Cook book recipe for a modern day V12 ! !

[Race5]

Re: Cook book recipe for a modern day V12 ! !

I think I would take a Merlin to an F1 supplier like Cosworth and tell them to duplicate it an modern materials, with optimized head designs etc. It would be more cost effective if they could sell them for use in stockers as well. I'm sure it could be done for enough$$$$. Someone just needs to step up and get it done.

[spacegrrrl]

Re: Cook book recipe for a modern day V12 ! !

Variants of auto engines can run at full power for extended periods. Nascar and some years of CART racing has proven that. Not to mention offshore racing. The issue has not been the engine, it has been the rest of the package needed to make it reliable. It takes a lot of effort to develop any engine conversion and to date there really hasn't been a reason to seriously pursue developing high output automotive conversions. To build an engine like a Merlin from scratch would be a HUGE undertaking. There are some great books about what was involved in developing the Merlin. (I have one of them, I'll try and find it later to get you the title).

I'd say leverage either offshore racing or Nascar. Offshore engines are making 1400HP for hours and constantly banging against the rev limiter when the boats come out of the water. There has to be way to put that in an airplane.

Michele

[John]

Re: Cook book recipe for a modern day V12 ! !

I think I would take a Merlin to an F1 supplier like Cosworth and tell them to duplicate it an modern materials, with optimized head designs etc. It would be more cost effective if they could sell them for use in stockers as well. I'm sure it could be done for enough$$$$. Someone just needs to step up and get it done.

Any way to set up new Merlin for higher revs? I think the maximum torque
efficiency occurs at about 5700 rpms for piston engines(if I remember right)
not that one needs more torque, but that the efficiency drops after that.
Also more revs gets you more HP.

[John]

Re: Cook book recipe for a modern day V12 ! !

...also, since we are throwing out ideas for a power plant, can we put our
brain power together and design a "new concept" Unlimited? (maybe on
another post that is)

"More power to ya" -as Mr. Darlin says on the Andy Griffith show.

[MRussell]

Re: Cook book recipe for a modern day V12 ! !

Variants of auto engines can run at full power for extended periods. Nascar and some years of CART racing has proven that.
Michele

Disagree.

[Wild Bill Kelso]

Re: Cook book recipe for a modern day V12 ! !

A little off topic but I want to build up a Lancair with a Subaru STI engine. It's 2.5 liters twin turbo that can produce 600+ hp without even going inside the engine. Opposed four, compact, light, and you can get a prop gearbox. And it will run all day long at max.

[Peashooter]

Re: Cook book recipe for a modern day V12 ! !

I think I would take a Merlin to an F1 supplier like Cosworth and tell them to duplicate it an modern materials, with optimized head designs etc. It would be more cost effective if they could sell them for use in stockers as well. I'm sure it could be done for enough$$$$. Someone just needs to step up and get it done.

That's what I'm talkin' about! (See my post above, complete with airframe concept.)

[Blue Foam]

Re: Cook book recipe for a modern day V12 ! !

Automotive engines can't work as aircraft engines, yet Nascar and offshore engines run all day at higher specific power than Mouse Merlins. Both statements are true...

and false.

To anyone who is interested in the theoretical side, simply pick up Taylor's books (Sloan Lab, MIT: pretty much Mecca for engine design) and go through the design process listed. What pops out is not that surprising, but it points out why no one has done it.

Building a small, high specific power engine is a simple equation:

1. Short stroke for low piston speed,
2. Small bore leads to detonation resistance and higher compression*boost,
3. Add up the number of cylinders for the required displacement,
4. Choose a configuration that is compact, yet has good primary and secondary balance and moment numbers.

Make this a large engine and we quickly run into a few problems:

1. The short stroke-small bore needed for high compression* boost means LOTS of cylinders and very inconvenient engine geometries.
2. Specific power (HP/lb) is inversely proportional to torque. So a light and powerful engine needs to be higher RPM, lower torque. This leads to the PSRU issue. Here, it is simply a matter of building it from EXISTING designs. Every helicopter ever made has high torque, low RPM gearboxes. Every turboprop. Most radials too! It is simply a matter of designing from the existing database and not trying to re-invent the wheel. However, aviation is not very good at this.
3. Manufacturing cost. Here the multi-billion dollar motorsports industry is our un-aviation-acknowledged savior. Milled blocks, heads, etc. can be had for far less than the current cost of a Mouse Merlin. It may not be cheep, but based on the dollars spent making so much metal this year in Merlins, it ain't THAT expensive.
4. The last kicker is HP/in2 of piston area. This is an odd and often overlooked factor that doomed many otherwise good engines including the RR Crecy, and probably would have doomed the Napier Nomad. More power means more heat, more heat per in2 means more cooling to a piston crown that has a laughable splash of crankcase oil occaisionally wafting in its direction. Welcome to melted pistons.

Solutions actually exist. Well balanced configurations such as the center output, V16 would fit nicely in the Merlin envelope at 1500 ci, with double the detonation resistance, lower piston speed, and far stouter cranks. There's already a gearbox on the Merlin, simply add modern gear tooth profiles, coatings, and lubricating architecture. Put dedicated oil spray bars in to cool the pistons and have teh drag block mill shops crank it all out.

The money, tech, and guts exists. So far, no one has done better than two out of three.

[MRussell]

Re: Cook book recipe for a modern day V12 ! !

Thanks for chiming in...
I've never heard of a center output V16... what is that?

[spacegrrrl]

Re: Cook book recipe for a modern day V12 ! !

So a pair of offshore large block turbocharged V8s per end with the power take-off in the middle of the engines and a PSRU that borrows heavily from helicopter gear boxes in a ground up racer designed to tip the scales just over the new "John Parker" weight limit. A small DO335 like racer with 2800HP per end should go pretty fast I would think....

Michele

[440_Magnum]

Re: Cook book recipe for a modern day V12 ! !

I think Spacegrrl has the right idea.

Automotive powerplants would work very well if they were designed corrrectly. The only advantage the aircraft V12s have over automotive powerplants is their large cubic inch size and the built in superchargers.
David

Sorry, but I disagree. The differences are much more fundamental. Things like PER CYLINDER displacement, peak RPM (low for aircraft engines), torque curve, physical packaging.... Pretty much everything.

Some of the most "airplane like" car engines are big-block v8s. They're even very comparable in displacement and power- a Cadillac 500 isn't that much different than an IO-540 in displacement or horsepower. But the IO-540 has 6 cylinders to the Cad's 8 smaller cylinders, weighs less, produces all its power at propeller-friendly RPM instead of 4000 RPM (and the Cad 500 is a SLOW winder for a car engine). And the IO-540 is rated to run at full power all the time- car engines loaf along at far less than 1/4 of their maximum power for 90% of their lives.

Any adaptation of a car engine to an airplane without Falconer-style total re-engineering of the whole structure is going to be a compromise at best. That's fine for experimental/sport plane apps, but its not likely to win races.

[440_Magnum]

Re: Cook book recipe for a modern day V12 ! !

Thanks for chiming in...
I've never heard of a center output V16... what is that?

Well, here's one from 60 years ago. Flew in two XP-47s after WWII:

http://www.aviation-history.com/garber/vg-bldg/chrysler_XIV_f.html

It had two separate crakshafts geared together at the center of the block. The output shaft ran from the center of the engine, through the crankcase above the the front crankshaft to the propeller gearbox.

[spacegrrrl]

Re: Cook book recipe for a modern day V12 ! !

Sorry, but I disagree. The differences are much more fundamental. Things like PER CYLINDER displacement, peak RPM (low for aircraft engines), torque curve, physical packaging.... Pretty much everything.

Some of the most "airplane like" car engines are big-block v8s. They're even very comparable in displacement and power- a Cadillac 500 isn't that much different than an IO-540 in displacement or horsepower. But the IO-540 has 6 cylinders to the Cad's 8 smaller cylinders, weighs less, produces all its power at propeller-friendly RPM instead of 4000 RPM (and the Cad 500 is a SLOW winder for a car engine). And the IO-540 is rated to run at full power all the time- car engines loaf along at far less than 1/4 of their maximum power for 90% of their lives.

Any adaptation of a car engine to an airplane without Falconer-style total re-engineering of the whole structure is going to be a compromise at best. That's fine for experimental/sport plane apps, but its not likely to win races.

You can't confuse the engine under the hood of granny caddy's with the built to race American V8. Other than some generally shared geometry they are totally different animals. Nascar runs flat out for hundreds of miles, Offshore racing boats run at full throttle for hours. You can build engines that are based on American V8s that last if you know what you are doing. As for the RPM that the peak output occurs at that is a non-issue since you would have to have a PSRU. If you think about the RPM that the turbine engine in a helicopter turns at you can see it could be done.

The biggest problem seems to be the "cross discipline" issue. For example, the original "Blind Man's Bluff" effort was largely the result of people with lots of knowledge of cars but none of racing airplanes. So they made mistakes like creating a fuel control that lost its mind and went full rich above 10,000 ft. This doomed the alcohol engines as all the oil was washed off of the cylinder walls. (Folks from the team gave a talk in Phoenix that I attended after the first Reno attempt where they explained all this, Skip was there as well, very neat talk! He said when they asked him is he'd fly it he took one look at how long the nose was and agreed immediately because he said he'd have so much time after he saw the nose hit the ground he was sure the cockpit would still be far enough off the ground for a safe parachute jump! He is a hoot!) The Pond Racer was what happened when you have the other side of the equation. They knew airplanes but not automotive race engines. Look at what happened when they tried to switch back and forth between gas and alcohol. No one on the team understood the fuel line material issues. Car folks would have.

My point (and it was a bit of a ramble) is that what you need is the right team of people that understand the airplane side, maybe even with direct experience building racing aircraft motors and the right team members that understand what works and what doesn't with race car motors. Finding the right combination of those two groups is the real challenge.

Michele

[speeddemon]

Re: Cook book recipe for a modern day V12 ! !

Offshore racing boats run at full throttle for hours.

Not to pick nits, but actually...no they don't. The throttleman is continuously jockying the throttles to keep the props from over-revving the engines when the boat pops out of the water, and to keep them from over-temping. They are on-off-on-off for the whole duration of the race.

[spacegrrrl]

Re: Cook book recipe for a modern day V12 ! !

Changes in power setting from full to off throttle are generally considered more stressful on the engine than running at a steady state. Also consider what the motor is going through, from fully loaded to running free and then abruptly placed back under full load. Way more hostile than an airplane application. About the only thing that is easy on an offshore race engine is that cooling isn't usually an issue.

Michele