In the mid-60s, West Germany developed a program that would allow its F-104 Starfighters to
take off just like this:
This was the ZELL program, short for Zero Length Launch,
that was developed together with Lockheed and basically attached a rocket
booster to the F-104G that was mounted on a launch platform.
In this video let’s talk about why Germany came up with the program, how they implemented
it and why this program was cancelled despite being successful.
The origins of the ZELL program date to the early 60s during the Cold War.
As you know, West Germany was the very first line of defence for NATO against the Warsaw
Pact and it was believed that if the Soviets were to attack NATO they would first use nuclear
weapons to destroy NATO’s air bases in Germany, thus crippling NATO’s air defence and blocking
NATO from setting up a counter-attack.
In light of this the new Luftwaffe wanted to reduce its vulnerability and dependability
on long runways and minimize its losses from aircraft destroyed on the ground if there
was a surprise attack from the communist nations.
One idea that the Germans had was to scatter fighter jets launched from mobile platforms
throughout the countryside, far away from the main military installations, and use them
for interceptions, conventional ground strikes or even nuclear strikes on counter-attack
missions if hostilities had started.
The platform of choice for this program was the F-104 Starfighter, in special the “G”
variant of the aircraft that comprised the bulk of the German air force and was used
as a fighter bomber.
As a matter of fact, when Germany was in the process of buying the Starfighters from Lockheed
they already had the ZELL program in mind together with another program called SATS
(Short Airfield for Tactical Support) which envisioned the F-104 taking off from catapults
on short runways and using an arrestor hook for landings which would even allow the Starfighter
to land on highways.
Flight testing for the ZELL program began in 1963 at Edwards Air Force base in California
and the early portion of the testing was done by Lockheed under a contract with the German
government which was the main operator of the Starfighters.
Before testing with manned aircraft, Lockheed first used some mock-ups made with concrete
and steel beams that had the same characteristics as F-104s in different weapons loadouts including:
weight, centre of gravity and momentum.
The launch of these mock-ups with a rocket booster had been successful so it didn’t
take long and Lockheed started flight testing with a specially modified version of a German F-104G.
Lockheed test pilot Edward Brown performed some successful launches with the aid of the
rocket booster at Edwards and given that all the launches had been successful the program
then moved to Germany in 1966.
In Germany, a fixed launch platform was built at the Lechfeld air base near Munich and further
demonstrations of the system took place in the summer of that year.
Other than Lockheed’s Edward Brown, the only other person to take off with the ZELL
F-104 was the German test pilot Horst Phillip who also did some of the demonstration of
the system in Germany.
I should also mention that despite the F-104’s bad safety record in the Luftwaffe which I
cover in another video, there were no accidents during the entire ZELL program.
However even though the system was successful in launching the Starfighters from a platform
with the aid of a rocket-booster that would allow Germany to scatter its forces along
the countryside and minimize their losses from a surprise attack from the countries
of the Warsaw Pact, the ZELL program was cancelled in October of 1966 after Germany had spent
over $25 million on the project.
But before we talk about why the program was cancelled let’s first take a look on the
specifics of how the launch system worked.
Attached to the rear lower fuselage of the F-104 was the North American Aviation Rocketdyne
solid rocket booster, the same rocket system designed for the TM-61 Matador nuclear cruise
missile from the 1950s.
The booster was attached to the plane at an angle of 20 degrees with a special mount,
had a diameter of 74 cm, a length of 4 metres and a weight of approximately 1,894kg and
could produce 120,000 pounds of thrust for a total time of approximately 8 seconds.
8 seconds may not sound like much but by the time of the burnout of the rocket booster
the aircraft was already 600 metres downrange from the launch station flying somewhere between
120 to 210 metres above the ground and with an airspeed between 250 to 350 knots – depending
on the take-off configuration of course.
After the burnout of the rocket the rocket mount would be jettisoned from the aircraft
either manually or automatically.
During the take-off sequence the pilot was always in control of the launch system.
After climbing on the launch platform which already pointed the aircraft up by 20 degrees,
the pilot would first apply full afterburner on the J79 engine and then press the ZELL
switch for the activation of the rocket booster.
Now although all the ZELL F-104s launches were done on a fixed launch platform, Germany
also had in mind the development of mobile launchers who would add more flexibility to
the Luftwaffe because one limitation of launching the Starfighter with the ZELL system was the
10 knots crosswind limit – but as I said this would be solved with the mobile launchers.
So now let’s get back to the topic, if all the ZELL launches were successful then why
was the program cancelled in 1966?
Let’s start with the minor issues which were the maintenance and operation of the system.
First it was difficult to install the rocket mount under the aircraft because of the special
modifications, in addition to that the Germans also needed to load or unload the aircraft
from the launcher and they also needed to boresight the rocket booster.
Another issue would be the security of the equipment because placing a Starfighter equipped
with a nuclear warhead in the middle of the countryside would also demand the creation
of a facility that was secure enough to accommodate both the aircraft and its nuclear armament.
Another limitation was the 10 knots crosswind component which although could be solved had
Germany developed a mobile launcher - it would only add to the complexity of the program.
Adding to the logistical aspect, you would still need to transport the Starfighter by
ground to the desired location of the launch site and then have it mounted to the launcher there.
Now for this other point let’s assume that the Warsaw Pact had indeed attacked NATO and
used nuclear strikes to destroy the airfields in Germany, which is exactly the scenario
the ZELL program was developed for, even if the ZELL Starfighter was able to takeoff for
either an interception or a nuclear counter-attack against the communist nations – how was
the aircraft supposed to come back if there were no air bases left especially with the
F-104's short range?
These points serve to illustrate why the ZELL program was, although possible, not practicable.
Yet even more important for the cancellation of the ZELL program, as well as the SATS program
that was being developed at the same time in cooperation between Germany and the US
Marines, was the strategic shift by NATO in 1966.
In that year NATO came up with a new Flexible Response strategy that shifted the focus from
the use of nuclear warheads to the use of conventional weapons if a conflict between
NATO and the Warsaw Pact was to occur.
This was the fundamental change in the assumption that the communist nations would use nuclear
warheads to destroy Germany’s infrastructure which was the very principle for the development
of the ZELL system.
The German Zero Length Launch program with the F-104 Starfighter was the last type of
ZELL program to take place and just like early American and Soviet tests from the 1950s with
the F-84s, F-100s and MiG-19s, it failed because it wasn't practicable even though it was possible.
However despite its cancellation and the money that went down the drain, there were
a few positive aspects that came from the German program.
First was the modernization of the German Starfighter fleet with the Martin-Baker GQ
7A ejection seat that had been featured in the ZELL program.
Now it was said that during the critical phase of the ZELL launch even the new ejection seat
packed with additional rockets wouldn’t be able to save the pilot if something was
to go wrong, but fortunately there was never any accident during the ZELL program.
Now if you are really interested in the ZELL program you can still see the only F-104 in
the ZELL configuration at the entrance of the Luftwaffe museum in Berlin-Gatow if you
happen to be around the region.
And if you want to learn more about the ZELL program I’ve added all my sources in the
description including the books I used to make this video.
If you happen to buy them on the link provided you not you get the book but you also help
support the channel since I’m on Amazon’s affiliate program and this comes at no additional
cost for you.
But if you want to watch more videos on the F-104 you can check my previous video on why
the Luftwaffe had a bad safety record with the F-104 or you can watch this other video on the
rocket-powered Starfighter used for astronaut training in the United States.
Anyways, thank you for watching, hope you have enjoyed this video and see you next time!