[ExI] fun memories of rocket stuff from a long time ago

[Adrian Tymes]

On Tue, Sep 30, 2025 at 12:57 PM <spike at rainier66.com> wrote:
> Adrian, looks like you have done a lotta lotta work already.  I wasn't aware your concept was this far along.  This stage of development looks like something you could pitch to the generals and get funding from DARPA.

We are in fact trying to pitch to DARPA.  We keep running into "That's
a good idea, let me think about it..." and then utter radio silence,
not even replying to any follow-ups (next week, next month, half a
year later - nothing works).  Being silent, no reason for this silence
is made apparent (unless I happen to hear from other channels, which
usually aren't available).

> I do apologize, for I fear my fingers have written checks my fingers aren't ready to cash: I don't have the bandwidth to study this now, with medics tomorrow and Thursday, then a camping trip next week, and the overall drive of getting ready to take in an elderly father in law who might need our help soon.

If it takes you a few weeks or a month to get to it, no worries.  Let
it percolate in your brain until then - just so long as you do,
eventually, get to it.  (See above comment about indefinite silence.)

> There is commercial software my son was using that appears to be good enough for creating plausible ascent profiles.

We have a simulator for this case.  The point is to validate against
software that others have done, with their creators able to comment
whether it's more likely that their software is off or our estimations
are off.  Commercial software generally doesn't offer that feedback.

> Unless we have specific fuel use profiles, my spreadsheet won't really do much for us anyway: it is designed for chemical rockets and will only estimate drag better than the commercial products, but even then it isn't clear how far those have advanced since Robert Bradbury and I worked together more than a decade ago.

Define "specific fuel use profiles", but it might be in there?

> Also: your nuke rocket appears to be a partial (clarification pls?) air-breather

Not the model in the report.  Air breathing is a possible extension -
we have applied for (and not gotten funding for) funding to develop in
that direction - but this specific version is 100% self-contained.

> Regarding thrust to wt of 3: that in itself will not prevent you from achieving single-stage-to-orbit necessarily.  You will have greater gravity losses with the leisurely acceleration profile, but don't write off the idea based on that alone.

And we're not - not entirely, anyway.  But we'd prefer better.

> I might hafta stand down for now

Is that "for now" as in you might be able to get back to it in a
month, or "for now" as in "forever"?

> Fun aside: if working with a competitor is not out of the question: SpaceX funds edgy research like this

We've thought about that.  Two conclusions:

1) We have no way to get a message to him that he'll read.  He has
gatekeepers whose job is to keep folks like us from planting ideas in
his head.  Without a way to crack that, we have no way to engage with
SpaceX.  The only possible route seems to be to build it and
demonstrate - and pretty much count on Elon (and most of SpaceX) being
unable to know that we exist until that demonstration.

2) After we demonstrate, we could scale up on our own - but the
official Plan A is to offer to license to SpaceX (and Lockheed, et al)
so that, if they do hear of us before then, they don't try to
astroturf fake public outcry so as to try to shut this project down.
Better to be seen as an eventual ally than as an eventual threat.