It typically takes higher manifold pressures along with the hot induction air to do that. I wouldn't take off with carb heat on. On downwind, leaning to get smoother operation with carb heat, should be no problem. Better than loading up the induction manifolding with puddling fuel that causes hesitation or failure in an overshoot. We had a Citabria that would do that.Two basic things happen. Density altitude goes up that the engine sees which causes the engine to go rich. Potential detonation can happen if you try and lean to regain some lost power. Summer time the engine might see 150 deg air where as cold winter might be less than regular summer.
That’s a darn good question. The engine in question is a modified Gipsy Major and as designed they have carb heat linked to throttle which only comes on at or near idle power. Weird, I know, but it works. What may be even weirder is that it takes heat not from the exhaust but by drawing air in from alongside the crank case, which in practice has shown for nearly a century now to be sufficient.How many rpm does it drop?
My Auster had that same throttle-linked carb heat, and I had carb ice once or twice. Maybe that old cowling was leaking a bit. The heat is taken from the side away from the cooling air inlet, and it should be plenty warm in there with minimal airflow.That’s a darn good question. The engine in question is a modified Gipsy Major and as designed they have carb heat linked to throttle which only comes on at or near idle power. Weird, I know, but it works. What may be even weirder is that it takes heat not from the exhaust but by drawing air in from alongside the crank case, which in practice has shown for nearly a century now to be sufficient.
So my basic plan is to have it draw warm air from beside the case all the time. Others have done this and it’s worked out fine, I’m just curious if there’s approximate guidance on how much power I’m leaving on the table. At the density altitudes I’ll see it doesn’t really matter much anyways.
Mods done to the engine prevent the stock system from being installed, the biggest being that in switching the whole engine from inverted to upright it needed a change from the stock downdraft to a different updraft carb. The stock valve/hot intake/flame arrestor assembly no longer fits and OTOH may be an integral casting with the stock carb body anyways. Perhaps something can be fabricobbled to function the same but I’d just as soon get it flying this summer and make that next winter’s problem. This project has gone on long enough and really needs to fly before the unintentional tontine of partners is down to a single owner... and it’s close.If it works, why do you want to change it?
In a Lycoming, maybe. Water can exist in liquid form down to -20°C and causes airframe icing. Carb ice is one of those things you have to to watch for all the time, and when checking the METAR before you fly, look at the temperature and dewpoint to see how likely it will be for your flight. This is something not taught nearly often enough or aggressively enough in flight schools, and the appalling accident rate due to carb icing proves it.I understand when it goes below -5°C icing is pretty much not possible anymore, for the lack of moisture in the air.... - still I WOULD keep the needle out of the yellow....
[In reality - I would try to avoid to have to fly in sub-zero! Keep it tropical!!]
...are you referring to the "collective up" if the carb-heat-assist linkage-friction is too tight?You may be making Robinsons work, but for the uninitiated, having the auto carb heat linkage that will crash your chopper if you test it at idle is always the kind of fix you avoid.
I’ll have to seek him out, thanks.If you have access to the Moth club magazines there were a series of tech pieces about 2001/20002 about converting to selectable carb heat on upright Gipsy 2 due to less effective deice on the upright engine. I think Mike Souch of Aero Antiques in the UK had a lot of involvement in this and in some conversions of GM to upright so maybe contact him through the DH 60 Facebook group, he is a good guy.