A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Home Built
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

"Lippsing" a Q-tip propeller



 
 
Thread Tools Display Modes
  #1  
Old April 16th 09, 07:38 AM posted to rec.aviation.homebuilt
MP[_2_]
external usenet poster
 
Posts: 5
Default "Lippsing" a Q-tip propeller

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


Ads
  #2  
Old April 17th 09, 02:14 AM posted to rec.aviation.homebuilt
Capt. Geoffrey Thorpe
external usenet poster
 
Posts: 790
Default "Lippsing" a Q-tip propeller

"MP" wrote in message
...
Thought I'd ask for comments before doing something stupid and
irreparable
to our propeller.

...
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?


Sure, I'd be happy to warn you.

Has anyone killed themselves after cutting down a prop?

Yup.

Cut down props were popular on the early T-18's - at least until the first
few fatal accidents. When the blade broke due to resonance / fatigue the
engine would part company with the aircraft and the result was typically a
dead pilot / passenger.

Changing the length of the prop changes the resonant frequencies with
unpredictable results.

http://www.t18.net/technical_info.htm#Cutdown

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

  #3  
Old April 22nd 09, 02:52 AM posted to rec.aviation.homebuilt
Charlie[_2_]
external usenet poster
 
Posts: 56
Default "Lippsing" a Q-tip propeller

Joe Brophy wrote:
On Thu, 16 Apr 2009 21:14:38 -0400, "Capt. Geoffrey Thorpe"
The Sea Hawk @See My Sig.com wrote:

"MP" wrote in message
...
Thought I'd ask for comments before doing something stupid and
irreparable
to our propeller.

...
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?

Sure, I'd be happy to warn you.

Has anyone killed themselves after cutting down a prop?

Yup.

Cut down props were popular on the early T-18's - at least until the first
few fatal accidents. When the blade broke due to resonance / fatigue the
engine would part company with the aircraft and the result was typically a
dead pilot / passenger.

Changing the length of the prop changes the resonant frequencies with
unpredictable results.

http://www.t18.net/technical_info.htm#Cutdown



That is why, after you finish with the sawzall, then smooth
it off with a harbor freight angle grinder, make sure the
prop gets a heavy coat of 3m rubberized undercoating. It
dampens out those nasty vibs before they have a chance to
rattle their way through the prop and cause a catastrophic
failure. Good luck, make sure you wear eye protection using
those power tools....regards, Joe.

Are we making a test club with no thrust requirements, or are you just
trolling?
  #4  
Old October 20th 17, 11:17 PM posted to rec.aviation.homebuilt
[email protected]
external usenet poster
 
Posts: 1
Default "Lippsing" a Q-tip propeller

On Thursday, April 16, 2009 at 6:38:17 AM UTC, MP wrote:
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





so how did it work?

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Phrase "landing runway" vs. "cleared to land" Robert M. Gary Piloting 168 February 5th 08 05:32 PM
Phrase "landing runway" vs. "cleared to land" Robert M. Gary Instrument Flight Rules 137 February 5th 08 05:32 PM
Old polish aircraft TS-8 "Bies" ("Bogy") - for sale >pk Aviation Marketplace 0 October 16th 06 07:48 AM


All times are GMT +1. The time now is 03:55 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2004-2018 AviationBanter.
The comments are property of their posters.