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Delstar plans are available from: Airborne Plans Service for AU$33.00 plus P&H (AU$2.00 within Australia). Plan No. 667
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DELSTAR

by Brian Lockett & Matthew Jacomos.

The Delstar is a cranked arrow delta wing
that is striking, both in flight and on the ground.
It represents an intermediate step between
traditional prop planes and ducted-fan
or jet-turbine aircraft.
Batman colour scheme makes the Delstar look very fast even when stationary

With a 1300mm span symmetrical aerofoil wing and an overall length of 1200mm this is one big platform and mostly all wing. The fuselage just comes along for the ride.

The plan calls for a .46 to.60 size two-stroke engine. Please note that we subscribe to the 'more is better' philosophy where power is concerned and advise that you cannot have too much of a good thing. Remember that in this tail-less design, the more motor added at the front, the more lead added at the tail, leading to degraded vertical and unpowered gliding performance.

After test flying the aircraft with a Magnum .61 PRO SE we can advise that if you use a .46, it had better be a piped OS .46FX at the very least or you're going to need a looooong runway!

You could use a standard four channel radio with mechanical mixing, if you are a traditionalist, but a computer radio with elevon mixing functions no longer busts the bank and computer travel adjust and end point adjustment simplifies set-up so much that it should be mandatory on all transmitters.

There is no rudder on this bird but you do have a steerable nose wheel, (as elevons don't help taxiing very much), so four servos are all that is required.

The maiden flight was conducted in less than perfect conditions, hot gusting wind came from all points of the compass, and of course the Magnum had to flameout for the only time that day.

The Delstar is a very easy ship to fly showing no nasty handling traits in any facet of it's wide envelope. The glide rate is also very good, (this ability helped avoid disaster on the maiden flight). However, with no rudder control, a well set up landing approach is required. Whilst good training in approaches is a benefit derived from this model, it is not absolutely critical to land it like a ducted-fan model because you can go around easily enough.

This is one big wing platform which needs careful assembly to achieve full symmetry.
This is one big wing platform which needs careful assembly to achieve full symmetry

Aerobatic antics performed by test pilot 'Mr Damage' included inside and outside loops, rapid twinkle axial rolls, barrel rolls and the intriguing 'double-cut roll'. The stability inherent in the Delstar  made these aerobatics very easy to do. With a wing that does not know right side up from upside down, due to its zero pitch trim, inverted flight is a doddle. This ship will make you look good at the field.

The twinkle rolls are particularly impressive, at high rates the roll rate must approach 720 decrees per second. Not bad for such a large area of wing. Without rudder, knife-edge flight suffers but the Delstar flew some 50 feet before the nose dropped appreciably.

A peculiar characteristic to Delta aircraft is the way they look in the air. The Delstar is always a triangle and if you can imagine trying to interpret what a triangle is doing from 100m, trying to distinguish slight differences in pitch or roll is going to require good ability.

Don't take your eyes off this bird and always FLY it. It's not too demanding but it is different to a conventional aircraft. As a bronze-wing pilot of dubious ability, I flew the Delstar through several figure eight circuits on a low throttle setting with no dramas (except for forgetting to breathe!).

The Delstar should be good for the speed differential event at your local club because it dribbles along so slowly it is remarkable. A slight tendency to veer off the flight path at super-slow speed is the first warning that you're too slow. A mushy nose down attitude and attendant loss of height represent the stall. All in all, it is a docile aircraft at low speed.

SO YOU WANT TO BUILD


A DELSTAR?
You will need a large building board at least 1300mm square. Pre- kit the aircraft components as much as possible before assembly. Using Scotch 'double stik' brand tape, double-up two sheets of wing rib material. This saves time by cutting two ribs at once. Arrange rib templates so as to conserve material, as some individual ribs take up a whole sheet by themselves.

THE WING IS THE THING


The wing is of cranked arrow planform, (this is also known a double delta shape), with no reflex, either built into the wing, or set using the aileron trim.

The wing has no dihedral and has equal taper top and bottom, leading to an 'above the board build'. This simply requires  spacer blocks to position the leading edge (LE) and trailing edge (TE) off the plan in alignment with the centre of the ribs. The LE and TE are built parallel to the building board, using the spacers described below.

Cut the leading edge and the trailing edge and mark the inside centre line for future reference in rib alignment. Splice together LE and TE. Scrap balsa blocks cut to length form the spacers mentioned earlier. Tack glue these spacers to the underside of the LE and TE at roughly equal positions. Mark centre line on all ribs and chamfer the front of each rib to match the LE sweep. Left hand ribs require drilling for Rx antenna and should be done at this time.

Tack ribs & centre braces inplace with fast CA. This is where marking the centre lines will be appreciated. Use a setsquare to ensure your ribs are vertical!

Fit top spars and CA in place. The structure is now rigid enough to invert in order to repeat the process with the bottom spars and fit undercarriage blocks. No spacers are required for the top of the wing as all building is carried out 'right-side-up'.

Turn wing back over and pin down spacer blocks to secure the structure to the board. Now go over all CA joints with suitable wood glue. Great Planes aliphatic is out glue of choice.

Separate Servos in the wing control aileron movement.Set up everything before final sheeting
Separate Servos in the wing control aileron movement.
Set up everything before final sheeting

During the drying time you can now assemble the fin over the plan and glue the sections together. The really conscientious will laminate the elevon strips as well.

Once the wing is dry, a sanding bar can be used to remove any high spots on the ribs. Champher the front half of the ribs to aid in fitting the skins.

Mark and cut the skins. Careful planning with cardboard templates will minimise wastage.

Technique in fitting skins is to skin the whole top surface and underside leading edge skins. Then stop, as you will need access to the underside to mount servos and gear.

Whilst the big bird inverted, glue 3mm ply servo mounts for throttle and steering servos to the inner top skin. Mount servos.

Hardwood bearers mount the elevon servos in commercial servo boxes.

Using your method of choice, carve sand, slice and dice the LE to profile.

FUSELAGE NOSE SECTION


The power pod begins at this point. Think hard and visualise the steps before attempting this section. It's not difficult, but it is tricky. You are going to construct a box that slots into the wing. It must be built in situ. However, it must be removable during the construction process and for finishing. If properly built, the pod will self align. Use glue sparingly so that you don't bond the pod to the wing prematurely.

Dry fitting F1, F2 and F3, construct the pod inside the wing box, into the wing recess. The triangle gussets form the corners of the pod. Make sure the pod is square and true. Once fit is OK, glue the assembly together. 

Mark the horizontal thrust line onto F1. Slide the pod back into the wing bay, lining up the thrust line with the mark on F1.


Ensure F2 is flat against former W then carefully glue the pairs of FS1 and FS2 in position.

DO NOT ALLOW THIS PROCESS TO BOND POD TO WING!!!!!

Remove pod from the wing. Glass the tank bay with 4oz cloth & epoxy. Once the epoxy is cured, mark and drill holes for engine mounts, (note 2 degrees right thrust), and nose leg mounts in F1 and mount these items in place.


Slide pod into wing, fit cable snake outers for throttle and steering but only glue snakes into wing section, not pod section.
Remove the pod.

Fit top skin and lite ply bottom sheeting and, using countersink self-tappers into ply blocks, the fuel tank access hatch.

Engine firewall, tank bay and nosewheel assembly. Simply fits onto the delta wing Access Hatch for steerable nosewheel
Engine firewall, tank bay
and nosewheel assembly.
Simply fits onto the delta wing
Access Hatch for steerable
nosewheel

The cowling is next on the list and can be fixed or removable. A fixed cowl was used on the prototype for simplicity. Extra fuel proofing during finishing will ensure engine oil does not rot the cowl away.

Once the basic cowl blocks and nose ring are fitted, (12mm light balsa block in our case), carve and sand the pod to final shape.

WING AGAIN


Complete the bottom sheeting. You will need to incorporate hatches and cutouts, as well as the Rx antenna tube.
Lightly fix elevon strips in place with aliphatic glue at root and tip, and double stik tape at the centre.
Glue tip blocks into place.

Carve and sand whole wing to shape. When sanding elevons use the 3.2mm centre lamination as a guide. Once tissuing is complete the elevons can be cut free.

FUSELAGE TOP SECTION


Main fuselage section is constructed over the wing and is straightforward in its method.
Mount the formers to the wing with aliphatic and tack with CA. Tack stringers to formers whilst soaking the sheeting in cloudy ammonia to assist in moulding the sheeting over the basic frame.

We moulded the ammonia soaked fuz skin around a suitable diameter tube with masking tape and let it dry completely before fitting.

Tail cone is listed on the plan as solid block with a hollow for tail ballast.

This was modified by the use of a 50mm hole saw and a section of 50mm OD aluminium tube offcut, suitably polished and lacquered. The appearance is enhanced and it makes fitting the tail ballast easier.


At this time, sand the fin to a symmetrical, airfoil shape.

FINAL ASSEMBLY...AT LAST


All components were covered in light tissue and dope before final assembly to seal all areas of the airframe. The tissue adds strength and fills the grain somewhat.
Battery, receiver, throttle and nosewheel servos site well back to counter balance nose weight Delstar is fully sheeted to maintain its profile and strength
Battery, receiver, throttle
and nosewheel servos site
well back to counter balance nose weight
Delstar is fully sheeted to maintain
its profile and strength

Remember to cut the ailerons free after the tissue is applied.


Using slow epoxy, glue the pod permanently into the wing. Glue the snake outers for the throttle and nose wheel steering to the pod inner with silicon sealant.

Fuselage, fin and wing fences are attached with aliphatic and tacked into position with CA. Using CA hinges, elevons may be fitted at this point.

Major wing fillets, manufactured from balsa triangle stock, are attached and epoxy/micro-balloon slurry fills the gaps.

FINISHING


The Batman scheme chosen for the Delstar complements the airframe and makes it look like it's doing 1000kts!
Experience shows that no matter how radio active the paint or film on the underside of an aircraft is, it always looks dull. It pays to have a dark scheme under your bird, with a contrasting bright colour on the upper surfaces.
Sand the entire airframe to an acceptable finish.

Apply several coats of thinned dope, sanding between coats to seal against the dreaded oil and to improve the finish.


Give it two coats of primer and a light rub down with 240 paper before masking and painting the scheme of your choice.
Let the paint fully cure then trim the canopy and attach.
Fit the tank, Rx, and flight pack, making sure the Rx and fight pack are as rear mounted as possible in order to minimise the ballast added to balance the powerplant.

CG


Balance aircraft to the point indicated on the plan, some ballast may have to be adjusted to obtain zero pitch trim, (ie. the AC flies straight and level with the trims in the neutral position. DO NOT go any further past this point, as instability will result).

MAIDEN FLIGHT


I love a 'maiden', especially when it is a scratch built, or plan built prototype. All those months of effort, the hours of checking and double-checking, the unmetioned doubts despite best efforts, (the trembling knees I love most of all).
The asphalt jet strip at AMA Monato has quite a lot of camber, but the wide track undercarriage of the Delstar tracked straight and true with little deviation. The nose wheel steering easily corrected the slight wander during take-off roll.
After sufficient speed had built up a moderate amount of up elevator was applied to  rotate to flying attitude and the Delstar rose skyward.

Adding a large amount of up-trim after take-off seemed to indicate a forward CG condition. This was confirmed when the engine cut some 60 seconds later (expect Mr Murphy to be your co-pilot on a maiden flight) and full up elevator was applied to maintain level flight. Somehow a safe landing was made and, after the test pilot had settled his nerves, and with more ballast added to the tail, subsequent flights were achieved with success and acclaim from the spectators.
Conditions had also improved now the maiden had been achieved and the Delstar flew 'hands-off' and with no trim deflection spoiling the slipstream.

As mentioned earlier, the approach for landing is like the approach for parallel parking. A good start leads to an acceptable result. Line-up is critical as any lateral adjustment will cost height. You can't sideslip without a rudder, so add power and go around, or she'll float off the end of the strip trying to slow down and stop. The Delstar has a remarkably good glide ratio and it certainly came in handy when the Magnum flamed out on the 'maiden'.

SUMMARY


The Delstar is an impressive Delta model that requires a 'hands on' approach to flying. It has remarkable manouvrability and a very wide speed range with safe handling characteristics even at low speeds.
 
SPECIFICATIONS
Delstar
Delta sports model
Wingspan 1.3 m
Length 1.2 m
Engine .46 - .60
Radio 3 channel r/c
 

DELSTAR  plans are available from:

To order a plan via e-mail

Airborne Plans Service
P.O. Box 30 Tullamarine Vic., 3043
Cost:  $33.00  plus $2.00 postage
Plan No. 667
 Credit Card Orders: Phone: (03) 9333 5100
 Fax: (03) 9333 5099

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