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Old Sep 15, 2001, 12:58 PM
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Gear/prop combo for speed 480 BB Race motor

I have used speed 400motors with sucsess for awhile.
But I have 3 Speed 480 BB Race motors lying around.

Have tried the 480 BB race motor on my flying wing, and it is just awsome how fast this goes.
But I would like to try some gearbox/prop cause:

-Less noise
-More efficient prop
-more efficient motor.

I do not want to have a big prop. But I would like a really big pitch.
Max prop size has to be 5.5" or 6" as an absolute maks.
My question is what gear-ratio to use and how high pitch I can go for?

And are there such things as a prop with 5.5 in diam. and maybe 10" in pitch.?

The speed 480 BB race motor turns an 5"x5" prop at around 20000RPM. With a 2:1 gear this is the same as 5"X10"?
I suspect the prop is not very efficient when one comes over 15000RPM. And a higher pitch at a lower RPM will get the system really moving, and without hurting my ears when I take a flyby

And suggestions and help would be really appriciated.
Cheers
Kjelli


PS. I use 8 cells packs (CP1300 Cells). Have different speedcontollers. But have used 24 Amps controller on the 480 BB race motors when in direct drive.
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Old Sep 16, 2001, 01:02 PM
AMA 697691
Rochester, NY, USA
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Hi Kjelli,

I will be experimenting with a geared 480BB Race system too. I am currently testing a system with a regular 7.2v Speed 480 motor.

The gearbox comes with 3 pinions for the following ratios:
  • 1.7:1
  • 2.0:1
  • 2.3:1

I expect the geared Speed 480 system to draw around 10amps using an 8x6.5 prop.

My understanding of the Speed 480BB Race motor is that it is essentially 1.5 times the power of a Speed 480. An impressive power boost in the same footprint.

When I test the 480BB Race, I will limit my current draw to 15amps. Measuring the motors current draw allows you to "play" with gear ratios and prop sizes within the motor's limits to get the best performance from your ship.

Keep us posted!

Welcome to the E-Zone!
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Old Sep 16, 2001, 04:11 PM
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Kjelli, yes, the 480BB is not the most efficient motor around, but I'm not convinced that there is anything to be gained by geaing if you keep the diameter down to what is normal for DD, and it appears that you have the prop about right at 5x5. I found that it works very well at 20 ish amps on a 6x3, but take it down to 5x3 and it does very little except draw 18 amps.

Greg, with respect, the "normal" Speed 480 (#6304) draws very little, if anything, more than a 400 6v (my Twin Jet is drawing 25 amps on 5.5x4.3s with 8 RC2000) - it just appears to draw more amps because it turns the prop a little faster

The BB Race really likes to be up around the 18 to 20 amps area, and I'm sure it is going to take a VERY light load to persuade it to go below 15 amps - the #6304 Speed 480 might just be a better bet in this area.

Good luck to you both, and I look forward to reading the results.

Regards, John
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Old Sep 16, 2001, 08:31 PM
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Stavanger, Norway
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Hei psan.

Keeping the prop diameter down will not do much in regard of higher system efficieny - which is the whole point of gearing.

If you're worried about prop strike while landing with a larger diameter prop you should look at some folders.

As for GB ratio's I'd think the 480BB Race will need somewhere around 3,7-4,4:1 gearing and a 9-10 inch diam. prop with a pitch to suit ampwise. Cosmotech have some nice planetary units but they are a little pricey.

Oh yeah - welcome to the 'Zone
-Haldor
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Old Sep 17, 2001, 07:48 AM
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follow up

Here are some thoughts I have. please correct me if Im wrong. (as I sure am )

- Bigger prop = More efficient
- Lower RPM = More efficient prop
- higher pitch on prop = load on motor.

The speed 480 BB race motor is to be used in pusher mode.
To reverse the motor with traditional methods is WRONG, as the motor is timed for pull mode.

A gearbox which reverses the spinning direction will make the motor go the "right" way, while the shaft from the gearbox will go the wrong way, which again is the right way if I want to use this in a pusher mode? So this pulls the efficiency of the system up.

I get the motor go go the "correct" way that it is timed for.
And with a same diam. prop but with much higher pitch (at a lower, More efficient RPM for the prop). This will hopefully be a little more efficient than running the motor in DD and the "wrong" way, and at RPMs around 20000.

Is anyone still following me?

The point of my gearing this motor is to reverse the direction of the motor. And get the RPM around 10000.
I have this idea that a prop is much more efficient at 10000 RPM than 20000RPM. Without going up in prop size, but only going up in pitch.

Not to mention to get rid of the propeller noise one gets at 20000RPM.

Hope anyone can comment me on my thoughts. Am I totally off target here?

Cheers
Kjelli
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Old Sep 17, 2001, 09:49 AM
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Kjelli,

Welcome to the world of many alternatives.

This thread topic normally belongs in the "Modeling Science" forum but i'll leave it here for personal interest. We'll call it a moderators "discretion".

As you can see, there are many different thoughts on what is the "right" way to configure a system. You will find that an important part of the equation is based on the ship design and how you like to fly it.

On your geared example, you can use a larger prop which will give you more thrust. Since the prop will spin at 10000 RPMs, you'll likely have plenty of speed. The pitch limitation will be set by you maximum current draw for the motor.

For me, I am new to the Speed 480 and 480BB Race motors so I am looking to others for experience on proper current draw for reasonable longevity.

I had a chance to "fire up" my system last night and it ran several seconds before the pinion gear started slipping. I was using a Speed 480, geared 1.7:1, 8x6.5 prop and it was drawing 15amps before the pinion gear started slipping.

According to John, the Speed 480 is happy at 15amps and the 480BB Race is happy at 20amps. This would mean that my original estimate was low by 5amps for each motor. I consider this good news.

Does the 480BB Race need to be re-timed when used in a gearbox that requires the direction to be reversed?

Haldor gives us a suggested setup using the 480BB Race with a 4:1 gearbox and 9x10 prop. This looks like a possibility for my upgrade on my stock Speed 480 configuration listed above. My application is the new Wattage Extra 330L. I will likely want a 9" prop and plenty of top end speed.

Thanks for all the information guys! The E-Zone is a great place for sharing experiences and proven configurations.

Regards.
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Old Sep 18, 2001, 02:56 AM
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Greg, we have done quite a bit with these motors in a Pico Jet (lots of cooling), and the BB Race lasted a season of regular use at 20ish amps (static) before the brushes gave out, the rest of the motor is fine.

On the #6304 S480, I don't know how the windings will survive above the 12ish amps that we are using them at, but that represents a 5.5x4.3 on 8 cells giving 15 600 revs (over 16k at peak), and the windings are not that thin.

BTW, of course the Speed 480s have fixed forward timing - except the BB Race which is adjustable timing, and there is a reverse timed Speed 480 (#6304L) available.

Good luck with your tests,

John
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Old Sep 18, 2001, 08:07 AM
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Quote:
Originally posted by Greg Covey
Does the 480BB Race need to be re-timed when used in a gearbox that requires the direction to be reversed?

Haldor gives us a suggested setup using the 480BB Race with a 4:1 gearbox and 9x10 prop. This looks like a possibility for my upgrade on my stock Speed 480 configuration listed above. My application is the new Wattage Extra 330L. I will likely want a 9" prop and plenty of top end speed.
I assume the s480BB Race needs to be retimed if reversed as the "Race" designates advanced timing.

BTW - the example I suggested is not 9x10 prop but 9-10ish inch diamter prop with a pitch to suit your desired amperage. Just so there is no confusion

-Haldor
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Old Sep 18, 2001, 08:14 AM
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Re: follow up

[QUOTE]Originally posted by Kjelli
[B]
- Bigger prop = More efficient
- Lower RPM = More efficient prop
- higher pitch on prop = load on motor.
</quote></b>

True.

<b><quote>
The speed 480 BB race motor is to be used in pusher mode.
To reverse the motor with traditional methods is WRONG, as the motor is timed for pull mode.

A gearbox which reverses the spinning direction will make the motor go the "right" way, while the shaft from the gearbox will go the wrong way, which again is the right way if I want to use this in a pusher mode? So this pulls the efficiency of the system up.

I get the motor go go the "correct" way that it is timed for.
And with a same diam. prop but with much higher pitch (at a lower, More efficient RPM for the prop). This will hopefully be a little more efficient than running the motor in DD and the "wrong" way, and at RPMs around 20000.

Is anyone still following me?
</quote></b>

Yeah. Your s480BB Race is currently running as a pusher DD and in the wrong direction relative to the timing. You'll need an off-set GB to get the motor running the right way while spin the prop the right way in pusher config.
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Old Sep 18, 2001, 11:15 AM
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John and Haldor,

Thanks for the valuable information. Yes, I did mis-read your prop range for a size.

My stock setup is an unknown Speed 480 motor using a gearbox that requires the motor direction to run in reverse. This concerns me a bit since my previous assumtion was that a canned Speed 480 was neutrally timed. The stock setup comes this way from the manufacturer so it may be ok.

My setup draws 15amps on 8-cells of 800AR using a 1.7:1 gear ratio on a 8x6.5 nylon prop. The RPMs was 8200.

After John's last post, it sounds like this may be a bit hot. I do have an alternative of two other gear ratios that should reduce the current; 2.0:1 and 2.3:1 This particular gearbox comes with 3 pinion gears.

Your opinions are appreciated. Thanks.
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Old Sep 18, 2001, 01:17 PM
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To clarify the point I hope people do not mind me repeating:

The Speed 480BB Race has ADJUSTABLE timing, and it is a simple matter of slackening two screws to adjust the timing whether forward or reverse.

ALL the other Speed 480 motors (whether designated Race or not) have FIXED ADVANCED timing, but the 6304 is available in both forward and reverse (6304L) models, just like the Magnetic Mayhem - in fact, they look just like a younger brother - or sister.

BTW, my 6304Ls are marked "Sagami" "Japan"

Greg, I really can't say whether the BB Race is too hot or not for the geared application, but from having used a 400 6v, the BB Race, and the comparatively mild 6304 Speed 480 direct in the same model I really have a preference for the relative efficiency of the 6304 - that must have been coming through quite strongly in my posts of late

The only one of the bunch that I have no experience with is the 6330 Speed 480 Race, but that is very nearly as hot as the BB Race:
http://www.hobby-lobby.com/speed280.htm

Best regards, John
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Old Sep 18, 2001, 03:06 PM
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Thanks, John.

If it wasn't for your reiteration of things, I would be very confused indeed.

I had two test flights at lunchtime today using the Speed 480, 1.7:1 gearbox and 8x6.5 prop on 8-cells of 800AR. The current draw was a hot 15amps.

The power during the flight I would rate between fair and ok. This means that my Speed 480BB Race will be subtituded soon in an effort to boost power.

I will re-time it for reverse direction and limit the current draw to 20-22amps.

I do not see the 6304L motor at Hobby Lobby, hince my ignorance of its existance and timing for one direction.

We'll see what this 480BB Race will do now.
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Old Sep 19, 2001, 02:59 AM
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Sorry Greg,

I should have said that the 6304L is relatively new and available from www.hoellein.com and is also the motor in the Star Jet Competition drive set (motors, props, etc). A friend is getting some very good flights on 8x800AR with his Pico Jet (as I do with my Twin Jet on 8xRC2000). I do like this motor - though I haven't tried a Permax 450T.

Perhaps Hobby Lobby might add the 6304L to their stock list?

Good luck, John
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Old Sep 19, 2001, 07:11 AM
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ok

Im am going to do an experiment as soon as I have the time.

Experiment 1 :

Reverse the timing on the speed 480BB race motor, and compare rpm, amps, thrust and flight time Vs "un timed" mode.
(I need some help here to get the timing correct)


Experiment 2:

Install a gearbox to get the RPM down and use same diam. on prop. I will adjust the load with going up in pitch.
And compare amps, thrust and flight time against the DD case (timed and untimed).

This will show how much more efficient a system with low RPM is against a system with high rpm. In short it will show prop. efficiency.

Is there some graphs on the net that shown curves with the relationship between efficiency and timing.?
Or something simmilar, amps vs "degrees timing" etc. anyone know anything about this?

I have read some articles about timing etc. But they are too simplified, and just tells you what to do with that particular motor. I have not seen a good explanation about timing and the effect is has on the motor. (like RPM, amps, wear ++++).
Im interested in knowing more about how to propely time all motors, since they are all the same type of motors.
I reckon the graphs with efficience and timing all look the same shape in general.?

Any thoughts are appriciated.

Cheers
Kjelli
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Old Sep 19, 2001, 09:18 AM
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John,

Thanks for the 6304L source.

I got stopped "dead in my tracks" last night when trying to replace the Speed 480 motor with my 480BB Race motor. The shaft sizes are different.

The Speed 480 motor has a Speed 400 shaft size and the 480BB has a Speed 600 shaft size. I'll be visiting my LHS today at lunchtime because I saw a Great Planes GD-600 gearbox there on my last visit.

My Speed 480 motor was completely unmarked. I do not know which direction it is timed for. Could the manufacturor have made a design mistake? I also don't know if a 15amp draw was a reasonable value using the 1.7:1 gearbox and 8x6.5 prop.

Once I obtain my new gearbox, I must choose between using a 480BB Race motor and a Permax 450 Turbo motor. The GD-600 is a 2.5:1 ratio but can be changed to 3.0:1 or 3.8:1 also. In my application, I want to stick with an 8" or 9" prop for appearance and lean towards speed.

Regards all.

P.S. It appears that Hobby Lobby has them in stock and the part will be listed soon.
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