MP[_2_]
April 16th 09, 07:28 AM
Thought I'd ask for comments before doing something stupid and irreparable
to our propeller.
We have a Hartzell Q-tip prop on our Glasair. That's the fancy bent over tip
that gets all the jokes about the FAA Inspector who grounded a Cheyenne when
the propellor first came out. (Looks like the prop had a ground strike.)
When we got it, the Q-tip was a hot thing, and we were coming off a Prince
P-tip, which also had a turned under "winglet."
Then Paul Lipps came along and wrote that putting a big hunk of metal out
there on the prop tip is about the stupidest thing one could do, since the
prop tip is where velocity - and therefore, drag - is highest. He wrote
about cutting the tips off a Prince wood prop and getting a phenomenal
improvement in propeller efficiency.
I'm not going to cut off the Q-tip entirely. But I thought I would try a
compromise solution, and cut part of it off. I should link a photo to show
you my markups on the tip, but the plan is to cut the front of the winglet
to put a 60 degree shear on the front, like you see on the Katana wingtips
and on Paul Lipps' Lancair. I will be careful, will sand out the stress
risers, etc. I have a good gram scale to weigh the cutoffs to match, and a
dynamic prop balancer to rebalance after the operation.
It's a homebuilt, so I'm deep into "experimental" mode on this one. Anyone
want to warn me about how I might kill myself doing this? Has anyone done
this before?
Thanks,
Mike Palmer <><
to our propeller.
We have a Hartzell Q-tip prop on our Glasair. That's the fancy bent over tip
that gets all the jokes about the FAA Inspector who grounded a Cheyenne when
the propellor first came out. (Looks like the prop had a ground strike.)
When we got it, the Q-tip was a hot thing, and we were coming off a Prince
P-tip, which also had a turned under "winglet."
Then Paul Lipps came along and wrote that putting a big hunk of metal out
there on the prop tip is about the stupidest thing one could do, since the
prop tip is where velocity - and therefore, drag - is highest. He wrote
about cutting the tips off a Prince wood prop and getting a phenomenal
improvement in propeller efficiency.
I'm not going to cut off the Q-tip entirely. But I thought I would try a
compromise solution, and cut part of it off. I should link a photo to show
you my markups on the tip, but the plan is to cut the front of the winglet
to put a 60 degree shear on the front, like you see on the Katana wingtips
and on Paul Lipps' Lancair. I will be careful, will sand out the stress
risers, etc. I have a good gram scale to weigh the cutoffs to match, and a
dynamic prop balancer to rebalance after the operation.
It's a homebuilt, so I'm deep into "experimental" mode on this one. Anyone
want to warn me about how I might kill myself doing this? Has anyone done
this before?
Thanks,
Mike Palmer <><