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Brock's BR-5 Mini-Goose

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durabol

Well-Known Member
Joined
Mar 2, 2010
Messages
169
Location
Lethbridge, Alberta / Canada
Sorry if this is a little disorganized. A English teacher once said I think of things in a "scatter-shot" method. :)
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-Low wing, single place, composite structure with some wood hard points (longerons, spar box). 18'x3.5', 7.3" thick, AR=5, Simple design that uses a rounded fuselage and a tapered wing. A wing stub is used for the retractable conventional landing gear (KR-2 like) and fuel tank. The 2 outer wing panels are easily removable and the plane can be towed. The outer panel spar inserts are long and slide into the wing stub spar/box and are pinned in place in the fuselage through the shear web. To simplify flaperon connects and landing gear a straight wing is used. Two spars (pultruded carbon caps) are used with a solid foam D-cell wrapped in fiberglass (the D-cell isn't so much for torsional stiffness but rather ease of construction as I don't have to make nose ribs and skins). The rest of the wing is a built up composite structure with foam ribs capped with fiberglass and wing skins. A T-tail is planned with a hollow fin, the other tail and control surfaces are solid foam wrapped in fiberglass. All control surfaces are balanced.
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-Weight Targets: fuselage 100, wing/wing fitting 150, engine/tank/prop 125, tail 40, controls 25 = 440 empty, 60-90hp, 5h range with 10-25gal(60-150lbs) at 2-5gal/h, 725-815 gross
-Performance: 45mph stall (slotted flaperons are used for a CL of 2.5), 62sq.ft wing area, 100mph cruise at 75% at a CL of .50, 120mph at 100% at a CL of .35 , 150mph at CL of .22 (if use larger engine)
-area=800lbs/(66.15^2*2.5*.5*.00237)=62sq.ft
-CL at cruise=800/(.5*.00237*147^2*62)=.50
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-For an airfoil I'm considering an AS5045 (designed for the KR-2S and has low drag and slightly less lift than the 23012), or a mildly laminar Riblett airfoil (likely). I would like to design an airfoil specifically for this plane with a computer program like X-foil but that's beyond my abilities for now. I will use an 18% thick airfoil for a lighter wing, to hide the retractable gear better and for more fuel storage.
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-hotwire easier than cutting out with band saw and sanding: D-cell, tail/control surfaces, slotted flaperon channel, Hoerner wing tips
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-For the retractable gear I would like to use pultruded carbon but I may end up using KR-2 parts.
-The wing spar and spar box are major engineering problems. I only know generally how much they should weigh.
-I have enough information for the flaperons, fuselage, tail and control surfaces and hinges, control stick/rudder pedals and linkages.
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Fuselage:
-wood longerons like Long-EZ for easier/safer structure
-roll over structure
-use fillets/fiberglass tape for bulkheads/nose of fuselage, rear of fuselage
-Quickie/Long-EZ: sides: one layer of BID over entire, 2nd layer from front to past cockpit, 3rd layer from front firewall to instrument panel, one layer of BID over entire outer fuselage, another layer from seatback bulk head forward, 1" minimum overlap
-PolliWagen: 2 layer of bid at 45d on interior and exterior
-plywood in fuselage side that wing stub spar box goes through
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Wing:
-20% thick wing for more fuel and gear retracts more?
-pultruded carbon fiber spar/tail spars
-for spar placed rods on side and build up layer to .5" and wrap in glass then wrap entire spar for shear web or glass/epoxy too brittle?
-not a lot of material so still flexibility problems, derated pultrusion to 150-175ksi and designing to 9G (Marske) or 12Gs or 18Gs (Orion)
-use wing stubs: flaperons that pin together for very easy connect/disconnect, fuel tank in wing stub
-solid foam D-cell LE (cut out foam for gear hinges) for easy construction/laminar flow
-outer panel spar slides into stub spar (hollow plywood/balsa reinforced with glass) pinned in place in fuselage, outer panel spar insert acts as core of stub spar for shear, low compressive force on outer panel insert since insert long
-go with straight wing, wing long so adequate rotational stability already, no binding with flaperons or longer landing gear needed
-bolt/pin that goes through shear web reinforce with bid
-folding wing adds 25-30lbs
-as high an AR and as short a wing stub as possible with enough room for fuel and retractable gear (dimensions of wheels)
-fuel tank close to fuselage with gear on outside, gear 6-8' wide, have 2-3' span of fuel storage; .10 and .65 spars so .55*2.75=1.375'cord, 15% thickness airfoil so height=2.75cord*.20=.55; tank volume=.55height * 1.375'cord * 2-3'span=1.5-2.3cu.ft=9.3-14.3gal
-1cu.ft=6.22imp.gal=7.5USgal
-solid foam wing: need box spar for removable wing panels which kind of defeats purpose, 22x2.73*.41*2pcf/2=about 20lbs foam
-single wing spar is located at .30 cord, double at .10 and .65
-1" rectangular box wrapped in glass glued to front/back spars to attach skin
-PolliWagen: wing panels made with 2 layers of glass on inside and out
-1" foam rib capped with 1.5" glass tape, 5oz, 2' rib spacing, closer spacing near root so can stand on wing and extra layers of glass (at least 3 layers)?
-flaperon: 25-33% cord=8.2-10.8"
-4 flaperon hinges: on inside of cockpit (torque tube goes through into fuselage), on outer part of wing spar in line with landing gear, 2 hinges on outer wing panel, reinforce on either side of spar and use bushing, copy/buy LEZ flaps/hinges: 20d up, 22d down 5d down aileron and 10d up, nut plate in Al torque tube?, solid foam structure aft of rear spar (cut out with hot-wire), high density foam inserts for flaperon hinges?
-mount flaperon hinge to ribs (beefed up with glass and bushing) in front of rear spar for close to .40 cord dropped 25d, differential ailerons 20up/5down (heavy controls so use center stick), large rudder to counter adverse yaw
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Landing Gear:
-hinges at sides in cockpit and outside of cockpit near wheel
-balsa/wood core pultruded carbon landing gear?
-secure retractable gear hinge to spar by wrapping around spar
-make gear on edge rather than flat with locking device that drops onto gear beam, enough flex in carbon fiber that gives some suspension even on edge
-make out of carbon or metal (buy castings): spring bar, wheel fittings, 4 hinges and 2 locking mechanisms
-rudder/sterable tail wheel with cables (Quickie, KR-2)
-hydraulic toe brakes (PolliWagen/Long-EZ)
Fuel System:
-fuel tank: one layer of bid on inside and 2 on outside
-nose tank gravity feed?
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Controls:
-center stick, side stick, side yoke
-flaperons with reflex setting for laminar airfoil/pitch trim
-control surfaces are solid foam with 1-2 layers of glass with LE Al torque tube
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Tail:
-T-tail
-built up hollow fin for stabilator push-rod to go through
-solid foam rudder/stab/elevator with aluminium tube LE easiest or built up with pultuded carbon (lighter)
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Canopy
-form own or buy pre-made?
-Plexiglas or lexan
-sliding or hinge at front|back|side
-latch/lock?

Brock
 
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