carb icing

[paramotormac]

has anyone got any advice on how to get round carb icing

[morgy]

dont fly in the cold

sorry

[helimed01]

has anyone got any advice on how to get round carb icing

Dan the camara man had trouble with carb icing using a Bing carb. Although he didn't cure this he improved things by making a pipe that supplied the intake with air from close to the cylinder head - warmer air.

He now uses a Walbro carb but doesn't get as good economy on the Walbro, from approx 4 ltrs an hour to 5.

Fly with a Bing in the summer and Walbro in winter????

Might help things.

Whitters.

[garyfreefly]

I was told when learning to fly microlights keep it reving while you decend.......(not all the time) just keep blip-ing it.....when you fly through mist /fog you are at the most risk so try not to.....I did all this and still had to do a forced landing on a beach.......you could actually see the ice in the carb (and it was fitted with a heated inlet manifold )10 mins later the engine heat had melted off the ice so we took off again and it never did it again ....still dont know how we could have done anything different to stop it happening.....I still rev when decending to this day even with the paramotor.......and have never had the same problem

[pete_b]

I was told when learning to fly microlights keep it reving while you decend.......(not all the time) just keep blip-ing it.....when you fly through mist /fog you are at the most risk so try not to.....I did all this and still had to do a forced landing on a beach.......you could actually see the ice in the carb (and it was fitted with a heated inlet manifold )10 mins later the engine heat had melted off the ice so we took off again and it never did it again ....still dont know how we could have done anything different to stop it happening.....I still rev when decending to this day even with the paramotor.......and have never had the same problem

Dont keep a constant RPM increase and decrease as you fly

[bendmeroundthehedge]

The motorcycle fraternity (the non-fuel injected ones) are using Silkolene Pro FST.

http://www.silkoleneoil.com/techtip7.htm

Kev

[Phil_P]

Well the first thing to do is get over the misconception that carb icing is significantly more likely to happen in the winter. I think that you will find that this is not the case.

Carb icing is NOT particularly temperature sensitive insofar as it happens at temperatures significantly above freezing, as it is the action of the fuel atomising that causes the temperature drop. What you need to be aware of is the relative humidity and dew points. Have a look at this chart to get an idea of the danger zones.

http://ibis.experimentals.de/images/carbicingfromcaassl14.gif

It is more likely to occur at lower throttle openings, and therefore is a significant risk during the descent phase of flight. If you find your engine to be particularly susceptible, then making your landings 'dead stick' may be of value.

The ideal solution for carb engines is to duct warm air into the carb inlet, this will reduce humidity and increase temperatures so reducing the likelihood of icing. However, it is preferable to be able to switch off this warm air, so that your engine can make full power during critical phases of flight, specifically take off, when the chance of icing is slim. In GA, it is usual to apply carb heat at intervals during flight, and also on the downwind leg of an approach pattern.

It must be remembered that if a switchable carb heat system is employed, then it must be used for a long enough period to be effective. In the presence of ice, initially selecting carb heat will result in a rougher running engine as the ice melts and is ingested into the engine. Revs will then be restored to pre ice levels.

A simple flap valve in an intake pipe could be made to work well, with a very simple push pull control.

Phil