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Jess Sponable: Project History & Management Lessons From DC-X, X-40, and XS-1

Never met an air force officer who would listen when I told them they need to learn how to manage. All had their own ideas how to manage things.

(That last was paraphrasing, as it will be until further notice)

Work part time for Aerospace corporation, but speaking for myself.

If you want to have access to the solar system, you'd better have reusable launch vehicles, reusable transfer vehicles, and reusable landers. Only way to bring costs down dramatically, only way to bring reliability up. Not everyone will agree but this is my opinion based on my experience. (Ed: And he has a lot)

Long USAF hypersonics history. Lesson: reusable aircraf-like access to space is not a new idea.

Venture capitalists shy away from reusables because they don't have the billions. Doesn't take billions, it takes a smart design.

Many rocketplanes, 1960-2000. Lesson: vertical takeoff & landing is simpler & easier to do.

Lot of bias toward horizontal take-off & landing. It can work, but VTOL is a lot easier to do.

National aero-space plane program. Lesson: $3B spent between 1986 and 1994 - biases can be expensive. Active cooling, complex airframe integration, need a lot more total delta-V because of drag. Low propellant density because LH2 is 4.4lbm/ft^3 - grows the aiframe. Active cooling of the surface over 40% of the surface area. (Ed: this was a challenge with the SR-71 & Valkyrie as well).

HAVE REGION rocketplanes in the 1980s. Lesson: USAF bias was vertical takeoff & horizontal landing. Used rocket sleds to get off the ground. Used SSMEs & a 1970s structure, with titanium, superalloys, and a few composites. Integral tanks: Mechanical, pressure, thermal loads.

Rocketplane metallic structures were fabricated. Lesson: successfully tested, albeit durability concerns persisted. (From the slide)

Fast forward to 2019: SpaceX approach, BFR Steel-300 airframe with active cooling.

NASP program was developing advanced composites, but there are some thermal advantages to metallics. Can SpaceX find a balance point to fly with something heavy like steel and make it work?

Why in the world isn't the US government out in front and trying to put these cutting edge technology in the pockets of entrepreneurs?

Slide: Single stage rocket technology studies, circa 1991. Lesson: two-stage or not to stage - both can work with pros & cons.

Still like aerospike rockets (ed: efficient at a much wider range of altitudes, attractive for SSTO), but they have issues.

Single stage costs a lot more, smaller payloads, but current commercial market has small payloads right now.

Recurring cost projections from the 80s & 90s. Lesson: consitent projection of flight costs below $300/lb & $3M/flight.

HAVE REGION in the 90s built & tested SSTO structures, SSTO project built DC-X in 90s.

Airbreathing - high Isp but with challenges. (went through slide very fast)

High Isp essential for hypersonic cruise, but NOT space access.

DC-X "ops lab" - flight tested from 1993-1996. Lesson: cheaper, faster, better possible, but hard for government contracing.

DC-X/XA demonstrated:
* Streamlined management
* Aircraft-like O&M
Total ops team was 25-35 people
Small crews of 6-12 people
* Aircraft-like flight ops
- Excellent crosswind & adverse weather landing capability
NASP & HAVE REGION matured lightweight structures in parallel
Todays commercial marketplace traces its heritage to DC-X (bottom text cut off)

DC-X was a complete system, more than a vehicles. Lesson: infrastructure need not cost billions

Vertical take off and landing. Lesson: many key advantages.

In my opinion, it's a much better solution.

Key advantages:
* Incremental flight tests
* Powered landing
* Few facilities
* Minimal real estate
* Adverse weather flight
* Flexible abort envelopes
* Minimal dry weight & development cost
* Altitude compensating nozzle option

DOD technology & flight tests paved the way. NASA "x-planes" in the 90s, the "billionaires" in the 2000s. Many hypersonic children.

Many space access concepts studied. Lesson: Two stage or not to stage? Rocket or airbreathing?

Slide shows RAM & SCRAM concepts along with rocket concepts. Most of the rocket concepts are two stage and thus much smaller.

What has changed? Rocket plane technology readiness level is high - TRL 6+.

Past programs over-spec'd requirements (SSTO, scramjets, heavy lift, crewed, etc) and used immature technologies.

XSP demonstrated 10 flight duration engine ground tests in 10 days.

We're up to the point where the private sector has jumped in and a lot of people are chasing launch systems.

Can't argue with the success Elon has had. Designed for full reusability from the get-go. My concern with Blue Origin & SpaceX is that they've sucked up a lot of the energy of the VC & entrepreneurial world, and I'm convinced you can do this with a lot less money.

DARPA: What is Phantom Express? Reusable hypersonic first stage, expendable upper stage

Goals: Fly 10x in 10 days, no upper stage/payload

Key technologies. Lesson: Composite structures and ceramic TPS are mature. Large scale structures, Complex structures, Polyimides, panel structures.

Shtructure weight: shuttle era vs now, we're 30-50% lighter now.

Composite cryogenic tanks are mature. (Pronounced "Big Falcon Rocket" in a way that was almost indistinguishable from "Big Fuckin' Rocket"), called Starship now.

Optimized composite solutions must be designed in. Lower cost - higher for design but lower net. Why? Affordable comopsites. Smart design - 10x fewer parts.


Pump fed rockets once the province of BIG government. Not anymore. Lots of big rockets, >100k lbf thrust, and little rockets, 5-35k lbf thrust.

Hypersonic airbreathing & rocket technologies overlap - a lot!

If I had my druthers I'd like to see a program that pushes component technologies and makes them available to industry, just like <something> in the '60s.

Predicting the future disclaimer. Lesson: beware of the "experts". Lots of examples of "experts" being wrong about where the technolgiies will go. "Man will not fly for 50 years" in ~1900.

Maturing now: reusable first stage. Mach 4-12 reusable first stage enables access to space & global reach.

Coming soon: fully reusable space access. Enables global reach aircraft. SR-71 CONOPS offers analogy for fully reusable global reach CONOPS. Survivable in A2/AD environment. Hard to kill with once around missions. Deploy/reconstitute when & where needed. Deters use of ASATs against US sats.

Starship is an example of fully reusable. Akin to deltaclipper circa 1996 only much bigger. Resolves key issues: simple cylindrical shape is easy to build. Fins/canards for yaw control, high alpha flight, etc.

Aircraft-like fully reusable access to space, which is where Elon wants to go. Point-to-point transport. Payload is huge. 747 sized.

Significant overlap between military & commercial needs.

What will be the cost of a ticket to space?

Ticket price to orbit $101. (bunch of text in the middle of the slide eaten by keynote) "Assuming we can work out a few engineering details.

Flight rate critical. Cost still 100x the cost of electricity (what he used to compute the ticket price to space at extremely high rates). There is room for improvement!

Aircraft-like ops enables military spaceplane(s) and global-reach aircraft.

(Ed: I only care about this because it's a way to get government to fund research_

Boost glide P2P transport is a leapfrog approach. Got a 7,000 mile range, almost global reach. Not going all the way to orbit, never going to zero G. 50% of people get sick. Out-of-shape guys like me actually do better in zero-g.

Giant slide fully of "a few key lessons". Not going through the whole list, just a summary of previous slides so already mostly written up.

Management lessons learned. (Full transcription of slide)
* Agree to clearly defined program objectives in advance
* Single manager under one agency
* Small government and contractor program offices
* Build competitive hardware, not paper
* Focus on key demonstrations, not everything
* Streamlined documentation and reviews
* Contractor integrates and tests prototype
* Develop minimum realistic funding profiles
* Track cost/schedule in realtime
* Mutual trust essential

So often get into this situation where government and the contractor are adversaries. Bad, bad mistake.

A few lessons from DC-X
* Fast track, rapid prototyping can be done by govt, but it's not easy
* Precise vertical landing possible, differential GPS allows landing on launch stand
* Blended differential throttling with engine gimballing, elimination of all hydraulic gimbals should be next goal?
* Engine out abort during flight, potential for aircraft-like reliability
* VTOL can land on cement, grated trench, unprepared and "prepared" gypsum.
* Hydrogen insidious, leaks, but can be managed safely

* Employed Matrix X to autonomously generate flight software at ~10x lower cost
* Low cost, minimal and transportable infrastructure designed for both ground and flight test

BIG DC-X lesson learned: Government start/stop investments damage the industry. Be consistent.

Build X-Planes, not systems
Take incremental steps
Build on successes (don't keep starting over from scratch)

Federated Republic of Sean @freakazoid

Final thought: just do it!

From October 9th, 1903 edition of the NYT: "flying machine might be evolved by the combined and continuous efforts of mathematicians for 1 million to ten million years."

SAME DAY, from the journal of one of the Wrights: "We have started assembly."

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Question about oxidizers & composites.

A: LOX can cause fires, but there are ways to use it safely. Some interesting storable propellants that might provide an alternative to LOX.

Question from Dave Weinshenker about reusables vs just trying to drive manufacturing costs down. "Tin can like" vs "aircraft like".

A: Room for both, reusable is better for reliability.