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Doug Doty
Joined: 28 Oct 2011
Posts: 33
Location: Madison In
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 Posted: Sun Oct 30, 2011 5:43 pm Post subject: Gary, your honest opinion on ..... |
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The Lopresti nose bowl and related install components, I think it looks like it was well done in terms of installation and craftmanship of the parts but really wonder how good it is for performance and cooling since I bought it installed on the plane and have no base for comparison. I do not have cht data available.
Also I would like to hear from anyone that has back to back data for this conversion would be great to hear your comments.
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_________________
1977 AA5B N28454, Fuel Totalizer, Lopresti Nose, Red Rudder Cap, 4 cyl. egt, stock otherwise. |
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aa5_driver(at)yahoo.com
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| Posted: Sun Oct 30, 2011 6:04 pm Post subject: Gary, your honest opinion on ..... |
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The lopresti kit is an expensive exit ramp with an aestheticly improved nose bowl and a cool looking intake naca duct.
Great marketing, poor service otherwise.
Kevin
Doug Doty <39marinette(at)gmail.com> wrote:
| Quote: |
The Lopresti nose bowl and related install components, I think it looks like it was well done in terms of installation and craftmanship of the parts but really wonder how good it is for performance and cooling since I bought it installed on the plane and have no base for comparison. I do not have cht data available.
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Boats and Planes
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http://forums.matronics.com/viewtopic.php?p=356371#356371
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teamgrumman(at)yahoo.com
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| Posted: Sun Oct 30, 2011 6:08 pm Post subject: Gary, your honest opinion on ..... |
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The truth is, there is little or no difference between the LoPresti nose bowl and a stock nose bowl.
From: Doug Doty <39marinette(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sunday, October 30, 2011 6:43 PM
Subject: TeamGrumman-List: Gary, your honest opinion on .....
--> TeamGrumman-List message posted by: "Doug Doty" <39marinette(at)gmail.com (39marinette(at)gmail.com)>
The Lopresti nose bowl and related install components, I think it looks like it was well done in terms of installation and craftmanship of the parts but really wonder how good it is for performance and cooling since I bought it installed on the plane and have no base for comparison. I do not have cht data available.
--------
Boats and Planes
Read this topic online here:
http://forums.matronics.com/viewt= Archive Search & = &n==
[quote][b]
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bhauskne(at)gmail.com
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| Posted: Sun Oct 30, 2011 6:21 pm Post subject: Gary, your honest opinion on ..... |
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Truth, or just your opinion? The Lopresti is a significantly different
design and similar nosebowls are available for many aircraft.
Seems like Gary is very dismissive of a competing product, so take
that opinion with a dose of skepticism. The Lopresti may not have tha
same characteristics as his cowl, but is it an exaggeration to say
there is little or no difference? Bet Lopresti has a different
perspective.
On 10/30/11, Gary Vogt <teamgrumman(at)yahoo.com> wrote:
| Quote: | The truth is, there is little or no difference between the LoPresti nose
bowl and a stock nose bowl.
________________________________
From: Doug Doty <39marinette(at)gmail.com>
To: teamgrumman-list(at)matronics.com
Sent: Sunday, October 30, 2011 6:43 PM
Subject: Gary, your honest opinion on .....
The Lopresti nose bowl and related install components, I think it looks like
it was well done in terms of installation and craftmanship of the parts but
really wonder how good it is for performance and cooling since I bought it
installed on the plane and have no base for comparison. I do not have cht
data available.
--------
Boats and Planes
Read this topic online here:
http://forums.================
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--
Brian Hausknecht
www.Brianflys.net (Blog)
www.Brianflys.com (Aerial Photo site)
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teamgrumman(at)yahoo.com
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| Posted: Sun Oct 30, 2011 9:16 pm Post subject: Gary, your honest opinion on ..... |
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Except that I have experience with both.
Bob Arnold bought into the LoPresti hype and installed one on his plane because he liked to go fast. He found that his plane was the same speed or slower. Closing thus NACA scoop on the side and taping it over made his plane as fast as it was before. He noticed no change in CHTs.
There is little or no change in cooling. Regardless of what you hear. The way the inlet ramp is formed, unless you really take care installing baffle seals, it doesn't seal off as well as the stock cowling.
There is a slight decrease in cooling drag, but not much. The inlet area is less than the stock cowling. Smaller inlet area means less cooling drag. Unfortunately, it also translates into less pressure drop across the cylinders.
The inclusion of a round inlet, in and of itself, does not reduce drag. The investigation into inlet designs was done at Mississippi State in 1977. They used round because it made the calculations easier. Just because round inlets are in vogue doesn't mean they are designed to work well.
A classic illustration is the cowling on a Mooney Ovation. This was a beautiful inlet. But, it's expensive and difficult to make. Enter the Mooney Acclaim. Same basic cowling, round inlets, but no diverging inlet. The RV-10 inlet is crappy too. Oddly enough, the RV-6 and its metal baffles make a pretty good inlet.
The inlet area on the Jaguar cowling is about one half that of the stock cowling. The difference between the inlets on the Jaguar cowling and the LoPresti nose bowl is that the Jaguar cowling has a diverging inlet; this recovers the pressure by slowing down the air. The pressure drop across the cylinders with the Jaguar cowling is from 1 (slow speed climb) to 5.5 (200 knot dive) inches of water higher than stock. This means I could have still made the inlets smaller. Which means there is still cooling drag I can get rid of. The upside is, during a slow speed climb, there is plenty of cooling air available.
The next time you fly in rain, watch the path the raindrops make on the cowling as the move front to back. Probably the best wind tunnel flow visualization you will ever experience. The rain will flow away from the hinge. As it does, it crosses the crease in the upper cowling at an acute angle. This "flow turning" creates drag.
I could have scabbed in round inlets onto a stock fiberglass cowling. In fact, that was the original plan. One step at a time. But, the more I investigated the drag on the cowling and researched drag reduction from the 30s to current research, the more I realized I needed to do a clean sheet design.
I also flight tested 5 different designs for the bottom of the cowling. The lower cowling on a Piper Malibu may look cool, but it's very draggy.
Gary
Sent from my iPad
On Oct 30, 2011, at 7:18 PM, Brian Hausknecht <bhauskne(at)gmail.com> wrote:
| Quote: |
Truth, or just your opinion? The Lopresti is a significantly different
design and similar nosebowls are available for many aircraft.
Seems like Gary is very dismissive of a competing product, so take
that opinion with a dose of skepticism. The Lopresti may not have tha
same characteristics as his cowl, but is it an exaggeration to say
there is little or no difference? Bet Lopresti has a different
perspective.
On 10/30/11, Gary Vogt <teamgrumman(at)yahoo.com> wrote:
> The truth is, there is little or no difference between the LoPresti nose
> bowl and a stock nose bowl.
>
>
> ________________________________
> From: Doug Doty <39marinette(at)gmail.com>
> To: teamgrumman-list(at)matronics.com
> Sent: Sunday, October 30, 2011 6:43 PM
> Subject: Gary, your honest opinion on .....
>
>
>
> The Lopresti nose bowl and related install components, I think it looks like
> it was well done in terms of installation and craftmanship of the parts but
> really wonder how good it is for performance and cooling since I bought it
> installed on the plane and have no base for comparison. I do not have cht
> data available.
>
> --------
> Boats and Planes
>
>
>
>
> Read this topic online here:
>
> http://forums.================
--
Brian Hausknecht
www.Brianflys.net (Blog)
www.Brianflys.com (Aerial Photo site)
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