Turboprop or Turboshaft 

Again, I am overshadowed by your experience and knowledge!

@@AgentJayZ I was still a new boy in the design office at the time (around 1967-8), so they didn't let me anywhere near the turbomachinery. I was on the fuel systems section and my small contribution on the RM1A was a mounting bracket on the left-hand gearbox, carrying some sort of valve and a junction block. That might be an RM1C on test and I didn't get a glimpse of that area.

Thank you so much I was just going to ask this! It seemed odd to leave so much power turbine in the gas flow when it's only load is the LP compressor and was going to ask if you removed some before fitting the PT. It's really cool to see a solution like you've described. Is it much a coincidence that the LP turbine could be so neatly divided into LP and PT stages or are the stages designed in a modular fashion?

​@@deSloleye No, as far as I'm aware,, there was no such intention when the aero Tyne was designed under the leadership of Lionel Haworth, with whom I once had a fascinating chat over lunch. In the aero engine, all three discs of the LP turbine are held together by a ring of through bolts. I think that it was a fortunate coincidence and, as I recall, it wasn't even necessary to restagger either the LP1 NGVs or the LP1 blade, to tweak the power split. Even if it had not been the case, it is probably all that would have been required. A new LP2 NGV was required to become the PT1 NGV. However, this was not for any aerodynamic reason. A new, wide chord NGV was required because a new bearing was required behind the single-stage LP turbine and at the front of the two-stage free power turbine, in a new bearing housing arrangement, which the new NGV supported.

I am lucky. Also, we have no secrets, and everyone is proud of their work.

@@AgentJayZ That IS rare indeed

@@LateNightHacks G'day, Um, well, I may be wrong, but I doubt if a Civilian Gas-Turbine Engine Workshop catering to the Warbird, Racing Jetboat, and Industrial & Marine Generator Industries is ever likely to be dealing with anything which has been on any "Secret Lists" for 50 years. And as far as Jay's Boss is likely to be concerned (always assuming that it isn't all his own personal Workshop & Business ?!), then every time Agent JayZ posts a Video that's FREE ADVERTISING, Globally, for Jet City - generating interest, increasing public awarwness & thereby perhaps attracting new customers... (?). So, unless Agent JayZ drops a really serious "Clanger" and says something wildly erroneous..., or he posts a Video showing & explaining the innards of something which is STILL "Classified as 'Secret Squirrel Only !'...", then ; it's ALL Good (Publicity)... Let's face it..., if one watched every Upload on this Channel 3 times that would not enable one to attempt to refurbish an Old Jet Engine, even if all the Required Tools & Spare Parts came with the Project. An Apprenticeship is required, for all the critical Word-Of-Mouth tips, & the Monkey-See/Monkey Do (repetitious) bits of the Job to be installed within one's Worldview.... At least that's my impression. Such is Life, Have a good one... Stay safe. ;-p Ciao !

Nice. Will watch.

Thanks for sharing your valuable expertise. Just a query as you mentioned that vanes used to rotate.... Was it a hydraulic mechanism? To me it looks like as they acted as IGVs... However, my question is about vane rotation... Thanks for sparing your valuable time.

@@cck0728 It appears that I have misled you. The usual convention in gas turbine engines is that blades rotate and vanes are fixed. However, the projections on the face of a centrifugal compressor impeller are frequently described as vanes: it was this terminology to which I was referring.

@@grahamj9101 Thanks for your clarification. Please keep us educating with your valuable expertise.

Yeah I'm surprised that he hasn't shut down due to jealous people talking shit.

Your oversimplification is making the professional millwrights who made this all work laugh out loud... at you.

@@AgentJayZ Haha, I have no doubt what so ever about that.

Got videos of it...

@@AgentJayZ Thought you had! From what I read, it was originally for static use then S&S did the refurb on it when it was decided to get the F-104 to flyable condition. But I only quickly read the piece.

This is yet another example of the difference in terminologies between Derby and Bristol. Going back into history, the Avon and for every subsequent Derby engine that had such valves, they were known as a bleed valves. I worked on the Industrial/Marine Proteus (which was originally the Bristol Proteus turboprop) as a very young designer and that had blow-off valves (BOVs).

My recollection is that the cardan shaft connecting the power turbine to the marine gearbox had membrane couplings at both ends, but it's a long time ago .....

Centrifugal compressors make a totally different noise, as compared to axials.

Do you even watch?

Recent videos here show just that. Scroll through them and you'll see everything you ever wanted to see

The only difference is that It can be intermittently operated, and when operating, it only extracts a portion of the exhaust energy, leaving a significant amount left for the rest jet nozzle to convert into thrust. I don't work on that engine, so you know more than I do about it.

Honda CTX 1300 V4. Intercity comfort missile that I use as a long distance sport tourer.

@@AgentJayZ Sweet! I'm on a VFR so I know the charm of the v4 comfort missile. Love your channel.

VFR is a bike I have always wanted, but never have owned. My Honda V4 is great, but only revs to 7 grand.

I don't understand what you are saying, so I can't answer.

@@AgentJayZ my bad. You gave the answer in other videos. Thanks!!

Its not the ignitor box. Its a chamber into which all of the bearing sump vents are connected.

@@AgentJayZ Thanks for the clarification.

The air dyno, which is a compressor section from a J79, has it's own oil pump, reservoir, oil filter, oil cooler, and vibration sensor. It will be very happy to run as long as we ask it to.

When you have to clean them, it's depressing to know how many there are...

We measure the torque directly off the engine's output shaft, so we don't have to estimate losses in the gearbox. We are using an exhaust manifold from a different model of turboshaft engine, slightly modified to fit our purposes.

@@AgentJayZ Thanks, good stuff, you really do a great job.

We've got real millwrights on our crew, and they handled all the intricate setup.

I actually live a bit close to there

The amount of air going into the air dyno is the same as for a J79 at something around flight idle. The rear of the air dyno is an open midframe, and the compressed air does just get released into the room. Lots of noise and heat. If any process needed a 20 thousand Hp air compressor, this would be a good way to make that happen. I don't know of any such installations.

industrial turbo commpressors are used in some cases for large plants, i know of a refinery near me that has one. no idea what kind of power this compressor is also they are used in some blast furnaces to force air through the coke and iron ore to fan the fire

We've had a few. They are know as O.E.L. 7s and have a cast, rather than fabricated front frame.

The natural gas pipeline compressors are large centrifugal units.

Yes it is supplied with oil from a separate pump.

I have done that in a video on combustor efficiency, and airflow changing directions. Can't remember what it's called, but my channel page has a search bar.

Those are called swirler vanes. They cause the air going through them to swirl like a little tornado, which helps to increase turbulence and help mixing with the atomized fuel being sprayed from the fuel nozzle.

@@AgentJayZ the three T's of combustion, temperature, turbulence and time.

Air cooling. Not bypass type cooling. Often there is an oil cooler placed into the bypass stream of large turbofans.

Either configuration works just as well. The vehicle or installation can be designed for either. It's usually a preference thing of the designers.

In an industrial application, a hot end drive with a free power turbine is usually the easier design option, as it eliminates the complexity of taking a long power output shaft through the middle of the engine. That's the the way industrial gas turbines with aero-derived gas generators have to be designed, of course. Even those huge, heavyweight industrial gas turbines that are single shaft machines, usually have a hot end drive.

We would adjust the power consumed by the dyno by changing the angles of the variable stators, by changing the speed at which it is driven, and also by removing or adding stages of stators inside it. In this test, the vsv's are fully closed, it is running at design speed, and it has the last 3 stages of stators removed. A fully intact J79 compressor at full rpm normally requires about 30K Hp. We need it to need 5500 Hp here.

No hydraulic coupling. They are laminated steel flexible couplings.

You need to watch my power turbine videos.

The Tyne was originally designed to be a fuel efficient airliner turboprop. Your question does not make sense to me.

Whether it's a single shaft engine, or uses a free power turbine, all turboprops have a reduction gearbox. It's not helpful to think of gas turbine engines in piston engine ways.

@@AgentJayZ really are totally different things, thanks for the clarification

The gearbox manufacturer will make any ratio and direction specified. All you need to do is decide what you want.

It would almost certainly have required no more than an idler gear arrangement between the input and output gears of that gearbox.

Yes. The J79 compressor requires 30 thousand Hp at full rpm. We have removed three stages of stators at the back, and we have the VSV system set at minimum, which means the rotating blades have a very small angle of attack, and do very little at the higher rpms. If we opened up the VSVs, the blades would grab more air and require more power.

Do you adjust them for different engines to test? More powerful engines get more vsv?

G'day, The STOVL version of the F-35 has a Shaft-Driven Lift-Fan in a separate Bay forward of the Compressor..., between the Inlet Ducts... My guess is that the Engine itself is an Afterburning Fan-Jet with a Central Shaft from a Freee(wheeling) Power Turbine located behind the Low Pressure Turbine Array..., and the PTO-Shaft "must" perforce run right up the central Long-Axis of the Engine. The Freewheeling Power Turbine "must" therefore have the ability to feather it's Blades in order to prevent either overspeeding if left otherwise unloaded (during Forward Flight wirh the Fan shut down), or reducing the Exhaust Gasflow's propulsive velocity if the Freewheeling Power Turbine Wheel were to be stopped from rotating with the Blades pitched to recover energy from the passing Gasflow. So my guess is that they feather the Freewheeling Power Turbine in the Bum to shut down the Lift Fan at the Front...(?). And anybody who REALLY knows enough to be not guessing... (certainly not moi...!), is probably legally constrained from telling the likes of us anything much about it.... Secrecy Act, National Insuckuritity, and all that Marketing Jism..., OuuRaaah (!) kinda thing.... Such is Life, Have a good one... Stay safe. ;-p Ciao !

Sorry, but Mr WarblesOnALot has done just that. The engine in the F-35B is a version of the P&W F135. It doesn't have a separate power turbine driving the lift fan. The fan is clutched and de-clutched from the LP spool of the engine. There's no great secrecy about this: you can find stuff on Wikipedia, which will tell you that the lift fan was designed by Lockheed Martin and developed at Rolls-Royce, together with the swivelling nozzle arrangement. I find this curious, because I was able to look over the designers' shoulders as they were designing the fan, just down the road at R-R Bristol.

It is also to enlightening to read the patent. In order to extract more power from the turbine when the lift fan is engaged, the jet nozzle have some kind of flap which is crucial for the whole concept to work.

Torque meter on the gearbox input shaft. Rev counter on that shaft as well.

If you don't give me a time stamp, I have to watch the whole video and try to guess what you are referring to.

I do have a video called "Books!" which you might find useful.

@@AgentJayZ he meant the book from which you are showing/explaining us these diagrams.. ! 24:20

@@AgentJayZ 24:20 this one.. Probably

Nothing that small. One thousand Hp minimum. Go piston.

You can go with RC TURBO PROPS. .. A JETCAT SPT 10 9kw power.

I try to stick to what I work on.

@@AgentJayZ , Fair enough. It powered my ride for almost two decades in all that time I couldn't get a good explanation of the necessity and function of the recuperator. Or maybe I was too dense to understand. Anyway, I enjoy your channel, thank you.

None of this makes any sense. You seem unaware of the two types of drive systems: single shaft, and free power turbine. Both systems are used in various turboprops, and both systems are used in various turboshaft engines.

For a helicopter, you could use either a single spool engine (where the turbine drives both the compressor and the power output shaft) or an engine with a free power turbine which only drives the power output shaft. You can tell the difference between them by observing the rotor blades of the helicopter on engine start: If it uses a single spool engine, the blades will start spinning as soon as the engine starts turning, because the rotor and the compressor are mechanically linked. Whereas if the helicopter uses an engine with a free power turbine, the blades will only start spinning once the engine is producing enough power to spin the free power turbine - this will not be immediate, so there can be a delay between starting the engine and seeing the blades start spinning. The free power turbine approach is far more common for helicopters though because it's much easier to control the power output and hence the speed of the rotor blades. This is done by controlling the fuel flow to the engine: More fuel burned = more power generated = more torque produced by the free power turbine = rotor blades spin faster. The device which allows autorotation in a helicopter is called a spragg clutch. The position of this in the powertrain is important - the arrangement is power output shaft (from the engine), then reduction gearbox, then spragg clutch, then rotor blades. The spragg clutch is essentially a freewheel gear, similar in principle to what you find on the back wheel of a bicycle, but more heavily built since it deals with far greater power. This allows the rotor blades to spin faster than the output shaft of the gearbox, or for the rotor blades to spin even when the engine and gearbox are not spinning at all, but still allows the engine and gearbox assembly to drive the rotor. Imagine if the helicopter is in flight, with the engine at full power and the rotor blades spinning at or near their maximum RPM, and then the engine suffers mechanical failure or is hit by bullets from an enemy aircraft, either way it quits completely. In mechanical terms, this is analogous to riding down the road on a bicycle, pedalling as fast as you can, and then you just stop pedalling. The helicopter rotor is equivalent to the back wheel of your bicycle - it can keep rotating regardless of what the engine is doing. That's what helicopter autorotation is. Interestingly enough, the maximum altitude record for a helicopter (around 42,000 ft) is also the maximum altitude at which that same helicopter was forced to enter autorotation, because it went so high that the engines flamed out due to the intake air pressure being too low.

Short answer: no. Longer answer: aircraft design and aircraft engine design is undertaken by thousands of extremely capable people, and if this idea was worth the expense and complexity, it would be in service now. A quick survey of reality shows: ...

Proposals for variable cycle engines have been around for decades and nothing has ever come of them. There was a proposal to have such an engine for the proposed Boeing SST. The engine would have have operated as a turbofan for take-off and subsonic flight for improved propulsive efficiency and reduced noise levels. For supersonic flight, a valve arrangement between the LP and HP compressors would be actuated to divert the flow and reduce the BPR. We did actually tinker with the Boeing valve at R-R Bristol back in the 1980s, but it's so long ago that I can't remember exactly how it worked.

@@grahamj9101 seems like the only really good mixed cycle engine was that if the A-12 and sr71, between turbojet and ramjet. Anything more complicated (ignoring the inlet aerodynamics) doesn't seem to appear anywhere. Would you agree?

@@deSloleye I wouldn't regard the engine to which you refer (AgentJayZ doesn't like to discuss it) as a variable cycle machine, any more than I would the Olympus 593 in Concorde, which I worked on. Yes, in both cases, in supersonic flight, the turbomachinery was producing only a small proportion of the thrust. And yes, that other engine became what is known in the trade as a 'leaky turbojet', in supersonic flight. That was, I believe, because even compressor delivery air was too hot to provide reasonable cooling for the afterburner section, so compressor stage 4 (I think I recall reading somewhere) was tapped off and piped externally through the external tubes that are prominent on the engine. I've actually seen two of those unmentionable engines, here in England, under the wings of the aircraft that they powered.