Boom Supersonic Overture M1.8 SST

[TomcatViP]

That isn't a smoke generator at the wing tip, it's an exciter so they can test for flutter at lower speeds by exciting the wing for how it would react at higher speeds. It allows for a safer expansion of the flutter envelope.

That is correct.

This detail being revealed recently by Boom in their press briefing.

 

[TomcatViP]

Those aren't the tufts either, those are the pieces of tape holding the tufts (tufts are visible in a hi-res photo). If those were the tufts, they'd be indicating world-beating span-wise flow.(Which is what I first thought!)

I have no more that Falcon eyesight but still I can see some of them enough to have placed my earlier comment

It would be nice not be taken for an imbecile at face value.

And some updated graphics from link in post below:

 

[Flyaway]

View: https://www.youtube.com/watch?v=lQvQsvD4Ykw

The first ever look into Boom Supersonic, captured during last Friday's XB-1 flight 3 on S3. Get an up close look at XB-1, the moments before takeoff, and test pilot "Geppetto" re-opening the cockpit and sharing his unfiltered thoughts with Blake right after flight.

 

[aim9xray]

It would be nice not be taken for an imbecile at face value.

No disrespect was intended, my apologies. I made the imbecilic assessment at first, scratched my head, researched it, and thought I might share with others who might have the same initial misapprehension as I.

 

[Sundog]

Those aren't the tufts either, those are the pieces of tape holding the tufts (tufts are visible in a hi-res photo). If those were the tufts, they'd be indicating world-beating span-wise flow.(Which is what I first thought!)

I was going on what Blake Scholl, the head of Boom posted on Twitter. But with the tufting, smoke generators do make more sense.

 

[Scott Kenny]

Sure, but you could add an afterburner or cold stream burner for acceleration and then cruise supersonically more efficiently than with a smaller bpr like the F119. Of course you would have to integrate the larger fan into aircraft structure.

Oh, absolutely you could add an afterburner or PCB/cold stream burner to get supersonic. But even the mighty Blackbird (all hail the king of speed!) needed a small dive to break Mach 1 with the afterburners lit. So there's no huge reason to add the afterburners to a design if they don't give you massive acceleration. Just dive from 40k to 30k and then level out and climb back up once supersonic.

 

[Basil]

Oh, absolutely you could add an afterburner or PCB/cold stream burner to get supersonic. But even the mighty Blackbird (all hail the king of speed!) needed a small dive to break Mach 1 with the afterburners lit. So there's no huge reason to add the afterburners to a design if they don't give you massive acceleration. Just dive from 40k to 30k and then level out and climb back up once supersonic.

I was thinking of a military application of the "Symphony" engine. Depending on the situation and mission you sometimes want sudden acceleration without a dive. The SR-71 did the dive to preserve fuel for the reconnaissance mission.

 

[Scott Kenny]

I was thinking of a military application of the "Symphony" engine. Depending on the situation and mission you sometimes want sudden acceleration without a dive. The SR-71 did the dive to preserve fuel for the reconnaissance mission.

I'm not really seeing a military application for the engine, barring a slower blackbird or maybe a really large cruise missile (Hound Dog or SLAM sized).

It's just going to be a weird engine. Massively flat-rated so that it's not too loud on takeoff and with a really low OPR for supercruising.

 

[Basil]

I'm not really seeing a military application for the engine, barring a slower blackbird or maybe a really large cruise missile (Hound Dog or SLAM sized).

It's just going to be a weird engine. Massively flat-rated so that it's not too loud on takeoff and with a really low OPR for supercruising.

In case the engine is ever realized and works as proposed - I can imagine there would be several military applications for an efficient Mach 1,5 (or so) supercruise off-the-shelf propulsion system.

 

[Basil]

Some - related to this topic - considerations regarding civil supersonic propulsion - excellent by Bjorn as always:

Bjorn’s Corner: Supersonic transport revival, Part 10 - Leeham News and Analysis

October 12, 2018, ©. Leeham News: In the last Corner we discussed the challenges of the nacelle outlet for an SST (SuperSonic Transport). Now we will discuss SST engines and what are the key technical challenges for these... Read More

leehamnews.com

Perhaps we should move this to the Propulsion Section.

 

[NMaude]

cold stream burner

Are they like the front-nozzle plenum burners for the BS100 engine designed for the aborted HS P.1154?

 

[Kiltonge]

For comparison, tufting on the wing of a Skylancer ( NASA TN D-3071 ):

https://ntrs.nasa.gov/api/citations/19660003728/downloads/19660003728.pdf

The XB-1 appears much better.

 

[F119Doctor]

Some - related to this topic - considerations regarding civil supersonic propulsion - excellent by Bjorn as always:

Bjorn’s Corner: Supersonic transport revival, Part 10 - Leeham News and Analysis

October 12, 2018, ©. Leeham News: In the last Corner we discussed the challenges of the nacelle outlet for an SST (SuperSonic Transport). Now we will discuss SST engines and what are the key technical challenges for these... Read More

leehamnews.com

Perhaps we should move this to the Propulsion Section.

Bjorn is correct in stating that compressor exit temperature T3 can be a limiting factor, just like turbine rotor inlet temperature T4.1, low rotor speed N1, and high rotor speed N2.

The response of the engine control system when reaching one of these limits is to stop increasing core fuel flow, or reduce fuel flow as necessary to keep at or below the limit. This reduces the aerodynamic rotor speed of the engine, reducing airflow, pressure ratio, and thrust. In supersonic flight, increasing inlet temperature with greater speed causes all these parameters to increase until one of them hits its limit (called the Theta break), with increasing inlet temperature causing loss of engine performance beyond that point. The total propulsion system performance can continue to increase with inlet ram recovery multiplying the engine pressure ratio for greater nozzle pressure ratio, but the engine contribution decreases beyond that limit condition.

 

[TomcatViP]

And what about having a blown fan instead

 

[Scott Kenny]

In case the engine is ever realized and works as proposed - I can imagine there would be several military applications for an efficient Mach 1,5 (or so) supercruise off-the-shelf propulsion system.

Maybe? Most of the solid military supercruise applications seem to be either higher speeds (Blackbird) or need fighter performance.

Maybe a slower recon drone? I dunno.

Are they like the front-nozzle plenum burners for the BS100 engine designed for the aborted HS P.1154?

That is how I'm picturing it, yes. Just less weird/complicated plumbing upstream of them than needed to get the combustion happening in the corner in the BS100. Because there's no "corner" in the bypass ducts here.

Bjorn is correct in stating that compressor exit temperature T3 can be a limiting factor, just like turbine rotor inlet temperature T4.1, low rotor speed N1, and high rotor speed N2.

The response of the engine control system when reaching one of these limits is to stop increasing core fuel flow, or reduce fuel flow as necessary to keep at or below the limit. This reduces the aerodynamic rotor speed of the engine, reducing airflow, pressure ratio, and thrust. In supersonic flight, increasing inlet temperature with greater speed causes all these parameters to increase until one of them hits its limit (called the Theta break), with increasing inlet temperature causing loss of engine performance beyond that point. The total propulsion system performance can continue to increase with inlet ram recovery multiplying the engine pressure ratio for greater nozzle pressure ratio, but the engine contribution decreases beyond that limit condition.

Probably the very best example of this is the Blackbird, where at Mach 3 the engine was said to be dragging on the mounts (producing negative net thrust!) and the inlet and afterburner+ejector were making all the thrust to drive the plane at cruise.

 

[NMaude]

and the inlet and afterburner+ejector were making all the thrust to drive the plane at cruise.

That's why the J-58 is referred to as a turbo-ramjet.