Flying the
Aero Vodochody L-29
Delfin Jet Trainer...Flying the
Aero Vodochody L-29
Delfin Jet Trainer...
When I was about 4 years old, my father (who was 72 at that time) was pushing me down a San Francisco street in my perambulator. I remember looking up and seeing something bright and shiny in the window of a storefront we were passing; although I didn't know it at the time, the object in the window was a new US Air Force jet training aircraft known as the Lockheed T-33 Thunderbird. The year was 1950 and the US Air Force had only been a fully autonomous branch of the US uniformed services for just under 3 years.
Some years later I recognised that now familiar silver aircraft profile and learned from my mother that the window we had passed that day looked out on Market Street from the Air Force recruiter's San Francisco office. The recruiter had obtained a model of the T-33 (which had been built as a two-seat 'stretched' training version of the famous Lockheed P-80 Shooting Star) and was using it to draw attention from passers-by in the street, since in 1950 turbojet powered aircraft were still considered quite a novelty by the average citizen. That beautiful model certainly caught my childish eye and my encounter with it was the beginning of what for me became a life-long passion for aviation.
Regrettably, a chronic sinus problem ruled out
the pilot training program for me once I was old enough to consider taking
flight training, and at any rate the Vietnam War found my college grades just
coasting along at a 2.0 GPA, so I ended up enlisting in the Air Force to avoid
being forced to hunt NVA ducks in a Vietnam rice paddy. That association with
the world of military flight resulted in my ending up as an aeromedical
specialist, where I usually worked for the flight surgeon at the bases I was
stationed at. Since I was on flying status as unassigned aircrew in that
capacity, all I had to do was catch a certain number of hours of flight time
each month to keep that small flight pay stipend coming in. I usually logged my
time in relatively slow and stable multi-engined aircraft such as the KC-135,
but I occasionally caught back-seat rides in faster birds (one such thrill was
in a two-seat Convair F-106B model "Six"--part of Minot AFB's 5th
Fighter Interceptor Squadron in North Dakota, where I was stationed in 66 &
67).
Despite my Air Force flying opportunities, I never did make it up in the back-seat of a T-33 Thunderbird, although an unrequited childhood resolve had been to someday go for a flight in one. As was the norm at that time, although 5th FIS flew (at the time) advanced F-106 delta winged interceptors in their Air Defense Command duty at Minot (which was principally a SAC base), they also had a T-33 assigned to them which usually served as the squadron commander's 'hack'. Most ADC F-106 squadrons had one of these redoubtable old training birds in the squadron and they were frequently used for miscellaneous mundane duties in the squadron. Despite the splashy glamour and thunderous clamor of the F-106s on full afterburner, there was still something special and uniquely fascinating about the ubiquitous T-bird, with its slow-spooling, old fashioned axial-flow turbojet engine.
To this day (May of 2005) I still have not
fulfilled that youthful promise to get airborne in a T-bird, despite the fact
that there are a number of these old birds still flying. Last year I joined the
Commemorative Air Force (formerly 'Confederate Air Force' until that name fell
victim to 'political correctness') and became a 'Colonel' in the Golden Gate
Wing, after learning that that wing had restored MiG-15 UTI and T-33 warbirds.
I'm still trying to arrange a back-seat ride in GGW's T-bird, but so far 'no
joy'.
This spring I was planning to take a back-seat ride in one of Rick Svetkoff's restored two-seat Lockheed F-104D model Starfighters, since his Starfighter's Incorporated operation in Florida offers flights in that classic jet (he is currently having a TF-104G restored); as the McClellan Aviation Museum's B model Starfighter crew-chief, I was eagerly looking forward to being able to say I had actual flight time logged in an F-104. As events often turn out, however, we bought some property in Hawaii this spring to retire to, so that much anticipated $7000 thirty minute flight fell victim to our change of circumstances.
There I was, bemoaning my opportunity to go supersonic in a Starfighter, when one of my fellow McClellan Aviation Museum board members brought me a flyer promoting instructional flights in a former Soviet Bloc jet trainer. The aircraft in reference is an Aero Vedochody L-29 Delfin ("Dolphin"), a primary jet trainer manufactured in the 60s and early 70s in Czechoslovakia. An organisation called SOMA Aviation, operating out of Troutdale, Oregon, offers instructional flights in an L-29 they have restored. Amos "Scott" Malone and his wife Carena operate SOMA as a family endeavor and Scott is the owner, aircraft mechanic, and instructor pilot for lessons given in their L-29 Delfin. Scott flies the L-29 north and south along the Pacific Coast, from his home base in Troutdale, scheduling weekends at various municipal airports where individuals interested in taking 30 minute or 60 minute flights can receive varying levels of instructional orientation to the aircraft. Scott's wife and his two sons follow him on the ground to each site in a caravan mobile home and take care of the logistics, scheduling, and paperwork for each operation.
This sounded like a great opportunity to dust
off the flying boots and break out the bone-dome (without simultaneously also
breaking the family 'bank'), so I scheduled a flight with
Scott at the Placerville Municipal Airport, located in California's historic
'Gold Rush' country in the Sierra Nevada foothills. The flight took place a week
after I had returned from a month in Molokai (HI), which was in fact just two
weeks ago.
The story behind the Aero Vedochody L-29
Delfin is an interesting one and it is worth observing that the L-29 is a
fairly contemporaneous Eastern Bloc nations counterpart to the West's Lockheed
T-33 Thunderbird. As the inheritor of much of WWII Germany's advanced aviation
technology, Czechoslovakia was in an excellent position to play a leading role
in the development of Soviet aeronautical
designs at war's end, since the USSR
had taken over that nation as another of its Socialist Republic 'Cold War'
satellite nations. Thus it was that in the late 50s, Aero Vedochody advanced a
design for a two-seat training aircraft using the new turbojet engine. This
tandem trainer (two man cockpit, each airman seated fore and aft, instead of
side-by-side) designated the XL-29 prototype first flew in April of 1959, using
a single British provided Bristol Siddeley Viper axial flow turbojet engine
offering about 1500 pounds of static thrust. A second Delfin prototype
using a Czech developed single Motorlet M-701 1-stage centrifugal (axial) flow
turbojet flew in July of 1960, followed by a pre-production prototype that was
placed into competition for a standardised Soviet jet trainer which it won. The
L-29 (which was Czechoslovakia's very first jet aircraft design) entered
standard production in early 1963. Production of the L-29 Delfin continued
for more than 11 years, the last airframe coming off assembly lines in 1974,after
more than 3600 aircraft of the type had been completed during that period.
Code-named 'MAYA" under the NATO Soviet naming nomenclature, the Delfin
served extensively in all Soviet Bloc and Warsaw Pact nations. Other foreign
nations taking delivery of the L-29 included the GDR, Romania, Syria, Iraq,
Bulgaria, Egypt, Indonesia, Nigeria, Uganda, and Hungary. Of the more than 3000 
L-29s built, it is estimated that today there are well over 50 of them still
flying and the L-29 has enjoyed a resurgence in recent years as a very popular
'warbird' in the United States and elsewhere.
With a straight-wing design optimised for sub-sonic flight, the L-29 features a high "T-tail" horizontal stabiliser and is intended for a maximum speed of about 0.75 Mach (about 0.7 Mach with tanks and underwing stores). Twin air intakes are built in, one on either side of the fuselage, that join together to feed the single engine's inlet. Built with sturdy landing gear that enabled operation from rough, poorly maintained fields, the Delfin is stressed to a maximum of +8 and -4 Gs and is therefore quite capable of aerobatics. The final production Czech designed & built M-701 turbojet featured a single stage centrifugal flow compressor with a 7 combustion chamber arrangement that is characteristic of early generational post-war jet engine technology; it is capable of producing about 1950 pounds of static thrust with a maximum operating RPM rating of about 15,300 (100%) and does not have an afterburner section. One of the most positive characteristics of the engine, despite its early axial flow heritage, is its solid and dependable construction (about 500 hours of operation time before major overhaul is required). It has proven to be extremely reliable in operational service and is fairly easy and simple to maintain without complicated tools and service procedures. These factors have contributed greatly to its popularity as a favorite modern 'warbird' among classic aircraft restorers and warbird enthusiasts today. In fact, at this time there are still about 5 foreign (viz. non-US) nations that use the L-29 Delfin for many military flying roles.
The fuselage comprises three distinct sections
that are joined to each other. The first is the nose section, followed by the
pressurised cockpit section, and the after engine section. The wing is a
single-spar, self-supporting metal skinned design capable of supporting twin
tip-tanks and underwing fuel tanks. The cockpit features an unusual canopy
design in that the forward canopy glazing opens like a clamshell to the right
(in a manner identical to that of the F-104 Starfighter), while the rear
canopy glazing slides aft to open. Inside the "office" are twin KK-1
type ejection seats that in normal operation fire in sequence (aft 
first,
followed by forward position). In most warbird restored L-29 Delfins the
KK-1 seats have been 'neutered' (rendered incapable of firing with pyrotechnics
removed), however, since operation with 'live' E-seats required extensive
servicing and FAA certifications ($$$!). As a result of the this, emergency
egress consists of manual bail-out that comprises three steps: 1) Canopy is
released into windstream; 2) seat-belt restraint is unlatched (pull device on
left side of belt latch) ; 3) aircraft is inverted by rolling and you simply fall free of it
(chutes use conventional manual D-ring pull). All of this assumes that you have
sufficient altitude with which to carry through the process, of course. If you
are too low and slow to bail, you grit your teeth, hang on, and ride the bird in
(a few "Hail Marys" wouldn't hurt at this point...).
Critics of the L-29 have described it as being
"too conservative" or "too simple", with its straight wing,
engine-root intakes and T-tail, and some have criticised the fact that the aft
cockpit has only been elevated 15 cm (6 inches) from the fuselage, giving the
instructor pilot (the student rides forward) a somewhat less than optimal view.
Others have criticised the Delfin as being slightly underpowered, with a low
power-to-weight ratio, modest performance, and being not very attractive looking. All
that having been said, such criticism is almost completely irrelevant, since the
aircraft was designed as a stable, student-pilot friendly, docile-handling,
uncomplicated trainer and it certainly succeeded in its intended design
parameters quite
admirably. With wide-track tricycle landing gear enabling rough field ops and
notable lack of any 'nasty tricks' lurking up its exhaust cone, the L-29 was a
perfect introductory aircraft for inexperienced student pilots. In fact, 
the L-29 was so simple and 'friendly' that more often than not, the Delfin
was a Warsaw Pact student pilot's very FIRST introduction to flight (there were
no initial propeller-driven trainers used
initially, prior to jet training, as is
the norm in the West). It has been noted that after about 13 hours of
dual-flight instruction in the type, with no prior flight training, a student could
solo the Delfin.
Reflecting on the reference to the Delfin not being very good looking, I have to take exception with that aesthetically blue-nosed opinion, since it is a design that grows on you subtly, the more familiarity you have with it. While my initial reaction to its appearance was not especially noteworthy, the more I examine it from all aspects, the more I like it. The only truly awkward element of its visual presentation in its somewhat unspectacularly designed engine tail-cone exhaust outlet; aside from that, I really think it's a rather nice appearing aircraft, myself (see three-view illustration of planform). The L-29 is as long as it is wide (with a span and length of about 35.5 feet), and stands 10 feet high at the tip of its vertical stabiliser. Empty weight is about 5000 pounds, while a full load of fuel and aircrew brings that weight up to about 8000 pounds at take-off. With its pressurised cockpit, maximum altitude is 36,100 feet, and maximum speed is generally in the range of about 407 mph. With fuselage fuel only, range is about 397 miles; with auxiliary tip-tanks, operational radius is about 277 miles (overall range = 555 miles, or about 2 hours of flight at optimal cruise). Despite its aerobatic capabilities, fully inverted flight operation is limited to less than a minute due to fuel feed limitations.
A former Czech Air Force Pilot informs us the L-29 was nicknamed
"The Pushcart"--an allusion to its docile,
slightly underpowered nature. A frequent Czech Air Force joke had it 
that the
only reason the L-29 Delfin could eventually get off the ground was because the Earth
is curved (a fully loaded normal take-off run from brake-release to rotation is about 1800
to 2000 feet, although a "high & hot" take off roll could require
as much as 3000 feet).
According to many who are very familiar with the L-29 Delfin's flight performance capabilities, the L-29 is actually a delight to fly. Just enough thrust and speed to keep a man satisfied, with aerobatic performance that can still induce a strong gagging sensation in the low-jet-hours crowd. Compared to the MiG-15 UTi's many dangerous handling characteristics, the L-29 Delfin is almost gentlemanly in its mild mannered requirements for correct pilot inputs (so I am told).
As for my own flight with Instructor Pilot Scott, it was a very pleasant experience. Scott was originally a rotary-wing pilot who subsequently took his fixed wing ticket and advanced in type to IP rating in the L-29. He acquired the L-29 after it had been refurbished to meet FAA minimum specs and this is reflected in its western labeled critical flight instruments, radios, etc. A typical flight lasts about 35 minutes and you operate at about 10,000 feet, hence no need for oxygen masks; ground/air and interphone communication is carried out with boom mics attached to Scott's HGU-55/P type flight helmets. You may use your own personal equipment with suitable connectors and amplifiers (if, for example, you are using low-Ohm military equipment with the A/C's high-Ohm civilian radios), but it is probably easier to just use Scott's gear. Scott provides you with a freshly packed standard back-style, conventional D-ring manually activated parachute, and I have already alluded to standard egress drill earlier in this article.
I arrived early at Placerville Airport
(altitude about 4000 feet) and watched a few of the students ahead of me take
their flights. On these instructional flights, the student flies in the front
seat (with a tremendous view, given the one-piece clear forward canopy glazing)
and the IP aft. There is a ground school lasting 2 hours the night before the
scheduled flight and the Aero Vodochody L-29 Delfin flight manual (known
to pilots as the Dash-1) is available at Scott's website to review any aspect of
flight operation, including emergency procedures, beforehand. It was interesting
chatting with some of the others who were there waiting for their rides. One of
these individuals was of Czech ancestry, who had his father with him. The father
remembers L-29s flying regularly near his Prague home, many years ago.
Refueling takes about 15 minutes between hops
(fuel consumption at cruise is about 190 gallons an hour) and the nitrogen pressure reservoir is also topped off at that time (for
gas-actuated systems aboard), with Scott doing his own refueling and between
flight servicing. Then you are ready to board the aircraft after strapping on
your chute. Once seated in the forward cockpit, which is small, but not too
cramped, Scott gives you a preflight instruction, usually consisting of
emergency procedures and engine-start operations (these are carried out from the
forward seat position). The engine start button is located aft of the throttle
at its base, so the student flips the appropriate battery, generator, at al
switches on command, then reaches over to the left and presses the engine start. The
engine then starts spooling up, after which a final check of instruments and
indicators is carried out, and you are ready to head out on the taxiway to the main runway.
Due to the peculiar characteristics of the nose-wheel steering system, a straight-line taxi is not a feature of the Delfin, and one zigs and zags gently
down the strip to the active runway (turns are accomplished using the brakes).
One final spool-up of the engine for a performance check after clearance to roll
and you're off. Acceleration is undramatic and there is none of that
kick-in-the-butt slam that an afterburner produces, but after about 
2000 feet of
runway has been used (up to 3000 feet on a very warm day--high & hot), you
rotate and begin the climb-out. Since Placerville's runway terminates at the
edge of a cliff (more or less!), there's a dip right after rotation that is
caused by some loss of ground effect lift and the ground-observer's view of the
maneuver is quite startling, since the plane seems to zoom down a bit out of
sight before
reappearing in a climb. Meanwhile you are increasing airspeed and climb out at
no more than about 1500 feet or so per minute. The day I flew, the clouds were
coming in and rain was on the way. Ceiling was about 11,000 feet and so we
operated at about 10,000 feet (THAT'S the norm for no-supplemental 02 flight
anyway), which was fine.
Since I'm not a rated pilot and have less than a few hours of actual stick-time in all types of aircraft, this was really just a joy-ride for me, but Scott let me fly the plane most of the time we were in cruise mode. Scott's instructional abilities are commendable and his manner and affect in that role are impeccable. With his proctoring and tutoring, I was applying my sparse USAF T-41C (military type fuel injected Cessna 172) light aircraft flight knowledge to the L-29 and found that the aircraft was a real easy and agreeable bird to handle. Turns, banks, altitude changes, and station keeping were all accomplished with no sweat and a relatively light touch on the stick--even for a novice like myself, who is more accustomed to rubber-necking in the aft crew position as pure 'lookie-looey' dead weight. Since I have a recurrent middle-ear & sinus problem that aerobatics do some unhappy things to exacerbate, I dared attempt only a single 360 degree aileron roll before calling it quits and sticking to more gentle maneuvering, prior to heading back to base. With a GPS system in the aft cockpit, Scott deftly navigated us back to begin base leg at Placerville, despite the presence of some light cloud formations and rain, and before long we were on final. Placerville has a nice little visual glide-slope indicator on the port side of the runway, so it was simply a matter of keeping the correct color light in view to descend properly, and very shortly, with proper throttle management, we flared the Delfin and gently kissed the runway at about 110 mph. Using about 4000 feet of runway to slow ourselves before turning onto the adjacent taxiway, we rolled back to the ramp and popped the canopies to let in some of that cool, crisp, and fresh Sierra mountain air. It was a very satisfying moment to say the least.
I had neglected to bring my log-book with me,
so I didn't get my 35 minutes of L-29 flight recorded properly, but what the
hell. In retrospect, I was well pleased with the whole operation. Can't say
enough good things about Scott and his instructor capabilities; he's always
right there in the cockpit with you, giving very helpful, calm, and informative
inputs, and he strikes me as one hell of a good man as well as a great IP. It
was truly a pleasure to fly under his competent and extremely good-natured 
aegis. I'd unhesitatingly recommend Scott and his SOMA Aviation L-29 jet
trainer to anyone who enjoys aviation and wants a positive introduction to jet flight experience. One further
comment: Scott uses a Mini-DV cassette videocam to record your flight and gives
you the tape when your flight ends (the camera is mounted on the forward
ejection seat's headrest, facing forward). It's a nice souvenir of your 35 minutes
flying a 'Dolphin'.
I've included a few helpful resources and URLs following this article for those who might wish to try flying a Delfin. There are several operations currently offering instructional flight training in the L-29 Delfin across the US (as well as several who offer similar experiences in the L-29's replacement, the Aero Vodochody L-39 Albatros, which is a more modern and somewhat more high-performance jet trainer). Although the L-29 is not the 'balls-to-the-wall' kick in the pants that a flight in an F-104 Starfighter or F-106 Delta Dart is, it is still a pure and immensely enjoyable flight experience for anyone who is aviation-minded. And, after all is said and done, flying ANY military jet aircraft is still the most fun you can have with your clothes on......
Blue skies and smooth air, Doc Boink (June 2005)
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(For more on the Aero Vodochody jet trainer
experience try the following:)
www.jetflights.org/ (SOMA Aviation L-29 Delfin flight instruction) Or call (503) 661-3266.
www.ruscoinc.com/jetstar/ JetStar International: operators of an L-29 Delfin.
www.globalsecurity.org/military/world/europe/l-29.htm Much technical information about the L-29.
www.airwar.ru/enc/attack/l29.html Everything you could possibly want to know about the L-29, but all in Russian!
www.jetwarbird.com/training.html/ Jet warbird training flights (T-33, L-29, L-39, Magister, you name it!)
(photo credits: 1) (Unknown); 2) Bill Shull; 3) Unknown; 4) Unknown; 5) Chris Carey; 6) Chris Carey; 7) Chris Carey; 8) Chris Carey; 9) Irene Kwan; 10) Unknown)