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ptag.dev(at)tiscali.co.uk Guest
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Posted: Wed Feb 11, 2009 12:19 pm Post subject: Carb ice on a 912 |
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Hi! Gilles
I can vouch for my ex-jabiru 3300 getting ice three or four times once
in the UK on very hot and humid flight in the midlands, second time
departing from Southend direct to Denmark about 20 miles out about 2,000
ft level, third time crossing Sweden same height (with nothing but rocks
lakes and damn trees as far as one could see!) all in June. Fourth time
going straight out five miles from LeTouque at about 1000ft probably in
August. ALL VIVIDLY MARKED ON MY BRAIN! In all cases engaging carb heat
caused a further little engine cough with no further problem. The carb
heat was a simple flap valve enabling warm air from round the muffler to
be fed to the air box.
I'm convinced that the engine knows when you are in the most critical
part of your journey to give a cough !
Regards
Bob Harrison G-PTAG(now with 914 and Bell Intercooler and no carb heat
YET!)
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rampil
Joined: 04 May 2007 Posts: 870
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Posted: Wed Feb 11, 2009 1:37 pm Post subject: Re: Carb ice on a 912 |
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Drawing air from the engine compartment may prevent many cases of
carb ice but at a tremendous performance hit of using only heated air,
and with no ram pressure effect. No one flys a cessna with carb heat on,
full time, and carb heating has been cited by the NTSB as responsible for
crashes in attempted go-arounds.
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_________________ Ira N224XS |
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occom
Joined: 26 Aug 2006 Posts: 404
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Posted: Wed Feb 11, 2009 2:12 pm Post subject: Carb ice on a 912 |
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I don't know how this carb was iced, but it claims this is an example of
carb icing. It's from an ad for carb body heater. Thery fact that they had a
camera and an icy carb together at the same place makes me think it was
staged, but still; here is an icy Bing
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ptag.dev(at)tiscali.co.uk Guest
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Posted: Wed Feb 11, 2009 5:41 pm Post subject: Carb ice on a 912 |
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Hi! Noel
I had an early Austin A 40 my first car it was fitted with a zenith down
draught carb gave me lots of problems and many journeys had to be run at
very low RPM until I got pissed off with it pressed it hard for a few
miles stopped and jumped out to look under the bonnet to find enough ice
to operate a bloody oxygen plant ! Can't remember what I did to it other
than sell it !(happy days)
Regards
Bob Harrison
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Roger Lee
Joined: 10 Jan 2006 Posts: 1464 Location: Tucson, Az.
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Posted: Wed Feb 11, 2009 6:40 pm Post subject: Re: Carb ice on a 912 |
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Ok here is a more official word even if I have to eat my own. I will always seek out a good answer and I admit I need to adjust my thinking some. Here is an answer from Eric Tucker from Rotax. I sent the picture to Eric and ask his opinion.
Hello Roger
Do I believe it, yes...in England they have high humidity and the temperatures that make any engine with a carburetor prone to icing. (Due point and temperature match) Any venturi that moves air will experience a temperature drop, if that drop occurs and brings saturated air into the engine venture at the freezing point of moisture, bingo carb ice. While it may be unlikely that a Rotax will ice, it can and has happened in my experience. In most cases the engine bay is so hot, due to the fact that most installations do not have baffles and very few OEM do any airflow testing, the engines are sucking hot air from inside the cowlings. Hot air robs a bit of power, but protects against ice. In the case of exposed engines, as in most UL applications, the operations are normally not in these conditions, it’s just too cold to fly in saturated air even at mild temperatures up to 70 degrees.
I personally like the hot water systems that they have developed, they do not cause a loss of power because they do not heat the air, they heat the carb body were the ice forms. In addition it should be noted that the guys in the UK who developed this are long time aircraft supply people and both of the principals happen to be engineers. They also developed the “soft start” module for the ignition. Rotax liked the idea so much that it will be built into the ignitions starting mid 2009.
Regards,
Eric
P.S.
I hope this helps all of us.
Roger Lee
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_________________ Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
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Float Flyr

Joined: 19 Jul 2006 Posts: 2704 Location: Campbellton, Newfoundland
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Posted: Wed Feb 11, 2009 7:31 pm Post subject: Carb ice on a 912 |
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When I was a little kid my father had an A-40 in Glasgow. His friends used
to joke it was the only "loy" car in the UK. Loy is what they called body
filler. It never ran when it was needed and there was only one window
crank. When he bought it the left indicator was shot. He had that car for
the full four years we lived in Scotland. I never asked what happened to
that car when he finally left Scotland. I expect it may be an anchor at the
bottom of Loc Dhoon.
I remember visiting one of his friends once and going for a drive in his
Rolls Royce. Want to talk about culture shock! Go from the remains of a
well abused A40 hanging on by a roll of cotton thread and a wad of chewing
gum to a brand new Rolls Royce! Being a kid I liked the tables in the back
seat.
Noel
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_________________ Noel Loveys
Kitfox III-A
Aerocet 1100 Floats |
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grahamsingleton(at)btinte Guest
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Posted: Thu Feb 12, 2009 1:26 am Post subject: Carb ice on a 912 |
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Dave G wrote:
Quote: | I don't know how this carb was iced, but it claims this is an example
of carb icing. It's from an ad for carb body heater. Thery fact that
they had a camera and an icy carb together at the same place makes me
think it was staged, but still; here is an icy Bing
Dave
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that's the photo Nigel Beale took and yes it was done on the ground
after an in flight occurrence. This was the trigger to develop the carb
heater.
Graham
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Gilles.Thesee(at)ac-greno Guest
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Posted: Thu Feb 12, 2009 3:23 am Post subject: Carb ice on a 912 |
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Robert C Harrison a crit :
Quote: | I can vouch for my ex-jabiru 3300 getting ice three or four times
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Hi Bob,
This was only a tongue-in-cheek remark about some Jabiru woes...
Best regards,
--
Gilles
http://contrails.free.fr
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