Today's Message Index:
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1. 06:47 AM - Re: Back On Line (William L. Paulin)
2. 07:26 AM - Re: Back On Line (n801bh@netzero.com)
3. 08:53 PM - Re: Question for all (Speedy11@aol.com)
Message 1
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Subject: | Re: Back On Line |
Thanks. All the aerobatics I have done has been set the prop & forget it...
so I have been assuming the constant speed choice was only important for xc f
light & cost. And I thought that inverted was better injected even w/o inve
rted fuel & oil systems.
Any idea of the actual first cost &/or maintenance cost differences - carb v
injected & constant speed v fixed pitch ( weight diff too)?
Bill
Sent from my iPhone
On Oct 7, 2010, at 11:13 PM, Kelly McMullen <apilot2@gmail.com> wrote:
> 1. Injected allows finer tuning of the mixture, more balanced power betwee
n cylinders and is less susceptible to any injuction icing if the airbox is p
roperly designed with alternate air. That is an advantage in clouds. Carb is
cheaper, is simpler, uses lower pressure pumps, but needs carb heat plumbed
. However I don't think a carb works as well for inverted flight, but not ce
rtain on that point.
> 2. Constant speed gives better power for climb by maintaining best power r
pm. On the other hand it is heavier and much more expensive than fixed pitch
. You would need to ask RV group as to which is better for aerobatics and fo
r wt and balance on that aircraft.
>
>
> On Thu, Oct 7, 2010 at 7:53 PM, William L. Paulin <wpaulin@usa.net> wrote:
> Question for all:
>
> My son & I are looking for an RV-8. Our mission is split between cross co
untry (must be IFR) & light sport aerobatics. I am a 1500 hr pvt pilot & he
is a Marine F-18 pilot. Our questions are:
>
> 1. What are the advantages & disadvantages of injected vs. Carbureted?
>
> 2. What are the advantages & disadvantages of a constant speed prop.?
>
> Thanks,
>
> Bill
>
> Sent from my iPhone
>
>
>
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Message 2
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Subject: | Re: Back On Line |
There a few things that need to be addressed here.
A 'float' type carb will NOT work inverted. A pressure carb or fuel inje
ction with the correct flop tube in the fuel tank is your only option.
An engine with NO inverted oil system installed and placed up side down
will starve the oil pick up tube instantly and bearing failure will qui
cky follow.
If you are going to do positive G manuevers then the motor does not know
it is up side down and will continue to run.. One small mistake while p
erforming any aerobatic move that lets the plane get into a negative G
inverted position and your motor will not like it.... At ALL...
As for the prop, constant speed is preferred for aerobatics but the fixe
d pitch will work ok too. neither one is a deal breaker. Unlike the flo
at carb and non inverted oil system motor.
IMHO. do not archive
Ben Haas
N801BH
www.haaspowerair.com
---------- Original Message ----------
From: "William L. Paulin" <wpaulin@usa.net>
Subject: Re: Engines-List: Back On Line
Thanks. All the aerobatics I have done has been set the prop & forget i
t...so I have been assuming the constant speed choice was only important
for xc flight & cost. And I thought that inverted was better injected
even w/o inverted fuel & oil systems.
Any idea of the actual first cost &/or maintenance cost differences - ca
rb v injected & constant speed v fixed pitch ( weight diff too)?
Bill
Sent from my iPhone
On Oct 7, 2010, at 11:13 PM, Kelly McMullen <apilot2@gmail.com> wrote:
1. Injected allows finer tuning of the mixture, more balanced power betw
een cylinders and is less susceptible to any injuction icing if the airb
ox is properly designed with alternate air. That is an advantage in clou
ds. Carb is cheaper, is simpler, uses lower pressure pumps, but needs ca
rb heat plumbed. However I don't think a carb works as well for inverted
flight, but not certain on that point.
2. Constant speed gives better power for climb by maintaining best power
rpm. On the other hand it is heavier and much more expensive than fixed
pitch. You would need to ask RV group as to which is better for aerobat
ics and for wt and balance on that aircraft.
On Thu, Oct 7, 2010 at 7:53 PM, William L. Paulin <wpaulin@usa.net> wrot
e:
Question for all:
My son & I are looking for an RV-8. Our mission is split between cross
country (must be IFR) & light sport aerobatics. I am a 1500 hr pvt pilo
t & he is a Marine F-18 pilot. Our questions are:
1. What are the advantages & disadvantages of injected vs. Carbureted?
2. What are the advantages & disadvantages of a constant speed prop.?
Thanks,
Bill
Sent from my iPhone
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Message 3
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Subject: | Re: Question for all |
A Jarhead Target driver! And you're going to let him fly your airplane?
Well, I guess if I let my F-22 driving son fly mine then maybe your RV can
survive, too. But tell him no traps.
I am of the opinion that the RV-8/8A airframe is optimized with the 180 HP
O-360 engine and a fixed pitch cruise prop. I believe the aerodynamics of
the airframe are such that adding power above 180 HP adds very little to
the top end speed and moderately to climb ability. The 180 and fixed pitch
combo keeps the weight low and fuel flow low while providing reasonable
performance.
HOWEVER, having said that, let me say it all depends.
If you are using a turf or short runway, then a CS prop is important - as
is additional HP.
I have a MT 3 blade CS prop on an IO-390 and I am very happy with the
configuration. The extra HP is available if needed and the CS prop climbs like
an angel. I'm airborne solo in about 3-400 feet and I accelerate quickly
to 115KIAS on the deck. A climb to pattern altitude then takes only 6-7
seconds with a final airspeed of about 95KIAS. I can get 184 KIAS at 1000'
MSL, but it drinks a lot of gas. A 2 blade will go a bit faster. Cruise is
about 165 KTAS at about 8.2 GPH. With my engine/prop I'm able to climb to
FL240.
Acro is easy with the 3 blade and 210 HP. A fixed pitch will require
slightly more finesse to avoid overspeeding the engine on downlines.
IFR in the plane is easiest with an autopilot. It is a challenge to hand
fly IFR while shorting charts, tuning radios, making radio calls, etc.
I've found I must be very organized to fly IFR. An autopilot makes the task
much easier. It gives you time to turn your attention to those numerous
things that are required in IFR. Add rain to the mix and an approach to mins
and you'll have your hands full.
The carbureted vs injected arguments by Kelly are on target. I have a ram
air system for my injectior throttle body that will auto revert to filtered
alternate air if the intake should be clogged by ice or a bird.
The RV is ideal for local fun flying and any engine prop combo will work,
but an injected, inverted fuel and oil engine with a CS prop is best.
For CC IFR flying, I'd make sure to have a Primary ADI plus backup, IFR
certified GPS, ILS, and a good autopilot.
I've flown all spins and acro maneuvers except the hammerhead. I've flown
CC from Daytona Beach to Burlington and back. The airplane is fun for all
the above.
Stan Sutterfield
_www.rv-8a.net_ (http://www.rv-8a.net)
Question for all:
My son & I are looking for an RV-8. Our mission is split between cross
coun
try (must be IFR) & light sport aerobatics. I am a 1500 hr pvt pilot & he
i
s a Marine F-18 pilot. Our questions are:
1. What are the advantages & disadvantages of injected vs. Carbureted?
2. What are the advantages & disadvantages of a constant speed prop.?
Thanks,
Bill
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