Exhaust Flow and Aero

[interested bystander]

Great brain - tickling stuff, Super Ford.

Sombody needs to send you a late rulebook - you knowing the various classes / restrictions would make your comments even more stimulating and specific!

Guaranteed this individual ain't Propster and CERTAINLY not 57 T Bird,
 poster child for every wannabee on the planet.

[WhizzbangK.C.]

No offense here at all, yet. In fact I'm finding your posts very interesting and supportive of a lot of my own thinking and experience.

I believe that you'll find you're not an isolated case on this board. A lot of us have very broad experience and education, and it's probably safe to say that the majority of us have dedicated very significant portions of our lives to mastering questions of speed and performance, in widely varied applications, and to the detriment of our personal lives and relationships. Most "normal" people don't seem to understand our obsessions, and we gravitate to those who do, ending up here.

I would still like to know in more detail what qualifies you to make the statements that you have with the certainty that you express in your writing. A lot of this stuff is based on research that was done with a certain set of parameters in mind, and may or may not be applicable to our varying applications.

Again, I find that what you have posted agrees with my own theories and experience, and supports a lot of the thinking that I do. I would like to know the source so that I can rationally rely on it as confirmation, rather than taking it at face value and investing a lot of resources only to find out that I was completely wrong and grasped confirmation that was also wrong without doing due diligence.

You apparently haven't been on this board long, so may not know that there has been more than one case of "experts" showing up and spouting their drivel without being involved in the actual sport or understanding the unique applications that we have to deal with.

Like I said before, forgive me if I'm wrong, and I hope I am.

Please identify yourself and give us something to hang our hats on in order to identify yourself and your experience.

Welcome to the board.

Thank you.

[Buickguy3]

  Superford 317,
     It doesn't matter who you are or what your qualifications are. Your statements and theorys are really stimulating. We have all grown accustomed to dealing with a government that spouts convoluted statements and it is up to us to sort out what fits our own situation. Don't take offense at our curiosity as to your qualifications. Please keep posting . I passed this string on a couple of days ago, with the caviat: " I think this guy's got it". Thanks for your participation.
  Doug 

[superford317]

i have hard data and research to back up everything i do and say and have studied for many years.

[wobblywalrus]

There are some things a fellow never forgets.  The film is threaded through the projector.  The lights are doused.  The hum and clatter of the Super 8.  It is time for another high skool drivers education movie.

Two black gentlemen my age are driving along the highway and happily chatting away the time.  The car is a mid 1950's American bomb.  The driver feels drowsy.  Sirens scream and the next scene appears.  The two fellow are alongside the road in body bags.  The car is upside down and the camera zooms in on a hole in the muffler.  A serious deep voice says "It was carbon monoxide from this leaking muffler that killed those two.  The exhaust was sucked up through the windows and cracks in the floor.  Proper exhaust system maintenance is critical.  The spent gases must exit beyond or alongside the rear of the vehicle."

This was good advice then and now.  It is dangerous technology to do anything different.  Do not bathe the bottom of the car in hot exhaust.

[superford317]

a better description with pictures so it can be understood more easily.

[maj]

SF you mentioned surface finish back a page or so,  what do you think of the "sharkskin"  now popular in swimming
and its effect on boundry layer ?

[SPARKY]

Intrested why can you make that guarantee?  Courious minds need to know

[Seldom Seen Slim]

SF317, this is Jon -- the owner of the site.  I've been looking at the back-and-forth between the others on the Forum - and you, and I notice that you're steadfastly hoarding personal information.  So be it since it isn't required for membership.  But since just about everyone else DOES tell us a bit of that data -- I guess you'll need to be prepared to accept whatever hassles they throw to you about asking who you are, and substantiating the information you list - such as your experience and education, whether formal or learned at the racetrack.

There's one thing that I do want from you, though, and it's yet another of the sore points that have developed over the past bunch of years.  That is the posting of material that may well be copyrighted, such as the drawings and sketches and articles and photos that you have or may soon post.  I can't, as the boss and owner, allow non-attributed material to be on the site lest I get hit with suits for infringement of copyright and so on.  Yes, I know that there can be allowances made for material that is posted only for information and not for profit -- but I'd like you to play on the safe side (for me) and tell us from what source any such material you list comes.  It's a requirement for others - and so it shall be for you.

Thanks.

Jon a/k/a Seldom Seen Slim

[Nexxussian]

Rex;

It may be a B-29 that I'm thinking of, but somewhere I read about using the engine exhaust gasses for additional thrust. I think there was an "augmentor tube" involved that sucked in air to add to the thrust.

Regards, Neil  Tucson, AZ

B-29s used exhaust to drive "Power Recovery Turbines" that recaptued power from the exhaust and delivered it (through a fluid coupler and a reduction geartrain) to the crankshaft, 700 HP worth at takeoff IIRC (so 700 of the roughly 3500 IIRC).

The closest I can think of an augmenter for round engine aircraft comes after the war with the DC-6 family (DC-6A, DC-6B, VC-118, C-118A, I don't recall all the designations) and some Convairs when equipped with the R-2800 Pratt and Whitney.

It (R2800) was equipped with an "ejector stack" exhaust system, on the aircraft in question.

On the DC-6s it fed into a cavity of the accessory section cowling (open on one side) that would appear to help with extraction of cooling air after it had done it's job.

In training early in my career of working on them, an instructor claimed that, on the Douglas,  it was worth 400 HP in Equivalent Shaft Horsepower at cruise (cruising between 18,000 and 25,000 feet, with 25,000 feet being the highest ceiling I remember them being certified to).


Since there are some here that are questioning sources, I am a certified A&P, untill recently I was employed at an airline (for over a decade) that primarily flies DC-6 type aircraft (the models I mentioned in parens earlier).

In the group of people I worked with were alot of folks that worked on R-3350 powered aircraft that were still using the PRTs,  it's an idea that won't leave me alone.

I know a Turbonique Drag axle would be illegal, I suspect that our frienly class chair wouldn't go for a power recovery turbine hooked to the diff either.

It would be interesting to try though, even if it was just for time.

Not nit pciking, I know manta22 mentioned he wasn't certain, so please don't take this as me "calling BS", 'cause I'm not.

He brought up a point I find interesting and I thought I would elaborate, with what I've learned over the years from both experience and what some call "book learnin".

[manta22]

Thanks for the input-- good info. If I remember right, that turbine engine power recovery system was called a "turbo compound" engine. I'm dredging up brain cells from when I was in junior high school on this stuff. 

Regards, Neil  Tucson, AZ

[donpearsall]

If a hot surface area on the vehicle makes it have less drag, funneling exhaust over the surface will not have much of an effect. The action and speed of the relative wind will not allow the hot gas to remain on the suface long enough, not to mention that there just plain is not enough of the gas to cover the vehicle.
A better alternative is just to paint the vehicle flat black. In the Bonneville summers, the sunny side of the vehicle can get up to 150 degrees (just guessing from touching the skin of my black car out there.)

Don

[hotrod]

A better alternative is just to paint the vehicle flat black. In the Bonneville summers, the sunny side of the vehicle can get up to 150 degrees (just guessing from touching the skin of my black car out there.)

A more important question is how hot is the black car skin at the 2 mile marker -- I would bet it is within a fraction of a degree of the outside air temp. Painting it  black also increases the ability of the skin to radiate heat, as black paint has higher emissivity in the infrared that other colors.

I strongly doubt that painting a car black is worth any measurable speed advantage. The cooling power of a 200+mph airflow far exceeds the radiant energy received from the sun.

It might make the car easier to find out on the salt but I suspect it is worthless for aerodyanmics. Next time you make a pass feel how hot that sun side of the car is when it comes to a stop. Or better yet put a cheap digital thermometer probe on a body panel not heated by exhaust or other internal heat source and watch how fast it cools as the car gets up to speed.

Larry

[grumm441]

I seem to recall a thread on compound superchargers somewhere on this forum
Very interesting stuff.

However, I'm not sure I would want to get in a black car out on a salt lake especially if the skin of said car was being heated by the exhaust. And of course there is what WW added

There are some things a fellow never forgets.  The film is threaded through the projector.  The lights are doused.  The hum and clatter of the Super 8.  It is time for another high skool drivers education movie.

Two black gentlemen my age are driving along the highway and happily chatting away the time.  The car is a mid 1950's American bomb.  The driver feels drowsy.  Sirens scream and the next scene appears.  The two fellow are alongside the road in body bags.  The car is upside down and the camera zooms in on a hole in the muffler.  A serious deep voice says "It was carbon monoxide from this leaking muffler that killed those two.  The exhaust was sucked up through the windows and cracks in the floor.  Proper exhaust system maintenance is critical.  The spent gases must exit beyond or alongside the rear of the vehicle."

This was good advice then and now.  It is dangerous technology to do anything different.  Do not bathe the bottom of the car in hot exhaust.

I don't think that would get through Tech
G

[jl222]

 
Nexxussian...turbo-compounding is allowed but puts you in supercharged class but it does not pressurize the engine...but you could use a super charger and gear a turbo or two back to the crankshaft [or?] like the Wright R-3350

 Rule book pg 48 section 4.ff

  We might catch up to what the aero guys were doing 70 yrs ago

               JL222