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Too many choices--need advice.

Old 02-11-2004, 03:03 AM
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Default Too many choices--need advice.

I've built my Great Planes BLT and now need advice on an ESC and whether to consider motor and gearboxes with ball bearings.

The 280 motor would work fine with a 10A esc, but I'm wondering if I should buy a more robust one that I can use for other planes. A Castle Creations 35A esc weighs about 12 grams more than the 10A one I'd likely buy and I'm wondering if that extra 12 grams will make a big difference. My next electric would likely be a Mini Telemaster with a 400 motor/gearbox or a Wattage Mini Blue Max (370).

I'd buy them all, if funds permitted. I don't want to weigh down the BLT, but I don't want to spend money on two speed controls if I don't have to.

I'm also wondering if going for the ball bearing versions of the motors and gearboxes will make that much difference on the BLT. Any ideas?

And today I get my super saver coupons from tower and see that I can get the whole Electifly system I need (10A esc 280 bushed motor and 4.1:1 bushed gearbox) for even less, but I am not sure I want.

As for the weight of other onboard components, I will likely go for the Berg Stamp 4 & 2 - .3oz servos. Batteries? Likely Nimh to start...but let's not go there now....

Send help, or money! [8D]
Old 02-11-2004, 08:20 AM
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Matt Kirsch
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Default RE: Too many choices--need advice.

A ball bearing gearbox will definitely increase the efficiency of the overall system, but not by much. For a light 280-powered plane, I don't think you'd be able to tell the difference.

The ball bearing 280 has completely different characteristics than the bushing 280, so it's not a drop-in replacement. You'd need a different gear ratio, different prop, and a different battery.

12 grams, or about 1/2 ounce, won't hurt the way the plane flies, as long as this is the ONLY time you make this kind of compromise. 1/2 ounce here, 1/2 ounce there, and suddenly you have a fat pig that flies like crap.
Old 02-11-2004, 08:45 AM
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Default RE: Too many choices--need advice.

Twelve grams is about the same weight as two micro servos. This is a huge difference for a lite
parkflyer. It will change the flying characteristics for sure. You definitely want to go with a ball bearing gearbox. The bushed gearboxes cost you a lot of power, and will draw more amps that is just wasted energy. Not to mention the extra noise and sloppy fit! The ball bearing motors are nice, but not as necessary as a ball bearing gearbox. If I add weight to a model, its with heavier,(higher capacity) batteries. The AAA's they recommend for this plane are available in 700MAH capacity, and I usually add at least one more cell than recommended (7 cells in this case). The 280 motors I fly like the KAN650 cell better than the AAA's or the 5/4AAA's , as the voltage capacity is higher at the same amp draw. I'd go with the lighter ESC and a little heavier battery. It's worth another $30 bucks or so for longer flight times and more power!
Hope this helps.
Good flying,
Bud
P.S.>The tomatoes weigh more than the Bacon or Lettuce!! I'm sorry! I couldn't help myself!
Old 02-11-2004, 11:13 AM
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Default RE: Too many choices--need advice.

Just one comment - if you are going to move up to 370 and 400 motors your best bet for an ESC is the Castle Creations Pixie 20P, the 35 would really be overkill, but the 20P is pretty light (mine's 12g with wires and Gold Connectors) and is what you'll need to cope with the 10-12A your 400 may draw. The advantage of the Pixie (and the Pegasus) over other brands is that they are programmable for LVC so you'll be good to go with LiPoly if need be.

Cheers, Phil
Old 02-12-2004, 02:28 AM
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Default RE: Too many choices--need advice.

Thanks everyone, for the help.

I will definitely get the BB gearbox, if anything, for less noise. As far as the BB 280, Matt, what makes it so different that you can't just drop it in as a replacement for a bushed 280?

I was going for the Castle Creations 35P for two reasons. One, it is on sale where I'd purchase it and secondly, I got the idea from CC's website that anything less might not handle all that a 400 can be. It is nice to know that the Castle Creations 20P will do the job I need it to. Nice bonus that it will handle the LiPo.

Which is a relief and a 9g load off the BLT! That must be at least one slice of tomato, eh A1Rench?
Old 02-12-2004, 09:02 AM
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Default RE: Too many choices--need advice.

The 280BB is a much "hotter" motor than the plain 280. That is to say that it spins much faster on a given voltage, which translates to a much higher, probably destructive, current draw if it's simply dropped in in place of a plain 280.

To keep the Amps from going too high, you need to gear down the propeller more than you would with a plain 280. The end result is that you want the propeller to be spinning at about the same speed in both cases.
Old 02-12-2004, 12:06 PM
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Default RE: Too many choices--need advice.

By all means go with the hotter set-up. My first electric was the BLT after 30 years of gas and glow. My son and I bought the whole kit with esc, bat, & motor as a package. It could barely keep itself in the air. Maybe just had a bad motor, but it was not a good experience for the firtst electric. Now I have been reading and have learned alot in this forum. I really enjoy these electrics now, No mess no hassel, fly anywhere! Finally I have time to perfect my lousey 3-D flying.
Old 02-12-2004, 09:11 PM
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Default RE: Too many choices--need advice.

RTK,

I bought the BLT before I discovered online discussion groups, which is too bad in a way. I don't think I would have bought the BLT in hindsight. I don't know how other park fliers are, but there very little room in the BLT's wing pylon to put anything. But I'll give it a go and make the best of it.

It sure is nice to be able to come here for help though.
Old 02-13-2004, 02:19 AM
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Default RE: Too many choices--need advice.

The BLT was my first jump into electrics too. I think I made some mistake in building it because it kept spinning to the left after about 5 feet of rolling on the ground.

I did manage to get it into the air once but that was very short lived. I was so excited that I was finally flying that I didn't pay attention to a light pole when I made the first turn. *SMACK* kocked everything forward of the wing pylon clean off. I CA'd it back together but it would never launch again.

Here's what it looked like:
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Old 02-13-2004, 02:25 AM
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Default RE: Too many choices--need advice.

Matt,

Great Planes suggests a 280 with a 4.1:1 gearbox & 6 to 7 cell batteries (550mah) or 7 cell 1200mah with a APC 10 x 4.7 prop.

Do you have any idea what gearbox would be a good ratio to go with with the 280 BB? 4.5:1? 5:1? Same or different prop?

Thanks
Old 02-13-2004, 09:06 AM
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Default RE: Too many choices--need advice.

TP,

Great Planes doesn't have a very good track record with power system recommendations. With a wimpy 280 and the large heavy batteries they recommend, the plane will be a fat pig.

Use a lighter battery. A 7-cell, 300 or 350mAh NiMH (2/3AAA cells) is a nice lightweight choice. Even a pack 720, 730, or 750mAh NiMH (full AAA cells) will be lighter than the 550 NiCds they recommend. What I recommend is a 7-cell pack of CBP650 650mAh NiMH (2/3AA) cells from cheapbatterypacks.com. They're inexpensive, light, compact, and will run your 280 for 20+ minutes. They also have the punch necessary to take advantage of that 280BB or a Speed 300 should you decide to upgrade.
Old 02-15-2004, 12:04 AM
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Default RE: Too many choices--need advice.

Matt,

Just wondering if you had the opportunity to read my post from a few days ago regarding the 280BB and your recommendations for a gearbox. Thanks for your help so far.
Old 02-20-2004, 12:03 AM
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Default RE: Too many choices--need advice.

TP,
Matt probably hasn't answered yet because there is no way to know without having one of those motors on hand to test. From what I can tell there are no published specs on the S-280 motor (as with most things resold under the GP name). However, this motor appears to be the same thing as a Kyosho GP28BB (retired) which is made in japan by Sagami. This may also be the same as the Permax 280BB motor by Multiplex. For what it's worth those are slightly educated guesses. I googled this for a few minutes but didn't get any deeper.

With that in mind, you have two choices: 1. Return the S-280BB motor due to lack of documentation on what it is that you paid $20 - $30 for; or 2. keep the motor and just try a couple different gearboxes until something works right for you.

Personally, if the motor was in the same shape as when I bought it, I'd send it back and buy something that has published specs.

Good luck,
chris.
Old 02-20-2004, 03:55 AM
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Default RE: Too many choices--need advice.

I suppose I can forgive Matt for not being psychic.

I haven't ordered the motor/gearbox yet, so there's no motor/gearbox to return. My servos are on the way and I got my Berg Stamp 4 today though--damn that thing is small. In spite of knowing its dimensions, it still took me by surprise.

I'll do a bit of experimenting with the motor/gearbox and will eventually let everyone knows how it all works. That first flight gets closer everyday!
Old 02-20-2004, 07:45 AM
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Default RE: Too many choices--need advice.

280BB, right? It should be the same as Graupner's, so it's pretty similar in characteristics to a Speed 300, IIRC. Any gearbox/prop setup for a 370, Speed 300, or a GWS EPS300C should yield similar results with the 280BB.

You want a high gear ratio, 5:1 or better, and a 9x7 or 10x8 prop, I think. Check out http://www.gws.com.tw's tables.
Old 02-20-2004, 06:59 PM
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Default RE: Too many choices--need advice.

Thanks Matt.

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