock hard and brittle so you then have to temper it by heating to between 200 and 300 degC depending on what you want to use the tool for. For more details look at a book aimed at model engineers. . The aeromodeller can use it in its 'as supplied' state where it is a steel with a tensile strength of about 45 tons per square inch. This is at least 50% stronger than mild steel but nowhere near as good as piano wire. . Where it might be useful to us is if you have a structure that MUST be silver soldered to take the loads (the cabin of a Fiesler Storch perhaps). This is because if you allow the silver soldered joint to cool slowly in air (don’t quench it) then you should still have a steel capable of taking 45 tsi. Steve

Peter, I wonder if most clubs must have an 'engine expert' like that. When I turned up at my club with my new trainer the LA46 was pounced upon by the club expert who flooded it to the extent that it wouldn't start even with an electric starter. After he'd got bored and pronounced it 'the usual OS rubbish' I took it to the corner of the field and figured out the starting routine for myself (I'd had a few diesel engines in my youth). The result is I can get it to start within 5 flicks (usually 2 or 3) without fail. Steve

Richard, If you have an interest in Luton Minors then you should read 'On Home-Made Wings' by Arthur W J G Ord-Hume. Amongst other things it relates his trials and tribulations getting Minor G-AFIR back into the air around 1950. A good read that's still in print or get it through your local library. Steve

Peter, I agree but in his post preceding mine kdc says "The 1/32 or 1/16 ply can also be cut with a Stanley knife." and that is what I was referring to. (and let's be honest haven't most of us done it at some time or other) but that doesn't mean we should advocate it. Steve

All, If you are going to cut 1/32 (0.8mm) and 1/16 inch (1.6mm) thick ply with a Stanley knife then take care because there is a tendency press down very hard and you lose control over where the knife goes if (when) it slips. Lots of cuts with less pressure and slowly cut your way through is the way to go. Better still, if it is a straight edge you are cutting, then use a razor saw. Steve, who sits back and awaits replies from anti-H&S brigade.