Subject:
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Re: Aviation Tractor MOC
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Newsgroups:
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lugnet.technic
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Date:
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Mon, 17 Jun 2002 11:36:59 GMT
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Viewed:
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1497 times
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Nice job Simon! I always like watching these machines at the airport too,
did the spec sheets you received state what sort of horsepower and max speed
these things have?
As for the power problem, two 9V gear motors should be able to drive a
machine of that size and weight quite well. Off the top of my head I'd
suggest a gear ratio of around 24:1 from motors to drive axles; it will be
pretty slow, but then the real things are pretty slow anyway. The double
diff is probably superflous, certainly I've been able to gang two motors
together without using a diff beforehand, and as long as the RPMs don't
differ too much I can't see there being any great efficiency losses.
I don't have an 8880 but I remember people mentioning that the CV joints
have a lot friction in them, so perhaps this is causing some problems?
Another thing I've come across, especially with multi motors setups, is the
requirement for the batteries to be delivering enough current. A 9V PP3 just
cannot cut it, but 6 normal AAs in parallel are great. Another combination
I've used recently to surprisingly good effect is 8 AA NiMH rechargables in
parallel using a battery box from Maplin (about 70p). This gives a total of
9.6V and really shifts the motors; motor power goes up as the square of the
voltage, so if you had previously been using 6 NiMH giving 7.2V, going to
9.6V makes a serious difference. Of course the motors are only rated at 9V
so there may be some risk in this... I'd be interested to hear opinions on
this.
I'm not sure if the compressor has a cutoff, as running a motor in a heavily
loaded of stalled state such as when an air tank gets filled up also
consumes a lot of power from the power source.
Jennifer
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Message has 4 Replies:
 | | Re: Aviation Tractor MOC
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| Hi all, (...) This reminds me of a series of vehicles that my friend Robin and I made, oh, 15 or so years ago now. We were building remote-controlled cars, using a bunch of batteries taped together for power, and a car speedometer cable to steer (...) (22 years ago, 17-Jun-02, to lugnet.technic)
| | | Re: Aviation Tractor MOC
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| Yes, nice job. Well done! (...) If you're going for a real power puller, then a ratio of 24:1 sounds good. But beware! You'll be getting into gear-breaking torques. Be sure to use the new style 24t gears, if you should need 24t gears. I agree with (...) (22 years ago, 17-Jun-02, to lugnet.technic)
| | | Re: Aviation Tractor MOC
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| There are two issues here. 1. Can the motors sustain more than 9 volts without damage? If I was TLC designing motors for use by kids, I'd make sure there was a large safety margin. New batteries are typically 0.1 - 0.2 volts above their nominal 1.5 (...) (22 years ago, 17-Jun-02, to lugnet.technic)
| | | Re: Aviation Tractor MOC
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| Thank you for your comments. (...) Engine: Deutz BF 6M1051C - V6 11.906 litres 300kW (400bhp) @2100rpm 1840Nm @1400rpm Performance: Max tractive effort 390kN (88000lbf) Max speed 30kph (18.9mph) Nowhere near as much bhp as I would have guessed (and (...) (22 years ago, 18-Jun-02, to lugnet.technic)
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