A question only a newbie would ask

"G.R. Patterson III" wrote in message
...

Stefan wrote:

Effective mufflers already exist, three or
four blade props already exist, and it make a huge difference without
any negative side effect.

They reduce power, add drag, weigh more, and are very expensive. I call
those *big*
negative side effects.

http://www.newpiper.com/FlyerArticleMarch04.pdf

Have a read of the section "Quieter Warrior".

The "expensive" bit is right though!

Paul

"Peter Duniho" wrote in message
...
Muffler-equipped airplanes are not uncommon in Europe. They don't even
look
all that aerodynamic...just a big extension to the exhaust, sticking out
and
along the side of the cowl.

http://www.jodel.com/exhaust.htm

Paul

On Fri, 06 Aug 2004 16:38:31 +0200, Stefan
wrote:

Rick Durden wrote:

requirements such as slower turning, shorter props and more effective
mufflers. It won't be fun.

Why won't it be fun? What's the fun of making a lot of noise and
embarrassing the neighbours? Effective mufflers already exist, three or
four blade props already exist, and it make a huge difference without
any negative side effect.

Where have you been? There are several negatives. Speed and fuel
consumption for a trip. Lower RPM means less HP.

The idea is not to make noise, but to gain efficiency.

The more blades you add to a prop the less efficient. You do gain
climb, but you lose cruise and take more fuel.

Going from a 2 to a three blade prop greatly quieted the Deb, but it
lost about 4 knots top end. Normally you are talking more HP to swing
more blades. Now, if you go to a monster airfoil like the 3-blade
used on Rare Bear, it turns slower and makes less noise than the high
RPM props at the races, but it is *huge*.

BTW, the 3-blade prop on mine weighs 83#. It replaced a 57# 2-blade.
It also cost $8800 exchange and that was nearly 10 years ago.

The most efficient exhaust system is a tuned exhaust and they are not
quite.

One example is http://www.airliners.net/open.file/231156/M/

No, this is an example of a muffler on a light, slow, airplane, not
something with speed. I travel 500 to 1200 miles. I don't want to do
it at 120 MPH. OTOH I normally do it at 5,000 to 8000 feet although
my last trip was over a month ago and most of it was at 2800 due to
the ceilings and airspace.

Just opening the cowl flaps costs me 20 to 30 knots. Imagine what
something like that hanging out would do. Putting the gear down feels
like some one put on the brakes and turned it into a very expensive
Cherokee that burns a lot of gas. With the gear down top speed is
less than the 140 MPH gear down speed. With the gear up and cowl
flaps closed, cruise is a160 knots true at ~6,000 feet.

Currently from Central Michigan I can normally beat the airlines to
Denver or Central Florida as there are no direct flights from here. I
may be slower than they are and I may have to stop once for a potty
break and to top off the tanks, but I'm still usually an hour faster.
That was before 9/11. Now I'm probably 2 hours faster but I've not
had the chance to get to Denver in a couple of years..


Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com




Stefan

On Fri, 06 Aug 2004 17:30:54 +0200, Stefan
wrote:

G.R. Patterson III wrote:

They reduce power, add drag, weigh more

Not really.

Oh yes. As I mentioned in a previous post. I replaced a 2 blade
hartzel on my Deb with a 3-blade hartzel. The 3-blade weighs 83# and
the 2-blade was 57. Stuck that far out in front they certainly make a
difference. It also cost me about 4 knots in cruise.


and are very expensive.

Replacing a perfectly good two blade prop is expensive, yes. But when
the prop must be replaced anyway, or factory installing a four blade
prop instead of a two blader doesn't cost that much more, if you relate

If you don't call $8800 exchange expensive.
Actually you can overhaul a 2 blade for about $5,000 so the 3-blade is
about $3,000 more. Over the life of the prop at 4 knots, the
difference is many thousands of miles.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

it to the total cost of an airplane.

Stefan

On Fri, 06 Aug 2004 16:29:52 GMT, "G.R. Patterson III"
wrote:



Stefan wrote:

But when
the prop must be replaced anyway, or factory installing a four blade
prop instead of a two blader doesn't cost that much more, if you relate
it to the total cost of an airplane.

That's true in many cases. At the rate things are going, I expect to need a new prop
in about 30 years (if I don't get a prop strike before then).

Then we also have to deal with certification issues. The manufacturer has only
certified my aircraft for one prop. I suppose that STCs would be developed pretty
rapidly if 3-blade props were mandated, of course.

And if they were mandated they'd probably run between $1,000 and
$2,000 each plus the cost of the prop and labor.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

George Patterson
In Idaho, tossing a rattlesnake into a crowded room is felony assault.
In Tennessee, it's evangelism.

On Sat, 07 Aug 2004 06:19:25 GMT, "Earl Grieda"
wrote:


"C J Campbell" wrote in message
...


I do think that the demands of airport neighbors that airplanes
make no noise whatsoever are unreasonable. I personally think that
most complaints about noise are really just an excuse to make
airplanes go away. Most people are basically superstitious morons
who have irrational fears of anything that is even a little bit
outside their experience.


Making no noise is probably unreasonable. I suppose even a hot-air ballon
makes some noise ascending. The airport/neighbor noise issue is difficult
to resolve because "resonable/unreasonable" are to subective a term. Would
a requirement that an aircraft on departure sound no louder at 500 feet than

Here reasonable might take on a different meaning. We are located on
the north side of the fair grounds where they hold motorcycle races,
demolition derbies, and rock concerts.

We had a Falcon 900 three engine jet do a max effort take off the
other day. Even scorched all the grass between the end of 06 and the
road. He wasn't nearly as loud as the rock concerts and he was gone
in 30 seconds. There is also a 4 lane express way between the airport
and expensive neighborhood to the south. They often complain about
noise that turns out to be trucks on the express way.

Some day some one isn't going to make it into the short runways and
take out a couple rows of houses all because they wouldn't let the
runways be lengthened. Yet we have 30 to 40,000# jet landing with
just barely legal distance. We have 5 to 7 jets a week, but none
nearly as large as the Falcon 900. Still, if one of those has a
problem on a short runway?

a 2005 factory Accord sound at full power accelerating from stop onto a
freeway with 70 MPH traffic? Not for a new aircraft designed to that
specification, but unreasonable for existing aircraft. But since it will
take decades before existing aircraft disappear noise will be an issue over
and over.

Besides on the highway you have all that heavy traffic with big rigs
and we can not locally regulate the traffic on the interstate.


I doubt if "most complaints about noise" are about making aircraft go away.
They probably are about making the noise go away.

Wait awhile and I think you will see many just want GA to go away.
They don't even want to hear one going over 5,000 feet up.
With our short runway (18/36) lining up with a subdivision off each
end I only use it when I have to, but when I have to I end up only a
few hundred feet high when I go out over the subdivision. I can count
the boards in the picnic tables. Had they not fought the runway
extension I'd be at pattern altitude. Tremendous difference in noise.
They should be happy I spent the $8800 for the 3-blade prop. With the
2-blade the tips were still supersonic when I went out through there.
They tell me the dishes would dance in the cupboards. We still get a
lot of transient aircraft in with big 2-blade props.

The only sympathy I have for the complainers is altruistic. I care
not for them, but I do care how the noise bothering them will affect
my ability to safely fly.

Although I'd not care for the noise myself, were it not for the
negative impact on the airport I'd like to see about 20 AT-6s flying 8
hours a day out of there on the short runway. Not that I'm
vindictive. I try to be a good neighbor, but I still like the thought
of the 20 AT-6s.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


Earl G

Roger Halstead wrote:


Then we also have to deal with certification issues. The manufacturer has only
certified my aircraft for one prop. I suppose that STCs would be developed pretty
rapidly if 3-blade props were mandated, of course.

And if they were mandated they'd probably run between $1,000 and
$2,000 each plus the cost of the prop and labor.

Usually it's the prop manufactoter who lets his props be certified for a
type of plane, because it's him who wants to sell the prop. So you can
buy a fully certified prop. That's how it works in Europe, and how it
would in the US, too, I suppose.

Stefan

Roger Halstead wrote:

Where have you been? There are several negatives. Speed and fuel
consumption for a trip. Lower RPM means less HP.

Why less RPM? Speed maybe, but why more fuel consumtion?

The idea is not to make noise, but to gain efficiency.

Noise is wasted energy. So theoretically, a system with less noise is
more efficient. Practically, there's nothing less efficient than
supersonic props. Mufflers, if well engineered, don't put back pressure
to the engine. The exhaust system is a comlex dynamic oscillation
system, and well tuned mufflers can even enhance the power of an engine.
Rip off the exhaust system from a modern car. You'll be surprised how
much power you loose! (Don't ask me why I know.)

Going from a 2 to a three blade prop greatly quieted the Deb, but it
lost about 4 knots top end.

Agreed, this is a trade off. But, frankly, I think a quiet airplane is
worth 4 knots.

I travel 500 to 1200 miles ... cruise is a160 knots true

Let's see.
1000 nm @ 160 kn gives 6 h 15 min
1000 nm @ 156 kn gives 6 h 24 min

So with the quiet prop, you loose 9 minutes on that 6 hrs trip.

The most efficient exhaust system is a tuned exhaust and they are not
quite.

They can be quite quiet.

No, this is an example of a muffler on a light, slow, airplane, not
something with speed.

Just opening the cowl flaps costs me 20 to 30 knots. Imagine what
something like that hanging out would do.

Agreed. But there are also exhaust systems that fit into a cowling. I
don't have a picture, though.

Stefan

"Roger Halstead" wrote in message
...
On Mon, 9 Aug 2004 15:35:03 +0100, "Paul Sengupta"
http://www.flyflightstar.com/pages/ctphoto.htm

Why the javascript? My firewall takes one look and won't let me go
there.

Um, I don't know. Was just trying to find a photograph.
Takes ages to load on my dial-up connection too...

Do a search for Flight Designs CT and see what you can
find. It's not really a substitute plane for a Deb or Bo though...

Paul

"Roger Halstead" wrote in message
...
Mufflers can not be very effective on big engines without causing back
pressure and a reduction in power.

What you see in Europe is gained more by the reduction in RPM than the
muffler. Lower RPM, less output gasses means the engine is quieter
and it is easier to muffle. It is also developing less HP and in my
opinion creates a safety concern.

Not necessarily. The mufflers/silencers don't. Or don't have to. And
the quietest engines are the Rotax 912s which run at over 5000 rpm.
Of course they don't produce 260hp!

http://www.hliese.de/International/international.html

They do one for the Bo. They claim no performance degredation
and a weight of 2lbs.

"Beech-33, -35 und -36 ( all Versions with Conti. IO-520 )"

Paul