Tony Patman
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Posts posted by Tony Patman
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Have you tried the Jorvik Centre in York? Lots of vikings there...
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ALLEGEDLY ordinary household paint like Dulux is fuel-proof, but I've never tried it myself. Sorry, can't remember where I read this, but I do remember distinctly someone saying that they had used it successfully.
Indeed your flight box would be a good thing to practice spraying with! Didn't think of that angle...
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I think Byte realised he had downrating switched on, switched it off, tried a flick roll and crashed. Oops. Does this mean, Byte, that you thought up until then that the response was sluggish because of the deactivated ailerons, but in fact it was due to the downrating, and when you switched that off the improvement in agility took you so by surprise that you lost it? The implication being that deactivating the ailerons on the upper wings did not make that much difference after all.
Anyway I hope you get it all repaired, including the push-rods.
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I crashed on Sunday, so count me in too.
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It's made of wood: says so here. Actually that page very usefully gives pretty much all the information you need to build one without the expense of buying the actual kit...one for my archive, I think
Is it worth faffing about with compressors just for a flight box? I suppose if you have a snazzy design in mind; but otherwise I'd just grab a brush and slap on some Dulux, in which case you should start by applying primer to the bare wood, then apply undercoat then liquid gloss paint, or skip the undercoat and use one-coat or exterior gloss, or satin finish paint. Exterior will really keep the rain off, since you might find that satin suffers after some wet flying-field exposure.
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In David Boddington's book there is a diagram of a hidden aileron mechanism which I think is different from Eric's suggestion as I don't think it involves sliders. A hinge is fixed in the leading edge of the aileron at an angle off the plane of the aileron. A rod is attached to the other flap of the hinge, which protrudes inside the wing. As the rod is moved side-to-side, the aileron, by virtue of the angle at which the hinge is fixed, pivots up and down. The rod can therefore be actuated by a push-rod at right angles to it down the wing, either from a central servo or from a dedicated one closer to save a long rod run. I suppose you'd use a ball-link to connect them, as I think the rod attached to the hinge would need to pivot relative to the main push-rod. Anyway, the mechanism shouldn't be any fatter than the aileron itself, and can be concealed entirely within the wing without the need for any horns or push-rods protruding outside.
It was a challenge to figure out the spacial transformations involved. After a period of waving my hands around in strange configurations, I kind-of succeeded in visualising the motion, but I have a vague intention to build a mock-up at some point just to see how it works before trying it in a model. If anyone beats me to this, or has an implementation already, I'd be interested to see some pictures.
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Update: the model is fully assembled, and too tail-heavy, even with 5oz of ballast at the front. Hmm. I could try a lighter aluminium tail boom; or a plastic one (a bit bendy and difficult to get straight)...any other ideas? Don't really want to add another 8oz of ballast...
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"took the whole top off my left forefinger knuckle"
Bloody hell, Peter! -
Actually I've already got a Tutor 40, but I wanted to build something myself. I got that book and, well, it's quite good at holding one's hand through the building process, so I thought it would be ok.
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See this thread for the origin of the model.
The model is a pod-and-boom design, so the engine is at the back, as a pusher, and the battery is shoved right up into the nose along with the present 5oz of lead. The design suggests that 4-6oz of weight should be enough to place the CoG correctly. The pod is mainly ply, and the wings and tail are almost entirely balsa. The boom is an aluminium tube, and was difficult to source at all, so I suspect that it is of a thicker wall than the one used in the prototype. Hmm. I suppose I could remove the tube and see if I can find someone to bore it out a little. Any ideas? -
Yes, I got it going ok, and it's now firmly bolted to the model. Sadly the model has come out rear-heavy, and would seem to need at least another 6oz in the front to move the CoG to the right place. This seems an awful lot.
Steve, it sounds like your experience matches mine quite closely, including the stain on the patio... -
The challenge is being able to judge the tolerances and know where and how much to adjust the wing seating, for example. Therefore my question was about how fastidious I need to be. From your very helpful answers (thanks), the answer seems to be "as precise as you can be bothered, but don't worry too much if it isn't perfect."
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"Behold, Camelot!"
"It's only a model."
"Shh!" -
How important is it to get the alignment of the wings, tail and fin exactly right? I guess any anomaly will introduce some sort of bias, resulting in a tendency of the model to bank, but isn't compensating for this what trim is for? I guess that the more accurate the alignment, the less trim will be needed, right? But what degree of tolerance in alignment would be practical? 1mm too high or low at the wing-tips? 5mm?
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Hi, Andrew. My impression is that the Micro T is quite challenging enough for a beginner. The DH71 is more complex in a number of ways and I think it would be for us to try to run before we can walk.
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Thanks, chaps. I've got some options now! I must say, simply glueing something on the end does seem simpler than heating, filing, et c.
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I have two 36" plastic control snakes. I have some fittings to clamp the inner tube at the servo end, but how can I attach a clevis to the other end? Just epoxy it?
BTW, the inner tube is too narrow to screw a wire push-rod into. -
Richard - I am still using the little glow-start, and flipping: I can't afford to buy any more equipment at the moment. However, the engine does start much more readily now that I have worked out how to "stoke it up" adequately. Perhaps it will get even better when I can afford more controllable and powerful starting gear.
I think the main reason for my difficulties has been my lack of experience. -
I went straight for the Micro T. I may live to regret this, but...
It's a curious aircraft and, having almost completed it now, I have to say that the "Bushwhacker" project starting now in RCM&E looks easier and cheaper to build. The Micro T, however, is at a reasonable level for a novice with a bit of existing nous (like wot I think I am). I'm sure my aircraft is far from perfect: the bottom hatch is a bit too big, I've got work to do to make the wing sit straight and balance, and I'm still not sure whether I am supposed to try to introduce some side- and down-thrust when I attach the engine.
The tail boom was a challenge to find. To cut a long story short, I got it from an ebay supplier: http://stores.ebay.co.uk/Ringwood-Precision-Engineering. Make sure you ask for him to select a perfectly straight tube, and to bind it to a piece of wood or something for transit: our first attempt resulted in an aluminium banana which I refused at my door, and this was undoubtedly the carrier's fault.
It would be good if we Micro T builders could use this thread to confer, as it does have its peculiarities and I could have saved myself some time if I had had someone with whom I could discuss before. -
Glad to discover that I'm not the only one, Ian. Have you built any of the models yet? I'm approaching finishing the Micro T (needs installation of radio gear and engine, balancing and covering).
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Alan:
"what method are you using to keep carb barrel in one place?"
I don't think you mean "how are you attaching the carb barrel to the throttle arm?" so, assuming you mean "how are you controlling the throttle?", then it is held by a pushrod attached to a lever fixed to the test stand. The lever bearing is a tight screw squeezing the lever between two washers so that the friction stops the throttle moving unless I move the lever. I should provide a pic of this to show what I mean; but the upshot is that the throttle is firmly controlled.
I understand what you are saying about the main needle setting. The 1 1/4 setting was achieved like this: start up, close the needle to the point of "screaming its head off", then open a few clicks to ensure good lubrication. The engine slows down slightly but, as someone said, losing a few revs is a good price to pay for a well-lubricated mechanism. On reflection, I think my engine stopped last weekend because I was trying to find the lowest possible throttle for idle, and closed it too much :)
Am I right in my understanding of the relationship between the idle and main needles? The main needle valve is the source of the mixture for most of the travel of the carb. barrel, but, as you close the throttle, there is a point where the main valve is cut out and the idle valve is cut in (presumably with a slight overlap so that there is no break of fuel supply). If either needle is too lean or too rich, the engine is likely to stop when this point is crossed toward the incorrectly-set mixture.
Going back to the throttle control, this raises a point about finding and using the idle. Clearly there is a physical position of the throttle arm/carb. barrel which is the minimum at which the engine will continue to run, assuming that the idle needle has been correctly set. In flight, you'd want this position to be at the bottom of the throttle stick travel, wouldn't you, so that the engine couldn't be stalled accidentally and the cut-off switch needed to be used to stop it deliberately on landing? My reference book doesn't mention such a set-up, so do people not bother and just try not to close their throttle stick too much, or is this achieved by cunning push-rod length judgement, or by trimming the throttle throw on the TR?
What jolly fun this all is. I should have got into it years ago. -
I got the book from Amazon, I think.
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Here's a reply, Garry! I want to build this too, as it looks like a good model to introduce me to leccy flight, but I left the magazine on the bl**dy train...
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Alan, yes, dammit, you've rumbled me: I am, in fact, a large aspidistra.
No, I'm not a plant! I'm not sure whether you mean "he actually knows what he's doing and is faking ignorance" or "he's ignorant and out of his depth"! I just read books and things, and fiddle about down in my cellar. I really am a beginner: I can't even fly yet. A few circuits a few times is the most I've done: getting up so early on Sunday mornings is so hard...
Certainly I've put much more time into building over the winter; but I always suspected it'd be like that with me. Probably I just haven't been out flying nearly enough yet. When I can go solo, then I can go to the field whenever I want, and now the summer is here I hope I can focus on achieving that. -
Steve Hargreaves said: "The idle needle is usually factory set & shouldn't need more than a 1/4 turn either way to finalise it...you didn't touch it did you? You did??!! Ah!!!"
*sigh* I'm sorry, I'm a fiddler. Anything mechanical, I have to twiddle everything. Anyway, I did pretty much what you described to reset the idle needle and hopefully managed not to damage the carb when I had to tighten the nut. In doing so I worked out what the screw on the side was for :)
Yes, it definitely was the rocker cover. Yes, I did have the glow start removed (I'm just cooking with gas now).
I'd heard the thing about always running slightly rich before: I assume this is to do with there being enough lubricant getting through. BTW, I do put after-run oil in too.
In the name of the fuel pump, the glow and the holy needle valve, Amen.
Looking for a Viking
in All Things Model Flying
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