Aerospike engine first test flight

[GregLocock]

World's first aerospike rocket test mid-flight successful

In a feat that can only be described as legendary, and after many months and a catastrophic setback, Polaris Spaceplanes has finally accomplished something that's never been done before: lit the fuse of an aerospike rocket in flight.

newatlas.com

Great fun.

Different company uses AI to optimise its design

AI-designed, monolithic aerospike engine successfully hot-fired

Showing how far AI engineering has come, a new aerospike engine burning oxygen and kerosene capable of 1,100 lb (5,000 N) of thrust has successfully been hot-fired for 11 seconds. It was designed from front to back using an advanced Large Computational Engineering Model.

newatlas.com

 

[TugboatEng]

Something is off here. That orange flame color doesn't look good. Previous tests achieved an acceleration of 9mph/s. That's an odd combination of units. Is that an acceleration rate of 0.0025 miles/s²? Is that even within the ability of their instruments to measure? I would be jumping ship as an investor with those results.

 

[MintJulep]

Mph/s is a traditional railroad unit for acceleration.

9 mph/s = about 13 ft/s² or 1/3 g.

 

[rb1957]

ok, so why would an aerospike research paper use a railroad term ? if you're using acceleration "g" is a good unit (and bi-lingual ... metric and imperial)

 

[3DDave]

"Polaris reported an acceleration of 4 m/s² " which appears to be from the makers.

The conversion appears to have been done by NewAtlas (possibly using ChatGPT?)

Considering that a convenient English/Imperial measure is miles per hour for spacecraft, (I think low Earth orbital tangential velocity is 17,000 mph, it would be easier on American readers to figure out how long it would take to reach that velocity in the way it is presented, though still a bit odd as this is on a test bed airplane and one has to back-track to determine the thrust based on the aircraft mass. Rocket scientists would not care about the acceleration of the test bed if the thrust value and specific impulse was available.

The report from https://europeanspaceflight.com/polaris-spaceplanes-complete-first-in-flight-rocket-engine-ignition/ does not include this conversion.

 

[GregLocock]

Maybe they only had velocity as an output so if in 3 seconds the speed increased by 27 mph the acceleration was 9 mph/s. We mix the time units on cars as well 0-60 mph in 7 s is 9 mph/s

 

[WKTaylor]

A 3-second test burn of a new engine in flight is kinda like...?

 

[btrueblood]

I'm not sure what the hoo-hah is about either Wil, Cal State Long Beach launched the first aerospike test rocket back in 2003? Air light of an engine is not that big a deal, though perhaps shut down and re-light might be interesting for a suicide-burn lander like the spacex booster...and a bit less so for an aircraft.

From what I saw reviewing work at Rocketdyne some 30 years or more ago - the biggest issue is getting coolant fluid down to the narrowest point of the aerospike, along with sufficient cooland to the throat area (highest heat flux zone) whilst keeping the overall weight of the engine reasonable for a given thrust. They concluded while it's possible to build an aerospike, the performance benefit (higher thrust at low altitude) doesn't overcome the weight penalty.