One of the few good uses for solid rocket motors

[GIThruster]

You don't get a 62% reduction in range from adding a copilot.

Just like you don't store fuel in the fuselage.

[GIThruster]

How about this...

AI upset recovery... how cool!

The aircraft on display at The Air Force Museum (S/N 58-0787) was involved in an unusual incident. During a training mission from Malmstrom AFB on February 2, 1970, it suddenly (NOT ALL THAT SUDDEN!) entered an uncontrollable flat spin forcing the pilot to eject. Unpiloted, the aircraft recovered on its own, apparently due to the balance and configuration changes, caused by the ejection, and miraculously made a gentle belly landing in a snow-covered field near Big Sandy, Montana. After minor repairs, the aircraft was returned to service. It last served with the 49th Fighter Interceptor Squadron before being brought to the Museum in August 1986.

Sure this wasn't an episode from Outer Limits or some such? ". . .and miraculously made a gentle belly landing in a snow-covered field. . ."?!!!

That's just so hard to believe. No flaps? Landing without wheels at 300 MPH? Twilight Zone. . .anyone remember the short lived follow-on that featured the glider pilot who was murdered by a jealous lover, was launched and flew away, then returned and landed years later after WWII? Was totally creepy.

[93143]

More details on the incident here, at the bottom of the page. The plane was evidently in takeoff trim as part of the pilot's failed recovery effort.

Incidentally, that site lists a 1950-mile range (1695 nm) with tanks. No conditions, as usual...

This site says 1500 miles. And this site says 1700 miles range, which coincidentally is ~2700 kilometres, and matches the number for the B variant given here...

Where are people getting these numbers? Okay, the 1809-mile ferry range at least appeared in a (web transcript of a) book...

Regardless, with a 1500-1800-mile range, prejudice towards the low end due to higher speed on an intercept mission, lop off a bunch for high-intensity combat maneuvers, and cut the result in half - 575 miles sounds reasonable.

Apparently the navigation maps displayed to the pilot covered a 400-mile radius from the operations base - not that this proves anything...

I might try to calculate the range myself. There appears to be enough information available...

You don't get a 62% reduction in range from adding a copilot.

Just like you don't store fuel in the fuselage.

You don't store all of it in the fuselage. You're talking about over half the fuel load being removed to make room for one guy. Drag wouldn't explain it; the shape wasn't all that different - in fact, it turned out the area ruling was actually better with the larger/raised cockpit... The TF-102A had aerodynamic problems, but that's because the pilot and copilot were seated side by side, a mistake that was not repeated with the F-106B...

This web page gives considerable detail on the fuel tankage arrangement (there's a typo; it says 40 gallons in the fuel lines when it should say 30. Also, when they list total capacity including drop tanks, they apparently mean the 230-gallon subsonic drop tanks. The numbers match up fairly well with known fuel weights, assuming JP-4 at 6.5 lbs/gallon). Apparently the B variant lost about 110 gallons of capacity from behind the cockpit (out of 1514 gallons total internal fuel), which was partially offset by larger wing tanks. There was another 40-gallon tank listed as "behind the pilot", which may or may not have been removed. Total fuel capacity of the F-106B was 32 gallons less than that of the F-106A.

So no, you don't get a 62% reduction in range from adding a copilot.

Coincidentally, that website also shows the same range numbers as this one, in a similarly-arranged table to boot...

[jsbiff]

Once they had the Mach 3 Blackbird flying, the downside of ultra high speed set in. Word has it that it takes three states to turn the SR-71 around at that speed, and the states are Texas, Alaska, and Hawaii. Dogfighting becomes moot at those speeds.

I thought the point of high speeds was A) the ability to get to an 'interception point' faster, and B) to make it so the enemy can't out-run you?

What I mean with A) is that, if your radar detects bombers flying over the Pacific (or N. Pole) from the USSR, it's better to engage them ASAP, before they can get any farther - I mean, when you scramble the jets, they are going to have some time to keep coming, but if you have fast jets, you can set a flight plan to burn at mach 3, then start decellerating down to 'engagement speed' as you near the point where you will meet the enemy, no?

You would probably try to get *behind* them as they are flying towards canada, then accellerate as quickly as possible to be in a position behind them where you can shoot at them (where you are both going mach 1.5 or mach 2, whatever, but relative to each other, there's hardly a speed difference)?

[93143]

Well, I guess you can only go so fast before it starts harming other performance metrics. Weight, cost, maneuverability at combat speed... also, the time required to accelerate to max speed means you start getting less benefit for non-extreme ranges, particularly if your aircraft is heavy or aerodynamically suboptimal at lower speeds.

The mission profile you describe requires reasonable maneuverability. If you overshoot a supersonic bomber, it's not easy to catch it again. Also, back in the '60s, over-the-horizon backscatter radar hadn't been developed yet...

The CF-105 (just to pick an example at random) would have required significant modifications to dash at Mach 3, and cruising above Mach 3 like the Blackbird was right out (except for the titanium-skinned concept version with variable intakes and quad ramjets under the wings, which probably wouldn't have ever been built...). However, it was designed to sustain Mach 1.5 in a 2 gee turn at 50,000 ft without losing altitude. It was a relaxed-stability design with fly-by-wire and electronic stabilization, with (customizable) artificial feel. It had very low wing loading (lower than the F-106), was stressed to (according to an interview with the chief test pilot) 7.6 gees, and had a combat T/W of about 1:1. The Blackbird would have been a laughable opponent in a turning fight.

There's probably a reason they designed it to be so maneuverable...

[TallDave]

I wish you rocket scientists could stop puttering around with chemicals and tin cans and just build me a damned nuclear-driven space-carrier already.

I can't believe NASA stole the Orion name for their crappy little CEV. Now I have to disambiguate, jerks.

[GW Johnson]

Ah! A fan of the old USAF "Orion"!

So am I.

[krenshala]

Its definitely annoying when people say "Project Orion" but mean "Orion capsule". When i first heard someone talk about NASA working on Orion I asked if they meant Project Orion, and then had to explain to them what I was talking about.

[93143]

The old Orion idea was great. A few practical issues, mostly political - though the EMP might have been nasty on modern satellites... I attempted a BotE thermal analysis of the 4000-ton reference design a while back on this very board (in response to someone who was claiming it would overheat), and it came out looking quite comfortable. Naturally enough; it's not the sort of thing I'd expect an effort on the scale of Project Orion to overlook...

[TallDave]

I say screw the test ban treaty.

Aren't there trajectories where EMP isn't an issue?

I'd love for China to announce tomorrow they're doing it. Once the interplanetary genie's out of the bottle...

[GW Johnson]

The old "Orion" was a funded USAF program, based on earlier company-funded work at General Atomics in San Diego. USAF funded exploratory paper-design R&D 1959-1965.

The team flew a one-meter model on HE pulses, even though they were not supposed to experiment. There were some debris observations from the atomic tests in Nevada that confirmed the acceptor plate would survive long use just fine.

Their baseline design was a 10,000 ton "interplanetary ship" about 185 feet in diameter and 280 feet long. Its design mission was a 3 year round trip to Saturn and back, stopping off at the moon and Mars along the way, all as one single stage.

Ship empty weight was 3250 tons, and it was constructed of stout stuff like 1-inch steel plate, not the thin aluminum beer can stuff we have been flying. The rest is propulsive charges and payload. Total mission delta-vee was around 100 km/sec, and the design acceleration level was 2-4 gees. This ship was intended to launch from Earth's surface. You realize, of course, this is ca. 1960.

"Orion" died ca. 1965 when USAF was divested of its space programs, which were turned over to NASA. NASA saw "Orion" as a competitor to its Project "Rover" nuclear thermal rocket efforts, instead of the complement that it truly was. So, NASA failed to fund any real "Orion" work, and it died.

The nuke rockets, BTW, were "baseline" for the manned Mars mission planned for 1983. By the time Apollo was killed in 1972, the Mars mission had been pushed back to 1987. It wasn't just Apollo that got killed: Nixon killed all human flight out of Earth orbit. So, in its infinite wisdom, NASA killed its nuke rocket program: "After all, why build the rocket if we're not going to go?"

The last nuke rocket test was in 1973: the solid core design called NERVA. The Timberwind and Dumbo designs were even better, but never got tested. There was an even better gas-core variant under study. The first test article was planned for about 1974 or 1975, but never got done. For Mars or the NEO's, you could use either a nuke rocket or the "Orion"-style pulse propulsion. To go further, you need "Orion".

The "Orion" pulse design is very peculiar: efficiency increases as you scale up the size of the vehicle. Isp's around 6000-10,000 sec at 10,000 tons look more like 12,000-20,000 sec at 20,000 tons. The design of the pulse-spreading acceptor plate and tuned-shock system gets easier at higher ship masses, too.

That's all based on 1950's fission explosive technology. It could be updated to a 10-times-more-efficient thermonuclear technology, I think, rather easily.

Those explosives weren't much good as weapons, either. They had a "propellant" mass as part of the package. And, these were shaped-charge highly-directional devices, not omni-directional blast devices. Each detonation produced a collimated spike of plasma from the "propellant" mass, so that the acceptor plate intercepted all of it, not just a tiny solid-angle fraction.

Yep, EMP might be a problem, but probably not quite the same way as a weapon. I suspect it might be quite the directional pulse, along the plasma jet axis. Or at least most of it. (BTW, the ancient 1950's vacuum-tube electronics are intrinsically hard against at least some EMP.

Quite the interesting beast. I cannot think of a better place to test such powerful stuff than the airless, waterless, neighbor-free moon.

[Aero]

The "Orion" pulse design is very peculiar: efficiency increases as you scale up the size of the vehicle. Isp's around 6000-10,000 sec at 10,000 tons look more like 12,000-20,000 sec at 20,000 tons. The design of the pulse-spreading acceptor plate and tuned-shock system gets easier at higher ship masses, too.

Doesn't that mean that the final mass of your spaceship doesn't really matter very much with regard to acceleration capability? Or does the larger Orion spaceship use larger propulsion units? In either case, you could add on options with a lot of flexibility and mass tolerance.

[TallDave]

Yep.

http://en.wikipedia.org/wiki/Project_Or ... ropulsion)

In fact, they looked at 8M ton ships as a real possibility. That's about 100x the size of the largest naval supercarriers. You could probably send one as a self-sufficient colony ship to a nearby star, once we find some habitable planets.

We should really have at least one around in the thousand-ton range for asteroid-protection duty. Just common sense, really.

[kunkmiester]

Modern nukes are quite efficient at reasonable yields--a 400 kiloton device can burn upwards of 90% of the plutonium, while this drops radically for a 10 kiloton device. For a larger ship, you use larger "propulsion modules" and the weight of the "propellant" that isn't burned to produce energy goes way down. So, hundreds of thousands of tons for ship was more practical than a few hundred or a thousand or so for a Saturn V or Nova size ship.

This also gives the advantages Johnson mentioned--with such favorable mass fractions, the weight penalty of over-engineering stuff is not worth worrying about, so you build it like a tank, as mentioned, and have fun. What's more, this isn't something you drop into the atmosphere after use--you'd build a heavy lifter so you can refuel and resupply, then you're off to Neptune or wherever after the Saturn trip. After a while you launch an upgraded ship, and how you have two--eventually the older ones are sold off to private enterprises that use them for asteroid mining or whatever.

[GIThruster]

So, hundreds of thousands of tons for ship was more practical than a few hundred or a thousand or so for a Saturn V or Nova size ship.

Perhaps but you would never build out of inch thick plate steel. The re-radiation you'd get inside the ship would kill everyone. The last thing you want is a steel spaceship.

Now 5" of wet filament wound carbon fiber composite with it's higher water content would work really well, but y'all do know we're talking about a $100 billion program. Stuff of dreams but no one is ever going to build such a thing.