Servos for Mikado LOGO R/C Helicopters

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Servos for Mikado LOGO Electric R/C Helicopters

Selecting a good servo to match flying style, budget, and heli can be a source of confusion and stress. Drawing upon my own and others' experience, hopefully this page will be useful.

An electric heli can generally use smaller servos than its glow counterpart. Any specs listed will be for 4.8V. JR makes some of the best servos for LOGO helis. The first user testimonial is below.

SERVO CHART

Servo	Futaba 3102	Hitec HS-85MG	Hitec HS-225BB	JR-DS368	JR-3121	JR DS-3421**	JR DS-811	Futaba 9202	JR 9011	JR -DS9411
Torque	51.3oz.-in.	41.7 oz.-in.	54.2 oz.-in.	53 oz.-in.	46.4 oz.-in.	65 oz.-in.	54 oz.-in.	55.2 oz.-in.	60.6 oz.-in.	82 oz.-in.
Weight	.74 oz.	0.8 oz.	.95 oz.	0.8 oz.	0.84oz.	1.04 oz	1.44 oz	1.76 oz	1.31 oz.	1.36 oz
Speed	0.25 sec/60	0.16 sec/60	.14 sec/60	0.21 sec/60	0.22 sec/60	0.18 sec/60	0.18 sec/60	0.26 sec/60	0.21 sec/60	0.15 sec/60
Dimensions (inches-W,L,H)	0.51 x 1.1 x 1.17	0.51 x 1.14 x 1.2	0.66 x 1.27 x 1.22	0.5 x 1.12 x 1.17	0.58 x 1.3 x 1.02	0.58 1.3 x 1.02	0.75 x 1.52 x 1.49	0.79 x 1.59 x 1.4	0.75 x 1.42 x 1.04	0.71 x 1.41 x 1.03
BB?	N	1	1	N	2	2	1	2	2	2
Coreless?	N	N	N	N	Y	Y	N	Y	Y	Y
Digital?	N	N	N	Y	N	Y	Y	N	N	Y
LOGO 10 application	aerobatics	Light Duty	aerobatics	aerobatics	3-D	heavy 3-D	N/A	N/A	N/A	N/A
LOGO 14 application						3-D
LOGO 20/24 application	N/A	N/A	N/A	N/A	N/A	3-D	Good	OK	3-D	Heavy 3-D
Comments	MG, I know that others. including Gary Wright use these, but compare the stats to JR!	Fits into frame with out enlarging servo bay. 1 plastic gear. 3 pole motor.	I would not use this servo because spacers are required to lift the servo away from mian shaft	MG, NO BEARINGS. Perfect fit in LOGO 10 frame. Nice for all but heavy 3D.	Great servo for LOGO 10. Same case as DS-3421	Alloy gear, good for BOTH heli's, best servo for LOGO 10 3D	Good, economical digital servo	Again for me, it's the weight of a Futaba that turns me off	Great coreless servo	The best for a LOGO 20 - I would like to try them...
My experience					Used with my Voyager, then LOGO 10	Currently in my LOGO 10 - very nice!			Currently in my LOGO 20
Approx. US$ Price:	$65 (4)	$30 (4)	$23 (4)	$70 (3)	$70 (2) (3)	$85 (1) (3)	$48 (1) (3)	$55 (4)	$63 (3)	$100 (3)

Sample prices obtained from: (1) = Heliproz; (2) = Rick's; (3) = Horizon; (4) = Servo City

NOTES

**
There is a new nylon geared version of the JR 3421 named the 3421SA. Although I would have preferred nylon gears with mine, I'm OK with metal gears, especially since I already bought spares. NEW! Based on the comments and survey results in a discussion in the LOGOmaniac Forums, I think it's safe to say that only the metal geared version should be used!

Based on comments from several others, I am changing the HS85BB servo to the HS85MG because of the tougher metal gears, even though I prefer nylon gears.

Regarding the requirements for servo size for the LOGO 10:

Some micro/mini servos are deeper than others, and this is a factor in determining suitabilty for the LOGO 10. The maximum depth below the mounting surface that a servo can have is ABOUT 18.5 mm before it interferes with the main shaft and requires spacers. The Hitec HS225BB is one that is too deep to use without the use of spacers and I feel that adding more imperfection to the CCPM geometry is not a good idea. Recently I was investigating one of the Volz servos to use in the LOGO 10, but gave on that idea for the same reason. The preferred 120 degree CCPM setup works best with servos that are 0.5" wide. Wider servos, such as the JR DS3421 that I now use will work fine if one positions the servos so that the aileron servo pushrods are off vertical by the same amount as the elevatar pushrod (as seen from the side view), whether like "/ \" (which I use), or "/ /" , or "\ \".

TESTIMONIALS

Dana set out to do a comparison when he upgraded his servos, so I asked him to write the first user testimonial.....
A 'hands on' short story about JR368 and JR3421 Servos.
I have about 200 flights on my Logo 10 now, probably more. I dearly love the way the machine handles, and it has been trouble free all the way with the JR368 Servos. To put this dissertation in perspective, the Logo and Piccolo are the only RC things I've ever flown, so I know nothing about who or what is the best in the servo game. I just know how the machine behaves in actual experience.

Somewhere well past flight 100, I asked Glen about servo upgrades for heavier 3D, even tho the 368's were still like new in their operation. He instantly recommended the 3421's, which I subsequently purchased and have in the '10 now. So, in this experiment, we have everything the same, including the pilot, except for the servo exchange.

On the Plus Side

The 3421's are noticeably quicker and 'sharper' in control response than the 368's. Not that the 368's are sloppy or soft, but the 3421's make the machine have a more accurate and solid feel around the button at hover and near hover speeds. All this makes the machine handle the gusts and inputs with less overshoot, and you are a better pilot out of the box as a result.

At high speed, high G loadings, the 3421's clearly outperform the 368's. They have more torque available, and operate faster than the 368's. All this tightens up your sequences, and you look better than you did the day before with the 368's.

The 3421's come with a 3 year warranty. Not too shabby.

On the Minus Side

The 3421's are 20% more expensive than the 368's. Actually, they are nearly the same price as the entire Logo 10 kit.

The 3421's are heavier than the 368's. For the three servo's, they add about 20 grams to the machine's lift-off weight. Not a lot, but every gram counts in the Heli game.

Unlike the 368's which drop right in, straight up and down, the 3421's need to be cut into the frame servo landings, and the geometry offset needs to be matched for the three servos.

Summary

The 368's are great servos starting out on your first Logo 10. They are easy to fit on your first build, and it will take a lot of flights before you wish for that extra response speed and torque when you start to spread your 3D wings for real. There is no doubt though, that the 3421's will out corner and out perform the same Logo 10 equipped with the 368's. So in this case, you do get what you pay for!
Dana (Lost Horizon) www.rceheli.com

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**	There is a new nylon geared version of the JR 3421 named the 3421SA. Although I would have preferred nylon gears with mine, I'm OK with metal gears, especially since I already bought spares. NEW! Based on the comments and survey results in a discussion in the LOGOmaniac Forums, I think it's safe to say that only the metal geared version should be used!

	Based on comments from several others, I am changing the HS85BB servo to the HS85MG because of the tougher metal gears, even though I prefer nylon gears.

	Regarding the requirements for servo size for the LOGO 10: Some micro/mini servos are deeper than others, and this is a factor in determining suitabilty for the LOGO 10. The maximum depth below the mounting surface that a servo can have is ABOUT 18.5 mm before it interferes with the main shaft and requires spacers. The Hitec HS225BB is one that is too deep to use without the use of spacers and I feel that adding more imperfection to the CCPM geometry is not a good idea. Recently I was investigating one of the Volz servos to use in the LOGO 10, but gave on that idea for the same reason. The preferred 120 degree CCPM setup works best with servos that are 0.5" wide. Wider servos, such as the JR DS3421 that I now use will work fine if one positions the servos so that the aileron servo pushrods are off vertical by the same amount as the elevatar pushrod (as seen from the side view), whether like "/ \" (which I use), or "/ /" , or "\ \".