# Is it currently possible to build a jet engine with 1,050 kN of thrust? (236,049 lbf)

Do we currently have the engineering know-how to build a 1,050 kN jet engine?

This question originated from the idea of changing a 4-engine aircraft into 2-engines. I chose the A380 since it seems to have the highest takeoff weight.

One A380 engine produces a max of 350 kN. If one engine goes out, the A380 still has 1050 kN available, and per regulations that should be enough even for takeoff. So if we switch to a two-engine aircraft, per regulation we need enough thrust for takeoff even if one engine dies, which means each engine would need 1,050 kN max.

I read this and this. They're in the same context of reducing a 4-engine plane to 2-engines, but do not answer the question if 1050 kN is achievable for a single engine.

• Possible duplicate of Why does the 747 have 4 engines instead of 2? – fooot Aug 4 '16 at 23:00
• The current record holder for most powerful jet engine is the GE 90-115b generating 127,000 lbf (594kn) of thrust. For some perspective, it has more thrust than the Titanic and the Mercury rocket that brought Alan Shepard into space combined. You are talking about a single engine twice that size... – Ron Beyer Aug 5 '16 at 1:49
• @RonBeyer You are talking about a single engine twice that size... meaning what exactly? Just because it doesnt exist doesnt mean its not currently possible. It means, first and foremost, that no one has ever ordered one. Could be because can't build it, or could be because they haven't yet gotten around to designing a giant 2-engine plane. – DrZ214 Aug 5 '16 at 4:58
• @DrZ214 If you are worried about to rudder authority to cope with 700 kN of asymmetric thrust, why do you think 1 050 kN would be no problem? – DeltaLima Aug 5 '16 at 7:09
• I think this is not a duplicate. The OP ask for the maximum possible thrust for an engine designed with today's technology. The threshold of 1,050kN is here to illustrate the possible application but may not be relevant. – Manu H Aug 5 '16 at 7:58

The limit to the size of turbomachinery is considerably larger than the size of current aero engines.

To estimate how large cores can get, we can look at power plant SCGT. You can get heavy frame turbines as large as 576 MWe for the SGT5 (this is half of a typical nuclear reactor at 1000 MWe). The aeroderivative LM6000 delivers 40 MWe out of a 270 kN turbofan core, and the largest aeroderivative, Industrial Trent 60, provides 60-70 MWe out of a 415 kN thrust turbofan core.

This would suggest an thrust equivalent of 3.5-4 MN or 800,000-900,000 lbf for the SGT5. You can't just fly a frame turbine like this, except in the hold: it's slow to spin up, its speed is on the low side, and it's not certified to aviation standards. But that's just a matter of design. It simply shows the amount of power that can be crammed into a single turbine core.

So, could we make a 1 MN engine? Yes, we are making cores with several times the power. Could we make an airworthy 1 MN engine? With effort, perhaps, of course it would cost money to develop. Would it be as good as the engines we have? That's the million dollar question. Or it would be, and more of a billion dollar one, if there were a market for it.

Is it currently possible to build an engine with 1050kN? No, because there's no design for it, because nobody has asked for it. Jet engine design is not a matter of scaling up existing designs, you can't just drag the corner and make it bigger. You have to model the forces involved to understand what your materials requirements might be, blades, etc. I would expect an engine that powerful would pose some serious engineering challenges which would need to be resolved.

Jet engines have been getting progressively bigger over time, so I have no doubt that if there was a need it could be done provided there's enough investment.

Of course it would require an airplane to be designed to use it - an engine that powerful is going to be very big, you'd need more ground clearance below the wing, or a different engine placement to situate those engines, plus stronger wing structures to handle the forces.

• related for the size problem. – Manu H Aug 5 '16 at 13:45
• Getting conflicting answers, so hopefully it will be decided by citations. – DrZ214 Aug 5 '16 at 23:08

As far as I'm aware there's no technical reason why not, but designing an engine with double the thrust of the current most powerful (GE90-115) would take a vast amount of money and time, especially as nothing on a similar scale has been done so it could not be a derivative design like many engines are, the unit cost would also be huge and it (assuming a high-bypass design) would be enormous so hard to fit onto a plane anywhere. All these combined give the real reason such a thing doesn't exist: given the compromises required, no-one wants one.

• To quantify "vast amount of money and time", development of new average size jet engine can cost on the order of 1 billion dollars. Development of something this size would likely be a 10 billion dollar project, if not more. – Daniel K Jan 6 '17 at 0:07

Technically yes. Economically no.

While the Meganewton engine is feasible, the number you could sell is so low that nobody will put money into its development. Unless some military feels it needs this engine no matter what, it will not be done.

• "the Meganewton engine is feasible": Details Peter? – mins Aug 5 '16 at 8:23
• Glue three GE90's together – Jon Story Aug 5 '16 at 13:02
• Use afterburners! – GdD Aug 5 '16 at 14:37
• Getting conflicting answers, so hopefully it will be decided by citations. – DrZ214 Aug 5 '16 at 23:08
• Meganewton sounds nice – Peter Nov 17 '16 at 12:54

Currently, no. The most powerful turbofan engines in production today produce in excess of 120,000lb, but to go from this to 236,000lb in one step would be too much of an engineering challenge and too big a commercial risk.