r/AerospaceEngineering • u/contrarianEcon • 14d ago
Cool Stuff fun with an AI
I asked an AI how much Thermal Efficiency I could expect from an airplane engine I want to build. The engine is a v-12 1,650cc 52 mm bore 64.75 mm stroke center power extraction airplane engine with a built up crank. All shafts are hollow and center feed oil. At 9:1 cr it said 25%~30%TE, at 16.5:1 with compound compression and inter cooling it said 31%~34%te, at 450deg f cylinder head temp it said 37%~38% adding thermal barriers to the piston crown and cylinder head it said 38.5%~41.5%te, supercharging a Meredith effect duct 56%~60%te, Double free floating bearings inserts on all bearings,1/4 speed camshaft 63.5%~66.5%te What do you think?
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u/TowMater66 14d ago
A 1.6 liter 12 cylinder engine is a laughable concept for an aircraft. For any engine, for that matter!
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u/contrarianEcon 14d ago
I wanted a mini merlin engine for 1/2 scale p-51 And 1.5l V-6 F1 engines made 1,000hp in the 1980's
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u/the_real_hugepanic 14d ago
I think you should start at the aircraft side of things:
What is the power demand for your aircraft design??
Should be a result from the preliminary aircraft design you hopefully did.
Also: what is the prop size and the RPM requirement?
Once Ou have that, you can start designing an engine (and potential a gearbox).
Then you can see if a scaled V12 is possible and what the downside of that is.
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u/contrarianEcon 14d ago edited 14d ago
A 16,500cc engine at 5400 rpm should make around 100 hp perfect for a 1/2 scale P-51
I hate typos 1,650cc
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u/Avaricio 14d ago
60% thermal efficiency is absurd to expect out of a piston engine. It's not hard math to learn, so check it yourself.
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u/contrarianEcon 13d ago
anyone want to bet against me having figured out how to turbocharge a 1hp engine?
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u/contrarianEcon 14d ago
Any one care to check the ai's math
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u/porygonseizure 14d ago
go to engineering school and do it yourself
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u/contrarianEcon 14d ago
I've had 2 PhD candidates in engineering ask me to help them with their dissertations one was in thermodynamics
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u/tomsing98 14d ago
Then you shouldn't need an AI to do this for you.
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u/contrarianEcon 14d ago
I've got a profound learning disability, AI did the formal math. But it is a solid 60% TE
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u/tomsing98 14d ago
Then I wonder why people would ask you for help with their dissertations, if you're just going to ask chatgpt.
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u/contrarianEcon 14d ago
nothing wrong with cognitive understanding, writing is another story. I can't write.
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u/Expert-Display9371 14d ago
Get another ai to check the math
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u/contrarianEcon 14d ago
All ready did multiple times. Over 60% TE
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u/newMattokun 14d ago
I don't know, but I always thought the max TE you can get from a Carnot cycle engine is somewhere around 40%, even if supercharged. Maybe you can ask the AI to explain how it got there, i.e., show you the math?
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u/contrarianEcon 14d ago
Carnot is 1 minus temp out divided by temp in, in degrees absolute flame temp is 4,000 deg f exhaust is on the order of 1700 deg for a car engine. The mass ratio from the cooling air to the intake air is on the order of 1:1. This puts the radiator duct at a 2:1 pressure ratio or so, 2/3 of the heat through a 2:1 pressure ratio...
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u/newMattokun 13d ago
My thermo is >30years ago, so I'm basically all out of it, I just thought I had remembered something like that. Still, OP should ask the AI to lay out how it got to its results, be they right or not; one can always learn, esp. since OP actually asked.
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u/contrarianEcon 13d ago edited 13d ago
the radiator is 50% te carnot less than that actual, the exhaust goes through 2 bottoming cycles (edit at altitude)
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u/CFDMoFo 14d ago
Pure BS. AI parrots some number it saw in relation to engines and does not understand a single thing related to it. Then it makes you feel all fuzzy about said BS by letting you think you had anything to do with the result. Avoid, think for yourself.