Carby Heat

[Geoff_H]

Has anyone experienced carburetor icing in a small aircraft engine. I am designing a small Cri Cri look alike and am considering putting cab heat to both engines. At present my thought are for wrapping carbs in insulated heating wire (final design very much unknown). But is this necessary, does anyone have carb heat on their small engine, very small aircraft?

 

 

[SSCBD]

Yes on a two stroke with an engine shut down.

 

 

[Old Koreelah]

Geoff this forum has had several threads devoted to carby icing and the consensus seems to be that electric heating wouldn't do the trick. If you get icing, you'll need a very rapid increase in intake air temp. Design rules call for around about 50C increase in a few seconds.

 

 

[Geoff_H]

The engines I am using are very small. My calves show that to vaporize the fuel requires 400watts, and by fitting a thermocouple to the carby the heat would come on when the temperature approached freezing and warn the pilot to icing as well as turn on the heat. 25 amps at 12 volts is not easy but maybe possible, hearing that someone has had icing on a two stroke makes me want icing of some sort, maybe engine or exhaust heat, but both seem heavy....room for thought. Anybody done it on a smash engine?

 

 

[flying dog]

Small engine, SMALL HOLE FOR THE AIR, thus: quicker blocking if ice happens.

 

Also, the greater the ice(water)/fuel mixture will be. that means the noise will stop quickly too!

 

Good luck.

 

 

[KRviator]

Yes, in a 582-powered Drifter during a low-power descent that caused an engine failure and landing in a paddock. When I went back to look at the charts, I couldn't have been any more in the middle of the "Severe Icing - Any Power" regime, but until then had been told "It's a two-stroke, it can't ice"....yeeeaahhhh, right...

 

 

[facthunter]

The longer the distance to the port, the more likelihood of icing. If your engine is a single and piston ported there is a fair amount of hot gas stuff going in and out of the port and helps if the carb is behind the cylinder as well, and close. Might be worth while to measure the temps at the carb(s) to see the extent of the problem. A carb temp gauge would be useful on a lot of installations. Nev

 

 

[Geoff_H]

I think that a carby temperature gauge should be a highly considered item if you do not have effective carby heat for any aircraft. I calculated that my little 15HP engines need 400Watts of heat to counteract the evapourisation cooling of fuel at full fuel flow. I am trying to work out a way of getting that much heat into the carby throat. Any ideas anyone? But on the changes to the fan cooling I would do a weight and balance check after modifications to see that the CofG has not moved significantly. A movement rearwards will reduce aircraft stability, albeit I would expect only slightly, but its an easier ground check than an in air check.

 

 

[facthunter]

I've flown a plane that had electric heat to a Bing CV carb. I used it all the time but how would you really know if it was effective? OK no icing, but without a temp gauge no confirmation. IF you mount a carb direct to the cylinder of an MZ etc you will get a fair bit of heat transferred from the engine directly through the carb body. This would probably be adequate if direct contact with an"O" ring to seal is the way of mounting it. A small bleed pipe off the exhaust would be enough otherwise. This was enough on early Douglas motorcycles that were otherwise prone to icing. They also made an aero version OHV 750cc.. Nev