Need to Replace a Kyosho 240S Motor with a similar motor

PaulF · Jan 31, 2002, 12:23 PM

Hi-

I am currently using a Kyosho 240S Motor in my T48 (straight-winged T52 with ailerons), along with:
3:1 gearbox
10 X 7 (25.5 X 17.75 mm) Master Airscrew glass-filled prop
8 X CP1700 cells

Once I complete my ElectriCub, I’ll move everything over to it and (gasp), retire the T52.

I had ordered a Magnetic Mayhem back in December, but since they are on backorder, I borrowed the Kyosho 240S from a friend. The motor was designed to be used in an R/C buggy, with 7 X 1200 mah cells and have a 4-minute running time, which equates to a constant 18 amp current draw. To my surprise, this motor works out really well, but since I borrowed it, I need to get something else. The Magnetic Mayhem or Atomic Force look like the best alternatives and I’ve the MM on backorder, but unsure when it’ll arrive. Any recommendations on a comparable replacement? Do I go Speed 500 or Speed 600? Since I am still dorking landings, I’d like to stay away from a blushless system.

Here are the specs for the 240S from MotoCalc:

Adjustable timing; advanced ~ 2 degrees
Bearings on both ends
Constant: 2900 rpm / V (estimated)
Idle current: 2.5 A (estimated, although I register ~ 1.9 amps)
Resistance: 0.04 (estimated)
Weight: 6.4 ounces (181 grams)
50ft (15m) above sea level
45F (7C)

Read out from MotoCalc at full throttle:
Batt Amps: 22.4
Thrust: 28.7 oz (821 g)
Rate of climb: 866 ft /min (4.45 m/s)
Full throttle run time: 4:33 minutes
Motor Temperature: 129F (54C)
Motor Efficiency: 78.6%

Partial throttle run time (assume 250 ft/min climb or 70% throttle): 11:03 minutes
Thrust at this throttle setting: 15.4 ounces
Motor Temperature: 87F (31C)
Motor Efficiency: 73.9%

While MotoCalc is typically liberal with battery consumption, I do typically enjoy 11-12 minute run times and the motor is cool to the touch.

What’s available that’s similar? Anyone have any experience with Graupner Speed 500s?

Cheers,

Andrew Mifsud · Jan 31, 2002, 02:43 PM

Yup. I've lost my Motocalc due to a hardware problem but from memory and experience, the Speed 500 Race7.2V,(Part 1739?) is very close to what you're after and has a max efficiency of 76% at 14A. It doesn't like more than 25A and at 28A will only last about 5-10 flights. Guess how I know? It is a good inexpensive motor.

The other close match that's a little more expensive but is very good is the Speed 600 BB SP either 7.2V or 8.4V. The 7.2V is a bit hotter, the 8.4V is a bit cooler but has replaceable brushes.

Andrew

PaulF · Jan 31, 2002, 04:49 PM

Andrew-

I just ran the numbers on the Speed 500 Race7.2V (1789) and it looks great. Crusing time is actually tick better than 240S, assuming 250 ft /min, providing a 11:20 run time as opposed to the 240S' 11:03.

Full throttle climb is not as good, but I can live with it- 681 ft /min compared to 886 ft / min.

SInce full throttle for the 1789 equates to ~ 20 amps, what type of longevity do you think it'll get?

Graupner also has a BB version of this motor that beats the 240S (and 1789) on all accounts but it's > 5X the price of the 1789. Are you familiar with it?

Andrew Mifsud · Feb 01, 2002, 06:08 AM

Yes. There's a few variations such as the VS and the RX but they're silly money.
Almost the same as the 500 Race is the 600 BB SP 7.2V. I don't have the part number but with a 4:1 gear, 12*10 prop and 10 cell it would take my Protech Unlimited up at about 1500 ft/min.
None of these carbon brush motors should be run at more than 25A.
I had a Speed 500 Race 1789 in my Aerojet with a 3.5:1 and 11*8 APC and 9 cell for a long time with no problems. Max draw was about 22A. If it's cooled, it's fine at those levels.
The same armature is now living in a BB Tower Hobbies can on 10 cells and 11*9 APC. Max is now about 25A and it's still OK but it has good cooling and doesn't run at max much; only on stall turns, loops etc.

Andrew

PaulF · Feb 01, 2002, 06:52 AM

Andrew-

Thanks for the insight. I have settled on the Speed 500 and will order two of them today. I was going to go with a 3:1 and 10 X 7, but the will now run it the same as you, with a 3.5:1 and 11 X 8. Thrust and time are excellent with this combination.

Jan 31, 2002, 12:23 PM	#1
PaulF Registered User Join Date: Aug 2001 Location: Twin Cities, MN Posts: 371	Need to Replace a Kyosho 240S Motor with a similar motor Hi- I am currently using a Kyosho 240S Motor in my T48 (straight-winged T52 with ailerons), along with: 3:1 gearbox 10 X 7 (25.5 X 17.75 mm) Master Airscrew glass-filled prop 8 X CP1700 cells Once I complete my ElectriCub, I’ll move everything over to it and (gasp), retire the T52. I had ordered a Magnetic Mayhem back in December, but since they are on backorder, I borrowed the Kyosho 240S from a friend. The motor was designed to be used in an R/C buggy, with 7 X 1200 mah cells and have a 4-minute running time, which equates to a constant 18 amp current draw. To my surprise, this motor works out really well, but since I borrowed it, I need to get something else. The Magnetic Mayhem or Atomic Force look like the best alternatives and I’ve the MM on backorder, but unsure when it’ll arrive. Any recommendations on a comparable replacement? Do I go Speed 500 or Speed 600? Since I am still dorking landings, I’d like to stay away from a blushless system. Here are the specs for the 240S from MotoCalc: Adjustable timing; advanced ~ 2 degrees Bearings on both ends Constant: 2900 rpm / V (estimated) Idle current: 2.5 A (estimated, although I register ~ 1.9 amps) Resistance: 0.04 (estimated) Weight: 6.4 ounces (181 grams) 50ft (15m) above sea level 45F (7C) Read out from MotoCalc at full throttle: Batt Amps: 22.4 Thrust: 28.7 oz (821 g) Rate of climb: 866 ft /min (4.45 m/s) Full throttle run time: 4:33 minutes Motor Temperature: 129F (54C) Motor Efficiency: 78.6% Partial throttle run time (assume 250 ft/min climb or 70% throttle): 11:03 minutes Thrust at this throttle setting: 15.4 ounces Motor Temperature: 87F (31C) Motor Efficiency: 73.9% While MotoCalc is typically liberal with battery consumption, I do typically enjoy 11-12 minute run times and the motor is cool to the touch. What’s available that’s similar? Anyone have any experience with Graupner Speed 500s? Cheers,

Jan 31, 2002, 02:43 PM	#2
Andrew Mifsud Registered User Join Date: Jan 2001 Location: Gibraltar Posts: 133	Yup. I've lost my Motocalc due to a hardware problem but from memory and experience, the Speed 500 Race7.2V,(Part 1739?) is very close to what you're after and has a max efficiency of 76% at 14A. It doesn't like more than 25A and at 28A will only last about 5-10 flights. Guess how I know? It is a good inexpensive motor. The other close match that's a little more expensive but is very good is the Speed 600 BB SP either 7.2V or 8.4V. The 7.2V is a bit hotter, the 8.4V is a bit cooler but has replaceable brushes. Andrew Last edited by Andrew Mifsud; Jan 31, 2002 at 02:48 PM.

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Jan 31, 2002, 04:49 PM	#3
PaulF Registered User Join Date: Aug 2001 Location: Twin Cities, MN Posts: 371	Andrew- I just ran the numbers on the Speed 500 Race7.2V (1789) and it looks great. Crusing time is actually tick better than 240S, assuming 250 ft /min, providing a 11:20 run time as opposed to the 240S' 11:03. Full throttle climb is not as good, but I can live with it- 681 ft /min compared to 886 ft / min. SInce full throttle for the 1789 equates to ~ 20 amps, what type of longevity do you think it'll get? Graupner also has a BB version of this motor that beats the 240S (and 1789) on all accounts but it's > 5X the price of the 1789. Are you familiar with it?

Feb 01, 2002, 06:08 AM	#4
Andrew Mifsud Registered User Join Date: Jan 2001 Location: Gibraltar Posts: 133	Yes. There's a few variations such as the VS and the RX but they're silly money. Almost the same as the 500 Race is the 600 BB SP 7.2V. I don't have the part number but with a 4:1 gear, 1210 prop and 10 cell it would take my Protech Unlimited up at about 1500 ft/min. None of these carbon brush motors should be run at more than 25A. I had a Speed 500 Race 1789 in my Aerojet with a 3.5:1 and 118 APC and 9 cell for a long time with no problems. Max draw was about 22A. If it's cooled, it's fine at those levels. The same armature is now living in a BB Tower Hobbies can on 10 cells and 11*9 APC. Max is now about 25A and it's still OK but it has good cooling and doesn't run at max much; only on stall turns, loops etc. Andrew

Feb 01, 2002, 06:52 AM	#5
PaulF Registered User Join Date: Aug 2001 Location: Twin Cities, MN Posts: 371	Andrew- Thanks for the insight. I have settled on the Speed 500 and will order two of them today. I was going to go with a 3:1 and 10 X 7, but the will now run it the same as you, with a 3.5:1 and 11 X 8. Thrust and time are excellent with this combination.