Micro-Hotliner Custom Build
Objectives
- design and build a 3mm Depron model
- able to fly in very confined outdoor space (slow and unbreakable)
- small/tough enough to put in the car for a picnic
- light/slow enough not to injure anyone if hit in an uninsured park
- streamlined enough to enable high scale-speeds
- use relatively standard motor, battery, servos, ESC
- also useful for slope-soaring with a small high-pitched prop or folding prop
Questions
- test depron with superglue (some claim that it works OK), whiteglue, and UHU por
- will normal packing tape stick to depron surface? iron on?
- 3mm CF tube not robust enough for fuselage? dope skin would help? buy better (heavier?) one from WiredRC?
- will CF fuselage be able to be drilled for pushrod entry/exit
- will I need a rear wing pad/hook for bands, so that wing doesn't get crushed by chord-wise band tension?
- do I need this just to get a rear mounting point for a more generous pod length?
Build Log
- weight of electronics (motor, ESC, battery, 2xservo+h/w, receiver) ~38g (34g budgeted)
Current Design
- 600mm wingspan, 70g AUW (14.5kph/4.0m/s stall speed), 100g thrust, 10min flight time.
wing
- 100mm chord including inset ailerons (aspect ratio 6:1)
- Depron fold-over (Clark Y) airfoil
- ailerons are cut from wing after construction (straight section of wing only)
- not removable
- contains aileron and elevator servos
- contains ESC and RX in leading edge cavity
- 2.5 x 20mm depron strip inside airfoil base with 3mm CF spar glued at Clark-Y max thickness - creates a "rib" effect with 3 points of contact and fills the inner ends of the cut-out ailerons
- blunt LE (3 bending "scores" 3mm apart) - higher lift as well as lower-speed and gentler stall characteristics
- ailerons extend to fuselage tube for some slow-flight/3D manoevering
- I-beam spar of Depron to create 12% thickness for Clark-Y airfoil, tapers after end of CF spar to allow curved tips
- no dihedral, but 10cm of each tip (beyond CF spar) curved up 2.5cm for low speed stability
- use lots of heat to curve whole airfoil, or score/kink/slice-reglue top surface, or taper wing to single 3mm layer wingtip and curve this
- packing tape on LE straight section for dent protection (from original bend?), FG strand around tip
tail
- 3mm flat Depron with rounded LE,
- fin extends below stabiliser to act as a skid to protect tailplane on landing, and to act as additional fin area and to allow more accurate rolls around CF fuselage
fuselage
- 3mm CF tube
- also acts as pushrod guide with smallest possible entry slot drilled and bound/glued for strength
- depron pod - square swamp buggy shaped, extends from motor to rear of wing - (streamline and protect electronics, holds prop off ground on landing, launch handle)
- attached by bound CF cross sticks - protrudes through sides of pod for rubber bands to hook onto
- wing cradle/seal formed by pod's raised upper surface just high enough to seal against wing.
- packing tape on bottom curve (all of pod?) to strengthen and as a landing wear surface
- 3mm CF tube
motor mount
- motor screwed to triangular ply plate,
- 3 triangles of depron webbing to retain on CF fuse
weights and specs
airframe (30g)
- 3mm Depron wing and tail - 15g
- wing CF 3mm x 400mm tube - 5g
- fuselage CF 3mm tube - 5g
- fuselage depron and misc - 5g
electronics (34g)
- 2 x 2.5g servos (BA-TS-25 20x10x22mm) - 5g
- motor (HK-AP05-3000 14x13mm, 5030 prop, 110g thrust) - 5.4g
- battery (2S 180mAh Z180-2S-15 40x21x9mm) - 15g
- RX (ORNG4 36x14x7mm) - 2.5g
- ESC (HK-SS10A 30x18x2mm) - 6g
other details
- bind cut-ends of CF fuselage tube to prevent fraying, CA around drilled openings
- control surfaces all tape hinged
- servos wrapped in masking tape and glued in (to allow retrieval for rebuilds)
- motor spec: Kv: 3000rpm/v, Lipo Range: 1~2S (3.7~7.4V), Suggested prop: 5030, Max current: 3A, Burst current (5sec): 4A, Weight: 5.4g (including mount and wire), Shaft: 1.5mm, Shaft length: 14mm, Dimensions : 14 x 13mm
- motor/prop test data: 5030 prop (Recommended), Voltage: 7V, Current: 2.8A, Thrust: 110g
pod or no pod
No pod ideas
- like adrenaline rush (external and stacked)
- receiver and ESC internal to LE of wing
- leaves large space for moving battery around or larger battery
- CF skid on front to protect motor and battery on landing
- loop of 1mm CF rod looped between holes on lower side of CF fuse
Pros
- could still add mini-pod later (to cover battery)
- lighter
- no problems with battery hatches etc
- quicker to build
Cons
- can't easily make wing removable (so can't try different wing formats)
- more drag than pod design (but this is low speed model)
- uglier than pod design
Use a podded design for a faster, more powerful version later.
rejected design
- ???provision for undercarriage (maybe for indoor flying if slow enough (second, big wing?))
- sliding motor mount
- balsa webbing to 4-5mm CF tube,
- tube slides onto 3mm fuse,
- rear of tube is split and clamped onto fuse with a cable tie,
- tie is tight enough to resist motor thrust and vibration but loose enough to slide on impact,
- depron packing at front of CF fuse adds shock absorption
- removable wing version
- wing covers battery access hole in top of pod
- mounting:
- wing centre has depron locator pads located chord-wise either side of where the CF fuse will touch
- wing depron pads at the spar sit on a ply plate (25x20mm) bound to bottom of CF fuse
- another ply plate sits internal to the wing, bound under the CF spar to spread the load over the two layers of 3mm depron between plates
- wing surface strengthening spars (1mm FG rod?) at centres of LE and airleron hinge line prevent edge damage from rubber bands and fuselage pressure
- CF or FG rod bound to top of fuse as rubber-band hooks
- above hooks and pod top-plate depron edge used as forward stop for wing
- rubber-bands stretch from one front hook, over wing, under aileron pushrod, under fuse tube, back under other pushrod, back to other front hook.
design ideas from
Adrenalin Rush (balsa 23.4", 69sq.in., 3.5-4oz) - http://www.rcgroups.com/forums/showthread.php?t=380270
- Alternative version - cross between Adrenalin Rush and Speed Stick below
- same size, but lighter, slower and more unbreakable (Depron)
2 x 5g servos, 14g motor (C1822/20 prop saver, >150g thrust), 32g battery (3S 360mAh), 4g RX (orange w/o case), 6g ESC (HK-SS10A) = 66g
- target airframe at 30g (AUW=~100g, 3.5oz) - note: this is higher wing loading than Stryker!
- lighter: 2 x 5g servos, 9g motor (1404N-2290 prop saver, 130g thrust), 21g battery (2S 350mAh Z350-2S-20), 4g RX (orange w/o case), 6g ESC (HK-SS10A) = 50g (allows for a 50g airframe)
- super-light: 2 x 2.5g servos (BA-TS-25), 5.4g motor (HK-AP05-3000, 110g thrust), 15g battery (2S 180mAh Z180-2S-15), 2.5g RX (ORNG4), 6g ESC (HK-SS10A) = 34g (allows for a 66g airframe)
Speed Stick (10") - http://www.rcgroups.com/forums/showthread.php?t=1118540
- especially 16" version (AUW=15g, page 6)
- HK Mini Swift R/C EPO Glider
http://www.hobbyking.com/hobbyking/store/uh_viewitem.asp?idproduct=11306
Spec: Length: 485mm, Wingspan: 610mm, Motor: Brushless outrunner, ESC: 6A, Prop: 5.1x3.1, Servo: 2x3.7g, 1x8g, Battery: 7.4V 2S 350 ~800mah 20C (Not Included)
buyer reported 120 grams with a 360mAh 2cell LiPo
- also has "turned up" wingtips as intended on mine
- GWS P-J3-S (high aspect ratio with boom)
http://www.championhobby.com/info.php?id=682&name=%20GWS%20P-J3-S
- similar form-factor, aspect ratio, and wing-loading as above design but scaled down to 2/3 size
Swifter (high-aspect ratio KF2 foam wing slope soarer) - http://www.rcgroups.com/forums/showthread.php?t=1222559#post14771215
Revert2 (same as above) - http://www.rcgroups.com/forums/showthread.php?t=682098
Gym-Blu (example of undercambered sheet foam wing) - http://www.eflightwiki.com/eflightwiki/index.php?title=Gym-Blu
Split-stick (similar to above, but more ideas on wing mounting) - http://www.rcgroups.com/forums/showthread.php?t=254490#post2413432
Gene Bond's designs (lots) - http://www.genebond.rchomepage.com/plans/ including a P51 - http://www.genebond.rchomepage.com/plans/Blu-51cd%20tiled.pdf
slightly bigger depron micro-hotliner - Wingspan:695mm, 146gr, 10g BL 2000kv, 3S Lipo 370mAh, 3x3,7g Servos, 6A Turnigy ESC, Controls: Throttle, Elevator, Rudder, Aile - http://www.youtube.com/watch?v=9oV8CR53Wu0
small depron and CF fuse slope soarer - http://www.rcgroups.com/forums/showthread.php?t=553166
Nutta depron and CF fuse slow flyer - http://www.flyelectric.ukgateway.net/indoor.htm#nutta
Alula with a depron pod - http://cmreel.com/?page_id=680
glider with CF fuse and idea for pod with CF through centre-line - http://www.rcgroups.com/forums/showthread.php?t=595238&page=3
Nano-Falcon glider (depron, CF, pod) - http://www.nanoplanes.net/nanofalcon-manual.pdf
Nano-glider (about right size, 70g with battery) - http://www.rcgroups.com/forums/showthread.php?t=547938