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Cowling / Prop

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dweyant

Well Known Member
Just got the Flyboy Cowling Installation Tool.

Couple questions.

1 - What distance did you use for the flywheel to the front face of the cowling?

2 - What did you use for bolts to attach the Installation Tool to the crank? My prop bolts are captured in the prop, and I don't seem to have any extra of the correct size?

Thanks,

-Dan
 
EZ-Cowl

dweyant said:
Just got the Flyboy Cowling Installation Tool.

Couple questions.

1 - What distance did you use for the flywheel to the front face of the cowling?

2 - What did you use for bolts to attach the Installation Tool to the crank? My prop bolts are captured in the prop, and I don't seem to have any extra of the correct size?

Thanks,

-Dan
Click to expand...

Maybe this will help.
 
How Much Spacing?

The answer is - That is a number that you determine for your particular installation & taste.

That particular item is probably covered in Blake's instructions for using his tool.

But the short version is: From the crankshaft flange (easier to install cowling w/o flywheel in place - just don't forget to allow for its "thickness") to the aft edge of the spinner backing plate, minus allowance for clearance between cowl & spinner, is the number you are looking for.

Given your propeller/spinner combination, there will be a "fixed" number for the distance from the hub face to the aft face of the spinner backing plate - say for example, 3" & the thickness of your flywheel is 1/4".

The space from the crank flange to the back of the spinner is: 3" + 1/4"(flywheel) = 3 1/4". Using that dimension for nose bowl positioning leaves no "gap" between the two, YOU choose what that distance needs to be (1/8" - not enough, 3/4" - might be too much). For our example let's (arbitrarily) pick 7/16". So now the distance from the crank flange to the face of the nose bowl is 3 1/4" - 7/16" = 2 13/16".

So 2 13/16" is the distance (you developed) from the crankshaft flange to the face of the nose bowl, giving 7/16" clearance between cowling & spinner.

YMMV - But you still have to figure out that dimension for yourself.

HFS
 
HFS said:
The answer is - That is a number that you determine for your particular installation & taste.

That particular item is probably covered in Blake's instructions for using his tool.

But the short version is: From the crankshaft flange (easier to install cowling w/o flywheel in place - just don't forget to allow for its "thickness") to the aft edge of the spinner backing plate, minus allowance for clearance between cowl & spinner, is the number you are looking for.

Given your propeller/spinner combination, there will be a "fixed" number for the distance from the hub face to the aft face of the spinner backing plate - say for example, 3" & the thickness of your flywheel is 1/4".

The space from the crank flange to the back of the spinner is: 3" + 1/4"(flywheel) = 3 1/4". Using that dimension for nose bowl positioning leaves no "gap" between the two, YOU choose what that distance needs to be (1/8" - not enough, 3/4" - might be too much). For our example let's (arbitrarily) pick 7/16". So now the distance from the crank flange to the face of the nose bowl is 3 1/4" - 7/16" = 2 13/16".

So 2 13/16" is the distance (you developed) from the crankshaft flange to the face of the nose bowl, giving 7/16" clearance between cowling & spinner.

YMMV - But you still have to figure out that dimension for yourself.

HFS
Click to expand...

Thanks, and that helps quite a bit.

Now my question is, how do I determine the distance from the crank flange to the back of the spinner? I could install the prop and measure, but I'd like to avoid mounting the prop at this time if I can?

I feel like I'm missing something on this, and making it harder than it should be...

Thanks,

-Dan
 
What works for me is an old Hartzell hub (verified to be the same dimensions as the new prop hub). Mount the spinner backplate on the hub, bolt the hub to the engine and you have a perfect jig for fitting the cowl.

Ask around, there my be someone who has a hub laying around that is not airworthy.

Carl
 
To Carl - The OP is using a FlyBoy Accessories cowling installation tool that doesn't use an installed propeller/spinner for the process.

To OP - If you have the propeller/spinner combination in hand, simply measure the distance from the base of the prop hub to the aft side of the spinner/spinner backing plate. If you don't have the propeller/spinner, but know the combo you will be using, you can get that info from the manufacturer.

HFS
 
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