Tony Patman

Well my problem was that the model was back-heavy, and the amount of ballast required in the nose to compensate would have been silly.  I didn't make any changes to the construction of the tail except to reinforce the flimsy fin with some ply.  It's still not a problem I've solved, and I haven't had time to do any modelling at all over this year.

Yes, Russ.  Source the aluminium tube very carefully.  Get the lightest one you can.Plan exactly how you are going to fit the engine before drilling any holes.Erm...let me think some more.  It's been a while...

Doh, Timbo, this one's been doing the rounds for years.  It's still funny, though.

Thanks so much for all your help.  I can't wait to see some pics of you in your frocks

Thanks so much, Erfolg: excellent, detailed advice.  What's a "scarf joint"?

Upon closer inspection, there's more damage than I thought The trailing edge spar is cracked at the inboard aileron hinge position, which is hard to get to without more substantial destruction of the wing; and I suspect just filling the crack with epoxy would not be satisfactory.  Hmm.  I might shelve it and focus on getting my new model balanced and in the air.

What a world of coincidence we live in

I'm not, Myron. Scarborough...

It strikes me that Mike Ward must have been well-known in the UK modelling community.  I wonder if we can canvass old hands on here to find out more?

I've just tracked this web site down.  It says "Model flying commenced at 'Goosedale' in 1989 and shortly afterwards the 'Goosedale Flyers' club was established. The name was changed to 'Leen Valley Model Flying Club' following the death of Mike Ward, founder of the Model Aviation Museum (which was internationally renowned as a center of excellence for model flying).  The site is now a private residence, and we continue to fly at Goosedale by kind permission of the owner, Mr G. Hayer." So there you go.  Maybe a topic for an RCM&E retrospective feature, Mr Ashby?  Might be tough to research, though, since Mr Ward is deceased.

Incidentally there are some impressive medium-sized models of WW2 British bombers in the café of the Yorkshire Air Museum at Elvington.  They all appear to be IC powered, and I don't know if they are still radio-equipped or airworthy, but I recall Lancaster, Halifax and Stirling being represented.

Thanks chaps.  The break is near the root, erm, three or four ribs out from the middle from memory.  The fact that the stresses are higher near the root is why I'm here asking!  I thought of repairing using a piece of hardwood rather than a piece of balsa; and I note Bruce's suggestion to add a doubler too, which seems wise.  I had hoped to avoid removing all the covering and replacing the whole spar.  I know what I need to do: take a picture and post it on here!

Following a crash of my Tutor 40 a couple of weeks ago, I'm getting to grips with repairing the damaged wing.  A hedge impact broke through the balsa skin of the leading edge between two ribs and severed the upper spar, which appears to be 1/4" balsa, at the very edge of a rib.  There doesn't seem to be a solid leading edge, indeed.  The back of the D-section was also cracked, so the shape of the wing is currently relying only on the lower spar.  If I can rejoin the broken spar, replace the back of the D-section and reskin the leading edge, I think all will be airworthy again. So, oh gods of balsa, any tips?  I was going to try a splice for the spar, carefully cutting a very shallow V shape along it and epoxy-gluing a new section into the V, positioning the V such that part of the depth of the original spar which is still glued into its slot in the rib remains.  The spar seems to be the critical structural element here: the other bits are trivial.  So, am I on the right lines?

Re. flight simulators.  You could pay £20, or you could pay nothing and get FMS.  OK, you will need to buy the right cable to connect your transmitter to your PC, but these are available from a number of suppliers. Apart from all that, I have to say that I agree with Eric.  You can't treat these things like toys: people lose fingers just starting the engines.  If you join a club you'll be insured, have a prepared site to fly from, have access to a ready-made crowd of knowledgeable supporters and almost certainly someone who will help you not to crash the thing by doing the difficult bits (taking off and landing) for you until you've got the hang of it.  All sounds a bit daunting and maybe a little hysterical, I know, but trust us, you'll be making your life much easier!

I'd love to build a small model of this apparatus to see how much burnable fuel it produces over time: is it enough to supply a small engine continuously?  If it generates at a continuous rate then that would have to be sufficient for maximum power, but how would you throttle back?  Vent the surplus?  Store it somehow?  How does its power-to-weight ratio compare with glow or petrol or electric power?  How much power does it need to crack the water? Oo, interesting.

Has anyone tried or seen an attempt at a flying model airship?  I don't mean some glorified balloon, I mean a scale model of R101 or a Zeppelin or something like that, with engines and control over attitude and buoyancy.  Mass, I would imagine, would dictate that success could only occur on a calm day.  I wonder whether the quantity of helium needed would be affordable?

Myron, I think I've found the right thread, and I can see where you refer to an "attached" document, and I think I need to email you for it, so I will do that now!

Crikey, Myron, you're a real evangelist for this.  It does sound very interesting, and I will definitely look through the information you've made available.  Anything with a decent power-to-weight ratio is worth considering, and if it is a clean technology, all the better.  I doubt the CO2 from glow-fuel model engines is significant next to that from cars, trucks, power generation, shipping, aviation and industry in general, but I do agree with you that the modelling fraternity is well-placed to explore and develop new energy technologies.

Hi Chris.  Well, I improved the ventilation by unblocking the light-well (which had been sealed with paving stones on top) and installing an extractor fan in the window, but it's still damp enough to make my tools go rusty.  I haven't noticed any particular problems with it penetrating models yet, but we'll see.  The radio I have down there seems to be fine too, so I guess your damp must be damper than mine! 

You're right, Myron: people tend to pile in with their pre-conceived ideas and flimsy assumptions before they've read up properly.  When you say "our" model engines, do you mean the RC modelling fraternity or some company or organisation with with you are involved?  Water power sounds intriguing, but I thought water couldn't be compressed?  Wish I was a mechanical engineer, not just another desk-jockey...

OK so I'm the only one who finds this interesting

My workshop's a cellar too.  Damp makes my tools go rusty .  Nice long bench, but can I find a stool to sit on anywhere?  I've been to every 2nd hand shop in Scarborough, not a stool in sight unless I want to sit 6in off the floor.  Still sitting on that camping chair.  Shiny new band saw and bench drill fresh from Aldi...let's see how long they last at £40 and £35 respectively... It's a cluttered tip, but I try to keep on top of it.

Tentpeg, I hope you find someone who wants your plugs.  Indeed, Ebay might be the place for them otherwise. Now THAT is intriguing.  Please may I have one to play with?  In fact, it's so interesting, I'm going to start a new thread about it.  It's not a Wankel, but crikey, it's cunning. Incidentally I always thought that a rotary engine was a radial engine in which the crankshaft was fixed and the cylinders rotated around it...

This thread is sparked from some confusion which arose in this other thread concerning whether a Wankel engine is a rotary engine. Anyway, during the discussion, Richard Bond referred to a cunning, novel design for a full expansion cycle engine. I've never seen anything like this before, and I thought it warranted a thread to see if anyone's got one, seen one, tried it, wants to. Maybe this is all common knowledge amongst the cognoscenti on here, but I'm fascinated anyway. The diagrams and animation indicate that this is not a Wankel, although the outward appearance of the crankcase does make it look rather like one. It's claim to fame is that it is the "first practical full expansion engine. True full expansion is achieved when gas expansion continues inside the mechanism to a final volume 3.5 times the original swept intake volume. This allows the gases inside the engine to reach atmospheric pressure. The full expansion process uses all the available energy to produce work. This results in a cool exhaust without any exhaust blow down noise." So how does it do it? Well, it has combustion chambers for both high and low pressure, with the initial bang taking place in the primary chamber and then being ported to the secondary one for further expansion all the way down to atmospheric pressure. That much is not new in principle; well, maybe as applied to glow engines it is, but the idea's been used in steam engines for a very long time, with high and low pressure cylinders. The bit I find mechanically fascinating with this engine is that the primary chamber is inside the piston of the secondary chamber, reciprocating perpendicular to it. Thus there are four chambers in use. I suppose if you designed a conventional engine equivalent, it would have four cylinders, two high pressure and two low pressure; but this design cunningly wraps all that up in one chamber. Crikey. Sounds like fun. Wish I had £225 or so to blow on one. Better start saving up.

ON, indeed.  I have resisted the temptation to edit my post and cover up my mistake