Need for Carb Heat?

GaryMac

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Joined
Sep 3, 2008
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814
Location
Colleyville, TX
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Building a Genesis G1sa
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Quick question.... I've seen lots of references to icing and carb heat, but never seem to see anything about installing and using carb heat on a gyro.

My plan is to use an HKS 700E, and you can buy a carb heat kit for it. Should I? Or is it really unnecessary?
 
I believe all carbed RAF's have carb heat. Mine does
Brad
 
The Subaru has an intake heater that takes heat from the coolant to insure that there will be no ice.
IMG_0893.JPG

This is on an injected engine.

I would have carb heat available for any carbureted engine. I would seriously consider intake heat for injected engines.

If there is a drop in pressure there will be a drop in temperature. Fuel vaporization further decreases this drop. According to the Aircraft Flying Handbook intake ice can be a factor when air temperatures are as high as 70F.

I have had carb ice on a 182 during the summer with the OAT showing greater than 70F.
 
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Thanks for the info.... I guess I'm not surprised that the RAFs and subaru powered ships have this..... I don't seem to hear the Rotax guys talk about having carb heat. Any of you rotax guys or HKS guys have this installed?
 
I have seen electric throat heaters for the Rotax 912. Our Rotax powered Outback 2000 airplane has carb heat.
 
HKS has a heat probe to prevent ice.

I took this from the FAQ on the HKS site.

The electric probe warms the carburetor body. It is generally used as a preventative. Unlike Carb Heat systems of conventional aircraft it is commonly left on continuously when operating in climate conditions where carb ice is possible. This does draw from the available electrical power. If running strobes, nav lights, transponder, com radio, etc. it may not be possible to maintain a positive charge rate. (17.5 amps at 12V) Because of the short intake track of the HKS, carb ice has not been as common as with a Continental, for instance. Remember, the cylinder head, to which the intake tube is bolted is running about 300 degrees F. Header wrap is sometimes used to insulate the intake runners effectively warming the carburetors. Alternate solution to deal with potential carb ice would be to pick up hot exhaust air and duct it to the carburetor Body. Conventional ducting through the intake is not a preferred method to deal with carb ice on the HKS
 
The HKS carb heat element will work on the Rotax 912. They both have the same type of carb. Another choice is to use liquid from the coolant. I think Leading Edge Air Foils sell such a heater the supplier is in England.
 
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need for carb heat

need for carb heat

on aircooled rotax I use the electric type, on water cooled I use the water to heat the carbs, without heat in cool wet conditions a single carb will ice in less than 10 min and a duel carb is only a little better. The one that rotax sells press on to the carb where the air filter fits and the filter fits on the heater , the only down side is it more weight on the rubber sockets,the heater adds a little and it puts the airfilter about one and half inch farther out but it works well.
 
Thanks, Michael. Looks like I should check into getting the carb heat option for the HKS, just to be safe.
 
I have seen one iced Rotax. The results were not good. Engine out caused damage to the aircraft and pilot. He subsequently refused to fly without intake heat.
 

Click the picture for more info on the HKS heat for bing carbs.
 
Turbocharging?

Turbocharging?

So if you had a turbocharger on a Rotax 912 would that increase the temperature of the intake air enough that you wouldn't need a carb heat system?
 
I believe that the turbo would provide more than sufficient heat to prevent ice. I have never seen a turbo system with additional heat. usually they do have an alternate air source in the event of filter blockage due to impact ice or contamination.
 
What is the susceptibility of the two stroke Rotax engines for carb icing?
 
I do not have data for specific engines.
 
What is the susceptibility of the two stroke Rotax engines for carb icing?

The 2-stroke Rotax engines can develop carb ice. I remember seeing a heater for Rotax engines just for that purpose.

I never had a problem with carb ice on any of my Rotax engines. One of the people in another flying club said he had engine roughness on his Rotax. When he landed he found frost in his carb inlet.
 
Engines which use carbs with sliders instead of butterflies for throttle are thought to be less susceptible to ice, but there are anecdotes of it happening on Bing carbs on the Rotax two-strokes.

Even the supposedly ice-proof POSA carbs are a subject of debate. Sonex says it's AeroCarb does not need carb heat; Ellison says its version does.
 
I iced one carb on my 912 uls that is on my Magni. Two other Magni flyers had shut down while flying high altitudes on their Missouri to Florida trip in their 912's. All these happened during the month of April. The 912 has manuel carb heat coming from a shroud around the muffler & has a carb heat gauge. It works well. Carb ice can catch you off guard the first time you experience it. I think all three of us will react quickly to the situation if it ever occurs again. Mine was running rough so I landed. The right carb was soaking wet. The other guys pulled the heat and restarted after a few seconds of thought.

Doug
 
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