Today's Message Index:
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1. 09:26 AM - Re: deck angle (taildrags)
2. 10:02 AM - Re: Re: deck angle (Steven Dortch)
3. 01:09 PM - Re: Re: deck angle ((null) raykrause)
4. 02:24 PM - Re: deck angle (taildrags)
5. 02:54 PM - Re: Re: deck angle (Steven Dortch)
6. 08:03 PM - Re: deck angle (taildrags)
7. 08:42 PM - Re: Re: deck angle (Steven Dortch)
Message 1
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Ray; I can't imagine that the larger tires will make that big a difference in cruise
airspeed, especially since my throttle is typically only set about 60% open
in cruise. I run my A75 more like an A65 and the fuel burn reflects that
conservative power setting. I have the power available to overcome the additional
drag.
My empty CG is at roughly 13" aft of datum (wing L.E.) and the main gear axles
are at about 6.8" aft of datum, so heavier tires will move the CG forward by just
a tad. I'll know more once I weigh the new tires and tubes compared to the
old ones.
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power, 72x36 Culver prop
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473403#473403
Message 2
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Oscar, it is unseemly to brag about the high performance of your 75 hp
monster.vs the morning pedestrian A65.
Seriously, is there much difference?
On Oct 7, 2017 11:27 AM, "taildrags" <taildrags@hotmail.com> wrote:
>
> Ray; I can't imagine that the larger tires will make that big a difference
> in cruise airspeed, especially since my throttle is typically only set
> about 60% open in cruise. I run my A75 more like an A65 and the fuel burn
> reflects that conservative power setting. I have the power available to
> overcome the additional drag.
>
> My empty CG is at roughly 13" aft of datum (wing L.E.) and the main gear
> axles are at about 6.8" aft of datum, so heavier tires will move the CG
> forward by just a tad. I'll know more once I weigh the new tires and tubes
> compared to the old ones.
>
> --------
> Oscar Zuniga
> Medford, OR
> Air Camper NX41CC "Scout"
> A75 power, 72x36 Culver prop
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473403#473403
>
>
Message 3
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Oscar,
I'm sure you will see no difference In your plane's performance or W/B. I k
new you had it all figured out.....as our resident aeronautical engineer! I
really appreciate all you writings and calculations regarding all things Pi
etenpol.
Thanks for everything,
Ray Krause
Sent from my iPad
> On Oct 7, 2017, at 10:01 AM, Steven Dortch <steven.d.dortch@gmail.com> wro
te:
>
> Oscar, it is unseemly to brag about the high performance of your 75 hp mon
ster.vs the morning pedestrian A65.
>
> Seriously, is there much difference?
>
>> On Oct 7, 2017 11:27 AM, "taildrags" <taildrags@hotmail.com> wrote:
>>
>> Ray; I can't imagine that the larger tires will make that big a differenc
e in cruise airspeed, especially since my throttle is typically only set abo
ut 60% open in cruise. I run my A75 more like an A65 and the fuel burn refl
ects that conservative power setting. I have the power available to overcom
e the additional drag.
>>
>> My empty CG is at roughly 13" aft of datum (wing L.E.) and the main gear a
xles are at about 6.8" aft of datum, so heavier tires will move the CG forwa
rd by just a tad. I'll know more once I weigh the new tires and tubes compa
red to the old ones.
>>
>> --------
>> Oscar Zuniga
>> Medford, OR
>> Air Camper NX41CC "Scout"
>> A75 power, 72x36 Culver prop
>>
>>
>>
>>
>> Read this topic online here:
>>
>> http://forums.matronics.com/viewtopic.php?p=473403#473403
>>
>>
>>
>>
>>
>>
>> =========================
>> br> enpol-List" rel="noreferrer" target="_blank">http://www.matronics
..com/Navigator?Pietenpol-List
>> =========================
>> FORUMS -
>> eferrer" target="_blank">http://forums.matronics.com
>> =========================
>> WIKI -
>> errer" target="_blank">http://wiki.matronics.com
>> =========================
>> b Site -
>> -Matt Dralle, List Admin.
>> rel="noreferrer" target="_blank">http://www.matronics.com/contributio
n
>> =========================
>>
>>
>>
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Steve; the A75 is basically just an A65 that has some modifications that provide
adidtional lubrication and cooling when the engine is run at higher RPM to put
out more power. The engines have the same bore, stroke, and compression ratio.
The A65 makes its rated power at 2300 RPM and the A75 makes its rated power
by turning up past that to 2600.
Both my A65 and A75 run the Stromberg NAS3-A1 carb with 1-1/4" venturi and #49
main jet. When I was flying with the A65, I never had the throttle firewalled
in cruise either... there was virtually no difference in cruise speed by pushing
the throttle in our out that last about 15% so I ran it where it felt right,
which was 2200-2250. I run the A75 about 2400. Prop selection is what lets
the A75 wind up to a higher RPM than the A65.
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power, 72x36 Culver prop
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473414#473414
Message 5
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Is climb much better? Load hauling?
On Oct 7, 2017 4:25 PM, "taildrags" <taildrags@hotmail.com> wrote:
>
> Steve; the A75 is basically just an A65 that has some modifications that
> provide adidtional lubrication and cooling when the engine is run at higher
> RPM to put out more power. The engines have the same bore, stroke, and
> compression ratio. The A65 makes its rated power at 2300 RPM and the A75
> makes its rated power by turning up past that to 2600.
>
> Both my A65 and A75 run the Stromberg NAS3-A1 carb with 1-1/4" venturi and
> #49 main jet. When I was flying with the A65, I never had the throttle
> firewalled in cruise either... there was virtually no difference in cruise
> speed by pushing the throttle in our out that last about 15% so I ran it
> where it felt right, which was 2200-2250. I run the A75 about 2400. Prop
> selection is what lets the A75 wind up to a higher RPM than the A65.
>
> --------
> Oscar Zuniga
> Medford, OR
> Air Camper NX41CC "Scout"
> A75 power, 72x36 Culver prop
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473414#473414
>
>
Message 6
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Steve; this is Aero 101: there are four basic forces that act on an airplane in
flight: gravity, lift, thrust, and drag. We can't change gravity, so that leaves
us three variables. Of those three, drag is pretty much a characteristic
of our airframe and accessories, but we really don't see a lot of streamlined
Air Campers so drag is going to be proportional to velocity. Most Air Campers
all cruise in a pretty narrow range of airspeeds, so we can almost treat drag
as a constant too. Yes, we can use fairings to reduce intersection drag where
struts meet the fuselage and wings, and we can install wheel pants to reduce
drag from the landing gear and maybe do a little better than a stock airplane.
The rest of it is parasite drag from the wing, plus drag from the brace wires
and the "flat plate" surface area that the airplane presents to the oncoming
air. Bottom line, we can't do too much about drag.
That leaves two variables: lift and thrust. The Pietenpol airfoil is pretty efficient
at producing lift and it's got a lot of surface area, so it can lift quite
a bit of weight at a good rate of climb if you can keep the air moving over
it at a good airspeed. Thrust is what it takes to overcome drag, which increases
airspeed, which increases lift, which overcomes gravity. So thrust is
king, and it's horsepower that produces thrust, so that's our big variable.
The basic powerplant for the Air Camper is a nominal 40HP Ford engine (some say
35HP, so we'll say somewhere in that range but 40 is a nice round number). With
that amount of power, the Air Camper can get two people off the ground with
the airplane at max gross, but it's not going to climb very well. The Ford
A engine has enough excess thrust to overcome the airplane's drag, which keeps
the air moving over the wing at a decent rate, which creates enough lift to get
the airplane and its load off the ground and climbing, which overcomes gravity.
So let's develop a very theoretical situation where we have a 2500 ft long
runway with a fully-loaded Ford A-powered Air Camper taking off at one end.
If it takes off, climbs out, and flies a rectangular traffic pattern that puts
it at traffic pattern altitude of 900 AGL by the time it's abeam the numbers
for power reduction for landing, it will have flown maybe 8000 ft through the
air at 50 MPH, so let's round it off and say the airplane may have taken 2 minutes
to climb the 900 ft to pattern altitude, for a climb rate of 450 ft/min.
The next most common engine in the Air Camper is the A65, which provides (on paper,
at least) about 60% more horsepower than the Ford. Since the Ford is quite
capable of doing the job of lifting a fully-loaded Air Camper off the ground,
a lot of the A65's 25 additional horsepower is available to develop excess
thrust, which provides a better rate of climb with a full load. It won't increase
the climb rate by 60% to 720 ft/min, but let's just say it does. That means
the airplane could climb to pattern altitude in 1.25 minutes, putting it
at pattern altitude when it gets abeam the numbers at the departure end of the
runway (more or less), rather than when abeam the numbers at the approach end.
Just talking hypothetically now, but when I used to fly that kind of a square
pattern flying out of San Geronimo, I may have been able to achieve that on
a good day.
My A75 can produce maybe 80% more power than the Ford, so a lot of its 35 additional
horsepower is available to develop excess thrust to provide a better rate
of climb with a full load. Playing the same theoretical game as with the A65,
let's say the climb rate on my airplane is now 810 ft/min and I can maintain
it all the way to pattern altitude if I fly the airplane at 50MPH. I should
be able to get to pattern altitude in just a little over a minute, which means
I would be at pattern altitude as I turn onto the downwind leg from crosswind.
Pretty optimistic, I may have seen that kind of performance on one or two
cold mornings when everything was perfect, but stay with me now for the rest.
The O-200 and the Corvair can each produce about 100HP... about 150% more power
than the Ford. If I use the same ratio of rates of climb, that would mean that
a Corvair or O-200 powered Air Camper could make a climb rate of 1125 ft/min
in the same scenario and I should be at pattern altitude in 48 seconds, which
would put me at pattern altitude just before I turn onto the crosswind leg on
takeoff. I would have to ask the PietVair pilots out there whether their airplanes
can take off from a 2500 ft strip, climb out at 50 MPH at full gross,
and be at pattern altitude before turning crosswind after leaving the runway departure
end threshold about 1000 feet behind them, but my guess is that they
might.
On a hot day at anything higher than sea level and with little or no headwind,
all of those theoretical numbers are going to sag like a beer belly, and I've
only created these scenarios to provide food for thought.
--------
Oscar Zuniga
Medford, OR
Air Camper NX41CC "Scout"
A75 power, 72x36 Culver prop
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=473423#473423
Message 7
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So Oscar, you really don't know! Ducking and running.
Your discussion makes sense. My experience is with Cessna 150s vs 152s. The
150 has a 100 hp Continental vs the 152 with a 110 hp Lycoming. But I never
could tell a difference in performance.
My other experience is shopping for a Piper Tripacer. The 135hp model was a
marginal 3 placer that doesn't climb well. The 150 hp model flies really
well and hauls 4 people. The 160hp is great.
On Oct 7, 2017 10:05 PM, "taildrags" <taildrags@hotmail.com> wrote:
>
> Steve; this is Aero 101: there are four basic forces that act on an
> airplane in flight: gravity, lift, thrust, and drag. We can't change
> gravity, so that leaves us three variables. Of those three, drag is pretty
> much a characteristic of our airframe and accessories, but we really don't
> see a lot of streamlined Air Campers so drag is going to be proportional to
> velocity. Most Air Campers all cruise in a pretty narrow range of
> airspeeds, so we can almost treat drag as a constant too. Yes, we can use
> fairings to reduce intersection drag where struts meet the fuselage and
> wings, and we can install wheel pants to reduce drag from the landing gear
> and maybe do a little better than a stock airplane. The rest of it is
> parasite drag from the wing, plus drag from the brace wires and the "flat
> plate" surface area that the airplane presents to the oncoming air. Bottom
> line, we can't do too much about drag.
>
> That leaves two variables: lift and thrust. The Pietenpol airfoil is
> pretty efficient at producing lift and it's got a lot of surface area, so
> it can lift quite a bit of weight at a good rate of climb if you can keep
> the air moving over it at a good airspeed. Thrust is what it takes to
> overcome drag, which increases airspeed, which increases lift, which
> overcomes gravity. So thrust is king, and it's horsepower that produces
> thrust, so that's our big variable.
>
> The basic powerplant for the Air Camper is a nominal 40HP Ford engine
> (some say 35HP, so we'll say somewhere in that range but 40 is a nice round
> number). With that amount of power, the Air Camper can get two people off
> the ground with the airplane at max gross, but it's not going to climb very
> well. The Ford A engine has enough excess thrust to overcome the
> airplane's drag, which keeps the air moving over the wing at a decent rate,
> which creates enough lift to get the airplane and its load off the ground
> and climbing, which overcomes gravity. So let's develop a very theoretical
> situation where we have a 2500 ft long runway with a fully-loaded Ford
> A-powered Air Camper taking off at one end. If it takes off, climbs out,
> and flies a rectangular traffic pattern that puts it at traffic pattern
> altitude of 900 AGL by the time it's abeam the numbers for power reduction
> for landing, it will have flown maybe 8000 ft through the air at 50 MPH, so
> let's round it off and say the a!
> irplane may have taken 2 minutes to climb the 900 ft to pattern altitude,
> for a climb rate of 450 ft/min.
>
> The next most common engine in the Air Camper is the A65, which provides
> (on paper, at least) about 60% more horsepower than the Ford. Since the
> Ford is quite capable of doing the job of lifting a fully-loaded Air Camper
> off the ground, a lot of the A65's 25 additional horsepower is available
> to develop excess thrust, which provides a better rate of climb with a full
> load. It won't increase the climb rate by 60% to 720 ft/min, but let's
> just say it does. That means the airplane could climb to pattern altitude
> in 1.25 minutes, putting it at pattern altitude when it gets abeam the
> numbers at the departure end of the runway (more or less), rather than when
> abeam the numbers at the approach end. Just talking hypothetically now,
> but when I used to fly that kind of a square pattern flying out of San
> Geronimo, I may have been able to achieve that on a good day.
>
> My A75 can produce maybe 80% more power than the Ford, so a lot of its 35
> additional horsepower is available to develop excess thrust to provide a
> better rate of climb with a full load. Playing the same theoretical game
> as with the A65, let's say the climb rate on my airplane is now 810 ft/min
> and I can maintain it all the way to pattern altitude if I fly the airplane
> at 50MPH. I should be able to get to pattern altitude in just a little
> over a minute, which means I would be at pattern altitude as I turn onto
> the downwind leg from crosswind. Pretty optimistic, I may have seen that
> kind of performance on one or two cold mornings when everything was
> perfect, but stay with me now for the rest.
>
> The O-200 and the Corvair can each produce about 100HP... about 150% more
> power than the Ford. If I use the same ratio of rates of climb, that would
> mean that a Corvair or O-200 powered Air Camper could make a climb rate of
> 1125 ft/min in the same scenario and I should be at pattern altitude in 48
> seconds, which would put me at pattern altitude just before I turn onto the
> crosswind leg on takeoff. I would have to ask the PietVair pilots out
> there whether their airplanes can take off from a 2500 ft strip, climb out
> at 50 MPH at full gross, and be at pattern altitude before turning
> crosswind after leaving the runway departure end threshold about 1000 feet
> behind them, but my guess is that they might.
>
> On a hot day at anything higher than sea level and with little or no
> headwind, all of those theoretical numbers are going to sag like a beer
> belly, and I've only created these scenarios to provide food for thought.
>
> --------
> Oscar Zuniga
> Medford, OR
> Air Camper NX41CC "Scout"
> A75 power, 72x36 Culver prop
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=473423#473423
>
>
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