Came across a ram/scramjet review paper from the Stanford Center for Turbulence Research & it is an absolute treasure trove of wonderful illustrations related to hypersonics

A quick thread of my favorites, but first I got distracted w this simulation of scramjet combustion
Here’s a closer look at that animation, with links to the paper and YouTube source

What you’re seeing is an overlay of temperature, density gradient (analogous to schlieren), and velocity in a scramjet cavity at Mach 6.5

🎥
📄 web.stanford.edu/group/ctr/ResB…
So back to the review paper, a bunch of these figures caught my attention

First up since we’re already on scramjets, a great illustration of a combined-cycle turboramjet + dual-mode scramjet

Gets you from takeoff to Mach 10!

📄 annualreviews.org/doi/abs/10.114…
A schematic of the HIFiRE-2 scramjet configuration with lots of great technical specs/details
Similarly, this is the HyShot-2 cavity
On a more fundamental level, this is a great overview of the engineering/physics challenges related to hypersonic flight for air-breathing propulsion systems
A related summary for tactical boost-glide systems—notice the similarities? And the differences?
Last but certainly not least, this is an excellent figure highlighting the differences in flight profiles and trajectories of a variety of systems, from cruise missiles to ballistics to traditional LEO rocket launches

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More from @DrChrisCombs

2 Apr
NASA just released some interesting preliminary data from their instrumentation onboard the #Mars2020 lander that delivered #Perseverance

Here’s a quick thread w some thoughts

[TLDR: Mars entry is HOT, but we made the heat shield too big (again)]

So to start, let’s turn back the clock to 2012. While you were watching The Walking Dead and the London Olympics, the good folks at NASA were measuring the aerothermal environment of Mars entry for the Mars Science Laboratory (MSL Curiosity) mission
They did this with an instrumentation suite called “MEDLI” which stands for Mars Entry, Descent, & Landing Instrumentation

This contained, among other things, a bunch of heat transfer, pressure, and temperature measurement devices in and around the MSL heat shield
Read 13 tweets
20 Feb
Oh my goodness, this is video of the turbofan on a Boeing 777-200–flight #UA328 out of Denver—which experienced a serious engine failure after take-off.

Remarkably sounds like no injuries in the air or on the ground #AvGeek
I mean, just look at these photos...
#AvGeek #ua328
Worth noting, twin-engine aircraft are designed to be able to fly safely with only one engine and pilots are trained for this (seems they did a phenomenal job here!)...but people and homes are NOT designed to withstand falling turbofan cowlings. Miraculous no one was hurt
Read 12 tweets
19 Feb
WOOWWWWW

Check out these images of #PerseveranceRover being dropped from the sky crane (left) and descent with chutes deployed via Mars Reconnaissance Orbiter! Incredible photos!

#Mars2020 #Perseverance #NASAPerseverance #NASA #Mars ImageImage
Folks, we just snapped of a photo of a spacecraft landing (possibly still at supersonic speed) on ANOTHER PLANET from a satellite also orbiting that planet. That is WILD

#NASAPerseverance #NASA #PerseveranceRover #Perseverance #Mars2020 #ScienceTwitter Image
I just can’t believe this image—am I right that we’re seeing some of the dust plume from the retro rockets? This is like a baroque painting Image
Read 5 tweets
18 Feb
NASA is LIVE with coverage of the Perseverance landing, happening around 2:55p US CT, this is the place to be

Percy about to hit the atmosphere at 3.5 miles/sec (5.5 km/s) and create some serious heat
#CountdownToMars #MarsPerseverance #Perseverance

pscp.tv/w/cv11hDFsWkVw…
The extreme velocity of atmospheric entry will heat the surface of the heat shield to nearly 2,400 F (1,300 C) due to intense shock heating and aerodynamic forces
It’s a tricky part of the mission for many reasons, but our ability to predict/model the physics of these atmospheric entry events is currently limited—it’s a “multi-physics” problem which makes it tough even for our best super-computers to handle
Read 5 tweets
23 Nov 20
It’s November which means we’re getting into GRAD SCHOOL APPLICATION SEASON so I thought I’d take a break from my usually #AvGeek/rocket threads & talk some #AcademicChatter with my personal advice for those considering grad school. A thread...

#AcademicTwitter @AcademicChatter
All the usual caveats apply: I’m in engineering and while there are many different paths & perspectives I’ll be giving advice based on my personal experience. With that said hopefully it’s helpful to many of you w/ broad applicability outside of engineering
First: don’t pay to go to grad school. Many faculty have paid research assistantships (GRAs) and will provide tuition + stipend. You’ll still be underpaid but it’s really difficult to economically justify the benefit of grad school vs lost income if you pay your own way
Read 33 tweets
1 Sep 20
THIS IS NOT A SONIC BOOM

Okay folks, it’s been long enough. Time to finally address the biggest point of confusion on #AvGeek twitter: what exactly is going on with vapor cones?

Let’s just say much of what you’ve read is (probably) wrong. Wonder no more: a thread... 1/n
2/n We’ve all seen the photos & videos—whether it’s a jet flying over the beach or a rocket during its ascent—with the beautiful vapor cone (you also hear shock collar or even shock egg). Inevitably the exclamations follow: “sonic boom!” “Mach 1” & “breaking the sound barrier”
3/n And I totally understand. It’s a nuanced concept & a quick Google search brings up all kinds of misinformation. I could not find a single article that seemed to truly “get it”. So no shaming here—it’s debunking time
Read 25 tweets

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