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larry(at)macsmachine.com
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 Posted: Sat Jun 23, 2007 3:17 pm Post subject: wheel pants speed |
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*John,
After designing my own wheel pants, replacing the Zenith torpedoes. I
got more of an increase at cruise than
top end. These are larger fairings than what's seen on the XL with 5"
wheels, so you probably would not see that
much a difference. I now fly 17 degree pitch and top out at 133 but
have no data without wheel fairings for this pitch.
(from my journal) In any case you'll be faster than this with or
without fairings in an XL.
June 19* Father's day was a calm and sunny morning. I went to the hangar
and did a thorough preflight inspection, topped off the plane with
87-octane fuel and checked the wheel fairings. I took off from runway
31, climbed 80 mph at 4800 rpm with the propeller set at 16-degrees. The
rudder and elevator inputs seemed a little slippery. I leveled off at
3000 ft to an ambient temperature of 76-degrees. At 4000-rpm the plane
eased past 100 mph, at 4200-rpm, airspeed climbed to 105, at 4450-rpm
airspeed passed 110 and 4700-rpm brought it to 115 mph, and 5100-rpm put
airspeed just over 125, and more importantly, all engine temperatures
stayed within limits. I ran the four main compass headings on the GPS
with these settings and came back to average these. After spending a
little more time in realistically evaluating past performance, the pitot
driven airspeed seems to be within 1 mph or dead accurate with the GPS.
I believe there's not more than 3 mph gained at top end, but there's a
6-mph improvment in mid-range cruise between 4200 to 4800-rpms. In any
case, the plane performed really well, but for what seemed like a faster
approach and longer rollout. To get a better handle on that, the
fairings will stay on until it's time to paint.
Good luck,
Larry McFarland 601HDS at www.macsmachine.com
do not archive
john butterfield wrote:
| Quote: |
hi list
i checked the archives and did not find any real
answer to the questions of speed increases by having
wheel pants.
i actually like to see the wheels on pre-flight. also
be able to put air in the tires without undue trouble,
therefore, has any 601 flyers really noticed an
increase in speed and if so, how much. for my part, a
couple of knots increase in not worth not being able
to really preflight the aircraft landing system.
however, 4 plus would be worth it to me. the extra
couple of knots in a two hour flight is pretty
meaningless, especially if you use gps and plan your
route well, and when sight seeing, the speed is a non
issue.
john butterfield
XL, corvair
torrance, ca
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fderfler(at)gmail.com
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| Posted: Sun Jun 24, 2007 7:27 am Post subject: Wheel pants speed |
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The topic of an increase in speed from wheel pants has been analyzed down to the microscopic level on discussion groups such as the Grumman Gang. With a Grumman, which does not have a steerable nose wheel, the primary benefit of fairings seems to be to keep the nose wheel straight. We 601 drivers don't face that challenge.
Here are some some conclusions I've drawn over the years of reading about and flying with and without wheel pants:
* I note from photo archives of the Reno Air Races that if professional air racers didn't have retractable gear they had pants. I bet they tested and proved their worth.
* Not all wheel pants are created equal. For example, DMA claims their pants (for Grummans) are significantly better than any other design. That debate still rages, but clearly what can be said of one set of pants might not fit into another set of pants.
* They make the airplane look spiffy! I believe that eye-candy is their primary benefit. In my mind, any discussion of pants on a 601 is primarily about cool looks and the extra knots (or not) is the excuse.
* If you have a flat tire on landing, you can litter the runway with expensive fiberglass. And, I had a flat tire on my 3rd landing in my 601. Bad tube or bad installation? One of the other. But, the fact is that everything would have been a lot worse / expensive if I had pants on the 601
* Preflight is much harder. Checking the air / filling with air is much more difficult.
* IF you are not the "mechanic", " certificate holder" etc (depending on the class) and can't take off your own pants, then the annual is more expen$ive by an hour or more.
* They add some weight. In a 601 it's almost always about weight more than speed.
So, in my case I chose to go pantless. Yes, my 601 would look cooler with pants, but the benefits overcome the gains.
Frank Derfler
--See my Blog at http://MostlyFlying.Blogspot.com
--My great gifts for guys at http://www.greatguybooks.com
--My information for pilots at http://www.flyinflorida.com
--My tips for boaters at http://www.keysboater.com
[quote][b]
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pilot4pay
Joined: 01 Jan 2007
Posts: 171
Location: Louisville, KY
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| Posted: Sun Jun 24, 2007 8:09 am Post subject: Wheel pants speed |
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From: owner-zenith-list-server(at)matronics.com [mailto:owner-zenith-list-server(at)matronics.com] On Behalf Of Frank Derfler
Sent: Sunday, June 24, 2007 11:26 AM
To: zenith-list(at)matronics.com
Subject: Wheel pants speed
* IF you are not the "mechanic", " certificate holder" etc (depending on the class) and can't take off your own pants,
I imagine that quite a few other things get expensive as well if you can't take off your own pants! <grin>
So, in my case I chose to go pantless. Yes, my 601 would look cooler with pants, but the benefits overcome the gains.
Frank Derfler
But frank, isn't it a bit chilly in the winter? and in front of the children?!?!
<chuckle> sorry, couldn't resist....
CS
do not archive
[quote][b]
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_________________
Craig Smith
CH640 builder
SN: 0078
"Just think how stupid the average person is,
and then realize that half of them are even stupider!"
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bryanmmartin
Joined: 10 Jan 2006
Posts: 1018
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| Posted: Sun Jun 24, 2007 3:25 pm Post subject: Wheel pants speed |
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On Jun 24, 2007, at 11:26 AM, Frank Derfler wrote:
| Quote: |
* IF you are not the "mechanic", " certificate holder" etc (depending on the class) and can't take off your own pants, then the annual is more expen$ive by an hour or more.
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Even on certificated aircraft, the pilot-owner is allowed to remove the wheel pants on his airplane. He is, in fact, allowed to remove any non-structural items such as inspection panels, cowlings and fairings in order to perform certain types of routine maintenance on his airplane or prepare it for the annual inspection.
On Experimental Amateur Built or E-LSA aircraft, there is no certification of any kind required to remove wheel pants from the airplane or perform maintenance. Certification is only required to perform the annual inspection.
--
Bryan Martin
N61BM, CH 601 XL,
RAM Subaru, Stratus redrive.
do not archive.
[quote][b]
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_________________
--
Bryan Martin
N61BM, CH 601 XL, Stratus Subaru.
do not archive. |
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fderfler(at)gmail.com
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