FBL Gyro Fine Tuning with Spirit Pro

[Heliman450]

Hi all,

I think that my T-Rex 550 rebuild has now firmly entered the 'FBL Gyros' area rather than the heli area, which I'll link to here when complete in this thread. Here goes..........................

I've gathered a number of screen shots from my Spirit Pro software to include in the threads to follow. The main problem lies with the mechanical adjustment of the tail and what to enter into the Spirit Pro software. Given that the available mechanical adjustment of the tail rotor is limited to the threaded ends of the carbon tail rod, the only option left is inside the software. Obviously, I could carry out a modification to the tail servo location to give me the second mechanical option of moving the servo forwards/backwards to give an appropriate amount of adjustment to minimise the software adjustments. I have to admit that this process really should have been done more thoroughly some months ago. Why? I hear you asking...............

Well, resulting from the crash prior to my rebuild, I noticed that the ball link on the servo end of the tail link rod was broken and the thread was out of the link. Sorry, no picture available. I undertook to look further into why this was the case during the repair/upgrade process. Upgrade was to a DFC rotor head, by the way.

The tail rod is 640 mm long including the threaded ends. This is an earlier conversion to a 600-sized tail. The tail as fitted, is 672 mm long between the ball link centres. Now the first screen shot.



As you can see in the 'Subtrim (tuning)' area, the rudder is set for -101 against its previous -1. Whatever these units actually are doesn't matter, it's just loads more than previously to get the rotor blades centred. Obviously, this required correspondingly different settings for the 'Limits' as shown in the following screen shot.



The settings here were previously '54 Left Limit and 99 Right Limit'.

The tail was also wagging quite badly, which also needs to be addressed, but enough for now.

Any feedback on the mechanical side much appreciated before I share my own thoughts.

Thanks in anticipation.

 

[Smoggie]

Phil,

If it were me I'd get the servo centred mechanically before using so much sub trim. You should be able to get hold of longer ball links if you need to increase the length of the rod. The servo arm should be at 90 degrees to the rod when the tail is centred (with just a touch of pitch to counter torque).

Sub trim can be used to get the arm perfectly at 90 degrees if the adjustment on the splines doesnt get it there, but sub trim should not be used to make up for a pushrod that's not the correct length.

If you dont have any longer ball links let me know the size of the ones you are using, I might have some longer ones in my box of bits.

 

[Heliman450]

Phil,

If it were me I'd get the servo centred mechanically before using so much sub trim. You should be able to get hold of longer ball links if you need to increase the length of the rod. The servo arm should be at 90 degrees to the rod when the tail is centred (with just a touch of pitch to counter torque).

Sub trim can be used to get the arm perfectly at 90 degrees if the adjustment on the splines doesnt get it there, but sub trim should not be used to make up for a pushrod that's not the correct length.

If you dont have any longer ball links let me know the size of the ones you are using, I might have some longer ones in my box of bits.

Hi Steve, I know the downside of using excess sub trim to get round such things. However, the problem is that the servo is recessed into the body and fixed so that it's impossible to see it when installed. I checked the servo arm before fitting the servo into the heli and it is actually at 90 degrees.

To achieve the correct alignment on the rotor blades the links need to be screwed out too far on the threads. I could probably work out the actual discrepancy, but I will still be left with the same problem. My guess is that the servo needs to be moved about 6-7 mm out from the current (fixed) position if using the standard 600 tail push rod as supplied. Of course, this is fitted to a 550 body, so maybe the difference is in the location of the mounting holes for the servo carrier.

The current links come from a standard package and I covered this point in the previous thread noting the various numbers stamped on the links. I can measure them and if you can tell me the options of longer ball links, I can look into it. Another option is to drill a new set of four mounting holes at the appropriate location or make a slot on either side of the body to give the required range of adjustment.

With the current set up, my most favoured option is the slots.

 

[Smoggie]

If you can measure the overall length of the links i can easily check if i have some a bit longer.. That could (assuming I have some longer ball links) easily give you the 6mm that you are looking for without the need to start modifying the servo position.

 

[Heliman450]

Hi Steve, the shank of the link is 10 mm.

 

[Smoggie]

I have some that are 17mm shank length and the same thread and ball size. One might be all you need but I'll put a couple in the post just in case. Hopefully a regular envelope will get past your over zealous customs squad.

 

[Heliman450]

I have some that are 17mm shank length and the same thread and ball size. One might be all you need but I'll put a couple in the post just in case. Hopefully a regular envelope will get past your over zealous customs squad.

That's great Steve, thanks. Fingers crossed on the customs, letters are no problem. Where did you pick them up? Sounds like a very useful place to 'raid'. I'm always looking for solutions to problems of some sort or another and a box of bits is always a nice to have.

With my heli hobby, I always take a look around the other RC model parts just to see if they have a useful screw or such like.

 

[Smoggie]

Phil, I'm not sure where they came from to be honest. They might be swash links off a Thunder Tiger X50e but I'm not sure.

But if you are looking for ball links in the future Quick UK is a good source: http://www.quickuk.eu/cat/general_parts/control_balls___links.html

 

[Heliman450]

One of the packs is 22 mm to the centre of the hole, so that sounds the perfect choice in my situation.

Thanks for the link

 

[Heliman450]

I have some that are 17mm shank length and the same thread and ball size. One might be all you need but I'll put a couple in the post just in case. Hopefully a regular envelope will get past your over zealous customs squad.

Hi Steve, did you put the links into the post? Normally, a letter gets through from the UK in 3 days of posting.

Cheers!

 

[Tony]

I think you are talking about a mail service, but if you are talking about the links in Steves reply, that was put in by forum software.

 

[Heliman450]

I think you are talking about a mail service, but if you are talking about the links in Steves reply, that was put in by forum software.

Hi Tony, hope all's well. Yes, I'm talking about the two ball links he kindly offered to send me to help lengthen the rudder control rod. My solution was a bit more invasive given that I don't have ready access to links with a longer shank. I could order up stuff from the website he gave me but I'd have to make it a package that's worth the P&P charges, import duty etc.

Cheers.

 

[Smoggie]

Phil,

The links were sent on Monday so assuming your Customs people dont mess things up you should have them any time.

 

[Heliman450]

Phil,

The links were sent on Monday so assuming your Customs people dont mess things up you should have them any time.

Hi Steve, great thanks.

It's only packages, which go through customs. If it's a normal or padded envelope they usually come through in a few days so probably tomorrow. When I ordered up my new heli and collected the transmitters I had a look round for any other possibilities to achieve the same end. There were a couple, but I think the bigger links are the best solution.

 

[Smoggie]

Yeah, the longer links should do the job fine. i've used the same trick on my helis before. I know they are a good secure fit on the 550/600 pushrod because i tried them on a spare one i have, but just be aware that about 2mm at the outer end of the hole is unthreaded, so dont screw them out too far or they might pull off.

 

[Heliman450]

Yeah, the longer links should do the job fine. i've used the same trick on my helis before. I know they are a good secure fit on the 550/600 pushrod because i tried them on a spare one i have, but just be aware that about 2mm at the outer end of the hole is unthreaded, so dont screw them out too far or they might pull off.

Cheers Steve, the links arrived this morning in the post. Good thinking that you put them in the envelope the way you did as there was a small cut in the envelope caused by a sorting machine no doubt. It would have been big enough for them to slip out of.

 

[Heliman450]

Hi all, the rod is newly fitted and needed one of each link i.e. 1 x 22mm & 1 x 10mm shank length. Total length is now 668mm centre to centre ( C-2-C).




Here are the before and after screen shots from the Spirit software. As you can see, the sub-trim is now zero and the left/right limits are the same. Next job is to test it at the field

 

[Heliman450]

Hi all, latest update on this........ I managed to get to the field yesterday but didn't have chance to sign in here until now. After setting up the tail and capturing the screen shots imagine my dismay when the tail was still twitching badly. Errrrrr, what can that be I asked myself or words to that effect.

I had a look into the Tx. and discovered that it showed the Spirit Pro was set for 'Vertical' mounting but felt certain that the software wasn't set for this. I took my laptop to the workshop today to check it out and the software was indeed showing '180 degrees Horizontal' as I expected. I made the change in the Tx. to correct it and the software changed to 'Zero degrees Horizontal'. I then changed the software to '180 degrees Horizontal' again. I re-checked the Tx. and there was no change so both were in agreement showing 'Horizontal'. (Note that the Tx. only shows the basic orientations, not the various options within the possible orientations).

The only explanation I can give is that I did a firmware update in my Jeti DC-14 during the rebuild of my T-Rex 550 and this must have resulted in the conflict. Something to watch out for. Yes, I know they tell you to check everything out following an update, but I never considered this to be a problem thinking that the Tx. only shows what the software is set for. It was my first Firmware update since the original setting up.

Despite the wind being very strong, I went quickly to the field and did a test hover. No twitching apparent . To be 100% sure, I intend to go again tomorrow so it's looking good for me to continue with my practice and also any further fine tuning of the Spirit Pro.

 

[Heliman450]

Hi all, looks like all's well now. Since the synchronisation of the Jeti and Spirit software the tail's behaving itself. Today, I managed to complete two batteries' worth of testing after the wind died down. Under normal circumstances, I'd have probably gone yesterday but the wind was still too strong to take the risk even though I felt confident in having tracked down the cause. I've got some video of the heli's problem before resolving the issue together with today's test, so if anyone wants to see it, then I can have a go at publishing it this weekend.

Bye now!

 

[Heliman450]

Hi again, great to see that the site's back up and running. I lost my video from the thread I published this morning so here goes again................

[video=youtube_share;Wq_lI9e9KF8]https://youtu.be/Wq_lI9e9KF8[/video]

I also thought that I can hear a rattling noise on the video that isn't there in real life. Let me know what you think.

Just to repeat. The problem was that the Jeti was showing the orientation of the gyro as vertical, when in fact, it is horizontal and the software agreed. Also, the Jeti doesn't have all the same options, so the horizontal is actually 'horizontal, 180 degrees'. I changed the Jeti from vertical to horizontal and the software changed to 'horizontal, zero degrees'. When I selected the 180 degrees option, the Jeti stayed with 'horizontal'.

During my 550 rebuild, I updated the firmware in the Jeti, so the conflict came during this process. Something to be careful of.

Bye now!