Pizza oven CHT temps

[flightlogic]

I do like some adventure in my daily activities. It is days like those shown below that cross my threshold.
I did run like heck after getting out though.....

[AJ85WA]

I think what you did was a great choice,guys please take some time to learn about your engine and the "actual" limits. Here is a snippet copied from Mike Bush regarding CHT

" I do not like to see CHT above about 400?F, which is the temperature at which the aluminum alloy from which your cylinder head is made loses one-half its tensile strength. (The strength decreases rapidly as the temperature rises above 400?F.) For legacy aircraft, I recommend a maximum target CHT of about 380?F just to provide a little extra cushion, and consider any CHT above 400?F to be grounds for "doing something right now" to get it down"

Safe flying guys

AJ

[db1yg]

Hey Nick,

Better to verify that it was simply sitting with no airflow across the cylinders too long on the ground than to take off and find it was something else!!!!

Looks like two people "cut and paste" from Mike's articles!

Holy Cr##----is that the remains of a Piper---and what happened??

See ya at the "office"!

Cheers,

db

[LettersFromFlyoverCountry]

I hope people aren't criticizing you for exercising caution.

I like to think that I'd have done the same thing.

Everyone has the standard by which a plane has to prove it's ready to fly. This one violated yours and you acted according to your standards.

I salute you.

[RV10inOz]

And pointing into wind may not be the best for airflow!

Yes that is counter intuitive.

But until you have tufted your engine, including piano wire hanging tufts and put a video camera in there you will never know.

I can't speak for the entire GA fleet, but tests done by a famous FAA DER and certification company found that sitting into wind actually gave no airflow and tail into wind created airflow. Yep…..that is not a misprint.

DanH is the resident airflow tester, I wonder if he has done these tests.

Tail draggers not such a good idea as the prop makes some interesting forces at that angle.

[flightlogic]

To be sure.... I see no criticism here in the thread at all... as the OP.
Some was tongue in cheek... but the main point of posting was to generate dialog, and observations. They often surprise.
Tail into the wind... worth looking into and not what one would think.
At any rate, I personally thank all those who reply... as always, I find the site a
thought provoking forum for all RV topics wide and near.

[David-aviator]

Mike Bush writes good stuff, most of it I believe comes from personal experience. If one does as he does an engine will run over 4000 hours as he has done. I've heard him speak a couple times at OSH, he's good at what he does.

But that being said, his business is restricted to certified aircraft where the envelope is much tighter and the outcome more predictable. He offers advice but in practice he works only on certified airplanes, which is good for saving money in that world and here with experimentals. Nothing bad about that. But from a practical point of view and factoring in experience, I still would have taken off like I said. That's life in the real world from my perspective which may or may not be worth anything.

I've read, not from Mike Bush but another mechanic, never take off with oil temp below 170 - for long engine life.

HA-HA! I'd have long engine life all right. I'd seldom fly. Most days this winter I feel good to get it up to 170 inflight.

It would be nice if this world were perfect, but it isn't.

[Weasel]

Why is all of a sudden 400 deg F some line in the sand (that one person has drawn) that is the determining point of a go or no go cooling limit for everyone?

I understand that at ~400 deg F the alloy of aluminum that these heads are made of is roughly one half the strength that it is at room temperature......so?

Lycoming and Continental both know that and have researched it a lot more than Mike Bush. They set the limits where they did because even it the metel gets softer, it still is strong enough to hold together.

Now don't get the idea that I am saying its ok to fly with CHT at 500 deg F all day. I am not!

If my CHT ran at 500 deg F in cruise or even close to that I would be trying to change something.

ECI says 435 deg F is ok all day long and the cyl's will easy go to TBO at that temperature. I asked personalty at OSH.

Before you start lobbing tomatoes at me my CHT's all run below 400 in cruise on the -10. There are a lot of planes that I fly that don't have CHT gauges. Some of them have baffling set ups that look terrible yet the owners and mechanics insist they are ok. Have had no problems on these.

Hope I didnt start a war

[DanH]

Gents, this is not about a particular CHT value being acceptable or unacceptable.

It's a about a pilot spotting an abnormal value while on the roll, "abnormal" merely being not what he usually sees.

Last summer I went for a hop with a visitor. Right at rotation he suddenly relaxed back pressure and chopped the throttle. As we rolled out and turned off the runway, I asked "What's up?". He responded that the stick didn't feel right. It took him about 3 seconds to determine that the elevator trim was not in its usual position.

Yes, he could have continued the takeoff, if he was sure it was the trim setting. He wasn't sure, and didn't waffle, as a 100% sure outcome option (abort) was available. I'd fly with him again.

[DanH]

Originally Posted by RV10inOz

[b]I can't speak for the entire GA fleet, but tests done by a famous FAA DER and certification company found that sitting into wind actually gave no airflow and tail into wind created airflow. Yep?..that is not a misprint.

But without hard data it is an anecdote.