New Cesaroni Motor Mounting

[Dave Camarillo]

So I was figuring out how to mount the new motor casing in the
airframe and ran into this issue (see picture). The forward closure on
the new motor sits higher then the old one, and if I simply extend the
retaining bracket it will interfere with the avionics.

The easiest option would be to shorten the mid plate by a hole or two
and move everything up, but I know that module is pretty packed. I
could also use countersunk screws and/or thinner plate for the top
most flat bar, which would help but wouldn't completely solve the
problem.

Alternately, we could skip dealing with this and just design a motor
bulkhead with the strain gauge that will properly fit. (hand waving
here, this is more complicated then it sounds, but there have been a
couple good ideas so far).

Thoughts?

Thanks,
-Dave

[r***@q7.com]

Hey,

Probably not understanding things as well as i should from the picture,
ignore me if i'm stupid, but it appears that a spacer would lower the
top attachment enough. Does this cause other, worse problems?

Post by Dave Camarillo
So I was figuring out how to mount the new motor casing in the
airframe and ran into this issue (see picture). The forward closure on
the new motor sits higher then the old one, and if I simply extend the
retaining bracket it will interfere with the avionics.
The easiest option would be to shorten the mid plate by a hole or two
and move everything up, but I know that module is pretty packed. I
could also use countersunk screws and/or thinner plate for the top
most flat bar, which would help but wouldn't completely solve the
problem.
Alternately, we could skip dealing with this and just design a motor
bulkhead with the strain gauge that will properly fit. (hand waving
here, this is more complicated then it sounds, but there have been a
couple good ideas so far).
Thoughts?

[Dave Camarillo]

I'm guessing you mean putting a spacer on the face of the bulkhead
that bares the thrust of the motor. That would effectively lower the
whole retainer assembly. We have about 0.625" of bore on the bulkhead
that the motor casing slides into, we could probably reduce that down
to as little as 0.2". I think a ring, that sat on the face of the
bulkhead, and attached to the top portion would do the trick...

Off the top of my head I can't think of any mechanical problems with
this approach. Perhaps that, combined with the countersunk screws, and
we could avoid modifying the avionics pieces...

Post by r***@q7.com
Hey,
Probably not understanding things as well as i should from the picture,
ignore me if i'm stupid, but it appears that a spacer would lower the
top attachment enough. Does this cause other, worse problems?

Post by Dave Camarillo
So I was figuring out how to mount the new motor casing in the
airframe and ran into this issue (see picture). The forward closure on
the new motor sits higher then the old one, and if I simply extend the
retaining bracket it will interfere with the avionics.
The easiest option would be to shorten the mid plate by a hole or two
and move everything up, but I know that module is pretty packed. I
could also use countersunk screws and/or thinner plate for the top
most flat bar, which would help but wouldn't completely solve the
problem.
Alternately, we could skip dealing with this and just design a motor
bulkhead with the strain gauge that will properly fit. (hand waving
here, this is more complicated then it sounds, but there have been a
couple good ideas so far).
Thoughts?

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http://lists.psas.pdx.edu/mailman/listinfo/psas-airframe

[Dave Camarillo]

In talking with Tom, another thing that occurs to me, it would be
possible to bolt a large-diameter threaded piece to the forward
closure, then put the same large diameter threaded piece (female) on
the blulkhead, and thread the whole thing into that. Imagine the
forward closure having a 2" diameter thread at the top, that bolts
thinly to the 3/8" screw in the actual forward closure. This would
take some machining effort, but is doable...

On Sun, Aug 12, 2012 at 3:59 PM, Dave Camarillo

Post by Dave Camarillo
I'm guessing you mean putting a spacer on the face of the bulkhead
that bares the thrust of the motor. That would effectively lower the
whole retainer assembly. We have about 0.625" of bore on the bulkhead
that the motor casing slides into, we could probably reduce that down
to as little as 0.2". I think a ring, that sat on the face of the
bulkhead, and attached to the top portion would do the trick...
Off the top of my head I can't think of any mechanical problems with
this approach. Perhaps that, combined with the countersunk screws, and
we could avoid modifying the avionics pieces...

Post by r***@q7.com
Hey,
Probably not understanding things as well as i should from the picture,
ignore me if i'm stupid, but it appears that a spacer would lower the
top attachment enough. Does this cause other, worse problems?

Post by Dave Camarillo
So I was figuring out how to mount the new motor casing in the
airframe and ran into this issue (see picture). The forward closure on
the new motor sits higher then the old one, and if I simply extend the
retaining bracket it will interfere with the avionics.
The easiest option would be to shorten the mid plate by a hole or two
and move everything up, but I know that module is pretty packed. I
could also use countersunk screws and/or thinner plate for the top
most flat bar, which would help but wouldn't completely solve the
problem.
Alternately, we could skip dealing with this and just design a motor
bulkhead with the strain gauge that will properly fit. (hand waving
here, this is more complicated then it sounds, but there have been a
couple good ideas so far).
Thoughts?

_______________________________________________
psas-airframe mailing list
http://lists.psas.pdx.edu/mailman/listinfo/psas-airframe

[Andrew Greenberg]

Perhaps that, combined with the countersunk screws, and we could
avoid modifying the avionics pieces...

The avionics module is bolted to the aeroshell at the bottom D blocks,
and the holes for those countersunk bolts are *right* below the patch
antennas so they can't be raised up. That said, we could add another set
of D blocks and lift that bottom plate up, but Dave's right, it's going
to get *really* tight in there. Anything we can do to avoid mucking with
the avionics space would be great.

Andrew