Upgrade for 450XL CDE

[tdswan]

Hey all. I lay awake at night thinking helicopters (go figure)....It take me some time to get to sleep and I had a brainstorm the other night. Those of you with a T-Rex CDE (yellow CCPM version), will be interested to know look into this. I'm going to post these in succession so the pictures show up in each step.

You know how the elevator linkage seems to be on the slow side and has a lot of friction in it with all of the links and linkages? I've found another way around it while comparing the SE & SA to the CDE. Ever notice how those versions have the servos directly connected to the swash? There's a reason for this.....it eliminates slop and friction. I, for one have had my elevator servo fail possibly because of all the friction in this linkage setup.

I've devised a plan to eliminate some of the friction and slop with the elevator servo and it won't cost you a dime, if you've got an extra link of the right size laying around.

[tdswan]

What we do first is fit a servo in place where it would be mounted if it were an SE and trace or scribe a line around it to show where to cut.
Then CAREFULLY cut a hole in the frame slightly smaller than your lines for safety.
You don't want to cut too much out, just keep test fitting it and trimming until you get the hole right.
DON'T cut the area where the screws hold it in, just the size of the body to slip into the frame.

[tdswan]

Here's an overview of the cutout.

[tdswan]

Here's a spare servo plate I had laying round test fitted into the hole.

[tdswan]

You're going to have to go another hole out on the servo horn and cut off the unused end or it will hit the tail pulley just like on the SE/SA. IT's shown here with the linkage test fitted in place.

You'll have to make adjustments to your radio and end-points and such to get the swash to travel up and down level. You'll also possibly have to leave a little room to slide the servo front or back to get the linkage as close to vertical as possible. Make sure you get it as close as possible before you make your initial cut in the frame.

[tdswan]

Once you've got the fine adjustments made, you can go ahead and re-install the anti-rotation plate and clean up your wires. Then go fly and enjoy your new upgrade. I want to add that as of yet I have not test flown this setup, but it's now identical to the SE/SA configuration and all of my tests on the bench prove very promising. The swash moves beautifully and I see no downsides to this. If you don't like it this way, go ahead and re-install the old linkages. I don't feel the frame is compromised enough to hurt anything should you decide to. I've seen others cut the frames up on these a lot more than this and still fly it.

[tdswan]

I welcome any scrutiny that anyone can think of. It's purely an experimental modification and there's probably something I may not have thought of so please, pick it apart if you think it's a bad idea. I have noticed one thing you may have to modify, it may be necessary to grind just a tiny bit on the anti-rotation bracket. With full-up collective, if you push forward cyclic it may bind a small bit on the bracket.
Thanks for reading guys!

Troy

[vapochilled]

only thing I could think of was, does the swash now move the same amount per servo travel as it did before? if not, it may need the throws adjusting in the radio or by changing the rod position on the servo arm?
Otherwise that's a smart mod, should tighten her up no end!

[tdswan]

There was a slight geomety adjustment that had to be made. I had to go to a longer horn (just one hole further out) and yes, I did have to adjust the end points on the elevator channel in the radio. I just got done tweaking it a bit more and grinding the anti-rotation bracket. Now it's free and uniform throughout the travel. I'm pretty proud of this little idea. :D

There was just sooo much stress on the elevator servo in the original config. If I slid the collective up or down quickly, the elevator would trail the other two servos by a little bit. Now it's almost faster than the aileraon servos!

[vapochilled]

looks like a winner! when you going to get it airborn?

[tdswan]

Hopefully tomorrow if the weather's good. Otherwise at our indoor fly on Friday. I'll Keep you posted! Wish me luck!

[Helifino]

BRILLIANT!

[tdswan]

Well, I flight tested my new mod and it worked flawlessly! I had to trim it a bit but it could have been due to my moving my electronics around as well. My CG was different than before. I actually hadn't had a better night of electric flying in quite a while!

I'd recomend the mod to anyone! :D