Aircraft that operate at sea level.

As you have no experience as a pilot, you’d not be aware that it’s possible to be operating at sea level so far as the engine is concerned, even though it’s higher than sea level. Indeed, it’s possible to be operating below sea level so far as an engine is concerned, and that’s where it’s particularly important to keep within the parameters in the engine limitations section of the flight manual/POH.

Finally you and I can agree on something!:ok:

So what! I can start a thread on 'that year" and it will still have the same stuff in it.

Yep, unless you want to post your CV. From what I can tell you were a lawyer from CASA If you have any engineering qualifications then I will defer to your experience. If you don't then the "probably" becomes a "definitely".

So where the manufacturer states, 50 deg C, 100 deg C, and 125 deg C rich, the CHT is not at peak, and longevity does not suffer, however fuel consumption does?

Quite possibly because they are going through the courts in the USA at the moment. Internal issues it seems.

Engineering I do well. Law is a retirement hobby and I’m getting OK at it. However, there are other things I’m really good at that you’ll see when we meet. :ok:

Errrm, at post #150 you said “On the attached chart, the CHT does not peak at 25 degrees C ROP.”

We’re still waiting for the chart that you posted to be released by the PPRuNe gods.

I agree that CHT does not peak at 50C or 100 or 125 C rich of peak. I said CHT peaks around 25C rich of peak EGT. Are you :confused:

We ought to be grateful that yr_right/connedrod is the voice for the perpetuation of the old wives tales. There is a much greater number of people who solely read these forums rather than post, many of which are newcomers to the industry. Hopefully the coherent, well structured posts containing DATA from the sled and balloon might might motivate those readers to be curious, ask questions, read some pelican perch(as a start) and then draw their own conclusions. Team OWT is doing itself a disservice with its verbal diarrhoea.

Where's Jabawocky these days? Chocky frogs need dishing out!

You make the most important point: Find the data and rely on the data.

Don’t rely on what APS or anyone else says, except to the extent that their assertions are supported by data.

Jabba’s busy doing some good work that will result in a revision of the AWB.

Good news, tio540, your images have been released by the PPRuNe gods.

I’m pleased to say that my guess was correct. The images are of the EGT/CHT plots in many EDM manuals.

To the extent that those plots show that EGT and CHT ‘track’ each other always, they are bull****.

CHT ‘tracks’ EGT while mixture is being leaned from rich of peak towards peak. Then something interesting and counter-intuitive happens, approaching and passing peak EGT. From around 25C rich of peak, CHT peaks then starts to decrease as mixture is leaned further. As a consequence, the CHT at peak EGT is lower than CHT is around 25C rich of peak.

As I noted in earlier posts, this outcome is, despite the plots in EDM’s manuals and ironically, observed on every EDM (and other engine monitor) that takes measurements on real engines in the real world.

Okay, with my limited experience, I only recall one POH specifiying 25 degrees C ROP, all the rest varied between 50 deg C to 125 deg C ROP. So you disagree with EDM, and many manufacturers avoid the 25 deg C ROP. Then you agree with the manufacturers, mostly anyway.

I “agree” that the worst place to run your engine is at an EGT of around 25C rich of peak. That’s because it’s the mixture around which your CHT will be maximum and you’ll be giving your engine the hardest (and unnecessarily hardest) beating that you can give it.

I don’t “agree” or “disagree” with EDM, other than to say that their EGT/CHT charts are crap to the extent that they falsely represent CHT and EGT as ‘tracking’ each other always. There’s some other folklore in the EDM manual but I ignore it.

I don’t “agree” or “disagree” with engine manufacturers, except to the extent that some of their publications contain crap.

But whatever the facts and the bull****, doing piston engine management properly depends on you having an all cylinder engine monitor and you knowing what it’s telling you and why, and what if anything can and should be done about it.

As it turns out, I flew the DC-6 for 8 years. All 3 seats.


It is bollocks. Oil systems are vented, Oil tanks are vented. They have to be, a sealed system would rupture due to expansion of the oil as it heated or from crank case blowby.

No doubt. it's a persistent myth. THere's also a fair number who believe in the downwind turn. Nonetheless it's a myth there's no technical basis for it, nor has it ever been verifiably demonstrated under repeatable conditions.

Sorry, I thought that was more of a rhetorical question.

[QUOTE=lo_lyf;10111148]We ought to be grateful that yr_right/connedrod is the voice for the perpetuation of the old wives tales. There is a much greater number of people who solely read these forums rather than post, many of which are newcomers to the industry. Hopefully the coherent, well structured posts containing DATA from the sled and balloon might might motivate those readers to be curious, ask questions, read some pelican perch(as a start) and then draw their own conclusions. Team OWT is doing itself a disservice with its verbal diarrhoea.


Its one thing to run with theory but real world engineering dose not run on theory but with what is acutely and accurately occurred and shown.
What you and others do not understand and cannt be told or shown is what the exhaust gas is doing. The energy of the gas has not all been exhausted in the chamber and as it exiting past the valve it is still burning and as such damages the valve. This is not theory but fact. You can run all the dnyo runs you can wish for but the prove is the exhaust valve.
I dont no anyone or operator that run 25 deg rop. Normal is 75
Rop.
I will say it again. They stated that as you lean the mixture the burns faster than a rich mixture. Tbis is incorrect statement in fact it is reverse. If they get this basic rule wrong what else have they got wrong as it seams pently as i have shown.
Because i and others dont agree with the statements made at an UNAPPROVED course dose not mean we are wrong and dont have the right to have an opinion.

Where dose it say on any manual that you can spilt the magneto timing. Btw this isnt something that aps has found its been known well before they ever thought of it. So why is this happening why dose it work i guess leadie you wont answers this question as you havent answered any others i guess because you cant.

We all know too much heat is detrimental to the engine. However, we are talking about a heat engine here so the thermodynamic efficiency increases with temperature. If the materials could take it we would run them hotter. It is always a compromise. It is too simplistic to say that colder is better. You could run at rich best power and get the same CHT as if leaned to BSFC but more power and a cooler exhaust valve. There are no free lunches.

Really hard to read your fragmented gibberish, so not 100 percent sure I follow what you're asking but just as a single example the magneto timing for a Continental o-300 is 26 degrees BTDC for the right magneto and 28 Degrees BTDC for the left magneto. That is from the Type Certificate Data Sheet.

Yes that is one engine. Were dose it say it for example a io520 ?
Gibberish or dont you understand whats happening with the engine chamber ?
Btw the engine manufacture holds the type cert for the engine however the airframe manufacture takes control of the engine when fitted into their airframe and as such their data for the engine takes precedence over the engine manufacture.

And yet, you're holding up Ernest Gann as a technical expert merely because he wrote some popular books.

Detecting irony is not your strong suite, is it?

There is this thing they call it cowl flaps i do believe not fitted to all aircraft though. Most problems with cylinder cracking is due to the use of older cylinders being reused after an o/h. Thus said they are far more susceptible to cracking due to the Parthenon known as fatigue. To be honest i cant remember the last time i had to change one on a 1st life for cracking. But more than i can count on plastic aircraft with burnt valves useing lean assist.

Yeah, it was those rare float equipped metroliners. :E

If that's a serious question, there is a myth that you can get an airplane in flight "On the step" in a similar way that a boat or floatplane will get "on the step" and that once "on the step" the airplane will cruise at a higher airspeed with the same power. Yeah, it is complete nonsense. In order to do that, there necessarily must be a reversal in the drag vs. airspeed curve. Yet in 70 something years of pretty extensive empirical testing in wind tunnels and such, nobody has ever observed this reversal of the drag curve. So, the question is how is it that this "step" can be reliably detected by the hundred dollar hamburger crew with the low resolution analog airspeed indicators in the panel of their bugsmasher, but all the aerodynamics and all the aeronautical engineers in all the research institutions and air-frame manufacturers around the world have not been able to detect this "step"? It just seems unlikely, doesn't it?

Yes, a boat or a floatplane will "get on the step" and once on the step it is in fact possible to cruise at a higher speed with less power than at a speed below "the step". The reason for this is that the boat is operating within two fluid mediums, sir and water, one of whcih (water) has far greater drag. when a boat is traveling slowly, it is in displacement mode, that is to move ahead, it must move all the water displaced by the hull aside or beneath the hull. That takes power, because compared to air, water is dense and viscous and hard to move. As a boat hull reaches a certain speed the boat begins "planing" where hydrodynamic forces will lift the hull out of the water, so that the boat is being supported primarily by the hydrodynamic forces rather than the buoyancy of the hull. With a float-plane, obviously, some of the weight is being supported by lift on the wings. This is easy to observe in a hydroplane; virtually none of the hull is in the water, it's skimming across the surface. This reduces drag in two ways: first, the hull is no longer displacing much water as it moves, and second because less of the hull is in the water, there is less skin friction from the water. The portion of the hull that has been lifted out of the water is now moving through air, whcih creates far less form drag and skin friction.

In short, a boat gets "on the step" because in planing mode, most of it is lifted out of the water which is creating the vast majority of the total drag.

There is no equivalent effect with an airplane in flight. The airplane is moving through a single fluid medium, air. It is not lifted out of anything as a boat is when planing, the entire aircraft remains submerged completely in that single medium.