I've got a 170A with the original rounded hub spinner. I'm looking for an upgrade to help with aero and cooling. Anybody out there know where I can get a used pointy one that will fit the 8 hole Cont 145hp? I would need the backing plate also.
I've got the prop off right now during an annual and I'm having it re-pitched from 76-50 to 76-48. Anybody know if that's a typical pitch for a 170A for better climb performance? At 500ft MSL, my static runup RPM has only been 2250-2275. I'm hoping for something closer to 2300.
Bob
Pointy spinner for a 170A!
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Later model C-172 kind of "pointy" or the "bullet" style from the C-170/early 172 days? The Bullet ones are available from Spruce/Univair.-
ksaccounts
- Posts: 10
- Joined: Wed Jan 18, 2006 5:25 pm
spinner
Thanks for the reply Doug. I'm looking for the "bullet" type, preferably a used one. I guess "pointy" would not be the best discripton.
Bob
Bob
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GAHorn
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- Joined: Fri Apr 12, 2002 8:45 pm
The spinner is not likely your cooling problem. The probable cause is 1-indicator error, 2-cooling baffle condition/leaks.
With the current prop, a static rpm that low indicates an erroneous/inaccurate tachometer at that rpm. The "standard" climb prop was a 7651.
With the current prop, a static rpm that low indicates an erroneous/inaccurate tachometer at that rpm. The "standard" climb prop was a 7651.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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mit
- Posts: 1067
- Joined: Wed May 01, 2002 1:54 am
and Float prop was 76/49gahorn wrote:The spinner is not likely your cooling problem. The probable cause is 1-indicator error, 2-cooling baffle condition/leaks.
With the current prop, a static rpm that low indicates an erroneous/inaccurate tachometer at that rpm. The "standard" climb prop was a 7651.
Tim
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Dward
- Posts: 96
- Joined: Fri May 26, 2006 4:21 pm
I just bought a 6 bolt unit for my O300D from Al the spinner man at Desert Aircraft. I think he had an ad in TAP. I don't know if I can talk about prices here but it was way cheaper than the other place mentioned and still had the Cessna stickers inside. Also he is nice to deal with.
Dave W
88 cyclo polisher
88 cyclo polisher
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ksaccounts
- Posts: 10
- Joined: Wed Jan 18, 2006 5:25 pm
prop spinner
One of the members with a "bullet" spinner contacted me and I'm going to get it from him. Thanks everyone for the terrific responses.
Bob -- N1320D
Bob -- N1320D
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Dward
- Posts: 96
- Joined: Fri May 26, 2006 4:21 pm
Thanks George. Al the spinner man sold me a complete unit, dome and both bulkheads, for $125.00. Univar wanted $200 and $300 respectively for the bulkheads and $350 for the dome. It should be noted that the Univar parts were new and the dome was aluminum.
Desert Aircraft was very pleasent to deal with and Al took a lot of time trying to help me.
Bob, I'm glad you found what you were looking for.
Desert Aircraft was very pleasent to deal with and Al took a lot of time trying to help me.
Bob, I'm glad you found what you were looking for.
Dave W
88 cyclo polisher
88 cyclo polisher
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GAHorn
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- Joined: Fri Apr 12, 2002 8:45 pm
Re: Pointy spinner for a 170A!
Sorry to be so late in noticing Bob's stated purpose in "upgrade" to a "pointy" spinner...ksaccounts wrote:I've got a 170A with the original rounded hub spinner. I'm looking for an upgrade to help with aero and cooling. ...
Bob
I wouldn't consider a spinner from a later airplane (different model) to be an "upgrade." It's simply a part from a different model aircraft, and would therefore need a basis of approval for installation on a 170. The 170 was test-flown and it's engine was approved with the cooling airflow developed by the original bullet-spinner. While the later 172 may have used a different spinner, it also used a different cowl and different engine baffling system. Therefore the use of a later spinner on an engine utilizing the original cowl/baffles would not likely have been tested for cooling airflow.
Some engine/cowl/baffle combinations are very sensitive to specific spinners and changing that item (or any item in the group) might adversely effect engine cooling, and would require a basis of approval to be considered legal.
(Having posted that msg, ... I'd like to express a personal opinion that I doubt Cessna changed to the pointy spinner for "aero and cooling" anyway. I imagine they did it as a cost-saving move (the pointy spinner is easier/cheaper to make.) The use of a spinner frequently improves engine cooling when compared to non-spinner-equipped aircraft because it calms the "storm" of turbulent air near the prop-hub and directs the relative wind outward toward the cylinder cooling fins. So-called "skull-caps" are likely merely cosmetic in that regard.)
Last edited by GAHorn on Tue Jul 03, 2007 3:50 pm, edited 1 time in total.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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doug8082a
- Posts: 1373
- Joined: Tue Apr 23, 2002 2:06 am
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