PowerHD Storm 4 HV BRUSHLESS servo from Redwing!!!

[FireDawg]

https://www.youtube.com/watch?v=rEwZkggtstE

Hey guys, I got my hands on an amazing new servo. I'm going to be putting it on the rudder of my 50cc Extra 300. I'm using the Redwing Pro Series red powerbox which is perfect for running high voltage servos because it keeps the voltage to the RX at 5v while sending full battery voltage to the servos. Unfortunately the rest of the plane has XQ Power 4020 digitals that can't handle high voltage, so I'm using two 6.6v LiFe packs.

This brushless servo is a pretty impressive unit. The entire exterior is solid aluminum. No plastic covers on the top or bottom. I've had to get replacement cases for servos that have been through a crash, but I don't see this happening with the Storm 4. It's got titanium gears, dual ball bearings on the shaft (absolutely no play in this servo) and is fully weather sealed.

The specs on the Storm 4 are pretty impressive. At 7.4v it puts out 347 oz/in of torque and the speed is .085 sec! At 6v it produces 291 oz/in and the speed is .10 sec. Still pretty respectable.

One of the coolest aspects of the brushless servos is that they are efficient. Unlike strong digital servos that consume large amounts of power, the brushless servos only use the amount of power needed to perform the movement signaled by the radio, but no more. So since these HV servos use much less power, smaller and lighter LiPo flight batteries can be used.

Since the Storm 4 has similar power and speed ratings at 6v as my XQ 4020, I wanted to see the difference in how they operated next to one another. I put them on a board and checked some movement. The brushless servos are said to operate smoother, and from what I can see, it's true. The Storm seemed to be in perfect sink with what my stick movements were while the XQ had some variation. The XQ hesitated on initial movement, then moved quickly to catch up. It just seemed to move a little, slow down, then move again to catch up. It did the same thing coming back to center. It would get close, hang up, then drop down quickly. The Storm's movement was very smooth and linear. It's also darn near silent. No buzzing like digitals. Both servos come back to center perfectly.

Here is a video of them side by side...
https://www.youtube.com/watch?v=KWHa4-pbWQM

EDIT...here is a much better comparison video
https://www.youtube.com/watch?v=mA3Mg5gRVQ8


If anyone else has some experience with the Storm servos let me know your thoughts. I hope to get some flights on it within the next couple days and report back!

If you'd like to get your hands on the Storm 3, 4 or 5, you can get them here.
http://www.redwingrc.com/index.php?main_page=index&cPath=12&zenid=2OCTy3cLGKgmzypQxJTiR3
Redwing has the best customer service in the business! You won't be disappointed.

Jeremy

 

[SnowDog]

great review FireDawg...those Storm4's will rock on 7.4!!

very smooth transition throughout the entire range of movement.

I would be very interested to see you perform a torque test on these two servos now that you have done speed and centering.

 

[FireDawg]

I'm nervous about breaking one of them. I bet Tim at Redwing will end up doing a torque test. He's done some before.

I did do another speed test with the Storm running on 7.4v and the XQ on 6.6v.
https://www.youtube.com/watch?v=Wd597DEUTIY

Jeremy

 

[3dNater]

Are those servos plugged into the same channel?

 

[FireDawg]

Yes. They were on the same channel. There was absolutely no way the comparison was not an exact "apple's to apple's" test. The Redwing power box has two outputs for each channel, so I plugged them both into my Aileron channel (channel number 1).

However, In the last speed test I wanted to operate the Storm with 7.4v so we could see each servo running at their absolute fastest. So I used a separate rx on 6.6v to run the xq4020 and put a 7.4v Lipo on the power box to run the Storm 4.

Since both receivers are linked to my tx, I simply had both servos plugged into channel one on their respective receivers and turned them on. The only variable is that maybe one receiver is slower at receiving the info from the tx and sending it to the servos. But I HIGHLY doubt that would happen. They seemed to operate in exactly the same fashion as they did during the resolution and centering tests when they were on the same receiver...

Jeremy

 

[3dNater]

Ok, I was just concerned that there could be expo in the xq and not in the power hd since it honestly looks like expo. Crazy!

 

[FireDawg]

There is expo programmed into channel 1 on my radio as it's my Aileron channel, but they were on the same channel so they should be moving together.

It kind of does look like expo except it's it's only in the first 1/3 or so of the movement (well the biggest deviation at least), then catches up. Then there is a little "pulsation" if you will. It just seems to have slow spots throughout the travel.

Now this little bit of deviation won't really effect me too much because I'm not an expert pilot or flying a heli with the XQ 4020s. But it most definitely will effect some other pilots. They obviously aren't on par with the Storm, but they are still a pretty darn good servo for the price.

Jeremy

 

[3dNater]

Is it possible to run the test again with zero expo? I think the difference could be deviations in how the different servos are interpreting the expo in which case it could be tuned to feel right and isn't necessarily a quality difference.

 

[3DeltaFly]

Nice testing and review, thanks! I've had my eye on those Storm brushless servos for an upcoming 100cc project, and have been looking for reviews on them and etc.

BTW, expo is only a function of the transmitter. All that the servo "sees" is the transmitted "position information". In the speed test video, it is apparent than the Storm-4 is not only faster, but in the mid range of motion the Storm-4 exhibits much finer resolution. That is either in the design of the Storm-4, or the receiver controlling the XQ servo does not have the same resolution capability as the receiver controlling the Storm-4. I.e. 1024 bits compared to substantially more or less in the 2nd receiver, or are both receivers identical?

 

[FireDawg]

They are hooked to the same receiver in all tests except for the last one where the Storm is on 7.4v and the XQ is on 6.6v. But in that test they are on identical receivers. Both were the Futaba 617.

And I did do the test again without expo in the radio. No changes in function to note, so I didn't waist the hour uploading the video. Visually, both servos functioned the same as they did in the other tests.

I've put some flights on the plane but haven't had anyone to take any video for me. So far, the Storm has felt great. I just wish I was a good 3D pilot so I could get the full benefit of the performance of the Storm.

Thanks,
Jeremy