68 Indy turbine lotus question - PeachParts Mercedes-Benz Forum

t walgamuth · #1 06-25-2015, 10:54 AM

I saw today one is coming on the market soon. Among the comments about it was no transmission and no cooling system. I'm not sure how the power is transferred the wheels without a transmission and even less sure how it would not need any cooling system? Surely the motor gives off heat?

tbomachines · #2 06-25-2015, 11:14 AM

Trading the formula ford?

I could see a direct shaft to the rear diff with a significant reduction gear and clutch involved. Operating rpms of gas turbines can be pretty wide (although obviously there is peak power and efficiency somewhere). Also probably air cooled, imagine most the heat goes out the back as exhaust and there aren't too many moving parts that need to be cooled beyond the intake air.

Sent from an abacus

MTI · #3 06-25-2015, 11:18 AM

The motor used in the Lotus was designed as a power generator turbine, so there was a driveshaft. No transmission, since the torque range was huge. Cooling? Air cooled via the turbine discharge.

DieselPaul · #4 06-25-2015, 11:25 AM

It's already been said, but what they mean by "no transmission" I gather is no gearset. They used a torque converter to transfer the power and they were otherwise direct drive.

P.C. · #5 06-25-2015, 11:45 AM

https://en.wikipedia.org/wiki/Turbine_blade

t walgamuth · #6 06-25-2015, 01:04 PM

I'd have to imagine there are some reduction gears somewhere even if no shifting is needed. don't turbines turn some 30,000 rpm or so?

Idle · #7 06-25-2015, 11:11 PM

The STP Indy turbine had a transmission. The reason they led the race and then lost it was because the transmission imploded with five laps to go.

The turbine was banned at Indy since the driver had a habit of getting too close to the other drivers with his exhaust port and frosting their visors. I am sure this was just an accident, but it was a real thing so don't stand too close to the exhaust port.

t walgamuth · #8 06-26-2015, 05:15 AM

Quote:

Originally Posted by P.C.

https://en.wikipedia.org/wiki/Turbine_blade

Very interesting. Thanks!

t walgamuth · #9 06-26-2015, 05:25 AM

Quote:

Originally Posted by Idle

The STP Indy turbine had a transmission. The reason they led the race and then lost it was because the transmission imploded with five laps to go.

The turbine was banned at Indy since the driver had a habit of getting too close to the other drivers with his exhaust port and frosting their visors. I am sure this was just an accident, but it was a real thing so don't stand too close to the exhaust port.

I think its generally agreed it was banned because it was too fast. The hot exhaust was one of the things the other teams whined about. And it was not actually banned they just reduced the allowable intake size enough to make it too slow from lack of power.

The first year they ran the turbines was '67. That was the one with the engine beside the driver. It ran on ordinary jet fuel which is pretty close to diesel in its makeup. They ran it in practice and in the race. They also were able to run any tire they liked so they ran rear (bigger) tires on the front for more grip.

The intake was reduced for 68 enough it was thought to make them uncompetitive. The cars were also restricted to using four front (smaller) tires... but Lotus was engaged to design a newer lighter car with better aero. And it was still dominant.

But they ran white gas in the race for better fuel economy and it gave them some trouble, causing the cars to flame out and die on resumption of racing speeds after a yellow light.

Lotus ran a version 56B of the same car in F1 in 1971 in a few races. It was competitive in races that were rainy, but it was too heavy and too slow in dry conditions.

t walgamuth · #10 06-26-2015, 06:08 AM

The Lotus 56 which crashed at Indy in practice killing Mike Spence was shipped back to England where it was eventually reconfigured to be run in F1. It added fuel tanks on the sides (seen as bulges in the pictures) and nose wings and a spoiler on the back. It proved fast in practice and in at least one race which ran in rain.

KarTek · #11 06-26-2015, 01:31 PM

Turbines come in a variety of flavors. Generally, there are the "suck and blow" types that generate power by producing thrust and there are the types that are used to directly drive loads like helicopter rotors, electrical generators and in this case, wheels of a car.

The types that drive loads directly can be split into two groups (again generally): The type with the compressor and turbine shaft coupled directly to a gearbox and the load and the other type that has the compressor and turbine shaft with a separate turbine and shaft which is connected to a gearbox and again to the load.

For the second example, think of a fan blowing on another fan and the power from the second fan is coupled to the wheels.

So what does that do for you? In the case of an electric generator, you have a load that needs to run at a constant speed with no requirement to stop and start or operate over a wide variety of conditions. So, the direct coupled turbine is adequate for this purpose. Some helicopters and turboprops also run direct coupled turbines because the propellers and rotor blades take care of varying the load and power output of the turbine.

In the case of a car that has to run from a dead stop to a wide variety of speeds, the uncoupled turbine is ideal. Basically, you can start the turbine with the output shaft at a dead stop, then apply more power and the car will move forward. In this instance, there is a much wider potential for output speed and power than in the direct coupled example. In an automotive application, it makes it easier to put a simple 1 or 2 speed transmission in a car that helps cover any gaps in the turbine output. In the case of an Indy car, it stops, speeds up and runs in a fairly narrow gap of speed so extra speeds were probably not needed.

Here's a good picture of a two stage turbine. You can see the second stage on the right that's not directly connected to the main turbine/compressor shaft.

Hope that kind of answers your question.

Idle · #12 06-26-2015, 01:31 PM

Quote:

Originally Posted by t walgamuth

I think its generally agreed it was banned because it was too fast. The hot exhaust was one of the things the other teams whined about. And it was not actually banned they just reduced the allowable intake size enough to make it too slow from lack of power.

The first year they ran the turbines was '67. That was the one with the engine beside the driver. It ran on ordinary jet fuel which is pretty close to diesel in its makeup. They ran it in practice and in the race. They also were able to run any tire they liked so they ran rear (bigger) tires on the front for more grip.

The intake was reduced for 68 enough it was thought to make them uncompetitive. The cars were also restricted to using four front (smaller) tires... but Lotus was engaged to design a newer lighter car with better aero. And it was still dominant.

But they ran white gas in the race for better fuel economy and it gave them some trouble, causing the cars to flame out and die on resumption of racing speeds after a yellow light.

Lotus ran a version 56B of the same car in F1 in 1971 in a few races. It was competitive in races that were rainy, but it was too heavy and too slow in dry conditions.

Good info. History is history and you can't know too much of it.

MTI · #13 06-26-2015, 01:57 PM

t walgamuth · #14 06-26-2015, 02:08 PM

Very cool drawing MTI! Thanks for sharing it with us. I suppose the car ran the uncoupled turbine. That drawing btw is of the 56B.

t walgamuth · #15 06-26-2015, 02:11 PM

I was there BTW in '68 when they qualified. I loved it when Graham Hill put it on the pole, then Joe Leonard came out and beat his time....I'm like "WTF is Joe Leonard?" He was pretty new to the Indy scene but had been a motorcycle champ, IIRC.

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