3rd Bearing Upgrade

12/28/08

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3rd Bearing Upgrade
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News flash!

The upgrade described below is currently produced by QuickUK. This means that this upgrade is available to you all!

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Raptor 50 3rd bearing upgrade.

As all experienced Raptor 50 flyers know, the pinion bearing of the Raptor 50 fails quite often. Unfortunately, replacing this bearing is a lot of work. I have completely addressed this problem with a small and simple upgrade. This upgrade ensures that the bearing will never fail anymore. Let me start by explaining the problem of this bearing.

The Problem.
The Raptor 50 has a design flaw in the pinion bearing support. The pinion bearing is the only loaded bearing of the Raptor 50 that is spinning at full engine RPM and that does not get lubrication (the bearings in the engine are of course lubricated by the oil in the fuel). This makes it very important that the bearing is loaded in the proper directions (for which the bearing is designed) since it is already fragile due to this.

Unfortunately, the pinion is only supported by one bearing on the Raptor 50. This is the actual problem why this bearing fails so often. The pinion is of course forced sideways due to transferring the torque of the pinion onto the main gear. This together with the fact that the pinion is only supported by one bearing makes the pinion tilt. This loads the bearing not only in the radial direction, but actually tries to tilt the bearing. This is something for which a bearing is not designed, it has only very limited capabilities to take this load!

But what about the one way bearing in the clutch and the bearing in the clutch bell?
Some people may think that the start shaft is actually supported by two bearings. It is not. The reason is that the one way bearing can not properly take any radial force when disengaged (the normal condition during flight) since the needles are moving outward in the bearing. So the start shaft is in principle only supported by the top bearing in the frame and the bearing in the clutch bell. But of course the entire clutch bell can move sideways because the pinion (and thus the clutch) is only supported by one bearing.

Now if you spool up the engine, and transfer the torque of the pinion to the main gear, the pinion will tilt, and in that slowly destroy the pinion bearing. That is the problem. You could easily see this happening on the V1 Raptor 50. The start shaft always showed signs of damage where the inside of the pinion touched the start shaft due to this tilting. The solution "to seeing this evidence" on the V2 is making part of the start shaft thinner (compared to the overall thickness of the start shaft which was increased on the V2) where the inside of the pinion would otherwise touch the start shaft. Now you don't see any chafing damage on the start shaft anymore. However, this does not solve the problem, it only removes one symptom. Still the bearing on the pinion breaks down as explained above.

Now the cure to this problem.

I have added a third bearing which adds an additional support for the pinion on the start shaft. This solves two problems:

bullet1) The pinion is now supported on two bearings (one above the teeth, and one below the teeth). This removes the tilting problem of the pinion with reference to the start shaft. If the start shaft would now have two proper bearings, then the problem would be solved.
bullet2) The start shaft is now supported by two bearings. This is true since the start shaft is now supported by this additional bearing onto the pinion, and again the pinion is supported in the frame.

1) and 2) together ensure that the start shaft can not tilt anymore, nor can the pinion tilt anymore. Both the pinion and the start shaft are now supported by two bearings as it should. This ensures that all the bearings are only loaded in a radial direction for which they are designed. This completely solves this problem.

This upgrade has another good side effect, the teeth of the pinion line up much better now with the teeth of the main gear under load. This makes the drive train more stable (the old wha wha problem of the Raptor is also properly fixed) and less energy is consumed due to the reduced friction between the gears (so you have more power!).

Concluding

I have done this upgrade already years back on the Raptor 50 V1 and:
bulletI never had any wha-wha since,
bulletI never had a clutch fail since,
bulletI never had a bearing fail since.

So for me this upgrade really works!

So after this lengthy explanation, here is the solution

Ok, here is the design of the solution. I have added drawings and photos of my 3rd bearing upgrade for the Raptor 50. All the parts are completely modeled in 3 dimensions with the actual dimensions etc. The upgrade does not need a change to any other part, nor to the main frame.
 

Here you can see the entire drive train stack of the Raptor 50 modeled in a 3D modeling program. The blue bit is the actual upgrade with the additional red bearing inside the upgrade.
 

Here you can see the additional 3rd bearing from the top.


From the pictures above you can easily see that the pinion and the clutch can no longer tilt with reference to the start shaft since the pinion is supported by two bearings, and that the start shaft can no longer tilt with reference to the main frame since it is effectively supported by two bearings.

Here you can see how the 3rd bearing upgrade is pressed on the top of the pinion.

 

Here you can see an exploded view of the new drive train of the Raptor 50.

 

Here you can see the produced upgrade.

 

Here you can see the upgrade with the additional bearing in the top. Note that I modeled the upgrade such that you can simply use a bearing from the clutch bell.

 

Here the upgrade with the additional bearing is mounted on the pinion (press fit).

 

And finally here you can see the upgrade with additional bearing sitting in the main frame. It just drops in, it does not need a change to any other part.

 

As indicated above, this neat upgrade solves all the problems of the drive train of the Raptor 50, and improves the already very good design of the Raptor 50 to a level where it will be very difficult to beat! If you have any questions, then just send me an e-mail.

The upgrade described above is currently produced by QuickUK. This means that this upgrade is available to you all!

 

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