Hoodlum

Crash Resistant 60in EPP Pylon Racer / Sports Aerobatic Slope Soarer

Designed by Stan Yeo Produced by PHOENIX MODEL PRODUCTS

Introduction

The Hoodlum is a flying wing with a difference. The ailerons and elevator do not share control surfaces and consequently do not require a control mixer but if you do own a computerised transmitter there are a number of additional control options available such as Crow Braking to aid landing in tight areas or when flying with full ballast. Also the elevator can still be coupled with the ailerons to improve performance in 'looping' manoeuvres (inside and out). With a separate elevator, control response is more progressive. This is accompanied by a small reduction in induced drag at the wing tips. Like other models in the series the Hoodlum is capable of a wide range of aerobatic manoeuvres including inside and outside loops, horizontal eights (like a Cuban Eight without the half roll in the middle), continuous inverted flight and several consequetive rolls not to mention a very good turn of speed with or without ballast. There is provision to carry up to 12ozs (340 grams) of lead in wing mounted ballast boxes to give added bite in strong winds and trade excess lift for speed. As with all EPP models, building time has been kept to a minimum; typically a quarter to a third that of an equivalent wood foam model depending on the skill and care taken.

Tools / Materials Required

The only tools required are a modelling knife and spare blades, 180 grade Wet & Dry sanding block, a set square, soldering iron and a hand drill with a 5mm bit. Glues etc. required are spray impact adhesive (Stikatak), runny super glue, 12 minute epoxy and Sellotape Diamond plus 'top covering'. Please observe safety precautions for the glues!

R/C Equipment

The R/C equipment used in the prototypes consisted of three metal gear micro servos (HS81MG /85MG/ Futaba S3150) a AAA size square Rx battery pack plus a JR R700 / Align 6 / Futaba 147F / Hitec Slimline Rx along with a switch harness and two servo extension leads. 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. Mark position of 4.5mm distance pieces (2 off) to fuselage sides ensuring you have a left and right side!
3. Superglue 4.5mm sq. strip and triangular nose strips to fuselage sides (not shown in picture below - error!).
4. Superglue wing seats in position.
   
5. Superglue nose former (B1) and the other two 4.5mm distance pieces (B2/3) to one fuselage side ensuring they are all perpendicular (use set square) Check dowel former can be slid in position.
6. Fit balsa block at rear of fuselage.
7. Join fuselage sides together over plan checking that the fuselage sides are correctly aligned using a set square.
8. Cut 1.5mm fuselage top to length and superglue in position.
9. Repeat Step 9 above for fuselage front bottom front allowing for wing dowel plate.
10. Fit 1.5mm ply bottom to rear of fuselage.
11. Cut / Sand ply top and bottom to size.
12. Fit switch harness to top of fuselage. Take care not to mount the switch to far forward so the it interferes with fitting the Rx battery and receiver. Remove switch after fitting.
13. BUILD WING
14. Construct Wing Nut block assembly as per plan. Slide into and hold in place and hold in position using scrap foam rubber. Slide into position the 6mm ply Wing Dowel plate.
15. Fit the wing to the fuselage and mark position of wing dowel hole on dowel plate. Tip - wet end of dowel tube with felt tip pen to leave impression on dowel plate. Ensure dowel hole is in middle of dowel plate and drill dowel hole.
16. Superglue dowel former in position. If necessary, slide former 'in & out' or rotate back to front as necessary to compensate for any inaccuracies in drilling dowel hole.
17. Fit triangular strip to front of former (see plan).
18. Fit wing to fuselage and locate position of wing nut assembly.
19. Glue nut assembly in position.
20. Glue EPP sheets to fuselage sides using spray adhesive (spray both surfaces). Allow a couple of minutes for solvent in adhesive to evaporate before fitting EPP to fuselage. Allow the EPP to extend past the nose former by at least 12mm (see plan). Also remember this is a ONE shot operation!
21. Trim the EPP to shape of fuselage using White Spirit to lubricate knife. The best tool for this operation is one made from a broken piece of hacksaw blade approximately a 75mm long. Grind the teeth off without getting the blade so hot that it loses its temper and goes soft. Sharpen blade on a whetstone or oilstone so that you could almost shave with it! The advantage of this blade over commercial blades is that it is flexible allowing the 'handle' to be bent out of the way when cutting the EPP to achieve an acute cutting angle.
22. Glue 8mm thick EPP to fuselage top aligning Fin slot in EPP with Fin slot in fuselage again extending beyond nose former as per Step 20.
23. Glue 8mm thick strip of EPP to fuselage bottom at nose. Extending beyond nose former.
24. Glue approximately 90grams of roofing lead to front of nose former in cavity formed by EPP sides. This is typically 2mm thick and equates to 5/6 layers of lead. Flatten lead before fitting. DO NOT GLUE. Roofing lead is available from a scrap yard at reasonable cost. Trim EPP in front of nose weight to provide flat surface on which to glue EPP nose-block.
25. Fit nose block and shape fuselage i.e. round corners using sharp knife and 180 grade wet & Dry (use dry!).
26. Because the wing mounted ballast boxes are forward of the Balance Point adding ballast moves the balance point forward. To compensate for this some of the nose weight is removed. This requires a small hatch underneath the nose weight. Remove a rectangular piece of EPP and replace it with balsa block. Shape balsa insert.
27. Cover fuselage using CW tape. Overlap each strip by 6 - 10 mm or 1/4 to 3/8 inch. Use Film Iron to remove wrinkles around compound curves. Temperature required for this operation is fairly critical. Do not dwell in one spot too long to avoid damage to the foam. Use white spirit to lubricate cutting knife. Fit 6mm square strip to base of Fin at front.
28. Top cover the fuselage with either coloured vinyl tape or an iron-on film such as Profilm (highly recommended).

Building the Wings.

1. Lightly sand wing surfaces and remove dust as before. Trim and sand spar slots to accommodate mainspars. This is best achieved using a very sharp knife and a spar length straight edge (Tip - stick 180 grade wet & Dry to under surface for grip) plus a short length of 10mm thick ply fitted with Wet & Dry along one edge for final sanding of spar slot. Unfortunately CNC cutting tapered wings with spar slots results in a tapered spar slots due to the way CNC cutters work.
2. Tip - When adjusting spar slots tape a straight edge to trailing edge of wing to ensure TE remains straight.
3. Remove waste from wing bracing slots.
4. Fit top wing spars (the thick ones) using Epoxy keeping spar bracing slots free of Epoxy. Place packing tape along spars, place wing on a flat surface. Hold flat with weights until epoxy set.
5. Repeat Step 4 for bottom spars.
6. Trim spars to length.
   
7. BUILD BALLAST BOXES
8. Fit 6mm sq trailing edges using epoxy again keeping bracing slots free of epoxy. Use masking tape to hold spar in position whilst Epoxy sets. Trim to length.
9. Dry assemble wing to check that wing roots mate with a straight trailing edge. Adjust as necessary.
10. With wing upside down fit wing brace. Note once again the trailing edge should form a straight line i.e. not be swept back or forward.
11. Fit rear spar brace and trim to size when epoxy set.
12. Fit rear wing brace using epoxy.
13. Manufacture Elevons and wing centre by laminating 0.8mm ply and balsa trailing using spray impact adhesive. Place under weight until adhesive has properly set.
14. Glue centre section to wing observing wing reflex (apparent up elevator). Refer to wing seat on fuselage.
15. Fit 0.8mm ply ends to centre section and one end of each Elevon.
16. Sand wing tips to shape and trim Elevons to size. Sand to shape.
17. Epoxy balsa block in position at wing join. Bottom of block should be flush with bottom surface of wing.
18. Trim top surface of block to shape of top surface of wing. DO NOT trim bottom of block.
19. Locate centre of balsa block and centre of wing leading edge. Drill hole for 5mm diameter brass tube the houses 4.5mm diameter hardwood wing locating dowel.
20. Epoxy wing dowel tube in place. Mark centre of tube hole on 6mm ply dowel locater in fuselage. Use felt tip pen to assist in this.
21. Manufacture a long drill using 4.5mm diameter piano and drill dowel hole in 6mm ply.
22. Drill hole for M5 wing bolt in wing and ply bolt plate. Do not drill through rear spar!
23. Fit 1.5mm ply wing bolt reinforcing plate using superglue.
24. Shape wing tips.
25. Mark position of wing servos (plan drawing is NOT full size. Position of servo is dependant on servo lead length. Allow 30mm from end of plug to servo lead exit from wing for connecting to receiver extension lead when fitting wing. Note servo arms both point outboard of wing.
26. Cut rectangular hole for servo in wing ignoring servo mounting lugs.
27. Cut slot in EPP for servo lugs and fit servo so that it is flush with top of wing. Note gap between top of servo and bottom of wing. From block of EPP removed for servo from wing slice off the required amount and fit in this void.
28. Centre servos (see Prepare to Flap article on website) and rotate output arm so it is flat to the wing in preparation for covering wing. Cover servo with masking tape.
29. FIT FIN MOUNTING BLOCKS.
30. Spray wing with spray adhesive and cover wing with CW tape. For torsional rigidity cover the wing with CW tape diagonally. There is no need to wrap around rear spar but do overlap by 5 - 10mm at leading edge. For smooth finish do not overlap CW Tape. Use film iron to remove wrinkles at tips.
31. After covering fit aileron servos. Cut vertical slot in wing to hide servo leads.
32. Cover wing with either coloured vinyl tape or an iron on polyester film (NOT polypropylene it stretches!). This is necessary for two reasons, one to decorate the model and secondly to protect the CW Tape from the effects of ultra violet light. If film covering roughen surface of CW Tape and lightly spray with impact adhesive.
33. Cover control surfaces in an iron on film in chosen colour. DO NOT use CW or vinyl tape.
34. Hinge control surfaces using Sellotape Diamond as shown on the plan.
35. Fit control linkages and adjust to obtain required throws (see flying section).
36. Unless you are flying in high risk mid-air situations DO NOT replace the plastic mini-snaplinks with metal devises as in the event of a mishap the plastic snaplinks will break thereby reducing the risk of damage to the aileron servos.

Building Ballast Boxes

1. Remove foam from ballast box cut-out from wing.
2. Construct a distance piece that will hold the ballast box sides in place whilst the glue sets. Again it should be a snug fit and not a force fit. Cover in Sellotape / cling film to prevent it sticking to box sides during assembly.
3. Cut 1.5mm ply sides to size and number them.
4. Using the distance pieces glue ballast box sides to wing.
   
5. Superglue balsa ends and top in position. Sand to shape.
6. Fit ply hatches. Adjust distance pieces so that when covering the wing the hatch cannot drop down into the ballast box.

Fitting Fin Mounting Blocks

1. From the wing join at wing root measure 200mm outwards towards wing tip on both wings.
2. Using set square draw a line at right angles to rear spar across the wing. This is the centre of the Fin.
3. Cut rectangular holes thro' the wing the same size as the 16mm square balsa Fin Mounting Blocks aligning the centre of the block with the centre line of the Fin.
4. Epoxy the above blocks in position and sand to the wing contour. Note the grain should be vertical.
5. With the aid of the set square mark the centre of the mounting blocks and drill VERTICAL holes the same size as the 4 mm plastic tube used to house the 12 gauge wire to secure the Fin. DO NOT to glue the wire in position.
6. Depending on how secure the plastic tube is in the mounting blocks will depend on whether you glue them in using Superglue or 2 part Epoxy.
   
7. Using a sharp pointed rod of the same or slightly smaller diameter poke holes in the base of the Correx Fin to accommodate the 12g mounting rods.
8. Remove the Fins and 12g rods for covering the wing.

Flying

To achieve the design performance of any model care must be taken in setting up the controls and balancing the model both laterally (wing tip to wing tip) and longitudinally (nose to tail). The Hoodlum is no exception. Control movement must be symmetrical i.e. the same for both Elevons.

Set the controls to give the following movements for initial flights:

Ailerons +/-18mm Elevator +/-15mm

Elevator (Ailerons) +/-5mm

Reflex align controls surfaces with base of Fin

Balance Point 75mm +/- 3mm from LE at back of dowel former.

1. Adjust balance point to within recommended limits. This can be done by taping a hexagonal shaped pencil along the bottom of the wing at the balance point and resting the model on a flat surface. Prototypes required a small amount of additional nose-weight to that fitted in the nose.
2. For competition flying i.e. 60in EPP pylon racing, a slightly rearward balance point was found to be the optimum. It is recommended that initial flights are carried out at the mid balance point and adjusted to suit your style of flying. See Item 9.
3. Check than Fin is perpendicular to wing. Adjust wing seat as necessary.
4. Launching the Hoodlum is easy. Place the thumb and second finger either side of the fuselage just in front of the wing leading edge. The forefinger is placed on the underside of the wing. This is important as the forefinger ensures the model is launched in a level attitude and stops you pulling the nose down and launching the model into the ground! The transmitter is naturally held in the free hand.
5. Remember all aerobatic manoeuvres require 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. Hence the need for progressive elevator movement. Avoid sudden control inputs. In most cases all they do is scrub off speed and lose height but they could also result in a violent 'flick' roll. 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.
6. If the lift is very good or you are having difficulty penetrating into wind try ballasting the model. This will increase penetration and help the model maintain speed through manoeuvres. Note when adding ballast it will be necessary to remove some of the nose weight (using the hatch) to counteract the effect the effect of the ballast moving the balance point forward.
7. We have found the optimum ballast to be about 200 grams. Over-ballasting any model will lead to a degradation in performance, often accompanied by a tendency to tip stall if flown too slowly or the elevator is used zealously.
8. The suggested control settings are a starting point and can be adjusted to suit your personal tastes. An indication that the balance point is about right can be gauged by the amount of down elevator required for smooth inverted flight and how the model recovers naturally from a dive i.e. sticks in neutral and no pilot input.
9. If you are using a computerised transmitter program in positive (JR) Exponential on the Aileron and Elevator controls. This will 'soften' the controls around the neutral position and facilitate smoother flying particularly on the elevator control.
10. Hoodlum 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.
11. The MH64 wing section is very efficient and performs well in light lift so with good ballast selection Hoodlum will cope with almost any wind / lift conditions you are prepared to fly in.
12. 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.

Hoodlum Design Features

1. It uses the highly efficient MH64 wing section.
2. It has a slim, EPP clad, ply box fuselage. Not only is the fuselage extremely strong but it has considerably less volume than many of its contemporaries. Fuselage volume has a large impact on a model's performance. The more air that is displaced the higher the drag!
3. The Hoodlum is a two piece model with detachable fins. The wing is attached to the fuselage via an easily replaceable M5 nylon bolt and a 5mm hardwood dowel (housed in a brass tube). These are designed to shear in the event of a 'mishap thereby minimising any resultant damage.
4. The hardwood mainspars extend all the way to the wing tip. This not only stiffens the outboard section of the wing but offers protection to the control surfaces should the model land on a wing tip.
5. The top spar is thicker than the bottom spar. This significantly strengthens the wing as most wing failures in flight are due to the top surface failing in compression.
6. The thin balsa control surfaces are laminated with 0.8mm ply to add stiffness and make them more 'ding' proof a feature not normally seen on the type of model.
7. The easily accessible, inbuilt ballast boxes, allow quick change of ballast between flights to take advantage of changing flight conditions.

Happy flying

Stan Yeo

Hoodlum 060108