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That is ridiculous! Quite impressed with its speed and maneuverability, you must have some good eyes to keep track of it buzzing around. The crash in the first take made me cringe, but no mass=no damage. The tweezers holder on the TX is a nice touch. Really nice work as always.
Nick |
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My [failed] attempts to date with really small stuff rely on lots of incidence and thrust so with the power off they plummet rather than glide! Rob |
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RobT on right thrust - Sorry, should have been more explicit. It's 6 degrees right thrust, 6 degrees downthrust and 6 degrees right vertical stab angle. I established these amounts on my 4.4" Spitfire, and they have worked well on the 4.6" P-51 and on Bipe-50. The vertical stab is attached to the fuselage only as far as half way back from the LE, and there is a vertical crease line at the half way point. The rear half of the vert stab carries the actuator and rudder. This lets me bend the vertical stab to adjust the right trim by relatively large amounts. The throws on the rudder are extremely small, nowhere near enough to use for trim.
Airlight on the Rx - Yes, I make my own receivers. I developed the Rabbit Rx back around 2007. It uses the 900 MHz band and frequency hopping technology, (hence the name - Rabbit, hopping ... never mind). A "normal" one weighs 115mg though I have made many variations. There's an old thread at https://www.rcgroups.com/forums/showthread.php?t=754973 Nick Liechty makes them now and you can buy them from him at http://microflierradio.com/Receivers900.html Martin |
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Good name choice Martin, Thumbkin would be a lot of fun to have on my desk at work. I have seen the Rabbit Rx before (I didn't realise you were the creator), but way out of my price range for now I'm afraid. Thank god they come with wires attached though, my soldering would destroy one of these in a heartbeat
Not quite the point I know, but is there any likelihood of plans for this, to make a bigger one? I've got a lot of quite thin eps sheet that weighs almost nothing, I think I could get a pretty light airframe if it was even 8-10" wingspan. |
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There is a more moderately priced alternative in the DelTang Rx46 and it can be used with a proper transmitter:
http://www.deltang.co.uk/rx46.htm |
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Nice work Martin.
Reminds me of the Amethyst Falcon. Cheers Dave |
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Martin,
How long is 'Thumbkin' and do you have a rule-of-thumb (pun intended) for horizontal stab size versus main wing size ? From your photos the horizontal stab looks about half of the main span and about the same chord, is this by design, experience or just looks right ? I find this really small stuff fascinating. Thank you Rob |
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Anyway, not to detract from Martin's great achievement, I will just say thanks for sharing, I wish I could make my own look this good, this small. |
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Airlight on plans - I have attached a pdf of the plans
Dave - I had never seen the Amethyst Falcon , but you're right, it does look similar. RobT on rule of thumb for size of horizontal stab - Smaller planes need proportionally bigger hstab and vstab areas, around 50% more than true scale. I have never heard a good layman's explanation for why this is. If anyone has an explanation I would like to hear it. The relationships I developed for my own use some time back are: Dh * Ah = 1/4 * Aw^1.5where Aw = total wing areaI know, I should be talking about the center of lift etc, but I don't know where that is. For Thumbkin: Dh * Ah = 0.234 * Aw^1.5 |
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Martin,
Thank you for the maths, I can see why your stuff always works so well. I am familar with the classic centre of lift / centre of gravity 'balance' diagram but it is very useful to see your practical numbers especially for the very small stuff. Do you know if this still works well for nearly square wings (span = chord) ? Thank you for sharing your hard work, Rob |
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Colourful Thumbkin...
Martin, I hope you won't mind these. I'm quite taken with little Thumbkin, and have started my first go at building an 8" WS version. I did some liveries, and got a bit carried away. If you'd rather they were'nt on here, let me know, I'll delete them.
All should have your moniker on them, as far as I'm concerned I just did some colouring in. Anyone wanting to play with them, I just use a program called Paint.NET for my graphics, it's really easy to use, so you could get these and recolour/shrink/expand them, and break up the image for printing at your prefered scale. Hope you'll enjoy |
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Last edited by Airlight; Sep 10, 2014 at 06:50 AM.
Reason: Just a couple more..
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