EuroFlyer wrote:
Many Bonanza owners went through it. The real issue is the baffling of the engine
I am told that the easy way to avoid high CHT on the Bonanza is to remove the ‘eyebrows’ winterisation plate in front/top of the engine
Peter wrote:
Is this serious, or a joke?
No, that is the serious part. The joke is the mechanic suggesting not to fly when it’s hot.
GRIFF wrote:
I am told that the easy way to avoid high CHT on the Bonanza is to remove the ‘eyebrows’ winterisation plate in front/top of the engine
There is no such thing as an easy way to keep all the left hand cylinders cool. But I’ll have a look.
Arne wrote:
air-cooled engines have all but disappeared
Of my thirteen personal vehicles, six are liquid cooled. The main issue with most air-cooled engines for most applications is not high temperatures, but low temperatures. They are designed for use in stationary traffic, which leaves them running cool the rest of the time. They do however last a very long time given Nikasil lined aluminum bores, which allow tight running clearances regardless of low operating temperature. Along with electronic ignition, this is the thing that I think would make an air cooled aircraft engine better. The last thing I’d want to own is a liquid cooled aircraft engine, because they are a pain to maintain over long periods.
The main reason air-cooled engines have become less prevalent for e.g. motorcycles is the challenge of emissions controls when the engine is first started, and during the relatively long period over which it subsequently warms up given that it’s likely overcooled for the operation it is seeing. This results in a cold exhaust catalyst if the engine is so equipped, but doesn’t affect total daily emissions much unless all the use is short trips. The regulations are what they are, and as always they have negative effects (like less consumer choice in engines) as well as positive.
A secondary reason for liquid cooling is nothing to do with cooling itself – the mechanical noise of a liquid cooled engine is slightly less, generally not an issue for aircraft engines that have a large propeller making more noise than the engine.
Arne wrote:
So as long as radiator inlet temperature remains below boiling and the thermostat is working properly, a water-cooled engine doesn’t care much about outside temperature and self adjust to maintain very stable internal conditions.
Fair point, I did not think about the role of the thermostat; indeed as long as the engine does not need the full capacity of the radiator the change in OAT makes no difference. It only becomes a problem when it the thermostat needs to be fully open to remove the heat.
My point was slightly different – when the water cooling system is at the limit of its capacity (for a given air flow and OAT), then a change OAT has more of an effect than for an air cooled engine, I think.
On the other hand, the consequences will be coolant boiling off with the engine still around coolant temperature, which causes less damage than cylinders approaching their melting point… it looks more spectacular, though!
One of the reasons that Robin aircraft can outperform their American rivals is the attention paid to cooling drag, if you look at a Robin from the front you will see that the engine cooling inlets are considerably smaller than an American aircraft of the same HP.
The advantages are less drag and in the case of the O-235 not being overcooled ( as in the C152 ).
The down side is when operating in a very hot climate the oil temperature is normally the limiting factor in the climb and CHT is also an issue.
So I can see how an inexperienced pilot who is practicing forced landings and climbing after the practice repeatedly could do considerable damage to the engine.
Don’t they have a CHT gauge?
I am not sure of this is generally true but a CHT gauge is a certification requirement. It may have been an FAA one however.
CHT & EGT are not standard fit on most Of the smaller Robin Aircraft but are available as options.
Robins are being used as towing planes for gliders, constantly climbing, with full power, then descending and immediately picking up the next guy. In all temperatures.
They wouldn’t have gotten a certification if they had a problem.
I think this is utter nonsense. There must be something wrong with the engine cooling, or the engine has been operated in the wrong way, i.e. too lean.
