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 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:
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!).
I have done this upgrade already years back on the Raptor 50 V1
So for me this upgrade really works!
So after this lengthy explanation, here is the
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
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
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
The upgrade described above is
currently produced by
means that this upgrade is available to you all!