A return to model building and flying. Part 59


June 2009

A Wasted Few Months

(Fiddling with RC gear)


One day I had bright idea, but as these things tend go it turned into the usual saga. What was it? Well read on.

I have often contemplated using electrical signalling down the lines to control any future carrier models I might build, but never been keen on the idea of ripping apart RC gear and having to have an insulated line with all the potential weak links in the chain of command. So have never bothered

Then a laying in the bath Eureka! moment occurred. Why not use a 2.4GHz model car outfit, the transmitters look like a CL handles, no insulated line needed, and 2 to 3 channels to play with, and no conflict with the normal RC flyers. Couldn't be easier...! HA! (the last exclamation is a sarcastic one)

Of course the legal aspects regarding competition flying would have to be sorted to, but my club had no objection, and being mainly RC orientated and conservative in some respects when it comes to legality and safety, this must speak volumes. So I had a green light to test out the theory.

My personal view is that it does not change the model or control system in any way: It is still a control line model. If the RC link was to fail completely, what the would the result be? either no throttle and and a landing, or flat out, and long boring flight. and, Oh look... the hook is down (or stuck up). Even if someone could hijack the link, all they could is play tunes on the throttle; annoying but not exactly life threatening, and you can always ditch. ANY of this is no worse or better than any other form of CL flying. This is just my opinion others may disagree, but denying it as valid form of issuing ancillary commands is like standing on a beach and and trying to stop the tide coming in. It will happen eventually.

The actual gear I used was an Acoms Technisport 2,4  0555 The instructions are basically crap, but all you do is plug in and switch on. It even has servo reversing which I only discovered by accident, and is extremely useful. The receiver is a joke, it is so small you could cough and loose it. The servos are much too big, but replacements are cheap and easily obtainable.

2,4 GHz

I managed to fit a bar across the gap between the bottom battery compartment to the a protrusion, in front of the throttle trigger, only to find that the gap between the lines would be a a lot smaller than an normal handle.. Hmmmmmm! Not only that, but after all the work of fitting it neatly into the case itself, I thought of a much easier way of doing it that would half the work. Such is life......

Next problem was altering the trigger to just give full end to end movement on the servo as cars use the forward movement as a brake, no point in it centring for a throttle, .

So far so good

I wanted all the model end equipment in a box that could be screwed onto a profile model.  The batteries were also heavy so a triple A size holder was substituted, only to have the connectors melt off as soon as I tried to solder wired onto them. Grrrrrrr!

Stupidly, a box turned out to be the biggest problem of all, I just couldn't find one the right size, the right size was juuuust to small, and the next size was bigger than need be. More Grrrrrrr!

Eventually it was all hacked, bodged, and pushed, into a case. All seemed to be looking good. That was until I got to the field.

The first problem that hit me was starting and running the engine on the ground. I need the TX next to me to fiddle with the engine. With lines attached that means means they are draped in big loop, and all the possibilities of snagging them walking back and forth sprung to mind. Not such a clever idea then.

OK, I persevered. The actual flying was a nightmare! The model was heavy to start with, with a few more grams added it became even more pig like. The throttle was almost impossible to control as the range that seemed to do anything worthwhile was during the last few millimetres of travel, OK that can could be sorted by various means, but it was not pleasant up to now. Then I realised the old reason I don't particularly like flying RC models was happening here. It's a disjointed perception of control. I can't feel what is going on as there is no feed back. with my crudest tree line set-ups, I have such fine control that I can play tunes on the engine, and know what it is telling me back. That was totally lacking with the RC link. and by now the weight of the TX batteries was telling on my flying hand, it felt like I was waving a lump of lead around not actually controlling a model.

By the end of the day I had had enough. Back home the RC gear came off and the model returned to it's normal state. And having flown it since it feels like it should do, in the sense that I am controlling it not the other way round. To be honest it felt like a weight lifted off my shoulders. What seemed like such a good idea in theory, turned out to be a bit of a wast of time (a lot of it) which I don't have much of to spare these days.

Maybe someone out there can pick up the challenge and run with it. I hope so!

Bearcat

I also started to build a Brodak Bearcat kit......!!! What sadist designed it.......??? What was on  his mind; lets inflict as much misery on the builder as possible? I just cannot see the reason behind why it is constructed the way it is, some of it seems to be done just for the sake of making it difficult to put together, I can't find  rhyme or reason for most of it, no matter how hard I try. More on this as and when I get the chance to work on it

Corsair

I am also trying to put together and modify a Great Planes Combat Corsair for Carrier. I have seen it done so I know it's possible. Because of splitting my time between running a business (and having fun) in Second Life, wrestling with things computerish, and the aeromodelling, I need to save some time on the building of models; whether that turns out to be the case; we shall see. Ironically I am building aircraft in Second Life and learning how to control the physics scripts that make them fly and behave in in cyberspace. Below an example of a steampunk inspired airship that I am working on that I have produced from the ground up with my own fair hands. 

airship SL

So far all I can say about the Corsair is, the covering is appalling, especially on the fuselage; it resembled a wrinkled prune, and took me an hour of patient work with a heat gun and soft duster to try and shrink the film without blowing up big bubbles, melting it, or putting dint marks in the wood. The covering also seems to be Toughlon which I have written about before. This would explain it's less than good adhesive properties, and the fact that the film is separating from the adhesive/pigment base in places: and I haven't even flown it yet!!. The instructions also had two pages printed in reverse, which resulted in the use of  a mirror to try and decipher one part I needed to know. Fortunately instructions not needing you to stand on your head are available from the Great Planes website. The model itself is a work of art, all laser cut and lightened. I certainly couldn't make a model approaching this sort of constructionaly accurate asembly, the sheer number of lightening holes on formers or the sheet covering of the fuselage would defeat me

Corsair

I am at the stage of assembling the kit, as is, with no modifications for controlline yet. apart from changing the elevator hinges from much too stiff Mylar ones to pin hinge ones, this is more work but I have always found then superior for stunt or carrier, where I want then to work with as little resistance as possible in an slack line situation. 

I am also not happy about having an inverted engine in a carrier model, as the lower nose of the aircraft can take a lot of punishment. Changing it to upright will mean modifying the fuselage, as the there is a neat cut-out for the inverted engine silencer which doesn't exist if you choose another form of mounting.So far the neatest solution seems to be getting hold of a manifold extension and mounting the engine on it side exhaust down, Silencers can make handy skids in worst case scenarios, and may even stop the fibre cowling being destroyed in the first heavy landing. I definitely need some form of crash cage in the cowl it's screaming out fragile at me.

So far fitting the engine and cowl has taken me a good five days working off and on, and it still is not right. In end I decided to mount the engine upright, and use metal mounting plates (my now standard method of mounting engines) to allow easy changes of engine, The proposed engine is a .36, but it will now be possible to install a .40 with only minor trimming of the cowl. This model would make a wonderful Class One carrier model if I can get it all to work; no winner, but well within the spirit if the game.

Biggest problem is the muffler and where it sits, any change to the original inverted design is a source of problems and extra work. After trying out a few theories I just went with the standard silencer and cutting a hole in the fuselage side and the cowl. That's' when the troubles began, but more of that next time.

The fin has been a simple cut and glue in some rudder offset, and the ailerons fixed in place by changing the hinges to thin dowel and glueing in place

The arrestor hook could be a brain teaser, as unlike a profile fuselage, the hook will be in-line with the tail wheel. Need to to do a lot of pondering on that one, as I have managed to work out the further back from the CG the hook pivot is the less  downward force on the U/C there is?

I already know what bellcrank arrangement I will use so that is sorted, as was buying a set of bench mounted metal shears. For most of my modelling life I have been fed up with cutting sheet metal with inadequate tools. This is a bit of overkill, but should make the production of custom sizes of bell cranks, metal tanks, and associated ironmongery, a lot easier.

The biggy is fitting an undercarriage. It means cutting into the wing underside covering and reenforcing whatever I find and fitting mounting plates.

Flying site

My club now FINALLY! has the new second circle sorted and the correct size, so not only do helpers have a chance to retreat somewhere from from the flight path, but the carried deck, such as it is, can be left out, without interfering with other forms of flying too much, so I can plough things into a deck again. Woopeee! 

Stuff

So as you can see I am still doing stuff, and hope for a bit more success and less wasted time in the future.




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