Boeing Unveils Hypersonic "Son-of-Blackbird" Demonstrator Design

a reply to: Zaphod58

I hate to be such a pain in the ass tonight.. just thinking out loud.

But i highly doubt the drag or weight arguments.. They payload/energy of aircraft is rather efficient when up to speed.

And drag... hmm some clever design could eliminate a lot. Even the Germans had already in wing engines the WWII Horton 229 had already solved that.

And i took the liberty of making a rough drawing to split the front drag... a valve would do the trick.
Think one outlet being a conventional jet
The other being a ram or scram jet


Edit: I do appreciate the link you posted! A lots of info i did not hink about

a reply to: EartOccupant

Engines that are embedded in the wing also don't have things like afterburners, which limits them to subsonic propulsion. If you were to try to put an afterburner into a design like that, you'd damage the rear of the wing. Every in wing engine, such as the Ho.229, and B-2 were non-afterburning, engines. You need something capable of a lot more acceleration to get up fast enough to ignite a scramjet/ramjet engine. A true ramjet requires in excess of Mach 3, and closer to Mach 5 to ignite and operate.

The engine might be efficient when it's up to speed, but you have to get it up to speed to get that efficiency. To do that you have to minimize weight and drag. Look at the SR-71. It was a very flat, very thin design to reduce the drag as much as possible for the ability to travel at high speed. You can't have four or more engines, and excess drag and weight to do that.

As for the weight, a TBCC puts both engines into one housing. If you were to put separate engines in, you would require a bigger platform, which would make the overall weight heavier, as well as having all the required parts for the separate engine from fuel lines, to intakes. That not only adds weight, it adds tons of complexity to the design.

a reply to: Zaphod58

Very interesting. Top!

I guess they are designed around an specific altitude window as well.

I wonder if air liquefies at those speed/pressures.

a reply to: Zaphod58

so in the tbcc the scramjet is like a bypass duct that goes underneath the turbine where the fuel is ignited and shot out the back. wouldn't you need to change the inlet shape as it transitions from turbine to scram jet mode to keep the compression up? sounds difficult. i can see why they are struggling with hypersonics. they need breakthroughs in inlet design and compressors.

a reply to: BASSPLYR

There is write up over here at Popular Mechanics with twitter photo: "Son of Blackbird": Boeing Reveals Hypersonic Concept That Could Replace SR-71.

The photo is nose on. Not sure if it is any different than the one you mention as I did not sign up for AW either.

I find it funny that there was a lot of speculation went into parsing what was said about Lockheed's version just the other day (the article essentially parsed the verb tense of what was said to speculate LM may already have built an SR-72! Verb tense!). Now this from Boeing. If it were any other companies I would have been, meh!

You got to love a little competition!

a reply to: BASSPLYR

That's one of the harder things about it. A turbine requires subsonic air to operate, and can only operate up to the mid Mach-2 range. You can squeak that up somewhat, but not a great deal. A scramjet can operate with supersonic airflow, which makes things interesting. You have two engines that operate at the extreme ends of the spectrum using the same inlet. Bitch and a half doesn't even start to describe it.

a reply to: Zaphod58

how bout a ramjet like the sr71 mixed with a scramjet. that could get you up to mach 3ish and then try for the scramjet. i know a ramjet still isn't really fast enough to get it up to upper mach 4ish to get scramjet going but maybe some zip fuel like boranes to give it a little more speed to engage the scramjet. not a perfect solution but what else could one do. rocket assist maybe? seriously why not just have disposable rockets to assist to the hypersonic mark for the scramjet to take over.

a reply to: Zaphod58

Maybe being too smart for my britches...

You'd need a high temperature skin, probably ceramic or ceramic composite, as high speeds, even in high atmosphere would heat up. Which brings up the idea of skip-glide. You get enough altitude, glide for a bit, let friction take hold as you drop into the lower atmosphere and you pick up speed. Hit you Mach 3-4 marks, sramjet back up into a higher flight level, and repeat until you are on the other side of the world!

In theory, that sounds super cool! In an actual air frame with real, turning parts? Reminds of Steve Austin's roll in the desert waiting to happen... only at high altitude! That is where all the automation would needed. That is all weight. Which again, adds to the engineering nightmare!

originally posted by: BASSPLYR
a reply to: Zaphod58

so in the tbcc the scramjet is like a bypass duct that goes underneath the turbine where the fuel is ignited and shot out the back. wouldn't you need to change the inlet shape as it transitions from turbine to scram jet mode to keep the compression up? sounds difficult. i can see why they are struggling with hypersonics. they need breakthroughs in inlet design and compressors.

Advanced materials science is the key to success here. Imagine a material that can:

• Withstand the extreme heat at hyper-sonic speeds
  
• Can actually change shape using electrical impulses only (no extra weight of additional hardware)
  
• Is resistant enough of the advanced fuels burning to get up to hyper-sonic
  
• Is resilient enough to last more than a single flight
  
• Can be grown quickly from the atomic level in existing facilities
  
• Costs less than the GDP of a small country to produce
  
• Can be used to construct a TBCC engine that changes shape based upon dynamic requirements
  

a reply to: Zaphod58

I'd be curious to see if that Chinese spaceplane is real and what they are using.

Scramjet engineering out in the public for nearly 40 years. Hummm maybe it's just a cover for something already flying.

Just a thought

a reply to: BASSPLYR

A scramjet is a ramjet. In a ramjet, they use diffusors to slow the incoming air to subsonic speeds before entering the combustor, then it's accelerated to supersonic speeds out the exhaust. In a scramjet, the air is slowed to a lower Mach number, but stays supersonic all the way through the engine. Like the Ramjet, it's accelerated to higher speeds after the combustor. A scramjet keeps a more uniform temperature though, so it doesn't require quite as bad thermal management as a ramjet.

Drag is one thing...The other negative on speed is weight...

a reply to: mikell

No, it's just really damn hard. It's one thing to get a Mach 3 aircraft going, but once you start adding Mach numbers to it, the it becomes exponentially harder, the higher you want to go. I read something once that said the equivalent of "We can afford Mach 6.5, but if you want Mach 7, we're going to lose our budget for the next three years, to get two of them".

a reply to: Blackfinger

Which is why you want a TBCC.

a reply to: Zaphod58

wouldn't all that extra material tto make the scramjet duct add unnecessary weight. why not just make a scramjet that works at slow speeds too. like using louvers or an iris inside to force the air in smaller spaces compressing it more. they dilate as the engine pushes faster letting more air in at the right compression ratio.

or what about just a new nozzle to compress the exhaust as it comes out. kinda like how those spray nozzles you screw on to garden hoses make the pin close up the nozzle forcing the water out at higher pressure?

a reply to: BASSPLYR

Ramjets need to be above a certain speed to work pretty much at all.

a reply to: BASSPLYR

As anzha said, you can't. There is a low speed ramjet, but it can't go from 0. It requires air to be flowing through the engine to ignite the fuel.

a reply to: BASSPLYR
Helium pockets deep in the airframe structure?

Damn!! The last several posts are why I love and stick with this forum!!! Thanks all for some very good (great!,) reading.