CSM SL630 Gyro

The following is a review of the CSM SL 630 gyro. This gyro uses the same silicon sensor and internal programming logic as the CSM 720.

Obviously the CSM SL 630 gyro is slightly different to the CSM 720, the main difference being that you cannot tweak all of the internal parameters on the CSM SL 630. However, you are still able to configure a couple of options on the gyro but nothing like the plethora of options available on the CSM 720. Aside from this the two gyros are identical.

 

Programming the CSM SL630

The CSM SL 630 is programmable through two different programming interfaces. The first of these is the ability to set a jumper on the gyro itself. One position of the jumper will set the gyro output frame rate to 250 frames per second, the other jumper position will set the output frame rate to 333 frames per second. This allows configurability of the gyro to match the servo being used.
The second programming option is accessed through the quick setup interface and allows you to turn "E" mode on. This mode is designed specifically for small electric helicopters like the T-Rex 450. What setting this mode on does internally within the gyro is to set the acceleration gain to 140. This setting gives a much better/controllable tail on small helicopters.

I have included below a copy of the quick reference guide which shows the location of the jumper and also the light to show whether "E" mode has been activated. 'E' mode is activated through the quick setup function.

Gyro Mounting

The gyro was mounted on the T-Rex 500 in the usual position on top of the tail boom clamp. I used basic foam tape to mount the gyro, this is just cheap fairly compact standard gyro mount tape available from most heli shops. CSM do two mount pads but I found the thick one too soft and the thin one was just too hard a mount. So I defaulted to the basic stuff you would normally mount something like a GY401 on. This works fine.

Tail Servo

I chose a standard tail servo, CSM gyros in my experience don't get on well with slow or inaccurate servos. This meant a 9650 or 9257 were not really suitable. Instead I opted for a JR 8900G which is a superb tail servo. Additionally as the CSM 630 does not support 760 micro second pulse width, servos such as the Futaba 9256 or Futaba BLS 251 will not work with it. As the JR 8900G supports 333FPS I inserted the jumper to set the faster frame rate.

Initial Setup

All CSM gyros should be setup to hover with no drift in rate mode before using heading hold mode. Normally this is done by flying the model. However, there is a much quicker way for the T-Rex 500. Firstly set the ball on the servo horn to three holes out from center (JR servo disc). Next power up in rate mode and make sure the servo ball is positioned in the correct hole on the disc to be exactly central such that both left and right rudder have an equal throw. Now remove the servo disc and rotate it one spline such that the ball is now offset towards the front of the model. So now we have unequal throws with less throw when the ball is moving towards the front of the model and more throw when moving aft. The reason we do this is to account for the fact that the T-Rex 500 tail grips are not offset and you therefore end up with unequal tail throw unless you offset the disc as we have done.

The servo disc can now be secured with the screw, we won't be adjusting it any further. Now get some digital calipers and measure the gap between the tail pitch slider and the tail case (see picture). The gap should be 6mm in rate mode with the rudder stick at center. This is the perfect position for no drift in rate mode and eliminates the need to do this in the air, although I would still recommend some fine adjustment. With the gap at 6mm secure the tail servo on the boom. Now you must follow the CSM setup instructions to make sure the gyro and servo direction are set correctly using quick setup. The gyro must not be used in 'E' mode on the 500 or have the vibration filter enabled, this should not be necessary on an electric model.

 

note1: Picture shown is of a BLS251 which will not work with a CSM 630. The picture is just to show the offset of the servo horn.

Flight Review

The CSM 630 behaves in flight almost identically to the CSM 720 in this setup. However, the 630 does not allow fine adjustment of the pirouette stop rates. This means that there is a very minor bounce on left tail stops and it cannot be corrected. I tried various servo horn sizes and adjustments but none got rid of it completely. The bounce is very very minor and only noticeable on very fast hard stops.

Outside of this small issue I found myself immediately at home with this gyro, it flies just like the 720, excellent piro consistency and very easy to control the exact stop points for four point tic tocs and those kind of moves. Like all CSM gyros it excels at piro moves and very nice piro wall of deaths, piro loops and chaos can be perfromed without a whippy tail.

In order to illustrate just how good the tail was now behaving we shot a video which at the time was testing a motor but in retrospect was a very good showcase for the capabilities of the CSM SL 630 gyro.

 

 

 

 

 

Conclusion

The CSM SL 630 gyro is designed to be a cutdown version of its much more configurable 720 brother. In this regard it works very well in that there is no access to all of the parameters that are usually adjusted using the CSM PC interface. Instead a small jumper is used plus quick setup in order to configure the gyro.

Given how easy this gyro was to set up (providing you match it to a nice high-speed servo) there is no doubt that it can provide excellent performance in the T-Rex 500.

Those familiar with the 401 gyro should feel right at home using the CSM SL 630 as it feels very similar in response. However, the 401 fails on constant pirouette rate whereas the CSM excels in this area.

Overall I am extremely impressed with this gyro and when matched with a good fast tail servo it offers excellent performance. My one reservation is that it really isn't much cheaper than a CSM 720 and personally I would much rather pay a little more for that excellent configureability.

 

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