The Hafner Rotabuggy
Rotabuggy Main Page
- a standard Army "Jeep" with
free-wheeling rotor and stabilizing tail unit.
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 Austrian Raoul Hafner began
preliminary work on helicopter models in the mid 1920s, and in
1928 began the design of his first aircraft, the Hafner R.l helicopter
Financed by the Scottish cotton millionaire, Major J. A. Coats,
this had a comparatively short fuselage and a large diameter
(9.14 m/30ft) three-bladed main rotor; power was provided by
a 22 4 kW (30-hp) ABC Scorpion flat-twin piston engine. When
tested at Vienna in 1930 it was soon found that the gyroscopic
action of this rotor was too great and as a result, only a few
brief hops were made.
Raoul Hafner's wartime work included the design and development
of the Rotachute, a man carrying glider with a rotating wing.
Towed by an aircraft to he~ghts of some 1220 m (4,000 ft), it
could be piloted in any direction after release. This was seen
as a stage in the development of a man carrying 'parachute' with
a rotating wing that could be carried in an aircraft in a folded
state and would deploy automatically when used in an emergency.
Other wartime work was concentrated on the development of a Rotabuggy,
basically a 'jeep'-type general-purpose military truck with an
easily attached/detached rotary wing that would allow such vehicles
to be towed and deployed behind enemy lines. A prototype was
flown extensively during 1943-44, but did not become operational.
In the postwar years, Raoul Hafner's great experience of rotating
wings proved valuable to the Bristol and est;and aircraft companies
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The first trials connected with the development of the
Rotabuggy consisted of loading a Jeep or, more formally, a Willys
Truck 4x4 model MB, with concrete and dropping it from heights
up to 2.35m to ascertain the amount of g that could be absorbed
without incurring damage. It was found that 11g could safely
be accepted, and a two-bladed rotor with a dimeter of 12.40m
was the fitted, and a streamlined tail fairing, tailplane and
twin fins (no rudders) were applied, together with a "hanging"
control column, a rotor tachometer and glider navigational instruments.
The Rotabuggy was first towed along the runway at high speed
behind a 4.5l supercharged Bentley, eventually attaining towed
airborne speeds up to 105kph IAS, the Rotabuggy becoming airborne
for the first time on 16 November 1943. These trials took place
at Sherburn-in-Elmet, near Leeds, where, eventually, the Rotabuggy
was towed into the air behind a Whitley. The initial test behind
the Whitley allegedly left much to be desired, the "hanging"
control column threshing about and the "pilot" having
to exert all his strength to maintain control.
The initial problems were progressively ironed out, and the
general handling and flying qualities of the Rotabuggy were eventually
described officially as "highly satisfactory", but
the availability of vechicle-carrying gliders rendered further
development unnecessary.
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The work of the Airborne Forces Experimental Establishment
at Ringway, Manchester, on the Rotachute from 1940 onwards led
to the suggestion that the free-wheeling autogyro principles employed
could also be applied to larger loads. The designer, Raoul Hafner,
suggested the Rotabuggy, a Jeep (or "Blitz Buggy") with
rotors, amd the Rotatank, a similarly modified Valentine tank.
A development contract was placed with the M.L. Aviation Company
at White Waltham in 1942, covered by specification 10/42. Preliminary
tests involved loading a Jeep with concrete and dropping it from
heights of up to 7 ft. 8 in. (2.35 m.), demonstrating that the
standarg vehicle could survive undamaged from impacts of up to
11g. A 46 ft. 8 in. (12.4 m.) dia. two-blade rotor was then fitted.,
as well as a streamiled tail fairing with twin rudderless fins.
Other additions were perspex door panels, a 'hanging' rotor control
next to the steering wheel and a rotor tachometer and glider navigational
instruments.
The Rotabuggy, camouflaged, carrying RAF roundels and a prototype
"P", was tow tested behind a 4 litre supercharged Bentley,
and achieved gliding speeds of up to 65 mph (105 km/h) IAS. The
first flight was made on November 16, 1943. Later, some flights
were made behind a Whitley bomber from Sherbourne-in-Elmet. One
witness described how she watched a Whitley take off with a Jeep
in tow, circle and land. The Jeep, still in tow, did not touch
down at the same time, and the witness realised that its occupants
"were unhappy".
With the pilot holding the hanging control column and the driver
clutching the steering wheel, the Jeep made a series of up and
down movements, whilst the audience hoped it would stall on a
'down' rather than an 'up'. This it fortunately did, the driver
taking over and driving flat-out after the Whitley, to which it
remained attached. When it stopped, nobody got out for a while;
the pilot was then assisted out and lay down beside the runway
to recover. Apparently he was exhausted from trying to control
the joystick, which had whipped in circles for the whole flight.
Apparently this flight was one of the worst, and the handling
and flying qualities of the Rotabuggy were officially recorded
as "highly satisfactory", especially when large tail
fins had been fitted and greater rotor blade articulation provided.
However, development of Horsa II and Hamilcar vehicle carrying
gliders made further development of the idea unnecessary.
| The Rotabuggy had a gross weight of 1411kg
of which 964kg was the empty weight of the Jeep and 249kg the
weight of the rotor unit and tail. The design max speed was 241kph,
and estimated rates of descent ranged from 4.9m/s to 10m/s. The
minimum take-off and landing speed was 58kph, and basic and max
sea level rotor speeds were 230 and 260rpm. |
chip's note: (this is where he ALWAYS gets into trouble...)
Can you imagine decending in a jeep at 10 meters/second... That's
like driving off the roof of ONLY a flippin' three story building!!
No wonder the .gov was 'pleased' with it's performance.. hehehee
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 Good morning Sir Chip:
Finally, we were able to survive the landing of the jeep insurgency.
Pix herewith and comments on the assembly:
The beta model had two pieces that looked like wheel wells
for the rear of the contraption but I did not use them.. Also
I noticed on the Alpha model that these pieces were gone. I also
noticed a change in the bumper and the brackets.
To mount the rotor I used a piece of aluminum tubing into
which a pin was used for the shaft. The breeze kept the rotor
rotating outside while I made the pix...pretty cool...but the
funny thing was, she never blew over....must have been the six
cases of Beefeater that was stowed in the back.
Again, I used the O-rings for tires and, of course, they will
roll. I had a little trouble matching the windshield lines to
the jeep body on the
sides as you can note and I wasn't quite sure how to mount the
pitot tubebut I gave it my best shot.On the beta, if the bends
on the lower rear section tabs aren't exactly to line, then the
rear end doesn't meet. The model is so exact. Wayne must be an
areteriole and ganglion brain surgeon. I used a coffee stirrer
wooden stick about 1/2 inch long for the center of the rotor.
As you said, look how cool the blades droop! I'm still trying
to figure out how to mount the two Jetex 50's on the rotor tips......a
thought generated by the Norflugel.......of course I'll have
to build the larger version to do it...this one is too small.The
soldier shot a squirrel before he left. The P-40 pulled him off...he
said something about a Belushi pilot with a cigar.... Hope this
helps out! Duckbarn
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The ROTACHUTE....
Rotachute Mk.II on mobile test unit.
Raoul Hafner had created his first aircraft design in Austria
in 1929, a helicopter. He came to England where he proceeded to
develop a somewhat successful gyroplane. He continued with other
designs, some tendered to requirements of early Air Ministry helicopter
specifications.
By 1940 he was in charge of a rotorcraft team at the Airborne
Forces Experimental Establishment at Ringway, Manchester, where
the idea of using a rotor instead of a parachute to more accurately
deliver personnel into enemy territory was developed. 
On October 3, 1940, work began on what would become the Rotachute;
practical testing began only eight days later with 3 ft. (0.91
m) rotor blades attached to lead ballast. Test drops from a Whitley
bomber showed that, whilst the models lacked strength, a properly
ballasted rotor could achieve stable flight. A new model with
two metal blades and a total weight of 5 lb. (2.26 kg) was built,
and launches from a Whitley on October 16th and from the interplane
struts of a Tiger Moth on November 7th were only partially successful,
but on
November 15th a good descent from a Tiger Moth was achieved. The
next step was to build a larger model with 10 ft (3.05 m) rotor
span and weight of 1000 lb. (45.3 kg). After stability tests on
the ground on February 19,1942, the model was successfully launched
from a special structure on the interplane struts of a Boulton
Paul Overstrand bomber, near Manchester on March 14. The model
descended from 2,000 ft. (609.6 m.) at 1,500 ft/min (7.6 m/sec).
Meanwhile, from late 1940, Hafner had been working on the designs
of a full-scale Rotachute. One concept was to carry several in
a rail on the top of a modified troop-carrying aircraft and launch
them rapidly, one after the other, from the tail end, to land
in as tight a group as was required. 
The Rotachute was designed to fit criteria of simplicity, light
weight and reliability. It comprised a steel tube frame to seat
the pilot, a two-bladed rotor with freely flapping blades, and
a rubber mounted skid. The rotor hub was also rubber-mounted,
to dampen vibration and to function as a control hinge. The fuselage
was open at the front. A tapered fairing behind the pilot stabalised
the craft, and this was made entirely of rubberised fabric, with
no framework, and was inflated to shape, with the intent of minimising
stowage space.
Control was by means of a single stick fixed to the rotor hub.
Turns were simply a product of banking. As designed, the Rotachute
had a weight of 50 lb. (22.7 kg) and a useful load of about 240
lb. (109 kg.), which might comprise the pilot, his parachute and
a Bren gun Mk.1 with 300 rounds. The rotor diameter was 15 ft.
(4.57 m.), making it the smallest man-carrying vehicle capable
of controlled flight ever built to that time. Contracts for Rotachute
production were placed. Before flight trials began, tests were
made with rotors and a complete unit fixed to moving vehicles.
Early in 1942, the first flights took place. Two trials at Ringway
in February ended with heavy landings, the craft overturning and
breaking the rotors. A third run on a longer runway at Snaith
was a little better, and it was decided, at least for training,
to fit a three-point wheeled undercarriage (rather than a jettisonable
trolley), anf stabalising fins. This required an extension of
the tail fairing, which could no longer retain strength sufficient
to avoid fouling the rotor without additon of a frame. A light
frame and tailplane were added, the whole being inflated by ram
effect from forward movement. This, the Rotachute Mk.II, first
flew in late May, 1942, towed behind a Jeep for about 15 seconds
of flight. Further tests led to satisfactory ground-initiated
flights of two or three minutes. Work now began on the Mk.III.
Tests began at Ringway of the Mk.III in June 1942, with towed
flights of around four minutes ending in controlled
landings. A totally free landing followed. The Rotachute was then
towed behind a Tiger Moth until it, but not the tow aircraft,
achieved takeoff. Further flights led eventually to towed air
launches, the Rotakite reaching altitudes of up to 3,900 ft. (1189
m.), and reaching 93 mph (150 km/h) and flight duration of up
to 40 minutes.
Subsequent tests using the Rotachute were concerned with development
of the Rotabuggy, a Jeep fitted with a rotor and tail unit in
much the same configuration. the Rotachute was developed to a
Mk.IV, with vertical fins added to the tailplane.
The Rotachute was found to be a fairly simple machine to fly and
to land in a restricted area. However, the operational needs for
which it was designed never materialised. Rotachute experience
did provide a basis for much of today's knowledge of light rotorcraft.
RETURN TO HOME PAGE
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To share with you, dear modeler, we've kept the running comentary
Wayne sent in as he was designing this little puppy.. This colorful
documentation is as interesting as the model itself.. |
Wayne sends us these
photos of his first mock up. Note that the next step is to widen
the front section. He'll also be figuring out the connection
method of the tail. Details are still sketchy which is good.
BUT his work area is MUCH too tidy! hehehe The plans shown below
were used for the model
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Well, after three gallons of glue (I really like "Elmers"
glue...next to theWASP stuff), a ream of paper, sixteen blades
(I prefer X-acto blades, no.11's) and nine thousand hours I'm
10% done...
Have a look, give it grief and make some suggestions (please
be nice, I don't think it'll fit comfortably where I fear some
suggestions may be directed)...
Whew! This de-zy-nin's fun...ZdS
Look how the tail surfaces are angled inward slightly
for additional stability in flight. And how the roof is raised
to accomodate the rotor support structure
BTW: I started to give the Flying Jeep a little colo(u)r and
have been
using the Hurricane (lovely bird, Chip) as a "go-by."
I initially gave the
underside the same underside colo(u)r as the Hurricane but then
stopped
myself (as though something like a gaggle of jeep dropping from
the sky
required stealth). Any advise on how much detail to add to the
undercarriage? In my research I have found a good number of photos
illustrating the underside of jeeps but I don't want to get too
carried
away. Although, the more I think about it, if its just colo(u)ring
it
coidn't hoit. Wayne
Working on cool(u)ring/detailing/instructions.
Might be ready, oh, let's see... Maybe June (notice I didn't
say WHICH June)...The bad thing now is that I can see the headlight
of the on-coming train I'm thinking about the next one or two
or three (spotted a dandy 3-view of the Weir (1934) W-2 Autogyro...
Should be much more simple than the PA-36; straight cones and
cylinders). But enough of that, back to the Jeep.
By the way, would things be identified as belonging on the right/left/front/rear
or starboard/port/forward/aft? Being of British design the driver's
side would be on the right which precludes driver's side vs.
passenger side...Oh why didn't I design a shipping container?
Why oh why oh why?
Having more fun than's legal in most country's, I remain,,,,,
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(Designer's notes....)
Man With Fire From Bottom,
This beast was an obvious failure (it'd only take something
like 72 MPH so
the tow planes didn't like it; something like the tow planes'd
fall outta
th' sky, or something like that). I'll put together a quick summary
in a
short-short...I'm smack in the middle of gittin' th' front "straightened"
out.![]()
As best as I can find the thing was supposed to be somewhat
disassembled
once on the ground (from the looks of one pic I've got, I'd suggest
it'd
hafta go through some re-assembly as dis-assembly would appear
to occur upon "landing"; see attachment).
The Rotachute's next (god, I AM weird)
Thank god its a Brit design...We Yanks git th' piss taken
outta us often
enough as it is...
Should have said something about
that windshield and construction order. The best luck I had was
attaching the windshield to the top then to the body; sort of
working one's way around clock or counter-clockwise (or should
that be anti-clockwise?) from the first straight place nearest
the front. I added the tabs at the last minute...I HATE tabs
with a deep and abiding passion but I also realize many people
use them...so there they are. I'll kill 'em (a vote of two counts
heavily...no recounts...no court cases...no appointed presi...oops...don't
do down that road boy).
I also have a former in there that goes under the cowling I also
HATE formers but just couldn't quite get away from it. I noticed
that by the time the windshield got stuck on the hood had a viciously
noticeable sag. I'd hoped the tolerances would be such that the
damned thing just sat there perfectly awaiting a drop or two
of glue (I prefer Elmers ;-) to hold it all together. Alas 'twas
not to be...
Suspension? Oh how I wanted to but the part count is already
in excess of thirty and I wanted to keep this fairly simple...The
suspension should be fairly straight forward...Lemma give it
a go. Maybe an "upgrade?"
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