Eppi - SOAR

78in (2 metre) EPP Crash Resistant Thermal / Light Wind Slope Soarer

Designed by Stan Yeo

Produced by PHOENIX MODEL PRODUCTS

Introduction

The Eppi-SOAR is a stylish 78in span EEP crash resistant flat field thermal soarer / light wind slope soarer designed for the modeller wanting to combine EPP durability with rigid structure performance. Eppi-SOAR makes an excellent basic trainer as it will fly off the slope in the lightest of winds and yet still cope with the stronger winds when other more lightly built models have been put away. It can also been flown from a flat field using a Hi-Start or Bungee to get the model airborne. Eppi-SOAR is capable of a wide range of rudder elevator aerobatics such as loops, barrel rolls and inverted flight in good conditions off the slope. Spins are another of Eppi-SOAR's specialities, being easy to enter and easy to exit. As with all EPP models building time has been kept to a minimum, typically 8 -12 hrs depending on the skill and care taken. Field repairs if required are of the Elastoplast variety!

Tools / Materials Required

The only tools required are a modelling knife with spare blades, a pair of sharp scissors, soldering iron, 180 grade Wet & Dry sanding block, a can of impact spray adhesive such as Stikatak, some runny super glue (please observe safety precautions on packets!), epoxy and a soldering iron.

R/C Equipment

The R/C Equipment used in the prototypes consisted of two standard size servos (HS300) for the rudder and elevator, a standard AA size Rx battery and a 4/5 channel receiver (Hitec / GWS). All the items are available from PMP at competitive prices.

Building the Fuselage

1. Lightly sand the fuselage sides, top and bottom with 180 grade wet and dry to remove the 'release' agent. Remove dust with a small brush or vacuum cleaner.
2. Drill wing dowel holes in fuselage sides and fit fuselage nose & tail doublers using spray impact adhesive
3. Fit distance pieces and nose former to one fuselage side. 3. Using thin superglue fit 4.5mm sq. strip, tail post and triangular nose strip to fuselage. Check you have a left and right side!
4. Join fuselage sides together over plan ensuring fuselage is straight. Cut nose top to length and fit.
5. Cut fuselage top to length and glue in position.
6. Fit elevator and rudder servos to balsa bearers and determine which side of servo the elevator pushrod needs to be for the elevator to operate in the correct sense! Position servos inside fuselage (Do not glue).
7. Drill holes for the elevator control rod in fuselage sides 120mm forward of the back of fuselage (see plan). Shamfer side of holes to reduce control rod exit angles. Note: It is important that the control rods are kept as straight as possible to avoid binding. If they do bind replace with 20swg piano wire and stiffen with off-cut at exit. Clean with white spirit.
8. Fit fuselage top and tailplane seat. Drill hole for rudder control rod just in front of tailplane seat. Reduce exit angle as much as possible to reduce control rod binding.
9. Fit control cable outers (with inners inserted) and attach to fuselage sides using CW Tape or balsa blocks. Watch for control rod binding.
10. Fit fuselage bottom and trim to length. Reinforce corner joints with 25 mm wide strips of CW Tape.
11. Spray the fuselage and EPP sides with spray adhesive. Hold nozzle 40-50 mm from work when spraying so that solvent does not have time to evaporate before adhesive contacts works.
12. Allow a few minutes for solvent to evaporate. Fit EPP sides and trim flush with top and bottom of ply box. Do NOT trim in front of nose former, this area will form a cavity later to house the nose weight. The EPP is best trimmed using s long bladed (X-Acto or similar) knife using the fuselage top & bottom as a guide.
13. Cut hinges in Fin and tailplane. Mark centre-line of tailplane and fit Fin using 10mm triangular strips of balsa either side of fin base.
14. Fit tailplane assembly using spray adhesive. Ensure that it is square.
15. Fit the EPP fuselage bottom as before and trim the EPP again using fuselage side as knife guide.
16. Fit EPP fuselage top (Front & Back). Relieve top underside around Fin base to accommodate triangular balsa strips. Round fuselage corners.
17. Glue 120 grams or 4 ozs. of lead to front of nose former in cavity formed by EPP sides. Fit nose block and shape fuselage i.e. round corners using sharp knife and 180 grade wet & Dry (use dry!).
18. Make hatch, shape and cover with CW tape.
19. Cover fuselage with CW tape (lengthwise). Lay first strips along fuselage sides aligned with bottom of tailplane. Overlap each strip by 6 - 10 mm or 1/4 to 318 inch. In high stress areas such the under the wing leading and trailing edges apply an extra layer of tape for added strength. Cover CW tape with coloured vinyl to decorate model and protect CW tape from the effects Ultra Violet light.

Building the Wings.

The only UK manufacturer of EPP, suitable for modelling, has ceased trading and we are currently not aware of another UK / EU source. To maintain production of our EPP kits we stockpiled the material before they closed down. Unfortunately some of it is of variable quality and some wings cut using our two CNC machines have more than the usual amount of surface blemishes. We apologise for this and assure you that ALL wings are individually check before packing to ensure that the blemishes will not have an adverse effect on the performance of the model.

1. Lightly sand wing surfaces and remove dust as before. Remove waste from wing brace slots.
2. Fit 1mm plastic trailing edge reinforcing strips using spray adhesive. Coat both surfaces and allow solvent to evaporate before sticking together.
3. Laminate 4off 1.5mm ply centre braces using Superglue. Epoxy wing wing main spar and epoxy wing joiner tubes in position.
4. Laminate 2 x 1.5mm wing tip spars as before.
5. Join wing-halves to main spars using epoxy. Place on a flat surface. Use masking tape and books to hold wing in position / together while epoxy sets. Take care to keep spar slot clean of epoxy where tip panel spars are attached to centre panel main-spar.
6. Join tip panels to centre panel ensuring the tip panel is at the correct dihedral angle. Note leading edges should form a straight line i.e. not be swept back or forward. Shape wing tips.
7. Drill holes in ply end ribs to accept wing joiner / hardwood dowel wing locating lugs. Epoxy ribs in position. Hold in place with masking tape whilst epoxy sets.
8. Spray wing with spray adhesive and cover wing with GW tape. Start by laying strip along TE. Then work forward overlapping the previous strip by 6-10mm. At the leading edge trim tape as you would if covering in film but overlapping top and bottom by 10mm. Cover top surface of wing with coloured vinyl tape I lightweight Fablon or iron on film. This serves two purposes, one to decorate model, the second to reduce the effects of ultra violet light on the CW tape.
9. Using scrap wing sleeving manufacture wing fairing, cover and double side tape to one wing panel.

Flying

1. Set the controls to give the following movements for initial flights: Elevators +/- 8 mm Rudder +/- 25 mm Balance Point 70mm +/- 5mm from LE. Prototypes required 120 - 150 grams (4 to 5 ozs) nose weight.
2. Laterally balance wing and check that it is not twisted. If the wing is twisted, twist back in the required direction and re-smooth covering tape in position with a warm iron.
3. If you are new to the hobby and inexperienced it is strongly recommended that you make contact with an experienced modeller to trim the model and give you some basic flying instruction. It is also strongly recommended that you take out third party insurance. This can be arranged by telephone through the BMFA (British Model Flying Association) on 0116 2440028.
4. With Rudder Elevator only control the model does not respond instantly to a control input. This means that any manoeuvre must be planned in advanced. Also when the model starts to respond to the control input the rudder control must be slowly returned towards the neutral to prevent the turn becoming a spiral dive. If you want the model to turn tightly then up elevator must be used to keep the fuselage level (see Prepare to Survive article on our website phoenixmp.com).
5. If using a hi-start or bungee to launch the model use either 6mm (1/4 inch) square catapult elastic or 8mm dia. surgical tube. The minimum length should be 30 metres with at least 4 times the bungee's length of 25 - 30 kg (65lb) breaking strain mono-filament nylon fishing line attached along with a parachute to keep the line straight as it falls to the ground after the launch. Initially the bungee or hi-start is tensioned to at least 2 times the length of the rubber. When launching the model hold it at a 30 degree angle give it a solid push when letting go to assist the bungee accelerate the model to flying speed. Do not pull in up elevator at this stage as it will cause the model to stall off the line with disastrous results. If the model fails to climb i.e. gets pulled along by the bungee with its nose in the air, put the nose down (apply down elevator) to regain flying speed, this will release the model from the bungee, and land straight ahead. It is unlikely that you will have enough height to perform a 360 degree turn. Try again but this time with more tension on the bungee. Once you have got the model climbing satisfactorily try feeding in a little up elevator on the climb. If the model shows sign of not climbing or wandering on the line release the up elevator. If the model in light to modest winds lifts a more than 20-30% of the rubber of the ground then increase the length of nylon line. Lifting the rubber of the ground reduces the launch height.
6. When performing aerobatics remember that the model requires energy to perform them. If the model has insufficient speed it will fall out of the manoeuvre or perform it half-heartedly. Vertical or near vertical dives are not an efficient way to build up speed, 20 - 30 degree dives are much more efficient. Avoid sudden control inputs. In most cases all they do is scrub off speed and lose height. Try to fly smoothly with the minimum of control input as not only do the manoeuvres look better but you will be able to perform more of them before having to regain height. Try stringing manoeuvres together paying particular attention to positioning. Be creative and set yourself targets for each flying session.
7. If you are having difficulty penetrating into wind try ballasting the model about the balance point. Avoid over-ballasting as this will degrade performance and make the model more difficult to fly.
8. Eppi-SOAR will take a lot of punishment. It is excellent for building confidence and will add another dimension to your flying but please remember if you take a big enough hammer to anything it will break. The CW tape used for covering also degrades in ultra-violet light so store the model in a relatively cool place away from direct sunlight and do not rest anything against the Correx tail.
9. Finally should you require further assistance or advice please contact us either by letter, telephone, email or visit our website (http://www.phoenixmp.com) where you will find useful information on sloping etc.

Happy flying

Stan Yeo

Eppi-SOAR 020723