the Turbojet Start Sequence 

Yes, I think they have one at the Boeing museum in Seattle. Sitting under the SR-71 parked there... that you can climb into.

@@AgentJayZ Cool! They have a static display of the cart outside the AGE shop at Beale AFB.

Theres one at the AirZoo in Kalamazoo.

So the SR-71 is "technically" using the V8 engine to operate, yes?

In the exact same way that all groceries are based on diesel... yes.

Internal combustion, internal combustion.

Thanks again!

Thanks! 👍

You might like the predecessor to this video. It's called How to start a Jet Engine.

Every Friday, at our "safety meeting" I try to remind all the guys just how cool our jobs really are.

Thanks for the kind words.

Large Turbofan LP sections turn at 3500 or so. The HP sections at 8 to 10 thousand. Turbojets turn 7500 or so if they are big, and 12 or more if they are small. APUs will turn at 30,000-ish Starters maybe 38 to 45 The Allison 250 turns at 50 thousand. RC toy engines at 150 thousand Dentist drills are air turbine powered, and they go up to 250,000 rpm. The pattern here is that smaller things can spin faster without breaking up. It's more about the material strength than the bearings.

I was reading a book on the development of liquid fueled rocket engines. It described the stresses on components and fasteners similar to turbine engines... only ten times higher. I bet rocket mechanics get paid at least double the millions I make, eh?

Designed that way to fit in the Sabre. The vid is called "Orenda 14 in the Sabre", or something real close to that.

I've made a few vids about that. I think one is even called VIGV's in action.

​@@AgentJayZ yup, searching for that returns a few. After a bit of searching, One with a running engine is 'Afterburning J79 test in the snow' at mid 13' mark.

That would be you... living in an open grassland, next to a scrubby forest, next to a huge farm.

@@AgentJayZ yep

Not sure what a non manufactured anything is, but we can balance just about anything. Many places that deal with fans or rotating equipment can balance machinery.

That AI series was really good.

The Orenda has six struts in front of the IGVs. The struts are structural, and locate the front bearing housing, along with a gearbox and starter input, at the center of the front frame. The struts are hollow, with passages for radial drive shafts, electrical cables, and oil lines. They are streamlined in profile, but I'm sure they create some loss of airflow. Airliner engines have been engineered with overhung fans, so there are no struts in front of them.

As I have said many times before, the autogenerated english subtitles are so inaccurate and misleading, they only add confusion. I can only imagine the subs in any other language are at least as bad. No subtitles until they can actually help.

@@AgentJayZ okay👍

Nope. A startup is a cycle. Two short flights without a shutdown in between is one cycle.

@@AgentJayZ I disagree. I.e GE manual states that cycle is defined as a flight that consists of an acceleration to takeoff power, takeoff and landing. Regardless of if the engines are shutdown before the next takeoff.

A start and shutdown is also a cycle. Each engine manual uses different language, but industry standards are more generic. A hot start, if certain time limits are exceeded, is all of your cycles being used up all at once.

We've never used a cartridge start, because they are military, unnecessary, and dangerous. There's a vid of a cartridge start of an Avon in a Canberra bomber here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-Hz5-yM6fJ70.html It spins the engine quickly to min self sustain, or maybe a bit less, increasing the thermal stress, but lowering the already enormous mechanical stress placed on the engine. For the Avon, I don't know these numbers. The F-4 Phantom 2 had J79-15s in it, and they had a cartridge start option. Min self sustain on a J79 is about 2300 rpm, after starting at 1300 rpm. Idle is at 5000 rpm. Going from zero to around 2000 rpm in a second or two on a rotor that weighs about 1200 lbs is really hard on the starter drive through the main gearbox, so if any other method is starting is available...

@@AgentJayZ Yes, that must cause some stress. It's more like the start of a rocket engine and rocket engines generally are not started very many times although that is changing. The turbo pumps in a rocket engine look like small jet engines (I can lift one that generates 15 000 hp, the rotor is like a small dumbbell and each postage stamp-sized turbine blade generates as much power as a car engine). The gas generator used for the start has been described to me as similar to the one that inflates an airbag but bigger. 0 to 30 000 rpm or so in a few seconds.

A wing does not do that. There is no nacelle in this video. If you are talking about the starter fairing, it is shaped to fit the inlet duct in the aircraft. It's all explained in my video called the Orenda 14 in the Sabre. If you are talking about the bell mouth inlet fairing, it helps to reduce the inlet pressure loss due to the fact the engine is stationary. Inlet pressure is almost restored to ambient when using a bell mouth.

They are not chambers, but there are six of them. There are not six ignitors. Only two, on combustor cases 2 and 5. Only one is really needed, and the other is just for redundancy. The only way all six might not light is if there is something blocking flow to the fuel nozzle, or if the operators are not doing it right. I don't think I've done a video on interconnectors, also known as crossfire tubes. I think it might be time!

Exactly where you are thinking...

Not necessarily, you can get a buildup of fuel that burns in the tailpipe on startup. The EGT may not be affected much, but you have what is known as a tailpipe fire... a definite non-emergency. Or a rough, crude start, with lots of flames but no spike in EGT. The Orendas sometimes do that. Or a totally normal fiery start, like with the J47. A true hot start can happen without any flames coming out the back. It's the burning of fuel at too low an rpm, and the inability to accelerate up to idle. The engine just cooks itself to death due to insufficient cooling air, and that does not take a lot of fuel. That's why the operator of pilot looks at only two things: rpm and EGT until idle is achieved.

@@AgentJayZ thanks

The reason the velocity increases is because the volume increases, because an uncontained mass of air, when heated... ... ... expands. Eh?

Video called The Huffer

The most modern engine I've worked on is the LM500, which is based on the TF34, used most famously in the A-10.

@@AgentJayZ thanks a lot!

EGT is measured by thermocouples in the exhaust, usually just downstream of the turbine, but upstream of the accelerating jet nozzle.

The only noticeable lag is the EGT, and that is because exhaust gases are heating up metal parts. There is even more delay in the heating of the turbine blades, because they are much more substantial pieces of metal. We are measuring exhaust gas temperature, but what we are interested in knowing is the temperature of the metal parts in those gases,

EGT can be measured in any of those places. It is used as an indicator of the temperature of the tubine nozzles and blades.

Turbine engines don't have the sliding friction of pistons in bores, so the oil can get cold and not cause problems. I think the service limit for synthetic jet oil is -65C. It's up to the discretion of the pilot, but as long as you have a way to turn the engine to starting rpm, you don't need to keep the oil warm by running the engine.

@@AgentJayZ cheers, makes sense

No, typically there is a way to access the ignitors (spark plugs) while the engine is installed.

There is no typically. The Orenda in the Sabre: igniters inaccessible while intalled. J79 in the Starfighter and Phantom II, inaccessible. Only non-professionals call ignitors "spark plugs".

@@AgentJayZ well I am a non-professional. I've just always found Jets and engineering fascinating. I've never even been in a airplane before. Forgive us if we use the wrong jargon. A lot of us are average Joes I would assume and love your videos!

It's the minimum engine rotor speed from which the power supplied by the turbine can accelerate the rotation. The starter is no longer needed, and the engine can increase the speed of rotation up to idle speed on its own. Min self sustain is not idle, and if the engine stays at that speed for more than a few seconds, it will overheat and be damaged.

They get between 30 and 50 thousand volts

The igniters can run on almost any input voltage (at least modern ones, can't speak to older ones). The more voltage you give them the more frequently they produce the spark, they build up the voltage fed to them until they reach the amount specified for the spark.

@@ERIK31351 Many thanks for that info

We do not work on commercial aviation engines. That is a modular engine, and could be shipped without the fan module. If there was an industrial version, it would not be equipped with a fan, and we could definitely work on it. If someone sends us one, I'll record the work and test.

Depends on the engine but either between two of the turbines or in the exhaust nozzle after the exhaust turbines.

Some engines e.g. the RB199 in the Tornado had an infrared optical pyrometer which measured and displayed the temperature of the HP turbine blades as Turbine Blade Temperature on the cockpit gauge. It also displayed Exhaust Gas Temperature or EGT on the same gauge from thermocouples in the jetpipe downstream of the LP turbine. If I remember correctly, during start EGT was displayed but over 80% NH (high-speed shaft rpm) the gauge changed to TBT. Interestingly, the EGT was displayed as T7 on the gauge because they apparently were the same gauges used on Concorde for the RR Olympus engines.

Sounds the same to me!🤔

The quality of the recordings have gone up

Hope this is not a frustrating question what rpm is 100%

@@mikedupree832 From google: 7800

Each different engine has it's own max engine speed. The % system was created to make it easier to avoid difficulties, because different engine type run at different speeds. The Orenda 14 is at 100% at 7800 rpm. The J79 at 7685. The LM2500 at 9200. The AI25 at 14,000 The RR250 at 50,900. The PT6 at 42,000.

@@AgentJayZ thanks for the information. I was thinking that the idle speeds would be close and the max speed different. Almost like automobile engines. Thanks for your

I think that would be cool, and really useful in one possible future... but I am already involved in too many activities that I don't do enough of.

I'm thinking of getting one and would probably be getting a handheld device soon so I can learn something. What's your call sign though?

Glaaaarghhh. Word salad. Good luck figuring out what that even is, never mind building it.

Again! Nothin gets by you...

@AgentJayZ lol yeah I'm a big fan of you and your channel

If your ideas or designs have any value, the best people to decide that are the engine manufacturers.

I run Jet City Turbines, where we carry out the overhaul of vintage turbojet engines for early fighter jets owned by private collector pilots. I've heard from dozens of people claiming to have great new designs. I have made a few videos about that subject. Here are two: "So You Want to Design a Jet Engine" and Design and Build a Jet Engine Yourself?" On my channel page there is a search bar, and you may find these vids interesting.

Hey, your idea sounds great. I know a bloke in Nigeria who is seeking help in moving large amounts of cash...maybe you could help each other...maybe meet up over some google translate training.