Carb heat on Takeoff - Wise?
Dave Egan
I was reading a good article about carb icing in a recent flying rag
and it mentioned a story where someone encountered icing during the
takeoff. If I remember the person ended up burying it due to the lack
of altitude at the time.
Being a new pilot and having only heard about icing worries during
landing, it raised my senses about this condition. Is it normal for
folks to pull on carb-heat during takeoff as well if conditions
warrant it? I've only been taught to pull it on during landing or if
I notice it while flying. Having it happen during take-off could be
disasterous.
--
David Egan Dave.Egan@texoma!net (change the ! to a .)
Peter Gottlieb
Flavius Silva wrote in message <68eq6c$b...@bgtnsc02.worldnet.att.net>...
>
>Carb Heat Reduces Power, not good at takeoff.
>
Too simplistic.
Before takeoff, if I suspected strong icing conditions, I wouldn't go.
If I ran into a problem like engine roughness, loss of power, etc
on the roll, I would treat it like it was... if I could abort the takeoff
I would; if it's too late for that and I'm up too far to get back down
to the runway area, it's the old emergency checklist drilled into
my head: fly the plane, set up for max glide, figure out where to
put down and head there, then carb heat, check fuel selector,
mags, mixture, etc.
On the other hand, a lightly loaded small plane with a very long
runway and no obstacles, sheesh, you can be 500 AGL before
you reach the runway end, so you could probably get away with
the carb heat. I wouldn't use it though, I just wouldn't go if I
really thought that strongly that I needed it to make it...
Flavius Silva
Carb Heat Reduces Power, not good at takeoff.
John - N8086N
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Chris Patten
In article <68eq6c$b...@bgtnsc02.worldnet.att.net>, postm...@0.0.0.0
(Flavius Silva) wrote:
>> Carb Heat Reduces Power, not good at takeoff.
>>
>> John - N8086N
Engine cutoff during takeoff reduces performance. Not good at takeoff.
What's with all the inane comments anyhow, Flavius?
___________________________
delete the word "SPAM" in
the above address to reply
Flavius Silva
In article <pattenc-3112...@ts4-01.ott.istar.ca>, pat...@SPAMmailexcite.com (Chris Patten) wrote:
>What's with all the inane comments anyhow, Flavius?
What are you refering to?
Flavius Silva
In article <68f441$m...@snews1.zippo.com>, "Peter Gottlieb" <xpeter_...@msn.com> wrote:
>Flavius Silva wrote in message <68eq6c$b...@bgtnsc02.worldnet.att.net>...
>>
>>
>
>
>
>Before takeoff, if I suspected strong icing conditions, I wouldn't go.
>
>If I ran into a problem like engine roughness, loss of power, etc
>on the roll, I would treat it like it was... if I could abort the takeoff
>I would; if it's too late for that and I'm up too far to get back down
>to the runway area, it's the old emergency checklist drilled into
>my head: fly the plane, set up for max glide, figure out where to
>put down and head there, then carb heat, check fuel selector,
>mags, mixture, etc.
>
>On the other hand, a lightly loaded small plane with a very long
>runway and no obstacles, sheesh, you can be 500 AGL before
>you reach the runway end, so you could probably get away with
>the carb heat. I wouldn't use it though, I just wouldn't go if I
>really thought that strongly that I needed it to make it...
Carburator icing is most likely to occur in the temperature range 14-70F. If
you don't fly in conditions suitable for carb-ice then you would get in very
little flying in most of the world. The conditions suitable for carburator ice
are significantly different than that for structural icing.
If your aircraft has an engine with a carburator you should have run the
carb-heat during the run-up anyhow. If your engine ran during the taxi to the
run-up pad, you ran carb-heat and made sure that the carb was clear, then your
carburator iced over on takeoff you would have encountered some strange
atmospheric conditions.
The bottom line is check your POH. If it says to take off using carb-heat then
do it. If not then don't do it. I would be very surprised to find a POH that
had a takeoff procedure that used carb-heat. The takeoff performance charts
are based upon full takeup power. If you have the carb-heat on then you do not
have full power.
Bob Noel
In article <68fh7p$q...@bgtnsc02.worldnet.att.net>, postm...@0.0.0.0
(Flavius Silva) wrote:
[snip]
>
> The bottom line is check your POH. If it says to take off using
carb-heat then
> do it. If not then don't do it. I would be very surprised to find a POH that
> had a takeoff procedure that used carb-heat. The takeoff performance charts
> are based upon full takeup power. If you have the carb-heat on then you
do not
> have full power.
furthermore, some engines can be damaged by prolonged operations
at full power (er...throttle) with carb heat on.
--
Bob
(I think people can figure out how to email me...)
(replace ihatessppaamm with my name (rnoel) and mediaone with hw1)
Q Salt
> Carburator icing is most likely to occur in the temperature range 14-70F.
If
> you don't fly in conditions suitable for carb-ice then you would get in
very
> little flying in most of the world. The conditions suitable for
carburator ice
> are significantly different than that for structural icing.
>
> If your aircraft has an engine with a carburator you should have run the
> carb-heat during the run-up anyhow. If your engine ran during the taxi to
the
> run-up pad, you ran carb-heat and made sure that the carb was clear, then
your
> carburator iced over on takeoff you would have encountered some strange
> atmospheric conditions.
>
> The bottom line is check your POH.
Well put and entirely accurate.
My flight manual say carb heat "on" for all takeoffs, believe it or not.
In some airplanes, running full carbheat at full power can cause detonation
and this is reflected in the POH for those types (Can`t think of one
offhand but there are a few)
In any case, sometimes using carbheat for taxi is a necessary evil. Better
to get a few grass clippings blown through your engine than to lose power
on takeoff because you`ve got carb ice. With Continentals this is sometimes
necessary, I find.
Q
Gaylen Lerohl
<big snip>
>The bottom line is check your POH. If it says to take off using carb-heat
then
>do it. If not then don't do it. I would be very surprised to find a POH
that
>had a takeoff procedure that used carb-heat. The takeoff performance charts
>are based upon full takeup power. If you have the carb-heat on then you do
not
>have full power.
I once owned a 1946 Luscombe 8A with a 65 Cont engine. The 8A was
placarded requiring carb heat on takeoff. The story was that when
the airplane had nearly completed certification, it was discovered
that at times the engine would fail from fuel starvation at full power
due to an undersized fuel line to the carburator. The cheap fix was
to reduce take off power by requiriing carb heat on takeoff.
Gaylen "I'm grateful to bureaucrats who keep us safe" Lerohl
kktaylor
Dave Egan wrote:
>
> I was reading a good article about carb icing in a recent flying rag
> and it mentioned a story where someone encountered icing during the
> takeoff. If I remember the person ended up burying it due to the lack
> of altitude at the time.
>
> Being a new pilot and having only heard about icing worries during
> landing, it raised my senses about this condition. Is it normal for
> folks to pull on carb-heat during takeoff as well if conditions
> warrant it? I've only been taught to pull it on during landing or if
> I notice it while flying. Having it happen during take-off could be
> disasterous.
> David Egan Dave.Egan@texoma!net (change the ! to a .)
It's not a bad idea at all to apply carb heat for a short while before
you roll out for take-off if you have been idling during conditions
favorable to carb ice formation. When I do it,I don't remove my hand
from the carb heat knob untill I push it in so as not to forget to close
it. It would not be necessary to apply carb heat with full power on
take-off.
Kelly Taylor
Taylor Aviation
Emmett,Idaho
Peter Gottlieb
Flavius Silva wrote in message <68fh7p$q...@bgtnsc02.worldnet.att.net>...
>
>Carburator icing is most likely to occur in the temperature range 14-70F.
If
>you don't fly in conditions suitable for carb-ice then you would get in
very
>little flying in most of the world.
I meant visible moisture and/or high humidity, not just that carb icing is
*possible*.
>If your aircraft has an engine with a carburator you should have run the
>carb-heat during the run-up anyhow.
Of course, both as a check of functionality and to see if there is any ice
present.
>The bottom line is check your POH. If it says to take off using carb-heat
then
>do it. If not then don't do it. I would be very surprised to find a POH
that
>had a takeoff procedure that used carb-heat.
In the plane I fly, carb heat should be off. I've never tried a takeoff
with it on,
although most of the time you probably wouldn't notice the difference. I
have
heard of some planes where the carb heat should be on for takeoff, though.
Tom Elam
On Wed, 31 Dec 1997 23:14:00 GMT, degan@texoma!net (Dave Egan) wrote:
>I was reading a good article about carb icing in a recent flying rag
>and it mentioned a story where someone encountered icing during the
>takeoff. If I remember the person ended up burying it due to the lack
>of altitude at the time.
>
>Being a new pilot and having only heard about icing worries during
>landing, it raised my senses about this condition. Is it normal for
>folks to pull on carb-heat during takeoff as well if conditions
>warrant it? I've only been taught to pull it on during landing or if
>I notice it while flying. Having it happen during take-off could be
>disasterous.
If the carb is going to ice up it will likely do it on the taxi out. You will
find out about the icing when you check out the carb heat during the runup. I
once had a 150 almost quit during the runup after a 5 minute taxi out on a cool
humid morning. I used carb heat on the takeoff.
---------------------------------------------
Tom Elam
The universe is not only stranger than we imagine,
it is stranger than we CAN imagine.
Richard L. Watson
I am not recommending carb heat on for takeoff, but I will note that at a
low altitude airport, the engine produces much more power with carb heat on
than it does at a high altitude, hot airport with carb heat off. I know of
at least one take-off crash that probably was due to icing in the carb.
--
Richard
Visit our Caribbean Oceanfront Vacation Rental Home
http://swiftsite.com/RoatanHome
kktaylor <kkta...@micron.net> wrote in article
<34ABE5...@micron.net>...
> Dave Egan wrote:
> >
> > I was reading a good article about carb icing in a recent flying rag
> > and it mentioned a story where someone encountered icing during the
> > takeoff. If I remember the person ended up burying it due to the lack
> > of altitude at the time.
> >
> > Being a new pilot and having only heard about icing worries during
> > landing, it raised my senses about this condition. Is it normal for
> > folks to pull on carb-heat during takeoff as well if conditions
> > warrant it? I've only been taught to pull it on during landing or if
> > I notice it while flying. Having it happen during take-off could be
> > disasterous.
Andrew Boyd
Dave Egan <degan@texoma!net> wrote:
> encountered icing during the takeoff ...
>
> Is it normal for folks to pull on carb-heat during takeoff
No, for two reasons: loss of power, and possible detonation.
Check your a/c's POH.
What can you safely do to avoid carb icing on takeoff? Esp
on the first takeoff of the day, when the engine is coldest?
Two things come to mind:
#1) Lean the mixture for takeoff. We don't often do this back
east, at our low density altitudes, but leaning creates heat. As
long as you can do it safely, without causing detonation, the extra
heat the lean mixture causes will help avoid carb ice. See your
POH on the procedure for leaning the mixture for takeoff.
#2) Just before takeoff, when you line up on the runway,
do a mini-runup: 1500 rpm and full carb heat for 10 long
seconds. Then, carb heat cold, and advance the throttle
the rest of the way. If you do this, you *know* that you
didn't have carb ice at the start of the takeoff.
FYI: It's possible to ice up a carb in a full power climb
[more likely in a continental than a lyc]. Happened to
me the other day. That's why I lean the mixture for
takeoff :>
I hate carburetors. Wretched things.
--
ab...@igs.net ATP
JN
A little equation for consideration:
Low altitude + Full power + Carb heat = Possible detonation + engine damage
See your A/C manual for additional information. It seems to me that many of
the
questions asked in NGs would be answered if people would RTFM. ;)
-Jan
George R Patterson
Only been flying relatively new aircraft, haven't you. You will find
nothing in the POH for most aircraft if the plane is more than about 20
years old, or if the plane was made by one of the smaller manufacturers.
The POH for my '69 Cessna didn't have anything, as I recall. The manual
for my '95 Maule doesn't have a word about carb heat.
The Lycoming engine manual for the Maule *does* have a few words (very
few). It simply says to use carb heat "as necessary". Most FBOs don't
keep the engine manuals with the aircraft.
Don't generalize from specific experience.
George Patterson, N3162Q.
Mike Brown
Peter Gottlieb wrote:
> >If your aircraft has an engine with a carburator you should have run
> the
> >carb-heat during the run-up anyhow.
>
> Of course, both as a check of functionality and to see if there is any
> ice
> present.
Yes, but be very careful how you do the check. Most checklists and POH
I've seen say to check that there is an (x) RPM drop on application of
carb heat, which is necessary, but not sufficient.
Leave the heat on for a few seconds and watch the RPM. If it remains
stable, great. If it drops initially, then rises - you acquired carb ice
during taxi and just melted it out. If you just pull the carb heat on,
see the drop, and push it off without waiting, you've not given the heat
time to work, and you could take off with carb ice.
It happened to me once, and it was an eye-opener. The engine began to
run rough right after takeoff, while I was climbing out, too late to
abort. I applied heat, and the engine smoothed out in a short while.
Ever since, I've applied heat after taxi, before takeoff, and waited to
see if there was a rise in RPM. Never had the problem since.
Mike Brown
Cessna 150 N4579U
John R. Johnson
On 3 Jan 1998, JN wrote:
>
> A little equation for consideration:
>
> Low altitude + Full power + Carb heat = Possible detonation + engine damage
>
> See your A/C manual for additional information. It seems to me that many of
> the
> questions asked in NGs would be answered if people would RTFM. ;)
>
> -Jan
>
What manual Jan. I have owned many aircraft over the years but I have
never seen one with a manual that gave instructions for using carb heat,
other than "as required." Perhaps you should check a little farthur.
John
Ron Natalie
Mike Brown wrote:
>
> Leave the heat on for a few seconds and watch the RPM. If it remains
> stable, great. If it drops initially, then rises - you acquired carb
> ice during taxi and just melted it out.
Agreed. Even the less ice prone O-320 in the 172 I've flown
regularly and my Navion will ice up when the engine is cold
and the conditions are right (I humid 50 degree morning is
typical).
James M. Knox
In article <Pine.SOL.3.91.980105114307.28384I-100000@reliant>,
"John R. Johnson" <jo...@siu.edu> wrote:
>> See your A/C manual for additional information. It seems to me
that many of
>> the
>> questions asked in NGs would be answered if people would RTFM. ;)
>>
>> -Jan
>>
>
>What manual Jan. I have owned many aircraft over the years but I
have
>never seen one with a manual that gave instructions for using carb
heat,
>other than "as required." Perhaps you should check a little
farthur.
Actually, quite a few Cessna manuals list carb heat ON for landing.
It depends on the engine installation arrangement.
Piper manuals usually only say "as required" because most Piper
installations are not nearly as succeptible to carb icing. However,
in recent years and because of our rather litiguous society, Piper
has issued several SB letters amending this to "suggest" carb heat
ON for landing.
jmk
John R. Johnson
On Tue, 6 Jan 1998, James M. Knox wrote:
> Actually, quite a few Cessna manuals list carb heat ON for landing.
> It depends on the engine installation arrangement.
>
Yes, some Cessna manuals list carb heat ON for landing. I don't recall
any that have anything to say about carb heat on TAKEOFF, either pro or
con. Many Cessnas don't have manuals. I have only seen manuals for
relatively recent Cessnas. ( ie: most of the nn2 series and some of
the twins )
> Piper manuals usually only say "as required" because most Piper
> installations are not nearly as succeptible to carb icing. However,
> in recent years and because of our rather litiguous society, Piper
> has issued several SB letters amending this to "suggest" carb heat
> ON for landing.
>
Once again, only the relatively recent Pipers have manuals. Those also
don't say anything about carb heat on takeoff. Most of the Pipers I have
flown don't say anything and are certainly as susceptible to carb icing
as anything else with a Continental engine. The later Pipers, with the
Lycoming engines ( after about 1948 ) were somewhat less susceptible to
icing because the Lycoming flat four engine runs the induction through
the oil sump and uses the "heat of vaporization" of the fuel to help
cool the oil. The Continentals do not do that, and are a little more
likely to see carb ice as a result.
In any case, very few "manuals" say anything at all about "carb heat" on
takeoff. If carb heat on takeoff on a damp day when carb ice during
taxi was a problem can cause detonation and engine damage you are most
likely using the wrong fuel in your engine.
John
John R. Johnson
And on those mornings some carb heat on takeoff MAY be wise. Then again,
it may NOT. First, carb ice is MUCH more likely to occur when the throttle
is closed than when it is wide open. Also, the engine is producing a LOT
more heat at full power than it does when taxiing. These factors do
combine to make carb ice on takeoff unlikely. However, it DOES occur.
I would suggest that carb heat on takeoff could be useful on days with
visible humidity and temperatures such that the icing may occur even
without the restriction of the closed throttle plate.
Factors that might suggest you leave the carb heat OFF even under those
conditions would be a short runway requireing a maximum effort takeoff
to get safely away. Of course, carb ice in that situation is even more
dangerous. Clearly some judgement is required and I will not presume
to tell you how to call it.
I think I can safely say that the added heat from the carb heat should
NOT cause heating to the point where detonation is a problem on any day
when it is cool and damp enough to make it necessary. It could cause
a problem on a 110 degree day, but then carb ice should not be a concern
either. There is a significant safety zone built into aircraft engines
before the detonation threshold because it is almost impossible to
detect detonation before major damage occurs. MOdern 100LL and an
older airplane should put you pretty far from detonation, even on a hot
day at full power. However, that safety zone may NOT be there is you
are using discount 80/87 unleaded auto fuel.
John
Jim Wolper
John R. Johnson wrote:
> I think I can safely say that the added heat from the carb heat should
> NOT cause heating to the point where detonation is a problem on any day
> when it is cool and damp enough to make it necessary. It could cause
> a problem on a 110 degree day, but then carb ice should not be a concern
> either. There is a significant safety zone built into aircraft engines
> before the detonation threshold because it is almost impossible to
> detect detonation before major damage occurs. MOdern 100LL and an
> older airplane should put you pretty far from detonation, even on a hot
> day at full power. However, that safety zone may NOT be there is you
> are using discount 80/87 unleaded auto fuel.
>
> John
I have never run into this kind of information...can you suggest a source
for more reading? Thanks.
Jim Wolper ATP/CFI/PhD
Dave Katz
I've had carb ice prior to takeoff in my 172 twice in the last three
days out here in coastal CA. I make a habit of leaving the carb heat
on for 15 or 20 seconds during the runup just to make sure, and if I
end up sitting on the ground waiting for a hole in the traffic before
taking off, I'll give it another blast while taxiing into position.
The first time I had this happen was early in my solo period in a 150.
Best time possible to get carb ice (while on the ground) but it scared
me enough so that I taxiied back to the club and sat there for awhile
until I worked up enough confidence to actually go fly. Now I just
honor it as a good, safe reminder of what can happen in the air.
Mike Brown <br...@bpmlegal.com> writes:
> Yes, but be very careful how you do the check. Most checklists and POH
> I've seen say to check that there is an (x) RPM drop on application of
> carb heat, which is necessary, but not sufficient.
>
> Leave the heat on for a few seconds and watch the RPM. If it remains
> stable, great. If it drops initially, then rises - you acquired carb ice
John R. Johnson
Jim,
My source was pretty well scattered through my five year program in
aeronautical engineering at the University of Minnesota back in the
fifties. We had an excellent engines lab there. You can go through
the engine operation manuals for various aircraft engines, and knowing
the manifold pressure/RPM conbinations they allow for the fuel they
recommended you can make a pretty good windage guess at the detonation
margin they are building into the operation. That it works indicates
that you rarely see detonation damage in an engine unless a fuel
injector clogged or something that radically altered the operating
conditions in the cylinder.
John
Steve Pick
I think maybe you got the right idea first time there Dave.
Perhaps if you see carb ice during taxi, and the engine is not hot yet then
maybe a good idea is not to fly...?
As they say, it's better to be down here wishing you were up there than up
there wishing you were down here.
Dave Katz wrote in message <6xiurxp...@cirrus.juniper.net>...
Hilton Goldstein
Richard L. Watson wrote:
>
> I am not recommending carb heat on for takeoff, but I will note that at a
> low altitude airport, the engine produces much more power with carb heat on
> than it does at a high altitude, hot airport with carb heat off. I know of
> at least one take-off crash that probably was due to icing in the carb.
I've seen several as a result of carb-icing and the NTSB said something
like: "Carb heat was in the OFF position" - as if the pilot had erred.
Can't win 'em all! :(
Hilton
--
Hilton Goldstein.............................hilton@sgi.com
650-933-5254 (phone).....................(fax) 650-390-6159
M/S 1L-945, 2011 N. Shoreline Blvd, Mountain View, CA 94043
http://reality.sgi.com/hilton
Next in the list of ironies: Found missing
Rod Farlee
"JN" <nord...@THISAWAY.dlc.fi> writes:
>A little equation for consideration:
>Low altitude + Full power + Carb heat = Possible detonation + engine damage
>the questions asked in NGs would be answered if people would RTFM. ;)
Anyone with an EGT (exhaust gas temperature) gauge knows this is false.
1) note EGT
2) apply carb heat
3) note EGT is now much lower.
Carb heat lowers the intake air density. But the fuel flow is unchanged.
The mixture is richer, and the detonation margin has increased.
I have seen no engine or airplane manual which mentions detonation.
This is apparently because there is nothing a pilot can do to cause
detonation if the correct grade of fuel is used.
- Rod Farlee
Jerry Bransford
I'm not real experienced with constant-speed propellers (only 20-25
hours), Rod, but can't improper use of the propeller speed control cause
detonation? Kind of like accelerating in too high of a gear in a car
can cause it to detonate/ping...
Jerry
--
Jerry Bransford
To send me email, remove "junkmail" from my email address.
PP-ASEL, C.A.P., KC6TAY
The Zen hotdog... make me one with everything!
Keith Arnold
On 3 Jan 1998 11:18:48 GMT, "JN" <nord...@THISAWAY.dlc.fi> wrote:
>
>A little equation for consideration:
>
>Low altitude + Full power + Carb heat = Possible detonation + engine damage
>
>See your A/C manual for additional information. It seems to me that many of
>the
>questions asked in NGs would be answered if people would RTFM. ;)
>
>-Jan
>
======>
Would the engine quiting because of ice cause any damage to it? :-)
ô¿ô - Keith - 182L/STOL N3431R - Chino, California
N33° 58' 46" W117° 38' 41"
Keith Arnold
On 3 Jan 1998 03:29:13 GMT, "Andrew Boyd" <ab...@igs.net> wrote:
>Dave Egan <degan@texoma!net> wrote:
>
>> encountered icing during the takeoff ...
>>
>> Is it normal for folks to pull on carb-heat during takeoff
>
>No, for two reasons: loss of power, and possible detonation.
>Check your a/c's POH.
>
========>
Some how I always that adding carborator heat enrichend the mixture.
Will this cause detonation? My POH doesn't say much about it, anyway.
ôżô - Keith - 182L/STOL N3431R - Chino, California
Rod Farlee
Jerry Bransford <jer...@junkmailcts.com> writes:
>I'm not real experienced with constant-speed propellers (only 20-25 hours),
>Rod, but can't improper use of the propeller speed control cause detonation?
>Kind of like accelerating in too high of a gear in a car can cause it to
>detonate/ping...
Perhaps so. The scenario is shoving the throttle in while the prop control
is pulled out (missed approach/go-around), contrary to the operating
procedures in the AFM or POH.
The engine operating manual power curves show a line labelled "limiting
manifold pressure for continuous operation". On the 180 hp Lycoming
O-360, it is 5" oversquare. This is also about what fixed pitch props run
at during takeoff and climb at sea level (29" at 2400 rpm). This limit applies
to the original fuel, 91/96 octane avgas. The same engine (same pistons,
same 8.5:1 compression ratio) can be turbocharged, run on 100LL, and
is then limited to 9" oversquare.
The cruise settings listed in the AFM or POH are more conservative
(mine stops at 3" oversquare).
So if you're burning the fuel specified for the engine, it is difficult to
cause
detonation. If you're burning a higher octane fuel, it is very difficult. If
you're burning a lower octane fuel, it is possible (remember the 1994
Chevron incident when avgas was contaminated with Jet-A).
- Rod Farlee
Rick Macklem
Rod Farlee (rodf...@aol.com) wrote:
[stuff deleted..]
: Carb heat lowers the intake air density. But the fuel flow is unchanged.
: The mixture is richer, and the detonation margin has increased.
: I have seen no engine or airplane manual which mentions detonation.
: This is apparently because there is nothing a pilot can do to cause
: detonation if the correct grade of fuel is used.
: - Rod Farlee
The standard ground school manual in Canada (called From the Ground Up)
mentions the possibility of carb heat causing detonation when heat is
applied at above 75% power. Unfortunately it doesn't say why.
So, did the authors know what they were talking about, or just repeating
an "old wives..", or should that be "old pilot's tale"?
Have fun flying, rick
Keith Arnold
>I'm not real experienced with constant-speed propellers (only 20-25
>hours), Rod, but can't improper use of the propeller speed control cause
>detonation? Kind of like accelerating in too high of a gear in a car
>can cause it to detonate/ping...
>
>Jerry
========>
Is ping and detonation the same thing??
ô¿ô - Keith - 182L/STOL N3431R - Chino, California
MTSP
There have been conditions when carb heat was needed on takeoff due to severe
icing conditions. On those occassions we always leaned the mixture after
pulling carb heat to regain some of the lost power. I agree that carb heat will
not cause detonation
Keith Arnold
======>
Absolutly right!!!!
Bob Gardner
Follow the procedure in the approved flight manual. In over thirty years
I have flown *one* airplane that permitted carb heat on takeoff--I think
it was a Luscombe, but it has been a long time ago. It was an old-time
airplane, I can tell you that.
Once you push the throttle in for takeoff power you do not need carb
heat--the engine is producing more than enough heat to keep everything
toasty. It's hard to imagine doing anything to reduce engine power at a
time as critical as the takeoff roll.
Bob Gardner
Ron Clarkson
Keith Arnold wrote:
>
> On 25 Jan 1998 16:11:08 GMT, mt...@aol.com (MTSP) wrote:
>
> >There have been conditions when carb heat was needed on takeoff due to severe
> >icing conditions. On those occassions we always leaned the mixture after
> >pulling carb heat to regain some of the lost power. I agree that carb heat will
> >not cause detonation
> Absolutly right!!!!
>
> ô¿ô - Keith - 182L/STOL N3431R - Chino, California
> N33° 58' 46" W117° 38' 41"
Certainly Carb heat may not cause detonation!
When your preparing for take off, and concerned about detonation OR the
fact that there may be carb icing, lining up for take-off should be a
decision that is best postponed.
Knowing of course that Carb Ice can accumulate in conditions where you
have above freezing temps. If you suspect carb icing, then you should
ensure engine is warm, and any "suspected" carb ice has been ingested,
during your run-up or pretake-off check.
As Bob Gardner explained, you can not afford a reduction in power during
your take-off roll by applying any amount of carb heat.
Happy Flying
Ron Clarkson
Keith Arnold
On Sun, 25 Jan 1998 16:07:15 -0800, Ron Clarkson
<Ron.Cl...@UAlberta.CA> wrote:
>Keith Arnold wrote:
>>
>> ======>
>> Absolutly right!!!!
>>
>> ô¿ô - Keith - 182L/STOL N3431R - Chino, California
>> N33° 58' 46" W117° 38' 41"
>
>Certainly Carb heat may not cause detonation!
>When your preparing for take off, and concerned about detonation OR the
>fact that there may be carb icing, lining up for take-off should be a
>decision that is best postponed.
>
>Knowing of course that Carb Ice can accumulate in conditions where you
>have above freezing temps. If you suspect carb icing, then you should
>ensure engine is warm, and any "suspected" carb ice has been ingested,
>during your run-up or pretake-off check.
>
>As Bob Gardner explained, you can not afford a reduction in power during
>your take-off roll by applying any amount of carb heat.
>
>Happy Flying
>Ron Clarkson
=========>
Don't you think we have to consider at what elevation we're at. The
guys that owned my 182 before me always used 75% power for take off.
that's setting the C/S prop for 2450 and 24" MP (why, I don't know).
Never hurt nothin'
When I'm at altitude strips (7000'+) the best MP may be 20" and, of
course, I lean also for -100 degrees. Carb heat has nothing to do with
that reduction in power.
All I originally said is using carb heat on take off with leaning as
necessary is not a problem. The PIC just needs to take the situation
into account. If the takeoff roll is going to put you past the abort
point *then* don't go.
karl gruber
Hi Bob,
I know I've seen an old airplane that required carb heat for takeoff.
But not for ice protection. It was to limit power. And, I think it was a
Luscombe.
If I ever get carb ice on the ground (can't remember the last time I
flew an A/C with a Carb!)I like to apply takeoff power with full carb
heat and then go to full cold just as the airplane starts to accelerate.
Seems logical to me that one good blast of heat can't hurt.
Karl
GRay
> ========>
> Is ping and detonation the same thing??
>
IF the description is the same as automotive,YES!
Geoff
--
To reply via E-mail,please remove the extra letter g from the address
line of my e-mail...
William W. Plummer
My recollection is that they are really quite different. One is caused by
the spark firing too soon before Top Dead Center (ping) and is equivalent to
too much spark advance. The other is caused by incandescent carbon deposits
causing detonation at the
wrong times, almost anytime in the cycle. Both are bad, however. --Bill
GRay wrote in message <6arcjn$b9j$4...@gte1.gte.net>...
Keith Arnold
On Fri, 30 Jan 1998 21:44:07 -0500, "William W. Plummer"
<wplu...@V-sign.com> wrote:
>My recollection is that they are really quite different. One is caused by
>the spark firing too soon before Top Dead Center (ping) and is equivalent to
>too much spark advance. The other is caused by incandescent carbon deposits
>causing detonation at the
>wrong times, almost anytime in the cycle. Both are bad, however. --Bill
>
>
>GRay wrote in message <6arcjn$b9j$4...@gte1.gte.net>...
>>> ========>
>>> Is ping and detonation the same thing??
>>>
>>> ô¿ô - Keith - 182L/STOL N3431R - Chino, California
>>
>>IF the description is the same as automotive,YES!
>>
>> Geoff
>>
=======>
William, my question was rhetorical. I know the difference but was just
trying to get Jerry to check it out. Thanks and IMO you are correct.
Eric Andersen
Have any of you thought about severe low temperatures that may require carb
heat to develop something close to full power? I'm talking about sub-zero
temps when the air is so dense you have to heat it to breathe?
Any of you ever seen a C-150 leave a contrail in the pattern?
Rod Farlee
"William W. Plummer" <wplu...@V-sign.com> writes:
>My recollection is that they are really quite different. One is caused
>by the spark firing too soon before Top Dead Center (ping) and is
>equivalent to too much spark advance. The other is caused by
>incandescent carbon deposits causing detonation at the wrong times,
>almost anytime in the cycle.Both are bad, however. --Bill
"There is a tremendous difference between detonation and preignition
in terms of what they are and what damage they do. ... Detonation is
caused by spontaneous combustion of fuel in the combustion chamber
instead of the desired even burning that normally occurs. Detonation
is the sharp 'ping' that your car engine makes but that, unfortunately,
you cannot hear in your aircraft engine. ... If the unburned charge
reaches a critical temperature, self-ignition and explosive detonation
take place. Extremely high temperature and pressure quickly cause
engine damage. ...
"Preignition (before the spark) is premature ignition of the mixture. ...
Preignition results in immediate full-scale increase in EGT. Tests at
Lycoming have revealed that it takes less than a minute for preignition
to burn a hole through a piston. ... Preignition can result from a hot spot
in the combustion chamber that ignites the fuel in advance of the spark."
- John Schwaner, Sky Ranch Engineering Manual, pp 159-166.