previous AA1A - ZS-VYI (Yankee India) - a great airplane once
it had enough power up front!
Yeah, we know
the old one about building (or rebuilding) your own aircraft - 'whatever
length of time you think it will take, just double it!"
How about changing
that to quadruple it (and the final multiple is not yet established!)
- starting in February 1994, we are now up to just over 15 (gulp!)
years, and still not done! To be fair though there have been periods
of 2 years or more when I have not laid hands on the aircraft -
off my previous Yankee in August 1993 - an AA1A modified with 150
hp up front, with which I enjoyed some great flying over 16 years
and about 1800 hours, the withdrawal pangs were setting in. After
considering various replacement aircraft, I just could not see anything
in any sensible price range (read "cheap") that I wanted
to regularly fly, I came across the fuselage and tail feathers of
a 1972 AA1B. This aircraft had, in the far distant past been ditched
in a lake near Witbank. The story goes that the pilot and a buddy
were doing a buzz job on another friend's boat, misjudged things
and smacked into the water! After the occupants swam to shore, the
plane was dragged out and dumped behind a hangar, where it lay for
many years. Coincidentally, during my pilot training at FALA in
1975 - 76, I recall being told of this incident and the wreck lying
at Witbank airfield, east of Johannesburg..
wing structure with aux tanks installed
wreck, minus various and substantial components ended up at Irene
near Pretoria, with an owner who had intended to rebuild it - however
I guess he saw me coming, and decided to take the money instead!
included the stripped down fuselage, a damaged port wing, no starboard
wing at all, the empennage, and engine mount, some damaged main
gear legs and several cardboard boxes of cables, pulleys and sundry
semi-identifiable bits and pieces, rumoured to fit somewhere on
the airframe! Towing this lot home on a borrowed trailer, It did
occur to me that I had taken leave of my senses, but I consoled
myself that the re-assembly should not be too difficult, after all
I knew the AA1 well and believed I could quickly obtain most of
the bits that might be missing - how long can it take to put together
what Grumman-American once touted as "the simple airplane"
in it's advertising? Ha, Ha!
Next step was,
of course to begin locating the missing major components, such as
the all important missing wing, gear legs, instruments and an engine.
AA1 seen at the AYA Convention held
at Cable, Wisconsin in 1989
From the start
of the project it was my intention to produce a different AA1 -
one which would nor be powered by a Lycosaurus up front, but by
a relatively efficient and powerful automotive engine. Now there's
nothing wrong with a Lycosaurus if you really like rough running
motors with a stunning 150 hp from a mere 5.7 litres! The other
thing you have to favour is spares prices that are astronomical
- one thing that always worried me about flying Lycosaurus's was
the thought that every spin of the motor brings you closer to the
day when you will have to mortgage your house to afford a major
overhaul - and perish the thought that something like a camshaft
may fail - at something like R14 000 ($1400) (excluding lifters
and new cam bearings etc.) you just don't wanna know!
EAA's big gathering at Oshkosh many times, and taken steps to meet
and talk with any owner flying an auto-conversion, I felt that I
by now had a pretty good handle on what could work in the Grumman
- and as time passed, and I talked to more owners flying behind
auto engines, it became clear that the Chevrolet 262 CID V6 motor
had potential. This motor was in use in a number of RV6 aircraft
and others - and successfully it seemed. Studying the RV6, it seemed
to me that here was an aircraft that was, in terms of it's configuration,
size, weights etc., as close as one could find to the AA1B - if
the motor could succeed in that aircraft it could surely succeed
What about the
extra weight of a V6 when compared to the Lycoming 0-320? Well,
when I converted my previous AA1A from Lycoming 0-235 to 0-320,
I added a total of 65 lbs. to the front end in doing so (a substantial
part of which was in the bigger and heavier prop).
fin added - said to make the aircraft track better - we'll
CG calcs at
that time told me to add 16 lbs to the tail at station 200.4 ins,
right under the vertical fin, to balance out the bigger motor. This
seemed like a no-no to me, and instead I filled something like 20
small bags with sand - each weighed 4 lbs if my memory serves. On
the first flight after the conversion work was finished, I placed
these bags at the rear of the baggage compartment, to simulate the
16 lbs. of ballast in the tail. After each circuit of the airport,
I landed, slid back the canopy and tossed out a couple of bags at
the side of the taxiway, and off I went again. Well by the time
I had ditched all the ballast, a bit at a time, the aircraft was
handling better than ever and I figured that 16 lbs in the tail
would not be needed. The subsequent 7 years and 800 hours of flying
proved me right and I discovered that the AA1 flies better in all
flight regimes with a bit of extra weight in the nose!
With this knowledge
I was not concerned with the thought of the extra weight of a big
'ol cast iron lump up front - with 190 hp it will certainly fly,
and we can always move the battery aft, if necessary. Of course
things like a composite prop (11 lbs against a Sensenich at 42 lbs),
lightweight (automotive) starter and alternator, will help strip
a bit of weight off - and let's dump the soft furnishings in the
cockpit, thus saving another 30 lbs.
V6 as delivered! What a sight! it was not much better on the
So the choice
of engine was made - and the next major modification was to plan
to get some additional fuel capacity. In my previous Grumman I had
a added an aux. tank in the baggage compartment, this tanks came
from a Ford Escort Mk11, and fitted perfectly just behind the seat
backs, strapped to the baggage floor panel, and feeding direct to
the fuel line running from the fuel selector the the engine. It
carried an additional 11 galls usable, and helped extend the range
very usefully. However the idea of all that gas in close proximity
in any accident was not a comforting thought. And the old axiom
that you can never have enough fuel on board unless you're on fire
definitely holds true in Africa, with avgas supplies diminishing
as our smaller airports disappear.!
This time around
the gas had to be in the wings where it belongs, so 2 additional
tubes were to be added to each wing to act as integral auxiliary
tanks. These tubes would be located in the lightening holes on the
wing ribs, which Grumman thoughtfully provided for the purpose it
seems! This mod doubles the existing fuel capacity of the littlest
Grumman, while putting the fuel where it can do little or no harm
in the event of an accident.
1989 I had flown the RV6 with Dick Van Grunsven. This aircraft was
powered by an 0-320 of 160hp with a CS prop, and the performance
of the aircraft was fantastic! This got me to thinking, why can't
the AA1 perform as well? It's a little heavier, empty, but has almost
identical dimensions. However when you look at the RV you notice
the superb aerodynamics, which are worth a lot in terms of performance.
262 cid after rebuild - still waiting for manifold and carbs
Some of the
aerodynamic features cannot easily, or at all be replicated on the
AA1, such as the lower and more streamlined canopy - but others
can, such as the smaller flat-plate frontal area, smoothing airflow
around the tail feathers, gear and wheels/brakes with sleek fillets
and firings etc. Plus of course cooling drag, one of the big speed
killers! With a properly engineered water-cooled motor installation,
this drag factor can be effectively reduced to the minimum.
my objectives for the AA1B here goes:
auto engine power of at least 180 hp
2. Additional fuel for extended range and endurance
3. Improved aerodynamics and reduced cooling drag.
simple, right! Oh, one thing I forgot - build the AA1 for less than
R120 000 ($12 000)!
cylinders and 190 hp in standard form - more power available
THE OBJECTIVES - GROWING A GRUMMAN
with something less than a flyable aircraft, there was a lot of
work on the airframe before we could even approach the exciting
bit of sorting out an auto-engine power unit.
cleaning everything, including chemically cleaning the entire fuselage
interior and checking thoroughly for any corrosion (none present,
I am happy to say) and examining the famous glue joints which hold
everything together on the AA1, we began in 1994 to start assembling.
The first task
was to get the fus. standing on it's own three feet - so I ordered
from the US a set of used main gear legs, from Ken Blackman of AeroMods
in Washington state. Ken also supplied me a used engine instrument
cluster. Also ordered a new nose leg, and once these had been collected
by a friend who himself was touring the US hunting for parts for
his own AA1B rebuild, we could get the kite standing.
to make these parts - wing tips and speaker mounting, out
Locally I sourced
a set of Cleveland brakes and wheels, reputed to come from a Cessna
182 - looked identical to the Grumman stuff, except for larger bore
caliper pistons - maybe we have better brakes now?
Once all this
was installed it was time to strip the old wings, as the Alclad
covering was beyond repair - having been battered in storage over
the years. Since the wing skins are glued with epoxy adhesive to
the ribs, it seemed that this job should be easy - just slip a scraper
blade into the glue joint and pop the skin off - right?
WRONG - I could
not believe how the glue had, after 20 years of curing, set like
steel - in fact my first attempts, before we got the smarts, resulted
in tapping the scraper bade through the wing skin - in other words
it was easier to cut the Alclad than to cut the glue!
was not going to work, and the risk existed that I would end up
hacking cuts through the wing ribs - not good. After a little thought
I realised that judicious application of a heat gun should soften
the glue enough to make it easy to get the scraper blade into the
bond-line. The concern here was that the ribs are not only bonded
to the skins, but also to the main spar, so it would be important
that our heat gun method should not result in any damage to the
adhesive holding the rib to the spar.
V6 in Cessna 172 at Oshkosh. Owner gets 160 mph cruise and
1500 fpm climb from sea level!
After some cautious
experimentation we managed to get the skins separated from the ribs
- although, even with application of heat, that epoxy did not easily
give up! And after the wings were denuded of covering there was
a big job left to remove the last traces of epoxy clinging to the
rib-flange. This we did with sandpaper, figuring that we didn't
want to put any more heat into the structure, particularly near
the centre hole of the rib, where the spar was bonded.
Now of course
we had to find some new covering - what a shock, local prices for
.020 or .025 Alclad are fierce, so we left this in abeyance for
now and carried on with other things.
The things included
installing all controls, pulleys and cables, carrying out some minor
repairs to the firewall area, installing all the tail feathers,
the canopy and windshield and the instrument panel and a set of
the basic VFR instruments. With the help of a friend, the airplane,
less the wings, was also painted.
After this the
project languished for a long time - about 2 years, although during
that period I located the engine I intended to use. This is a Chevrolet
(GM) 262 CID V6 as used in the Chev Blazer and some other US models.
The engine was purchased from American Parts Warehouse in Marshal
Street, Johannesburg, "as is" - take a look at the pic
and you'll see what I mean! After stripping, the block, heads, rods
and crank were sent off to the machine shop for boring grinding,
revalving and checking for straightness in the case of the rods.
In 1998, I was
due to travel to Oshkosh and figured that I might pick up some suitable
sheets of Alclad there. What an eye opener when I obtained 2 x 10
ft sheets of .025 and 2 x 8 ft sheets of .025 for one quarter of
the price in South Africa - and managed to get it all rolled and
boxed up for $10, and took it along as hand-luggage on the Lufthansa
flight home! These wing-skins are slightly thicker than the original,
which were .020 in alcald.
allowed me to proceed with installing new wing skins, but first
to install the aux. tanks. These had previously been welded up using
farmer's irrigation tube from local manufacturer Hulett aluminium.
With a 101.6mm dia. and 0.9mm wall thickness, these welded seam
aluminium tubes are identical to those offered in an AeroMods STC
for the little Grumman, which adds either 10 or 20 gallons of additional
fuel in the wings. The tubes are slid through the existing wing-rib
lightening holes, fore and aft of the tubular wing-spar, which also
serves as the main tank. The great advantage of this arrangement
over an auxiliary baggage tank is that there is no fuel travelling
with you in the cockpit and the additional weight of fuel is so
close to the existing CG that whether your tanks are full or empty
the balance of the aircraft is maintained.
Each tank in
my set up ( there are four, two in each wing) has it's own baffles
welded in to avoid fuel surging along the tank during sharp manoeuvres
and carries 5 galls - giving a total of 20 galls additional gas
- that doubles the standard capacity. In each wing the two tanks
are linked to be common and fuel is pumped from the auxiliary tank
set, using a single wing-root mounted Facet electronic fuel pump
on each side, to the main tank. In flight one would need to empty
the main on that side by at least half before beginning to pump
auxiliary fuel - but we now have "in-flight refuelling"
- and can get a "fill-up" anytime - handy! Total weight
of the tanks, piping and pumps - 16 lbs, seems worth it.
years ago, this(and above) is how they advertised the AA1-click
Once the tanks
had been installed, it was time to tackle the skinning of the wings
- where to start? Best place, thought I was to consult the experts
and get a price for them to do the job! Shock, horror, the prices
I was quoted seemed to take no account of the fact that I was to
supply the materials, other than rivets! Crazy money, telephone
numbers again - no go! Just going to have to go the DIY route yet
Started by making
the mistake of trying to tackle the job single-handed. Not the way
to go with 10 ft long and 4 ft wide sheets of thin and very easily
damaged Alclad. Also made the error of using solid rivets, when
the Grumman wing was never designed with these in mind, with the
result that it is really tough to get a bucking bar in to some areas,
even impossible in some instances.
job aside and giving some consideration to these newly identified
difficulties led me to changing over to blind rivets and getting
another pair of hands in to help. The rivets are the Avex type (locally
available), and metallurgically exhibit similar strength to the
solids, but are so much simpler to place. Once we had rearranged
things along these lines, we were ready to proceed once more, and
with assistance the job came together well. I also used epoxy adhesive
on the rib flanges, where the sheets would contact the wing structure,
but I wasn't prepared to rely totally on the gluing method, thus
the rivets. When Grumman made wings, they had all the jigs, cradles
and clamps to hold the skins on nicely, while everything cured under
heat in a big oven, which is how they achieved excellent results
- doing the same job in the less than perfect conditions of my garage
at home was not going to give the same result, to my way of thinking,
therefore the "belt and braces" approach.
One of the biggest
parts of the riveting job on the wings was the dimpling of each
hole, to allow for flush rivets - and this has to be done on the
wing skin and the flange of the rib where the attachment is made
- but well worth it I think, as after lightly milling each rivet
to ensure a flush fit, then epoxy-filling each rivet-head as necessary,
the wing looks like the original with not a rivet in sight! - and
that's gotta be worth a little speed. Once completed the wings were
painted to match the fuselage - fortunately I still had enough 2K
paint from the previous painting job, which of course matched perfectly.
After all this
extended effort, and having moved the aircraft from my home, where
it was taking up too much space, to Baragwanath Airport, SW of Johannesburg,
we took a break - a long break of about 2 years again - we'll get
to the recent triumphs and tragedies in the next instalment!