Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Mulry wrote:
Marc wrote:

i don't see how thrust vectoring solves the "not burning/deafening people behind you" problem. it might be a smaller cone of death but that's it.

Well, if you could angle the thrust slightly into a more vertical plane, you might place the angle of the "cone of death" so that it's basically shooting over the heads of the otherwise victims. 30 degrees? 45 degrees? But then the problem is that you're putting a lot of thrust in a wheelie-inducing vector, which will cause a significant understeer problem, which is already a consideration on a project like this. Plus the problem with the materials for the vector vanes and the controls. So yeah, it would be really really hard for thrust to work here. Not impossible, but difficult enough that running a driveline is probably a better idea. Just have to get over the small problems with that... smile

ahh, i see what you're saying. but you're somewhat underestimating the magnetism of such a car. I was shocked last weekend with how many people happily walked into the danger area. i had to kill the engine and be rude to a few people because of that. i want to avoid having to do that next time by keeping in consideration that people will just walk over to it while it's running.

27 (edited by mike944 2012-06-13 10:46 AM)

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

We've talked over email about the turbine engine a bit, so i know a bit about the engine you have.        The big problem with all of this "use thrust" talk is that the engine you have is not designed to produce thrust.   it's designed to turn a shaft.   For it to produce thrust, you'd have to connect that shaft to a fan capable of moving large amounts of air.   

as-is, and safety issues aside, you will seriously overspeed it before you produce any meaningful thrust.

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Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

mike944 wrote:

We've talked over email about the turbine engine a bit, so i know a bit about the engine you have.        The big problem with all of this "use thrust" talk is that the engine you have is not designed to produce thrust.   it's designed to turn a shaft.   For it to produce thrust, you'd have to connect that shaft to a fan capable of moving large amounts of air.   

as-is, and safety issues aside, you will seriously overspeed it before you produce any meaningful thrust.

oh, thanks. i did not know that a turboshaft moved significantly less air. i would have expected 300HP to produce around 400lbs of thrust or so, but i have nothing to base that on.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

mike944 wrote:

We've talked over email about the turbine engine a bit, so i know a bit about the engine you have.        The big problem with all of this "use thrust" talk is that the engine you have is not designed to produce thrust.   it's designed to turn a shaft.   For it to produce thrust, you'd have to connect that shaft to a fan capable of moving large amounts of air.   

as-is, and safety issues aside, you will seriously overspeed it before you produce any meaningful thrust.

Not to beat a dead horse (says the man who's probably about to beat a dead horse), but you could run a ducted fan off the power shaft to produce thrust that would not be spewing hot exhaust gases behind the car and duct the hot exhaust more vertically (limiting the cone of death recipients to birdies). I mean, theoretically, right?

This probably would still run afoul of Marc's rightful concern about the safety zone behind the car when running -- I share that concern, Marc, I was dumbfounded by the number of people who wanted to be right in line with the plane of the flywheel while the radial was running -- a/k/a the "catch some shrapnel with your forehead zone".

Pat Mulry, TARP Racing #67
https://youtu.be/qmf9JkedPR8

Mandatory disclaimer: all opinions expressed are mine alone & not those of 24HOL, its mgmt, sponsors, etc.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Mulry wrote:

Not to beat a dead horse (says the man who's probably about to beat a dead horse), but you could run a ducted fan off the power shaft to produce thrust that would not be spewing hot exhaust gases behind the car and duct the hot exhaust more vertically (limiting the cone of death recipients to birdies). I mean, theoretically, right?

Everglades airboat style?

Former chief proprietor and lead bad idea generator of Binford "More Power" Racing, 2010-2013: humbly self-proclaimed the best Chevy Beretta in LeMons history.

31 (edited by Marc 2012-06-13 11:16 AM)

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Mulry wrote:
mike944 wrote:

We've talked over email about the turbine engine a bit, so i know a bit about the engine you have.        The big problem with all of this "use thrust" talk is that the engine you have is not designed to produce thrust.   it's designed to turn a shaft.   For it to produce thrust, you'd have to connect that shaft to a fan capable of moving large amounts of air.   

as-is, and safety issues aside, you will seriously overspeed it before you produce any meaningful thrust.

Not to beat a dead horse (says the man who's probably about to beat a dead horse), but you could run a ducted fan off the power shaft to produce thrust that would not be spewing hot exhaust gases behind the car and duct the hot exhaust more vertically (limiting the cone of death recipients to birdies). I mean, theoretically, right?

This probably would still run afoul of Marc's rightful concern about the safety zone behind the car when running -- I share that concern, Marc, I was dumbfounded by the number of people who wanted to be right in line with the plane of the flywheel while the radial was running -- a/k/a the "catch some shrapnel with your forehead zone".

I bet the ducted fan setup might be possible to run through tech with appropriate guards in place. if the volume of air is significant enough to dilute the turbine exhaust heat down to a resonable temperature i bet you could even blend it together. but i just don't feel that this is the kind of drivetrain i want to build. someone else can carry that torch.

I'm glad i'm not the only one that noticed where people wanted to stand. most reacted with a "oh, thanks for letting me know" kind of reaction. some were offended when i asked them to move. i don't get it.

32 (edited by Buzz Killington 2012-06-13 11:19 AM)

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

This is Amurica, buddy.  You keep yur Commie pinko safety concerns to yourself...did our boys worry about engines flying apart when they stormed Normandy?  Well did they?  wink

3800GK wrote:

Does the turbine need to stay at a constant speed to stay reliable/intact?

If there is one thing turbines hate (other than ingesting solids), it's being throttled up and down.  They are happiest at constant RPM.

mike - Schumacher Taxi Service
12+-time loser
"Winner" - We Got Screwed, NJMP '11

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

obsolete wrote:

Everglades airboat style?

This. Plus finding the fan stuff would be relatively easy since there's an entire industry building those. And somebody has to be safety testing the fan cage (right?), which would make it easier to pass tech.

Pat Mulry, TARP Racing #67
https://youtu.be/qmf9JkedPR8

Mandatory disclaimer: all opinions expressed are mine alone & not those of 24HOL, its mgmt, sponsors, etc.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Marc wrote:
mike944 wrote:

We've talked over email about the turbine engine a bit, so i know a bit about the engine you have.        The big problem with all of this "use thrust" talk is that the engine you have is not designed to produce thrust.   it's designed to turn a shaft.   For it to produce thrust, you'd have to connect that shaft to a fan capable of moving large amounts of air.   

as-is, and safety issues aside, you will seriously overspeed it before you produce any meaningful thrust.

oh, thanks. i did not know that a turboshaft moved significantly less air. i would have expected 300HP to produce around 400lbs of thrust or so, but i have nothing to base that on.

Ok, this is a bit simplified, but the principle is here.        For a conventional engine, like what's on an aircraft, that shaft is basically connected to a fan (the only thing people see when they look at an aircraft engine) , and it's the fan that produces like 90% of the thrust.   There is some thrust produced by the core (which is really what you have), but its minimal.     For a stationary engine, there is no need to even produce a minimal amount of thrust, so it doesn't.   Yes, you will get some air rushing out the exhaust, but it's near atmospheric pressure, and there's no nozzle, so you don't get any meaningful thrust.

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Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

mike944 wrote:

Ok, this is a bit simplified, but the principle is here.        For a conventional engine, like what's on an aircraft, that shaft is basically connected to a fan (the only thing people see when they look at an aircraft engine) , and it's the fan that produces like 90% of the thrust.   There is some thrust produced by the core (which is really what you have), but its minimal.     For a stationary engine, there is no need to even produce a minimal amount of thrust, so it doesn't.   Yes, you will get some air rushing out the exhaust, but it's near atmospheric pressure, and there's no nozzle, so you don't get any meaningful thrust.

so i don't have to worry about vertical exhaust past the rear wheels lifting weight from the front wheels. good to know!

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Marc wrote:
Mulry wrote:

...I'll keep wandering out here in la-la land and see if I can think up anything else that exceeds even your tolerance for teh crazy. smile

crazy ideas sometimes cause good ideas to come out smile what drives me crazy is hearing the same idea a million times without any understanding of why it cannot work smile

anyways, the thrust idea is just out due to the safety aspect above and the noise restrictions. part of my noise handling will be to redirect the exhaust vertically and you can't do that when you need the thrust.

one thing that could work is to use hot air capable jet air starters (not all of them use bleed air) and just put the starters as wheel motors. they seem to be 90-150hp motors and could be driven from the exhaust gasses.


So why don't you just make this sucker 'lectric?  Here's an eBay listing that's just over $100 for an all-electric Escort SW!!1!!
http://cgi.ebay.com/ebaymotors/All-Elec … 33776ba2d4


I kid, I kid...

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Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Saw this one in the Petersen Museum years ago.  Seems front engine rear drive is a much easier packaging, unless the engine blows:

http://www.oldcarsweekly.com/news/hobby … in_hot_rod

https://scootinoldskool.files.wordpress.com/2012/06/lemay_hotrod_turbine.jpg?w=600

Constructor/Owner/Driver - Billy Beer Ford Futura

38 (edited by Buzz Killington 2012-06-13 11:35 AM)

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Mulry wrote:
obsolete wrote:

Everglades airboat style?

This. Plus finding the fan stuff would be relatively easy since there's an entire industry building those. And somebody has to be safety testing the fan cage (right?), which would make it easier to pass tech.

http://www.validate.net/turbine/

Same turbine and all.

mike - Schumacher Taxi Service
12+-time loser
"Winner" - We Got Screwed, NJMP '11

39 (edited by lemonphil 2012-06-13 11:45 AM)

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

I second the "copy chrysler" idea.

The power turbine was connected, without a torque converter, through a gear reduction unit to an only moderately modified TorqueFlite automatic transmission. The flow of the combustion gases between the gas generator and free power turbine provided the same functionality as a torque converter but without using a conventional liquid medium. Twin rotating recuperators transferred exhaust heat to the inlet air, greatly improving fuel economy. Varying stator blades prevented excessive top end speeds, and provided engine braking on deceleration.

They used an automatic transmission, I'm not sure about that. They had to have had some sort of geared reduction?
I bet you could email leno's garage and maybe they'd provide some info, or most of it is probably online.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

lemonphil wrote:

has chrysler been mentioned? They produced a few turbine cars

The power turbine was connected, without a torque converter, through a gear reduction unit to an only moderately modified TorqueFlite automatic transmission. The flow of the combustion gases between the gas generator and free power turbine provided the same functionality as a torque converter but without using a conventional liquid medium. Twin rotating recuperators transferred exhaust heat to the inlet air, greatly improving fuel economy. Varying stator blades prevented excessive top end speeds, and provided engine braking on deceleration.

They used an automatic transmission, I'm not sure about that. They had to have had some sort of geared reduction?

yup, gear reduction and a free power turbine. i don't have a free power turbine which complicates things but also makes the motor and control a bit simpler. i don't have to worry about overspeeding the free turbine.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Marc wrote:
lemonphil wrote:

has chrysler been mentioned? They produced a few turbine cars

The power turbine was connected, without a torque converter, through a gear reduction unit to an only moderately modified TorqueFlite automatic transmission. The flow of the combustion gases between the gas generator and free power turbine provided the same functionality as a torque converter but without using a conventional liquid medium. Twin rotating recuperators transferred exhaust heat to the inlet air, greatly improving fuel economy. Varying stator blades prevented excessive top end speeds, and provided engine braking on deceleration.

They used an automatic transmission, I'm not sure about that. They had to have had some sort of geared reduction?

yup, gear reduction and a free power turbine. i don't have a free power turbine which complicates things but also makes the motor and control a bit simpler. i don't have to worry about overspeeding the free turbine.

Caught me mid edit.

Thanks for the explanation, I look forward to following your progress.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

no problem. also i may discover the further i get into this that a turbine without the free power turbine is more trouble than it's worth. i send off an e-mail to get a price on this one just so i know: http://www.avonaero.com/allison.htm

317SHP (Shaft Horsepower)
136 lbs
6000RPM output
designed to be throttled instead of a generator application
0.70lb of fuel per SHP per hour
free turbine output that could be used to drive a much simpler transmission (even a manual trans)

if we compare that fuel efficiency of regular engines: http://en.wikipedia.org/wiki/Brake_spec … ft_engines

it'll get about 2/3rds the fuel economy of a gas engine. certainly not that big of a deal. we'd probably end up using double the fuel on the track since the reduced throttle fuel usage is much worse than the difference at full throttle.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

I don't know if you can glean any useful info from this, but Rover made prototypes of a jet car in the '60s. The T4 was front engine, front wheel drive, so the packaging might a bit more relevant to your rear engine, rwd setup than the turbine Chryslers. 

http://dayerses.com/rover-t4.html

Nathan

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

I'd definitely stick with some sort of shaft drive. Relying on thrust propulsion is going to cause all sorts of problems in my mind... poor low speed performance would be my main concern, but also thrust effecting other cars, stirring debris, etc.

The good news is that the Tiernay already has a healthy gear reduction, but some caution should be exercised on turning up the power as the gear reduction may not be designed for it. After all, all it has to turn is a 10KW generator.. or about 15 hp once you factor in some loss.

As far as reduction down to the automotive transmission goes, I suggest that your primary reduction be some sort of belt drive. There are serpentine drives out there more than capable of transferring at least 50 hp, but you'll likely have to pay attention to a maximum belt velocity when sizing pulleys. I'd be skeptical if a cogged belt could handle the required speed demands, but an option there would be to use a timing belt and pulleys from an automotive application.  However, with pulleys from most engines, you'll be limited to 2:1 reduction per stage.

That said, one of the biggest things to take care of with a belt drive is ensuring that the input and output shafts can handle the lateral forces caused by the belt tension (both pretension and tension on the tight side of the belt under load).

Otherwise the only other option is going to be a gear drive which is going to require some considerable precision for those speeds.

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Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

Marc,

First off, awesome work on the last version and I can't wait to see how this one turns out.

Second, some thoughts on using a 4x4 transfer case for the speed reduction.

The Jeep Wrangler Rubicon uses the NV241OR, a massive beastly chain driven transfer case with a 4:1 reduction in low range.  This sounds perfect, until you look at the RPM you'll need to run through it.

Jeep warns drivers to never exceed 25MPH in low range, and I'd assume that's due mostly to heat buildup issues, but I'm sure there's a limit on the rotational velocity that the internals can handle as well.  The Rubicons this transfer case comes with have 32" tires (650 revs per mile, or 8.12 feet per rev) and at a worst case (for RPMs at the shaft) 4.10:1 diff gears.

If we do some math that works out as follows: 25 mph / 60 min = 0.417 mpm * 5280 ft = 22 fpm / 8.12 ft = ~270 axle revs per minute * 4.10 axle ratio = 1110 output shaft rpm * 4 t-case ratio = 4440 input shaft RPM.

So you have a limit of about 4400 input RPM and 1100 output RPM, if you follow the manufacturer limits.  I'm sure with a big external cooler you could improve that a bit, but I doubt it would survive for more than a few glorious seconds at 10 times that speed.

Now this is only one transfer case out of many on the market, but I'd imagine that most others are pretty similar.

I'm of course not saying this to discourage you from trying, but IMHO the more information the better.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

I used to do quite a bit of offroading, I've dealt with many transfer cases and have several in my shop already.

bearing RPM ratings will become the major issue. but if i rework the case slightly, it's not hard to find bearings that can deal with 12,000RPM speeds as long as the oil is kept cool.

also, i just need 3:1, not 4:1 and many transfer cases are 2.7-2.8:1 which will likely be close enough as far as i'm concerned for this.

of course, that's where that Alison 250 turbine would shine. it's output is rated for the turbine's power (which may not be the case with this current one) and it only spins 6000RPM which is perfectly acceptable to shove right into a normal automatic transmission and all that's needed is some logic to actuate a brake on the output to not break the trans when shifting from neutral to drive or reverse.

it might make the turbine more expensive but it may save headaches and much work on the other bits. we'll see...

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

My Uncle Dave was involved in the Rover BRM project in the early 1960s, sadly he died about ten years ago, so I cannot call him up and ask for any secrets and the Wiki entry is somewhat sparse....

http://en.wikipedia.org/wiki/Rover-BRM

However it came 7th in class and 10th overall at Le Mans in 1965.

The MR2 needs painting BRG and you need to reserve #31 for it when you get it to the track.....

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

maxn wrote:

My Uncle Dave was involved in the Rover BRM project in the early 1960s, sadly he died about ten years ago, so I cannot call him up and ask for any secrets and the Wiki entry is somewhat sparse....

http://en.wikipedia.org/wiki/Rover-BRM

However it came 7th in class and 10th overall at Le Mans in 1965.

The MR2 needs painting BRG and you need to reserve #31 for it when you get it to the track.....

even without this project i'd love to buy someone like that a beer and just talk about the projects smile

When i do get time after the fabrication is done the car will get a very nice paint job. I've got 2 people in town interested in helping me with that.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

wow, that Allison turbine is $26k. and that right there explains why i may need to find a way to work with the smaller turbine.

Re: version 3.0: The MR2 gets a gas turbine engine (Project Outline)

I think that you are going to have pretty inescapable problems trying to connect a turbine engine to the ground through a $500 crapcan. The free turbine in lieu of torque converter that the Boeing hotrod guy used was pretty much as good as such a thing is going to get.

Trying to get power out of a turbine engine is a challenge under even the best circumstances. The small ones especially are designed to run within limited RPM ranges and limited power output levels. Outside of those ranges they tend to cook turbine blades, and they also encounter harmonic resonances that cause fatigue, cracking, and premature separation of important bits.

If this was my assignment, I think that I would hunt up an old GPU trailer complete with T-62 turbine and generator, and cram the trailer's contents into the car atop the electric motor that drives the transaxle. Then it becomes a wiring problem. What could possibly go wrong?