Mach 2 1/72 X-24B Lifting Body.
|NOTES:||The only injection molded kit of this unique aircraft|
Research done on ballistic missile nose cones found that blunt shaped objects were able to resist aerodynamic heating associated with atmospheric re-entry. NASA’s predecessor NACA found that by modifying a nose cone aerodynamic lift could be achieved and a spacecraft could conceivably fly back from space rather than rely on a ballistic trajectory.
In order to explore this theory NASA developed the M2-F1 which was basically a half round nose cone shape with the flat side up and twin fins at the rear. This vehicle was an un-powered glider. Known to its pilots as the flying bathtub the M2-F1 began life being towed behind a
There were three heavier, rocket powered lifting bodies that followed the M2-F1, the M2-F2, the HL-10, and the X-24. The X-24B was the last of the lifting bodies to participate in the program and was actually a redesign of the X-24A. After the successful completion of the X-24A flights the Air Force ordered the X-24 airframe returned to Martin to be modified so it could test new lifting body shapes. This was considered to be a cost saving measure. The new shape was intended to test vehicles with higher lift to drag ratios.
The original X-24 was a short and pudgy aircraft with two outer fins and a center fin. After its modification the X-24B emerged as a flying flat iron. When the arguably ugly X-24A emerged as the X-24B it was sleek triangular craft that would have looked right at home in a science fiction film.
The X-24B had its first flight in 1973 and flew until 1975. In that time the X-24B reached a top speed of Mach 1.75 and twice was able to make a glide landing right onto the main runway at Edwards. This was a program milestone and proved that unpowered reentry was possible.
There were plans to build an X-24C that would combine the lessons of the lifting bodies program with those of the X-15 program. A study was completed by Lockheed for an airframe known as L-301. The vehicle was to be power by a rocket engine which would have accelerate the craft to hypersonic speeds and then propulsion would have switched to a SCRAM jet ultimately attaining a cruising speed of Mach 6. There is some conjecture that this vehicle flew in 1982.
The Mach 2 X-24 is a dual kit of the X-24A and X-24B. I will be addressing the assembly of the X-24A in a later review but for this section the comments will be common to both reviews. When you open the thin box you are greeted by a single grey sprue that is bagged. Rolling around loose in the bag are four injection molded canopies. Ideally you should only need two. At first glance I was pleasantly surprised by the quality of the parts but once I removed the sprue from its bag and had a closer look I could see there were some issues. There was a fair amount of flash and excess plastic where it shouldn’t be. One of the main gear wells for the X-24B was completely filled in with plastic and one of the two interior tubs was misshapen. The plastic feels soft and a little greasy and there are many ejector pin towers that need to be sanded, snipped or otherwise dealt with. The canopies are thick and cloudy and also suffer from flash. One of the four canopies had a chunk of plastic taken out of one side as if it had been roughly clipped from a sprue. The control panels are chunky and badly marred but once cleaned up they have ok detail for the scale. Smaller parts for the most part need clean up and many could do with being replaced with aftermarket or scratchbuilt items.
The instructions comprise a single sheet of paper that is supposed to suffice for the assembly of both aircraft. Suffice to say they are not detailed but the X-24 is not a really complex aircraft either so if you armed with reference photos you will find them almost adequate. There is a single small sheet of decals that contains decals for both kits. They are glossy and thick and the printing appears a little blurry to my eye. Unfortunately there are only two yellow NASA Tail flashes included when there should be four, one for the outer portion of both fins for the X-24A & B. NASA meatballs are not very well printed and neither are the Air Force Material Command shields that appear on the X-24B
Before actual assembly started I spent a lot of time removing parts from the single sprue and cleaning them up and figuring out if I could use them or if they required an alternate strategy.
I decided from the word go that I would treat this as a resin kit. Everything requires clean up and some modeling skills are required. Based on how soft the plastic was I decided to use super glue for assembly. I was afraid that a hot glue like Testors Plastic Cement would be too aggressive on the soft plastic. The X-24B was given preference in build order because it is my favorite of NASA’s lifting body aircraft. I cherry picked the best parts for the X-24B as many of the A & B parts are simply duplicates. This decision will come back to haunt me when I start on the X-24A but we will cross that bridge later.
I started with what I considered the most challenging aspects of this project, the port main gear well and the interior. After picking the better of the two interior tubs I started to cut and scrape the excess plastic from it. The tub is molded as a single piece and is badly marred by an ejector pin crater in the center of the floor and flash everywhere. I started at the flash with an x-acto blade and files and then tried to deal with the crater in the floor. The crater was ugly and deep. There was also a pile of plastic built up in one corner as well. I decided that the tub was only partially salvageable. So, I got out the razor saw and removed the fore and aft bulkheads. With those removed I was able to sand the cockpit floor until it was flat and to sand the walls until they were flush and square with the floor. I used the bulkheads I removed as templates to make replacements from styrene sheet and then tacked them in place with super glue.I scrounged some PE from a Hasegawa F-14 fret to use for the side consoles which were devoid of detail. I added some rib detail to the cockpit tub walls above the consoles from thin strip styrene. Then I selected a control panel from the sprue. There is one each for the x-24A & B and they are identical. I selected the better of the two and then cleaned it up painted it grey and picked out the details with dark grey and black. Once this was dry I installed it in the tub which I had already painted grey. Then I installed the tub in the upper fuselage half and set it aside to dry.
The X-24 used a Weber ejection seat and
the kit part bears little resemblance to the seat that was in the real aircraft.
My first plan was to just fudge it but after cleaning up the kit part to see
what I had to work with I decided that I would need to replace the seat with
something more convincing.
There are no X-24 ejection seats available from the
aftermarket folks. No surprise there.
the F-101 used a Weber seat and True details offers an aftermarket F-101 seat.
It is not 100% accurate but it looks a lot better than the kit part and has a
similar look to the X-24 seat. Conveniently you get two in a pack so I will have
one for both the X24A & B.
All that work left the interior in good shape. Not intricate but at least a little busier than what you get to start with. Next I attacked the plastic filled port main gear well. I had no illusions of saving this part so I grabbed some styrene sheet and used the starboard well as a master to make the port well from scratch. This went much quicker than I expected and in no time I had a passable facsimile of a landing gear well and when it was installed it looked the part just great.
Moving along nicely:
After all of this was accomplished I installed the gear wells in the lower fuselage and the interior tub in the upper fuselage half. The rear plate/engine mount was installed at this point as well. It fit poorly but that may be as much the fault of my aggressive anti-flash efforts as it is the kits. I should note that the plastic in the kit is rather soft and sanding and cutting should be done with caution.
Once the interior bits were dry I assembled the upper and lower fuselage halves and filled the seam along the leading edge of the fuselage. Things fit better than I expected they would and clean up was helped by the fact that the only real seams were around the leading and trailing edges of the lifting body.
With the fuselage together I glued on
the outer fins. These fit ok but required a bit of filling on the inboard seams
and at the point where the leading edges meet the fuselage. I then installed the
center fin. I think that this fin is off in how it sits but I can’t from the
pictures I have looked at and it was super glued in place so I will just live
At this point I took one of the canopies and sanded it to fit the canopy opening on the fuselage. Once it fit I sanded it down with progressive finer micro mesh sanding sticks and then hit it with a gloss coat and this greatly improved its clarity.
While the canopy was drying I built the XLR-11 rocket engine. It went together OK except that there is not enough room on the engine face for all four nozzles so I did the best I could. The nozzles were a real pain to clean up and I will most likely figure out a strategy for replacing them altogether when I build the X-24A. They also did not fit in the holes drilled on the mounting plate. The holes were drilled too close to each other. So, I did my best and got them on there in some kind of order. After that was together and drying, I added some detail that I had sanded off the fuselage rear plate and then added the outer flaps on the outside of the fins.
|COLORS & MARKINGS|
After doing some more filling and sanding of various problem areas I masked the canopy and secured in over the cockpit with silly putty and then shot the entire fuselage with Tamiya acrylic silver. I like to use silver as a primer for tough projects as it shows all of the flaws that I still need to fix.
After I had addressed the issues brought forth by the primer coat I was ready to start painting for real. There is a great photo in the NASA Dryden photo gallery of NASA research pilot Bill Dana in front of the X-24B after its final flight in 1975. Dana is wearing his infamous pink boots with yellow daisies and cream colored g-suit while he is interviewed by a local TV crew. The X-24B behind him is in overall white with a black anti-glare panel and sky blue leading edge. I decided to paint my X-24 as it appeared for this final flight.
First I sprayed a couple of coats of
white and then masked everything but the leading edges and then sprayed them
Tamyia sky blue. Once that was dry I unmasked and discovered that blue overspray
had still made it into the white so I masked the leading edges and re-sprayed
the white areas where they needed it.
Then I masked the black Anti-glare panel and painted
Once everything was dry I hit it with a coast of Testors Gloss Coat.
The kit decals were iffy so I went
ahead and purchased a set of decals from Don’s Model Works. They sell a
vacuformed model of the X-24 and they sell the decals separately. They are a
vast improvement over the kit decals and they layed down very nicely with a
little setting solution. I got two national insignia from the spaces box to
complete things and when everything was applied and set I sprayed a gloss coat
to seal everything in.
At this point I attached the engine and fuel dumps, landing gear, gear doors and rear fuselage flaps. Everything went together without much trouble. In truth the landing gear and fuel dumps should be replaced with better items but at this point in the project I was feeling a little spent and decided I could live with what was in the box after I had cleaned the parts up a bit.
My last task was to attach the nose probe which I replaced with brass wire and at that point I declared this project done.
This was a challenging kit despite having a fairly low parts count. However it did not present any challenges an average to slightly better than average modeler could not handle. Sure there was some scratch building involved but nothing too drastic just a wheel well and some interior bits. This would really be a good kit for someone who wanted to try stretching their skills a bit. In the end the builder will be rewarded for their efforts with a very unique and interesting model of a subject that is not likely to be kitted by more mainstream manufacturers.
NASA Dryden Fact Sheet – Lifting Bodies www.nasa.gov/centers/dryden/news/FactSheets/FS-011-DFRC.html
Marietta X-24B, Wikipedia
Lockheed L-301, Wikipedia http://en.wikipedia.org/wiki/Lockheed_L-301
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