Convair NX2 CAMAL Nuclear Bomber

blackkite said:
Hi! Convair model 54. The title of this drawing is tactical airplane!? Perhaps the engine was not a final design.
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'Tactical' comes up quite a lot in US aircraft documents of the era. It's used to differentiate the 'tactical airplane' which is designed for combat missions from a prototype or research aircraft - the fact that a particular aircraft might be used for a strategic mission doesn't affect that.

Although having said that, I think it's clear that none of the engines was truly a final design!
blackkite said:
Hi! I feel that Convair model 54 is not NX-2.
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With loosely defined parameters, it's equally possible they're different stages in the same design cycle.
 
This drawing is also mysterious for me. This design had 6 chemical jet engine and 4 nuclear jet engine!!
 

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That's one of those weird things I've just realized about ANP. That it would have needed chemical jets to go supersonic ! o_Oo_Oo_Oo_O
 
Archibald said:
That's one of those weird things I've just realized about ANP. That it would have needed chemical jets to go supersonic ! o_Oo_Oo_Oo_O
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Nothing to do with going supersonic, I think - this is a development (i.e. experimental) aircraft, so presumably needed sufficient conventional power to get from the airfield to a suitable test area and back again. The aircraft shown just isn't going to be capable of more than nominal supersonic performance.

I imagine that 'NX2' is an abbreviated form of 'Nuclear Experimental 2', strongly suggesting a development pipeline something like:
  1. The NB-36H carries out in-flight reactor safety experiments as was historically done.
  2. A modified B-36 (the X-6) or B-52 flight tests an operational nuclear jet engine on a well-understood aircraft capable of handling the weight.
  3. The NX2, or something like it, is built to demonstrate a nuclear-powered aircraft capable of flying a representative mission. This would likely have sufficient chemical power for flight with the nuclear engines totally shut down for safety reasons, hence the multiple engines on the 'Development Airplane'.
  4. Based on experience with the NX2, an operational aircraft is produced.
Obviously, all involved would expect that the development aircraft would form the basis of the initial operational aircraft, so the two would need to be developed in parallel. I expect a cutaway of the 'Development Airplane' would show the space given over to test equipment and additional takeoff/climb fuel was the same as that used for armament on the 'Tactical Airplane'.

Both drawings seem to be an early stage of design before the integral single reactor/single engine configuration was selected for the XNJ140E, but surely still from the General Electric side of the project: note the identification of 'G.E. Control Package' on the 'Tactical Airplane'. Also, whilst no conventional engines are carried, there's 73,000lbs of fuel in wing tanks - the XNJ140E was capable of operating in a chemical mode for takeoff and landing.

The program summary report on OSTI linked upthread (and here for anyone who doesn't fancy looking for it) is fairly clear, by the way, that 'Model 54' was a generic Convair aircraft configuration and 'NX2' a particular iteration of that configuration to achieve the CAMAL mission. The report is well worth a close read if you're interested in the project.
 
Okaaaay... I've just done some extensive research on the NX-2 powerplant: and found a crapton of documents.
Let's start from the simplest one, that cleared a lot of confusion for me.

Fasten your seat belts...

Pratt = CANEL = indirect cycle = NJ-18A = JTN-11 = a nuclear JT-11 = a nuclear J58 = for the Convair NX-2.

Undestood ?

So the Convair NX-2 was to fly on J58 power, just like (at some point or another) the SR-71 extended family (d'uh) but also: the Seamaster, and the F8U-3.

The attached document is a Godsend. It makes clear that NJ-18A = 4 * J58s with a liquid metal reactor.
 

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And the whole lot. Basically: what Pratt (= CANEL) did with the indirect cycle, post 1961 ANP cancellation (besides the SNAP-50 spaceborne reactor, but that's another story)

For the record: Convair NX-2 was to fly with 4 nuclear J58s grouped in a package called the NJ-18A propulsion system.
 

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Archibald said:
Okaaaay... I've just done some extensive research on the NX-2 powerplant: and found a crapton of documents.
Let's start from the simplest one, that cleared a lot of confusion for me.

Fasten your seat belts...

Pratt = CANEL = indirect cycle = NJ-18A = JTN-11 = a nuclear JT-11 = a nuclear J58 = for the Convair NX-2.

Undestood ?

So the Convair NX-2 was to fly on J58 power, just like (at some point or another) the SR-71 extended family (d'uh) but also: the Seamaster, and the F8U-3.

The attached document is a Godsend. It makes clear that NJ-18A = 4 * J58s with a liquid metal reactor.
Click to expand...
Man, I do NOT like liquid metal reactors, especially molten sodium types. They make the heat exchangers complicated beyond belief.
 
Sure let's take a highly reactive metal, melt it and then pump it around while keeping it in a molten state. Easy peasy. Oh, yeah we're also going to put it in an airplane.
Those documents are awfully sanguine about developing solutions to the issues concerning materials able to withstand molten sodium salts being pumped around at 90psi.
 
jcf said:
Sure let's take a highly reactive metal, melt it and then pump it around while keeping it in a molten state. Easy peasy. Oh, yeah we're also going to put it in an airplane.
Those documents are awfully sanguine about developing solutions to the issues concerning materials able to withstand molten sodium salts being pumped around at 90psi.
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Yup, that's why the Navy yanked the sodium-cooled reactor out of the Seawolf SSN575 and dropped in a normal PWR in the first overhaul.

They had a devil of a time keeping the sodium out of the steam generators!
 
Scott Kenny said:
Man, I do NOT like liquid metal reactors, especially molten sodium types. They make the heat exchangers complicated beyond belief.
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Unfortunately, the only real alternative for nuclear jet engines is open-cycle air cooling. Steam doesn't get hot enough to do the job.

On the plus side, there aren't any steam generators for the sodium to get into... you just get radioactive molten sodium leaking into the atmosphere instead. Once it's been through the turbine stage, probably radioactive sodium vapour. Sounds fun.
 
How about a Molten Salt Reactor ? Oak Ridge was on the case, 1956-57: with the ART, Fireball and a few other concepts. Is MSR compatible with indirect cycle NAP ?
 
I’ve just ordered a copy of this;-https://www.amazon.co.uk/Atom-Plane-Young-Lieutenant-Development/dp/1720779724

Looks interesting;- anyone else read it?
 
The whole premise is interesting. Certainly it faced much more planning than previous ventures. Even if the wings were rated for 40,000 hours, the premise sounds awfully shaky as you would need to have a steady supply of wings. Your time in the hanger would be much longer due to having to recertify every tangible component. Imagine how much lubricant you would go through in a few days, let alone a week. And your windscreen would not enjoy much care, so I can imagine seeing through the front glass could get tricky at some point.
 
Yellow Palace said:
Unfortunately, the only real alternative for nuclear jet engines is open-cycle air cooling. Steam doesn't get hot enough to do the job.
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Depends on how much pressure you run the system at. Supercritical boilers are a thing, where the water is above 374degC/705degF and pressures over 22.1MPa/3200psi.

Plus you can use a combined cycle with a steam turbine in addition to the heated air to drive the compressor.
 

Two reports I'd really, really like to read...

NJ-18A power package: ground test program, 1961-1965

NJ-18A power package: flight test program, 1963-1967

Green, R.S. "Development Plan for NJ-18A Power Package Flight Test Program, 1963-1967".

CNLM-3317. Pratt and Whitney Aircraft, Connecticut Advanced Nuclear Engineering Lab.,
Middletown, CT. Jan. 24, 1961 (Decl. June 12, 1976). 34p.

The Pratt & Whitney Aircraft plan for the flight test portion of the engineering and development of
an indirect cycle nuclear propulsion system capable of satisfying the requirements of the Convair
NX2 airplane is presented. The planning covers the power package scheduling and costing
involved in: (1) a flight test-bed program devoted primarily to propulsion system development and
(2) a nuclear powered aircraft development program devoted primarily to the resolution of
practical nuclear aircraft operation. These two major programs of flight testing will be conducted
in two NX2 aircraft. The program plans, schedules, and cost estimates presented are contingent
upon a continuing program from 1960 through 1965 with funds, additional facilities, and new
facilities being made available as required.
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Scott Kenny said:
Depends on how much pressure you run the system at. Supercritical boilers are a thing, where the water is above 374degC/705degF and pressures over 22.1MPa/3200psi.

Plus you can use a combined cycle with a steam turbine in addition to the heated air to drive the compressor.
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I thought Convair was turning fuel into plasma via exposure to radioactive isotopes, not producing electrical power per se. I thought the plan was more along the lines of a pulsejet while subsonic then transitioning to hybrid ramjet at and above transonic speeds. You can use ram-air turbine (RAT) generators for electrical at that point.
 
MadRat said:
I thought Convair was turning fuel into plasma via exposure to radioactive isotopes, not producing electrical power per se. I thought the plan was more along the lines of a pulsejet while subsonic then transitioning to hybrid ramjet at and above transonic speeds. You can use ram-air turbine (RAT) generators for electrical at that point.
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No, just simply heating the air using a reactor instead of via combustion of fuel.

Trident said:
That's probably weight-prohibitive though.
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Yeah, 3200+psi makes for some thick pipes.
 
Archibald said:
WS-125A lasted only 1955-1956 before supersonic flight proved unachievable. Hence the subsonic CAMAL was pitched instead.
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That's something I didn't know. I honestly thought that WS-125 started out as a nuclear-cruise/chemical-dash design; then evolved into a design that would be capable of continuous supersonic speed.
 
CaseyKnight said:
That's something I didn't know. I honestly thought that WS-125 started out as a nuclear-cruise/chemical-dash design; then evolved into a design that would be capable of continuous supersonic speed.
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To be honest, it's hard to be sure. The ANP program seems to have been a huge mess. The indirect cycle went from solid core to molten salt to liquid metal reactors.
My (limited) understanding was than circa 1956-57 they found a supersonic nuclear aircraft was impossible (don't ask me why - a matter of power density ?)
 
shockonlip said:
Sorry for the delay, finally found it!

I include a photo of the cover page, and the 5 photos of the vehicles.
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The black thing in front of the aircraft carrier's 'island'... What is it? A shield?
 
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Archibald said:
To be honest, it's hard to be sure. The ANP program seems to have been a huge mess. The indirect cycle went from solid core to molten salt to liquid metal reactors.
My (limited) understanding was than circa 1956-57 they found a supersonic nuclear aircraft was impossible (don't ask me why - a matter of power density ?)
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It's possible that they couldn't dump enough heat out of the reactor and into the jets.

Hound Dog missiles were supersonic without afterburner, but were also running at the ragged edge of staying together. Anything else supersonic needed afterburners to dump enough heat/energy into the jet to make enough thrust.
 
publiusr said:
How might this be modified to fly in a gas-giant as a probe?
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Only modifications would be to materials not chewed up by the gas giant's atmosphere at the planned flight altitude. Stuff that won't care about being super hot while surrounded by hydrogen.
 

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