GW-9958 with WL-V911 Swash Plate Double-Decker Mod - RC Groups
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This thread is privately moderated by Heli Pad, who may elect to delete unwanted replies.
Feb 09, 2012, 04:16 PM
Against Helicopter Cruelty
Heli Pad's Avatar
Build Log

GW-9958 with WL-V911 Swash Plate Double-Decker Mod

The 9958 stock swash plate has just one pair of ball links. The distance between the balls (end to end) is 12.4mm. By contrast, the stock swash plate of the new comer, v911, has two sets of ball links. Even the short ones are 16.4mm apart, and the long ones are 20.4mm apart. In theory, the v911 swash plate will provide a lot of throw for the cyclic actions.

Parts Required
One v911 swash plate assembly, which consists of an upper swash, and a lower swash. The bearings in the swash plate do not come with the replacement part.

It would be nice if the v911 swash plate directly replaces the 9958ís, but that is not the case. For starter, the guide pin in the v911 swash plate is in a different position. Fortunately, it is very easy to simply swap out the upper swash and retain the lower swash and bearings; therefore, no change to the guide pin configuration. However, there is another issue. The v911 upper swash is much lower than the 9958 swash, effectively pulling the lower plate up. When connected up to the flybar and the head assembly, the new combo rides too high around the shaft and the pin guide from the frame cannot effectively guide the anti-rotational guide pin from the swash plate.

Previous attempts to do this mod (using a similar swash plate from Solo Pro) involves either extending the pin guide taller by gluing on carbon fiber rods, or making a custom shaft that is shorter. This mod uses a different approach to solve the same problem.

Mod Details
First, take the 9958 swash plate apart by separating the upper swash and the bearings from the lower swash. Next, clip off the arms that are used to attached to the servos from the v911 lower swash. At this point, the only thing left on the v911 lower swash is the guide pin. BTW, it should be mentioned that guide pin on the v911 lower swash is extra long. The same pin is 5mm long on 9958, 7mm long on Solo Pro, and 9mm long on v911. Next, turn the v911 lower swash upside down, apply tiny bit of CA and glue it to the 9958 lower swash, bottom against bottom, and ensuring that the two guide pins line up exactly. Let dry, then re-install the bearings on the 9958 side. Lastly, mate it with the v911 upper swash and the transformation is complete.

Bottom Line Numbers
Essentially, the upper portion of this transformation is the old 9958 lower swash with the v911 upper swash. The bottom half is the v911 lower swash attached to it to make up of the height difference that the upper swash creates, lowering the guide pin position, while giving it an extension by 4mm. The original weight of the stock swash plate is 1.08g. The new combo is 1.28g. The difference is only 0.2g. However, the distance between the balls went from 12.4mm to 16.4mm, with the option of going to 20.4mm in advanced mode.

Performance Test
The glued on v911 lower swash worked perfectly during tests. It never jumped the guide once. The 0.2 g weight gain was not noticeable. If you think that your 9958 flies fast, then this thing is insane after the mod. I initially had it on the long balls. On FFF, this thing dipped its nose so much it was literally going vertical! It is a good thing that I went out with Daryoon and Jlk69 this morning. Daryoon is a much better test pilot. My 9958 mod shines in his hands. Even so, 20mm proved to be a bit much for us at this time.

After dialing it back to 16mm, the new bird proved to be much better. The cyclic was quick and aggressive. The 9958 was making moves that Iíve never seen before. However, my Nano Tech batteries were not able to keep up with it. They did not provide enough thrust. After switching to Daryoonís Hyperion, it was a different ball game. The 9958 took off, turned nicely, and was penetrating wind.

This mod definitely offers benefits and new potential. Itís very inexpensive, and very easy to make. I just need to learn to fly more aggressively with this 9958.
Last edited by Heli Pad; Mar 14, 2012 at 08:52 PM.
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Feb 09, 2012, 06:46 PM
Team WarpSquad
Daryoon's Avatar
Good job and thanks for sharing.

I actually have a 9958 swash with a broken guide pin. This mod just brought that swashplate back from the dead.
Feb 10, 2012, 11:32 AM
Team WarpSquad
Daryoon's Avatar
What do you think will happen to performance if you reverse the two swashplates used?

Have the 9958 and it's servo arm on the bottom and the donor swashplate in the middle to extend the height of the swashplate. Kidda like my "cusker" mod that used the Solo Pro swashplate but without the difficulty of having to drill out the Solo Pro swashplate hub perfectly.
Feb 10, 2012, 01:58 PM
Against Helicopter Cruelty
Heli Pad's Avatar
Hmmm, Daryoon, I think I like your suggestion! If the lower half is a 9958 stock lower swash, it would retain the arms and pin. (Can't use v911 has the lower for obvious reasons). The upper half then could be any lower swash (9958 or v911) with no arms, no pin. It's even lighter, and I wouldn't have to lengthen the servo links.

I'm not sure how performance would be affected. I'm still running simulation in my head!!! LOL

Great idea!! Should we try it?
Feb 12, 2012, 12:46 AM
Against Helicopter Cruelty
Heli Pad's Avatar
Daryoon, I took your suggestion and made a Version 2, with 9958 lower swash at the bottom. The upper half is a v911 lower swash, and a Solo Pro upper plate!!! I like the Solo Pro upper better than the v911 upper, because the ball links have a much better fit with the linkages. They might look the same at first, but the v911 parts are much cheaper. You do get what you paid for.

The biggest improvement of V2 is: instead of lengthening the servo links to almost falling off the end of the rods, I actually have to shorten them by a couple of turns. As a result, the linkages feel much better. Will have to see the performance when I get a chance to fly them.
Feb 12, 2012, 12:50 AM
Team WarpSquad
Daryoon's Avatar
Nice job. Let me know if it flies the same or better. The servo's pivot point is now so low. Way below the plane the swash hub spins on.
Feb 12, 2012, 12:53 AM
Against Helicopter Cruelty
Heli Pad's Avatar
Let you know?!?! I think you're forgetting that YOU are the test pilot. Sometime next week, okay?
Mar 18, 2012, 04:39 PM
Registered User
What links are you using? I've used the 9958 ones, but they are to short and fall off the v911 balls:-(
Mar 18, 2012, 08:36 PM
Against Helicopter Cruelty
Heli Pad's Avatar
I'm using 9958 links. They are a little bit loose but they stay on. I'm not sure how you mean that they are too short??
Mar 19, 2012, 03:57 AM
Registered User
The link between upper swash balls and flybar let the new swashplate get too high. The guide pins gets also too high and jumps out of the holder.
Btw. I built V1 (a mistake as I can't go on lengtening the servo links without falling apart).
Could this be my problem ?
Mar 19, 2012, 12:48 PM
Against Helicopter Cruelty
Heli Pad's Avatar
Yes, if you look at the mechanism closely, you would find that the swash plates are "suspended" in space by the links, flybar, and blades, going around the shaft. Its vertical position is entirely determined by what is above it. Therefore, you change to a shorter (in terms of height) upper swash, you lose as much as 3mm of height, and the guide pin on the lower swash got pulled up and out of the guide. This is the whole motivation of the Double Decker Mod - to keep the pin in the guide.

Version 1 of the mod has the swash servo arms sitting high, because they are coming out from the top level of the double decker. Therefore, your servo rod has to been extended to almost the max. Therefore, Version 2 is much nicer (kudos to Daryoon), because the arms are coming out from the bottom level of the double decker, and your servo rods do not have to be extended. If anything, I found that you have to shorten them a little.

If you have started with V1, I found that it is possible to convert it into V2. I just did one a couple of days ago. Take the upper swash and bearings out of your V1 assembly. Flip the double-decker upside down and re-install the bearings and upper swash on the other half, and now you essentially have V2, as the arms are sticking out from the bottom half!!! Try that and see if your servo rods situation is better than before.

Note: I wish I took some photos when I made the switch. If any of the above instructions is unclear, let me know, I could go back and shoot some pictures.
Mar 19, 2012, 02:58 PM
Registered User
Arghh, now I've got the opposite : can't turn the links much lower for trimming.
I have to check it again (no time left now) and get back to you
Mar 19, 2012, 06:05 PM
Against Helicopter Cruelty
Heli Pad's Avatar
There is a possibility that you might have to cut a mm or so off the tip of the rods, but it sure beats having to extend them to the point of falling off. I rather have them all the way down and secure. Play with it. I think you are getting real close to perfecting it.
Apr 02, 2012, 10:35 AM
Registered User
Originally Posted by Daryoon
Nice job. Let me know if it flies the same or better. The servo's pivot point is now so low. Way below the plane the swash hub spins on.
I think this is the most relevant post here so far. I'm not sure you're gonna get better performance with this mod. As Daryoon said, the pivot point for the swash is now way low. As far as i know these planes, servo pivot point and swash pivot point, should be as parallel as possible for better movement.

I could be wrong though....
Last edited by BrandonR.; Apr 02, 2012 at 11:28 AM.
Jan 14, 2014, 06:23 AM
Yoyoer trying to fly.
Rizkiyoist's Avatar
Snap! I think I'm gonna get a 9958 now instead of going for a v922 :O

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