Value of a knot

I am no math weenie, but I read an article once than basically said that
climbing higher always pays off, no matter the distance. In other words,
level cruise was less efficient than a plan where top of climb was the same
as the beginning of the descent.

I can't prove it though, so I will leave it up for debate like you.



"Elwood Dowd" wrote in message
...
Amen brother. Range was one of the main reasons we chose our Beech
Sierra---only 135-ish knots, but 6+ hours aloft make us faster than a
Bonanza on some trips. Not all, but some. Heck, if you have a Mooney
you get higher speed AND more range (but less headroom).

To answer the original question, if I could spend $1000 to get 5 knots I
would do it, but not 1. If I could spend $5000 and be guaranteed 5
knots I would think about it. If I could spend $10,000 on a turbo that
would take me up higher when I need to climb to be safe, I would
seriously think about it, but I wouldn't count on it to give me lots
more speed.

Regarding range---I have found that for our plane at least, a LOT of
fuel savings can be had by flying at 10,500 rather than 6,500. Speed is
very nearly the same while fuel use drops to about 8.9gph, vs. 10.5 at
the lower altitude. This is not a linear relationship and drops off
above about 13,500. I will leave it to the math weenies to tell me
exactly how long I have to fly for a given leg to get a positive return
from amortizing the climb, but on really long legs I always go up high
and it always pays off.

Amen on enjoying the flight.

Personally, speed mods that include upping the GPH are not very interesting
to me for similar reasons.

I mostly fly short trips, and take my time. However, the wife sees the plane
as a way to get places, and so I am concerned about efficiency. Also, the
ability to go more places in a single leg interests me.

I am still thinking a $1000 per knot seems about right to me.


"tony roberts" wrote in message
news:nospam-4FFFDB.23194306092004@shawnews...
My own view - who cares?
I fly because I love to fly - not because I want to get from A to B in X
amount of time. I have friends who go Waaaay faster than me - and they
burn 14gph. I plod along burning 8gph. I love to fly.They get there much
faster and fly a lot less. I doodle along at my 8GPH, and take way
longer than them. There are faster ways of getting there - but that
isn't why I'm flying. I'm flying because I love flying. So how much
would I pay to fly faster? Very little. How much would I pay to get
shorter and safer take-offs from short high density altitude strips?
Lots.

Tony


--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE


In article ,
"Dude" wrote:

I got an idea from a recent thread.

I would like to know what you guys would spend to go a little faster.
This
would seem to be interesting information, and a fun topic.

Please note the present speed of your plane, because 5 knots means a lot
more at 100 than 200.

Personally, It seems to me that a speed mod less than $1,000 a knot is
likely a good deal. I presently fly about 142 in a hurry, and 120 when
I am
not.

I know the people selling the mods often over advertise, but lets assume
we
know the real increase of a given mod from an expert. What's it worth
to
you?




--

Tony Roberts
PP-ASEL
VFR OTT
Night
Cessna 172H C-GICE

"Dude" wrote in message
...
I am no math weenie, but I read an article once than basically said that
climbing higher always pays off, no matter the distance. In other words,
level cruise was less efficient than a plan where top of climb was the
same
as the beginning of the descent.

I can't prove it though, so I will leave it up for debate like you.

I've thought about this when paying tach time for a rental...climbing full
rpm
which isn't too far over the 1 tach hour = 1 clock hour mark but uses lots
of fuel (highish MP, but you don't get to see it on a fixed pitch machine
usually). Then you pull to idle to descend...1 tach hour = maybe 3 clock
hours. So you pay less! :-) Don't suppose it does the engine and fuel bill
much good though.

Paul

Interesting question - answers will be all over the map. But most of
us fly for pleasure. Sometimes I fly 65% instead of 75% just to
prolong the flight. Under these conditions, an extra knot isn't worth
anything.

People who buy speed mods generally just enjoy spending money on their
airplanes; the purported speed gain is only a rationalization.

Ben Jackson wrote:

If you're flying long distances and want to cut the total time, the most
cost effective way is to carry enough fuel that you don't have to stop.
If you can cut a 30 minute fuel stop out of a C-172 flightplan it's like
adding 15kts.

Another way might be to get an instrument rating.

I only have one data point for this, but this spring a fleet of 4
Warriors took a club trip from TTA to IAD. It was a VFR day. The one
flying VFR put 6.1 hours on the hobbes. The three flying IFR all put
5.1 hours on. I was the VFR one. The ADIZ did not slow me down as far
as I can tell. As far as I can tell the penalty was due to:

1. Worse ATC service. Once in the ADIZ and class B, every time I was
switched to a different frequency, I had to wait for several stretches
for there to be a break in the servicing of IFR traffic before I could
even get acknowledged and get a vector. Not to mention how nervous you
can get flying right at the prohibited area (or later, right at the
airport at 3500) on the vector the last guy gave you and the new guy
hasn't acknowledged you for several minutes.

2. More vectoring. While my compatriots were being cleared direct to
Brooke VOR then to IAD, I was getting vectored around the RDU Class C,
and then once in the ADIZ and class B I was vectored all over the place
to basically get me out of the way while the IFR traffic landed, then
they worked me into a gap in the IFR traffic for landing. My first time
on a 13 mile final in a Warrior!

I don't know if this is typical, but assuming an instrutment rating
costs $5-6000 to get working the $/effective knot here might be a pretty
good number. So pilots who fly both IFR and VFR, is that experience
typical? Is better routing and radar service a good enough reason to
get the instrument rating, even if you don't plan to do much hard IFR?

PaulH wrote:
: Interesting question - answers will be all over the map. But most of
: us fly for pleasure. Sometimes I fly 65% instead of 75% just to
: prolong the flight. Under these conditions, an extra knot isn't worth
: anything.

... unless you turn that knot into less GPH. Of course, you'll never make
your money back, but it might help. If you were to add enough speed mods to get the
same speed at 65% you used to get at 75%, it translates into more enjoyment for less
direct cost.

: People who buy speed mods generally just enjoy spending money on their
: airplanes; the purported speed gain is only a rationalization.

Amen to that. If you want a faster airplane, sell what you've got and buy one
that's faster. If you add speed mods, you're not going to get much. Even if you bolt
on a bigger engine, it'll burn more gas, not go appreciably faster. Drag power goes
as the cube of the speed. Changing the drag coefficient (read: speed mods and usually
a few percent at most) changes the required power linearly with speed.

-Cory
--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

Dude wrote:

I am no math weenie, but I read an article once than basically said
that
climbing higher always pays off, no matter the distance. In other
words,
level cruise was less efficient than a plan where top of climb was the
same
as the beginning of the descent.

True for jets, not so for non-turbocharged piston aircraft.

--
Marc J. Zeitlin
http://marc.zeitlin.home.comcast.net/
http://www.cozybuilders.org/
Copyright (c) 2004

In article ,
TTA Cherokee Driver wrote:

Another way might be to get an instrument rating.

1. Worse ATC service [vfr]. Once in the ADIZ and class B, ...

Controllers have to make quick judgements about who they can trust to
execute more complex clearances without deviating. In my experience
several things factor in, including: good radio technique, being on an
IFR flightplan, and flying an airplane that's not typically a trainer.

--
Ben Jackson

http://www.ben.com/

wrote in message news:he7%c.3530$Va5.1196@trnddc01...
On 6-Sep-2004, (Ben Jackson) wrote:


This illustrates why having small tanks in order to obtain high "full fuel"
cabin load is such a stupid idea.

Anybody know of a mod to install a lavatory in place of the back seat in a 172?

-cwk.

On 7-Sep-2004, (C Kingsbury) wrote:

This illustrates why having small tanks in order to obtain high "full
fuel"
cabin load is such a stupid idea.

Anybody know of a mod to install a lavatory in place of the back seat in a
172?

Try:
http://www.sportys.com/acb/showdetl...._ID=297&DID=19

Cheap, too!

--
-Elliott Drucker