KST HS08 F5J Servos Coming

KST is bringing us some new servos for our F5J planes with the HS08. They are nearly as small as the X08, but nearly as as powerful as the X10mini!

Splash

New Servos from KST!!

KST is bringing us some new servos for our F5J planes with the HS08. They are nearly as small as the X08, but nearly as as powerful as the X10mini! These bad boys are going to be a perfect match for most 5J planes. I received some pre-production samples to check out and the 7075 Alloy case looks and feels amazing. These have been running smooth and precise on my bench tests thus far and I am really excited to get them into a wing soon.

The HS08 will come in an A and B version with the difference being the mounting tabs made to accommodate wing or fuselage mounting. The case measures out to 24mm x 8mm x 25.25mm and the weight is 11g. The gears are hardened steel driven by a coreless DC motor. I don't have pricing or availability info yet, but I wanted to get this posted to let you guys know about them as soon as I could. Here's the spec sheet:

  • Rated Voltage: DC3.8V-8.4V
  • Voltage Range: DC6.0V
  • Stalling Torque: [email protected]
  • Rated Torque: [email protected]
  • Stalling Current: 0.68A
  • Rated Current: 0.25A
  • No-load Speed: 360°/S
  • Rated Speed: 250°/S
  • Default Travel Angle: ±60° = 120° total travel
  • Operating Temperature Range: -20°C......+65°C

Look for More Info on the KST Site Here When These Get Posted

Thread Tools
Jun 11, 2020, 09:46 AM
My Quads Better Than Your Quad
racedouge1's Avatar
F5J nothing...I see F3K written all over them.
Jun 11, 2020, 09:58 AM
“Learning Machine”
Sky Angels's Avatar
Way to go KST.

Cool looking asymmetrical case!
Jun 11, 2020, 11:10 AM
Registered User
eitanro's Avatar
Great looking servo.. I'll use it for my next F5J build (whenever that will be...)
Jun 11, 2020, 11:22 AM
Registered User
By the picture I'm guessing not interchangeable mounting holes with current X08?
Jun 11, 2020, 11:48 AM
RCG Admin
Jason Cole's Avatar
Thread OP
I heard they are changing the case slightly on production units to fit the X08Plus frames!!
Jun 12, 2020, 12:31 AM
Camber down and screw it up.
gdouglas's Avatar
Quote:
Originally Posted by racedouge1
F5J nothing...I see F3K written all over them.
F3K nothing. I see F5K written all over them.

Well, not really all over them. It's in really small print, down near the bottom. You have to use a loupe to see it.

--
Greg
Jun 12, 2020, 01:03 AM
ThomasLee's Avatar
These are going to be awesome for F5J models. Right between X08+ and X10 mini.
Jun 12, 2020, 05:54 PM
Registered User
sunnybreeze's Avatar
I like the look of it. So appears they took a 08 and simply enclosed the motor. Really hope the cost is sub $40.00

Like to see a review after they are in a wing and flown!
Jun 12, 2020, 07:23 PM
ThomasLee's Avatar
Quote:
Originally Posted by sunnybreeze
I like the look of it. So appears they took a 08 and simply enclosed the motor. Really hope the cost is sub $40.00

Like to see a review after they are in a wing and flown!
The specs are quite different than the x08 from what I’ve seen in both torque and gear train strength. I doubt it’ll be below $40.
Jun 13, 2020, 06:08 PM
in awe of glide...
Kirkerik's Avatar
Quote:
Originally Posted by Jason Cole
I heard they are changing the case slightly on production units to fit the X08Plus frames!!
Which fits the X08 frames too!

This may be old news but gear-sets are now available for the X08/+ so I went ahead and put X08+on the flaps of my latest build. I prob would have gone with the HS08 had they been available as I was considering the X10 minis.

Maybe I'll upgrade to the HS08 depending on how the XO8+ do.
Last edited by Kirkerik; Jun 13, 2020 at 06:18 PM.
Aug 29, 2020, 12:59 PM
Registered User
planekrazy's Avatar
Jason, thank you for posting about these newer servos. Nice improvements over X08 Pluses.

Thomas/ArmSoar, thank you for stocking these servos. My order arrived earlier than expected yesterday.
Aug 29, 2020, 02:26 PM
RCG Admin
Jason Cole's Avatar
Thread OP
Nice! Enjoy!!
Sep 09, 2020, 01:46 PM
Registered User
Aaro's Avatar
Hi
I have now tested 4 of these servos in my light ExplorerQ. I originally found the KST HS08 very interesting; weight vs. physical dimensions vs. strength are quite exactly what light F5J model's wing needs. And I have had only good experience with X08/plus and X10Mini.

So, I ordered 4 and installed them to ailerons and flaps, using Servorahmen's IDS-systems everywhere.

Quite soon I found out that either I had very bad luck with the servos, or, as it seems, there are quite severe quality issues in the first delivered patch. This is nothing new with KST; one should not buy mark1

Pre-flight issues:
  • 1 out of 4 servos had tremendous free play / slop already when i unboxed it. My distributor of course replaced the servo without questions.
  • The servo axle's dimensions do not match the IDS set's arm; there is free play also there. Servorahmen was informed about this. I used some epoxy to remove the free play.

From the beginning the free play in the servos was quite adequate, identical to X08plus which shares the same gears, although with big flap the effective slop multiplies quite fast due to dimensions. Shortest servo arms were used, at cost of maximum deflection. Still enough deflection available.

The most interesting part of this trial was about HS08's ability to operate big flaps. And there is enough power for that use, deflecting the flaps from fast speed was completely ok. Happy so far

Anyway, after about 50 flights there is quite awful free play in every surface, and 2 of the servos started showing multipurpose capabilities; they can be used also as thermometer / sun shine indicator as centering started to drift quite much due to changes in ambient temperature. The biggest problem was the tremendous double centering in right flap; with the very geometry , center drifted about 4 mm depending on direction to which the flap was moving. It is quite irritating when the amount of camber in some flight modes is less than half of that

Just for general information: IDS-systems are installed perfectly, without twist, excess friction removed, like in ~10 IDS-equipped wings I have installed earlier. Supply voltage has no effect on double centering, I tested the whole range. There is no mechanical slop in the systems, so everything comes from the servos. Glider was and will never be landed flaps down; just normal use without any abuse.

Here are some videos. First of all, this is how decent servos (I do not mention what they are ) should work in a F5J glider. There is no free play. There is no temperature drift. Centering is perfect; it is easy to set the deflections and camber precisely as you want.

Here is the centering of a decent KST HS08. The length of the pointer is 150 mm. All 4 servos were like this in beginning.

Here and here you can see the double centering that was developed to right flap servo after some use. It is clear that the connection between main axle and the component measuring deflection is loose.

To conclude this episode... still interesting servo, and I continue using the 2 best pieces out of 4 servos in Q's ailerons, but I really hope and also will wait that KST gets rid of quality issues.

Aaro
Sep 09, 2020, 05:51 PM
Registered User
Thank you for the videos. I was planning to order a full set.


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