Airfix 1/144 L.1011 w/Pegasus

  The Pegasus is an air-launched rocket developed by Orbital ATK, formerly Orbital Sciences Corporation. Capable of carrying small payloads of up to 443 kilograms (977 lb) into low Earth orbit, Pegasus first flew in 1990 and remains active as of 2016. The vehicle consists of three solid propellant stages and an optional monopropellant fourth stage. Pegasus is released from its carrier aircraft at approximately 40,000 ft (12,000 m), and its first stage has wings and a tail to provide lift and attitude control while in the atmosphere.

In a Pegasus launch, the carrier aircraft takes off from a runway with support and checkout facilities. Such locations have included Kennedy Space Center / Cape Canaveral Air Force Station, Florida; Vandenberg Air Force Base and Dryden Flight Research Center, California; Wallops Flight Facility, Virginia; Kwajalein Range in the Pacific Ocean, and the Canary Islands in the Atlantic. Orbital offers launches from Alcantara, Brazil, but no known customers have performed any. The capabilities of Alcantara are superfluous to other sites, without being any more convenient.

Upon reaching a predetermined staging time, location, and velocity vector the aircraft releases the Pegasus. After five seconds of free-fall, the first stage ignites and the vehicle pitches up. The 45-degree delta wing (of carbon composite construction and double-wedge airfoil) aids pitch-up and provides some lift. The tail fins provide steering for first-stage flight, as the Orion 50S motor does not have a thrust-vectoring nozzle.

Approximately 1 minute and 17 seconds later, the Orion 50S motor burns out. The vehicle is at over 200,000 feet (61 km) in altitude and hypersonic speed. The first stage falls away, taking the wing and tail surfaces, and the second stage ignites. The Orion 50 burns for approximately 1 minute and 18 seconds. Attitude control is by thrust vectoring the Orion 50 motor around two axes, pitch and yaw; roll control is provided by nitrogen thrusters on the third stage.

Midway through second-stage flight, the launcher has reached a near-vacuum altitude. The fairing splits and falls away, uncovering the payload and third stage. Upon burnout of the second-stage motor, the stack coasts until reaching a suitable point in its trajectory, depending on mission. Then the Orion 50 is discarded, and the third stage's Orion 38 motor ignites. It too has a thrust-vectoring nozzle, assisted by the nitrogen thrusters for roll. After approximately 64 seconds, the third stage burns out.

A fourth stage is sometimes added for a higher altitude, finer altitude accuracy, or more complex maneuvers. The HAPS (Hydrazine Auxiliary Propulsion System) is powered by three restartable, monopropellant hydrazine thrusters. As with dual launches, the HAPS cuts into the fixed volume available for payload. In at least one instance, the spacecraft was built around the HAPS.

Guidance is via a 32-bit computer and an IMU. A GPS receiver gives additional information. Due to the air launch and wing lift, the first-stage flight algorithm is custom-designed. The second- and third-stage trajectories are ballistic, and their guidance is derived from a Space Shuttle algorithm.

So far, there have been 45 launches. 38 were a total success, two a partial success, and three were failures.

The L-1011 is a kit that I got on the 'junk kit' table several years ago. I bought it specifically for this project and while it had been started, it was allegedly complete. Well the alleged engine fans were missing and finding a set of replacements turned out to be an impossible task. Forward a decade or so and a Revell A.320 kit provided a spare set of fans that, though a bit too small, did fit into the engine nacelles so the project was back on. For those not familiar with the Airfix kit, this is one with several sections of clear windows to put into the fuselage and all the various doors and baggage compartment hatches are separate.

The Pegasus was produced by Cutting Edge. It is a simple kt consisting of only seven parts. Two are the mount for the underside of the L.1011 and the rest are for the missile itself. No decals are provided, but Cutting Edge did a sheet for this which was duly purchased. The Pegasus is dated 2003 while the decals are 2004 so these are early in the Pegasus historyAll the C.E. bits are dated

As mentioned, the L.1011 was a kit that was already started. The previous owner had glued together the fuselage without installing the cabin windows or the blanking plate for the middle engine. He had also attached all the doors and the aft nozzle. Most of the fuselage seams had been filled, but needed a few more runs. He had also glued together the wings and tailplanes.

After sitting for many years, when I'd finally gotten something to use for the missing intake fans, I got back into the project. The fans fit neatly inside the mount frames and I closed up the engine nacelles. I also added more filler to the fuselage, took care of the nacelle seams and put filler on all the gaps of the flight surfaces.

Meanwhile, I constructed the Pegasus. While the molding on this is fairly good, I found a lot of errant resin lumps on some parts. This was a particular problem with the wings where the entire trailing edge was imbedded in a resin sludge. Cutting the wings from the sprue and then sanding the trailing edge was time consuming. The wing also does not fit well into the upper fuselage housing for it. This would not be an issue as it would be hidden by the pylon mount. The tail fins have no guide as to placement and anyway, the upper one will eventually need to be drastically trimmed when attached, unless I wanted to cut a slot in the L.1011's lower fuselage for it. One thing I did notice when test fitting is that the alignment slot in the pylon is too far back and it won't allow the Pegasus to fit all the way forward. Some trimming of the attachment area on the Pegasus should cure that. 

Once the fuselage had been sanded down, I glued on the Pegasus pylon and blast area. These fit fairly well. I sanded down all the areas on the wings and tail planes that needed it. These all needed filler. It was then to start some painting. Little did I realize how much time this would take.

So, overall white. How hard can that be? Well, first thing I did was to spray on some white primer. This did nothing to cover all the filler so I sprayed on some grey. All sorts of glitches popped up out of nowhere and those had to be dealt with. Once that was done I grabbed some Tamiya gloss white in a spray can figuring that would help speed up the painting. Man, was I wrong about that. Each time I painted the fuselage, I had runs. After about four tries at this, I figured it was not working the best so after the fourth sanding, I simply used X-1 in my airbrush and took care of those issues. When cured, the area around the fuselage intake was masked and the lip was painted with Alclad II's polished aluminum.

As for the wings and the tailplanes, these were sanded to remove the more egregious seams and then primered with grey. This shade works well for the inner coroguard surfaces so I simply (if masking huge wings can be called simple) masked these areas and painted those areas with a light grey that was mixed. I did this with the horizontal stabs and the engine pylons. With those done, I use various Alclad II metal shades for the engine exhaust as well as the leading edge of the intakes.

With most of the painting done, I decided to apply decals. For this build, I used a set of Cutting Edge markings, sheet 44005. These have several options for the L.1011 and for the Pegasus. One of the L.1011 options was similar to the current livery (the sheet was produced in 2004). Unfortunately, this livery did not go as far as the Pegasus itself as it only had the older scheme.

Decals worked without any real issues. The sheet states these are for the Minicraft L.1011 or any other. Well, perhaps. They do not fit the Airfix kit perfectly. This is most obvious in the area at the top of the wing and in the rear. Apparently other kits have a large diamond shaped area around the horizontal stabs that the Airfix kit does not have, so the long stripe simply ends. The sheet also does not include cockpit window decals or any of the other door decals. Not having a dedicated set of markings for these areas, I had to mask the poorly fitting cockpit windows and leave the areas around the doors blank.

Eventually, all the markings were applied. I then cleaned up and painted the landing gear struts, wheels, and the gear doors. The wheel wells were painted aluminum. It was then a simple matter of attaching the landing gear and doors. Fit here is nice and tight for the main gear, but the nose gear is a bit wobbly until the cement dries.

Let me back up a bit regarding the Pegasus attachment. You see, the launch rail is such that the nose is pretty far back when left as it is. The fix for this is to trim the vertical portions of the rail as it is too long, hitting the wing well before the rocket is far enough forward. The vertical fin also needs to be trimmed to fit, or one can cut a slot in the lower fuselage for it. I did the trimming part and it took a bit of trim, test fit, repeat to get it in place.

I then attached the engines to the wings, glued the wings and tailplanes in place, and removed the masking from the cockpit windows. The final step was to attach a small piece of red stripe to the outside of the engine nacelles. Those who want to simplify painting the engines can do them in all bare metal as there are plenty of photos that show this configuration.

CONClUSTIONS

Finally, a project I've wanted to do for many years is complete. It was stalled for a long time because my kit was missing engine fans. While the smaller ones I used are not correct, they do fit to some extent and were all I needed in terms of motivation. The decals are best used for one of the very early configurations when the system was still in test, assuming one can actually locate them and the Cutting Edge Pegasus. It takes up a goodly amount of shelf space, but I am glad I decided to go ahead and do the project.

https://en.wikipedia.org/wiki/Pegasus_(rocket)

14 April 2017

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