Hey lei, Can you Check out the SABRE engine , this is one of the most promising engines for commercial flight using “rocket” engines. Using my limited knowledge, it basically Removes the constraints of having 2 engine for earth and vacuum . It used a jet engine for the atmosphere therefore using “normal air” to fuel it instead of liquid oxygen and then once it starts to leave the atmosphere , it closes up the gap which sucked in the air and uses onboard liquid oxygen all whilst being in the shape of a plane . Please check it out !
I was thinking the same just use a sabre based only atmosphere variant don't carry lox just fuel and go hypersonic or something like scramjet engines wich enable hypersonic flight
What about the skylon plane with the sabre engine which is an air breathing rocket engine designed to do exactly what this video was about. Airbus has even invested heavily in it for there future planes
I've been following them for a while too, but I think there would be more to make a video about once they complete their static fire test they are preparing for.
7:12 I'd like to point out that there's hybrid approaches out there. There's hybrids between regular jet engines and ramjet engines and there's hybrids between ramjet engines and rocket engines. So since there *are* hybrid approaches you *can* get some of the effects of both worlds. But yeah, the more towards the rocket side of things you go the less efficiency you get.
You forgot to discuss hypersonic travel in the upper atmosphere, using hybrid engines (SABRE). If you played Kerbal Space Program, you would have known about it. Also, the term 'aircraft' is both used in the singular AND plural form, you don't need to add an "s" to express it in plural.
Hey Lei, have you heard about the Reaction Engines A2?It takes the Skylon design, makes it way bigger, and strips out the rockets and oxidiser tanks. It can't go to space, but the engine precoolers allow it to fly way faster than conventional jets could.
Can we make a system where we send stuff (products) Similar to gas/fluids? (Getting lets say pizza or gums from miles away. But packaged in a very fast highway-like pipe?) Orrr. Can we send stuff from country A to country B with BFR? (Without getting destroyed) Getting a high res tv directly from a country that makes it cheap. Transporting foods and supply to stranded people asap Sending troops across the globe in just 30 min. And give reinforcements directly from the homeland. (Since it could have a rough landing. This'll be only used at clear/safe skies/bases)
Hey Lei, big fan of your videos here :) So how about a BFS with no first stage. just a single sea raptor rocket engine, bigger wings and 2 jet engines under the wings but fixed to the belly for aerodynamics similar to fighter jets, then it would be performing the following: 1 - Horizontal takeoff from an airport runway and get to an altitude of about 12 000 m and Mach 0.85 just using the jet engines (efficiency) 2 - As soon as it is over the ocean or non populated area, it will turn off the jet engines and fire the rocket engine to get to Mach 6 or more, mostly to avoid generating the sonic boom over a populated area (speed and safety) 3 - After reaching a near space altitude (100 km), it will glide towards it's destination in a similar way the space shuttle did 4 - The jet engines take over as soon as the density of the air is at operating level, let's say 10 000 m to have enough oxygen for the ignition of the kerosene 5 - Land horizontally on an airport runway What do you think? is this not a viable solution as something in between an airplane and a rocket? Thanks in advance for sharing your thoughts ;)
The theoritical SABRE engine is also worth looking at as it is a hybrid jet/rocket engine, capable of switching between closed and airbreathing modes and uses hydrogen and oxygen which results in a high isp in space.
You were really focused on Concorde using afterburner to fly at high speeds, but the huge advantage that Concorde designers had was the way airflow was managed allowed Concorde to maintain supersonic velocities without afterburner. This made the transit portion of the flight far more efficient than other vehicles that need afterburner at that speed. The huge problem with Concorde was noise, this limited where it could fly, and for a long time was used as a reason to not allow flights to New York.
I think supersonic flight is kind of an unhappy medium between subsonic flight and space flight. A long haul airline can travel very far at subsonic speeds with reasonable seat mile fuel consumption. Super sonic flight takes much more fuel, a much more expensive aircraft, and still takes hours. The advantage that rocket planes have is that they can burn all the fuel at the start of the flight (even if the rocket engine is far less efficient than its air breathing counterpart), leave the atmosphere and fly to anywhere on just inertia. The BFR is definitely not optimized for point to point travel, but does seem feasible enough to possibly enter service in some capacity and open the door for other more optimized suborbital transport systems.
boboprime - really slow or really close to the sound barrier, sure. But supersonic flight always means a higher cost per passenger mile relative to modern-day cruise speed and altitude.
@@AmbientMorality "But supersonic flight always means a higher cost per passenger mile relative to modern-day cruise speed and altitude." That is actually not true. If you fly really high and rather quite fast, the fuel cost might be decreased.... or rather it will. The question is really about configure the engine to work.... and well.. someone have already done that
The big difference is that a conventional rocket engine carries not only its fuel, but also its oxidizer (usually liquid oxygen.) That is a huge weight penalty for anything flying in the air, where we can just pull in air and use the oxygen in the air as the oxidizer. I know a company has theoretically been working on a "hybird air breathing rocket" that would use the oxygen in the air at low altitudes, and carried Oxygen at higher altitudes/space. Upon some searching, it looks like it's still being developed: SABRE, being created for the Skylon Spaceplane concept. In theory, it could fly like Concorde in the atmosphere, then as it gets too high to reasonably use air for oxidizer, switch to carried oxygen and act as a rocket to reach orbital speeds/altitude.
Yes, but it doesn't necessarily matters. If the fuel is lot cheaper and people willing to pay more for not having to sit in a plane for 10-15 hours, than it can work out. The BFR will use methane, which should be a lot cheaper. And I'm pretty sure most people really hate long flights, so they will be willing to pay more.
It will thats why fighter jets doesn't fly on afterburner too long, but there is ramjet and it's more efficent - blackbird flight on that all the time :).
Extremly fuel-inefficient - if you remember that the industry is whining about 4-engine aircrafts like the 747 or a380 its just not feasable to use a much more inefficient rocket engine
I am interested in the use of retrofitted rocket engines on conventional aeroplanes to enable one-time-only VTOL or STOVL operations. The best example is the failed attempt at doing this on the C-130 for Operation Eagle Claw in Tehran in 1980. The videos are easy to find. My question is: With 40 years of progress in both rocket engines and computer flight control systems - and with the disappointing limitations of the V-22 Osprey - is anyone revisiting this idea?
Rocket Engines are basically designed to get high thrust to achieve high speed that is the major purpose, but if we use rocket engines for commercial aircraft then : - It would increase speed but less comfort simply because rockets stays at each section of atmosphere for short time interval but aircraft travels within a range of atmosphere so control and stability would be a challenge at those Mach Nos.
The gap in efficiency between rocket engines and jet engines is immense, even with afterburners engaged. The Concorde in afterburner flight at top speed managed around 3,000 seconds of specific impulse, while subsonic turbofans manage well over twice that number. The most efficient kerosene rocket engine ever produced (RD-0124) can only hit about 360 seconds in vacuum, where the most efficient at sea level (RD-181) is 312 seconds.
Very true. I don't think a rocket engine will ever be used for anything other than experimental atmospheric flight. The advantage of rockets is that they don't have to fight atmospheric drag or provide lift for hours on end.
afterburner is actually incredible fuel inefficient. And since air travel is a pretty price elastic market, I don't thinking it could work unless the payload it can carry is significant larger than turbofan based airplane. On the other hand, typically thrust to weight ratio is much higher for rocket when compare to turbofan, so I guess if the cargo weight is high enough, it might be worth it as a cargo transport method. But it needs to be pretty damn high though.
Wouldn't a proper compromise be something like spaceship two or something Bigger mounted on something like a Stratolaunch have it do a suborbital flight half way across the world, land, refuel and bolt it to a new stratolaunch and do that over and over?
Rockets carry their oxygen with them because they are flying in space where there is no oxygen. In the Earth's atmosphere it is smarter to use oxygen in the atmosphere. Theoretically it is possible to build a jet engine that is as powerful as a rocket engine.
It's also possible to build an airbreathing rocket engine that can use atmospheric oxygen. But that's really what the afterburner does. It basically turns the jet turbine into a rocket. More or less.
@@ALTruckerDad I have been thinking about this kind of engine which is basically like afterburning turbofan but it can switch from atmospheric oxygen to LOX. Working kinda like the sr71 engine but the afterburner also has LOX input so it could work in space.
Juho Mehtätalo Why would you use a turbofan? They're only useful up to ~mach 2. If your goal is to make a hybrid engine, then you want the atmospheric half of the engine to be practical across a wide range of speeds and altitudes. Some form of ramjet would be much more suitable, not to mention already the combustion chamber on a ramjet is already pretty close to a rocket and they don't have to drive a turbine.
@@lazarus2691 Do you know how the sr71 blackbird engines work? They start to use the afterburner like a ramjet when they get enough speed. It works by bypassing air straight to the afterburner. The engine could work like that. Then when it runs out of atmospheric oxygen it could start using LOX from fuel tanks.
What about the Sabre engine of the Skylon project? They talk about a possible spin off for the commercial flight industry. Essentially an airbreathing rocket engine, high speed (mach 2+) and no need to carry all that pesky oxygen around. Exactly what you were looking for this episode ;)
Skylon! They try to make air breathing rocket engines, has been developing this for over 30 years and says they’re done within five years. Static fire of individual parts are made, I think next step is static fire of the complete engine. There is no reason to bring oxygen if it’s all around you. :)
There could be one application of rocket engines: high altitude flights. There is no oxygen and no drag, so it would make sense for long distant flight with very high speeds. Or at least might.
A factual error, you need to distinguish fuels from propellants. Kerosene is a fuel, ammonia is a fuel. LOX is an oxidizer. Both fuel and oxidizer make up the the vehicle's propellants.
One more thing that may have been worthy of appearing in your video is the SABRE, which promises to reach up to Mach 5.0 while airbreathing. Still in development though.
Hey Lei, big fan of your videos here :) So how about a BFS with no first stage. just a single sea raptor rocket engine, bigger wings and 2 jet engines under the wings but fixed to the belly for aerodynamics similar to fighter jets, then it would be performing the following: 1 - Horizontal takeoff from an airport runway and get to an altitude of about 12 000 m and Mach 0.85 just using the jet engines (efficiency) 2 - As soon as it is over the ocean or non populated area, it will turn off the jet engines and fire the rocket engine to get to Mach 6 or more, mostly to avoid generating the sonic boom over a populated area (speed and safety) 3 - After reaching a near space altitude (100 km), it will glide towards it's destination in a similar way the space shuttle did 4 - The jet engines take over as soon as the density of the air is at operating level, let's say 10 000 m to have enough oxygen for the ignition of the kerosene 5 - Land horizontally on an airport runway What do you think? is this not a viable solution as something in between an airplane and a rocket? Thanks in advance for sharing your thoughts ;)
emir h.a The BFS is not designed to land horizontally, you’re better off developing a brand new platform rather than cannibalising a vertical launch system.
I agree with you. but we are already supposing it has bigger wings and 2 jet engines, so it wouldn't be too hard adding some wheels to this new design ;) Frankly speaking, the BFS in my example is not meant to be a replica of the actual BFS, it's more of a basic idea of little modifications that could get us supersonic passenger planes borrowing the efficiency of jet engines for the first phase of getting off the ground at subsonic speeds, then getting the speed of a rocket once it is in the right conditions. I see no reason why the BFS wouldn't be able to perform a horizontal landing, I believe its carbon fiber fuselage is more than capable of supporting its weight on landing gears. The only reason the BFS was designed to do a vertical landing is for landing on the moon and mars where you have no or little air density to give lift to the wings. But since this video is about intercontinental travel on earth, a horizontal takeoff and landing make more sense and is way safer and smoother from a G forces point of view. What do you think?
emir h.a I think it’s pointless. It isn’t aerodynamically designed to operate like an aircraft. If something is going to operate like an aircraft, the base design should be an aircraft.
You need like 20,000km/h for a suborbital hop. Jet engines can give you like 2500. And it's even worse for altitude. Jet engines don't work well above 20km, and you have to go over 100km. And if you only go supersonic over oceans you lose a huge amount of time. That was one of the reasons why the Concorde failed. What you want is the Sabre engine. That's an air-breathing rocket engine.
Henry Stitt I disagree with you because of the following: An aircraft and a rocket are both cylinders meant to resist the negative air pressure at high altitudes, in the current case the BFS is built to withstand higher pressure differences as it is built to fly in the void of deep space while offering its passengers the same level of air pressure as what they would get on earth. So the BFS has a more solid cylinder, making it an excellent airplane frame which would better resist the effects of repeated compression and decompression. The aerodynamics of the BFS are already designed for hypersonic speeds, so only the wings need to be redesigned for providing more lift on subsonic speeds and much slower speeds for taking off and landing.
Ramjets and Scramjets are the solution to faster jet engines. With the use of a Scramjet we can theoretically get speeds up to Mach 10. The famous SR 71 Blackbird used a ramjet engine for its high speed.
What about the P&W J58 or a comparable turboramjet? To me it seems like the way to go if you want to achieve efficient supersonic or even hypersonic travelling.
Not really. The first problem is that it requires a completely unique logistics network and that's insanely expensive. Even the US military found it too expensive. The second problem is extreme temperatures. Which mostly causes the first problem. Plus SR-71 pilots had to wear special air conditioned suits to stay alive. The third problem is aerodynamic forces. At hypersonic speeds if your plane isn't aligned perfectly it breaks into million little pieces instantly. If you want to fly fast it's best to avoid the atmosphere.
András Bíró Agree on that, but even the best afterburning turbofans reach their limits at about Mach 3 (MiG 25, R-15B-300), problem being that the rotors start melting. Only options at this speeds ar RAM- or SCRAMjet engines. Those obviously have the problem of not producing thrist at subsonic speeds. When thinking about having a RAMjet and a afterburning turbofan you get the problem of it getting too heavy. rocket assisted ramjets and scramjets, which use decoupling disposable rockets will soon work, but are extremely expensive. The only option left would be a turboramjet comparable to the J58. Of course, nowaday that thing would not be viable, but I‘m pretty sure it would be possible to develop an engine that is better in any way possible.
András Bíró About the cooling problem, I don’t know too much about how to solve that but I‘m sure there is a way. And about the aerodynamic forces, even at hypersonic speeds it’s possible to build selfstabilizing aircrafts. They would probabely be really unstable at low speeds, but that can be handled.
Those problems could be solved potentially, but it's unnecessary, there are better solutions. 1. For short range (~1000 miles or less) the Hyperloop or something similar is the best, or even regular high-speed train. 2. For medium range supersonic electric VTOL planes. The huge advantage is that they can go way much higher and much faster than jets, because they don't use that delicate combustion process. Flying in less dense air also means they have to use less energy. This isn't just saving money, but makes the whole thing possible, because batteries have much less energy density then jetfuel. In less then 10 years this will be possible. 3. For long range rockets can be the best. They won't necessarily be cheap, but nothing beats their speed. Pure rockets may be wasteful, but they are simple and available now, and if they are reusable and their fuel is cheap, it doesn't matter much if they are wasteful. Later we could use something like the Sabre engine. And if you want fast but dirt cheap long distance travel, orbital rings are the solution. As a bonus they can take you anywhere in the solar system for little additional cost.
András Bíró I agree on the hyperloop, but I don‘t see supersonic electric planes in the closer future. Batteries just don’t get the energy density necessary. And with rocket I still think the pure fuel mass burned is too high.
There is something much better than afterburner - ramjet. It's more efficent in high speeds, blackbird used that and the "next concord" will also use this technology.
The key is a phrase you didn't even use: Air breathing engine. An engine like the Blackbird uses would be a way to power near hypersonic flight and challenge bfr.
there is also scramjets and ramjets. Biggest problem with supersonic flight is no country will allow it over land until something can be done to soften the sonic boom(NASA is actually studying this). If we could find a way to make supersonic or even hypersonic flight over land viable in both boomyness and fuel/seat ratios you could have even short flights from NYC to Asia. As for E2E BFR... I think it is 100% possible and workable from an engineering perspective. Business wise it would need a good case for cost, But equal to a first class international flight ticket would probably be viable. Even more so if business class prices. However engineering and business are child's play compared to the ultimate barrier for inter-city BFR and that is policy surrounding launch and landing pads. SpaceX would have to deal with multiple nations and cities on this and red tape and NIMBY are forces that cannot be fixed merely with lots of very intelligent people. Rocket Science being a Science functions on logical outcomes, Dealing with governments is like trying to herd cats through the testing department of a laser pointer factory.
In case of physic, answer is yes. In case of economic, answer is no. That's the same thing as why we don't put F1 engine on the public bus. It's technically can be done but not economic viable.
So, not even an aircraft that stays just sub orbital and hits rediculous speeds by accelerating in an area where there is very little atmosphere using rocket engines is a remote feasibility?
There is a SABRE aircraft concept with no oxygen but with 4 engines, in the 300-400 seat range with a top speed of 5500km/h. It would use only Hydrogen. And its possible that hydrogen is getting cheaper than fuel in the future
Really cant have made much research on this topic. There is two HUGE parts missing. 1: Air density. 2: Air breathing rocket engines. 1: The higher you go, the less dense the air are. This limits the effectiveness of a engine. A commercial engine is REALLY efficient at 12 000meter. But it don´t even work at 20 000 meters. A engine made for 20 000 meter will always be less efficent, but the air is less dense, making the aircraft more efficient in total. For sub sonic aircrafts this effect is very smal. Making 12 000meters pretty much a optimal altitude for sub 1000km/h aircrafts. But for 2000km/h altitude aircraft 20 000m of altitude is much more efficient.... and well that is exactly what Concorde did. For 3000km/h, higher altitudes are needed, about ... well 30 000 meters. And well, here is the SR71. Well 26 000 meters and 3500km/h.... officially. (worth noting, SR71 is much larger than most people think... longer than a Boeing 737-100) If you go higher, you become more fuel efficient. But there is a problem. 30 000meter is pretty much the limit of what a Jet engine can work. YES a afterburner can work at higher altitudes, but if you don´t have a Jet to keep it lit.... well... it don´t matter... it wont work. Now, there is a way around this. And ..now this is what makes it real interesting. It makes the aircraft faster AND more fuel efficient.... well of sorts. Scramjet. en.wikipedia.org/wiki/Scramjet Its pretty much a afterburner only engine. And it turns out, if you fly sufficiently high, and sufficient fast, the low fuel efficiency of the afterburner is totally offset by the low drag of the very high altitude. This is sort of a oddity, because the faster you go, the more fuel efficient it gets. The scramjet does have one significant drawback. Sort of a deal breaker. It don´t work under 2,5 mach. It have to have a secondary engine... and well, while the scramjet is very light... the secondary engine.. will not be. That gets us to point 2. Airbreathing rocket engine... While this was considered a theoretical engine just a few years back. The first actually working version was tested a few years back... and.... i say wow, does that engine have a sexy start up sound. ua-cam.com/video/wxdXLl9P62M/v-deo.html While this engine is not as efficient as a normal turbofan engine att normal speeds or altitude, its really not as inefficient at most other. It even give the concorde run for its money at its home turf. This engine got twice the weight to thrust as a commercial turbofan. This make it incredible strong. While its not very efficient at lower than 20 000 meter altitude. It will only take about 5 minutes to reach that altitude. At about 30 000 meters it can reach mach 5, and do that VERY efficiently. But the saber have one more trick up it sleave. It can also run on close cycle with oxygen. This is really smart. Because it can still get to 30 000 meters and 5 mach on air. Then swich to oxygen and have a very efficient rocket engine. When it does that it increases the thrust by 50%, as well as being (for a rocket engine) very efficient, with a ISP of 460, that is almost 50% more efficient than the SpaceX rockets. The rocket engine can be used to boast the aircraft up to 70-80km where the air is so thin that there is virtually no air resistance, then it can glide back to earth using no fuel what so ever running at 10-15 000km/h. The great thing about this is that the oxygen is the heavy part of the rocket. Using oxygen for just a minute or two to accelerate. This make it possible to both go London to New York in a hour. Or ho London to Sidney in two hours in "space mode" (With a bit less cargo capacity). The nice part about this is that going space mode is even more efficient then going
Imagine minding your own business and then a FUCKIN ROCKET POWERED 747 SPEEDING ABOVE YOUR HOUSE AT MACH 4 BREAKS YOUR WINDOW AND EARDRUMS. Yeah there's a reason why airlines cant even go supersonic.... Just too loud
Really, the Okha rocket plane was envisioned as a one-way Kamakazi platform. It's limited range doomed it. But in Germany, the Messerschmitt 163 Komet was a success, as least technically. It should have been in your timeline.
Exactly. It may have been built after the He 176, but it still used solid rocket motors, and was technologically much more primitive. There's no reason to include the Okha on a timeline of rocket planes. The Bell X-1 would have been a better step between the He 176 and the X-15, though as you noted the Komet would also make a good example.
Before i watch, i would say no because rockets are too inefficient to be used in an atmospheric environment for a long period of time. The engines are also sometimes quiet heavy and bringing all that fuel will bring down the useable payload size of an airliner.
Doesn't help much. The flight ceiling of a turbofan engine isn't very high relative to orbital altitude, and it isn't traveling very fast relative to orbital velocity.
The speed you quote seem to be in atmosphere. Rockets work best in space (they even carry oxygen) and aircrafts work best in the atmosphere. Compare a both strengths before coming to a conclusion..
Short answer: no. Long answer: nnnnnnnooooooo. Simple answer: nah. Simple answer in German: nein. Complex answer: 1- turbo prop are the most energy efficient, then jet, then rockets. Why? Because props and jets use the atmosphere as reaction mass, the stuff that gets thrown backward to create a force by Newtons laws of motion. Rockets fight the atmosphere with its own fuel as reaction mass. 2- economics. The Concord proved that passengers will opt for cheap, slow and comfort. Concord was fast and sexy but it was hecka expensive and cramped uncomfortable. For the price of a cramped Concord seat you could get a first class seat with champaign, gourmet food and loads of legroom on a jet liner. 3- safety. Rockets have about 5% failure rate. In manned flights rockets have killed 1 in 31 space travellers. If airliners had a similar death rate they'd be killing tens of THOUSANDS every single day. Rockets are for getting to and moving around in space. Aircraft can't. We should use rockets where they are the only option. We should use jet and props where they reign supreme... in the atmosphere.
This is all completely wrong. 1. The Falcon 9 first stage reaches 8000km/h. That's already far faster than any airplane ever. But the second stage can go over 30,000km/h. That's like 20x faster then the Concorde. 2. Supersonic passenger planes don't exist, and likely won't exist any time soon. The problem is cost and more importantly noise pollution. Rockets make even more noise, but it's very contained. 3. Rocket engines can be more reliable then jet engines. They are a lot simpler and work for a few minutes instead of many hours. Historically they weren't safe only because they were one use only and saving mass was essential. That's not the case with the Falcon 9 or the BFR. Their engines are designed to be used many times, especially the BFR engines, which already implies much higher reliability. But reusability brings down costs so much that engineers can "waste" precious mass on safety margins. The Falcon 9 had over 50 launches, and each one uses 10 Merlin engines. That means around 500 engines were used so far, many of them flew twice and landed twice. Of all of these only one engine failed, and that was on one of the earliest missions. And even then the rocket reached it's intended orbit and released it's primary payload on the desired orbit. The BFR is designed with even more redundancy. The booster and the ship too will be able to safely land with multiple engine failures. 4. Rockets are actually less vulnerable to bad weather than planes. That's because they don't rely on big wings and external air supply. Landing a plane is a very delicate procedure, many things can go wrong that result in a disaster. A sudden change of the wind is enough to crash a plane. Rockets don't have wings, and their round shape is the best to resist wind. The BFR has aerodynamic surfaces, but much relatively a lot smaller than plane wings, and it's powerful engines and reaction control system can counter the forces and it's computers can react to wind changes thousands of times faster than human pilots. Plus their order of magnitude shorter trips allows them to know the weather at their destination with a drastically higher accuracy. Also planes need to land at high speeds and use tire traction to stop safely. If the tarmac is slippery, they might not be able to stop. That happens often. Rockets brake with their redundant engines in the air, and touch the ground gently. You can land a rocket on any small, reasonably flat and stable surface. You can land them on ice, deep snow, sand, mud or anything as long as they don't tip over. By the way, icing is another big issue in aviation. Too much ice on the wings and they don't generate lift. Or your essential external sensors can freeze over. Rockets don't need to generate lift, and don't have external instruments. In fact, since many rockets use cryogenic fuel, which pretty much guarantees a lot of icing, and that doesn't seem to cause problems. 5. Rockets are less vulnerable to collisions too. Birds strikes can kill a big jet engine, but rockets engines don't have to suck in air, so they are immune. When the rocket flies forward it's aerodynamic shape can easily deflect birds, and during landing, when they are low enough to encounter birds, their engines are firing, so they simply blow away birds. And even if a bird hits an engine bell, it's far less delicate then the internals of a jet engine. In a jet engine the turbine blades are rotating at extreme speeds, so any small imbalance makes them explode. Rocket engines don't have such exposed moving parts. Rocket engines are also immune to dust, water and hail, again, because they don't have to suck in air. Since rockets fly precisely on predetermined trajectories, they won't collide with each other, and since they fly through the path of other aircraft vertically in very specific small areas, it's again very easy to avoid collision. 6. Rockets land in a few seconds, and don't need much space for that, so there won't be congestion around spaceports. They can even land close to each other at the same time, as we saw it with the Falcon Heavy side boosters. The traffic on and around large airports is insane, and that's often causes disasters. Not having to deal with that is a huge benefit. 7. This all also means that delays will be far less frequent.
3. "A lot simpler"? Turbopumps are in harsher steady-state conditions than aircraft compressors and during thrust transients the conditions are ridiculous. These severely limit life, particularly compared to much gentler startups of turbofans. Now consider that the fatigue on engines like CFM56 is primarily due to transients from idle to takeoff thrust and back - not the flight hours at cruise. When a rocket engine has to do multiple, harsher startups over a single flight, it will require more maintenance and care. 500 engines running for a combined 60 or so missions is about 35 total flight hours across the Merlin family. 4. Unproven. And what do you even mean "this happens often"? Planes do not fail to stop on the runway "often". De-icing is not difficult; it's another logistics challenge and rockets will have their own set of logistics challenges. Also, landing in mud or deep snow or whatever fifty scenarios you have would be undesirable from a logistics standpoint. Still need to get things (passengers, propellent, etc) to the rocket. 5. Probably true but bird strikes don't happen often enough for it to significantly affect engine lifetime. 6. They need spacing for safety, just like airplanes. Also, they need to be reasonably far from passenger terminals for the same reason that runways typically are separated a decent ways from the terminal. Also, where are these disasters that happen so often? There's a rare incident, its not nearly as frequent or dangerous as you seem to like to make it sound.
3. Yes lot simpler. The operating conditions are a completely different matter. Turbo pumps may experience worse conditions, but for much shorter times, and it's way much easier to design them to withstand those conditions than to make a much more complex machine reliable. Flight hours don't matter, the number of missions do. 4. If you are familiar with plane crashes it's very easy to see why it's true, and I explained it too. 5. Killing the engine instantly is in my book is a significant effect. While engines can survive ingesting small birds, lager ones or multiple hits are much more dangerous. en.wikipedia.org/wiki/Bird_strike#History_of_incidents 6. Large planes have to be separated by minutes due to wake turbulence. Rockets don't have this problem. As I said we already saw simultaneous landings closer to each other than the length of a short runway. Planes need a lot of space to land, rockets don't. The Falcon 9 can already land within a few meters of the center of the landing zone. The BFR will land with centimeter precision. The problems are noise and safety. Both can be solved in several ways. For example by surrounding each landing pad with very thick sloped reinforced concrete walls.
3. I grant that flight hours are not all that important (I said that in the first part of my answer). As you said, flight hours are less important than engine cycles; transient conditions on a turbopump are way worse than any airplane engine so this severely limits lifetime. I don't know how it's "way much easier" to design turbo pumps to withstand these conditions; you have an order of magnitude higher thermal loading, much higher angular velocity (due to much smaller turbine), and, if anything, even more restrictive mass conditions. 4. Runway overruns are ridiculously uncommon. De-icing crashes are very uncommon, especially with the number of techniques developed to make sure that can't happen. I am familiar with plane crashes, and the core fact is that they don't happen very often at all. 5. Sure. But almost no engines ever ingest a bird. Overall, the fact that some very small percentage of engines have their lives cut short does not significantly affect the total engine lifetime. 6. Build a runway parallel to the existing runway. Capacity issue resolved. Yes, this takes space, but we already have accounted for this space in airport design. I'm not sure how very thick sloped concrete walls are supposed to make a rocket engine or a sonic boom any quieter, unless your very thick sloped concrete walls are also a few kilometers high.
3. It's a lot easier to make something stronger than to figure out and prevent all the ways a complex machine can break. It doesn't matter how bad are the conditions, we know exactly what they are, and we can easily test whether the turbopump can withstand them. It's way harder to map and test all the intricate ways that thousands of components can interact with each other. And turbopumps are in an fully controlled artificial environment, while jet engines are exposed to the outside world and it's infinite amount of different conditions. 4. Plane crashes are ridiculously uncommon in general. I mean when a plane crash happens, the leading causes are pilot error, weather and mechanical errors. Rockets are flown by computers, and don't experience the complex situations that require human pilots in planes. Rockets don't care too much about weather either. That's where runway conditions, icing, wind and other stuff comes into play. And rocket engines are a lot simpler, work far less between inspections, and can be more redundant too. 5. Again, plane crashes are extremely rare in general. And to keep birds strikes from being a major issue requires a lot of hard work. Airports use a ton of different methods to keep birds away, and jet engines are designed to survive most bird strikes. Still, accidents happen. I'm not saying that this is the worst problem in history, but it's a problem and rockets are immune to it. 6. Space is exactly the issue. Not just on the ground, but mostly in the air. Since flights can't be scheduled perfectly, planes have to be juggled by air traffic controllers in real time, and it's the worst around major airports. This is one of the biggest problems of aviation right now, and limiting the amount of traffic airlines and cities can handle. Expanding airports, even when possible is extremely expensive, and takes several years. Rockets fly in and out of spaceports vertically, so they can be far more densely packed, and don't interfere with each other. And the short and very predictable flights allow them to reserve a landing spot before takeoff. And it's necessary too, a rocket can't really wait for it's turn once it's launched. The wall's don't have to be too high, if the passengers aren't out in the open. The concrete walls are needed more against flames, hot gases, and possible explosions. Against noise simple sound proofing can help too. There are several possible ways to do it. The simplest is something like the bridges big airports have. Just much more robust of course. Or another way is to synchronize landings and launches and move people in and out in between them. It could be a complex logistical problem, but probably can be done. Or you can even use underground launch pads. ICMBs are routinely launched from underground silos, and the Falcon 9 already lands precisely enough to fit in a tight hole. Then you can just close the lid on them and the passengers are perfectly safe. Two rockets flying close to each other still could be an issue, but it's avoidable since they spend just seconds near the spaceport. And again, good sound proofing can drastically reduce the problem.
Please use metric, only the U.S and two other minor countries use imperial.
Notice he's talking about US-based projects on a US-based platform (UA-cam)... we can talk metric when metric is worth talking about.
dude really, that's just ignorant. The science world uses metric because it's a better system.
I was kidding, but thanks for the great answer!
yeah sorry man, will edited again
@@Cadunir The engineering and aviation worlds use imperial more often than metric. You are in no position to be calling people ignorant.
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Thanks Sara!
Hey lei, Can you Check out the SABRE engine , this is one of the most promising engines for commercial flight using “rocket” engines. Using my limited knowledge, it basically Removes the constraints of having 2 engine for earth and vacuum . It used a jet engine for the atmosphere therefore using “normal air” to fuel it instead of liquid oxygen and then once it starts to leave the atmosphere , it closes up the gap which sucked in the air and uses onboard liquid oxygen all whilst being in the shape of a plane . Please check it out !
Touche! I think Lei missed the SABRE engine.
the sabre engine uses stores oxygen fore use once it's out of the atmosphere but as lei said, thats not a constraint with airliners
I was thinking the same just use a sabre based only atmosphere variant don't carry lox just fuel and go hypersonic or something like scramjet engines wich enable hypersonic flight
What about the skylon plane with the sabre engine which is an air breathing rocket engine designed to do exactly what this video was about. Airbus has even invested heavily in it for there future planes
Richard Williamson Same question...
yep same here...
Nice vid Lei! How about a video on aerospike engines. There is company called ARCA aerospike that is trying to make it commercial.
I've been following them for a while too, but I think there would be more to make a video about once they complete their static fire test they are preparing for.
7:12
I'd like to point out that there's hybrid approaches out there.
There's hybrids between regular jet engines and ramjet engines and there's hybrids between ramjet engines and rocket engines.
So since there *are* hybrid approaches you *can* get some of the effects of both worlds.
But yeah, the more towards the rocket side of things you go the less efficiency you get.
if you start traveling suborbital then it becomes more efficient since there's no drag
I always like your videos bro. Especially on ISRO.
You forgot to discuss hypersonic travel in the upper atmosphere, using hybrid engines (SABRE). If you played Kerbal Space Program, you would have known about it. Also, the term 'aircraft' is both used in the singular AND plural form, you don't need to add an "s" to express it in plural.
Hey Lei, what about the SABRE hybrid rocket/jet engines, which will be used in the skylon space plane, how would they fit in this scheme?
Hey Lei, have you heard about the Reaction Engines A2?It takes the Skylon design, makes it way bigger, and strips out the rockets and oxidiser tanks. It can't go to space, but the engine precoolers allow it to fly way faster than conventional jets could.
Hope you guys like this one!
Can we make a system where we send stuff (products)
Similar to gas/fluids?
(Getting lets say pizza or gums from miles away. But packaged in a very fast highway-like pipe?)
Orrr.
Can we send stuff from country A to country B with BFR?
(Without getting destroyed)
Getting a high res tv directly from a country that makes it cheap.
Transporting foods and supply to stranded people asap
Sending troops across the globe in just 30 min. And give reinforcements directly from the homeland.
(Since it could have a rough landing. This'll be only used at clear/safe skies/bases)
Hey Lei, big fan of your videos here :)
So how about a BFS with no first stage. just a single sea raptor rocket engine, bigger wings and 2 jet engines under the wings but fixed to the belly for aerodynamics similar to fighter jets, then it would be performing the following:
1 - Horizontal takeoff from an airport runway and get to an altitude of about 12 000 m and Mach 0.85 just using the jet engines (efficiency)
2 - As soon as it is over the ocean or non populated area, it will turn off the jet engines and fire the rocket engine to get to Mach 6 or more, mostly to avoid generating the sonic boom over a populated area (speed and safety)
3 - After reaching a near space altitude (100 km), it will glide towards it's destination in a similar way the space shuttle did
4 - The jet engines take over as soon as the density of the air is at operating level, let's say 10 000 m to have enough oxygen for the ignition of the kerosene
5 - Land horizontally on an airport runway
What do you think? is this not a viable solution as something in between an airplane and a rocket?
Thanks in advance for sharing your thoughts ;)
Great Video! But please look up how to pronounce words like "Ente" or "heinkel". Thanks!
Unlike always, the thumbnail wasn't up to mark.
Where are ramjet and scramjet engines?
Awesome video. I actually researched kind of the opposite, of how to reach hypersonic flight without the use of a rocket engine.
The theoritical SABRE engine is also worth looking at as it is a hybrid jet/rocket engine, capable of switching between closed and airbreathing modes and uses hydrogen and oxygen which results in a high isp in space.
You were really focused on Concorde using afterburner to fly at high speeds, but the huge advantage that Concorde designers had was the way airflow was managed allowed Concorde to maintain supersonic velocities without afterburner. This made the transit portion of the flight far more efficient than other vehicles that need afterburner at that speed. The huge problem with Concorde was noise, this limited where it could fly, and for a long time was used as a reason to not allow flights to New York.
Hey today is my birthday....turned 16 today.......
Happy birthday
happy birthday
Happy birthday to all the 7+billion/365 people
Happy birthday bro..long live ahead
I think supersonic flight is kind of an unhappy medium between subsonic flight and space flight. A long haul airline can travel very far at subsonic speeds with reasonable seat mile fuel consumption. Super sonic flight takes much more fuel, a much more expensive aircraft, and still takes hours. The advantage that rocket planes have is that they can burn all the fuel at the start of the flight (even if the rocket engine is far less efficient than its air breathing counterpart), leave the atmosphere and fly to anywhere on just inertia. The BFR is definitely not optimized for point to point travel, but does seem feasible enough to possibly enter service in some capacity and open the door for other more optimized suborbital transport systems.
You are aware that a certain range of subsonic speed takes more fuel than supersonic ?
boboprime - really slow or really close to the sound barrier, sure. But supersonic flight always means a higher cost per passenger mile relative to modern-day cruise speed and altitude.
@@AmbientMorality
"But supersonic flight always means a higher cost per passenger mile relative to modern-day cruise speed and altitude."
That is actually not true. If you fly really high and rather quite fast, the fuel cost might be decreased.... or rather it will.
The question is really about configure the engine to work.... and well.. someone have already done that
Another great video Lei. You pronounced my name perfectly, but then it was the easy one!
Yes it is. Thanks for the support man!
The big difference is that a conventional rocket engine carries not only its fuel, but also its oxidizer (usually liquid oxygen.) That is a huge weight penalty for anything flying in the air, where we can just pull in air and use the oxygen in the air as the oxidizer. I know a company has theoretically been working on a "hybird air breathing rocket" that would use the oxygen in the air at low altitudes, and carried Oxygen at higher altitudes/space.
Upon some searching, it looks like it's still being developed: SABRE, being created for the Skylon Spaceplane concept. In theory, it could fly like Concorde in the atmosphere, then as it gets too high to reasonably use air for oxidizer, switch to carried oxygen and act as a rocket to reach orbital speeds/altitude.
I love your videos... The way you explain is awesome
But wouldn't that be pretty fuel inefficient?
what the video before commenting.
Yes, but it doesn't necessarily matters. If the fuel is lot cheaper and people willing to pay more for not having to sit in a plane for 10-15 hours, than it can work out. The BFR will use methane, which should be a lot cheaper. And I'm pretty sure most people really hate long flights, so they will be willing to pay more.
It will thats why fighter jets doesn't fly on afterburner too long, but there is ramjet and it's more efficent - blackbird flight on that all the time :).
Extremly fuel-inefficient - if you remember that the industry is whining about 4-engine aircrafts like the 747 or a380 its just not feasable to use a much more inefficient rocket engine
yeah very inefficient unless you can get it into space, then coast using zero fuel for most of the trip
I am interested in the use of retrofitted rocket engines on conventional aeroplanes to enable one-time-only VTOL or STOVL operations. The best example is the failed attempt at doing this on the C-130 for Operation Eagle Claw in Tehran in 1980. The videos are easy to find.
My question is: With 40 years of progress in both rocket engines and computer flight control systems - and with the disappointing limitations of the V-22 Osprey - is anyone revisiting this idea?
Rocket Engines are basically designed to get high thrust to achieve high speed that is the major purpose, but if we use rocket engines for commercial aircraft then :
- It would increase speed but less comfort simply because rockets stays at each section of atmosphere for short time interval but aircraft travels within a range of atmosphere so control and stability would be a challenge at those Mach Nos.
'Can we fly commercial Aircraft with Rocket Engines?'
?!! No but I'd like to see rocket engines on shopping carts or The Donalds back.
The gap in efficiency between rocket engines and jet engines is immense, even with afterburners engaged. The Concorde in afterburner flight at top speed managed around 3,000 seconds of specific impulse, while subsonic turbofans manage well over twice that number. The most efficient kerosene rocket engine ever produced (RD-0124) can only hit about 360 seconds in vacuum, where the most efficient at sea level (RD-181) is 312 seconds.
Very true. I don't think a rocket engine will ever be used for anything other than experimental atmospheric flight. The advantage of rockets is that they don't have to fight atmospheric drag or provide lift for hours on end.
afterburner is actually incredible fuel inefficient. And since air travel is a pretty price elastic market, I don't thinking it could work unless the payload it can carry is significant larger than turbofan based airplane.
On the other hand, typically thrust to weight ratio is much higher for rocket when compare to turbofan, so I guess if the cargo weight is high enough, it might be worth it as a cargo transport method. But it needs to be pretty damn high though.
Dude saw you in Block71, just letting know that you have a fan there! ;)
I'm a bit late, but I really enjoyed watching this video. Great job! (:
Hey thanks Losui!
Love your videos very informative keep it up
Wouldn't a proper compromise be something like spaceship two or something Bigger mounted on something like a Stratolaunch have it do a suborbital flight half way across the world, land, refuel and bolt it to a new stratolaunch and do that over and over?
Rockets carry their oxygen with them because they are flying in space where there is no oxygen. In the Earth's atmosphere it is smarter to use oxygen in the atmosphere. Theoretically it is possible to build a jet engine that is as powerful as a rocket engine.
Something like this: www.reactionengines.co.uk/
It's also possible to build an airbreathing rocket engine that can use atmospheric oxygen.
But that's really what the afterburner does. It basically turns the jet turbine into a rocket. More or less.
@@ALTruckerDad I have been thinking about this kind of engine which is basically like afterburning turbofan but it can switch from atmospheric oxygen to LOX. Working kinda like the sr71 engine but the afterburner also has LOX input so it could work in space.
Juho Mehtätalo
Why would you use a turbofan? They're only useful up to ~mach 2.
If your goal is to make a hybrid engine, then you want the atmospheric half of the engine to be practical across a wide range of speeds and altitudes. Some form of ramjet would be much more suitable, not to mention already the combustion chamber on a ramjet is already pretty close to a rocket and they don't have to drive a turbine.
@@lazarus2691 Do you know how the sr71 blackbird engines work? They start to use the afterburner like a ramjet when they get enough speed. It works by bypassing air straight to the afterburner. The engine could work like that. Then when it runs out of atmospheric oxygen it could start using LOX from fuel tanks.
And do commercial planes like AirBus A320 or Boing 747 use afterburner ?
Undefined.U Undefinned No and they don’t have afterburner. Also Concorde didn’t use afterburner for cruise.
What about the Sabre engine of the Skylon project? They talk about a possible spin off for the commercial flight industry. Essentially an airbreathing rocket engine, high speed (mach 2+) and no need to carry all that pesky oxygen around. Exactly what you were looking for this episode ;)
What about making it so the rocket engine fires for a few seconds and lets the plane glide?
Skylon!
They try to make air breathing rocket engines, has been developing this for over 30 years and says they’re done within five years. Static fire of individual parts are made, I think next step is static fire of the complete engine.
There is no reason to bring oxygen if it’s all around you. :)
There could be one application of rocket engines: high altitude flights. There is no oxygen and no drag, so it would make sense for long distant flight with very high speeds. Or at least might.
What about the use of scram jet engines. the efficient design of super sonic air intake could just offset the increased drag of super sonic flight?
What ot said at 2:53 to 2:56?
A factual error, you need to distinguish fuels from propellants. Kerosene is a fuel, ammonia is a fuel. LOX is an oxidizer. Both fuel and oxidizer make up the the vehicle's propellants.
One more thing that may have been worthy of appearing in your video is the SABRE, which promises to reach up to Mach 5.0 while airbreathing. Still in development though.
Hey Lei, big fan of your videos here :)
So how about a BFS with no first stage. just a single sea raptor rocket engine, bigger wings and 2 jet engines under the wings but fixed to the belly for aerodynamics similar to fighter jets, then it would be performing the following:
1 - Horizontal takeoff from an airport runway and get to an altitude of about 12 000 m and Mach 0.85 just using the jet engines (efficiency)
2 - As soon as it is over the ocean or non populated area, it will turn off the jet engines and fire the rocket engine to get to Mach 6 or more, mostly to avoid generating the sonic boom over a populated area (speed and safety)
3 - After reaching a near space altitude (100 km), it will glide towards it's destination in a similar way the space shuttle did
4 - The jet engines take over as soon as the density of the air is at operating level, let's say 10 000 m to have enough oxygen for the ignition of the kerosene
5 - Land horizontally on an airport runway
What do you think? is this not a viable solution as something in between an airplane and a rocket?
Thanks in advance for sharing your thoughts ;)
emir h.a The BFS is not designed to land horizontally, you’re better off developing a brand new platform rather than cannibalising a vertical launch system.
I agree with you. but we are already supposing it has bigger wings and 2 jet engines, so it wouldn't be too hard adding some wheels to this new design ;)
Frankly speaking, the BFS in my example is not meant to be a replica of the actual BFS, it's more of a basic idea of little modifications that could get us supersonic passenger planes borrowing the efficiency of jet engines for the first phase of getting off the ground at subsonic speeds, then getting the speed of a rocket once it is in the right conditions.
I see no reason why the BFS wouldn't be able to perform a horizontal landing, I believe its carbon fiber fuselage is more than capable of supporting its weight on landing gears.
The only reason the BFS was designed to do a vertical landing is for landing on the moon and mars where you have no or little air density to give lift to the wings. But since this video is about intercontinental travel on earth, a horizontal takeoff and landing make more sense and is way safer and smoother from a G forces point of view.
What do you think?
emir h.a I think it’s pointless. It isn’t aerodynamically designed to operate like an aircraft. If something is going to operate like an aircraft, the base design should be an aircraft.
You need like 20,000km/h for a suborbital hop. Jet engines can give you like 2500. And it's even worse for altitude. Jet engines don't work well above 20km, and you have to go over 100km.
And if you only go supersonic over oceans you lose a huge amount of time. That was one of the reasons why the Concorde failed.
What you want is the Sabre engine. That's an air-breathing rocket engine.
Henry Stitt I disagree with you because of the following:
An aircraft and a rocket are both cylinders meant to resist the negative air pressure at high altitudes, in the current case the BFS is built to withstand higher pressure differences as it is built to fly in the void of deep space while offering its passengers the same level of air pressure as what they would get on earth. So the BFS has a more solid cylinder, making it an excellent airplane frame which would better resist the effects of repeated compression and decompression.
The aerodynamics of the BFS are already designed for hypersonic speeds, so only the wings need to be redesigned for providing more lift on subsonic speeds and much slower speeds for taking off and landing.
Why you chose concord? Tu 144 was both faster and first model to achieve the feat.
Ramjets and Scramjets are the solution to faster jet engines. With the use of a Scramjet we can theoretically get speeds up to Mach 10. The famous SR 71 Blackbird used a ramjet engine for its high speed.
Yo, you forgot the continuing research on hybrid rocket-jet engines. The SABRE Engine and the Skylon Spaceplane
You won't even need after burners to go over mach one. Because of the improvement of aerodynamics
What about the P&W J58 or a comparable turboramjet? To me it seems like the way to go if you want to achieve efficient supersonic or even hypersonic travelling.
Not really. The first problem is that it requires a completely unique logistics network and that's insanely expensive. Even the US military found it too expensive.
The second problem is extreme temperatures. Which mostly causes the first problem. Plus SR-71 pilots had to wear special air conditioned suits to stay alive.
The third problem is aerodynamic forces. At hypersonic speeds if your plane isn't aligned perfectly it breaks into million little pieces instantly.
If you want to fly fast it's best to avoid the atmosphere.
András Bíró Agree on that, but even the best afterburning turbofans reach their limits at about Mach 3 (MiG 25, R-15B-300), problem being that the rotors start melting. Only options at this speeds ar RAM- or SCRAMjet engines. Those obviously have the problem of not producing thrist at subsonic speeds. When thinking about having a RAMjet and a afterburning turbofan you get the problem of it getting too heavy. rocket assisted ramjets and scramjets, which use decoupling disposable rockets will soon work, but are extremely expensive. The only option left would be a turboramjet comparable to the J58. Of course, nowaday that thing would not be viable, but I‘m pretty sure it would be possible to develop an engine that is better in any way possible.
András Bíró About the cooling problem, I don’t know too much about how to solve that but I‘m sure there is a way.
And about the aerodynamic forces, even at hypersonic speeds it’s possible to build selfstabilizing aircrafts. They would probabely be really unstable at low speeds, but that can be handled.
Those problems could be solved potentially, but it's unnecessary, there are better solutions.
1. For short range (~1000 miles or less) the Hyperloop or something similar is the best, or even regular high-speed train.
2. For medium range supersonic electric VTOL planes. The huge advantage is that they can go way much higher and much faster than jets, because they don't use that delicate combustion process. Flying in less dense air also means they have to use less energy. This isn't just saving money, but makes the whole thing possible, because batteries have much less energy density then jetfuel. In less then 10 years this will be possible.
3. For long range rockets can be the best. They won't necessarily be cheap, but nothing beats their speed. Pure rockets may be wasteful, but they are simple and available now, and if they are reusable and their fuel is cheap, it doesn't matter much if they are wasteful. Later we could use something like the Sabre engine.
And if you want fast but dirt cheap long distance travel, orbital rings are the solution. As a bonus they can take you anywhere in the solar system for little additional cost.
András Bíró I agree on the hyperloop, but I don‘t see supersonic electric planes in the closer future. Batteries just don’t get the energy density necessary. And with rocket I still think the pure fuel mass burned is too high.
I think that a rocket powered plane uses more fuel than a vertical rocket, as it must constantly burn. Rockets can turn their engines off quite easily
There is something much better than afterburner - ramjet. It's more efficent in high speeds, blackbird used that and the "next concord" will also use this technology.
Great presentation bro
CONCORDE IS THE MOST BEAUTIFUL AIRCRAFT EVER MADE
Retired,but i can't think of another aesthetically appealing aircraft
I've been on Concorde several times. Really beautiful aircraft.
you seen the SR71?
We do already
In ksp
Not a leopard and sas
@Not a leopard you mean "moar" :p
The key is a phrase you didn't even use: Air breathing engine. An engine like the Blackbird uses would be a way to power near hypersonic flight and challenge bfr.
Brother, I did use. Watch one more time pls
there is also scramjets and ramjets. Biggest problem with supersonic flight is no country will allow it over land until something can be done to soften the sonic boom(NASA is actually studying this). If we could find a way to make supersonic or even hypersonic flight over land viable in both boomyness and fuel/seat ratios you could have even short flights from NYC to Asia.
As for E2E BFR... I think it is 100% possible and workable from an engineering perspective. Business wise it would need a good case for cost, But equal to a first class international flight ticket would probably be viable. Even more so if business class prices.
However engineering and business are child's play compared to the ultimate barrier for inter-city BFR and that is policy surrounding launch and landing pads. SpaceX would have to deal with multiple nations and cities on this and red tape and NIMBY are forces that cannot be fixed merely with lots of very intelligent people. Rocket Science being a Science functions on logical outcomes, Dealing with governments is like trying to herd cats through the testing department of a laser pointer factory.
Can it be opposite by flying rocket's with airplane engine (with sea as well as vacuum engine)
What about research in scramjet/ramjet? If pure speed in atmospheric flight is the goal ;)
In case of physic, answer is yes. In case of economic, answer is no. That's the same thing as why we don't put F1 engine on the public bus. It's technically can be done but not economic viable.
So, not even an aircraft that stays just sub orbital and hits rediculous speeds by accelerating in an area where there is very little atmosphere using rocket engines is a remote feasibility?
Maybe use Reaction Engine's SABRE engine to a commercial plane?
There is a SABRE aircraft concept with no oxygen but with 4 engines, in the 300-400 seat range with a top speed of 5500km/h. It would use only Hydrogen.
And its possible that hydrogen is getting cheaper than fuel in the future
Time = speed and space = information storages.
Really cant have made much research on this topic. There is two HUGE parts missing.
1: Air density.
2: Air breathing rocket engines.
1: The higher you go, the less dense the air are. This limits the effectiveness of a engine. A commercial engine is REALLY efficient at 12 000meter. But it don´t even work at 20 000 meters.
A engine made for 20 000 meter will always be less efficent, but the air is less dense, making the aircraft more efficient in total. For sub sonic aircrafts this effect is very smal. Making 12 000meters pretty much a optimal altitude for sub 1000km/h aircrafts.
But for 2000km/h altitude aircraft 20 000m of altitude is much more efficient.... and well that is exactly what Concorde did.
For 3000km/h, higher altitudes are needed, about ... well 30 000 meters. And well, here is the SR71. Well 26 000 meters and 3500km/h.... officially. (worth noting, SR71 is much larger than most people think... longer than a Boeing 737-100)
If you go higher, you become more fuel efficient. But there is a problem. 30 000meter is pretty much the limit of what a Jet engine can work. YES a afterburner can work at higher altitudes, but if you don´t have a Jet to keep it lit.... well... it don´t matter... it wont work.
Now, there is a way around this. And ..now this is what makes it real interesting. It makes the aircraft faster AND more fuel efficient.... well of sorts.
Scramjet.
en.wikipedia.org/wiki/Scramjet
Its pretty much a afterburner only engine. And it turns out, if you fly sufficiently high, and sufficient fast, the low fuel efficiency of the afterburner is totally offset by the low drag of the very high altitude. This is sort of a oddity, because the faster you go, the more fuel efficient it gets. The scramjet does have one significant drawback. Sort of a deal breaker. It don´t work under 2,5 mach. It have to have a secondary engine... and well, while the scramjet is very light... the secondary engine.. will not be.
That gets us to point 2.
Airbreathing rocket engine... While this was considered a theoretical engine just a few years back. The first actually working version was tested a few years back... and.... i say wow, does that engine have a sexy start up sound.
ua-cam.com/video/wxdXLl9P62M/v-deo.html
While this engine is not as efficient as a normal turbofan engine att normal speeds or altitude, its really not as inefficient at most other. It even give the concorde run for its money at its home turf.
This engine got twice the weight to thrust as a commercial turbofan. This make it incredible strong. While its not very efficient at lower than 20 000 meter altitude. It will only take about 5 minutes to reach that altitude. At about 30 000 meters it can reach mach 5, and do that VERY efficiently.
But the saber have one more trick up it sleave. It can also run on close cycle with oxygen. This is really smart. Because it can still get to 30 000 meters and 5 mach on air. Then swich to oxygen and have a very efficient rocket engine. When it does that it increases the thrust by 50%, as well as being (for a rocket engine) very efficient, with a ISP of 460, that is almost 50% more efficient than the SpaceX rockets. The rocket engine can be used to boast the aircraft up to 70-80km where the air is so thin that there is virtually no air resistance, then it can glide back to earth using no fuel what so ever running at 10-15 000km/h.
The great thing about this is that the oxygen is the heavy part of the rocket. Using oxygen for just a minute or two to accelerate. This make it possible to both go London to New York in a hour. Or ho London to Sidney in two hours in "space mode" (With a bit less cargo capacity). The nice part about this is that going space mode is even more efficient then going
What about ramjets though?
Changing the design of the plane and consuming LOX and Liquid Hydrogene at a lower rate than rockets could be done ? It will be clostly but possible?
Imagine minding your own business and then a FUCKIN ROCKET POWERED 747 SPEEDING ABOVE YOUR HOUSE AT MACH 4 BREAKS YOUR WINDOW AND EARDRUMS.
Yeah there's a reason why airlines cant even go supersonic....
Just too loud
Really, the Okha rocket plane was envisioned as a one-way Kamakazi platform. It's limited range doomed it. But in Germany, the Messerschmitt 163 Komet was a success, as least technically. It should have been in your timeline.
Exactly. It may have been built after the He 176, but it still used solid rocket motors, and was technologically much more primitive. There's no reason to include the Okha on a timeline of rocket planes. The Bell X-1 would have been a better step between the He 176 and the X-15, though as you noted the Komet would also make a good example.
Jets have wings to fly cross ways Rockets are built to fly up you see the technology in your fireworks on the 4th of July
If there could be a safe all in one rocket fuel, that could eliminate the need for carrying liquid oxygen, then the weight problem could be solved.
Before i watch, i would say no because rockets are too inefficient to be used in an atmospheric environment for a long period of time. The engines are also sometimes quiet heavy and bringing all that fuel will bring down the useable payload size of an airliner.
Put afterburners on turbofan engines
2:45... Well its air that sucked in.. not oxygen...
what happen if i forgot my dashlane password?
Great video. One bit of advice. It's aircraft and fuel. Not aircrafts and fuels.
Wait, you forgot the Me 163, are you nuts?
Hmm ... I feel like this video is missing Sabre and Ram/Scram-jets...
If we can get planes up to speed with rocket engines we can use ramjets.
Can we fly space rocket with commercial aircraft engine ?
or atleast until they cant run anymore
Doesn't help much. The flight ceiling of a turbofan engine isn't very high relative to orbital altitude, and it isn't traveling very fast relative to orbital velocity.
"Ente" means "Duck" in German
"Ente" is german and means "duck" by the way
The faster you go the more unstable you get
And what about ram-jet-engines ?
Thank you Lei.... You spell my name correctly,😉
surprised you didnt research the Skylon Space Plane??
And what about hypersonic engines?
Should've ended the video on 3:30
If they would not use liquid kerosene in rocket engines it would be a environment friendly option for airplanes👍
don't forget the x-15 disaster...
The speed you quote seem to be in atmosphere. Rockets work best in space (they even carry oxygen) and aircrafts work best in the atmosphere. Compare a both strengths before coming to a conclusion..
I’ve contemplated ending my life during long haul flights, so I’m willing to take the risk.
So let's use Hyperloop for fast transportation 😁🚇
I thought Concord was too loud.
It was. That's why it was restricted to one or two routes.
And the SABRE engine?!
Ente, the first plane with rocket engines is german and means duck
rocket engines are for more speed, there could be jet-rocket hybrid engines
Don't conflate "commercial" aircraft with airliners. Not the same thing.
It can be used if you are willing to takeoff from earth stratosphere
Short answer: no.
Long answer: nnnnnnnooooooo.
Simple answer: nah.
Simple answer in German: nein.
Complex answer: 1- turbo prop are the most energy efficient, then jet, then rockets. Why? Because props and jets use the atmosphere as reaction mass, the stuff that gets thrown backward to create a force by Newtons laws of motion. Rockets fight the atmosphere with its own fuel as reaction mass.
2- economics. The Concord proved that passengers will opt for cheap, slow and comfort. Concord was fast and sexy but it was hecka expensive and cramped uncomfortable. For the price of a cramped Concord seat you could get a first class seat with champaign, gourmet food and loads of legroom on a jet liner.
3- safety. Rockets have about 5% failure rate. In manned flights rockets have killed 1 in 31 space travellers. If airliners had a similar death rate they'd be killing tens of THOUSANDS every single day.
Rockets are for getting to and moving around in space. Aircraft can't. We should use rockets where they are the only option. We should use jet and props where they reign supreme... in the atmosphere.
I bet , once over 40k ft when jets start losing eficiency, should start rocket engine, and get higher and lose air resistance and go faster
What's with the 18th century music??
tatal mass ?
A shout out to the russians,their shuttle could drop out of orbit and fly on jet engines.
Ten degrees Fahrenheit minus ten degrees Fahrenheit above and below zero
This is all completely wrong.
1. The Falcon 9 first stage reaches 8000km/h. That's already far faster than any airplane ever. But the second stage can go over 30,000km/h. That's like 20x faster then the Concorde.
2. Supersonic passenger planes don't exist, and likely won't exist any time soon. The problem is cost and more importantly noise pollution. Rockets make even more noise, but it's very contained.
3. Rocket engines can be more reliable then jet engines. They are a lot simpler and work for a few minutes instead of many hours. Historically they weren't safe only because they were one use only and saving mass was essential. That's not the case with the Falcon 9 or the BFR. Their engines are designed to be used many times, especially the BFR engines, which already implies much higher reliability. But reusability brings down costs so much that engineers can "waste" precious mass on safety margins. The Falcon 9 had over 50 launches, and each one uses 10 Merlin engines. That means around 500 engines were used so far, many of them flew twice and landed twice. Of all of these only one engine failed, and that was on one of the earliest missions. And even then the rocket reached it's intended orbit and released it's primary payload on the desired orbit. The BFR is designed with even more redundancy. The booster and the ship too will be able to safely land with multiple engine failures.
4. Rockets are actually less vulnerable to bad weather than planes. That's because they don't rely on big wings and external air supply. Landing a plane is a very delicate procedure, many things can go wrong that result in a disaster. A sudden change of the wind is enough to crash a plane. Rockets don't have wings, and their round shape is the best to resist wind. The BFR has aerodynamic surfaces, but much relatively a lot smaller than plane wings, and it's powerful engines and reaction control system can counter the forces and it's computers can react to wind changes thousands of times faster than human pilots. Plus their order of magnitude shorter trips allows them to know the weather at their destination with a drastically higher accuracy. Also planes need to land at high speeds and use tire traction to stop safely. If the tarmac is slippery, they might not be able to stop. That happens often. Rockets brake with their redundant engines in the air, and touch the ground gently. You can land a rocket on any small, reasonably flat and stable surface. You can land them on ice, deep snow, sand, mud or anything as long as they don't tip over. By the way, icing is another big issue in aviation. Too much ice on the wings and they don't generate lift. Or your essential external sensors can freeze over. Rockets don't need to generate lift, and don't have external instruments. In fact, since many rockets use cryogenic fuel, which pretty much guarantees a lot of icing, and that doesn't seem to cause problems.
5. Rockets are less vulnerable to collisions too. Birds strikes can kill a big jet engine, but rockets engines don't have to suck in air, so they are immune. When the rocket flies forward it's aerodynamic shape can easily deflect birds, and during landing, when they are low enough to encounter birds, their engines are firing, so they simply blow away birds. And even if a bird hits an engine bell, it's far less delicate then the internals of a jet engine. In a jet engine the turbine blades are rotating at extreme speeds, so any small imbalance makes them explode. Rocket engines don't have such exposed moving parts. Rocket engines are also immune to dust, water and hail, again, because they don't have to suck in air. Since rockets fly precisely on predetermined trajectories, they won't collide with each other, and since they fly through the path of other aircraft vertically in very specific small areas, it's again very easy to avoid collision.
6. Rockets land in a few seconds, and don't need much space for that, so there won't be congestion around spaceports. They can even land close to each other at the same time, as we saw it with the Falcon Heavy side boosters. The traffic on and around large airports is insane, and that's often causes disasters. Not having to deal with that is a huge benefit.
7. This all also means that delays will be far less frequent.
András Bíró
Thank. You.
You just described everything I wanted to say about this. Kudos.
3. "A lot simpler"? Turbopumps are in harsher steady-state conditions than aircraft compressors and during thrust transients the conditions are ridiculous. These severely limit life, particularly compared to much gentler startups of turbofans. Now consider that the fatigue on engines like CFM56 is primarily due to transients from idle to takeoff thrust and back - not the flight hours at cruise. When a rocket engine has to do multiple, harsher startups over a single flight, it will require more maintenance and care.
500 engines running for a combined 60 or so missions is about 35 total flight hours across the Merlin family.
4. Unproven. And what do you even mean "this happens often"? Planes do not fail to stop on the runway "often". De-icing is not difficult; it's another logistics challenge and rockets will have their own set of logistics challenges. Also, landing in mud or deep snow or whatever fifty scenarios you have would be undesirable from a logistics standpoint. Still need to get things (passengers, propellent, etc) to the rocket.
5. Probably true but bird strikes don't happen often enough for it to significantly affect engine lifetime.
6. They need spacing for safety, just like airplanes. Also, they need to be reasonably far from passenger terminals for the same reason that runways typically are separated a decent ways from the terminal. Also, where are these disasters that happen so often? There's a rare incident, its not nearly as frequent or dangerous as you seem to like to make it sound.
3. Yes lot simpler. The operating conditions are a completely different matter. Turbo pumps may experience worse conditions, but for much shorter times, and it's way much easier to design them to withstand those conditions than to make a much more complex machine reliable. Flight hours don't matter, the number of missions do.
4. If you are familiar with plane crashes it's very easy to see why it's true, and I explained it too.
5. Killing the engine instantly is in my book is a significant effect. While engines can survive ingesting small birds, lager ones or multiple hits are much more dangerous. en.wikipedia.org/wiki/Bird_strike#History_of_incidents
6. Large planes have to be separated by minutes due to wake turbulence. Rockets don't have this problem. As I said we already saw simultaneous landings closer to each other than the length of a short runway. Planes need a lot of space to land, rockets don't. The Falcon 9 can already land within a few meters of the center of the landing zone. The BFR will land with centimeter precision. The problems are noise and safety. Both can be solved in several ways. For example by surrounding each landing pad with very thick sloped reinforced concrete walls.
3. I grant that flight hours are not all that important (I said that in the first part of my answer). As you said, flight hours are less important than engine cycles; transient conditions on a turbopump are way worse than any airplane engine so this severely limits lifetime. I don't know how it's "way much easier" to design turbo pumps to withstand these conditions; you have an order of magnitude higher thermal loading, much higher angular velocity (due to much smaller turbine), and, if anything, even more restrictive mass conditions.
4. Runway overruns are ridiculously uncommon. De-icing crashes are very uncommon, especially with the number of techniques developed to make sure that can't happen. I am familiar with plane crashes, and the core fact is that they don't happen very often at all.
5. Sure. But almost no engines ever ingest a bird. Overall, the fact that some very small percentage of engines have their lives cut short does not significantly affect the total engine lifetime.
6. Build a runway parallel to the existing runway. Capacity issue resolved. Yes, this takes space, but we already have accounted for this space in airport design. I'm not sure how very thick sloped concrete walls are supposed to make a rocket engine or a sonic boom any quieter, unless your very thick sloped concrete walls are also a few kilometers high.
3. It's a lot easier to make something stronger than to figure out and prevent all the ways a complex machine can break. It doesn't matter how bad are the conditions, we know exactly what they are, and we can easily test whether the turbopump can withstand them. It's way harder to map and test all the intricate ways that thousands of components can interact with each other. And turbopumps are in an fully controlled artificial environment, while jet engines are exposed to the outside world and it's infinite amount of different conditions.
4. Plane crashes are ridiculously uncommon in general. I mean when a plane crash happens, the leading causes are pilot error, weather and mechanical errors. Rockets are flown by computers, and don't experience the complex situations that require human pilots in planes. Rockets don't care too much about weather either. That's where runway conditions, icing, wind and other stuff comes into play. And rocket engines are a lot simpler, work far less between inspections, and can be more redundant too.
5. Again, plane crashes are extremely rare in general. And to keep birds strikes from being a major issue requires a lot of hard work. Airports use a ton of different methods to keep birds away, and jet engines are designed to survive most bird strikes. Still, accidents happen. I'm not saying that this is the worst problem in history, but it's a problem and rockets are immune to it.
6. Space is exactly the issue. Not just on the ground, but mostly in the air. Since flights can't be scheduled perfectly, planes have to be juggled by air traffic controllers in real time, and it's the worst around major airports. This is one of the biggest problems of aviation right now, and limiting the amount of traffic airlines and cities can handle. Expanding airports, even when possible is extremely expensive, and takes several years. Rockets fly in and out of spaceports vertically, so they can be far more densely packed, and don't interfere with each other. And the short and very predictable flights allow them to reserve a landing spot before takeoff. And it's necessary too, a rocket can't really wait for it's turn once it's launched. The wall's don't have to be too high, if the passengers aren't out in the open. The concrete walls are needed more against flames, hot gases, and possible explosions. Against noise simple sound proofing can help too. There are several possible ways to do it. The simplest is something like the bridges big airports have. Just much more robust of course. Or another way is to synchronize landings and launches and move people in and out in between them. It could be a complex logistical problem, but probably can be done. Or you can even use underground launch pads. ICMBs are routinely launched from underground silos, and the Falcon 9 already lands precisely enough to fit in a tight hole. Then you can just close the lid on them and the passengers are perfectly safe. Two rockets flying close to each other still could be an issue, but it's avoidable since they spend just seconds near the spaceport. And again, good sound proofing can drastically reduce the problem.