Drilling a solid crankshaft

Drilling a solid crankshaft



Has anyone had experience with a solid Lycoming crankshaft modified
(drilled) to open oil passages required to control a constant speed prop?



I'm asking for a cousin with a friend who knows a guy with an airboat.

Does he need a constant speed prop on the airboat???



Ole Moyer wrote:
Drilling a solid crankshaft



Has anyone had experience with a solid Lycoming crankshaft modified
(drilled) to open oil passages required to control a constant speed prop?



I'm asking for a cousin with a friend who knows a guy with an airboat.

They are already drilled! Need to remove front plug and insert rear plug in
the front of the crank. Can be done without disassembling the engine.


"Scott" wrote in message
...
Does he need a constant speed prop on the airboat???



Ole Moyer wrote:
Drilling a solid crankshaft



Has anyone had experience with a solid Lycoming crankshaft modified
(drilled) to open oil passages required to control a constant speed prop?



I'm asking for a cousin with a friend who knows a guy with an airboat.

I think he's referring to the hole drilled in the side of crankshaft;
the hole that allows the pressurized oil to enter the front hollow part
of the crankshaft.

I had an RV-6 with a Lycoming E2A engine and had planned to convert it
to constant speed. Assembled all the needed parts, governor, prop, nose
cone, etc and then pulled the old wood prop from my engine. Imagine my
delight when I discovered that the previous owner of the engine had
replaced the original crankshaft (which would have had the hole in the
side of the crankshaft) with a crankshaft that did NOT have the hole and
crossover tube.

John

Cy Galley wrote:
They are already drilled! Need to remove front plug and insert rear plug in
the front of the crank. Can be done without disassembling the engine.


"Scott" wrote in message
...

Does he need a constant speed prop on the airboat???



Ole Moyer wrote:

Drilling a solid crankshaft



Has anyone had experience with a solid Lycoming crankshaft modified
(drilled) to open oil passages required to control a constant speed prop?



I'm asking for a cousin with a friend who knows a guy with an airboat.

We are not being trolled... unless that means looking for knowledge
among the group.

As for the airboat, maybe it's a really fast airboat. Or maybe the
guy doesn't want to admit that he's considering using a modified
crankshaft in an RV-6.

A Lycoming O-360A4A has a "solid" crankshaft. There are no plugs to
remove to open an oil passage because there is no passage to plug.
Think of a solid rod as opposed to a hollow pipe.

On the other hand, a O-360A1A has a hollow crankshaft, by removing the
front plug, an oil passage is opened to allow oil to flow from the prop
governor to the prop.

If a (hypothetical) solid crankshaft had a ½ inch holed drilled right
down the center, from the prop flange to the depth of the center of the
front main bearing (about six inches), AND a smaller hole drilled from
the side if the crankshaft into the previous drilled hole, that would
allow for control of a constant speed prop. Of course the crankcase
would also need to be setup properly.

I have seen this modification on a certified airplane. I'm not sure
that it was legal, but it was real.

My conservative (and less financially challenged) friends claim they
would never consider using a crankshaft modified in this way. My
engineering friends suspect the stress on the steel would be relatively
low in the center of the crankshaft.

Does anyone on the list have first hand experience on this subject?

"Ole Moyer" wrote

My conservative (and less financially challenged) friends claim they
would never consider using a crankshaft modified in this way. My
engineering friends suspect the stress on the steel would be relatively
low in the center of the crankshaft.

Does anyone on the list have first hand experience on this subject?

I do not have first hand knowledge, but that has never stopped me from
speaking out before. :-) Not I am not an engineer, so all opinions are
just that.

It is true that being in the center, the stress should be relatively low.
If the other hollow crank is the same otherwise, dimensionally, then the
extra material removed should make it no less strong than the hollow crank.

My question is this. Would the crank at its current state of heat treat,
allow a hole to be drilled using conventional methods?
--
Jim in NC

Airboats don't use constant speed props - their props get damaged too
often, CS is much more expensive than wood, and airboats use prop
pitches that are much lower than airplanes because they aren't going
nearly as fast

I've seen an airboat with a CS prop. The internal stops can
be adjusted to get the lower pitches necessary for airboat operation,
and the blades themselves could be twisted a bit to lower their overall
pitch.

Dan

wrote \
I've seen an airboat with a CS prop. The internal stops can
be adjusted to get the lower pitches necessary for airboat operation,
and the blades themselves could be twisted a bit to lower their overall
pitch.

Reverse thrust would certainly be a great benefit for an airboat, no?
--
Jim in NC

"Bashir Salamati" wrote in message
...
On 1 Nov 2005 12:04:18 -0800, "Ole Moyer"
wrote:

:A Lycoming O-360A4A has a "solid" crankshaft. There are no plugs to
:remove to open an oil passage because there is no passage to plug.
:Think of a solid rod as opposed to a hollow pipe.
:
:On the other hand, a O-360A1A has a hollow crankshaft, by removing the
:front plug, an oil passage is opened to allow oil to flow from the prop
:governor to the prop.

The solid O-360A4A cranshaft is worth about 70% more than the hollow
O-360A1A crankshaft. If your hypothetical airboater had the first and
wanted the second, he could call any engine rebuilder in the world and
trade. Since the crank is out of the engine already - he wouldn't
actually try to drill it IN PLACE, would he? - it would be a much
better idea to just get the right part before reassembling the engine.

If the hypothetical builder were smart, he'd actually get more than a
straight across swap out of the rebuilder. Maybe a rebuilt governor,
since the A4A doesn't have one.


Bashir,

I suspect you are referring to the value of an aerobatic crankshaft. A solid
crankshaft will not work with a constant speed prop. An aerobatic
crankshaft, as used on the AEIO-360 series engines, may be stronger then the
usual hollow crankshaft, but it does work with a constant speed prop, and it
is especially valuable.