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Balsa Shavings
02-01-2006, 05:50 PM
This is my latest creation. I call it Version 1.0. I'm in need of some technical advice. This is my first electric powered airplane. I want to know if a brushed 7.2 Volt 480 with a 3:1 Gearbox will Fly It. Here are the specs.
Barebones weight with 480 & Gearbox (16 ounces)
Propeller APC 10 X 5E
Wingspan (Flat Bottom) (47")
I also need some feedback on what battery & speed control to use.
Thanks: Johnny

For some reason my picture won't upload. It's a basic highwing Airplane.

flyranger
02-01-2006, 09:55 PM
7.2v means six cells nimh or nicad. You might be able to go to seven, but what is more important is being able to use the weight to balance the plane properly. 3:1 ratio sounds at little too fast for that motor at that prop. A higher ratio like 4:1 would probably be better. Yes, your plane will fly, but will be very underpowered. Don't forget, you also have to add the batt weight, 6 oz or so, making your plane 22 oz at takeoff? May need to consider LiPo 2 cell, about 1000ma or so. Probably a 10 amp esc minimum. Need to consult the motor specs to see what current draw it is maxed out at?

meatball
02-02-2006, 01:06 AM
current draw max for most 480 motors is 25 amps MAX at 7.2V. Like said, your gonna wanna go 8.4 volts or LiPo immediately. It will be underpowered, have you considered brushless? Luckily, the Esskay 400XT sale at hobby lobby has been extended (only 20 dollars!!). Going brushless will save you so much frustration, and its alot prettier. The page for the Esskay sale is below (get one! they're also only 1 and a half ounce and much smaller then a 480 size brushed with more power! Dont need a gearbox either, and look much more cosmetically pleasing)

http://www.hobby-lobby.com/bargain-other.htm

For this motor you can use a 9x3.8 or 8x5 and a 10 amp ESC which you can get from a cheap chinese source for 20 bucks in order to save money (works fine, and much cheaper then castle creations) you can get 10 amp continuous 13 amp burst ESC's here

http://home.comcast.net/~truerc/esc/escNmotor.htm

For a battery, you need something that can handle 10 amps continuously, and that is somewhat lightweight, and if you want cheap to compete with the brushed setup, consider an 8C budget pack from www.commonsenserc.com (http://www.commonsenserc.com) either the 1250 which supports 10 amps continuously and weigh's about 3.5 ounces, or the 1650 which supports 13 amps continuously and weigh's about 4.3 ounces, it depends on what weight you want. Those are prices for a PAIR of batteries, they dont come in singles, but at those prices, who cares

http://www.commonsenserc.com/product_info.php?cPath=37_35&products_id=69
http://www.commonsenserc.com/product_info.php?cPath=37_35&products_id=72

With this setup, according your original post you can get the following target weight:

plane: 13 ounces
motor: 1 1/2 ounces
battery: 3.5 or 4.3 ounces
ESC: 7 grams, not even worth counting
servo's: HS-55's, 3 of them are about 1 ounce
Rx: most mini RX's are .5 ounces or less

So, your total weight will be 19.5 or 20.3 ounces depending on battery selection. With the Esskay 400XT and a 9x3.8 or similiar, it will put out around 20 ounces of thrust on a 3-cell LiPo. This setup ends up not being much more expensive then the brushed variant, and is definitely cheaper if you choose all name-brand brushed components, AND this setup will give your plane about a 1:1 thrust to weight ratio, which is good for spirited aerobatic flight, although 3D pilots will want more

Hope I didnt overload your brain, another consideration with this is you have to get a LiPO charger if you dont have one already, and there's the safety precautions needed for LiPo. However, with a charger, I see no reason to used brushed when the brushless upgrade is so cheap (with Esskay 30 bucks off right now). Also, if you need a charger, you can get a good one for 50 bucks or less, I recommend the TP-425 for small parkflyer packs. Any questions feel free to ask, I know its a lot of info. Make sure you ask before you set it up so you dont fry anything.

Sky Sharkster
02-02-2006, 01:44 AM
To Balsashavings, I think Meatball may be on to something. I haven't checked the price of comparable brushed/brushless motors lately so I took a quick look at Hobby Lobby prices;
Speed 480 Race= $ 24.90 (they also have a BB model for $ 39.90!)
MP Jet G/B Planetary= $ 29.90
MP Jet G/B Offset BB= $ 19.90
MP Jet Offset Plain Bearing= $ 13.90
So the least expensive brushed motor/G/B combo is $ 38.80
Compare that to the Eskay and an ESC for $ 20-30 ( I haven't tried the low-priced ESCs, I'm using Meatball's quote) and it's pretty even dollar-wise. As far as performance, efficiencyand expected lifespan of the powerplant you'd be way ahead with the brushless. I can recommend the Castle Creations " Thunderbird" 18A ESC's, they're about $ 35.00 and work great.
Well, it's more to consider!
Good Luck!
Ron

AEAJR
02-18-2006, 07:43 PM
This is my latest creation. I call it Version 1.0. I'm in need of some technical advice. This is my first electric powered airplane. I want to know if a brushed 7.2 Volt 480 with a 3:1 Gearbox will Fly It. Here are the specs.
Barebones weight with 480 & Gearbox (16 ounces)
Propeller APC 10 X 5E
Wingspan (Flat Bottom) (47")
I also need some feedback on what battery & speed control to use.
Thanks: Johnny

For some reason my picture won't upload. It's a basic highwing Airplane.


How did you arrive at this combination?

tim hooper
02-18-2006, 10:39 PM
a brushed 7.2 Volt 480 with a 3:1 Gearbox ....


Johnny,

What sort of 480 motor do you have here, as there are two wildly-differing types?

The hotter variety has external brushes, whilst the 480 'long can' variety is an entirely different motor with internal brushes.

If it's the long can type then the quoted 7.2 volts is a purely nominal rating and can be disregarded (especially if a gearbox is used). In my experience you can use up to 12v with these motors as long as the current draw is kept below 15 amps or so to avoid excessive heat build-up. On 10 NiMHs or Nicads I'd stay with that 10x5 prop to draw around 12amp, but with a 3S Li-po pack you could go for an 11x5 to get a similar draw.

If you can keep the total weight below 24oz or so, then you should have a gentle 'floater' on your hands.

Just my opinion..........

tim