T58 pt.8: the Power Turbine

A quick look at the propulsion system of the race boat, which is powered by the Power Turbine.
We also get a chance to see how the engine transmits those 1200Hp to the PT.

[@scubasky]

Magician swagger at the end! love it lol

[@johnm400uk]

When you said 'your going to see the coupling that transmits 1200 HP' i knew straight away there was no coupling!! Full marks to me for listening to what you taught us in your other videos!! :-)

[@garyh.8082]

Worked on a later variant in the Marines. It was the General Electric T58-GE-16 model. Put out 1875 shp. They were used in the Boeing CH46E Helicopters. 3rd MAW, MALS-16 Tustin California, 91-95.

[@AgentJayZ]

All of the racers are looking for that model...

[@AgentJayZ]

Yes, but the power available at idle is so low that the internal friction of the water jet pump keeps it from turning. If the engine was still in a helicopter, then "flight idle" is about 84% rpm, and there is maybe 50Hp on tap, but the engine is able to quickly respond. "ground idle" is around 60% rpm, and the power is essentially zero. The gas pedal in the boat is actually a fuel control power setting, and has a detent at 84% rpm. Below that detent the waterjet does not turn.

[@robertsamspon4232]

idle should be 56 =or - 3% based on temp's. do you still run the tach gens " NG and NF"? I would be interested to know what the temp is on your wide open blast, and it should not exceed 750c. been around these engines in helos for few years and never seen one in a boat but its badass!!! that drive on the engine, looks like what they had on the UH-1F, or a modification of that. lol Great info, yall do some awesome stuff!

[@ccaptnkid]

@@robertsamspon4232 These engines were also used on the CH3 (Jolly Greens). I worked on them both state side and in Vietnam

[@flyonbyya]

Think of all the brains, effort and money that went into the development of those extraordinary machines that have yet to be improved upon...70 years on!

[@AgentJayZ]

We need to avoid getting confused here, because a lot of terms mean similar but different things. That said, the exhaust of the engine means the exhaust coming out the back of the PT. There is quite a bit of leftover heat, but very little kinetic energy. Because of the design of the exhaust outlet, there is no thrust at all, and it is only slightly more than a gentle breeze. Hot, though!

[@AgentJayZ]

You are one of the few, the proud... the Jet People !

[@AgentJayZ]

There are some engines designed that way. The disadvantage is the load is always connected to the engine, and that can make starting up very difficult. With a turboprop, the load is variable via prop pitch, so it works well, as in the Garrett TPE331. For a helicopter, even at zero pitch, there is a lot of mass and rotational inetria of the main rotor system. This would all have to be spun up to min rpm by the starter. Both types of engine are equally efficient.

[@robertsamspon4232]

on the S61, H3, and ch46, they dont spin the rotors when they state this engine. Being a free power turbine, they have the rotor brake on holding the rotor system from moving. I remember reading somewhere it took 36 ftlbs at idle to hold the high speed shaft connected to the power turbine. The electrical starters on these engines suck, and draw a huge load, but they hydraulic versions are awesome.

[@corystansbury]

Loved all of these videos, Jay. Fantastic attention to detail. Thanks.

[@AgentJayZ]

Even though it may appear that the main rotor is speeding up with the engine as it starts in a helicopter, it is only coupled by the gases passing thru the power turbine, and so the core, or gas generator can more quickly gain rpm during startup than if everything was on one common shaft. ... Most helicopters, that is !

[@AgentJayZ]

Planetary gearsets are usually very good, but expensive. I actually have not seen the inside of the speed reduction gearbox, because that isn't part of the engine ( yes it is bolted to the engine, but it's a separate thing. )

[@shaithesm0ck]

nice hand movement during the "nothing but hot air" ;)

[@AB-80X]

Aah, c'mon Jay. Looked forward to see the PT in this one. The PTs are not often in the vids, so let's see them when the opportunity is there. No matter the part of the engine package, if it whirls around really fast. I like it:-)

[@bagelboi66]

"Nothing but hot air" is a good answer for the folks who come by here knowing more than the channel owner.

[@motormouser]

You forgot the "Tadaahh!" Great vid! :-)

[@cganz1234]

I'm very familiar being an old PT6 guy! Keep the great videos coming!!!

[@mekman]

Cool, that's exactly what I was wondering. Thanks for the explanation and clarification.

[@AgentJayZ]

I don't know why your comment was marked as spam... I marked it as not spam... You would probably really enjoy reading "the Jet Engine" published by Rolls Royce. It's one of my personal favorites.

[@66tbird1]

Great series, Thank you

[@jdmk20aek]

jeeze i love these videos !!!

[@clockman47]

THANK YOU.

[@horizonflyer9]

Wow I wouldn't have guessed that the power turbine wasn't connected to the gas generator. So does that mean that a gas generator has its own turbine blades to keep itself running?

[@jossi166]

Awesome video. How did you end up fixing the problem with the flange for the auxiliary stuff that kept braking?

[@scottmarshall6766]

I know this is pretty old, (Been following for a few years, but I missed this series), but I have a question. How is the power turbine bearing(s) oiled? Is there a set of external oil lines for pressure and scavenge, or does the output stage have it's own oiling system driven by the output reduction gearset? Or is it something else entirely? Thanks for all the great videos Jay, I've learned a lot from your videos, you're a good teacher. I tell people you are the Turbine version of Abom79.

[@AgentJayZ]

The PT on the T58 and the reduction gearbox attached to it are both included in the engine lube system. All three of those assemblies form what would be called the engine for a helicopter that uses the T58

[@mekman]

I was half expecting a wee man to to be in there with a bunch of levers and gears :^) I'm curious how powerful the actual exhaust is in that setup, ie. how much of the energy is not transferred to the turbine. Does it come out as a significantly forceful jet or more of a gentle breeze?

[@maxsu8795]

Lovely~

[@AgentJayZ]

Yeah, it can be either a verb or a noun...

[@slamdvw]

"Nothing but hot air..." insert political joke here. Neat little engine. I think you covered it, but what is the PT speed? Provided enough fuel, I am assuming 100% duty cycle? Thanks for sharing.

[@horizonflyer9]

I'll give it a look :)

[@saxonlight]

David Copperfield should be worried right about now.

[@snaproll94e]

Of course, it's turbine powered and fast, quiet too, you can hear the slicks screech as they slip well into the run.

[@rk81oman]

@johnm400uk Thats exactly the same i thought when I heard the word "Power Turbine": Which Coupling?! Thanks AgentJayZ for turning us into "Jet People" :)

[@AgentJayZ]

And "spool" ? There are no spools in power turbines. It is a techincal word, meaning a drum-like structure to which more than one stage of blades are attached. It is also a slang term meaning a rotating part of a turbine engine. If used the first way, answer is no. If used the second way, then it's like saying right handed side shoe instead of right shoe. Either way... no. Not for me, anyway. Cheers!

[@wlaukaitis]

So it kind like a torque converter in a car.

[@TalksWithDirt]

I just figured out the solution to the energy crisis. Instead of microphones in front of politicians, let's have them speak into power turbine units hooked up to generators.

[@fryncyaryorvjink2140]

I want to put a power turbine in my car! Ideally this one, but realistically keep it about the same power as it already is, ~200hp. Ok maybe 300 So the power turbine drives the water pump through a belt and the alternator is for other functions?

[@AgentJayZ]

The power turbine drives the water jet pump through the output shaft. The alternator is indeed for other purposes, like charging the batteries.

[@timmoreebesa6973]

HI COACH, I CONNECTING THE OUTPUT DRIVE TO THE MAIN (COMPRESSOR) SHAFT OF THE ENGINE LIKE THAT OF THE T56, AND CONNECTING THE OUTPUT DRIVE TO THE POWER TURBINE LIKE THAT OF THE T58, WHICH CONNECTION WILL GIVE MORE POWER TO THE OUTPUT SHAFT TO DRIVE THE MECHANICAL LOAD?

[@AgentJayZ]

Neither. Please stop yelling.

[@williegillie5712]

I can see and hear that turbine spooling up to those high rpms in that boat. Wonder why they can't get a turbofan in airliners to rev without all that hammering noise. I can tell they want them turbofans backed off as soon as they can to reduce vibration. Do ya think the newer speed reduction turbofans are gonna fix the problem? I've seen more then a few videos of them things coming apart with a loud bang. Can't believe they still use them.

[@incompressible01]

Is there a way to stop the impeller from spinning - some kind of braking system somewhere ?

[@AgentJayZ]

Some of the boats use a rotor brake, which can keeo the pump from turning, bit it has to be applied before engine start. Once the PT is turning, the brake can't stop it.h

[@AgentJayZ]

Kind of like saying right side shoe, instead of just right shoe.

[@Venom2U]

Wouldn’t it be more accurate to say there’s no connection between the gas generator and a “free spool” power turbine?

[@sabamacx]

How is the gas generator started?

[@horizonflyer9]

Sorry... very new to turbines, always known more about internal combustion engines... I'm always wanting to learn more though. Thanks anyway

[@AgentJayZ]

No, because a power turbine is always a free turbine. I guess the full name is free power turbine, but nobody says free, because that is implied by the word power.

[@Themayseffect]

Are these engines more or less efficient than a piston engine of similar power?

[@AgentJayZ]

Video series called Your Questions Answered. I have probably answered it there. Let me know If I haven't OK?

[@Themayseffect]

AgentJayZ you have several of those videos. How am I supposed to know which one... 🤔. To be specific I meant with relation to powering boats. Not in general.

[@AgentJayZ]

The answer is not specific. It's general. And it's long enough to not fit in a comment box. So I discuss it several times in that playlist. If you are not interested enough in turbine engines to look through a playlist for the answer I made just for this exact question, then I guess you won't find it.

[@sdavies45]

but probably not many of us do know more than the channel owner in this case. I know I don't. Do you?

[@snaproll94e]

If you haven't seen this dragster, I promise you'll like it and appreciate the engineering. kzbin.info/www/bejne/h6POeKJ_e6-mrpo

[@deSloleye]

Spool is a verb?

[@dwetzel22]

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