|
|
 |
     |
|
|
|
|
|
|
|
Alien Saucer plans are available from: Airborne Plans Service for AU$33.00 plus P&H1 (AU$2.00 within
Australia). Plan No. 653
Scramble - - Alert ‘Williamtown RAAF fighters go on alert! Strange sightings have been reported over Ash Island, Newcastle'. But wait, it's only a new design from Airborne being test flown. It's their Alien Saucer! Phew! Now that all the commotion is over, let's look at what this strange craft is and how you too may have one in your hanger. This craft is unusual to say the least! It is a one metre diameter circle (the wing) with a 400mm circle for the horizontal stabiliser, set 200mm above the rear of the wing and fuselage that can only be described as 'cartoon character' style. It does not look like anything that I would describe as an aeroplane. but is does have a sort of an appeal, if you like something that is a little different. The first thing you will need is a board that is large enough for this project, as the wing is a one metre diameter circle built in one piece. The fuselage is then built over the wing. So let's start! The board needs to be a least 1200mm x 1200mm to give the minimum working area required. Be sure that it is flat and true because this determines how true the wing and the rest of the construction will be. (Check the article in number 162 in "Focus with Foley" for one method of achieving this result). After this is achieved it's time to get on with the construction of this flying machine. Construction The usual recommendation is to make a kit of the parts. I traced the ribs, formers and outer rims of the main wing and horizontal stabiliser onto grease-proof (not waxed) paper to make it easier to transfer these onto the appropriate balsa and ply sheeting. The kitting process needs to be done carefully particularly when cutting out the ribs. Care is needed not to place too much strain on the balsa because you will find that these will split in areas where the lower and upper spars come close to each other, especially for ribs R1 (toward the trailing edge), if you are not using a good sharp blade. Also when cutting out the outer rims of the main wing and the horizontal stabiliser it is important to get the cuts as vertical as possible so that joining will be neater and require less sanding. These joints may be sanded to give a better fit later if needed. Wing (1 metre diameter circle)
Tailfeathers
Fuselage Construction of the fuselage for this model is different in that it is built over the wing and attached to the wing, permanently. But start by joining the two 3mm balsa pieces that constitute the top part of the fuselage sides (if using 100mm wide balsa) and then laminate the 1.5mm ply doublers in place. This will leave fuselage sides that have doublers extending past the balsa, ready to have the lower fuselage sides glued in place. Formers F2a to F5a are then glued at right angles to the inside of one top fuselage side, along with the 6.5mm triangular balsa stringers and the 9.5mm x 3mm spruce radio hatch opening side strengtheners to both sides. The fuselage side with the formers attached now needs to be slid over the wing once the wing outer rim has been shaped to the profile shown on the plan. This shaping was done by both razor plane and sanding. When happy that the fuselage sides will fit snugly in place and the outer rim is the desired shape, glue the fuselage side with the formers in place (you did mark where they were to go didn't you?). Then slide the second fuselage side in place and glue it to both the formers and the wing. The lower section of the fuselage I made as a unit ready to be added later. This was done by firstly laminating the two F2b's (3mm ply) and attaching the nose leg to them and then attaching formers F3b to F5b at right angles to the lower part of the fuselage side in the appropriate locations making sure to locate the two 1.5mm ply plates (R) just behind F4b and epoxy the blocks for the main undercarriage. Also the 6.5mm triangular stringers need to be attached along with the necessary gussets behind the undercarriage blocks. Attach the second side using epoxy and aliphatic resin and set aside to dry. Once this is dry it then is necessary to laminate the doublers to the fuselage lower sides. I clamped the lower fuselage to the doublers while the glue dried and then glued this section to the underside of the wing. After overnight drying the grooved block cross section of the main undercarriage support was fitted with epoxy and drilled to accept the 5/32 undercarriage legs that were bent according to the plan. The F2b former is now epoxied in place because this former has the nose wheel attached. With all this done former F1 and fillets, with engine mount fitted, can now be added using epoxy. Ensuring both down thrust and side thrust are set as per plan. The 3mm balsa cross grained bottom sheeting is now fitted.
Finishing This brings us up to where we can finish with our favourite covering and/or paint job. But you say that the tailfeathers are not in place. That is right, they aren't! I decided to first cover the tailfeathers, dope and paint the fuselage and then cover the wing, and then attach the tail. Let me explain! The tail is unusual in shape and is easier when attacked separately. I chose to cover these with chrome heat shrink, but failed to notice a small sticker that said that this particular covering was only to be used on solid areas. So when this failed, due to my oversight, I covered the tailfeathers with tissue and dope, and painted them chrome and set aside to dry. Next I doped the fuselage, sanded with 180 wet and dry (used dry) and then used a mixture of dope and talc for the final doping, sanding with 400 wet and dry (again used dry) to give a smooth finish. then the wing area was masked and the entire fuselage (top and bottom) was painted, also with chrome. The tailfeathers were test fitted and positioning checked, making spacers to temporarily position this assembly, then again removed. Now I covered the wings with chrome purple (underside) and chrome blue (top) heat shrink. This covering was Profilm and worked magically giving a great finish. After the covering was applied and I was totally happy, I ironed the areas where the tail was to be attached. Then I cut slots out of the covering to allow the tail to be epoxied in place, again using the spacers made previously to aid alignment.
To The Flying Field The day finally arrived and once at the field, the mandatory photos taken, the usual checks were made, controls working in the right directions, throws set on low rate the range check done, it was time to start the engine and fly. The engine started after only a couple of flicks and once, tuned, it was time to go onto the strip. You need to place this model on the strip, facing into the wind because there is no steering or rudder control. The engine was again run up and then back to idle ready for take-off. Everyone at the field was watching as I opened the throttle and away it hurtled down the strip and with about 8 to 10 metres jumped into the air and was going into a vertical (bordering on looping climb, full down was applied to little avail so rates were turned off and control was almost mine. This flight was very interesting to say the least. There was a breeze blowing from the western end of the field and when flying into the wind the model would either climb or dive rapidly with the movement of the controls. It appeared to be more stable travelling down wind, so it was decided to try a slow run, at altitude, to see if it might be better to land with the wind, but as the model slowed it just weather vaned and turned into the wind. To cut a long story short I finally got the model down to the applause of all who were watching. Our club president said maybe I should have bought it in knife edge and let it roll along. From this I deduced that the C of G was too far back and with my nerves settled, packed up and went home to sort out the problem. Through the week I moved the C of G forward to 29cm from the leading edge by moving the battery pack in front of the tank and adding some lead. Back To The Field
Conclusion This model is great fun to fly - a real attention getter and because of its unusual appearance something different for the modeller to build and fly. I do not think that it is one for the beginner, but could be handled quite easily by someone who has been flying low wing for a little while. All in all, this has been an enjoyable project and has been very satisfying to see the finished model in the air. SPECIFICATIONS Alien SaucerWingspan Diameter: 1.0 metre Alien Saucer plans are available from: Plan No. 653 To return to Airbornes
home page This page was last modified on the 19 May, 2002
|
Alien Saucer dispells any doubts about the existence of
UFOs... this one's for real!
This is built in
one piece and is to be built first, you really don't get the
option of building the fuselage first, but you may decide to
build the horizontal stabiliser first if you wish. Start by
laying out the plan with your favourite protective covering. Mine
is to use plastic cling wrap. Next trial fit your outer rim
(leading edge, trailing edge, come wings tips) made from 12.5mm
balsa, sand and fit until totally happy that it fits the outline
on the plan and the joints are flush. Then glue these together
with the aileron (6.5mm x 12.5mm balsa) in place, ensuring that
they still follow the outline and are pinned securely to the
building board. I chose to use aliphatic resin for these joints.
After this is dry the lower spars are pinned in place, noting
there are three 6.5mm square balsa spares and one 9.5mm x 3mm
spruce spar. Ensure they fit well and then glue these in place.
Before starting to put the bottom sheeting in place MARK the rib
locations on the spars, aileron hinge support spars and the outer
rim because this will be needed after the bottom sheeting covers
their locations. Once this is done, put the 2.5mm balsa bottom
sheeting in place noting the direction of the grain. Next the
ribs are test fitted and when sure of the correct locations and
fitment, use a square and glue ribs in position (thin Zap used
here), starting from W6, working to W1 as this gives more room to
use the square. The top spars can now be added and after these
are glued in place flush with the tops of the ribs and tapered
where they join the outer rim, the top 2.5mm balsa sheeting (back
to the main spar), cap strips and trailing edge sheeting (upper
only) can be added. When I put the top sheeting on I ran the
grain in the same direction as the main spar. Be sure to remove
any pins that could be sheeted in or else there could be some fun
getting the wing off the board later. Leave this all pinned to
the building board and now build the ailerons directly over the
plan. The ailerons are quite simple to build, being made from
12.5mm balsa. Once happy that this is all dry you can now remove
all the pins and remove the wing from the board and roll it into
a corner for later attention. Note:- before removing the wing
from the building board be sure to mark the centre line and where
the fuselage sides are to be located near the leading edge
(making sure to extend the line far enough so that after shaping
the leading edge and sanding the top sheeting, the line will
still be visible) and at the trailing edge. You may decide to
shape the rim to the desired profile as shown on the plan at this
stage, but I left this until I was ready to fit the fuselage over
the wing.
The horizontal stabiliser is built directly over the
plan from 9.5mm balsa. Pin down and glue the outer rim, then it
becomes just a matter of cutting the 9.5mm balsa 'ribs', fillets
and hinge supports, laying them in place over the plan and gluing
together. One thing I added was a section in the centre to
support the nyrod that I chose to use for the elevator control.
The two vertical supports (fins) are also made directly over the
plans from 9.5mm balsa and then pinned together and sanded both
top and bottom to give the desired 0 degree incidence alignment
for the horizontal stabiliser. Attach the vertical supports to
the horizontal stabiliser using epoxy or your favourite strong
glue, BUT DO NOT attach to the wing yet.
The top of the fuselage is a little more involved to
complete. Start by cutting out the tank compartment hatch and
front decking from 6.5mm balsa and attach the decking in place.
Now cut out the shape for the roof section of the cockpit from
9.5mm balsa and use 3mm balsa to form the windscreens are per
plan. The radio compartment hatch is made of 9.5mm balsa and
across the rear of this opening a cross piece of 6.5mm square
balsa is attached to give an attaching point for the top sheeting
and to strengthen this area of the fuselage. There is one more
addition to this fuselage, and that is the blister with the
antennae on top of the radio compartment hatch. The blister I
made from two pieces of 12.5mm balsa laminated together and
shaped, and then the antennae from 1.5mm piano wire with
polystyrene balls epoxied in place. As stated earlier I chose to
use a nyrod to control the elevator and I also used nyrods for
the ailerons. When happy with the setup of the controls, the rear
3mm balsa top sheeting, cross grain, may be added. Lightweight
filler was used where the fuselage and the wing meet to give a
neat clean finished look to the joint. Then entire airframe may
now be sanded to shape and smoothed with finer paper ready for
finishing.
The radio gear, engine (OS 46FX) and fuel tank where
fitted and the model was balanced to what I had worked out to be
the balance point. The throws were set as follows, elevator (both
up and down):- low rate 25mm, high rate 40mm, and ailerons:- low
rate 15mm, high rate 25mm. Both were measured on the centre line
of the fuselage. The finished model weighed in at just over 5lb
or 2.2kg.
This time the story was different in that I made about
half a dozen attempts to get airborne but to no avail. After each
attempt adjustments were made to control surfaces because it was
believed that it would at least fly with the C of G set here, but
I ended up having to move it to 31cm from the leading edge before
being able to get the model to rotate. This time the flight was
controllable, and enjoyable. The model rotated after about 18 to
20 metres and climbed smoothly. Once in the air it was fun to
fly, being able to do loops, barrel rolls, stall flips. I decided
to get some altitude and see what happened when the model was
brought to a standstill (stall) into the wind. This was very
interesting in that it did not drop the nose or a wing, it just
did a pirouette and turned down wind and glided away. Landing now
is easy in that it flares very nicely, making contact with the
main gear first and then the nose comes down. One of the club
members said that it looked like a real pussycat to fly. The only
point is that the C of G is critical, because at 31cm when you
take off with a full tank (10oz) of fuel and set the trim it
becomes necessary to change this as the fuel is used.