The gliders of Pat Beatty and Fritz Johl (longish!)
Charles Crosby
I thought some people on this newsgroup might find it interesting.
-----------------------------------------------------------------------------
THE HOMEBUILT SAILPLANES OF PAT BEATTY
Charles Crosby
Although many homebuilders are also enthusiastic glider pilots, homebuilt
gliders are quite scarce. One possible reason for the lack of homebuilt
gliders is that very few have been truly competitive with the German
production models. There have been some notable exceptions, however; for a
period of nearly thirty years, several remarkable gliders were designed and
built in South Africa by Pat Beatty, at times assisted by designer Fritz
Johl. There can be no doubt that Pat's untimely death in a road accident
in 1991 robbed South African gliding of some more truly innovative designs.
The story starts a long time ago, however. Patrick James Beatty was born
in Pilgrim's Rest in 1920. Like many others of his time, he learnt about
aircraft and flying through models, which he flew with some success, at one
stage competing in the World Championship in the UK. He received his
Aeronautical Engineering Training at Cranfield in England, and served as an
Engineering Officer in the RAF during World War 2. He became involved in
gliding during his time at Cranfield. He returned to SA after the war, and
started Performance Sailplanes, with the idea to produce gliders locally.
A licence was obtained to manufacture the Grunau Baby. Unfortunately, the
hoped-for local market never materialised, and only one Baby was produced.
In order to survive, commercial wood-turning work became the main activity
of Performance Sailplanes.
The BJ-1
Soon after the Grunau Baby was completed, Pat Beatty and Fritz Johl teamed
up to design a world beating glider. The 'BJ-1' was designed in 1953, and
the designers were confident that it was going to be a world-beater. Like
all subsequent designs, the BJ- 1 was designed for South Africa's strong
thermals - it had a very high wing loading for its time, and was equipped
with trailing edge flaps to improve low speed flying.
The BJ-2
The BJ-1 was never completed. Soon after the construction process started,
the two designers came up with an even more radical design, the BJ-2. The
BJ-2 took the idea of a very high wing loading, combined with a flap for
low speed flying, to much greater extremes. The BJ-2's wing loading was
much higher than the BJ-1's already high value, and a very large
Fowler flap was added to get acceptable low speed characteristics. This
was one of the first gliders to use the now universal T-tail, and to add to
the glider's already distinctive nature, conventional airbrakes were
discarded in favour of two tail-mounted drag chutes. The decision to use a
high wing loading meant that there was nothing to be gained from building
the wing light. This allowed the use of a plywood wing skin 3/16" (4.5 mm)
thick, about three times the value then accepted as normal. The objective
was to realise the very low profile drag theoretically obtainable from the
NACA 65-418 airfoil, by making the wing skin smooth, stable and accurate
(and almost unbelievably heavy!). Construction of the BJ-2 took seven
years, in the garage of Pat's home in Edenvale. The glider was of all-wood
construction, with moulded spruce plywood wing skins and spruce spars. The
front of the fuselage was a plywood monocoque, and the fat (by today's
standards) tailboom consisted of a spruce truss structure, with plywood
skins. Tail surface construction was similar to the wing, and only the
rudder was fabric covered.
The BJ-2 flew for the first time in 1961. Incredibly, nearly all the
innovations worked, and Pat Beatty won the South African championships with
it in 1962. In the hands of Pat Beatty, Yvonne Leeman and 'Boet' Dommisse,
several world records were achieved, two of which stood untill the late
60's. In 1965 the BJ-2 was flown in the World Championships in England by
Boet Domisse. The venture was not a success. The weak British conditions
did not favour the heavily loaded South African glider, and it was clear
that 'variable geometry', as the Fowler flap idea was called, was not the
best solution for scratchy weather. Under booming South African
conditions, for which it had been designed, it worked extremely well. The
BJ-2 was a tremendous achievement, several years ahead of its time. It was
also very well engineered and built - it is still flying today, 33 years
and probably at least 2500 hours later!
The BJ-3
The tremendous success of the BJ-2 naturally resulted in the design of a
successor, the BJ-3. By this time, Fritz Joel had moved to South-West
Africa, but he still did most of the drawings, aerodynamics and stressing.
Although the BJ-3 was in concept a natural evolution of the BJ-2, it was
radically different in structure. Only the tailplane was still of plywood
construction. Like all Pat's subsequent gliders, the wing had an aluminium
structure. The wing skins were foam stabilised glass fibre. The front
part of the fuselage was also of glass fibre, but the tailboom, fin and
rudder were aluminium. Aerodynamically, the fuselage was sleeker, the wing
span and Fowler flap area greater, and the wing loading higher. An NACA
66-series airfoil was used, to obtain even lower profile drag. Although
airbrakes were fitted, the drag chute was retained. Even though the glider
was built at Pat's company, Performance Sailplanes, in Germiston, it was
still very much a homebuilt. Glider building was a hobby, and not the
mainstream activity at the factory. The BJ-3 had its first flight in 1965.
In the capable hands of Pat and 'Bomber' Jackson, the BJ-3 also achieved
several world records, and won the South African championships in 1968.
The sole BJ-3 was modified to become initially the BJ-3A, and later the
BJ-4 prototype.
The BJ-4
The success of the BJ-2 and BJ-3 prompted a more ambitious scheme. Two
BJ-4's were built, with Hugh Keartland sponsoring the construction of the
second one. The objective was to win the world championships in Texas in
1970. Although visually very different, the BJ-4 was a further evolution
of the BJ-2/3 concept. The construction was similar to the BJ-3, but the
fuselage was much sleeker, and the T-tail was abandoned. A very tall high
aspect ratio vertical fin was used. The wing was essentially similar to
the BJ-3, retaining the very large Fowler flap over 80% of the wing span.
Once again, it was regarded as an extremely advanced glider. The two
BJ-4's were to be flown by Pat and Bomber Jackson in the world
championship.
The world championship was a disaster for the BJ-4. Pat Beatty was
eliminated on the first day of the contest, when a passing car struck one
of the wings of the glider, when it was being derigged after an outlanding
on a freeway! To add insult to injury, the unfortunate pilot was also
fined $ 150.00 for his indiscretion. Jackson also struggled with the
unexpectedly weak weather in Texas, and it became clear that the BJ-4 was
no match for the latest German gliders, which used simple plain flaps,
combined with very large wing spans. It signalled the end of the 'variable
geometry' trend of development in glider design. Although several variable
geometry gliders have been developed all over the world since 1970, only
one, the SB-11, has been truly successful. Both BJ-4's are still flying
today though, testimonies to fine engineering, and monuments to innovation.
The B-5
Although Pat recognised that the Fowler flapped glider had reached the end
of it's competitive era, it didn't prevent him from exploring further
possibilities for variable geometry. He did, however, first take a couple
of years off from glider development to build a very innovative,
wing-sailed C-class catamaran to try and qualify for the Little America's
Cup. With the sailing venture out of the way at the end of 1975, he
returned to the problem of building a better glider.
Now working without the assistance of Fritz Johl, the B-5 was designed to
be a truly innovative glider; perhaps radical is a better description! In
order to reduce interference drag, the wings were mounted virtually at the
front of the fuselage, and swept back slightly . To get the center of
gravity far enough forward, two streamlined balance weights were mounted on
arms in front of the wings. The camber of the wing could be adjusted in
flight, by moving the wing upper surface up or down. The wings could thus
be made thicker and more cambered for climbing, or thinner and less
cambered for high speed cruise. To further enhance low speed flying, the
wing span could be extended from 15 meters to 19 meters by means of a
telescopic wing tip!
The B-5 was first flown in 1979, but only once in this configuration - a
very nasty oscillation encountered on its maiden flight persuaded the
designer/builder/pilot to abandon the wing mounted balance weights in
favour of a single conical balance weight mounted on the nose. Version 2 of
the BJ-5 was soon replaced by Version 3, which discarded the nose-mounting
for the wing in favour of a pylon, fitted just behind the cockpit. The
objective was still to reduce interference drag. In fact, Version 3 had an
all-new fuselage, a very slender body of revolution. The fuselage was
constructed from moulded glass fibre. It eventually became clear that the
camber- and span changing mechanisms did not produce the hoped-for
advantages. Amongst other problems, the geometrical constraints of variable
span resulted in spanwise load distributions that were unacceptably poor.
The B-6
Initially flown in 1981, the B-6 used the same fuselage as the last version
of the B-5, and retained the pylon-mounted adjustable thickness wing. Very
distinctive upswept wing tips were used, on a fixed 22 m wing span.
Version 2 of the B-6 finally dispensed with the adjustable thickness wing.
Instead, the aft 40% of the wing skins were flexible, for camber
adjustment. Very small (10 % of chord) ailerons were used. The wing
structure consisted of an aluminium spar, with plywood ribs and aluminium
skins. Although performance seemed quite good, the small ailerons resulted
in inadequate feedback, which made the glider rather difficult to fly.
The B-7
The introduction of a 750 kg weight limit for the open class prompted the
design of the B-7. First flown in 1984, the B-7 retained the B-5/B-6
fuselage, but an entirely new wing of 19.5 m span was fitted. The pylon
mount was initially retained, but later discarded in favour of a relatively
conventional, but high, 'shoulder' mount. The beautiful wing is of
all-metal construction, with an elliptical leading edge. To allow a
straight aileron and flap hinge line whilst retaining the elliptical plan
form, the trailing edge is also slightly curved. Because of the very high
aspect ratio, compound curvature of the wing skins is relatively small, and
the wings were constructed by bonding the skins to closely spaced glass
fibre ribs and stringers. Small countersunk sheetmetal screws were used to
pull the skins down. Although the B-7 almost appears conventional,
compared to Pat's other innovative designs, there are some subtle
innovations. For example, the plain flaps also split differentially, to
assist circling flight. The B-7, which still flies occasionally, performs
well, and like all the successful Beatty and Beatty-Johl designs, is
competitive under strong thermal conditions.
The B-8
The B-8 is Pat's only 15 m glider. Unlike the various versions of the B-6
and 7, it was an all-new design. The glider flew for the first time in
1988. The fuselage consists of a plywood and glass fibre 'pod' with an
aluminium tailboom. The elliptic (similar to the B-7) wing
was built in a novel way. Like all the other post-BJ-2 designs, a metal
wing spar was used. The closely spaced wing ribs were made from
glass-fibre. The 'skeleton' of the wing was mounted in a jig, the moulded
glass fibre leading edge fitted, glass fibre fabric pulled taut over the
skeleton, and then wetted out with resin. Because of the curvature of the
wing, the main spar is also curved.
Version 1 of the B-8 returned to the idea of a variable camber wing. A
boundary layer suction system was also fitted, with suction slots on the
lower surface venting at the aileron hinge-gap. No performance
improvement could be measured, and the system was soon disconnected. The
variable camber was also soon abandoned in favour of Version 2, which used
slotted flaps over the full span of the trailing edge, including the
ailerons! However, the same problem that bedevilled the BJ-2, -3 and -4
was experienced - it resulted in a 'two-speed' glider: very fast and very
slow, with poor performance in between for the weak days. The final
version used a slotless area extending flap, similar to the successful
SB-11, but on a smaller wing. Development of the B-8 was still continuing,
when Pat and his wife Betty died in a road accident on 21 December 1991.
Nevertheless, the performance of the B-8 is similar to its predecessors -
competitive under strong conditions, less so when the thermals are weak.
Although the heady successes of the 1960's did not continue into the later
years, the achievements of Pat Beatty in co-designing, building and flying
no less than eight highly innovative gliders can only be described as
unique.
Charles Crosby e-mail : cro...@fanella.ee.up.ac.za
Dep of Mech and Aero Eng meg...@upvm2.up.ac.za
University of Pretoria Phone : (012)-4202861 (w) (012)-3451586 (h)
South Africa Fax : (012)-436540 (w) (012)-3451586 (h)
Craig Wall
>>
> THE HOMEBUILT SAILPLANES OF PAT BEATTY
>
> Charles Crosby
I want to thank you for this wonderful article. I was at Marfa in 1970
and saw the BJ-4. I thought it was marvelous! I was a kid that spent all
his time hanging out at a field where homebuilding was very popular, and
the craftsmanship on that glider was equal to the best. I remember being
very disappointed that the ship failed to compete. The polished metal
tail surfaces with red fabric controls was gorgeous, and a stark contrast
to the rows of white German glass. It *looked* like a world beater.
Thanks for the memories!
Craig Wall
Peter Wyld
and being a party to teaching their daughter Sue to glide at Bara-G in
the early eighties, when myself and a colleague were running gliding
courses there. I remember one of Pat's gliders had the airbrakes sealed
with masking tape which was pierced by the saw toothed brakes when
needed!
I had a lot of fun in SA, flying at Bara-G and tugging and scoring for
several years in the nationals at Vryburg. Nice people, great gliding.
Thoroughly recommended to anybody who wants some serious gliding in the
sunshine.
My best wishes to all who may remember me from then.
Pete. (aka Boris)
____|____
_\__8__/_
/ \