Today's Message Index:
----------------------
1. 06:45 AM - Aircraft performance (was Antennas) (Gilles Thesee)
2. 08:22 AM - Re: Aircraft performance (was Antennas) (Kevin Horton)
3. 12:19 PM - Matronics BBS Forums (Matt Dralle)
4. 12:50 PM - hidden attennae (Ernest Christley)
5. 04:29 PM - Re: Aircraft performance (was Antennas) (Gilles Thesee)
6. 07:25 PM - Alternator Field Breaker/Switch (Mark Chamberlain)
7. 08:25 PM - Re: Alternator Field Breaker/Switch (Dale Ensing)
Message 1
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Subject: | Aircraft performance (was Antennas) |
--> AeroElectric-List message posted by: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
Cher George Mc. Jetpilot,
Thank you for replying.
Hope the group won't mind this conversation. After all, the initial
topic was about hiding or not hiding antennas.
> In the US we have large expanse of land and REMOTE
> radio outlets. To get ATC for radar, Flight Watch for
> weather or Flight Service to open / close flight plans,
> a clear powerful radio is so so important. Also we
> have many class B and C air spaces that require a
> good radio.
>
Would 100 NAUTICAL miles at 2000 ft AMSL, or 140 NM when above 5000 ft
fill your requirements ? I'm quite satisfied with that performance.
By the way, in the old continent, towers are more closely spaced than
that, and we seldom have to contact anyone that far. Except for the fun
of testing actual range.
>
>
> This is what my hidden antenna friends heard all the time:
>
> AIRCRAFT CALLING WASHINGTON CENTER YOU ARE
> WEAK AND SCRATCHY,
>
Hmm, maybe they would benefit from the Aeroelcectric List...
By the way, my radio is loud and clear.
>
> ....
>> industry doesn't believe in the existence of drag. Especially
>> in the land of cheap gas and big engines.
>>
> What land and engineers are we talking about, monsieur.
> American engineers? pardonnez-moi
>
Very few light aircraft engineers anywhere are concerned with cooling
drag, internal flow mechanics or drag reduction.
Those who really do their homework design faster airplanes.
>
> Land of cheap gas and big engines? America?
>
Ever bought gas in Europe ? Then you'll understand what I mean ;-)
>
> I would say a long EZ, even with 160HP is way more efficient
> than a MCR 4S
Two of our 5 hangar mates happen to fly Long EZ, and I'm not much
impressed by their performance. And believe me, when taking off or
landing on our less-than 2000 ft grass strip with no wind, they have
their hands full.
> ...I also say a RV-9A is more efficient than
> your MCR 4S. Looking at the RV-9A with 115HP it has 10kt
> faster speed (150kts).
Hey, that's cheat !
You're confusing TOP speed (100% power) and CRUISE speed (75%). The
RV-9A numbers on their website are phony. We all know that 75 % power
speed is 91 % of top speed, that's elementary flight mechanics.
So the RV-9A should either cruise at 136 kt, or peak at 159.
As very few people will minimize their top speed, I'd say that the
little bird tops at 150 kt, and their 75% power cruise is nearer to 90%...
And our bird tops at 155 kt true on 100 hp only.
Oh, and by the way, that's with four on board and 4 hr fuel...
> Not sure what engine you have 80 or
> 115 hp.
>
115 hp takeoff, 100 hp top speed, 75 hp cruise at 140 kt true.
838 lbs empty, 1100-1200 ft/min @ gross weight.
> Want to race my big engined
> RV-7 with O360 190HP?
>
>
Why not race with a two-seater ?
The MCR 01 top speed is 168 kt on 80 hp. If you really want to cling
behind at 80 hp, you better remove those antennas...;-)
Regards,
Gilles
Grenoble, France
http://contrails.free.fr
Message 2
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Subject: | Re: Aircraft performance (was Antennas) |
--> AeroElectric-List message posted by: Kevin Horton <khorton01@rogers.com>
On 22 May 2006, at 09:40, Gilles Thesee wrote:
> --> AeroElectric-List message posted by: Gilles Thesee
> <Gilles.Thesee@ac-grenoble.fr>
>
> Hey, that's cheat !
> You're confusing TOP speed (100% power) and CRUISE speed (75%). The
> RV-9A numbers on their website are phony. We all know that 75 % power
> speed is 91 % of top speed, that's elementary flight mechanics.
> So the RV-9A should either cruise at 136 kt, or peak at 159.
> As very few people will minimize their top speed, I'd say that the
> little bird tops at 150 kt, and their 75% power cruise is nearer to
> 90%...
>
Top speed (100% power) will be achieved at sea level, as the power
will be lower at higher altitudes (assuming a normally aspirated
engine). At sea level, the speed at 75% power should be about 91% of
the speed at 100% power. As you said. But, at a given amount of
power, the speed increases as the altitude increases. So, the best
speed at 75% power will be at the highest altitude at which the
engine will produce this amount of power. That is usually around
8,000 ft for normally aspirated engines, and the speed at that
altitude should only be a few percent slower than the speed with max
power at sea level.
The CAFE Foundation tested Van's 160 hp RV-9A demo aircraft, and they
found that the speed was higher than Van quotes on his web site (193
mph at 8,500 ft density altitude, vs 188 mph claimed by Van's).
Van's claimed 75% cruise number for a 118 hp engine falls pretty much
where you would expect given the difference in power, so I have no
reason to believe that it is phony. I'd be interested in knowing
what test data you have that contradicts the CAFE Foundation results.
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://www.kilohotel.com/rv8
Message 3
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Subject: | Matronics BBS Forums |
--> AeroElectric-List message posted by: Matt Dralle <dralle@matronics.com>
Hello Listers,
I just wanted to send out a reminder to all of the Listers regarding the new-ish
BBS (Bulletin Board System) Forums that are available at Matronics for the Email
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respective email list.
Basically, the BBS Forums give you yet another method of accessing the Matronics
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You'll have to register for a login/password on the BBS Forum to _post_ from the
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page entitled "Register". Click on it and follow the instructions. Site Administrator
approval will be required (to keep spammers out), but I will try to
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If you haven't yet taken a look at the Matronics Email List content over on the
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Thanks for all the great list participation and support; it is greatly appreciated!
Matt Dralle
Matronics Email List Administrator
Message 4
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--> AeroElectric-List message posted by: Ernest Christley <echristley@nc.rr.com>
I'm building a tube and fabric and fiberglass plane, and I'm to the
point of trying to decide where to put the antennae. Keeping drag down
is of upmost importance to me, 'cause I feel that if I wish hard enough
I could be a Reno contender some day 8*)
Well, back to reality....
How about some comments on this person's work in combining the com
antennae with the pitot tube.
http://contrails.free.fr/instruments_ant_sonex.php
--
,|"|"|, Ernest Christley |
----===<{{(oQo)}}>===---- Dyke Delta Builder |
o| d |o www.ernest.isa-geek.org |
Message 5
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Subject: | Re: Aircraft performance (was Antennas) |
--> AeroElectric-List message posted by: Gilles Thesee <Gilles.Thesee@ac-grenoble.fr>
Kevin,
> ... and the speed at that
> altitude should only be a few percent slower than the speed with max
> power at sea level.
>
You're right, we should take air density into account. But at lower
altitudes, the angle of attack is less, and so is drag, so the effect
you describe is somewhat compounded.
I just phoned a buddy aircraft engineer on that matter. A 75% cruise at
only 3 % below top speed still seems rather close, but who knows ?
Please consider that we only talked about the RV-9A because George chose
it for a comparison with our 4-seater. I was not criticizing any of the
RV models.
> The CAFE Foundation tested Van's 160 hp RV-9A demo aircraft, and they
> found that the speed was higher than Van quotes on his web site (193
> mph at 8,500 ft density altitude, vs 188 mph claimed by Van's).
How come ? 2 % more speed means 8 % more power. Please note I'm not
questioning the CAFE ability to test an aircraft.
>
> Van's claimed 75% cruise number for a 118 hp engine falls pretty much
> where you would expect given the difference in power,
118 hp to 160 hp yields a 10-11 % speed gain. And here we have 14 %...
> so I have no
> reason to believe that it is phony.
Please pardon me for questioning those numbers, but at first sight,
they seemed strange to me.
I should have said that I always take published numbers with a grain of
salt.
And there is that tendancy for homebuilts to lose airspeed once they've
crossed the Atlantic ...;-)
> I'd be interested in knowing
> what test data you have that contradicts the CAFE Foundation results.
>
Kevin, all I know is what you just told us, so why would I contradict ?
Hope I didn't ruffle too many feathers.
Best regards,
Gilles Thesee
Grenoble, France
http://contrails.free.fr
Message 6
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Subject: | Alternator Field Breaker/Switch |
--> AeroElectric-List message posted by: "Mark Chamberlain" <mchamberlain@runbox.com>
Hi All,
I'm just in the process of designing the electrical system for my RV-7
and I'm trying to figure out why we need a field switch and/or breaker
for the alternator? I've searched and searched, I can find lot's of
information on how to wire it, but as to the questions "why?", or what
does the "field" wire do ; I can find nothing. I'm guessing it is a very
simple answer and it is just my inexperience showing through.
If someone could enlighten me it would be much appreciated.
Thanks,
Mark
RV-7 - Panel
DO NOT ARCHIVE
Message 7
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Subject: | Re: Alternator Field Breaker/Switch |
--> AeroElectric-List message posted by: "Dale Ensing" <densing@carolina.rr.com>
I'm just in the process of designing the electrical system for my RV-7
and I'm trying to figure out why we need a field switch and/or breaker
for the alternator? I've searched and searched, I can find lot's of
information on how to wire it, but as to the questions "why?", or what
does the "field" wire do ; I can find nothing. I'm guessing it is a very
simple answer and it is just my inexperience showing
In simple terms.........
The field switch supplies current to the alternator field which is required
for the alt. to produce electricity.
The breaker the field switch draws current from is to protect the wiring in
case of an excessive current such as a short.
Dale Ensing
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