Hints For Homebuilders

integral axle, so I drilled and tapped the tailwheel assembly at the end op- ... help you decide what type of airplane you d enjoy building, and we'll give you the ...
1MB taille 3 téléchargements 338 vues
LANDING GEAR INDICATOR SYSTEM The schematic included with this Hint is for a retractable landing gear indicator system. When the gear switch is activated, 5V power is switched from one set of indicators to the other, in parallel to the motor output. For example, as the switch is moved from DOWN to UP, the DOWN indicators will go out, and the UP indicators will start flashing. The indicators will continue to flash until the gear completes the cycle, at which time the NC (normally closed) side of the microswitch is opened and the NO (normally open) side closes. At this time, the indicator LED will glow steadily. Only half of the display (gear up or gear down) is illuminated at any time. This gives an indication

of which way it is moving. cuits (UP and DOWN) is used for each If any of the individual gear legs gear leg. A complete system of up and fails to fully extend or retract, the cor- down indicators can be fed from a sinresponding light will continue to flash, gle voltage regulator as shown. I while the others glow steadily. This would suggest putting a heat sink on will alert the pilot to the problem.

20 AWG wire would be sufficient for all connections. The circuits shown use identical components and vary only in the 470 ohm resistor shown in the lower ones. The purpose of the additional resistor is to reduce steady state brightness. You could try using the circuit with only 330 ohms first, and add the 470 ohm resistors later if the indicators were too bright at night. Experiment with other values until you find a suitable brightness. Use 1/2 watt resistors. One pair of cir-

LG INDICATORS CHERRY DC2C-A1RB (NEWARK 95F9730) OR RADIO SHACK 275-017

RADIO SHACK 276-041

it. The flashing LEDs are not part of the display, but are used to interrupt the current. They and the resistors may be mounted anywhere convenient. On my plane, I soldered them directly to the switch lugs. Be sure to protect the leads against stress and vibration by clamping the circuit wires near the switches. Potting the assembly in epoxy mixed with a bit of milled glass is an additional precaution, and would also guard against corrosion. Cover the switch sides with duct tape and use additional tape around the components and base of the switch to contain the mixture. Cover the flasher diode leads, but leave the body exposed. Remove the tape after the epoxy sets. The 5v output from the 7805 voltage regulator and the leads to each set of indicators are connected to a separate pole of the landing gear switch, so that they are switched in parallel to the actuator circuit. I have shown Radio Shack parts because of their availability; but other sources and colors of LEDs could be used, although resistor values might change. I prefer the Cherry microswitch, which is water-

and dustproof, and rated at 10 amps. Newark Electronics (1-800/773-5250) currently sells them for

$5.98. They also have a huge catalog which is free

RADIO SHACK 276-1770

for the asking.

(7805 VOLT REG)

(This electrical hint was submitted by Williams

AIRCRAFT

14 OR 28V FLASH ^

Wade, EAA 358935, 2692 Town Farm Rd., Unity, ME 04988.)

90 MARCH 1995

NEEDED: COMPACT TOWBAR I wanted a lightweight, compact towbar for my RV-6 that I could carry onboard. This one requires no welding, only weighs one pound, is

flat bar stock with a hole drilled to accommodate the head of the axle nut. In my case I have a tailwheel with an integral axle, so I drilled and tapped

28 inches long (45 in. extended), and is simple.

the tailwheel assembly at the end opposite the nut for a pin made from a

nut. At the other end of the block is a

on the nut end of the axle, then

It's made from a hardwood block, drilled for the handle and for a short piece of PVC pipe with an elbow on one end. The plastic doesn't mar and the I.D. is easily varied with PVC pipe or reducers to just slip over the axle length of 1/8 x 1-1/2 inch aluminum

stainless 5/16 inch bolt with the head cut off. The U, formed by the PVC pipe and relatively thin aluminum bar, is flexible enough that installation is done by first putting the PVC elbow

snapping the bar end (left side in

Wondering If You Could Build One? Sure You Can! Learn How at the

Alexander Aeroplane Builders' Workshops intensive days of learning practical skills and Thelpwo techniques in the area of study you choose. We'll you decide what type of airplane you d enjoy

Sponsored by the EAA

building, and we'll give you the confidence to stick with it all the way through to that first fabulous flight.

and Alexander Aeroplane

Sample the skills you'll need to build or restore an airplane. Find out which type of structure appeals to you.

Coming Soon to a City Near You!

Beginners' Course - $149.

Intermediate Courses - $199 Each.

Choose one of these four basic skills courses: • Fabric Covering. You'll get real hands-on, how-to experience, covering and preparing a real wing. • Composite Basics. Explore resins, core materials, hot-wire cutting, shaping, finishing, and lots more. • Sheet Metal. How to correctly cut, bend, shape, and rivet all types of sheet metal. Excellent basics. • Welding. A practical primer in gas welding. You'll learn how to make a good, safe, sound weld. Free One-Year EAA Membership Included!

Reservations & Information

800-831-2949

LEXANDER EROPLANE COMPANY, INC.

Box 909, Griffin, Georgia 30224

SPORT AVIATION 91

4440 Southeast Blvd. Wichita, Kansas 67210

photo) on. It stays clamped on the axle under any hand towing load I've exposed it to. The handle is made from 2 telescoping lengths of aluminum tube, with a hitch in to hold it extended. The extra holes in the hardwood block are for lightening, and also balance the assembly so it does not rotate in your hand. This towbar is so cheap and easy to make that I made another for use around the hangar. That one has a fixed length of electrical conduit for a handle. They both work like a charm.

(Hint submitted by Bob Brumwell, EAA 160486,

INSTRUMENT OVERHAULS All prices include the normal replacement parts. You will be contacted if other charges are incurred. One year no hassle warranty. Gyro Horizon 3 Inch vacuum....... .......... ...195.00 Directional gyro 3 inch vacuum..... ........ ...195.00 Gyro Horizon - electric............................. 295.00 Directional gyro - electric ........................ 295.00 Rate Gyro -electric........ .......................... 135.00 Electric turn coordinator...........................115.00 Electric turn & bank3'..............................105.00 Vacuum turn & bank.................................129.00 Accelerometers ..........................................85.00 Airspeeds.. ............................................. .....50.00 Altimeters ..................................................95.00 Encoding Altimeter 3 pointer ................ 195.00 Drum Type.. ...........................................295.00 Single temp gauge................................... ...35.00

Dual temp gauge............................... 60.00 Standard clock, parts extra............... .40.00 Chrono or stop clock, parts extra ..... .95.00 Standby compass.............................. ..35.00 3'Compass....................................... ..75.00

Electric engine gauge ........................ ..90.00 Engine gauge, capillary type............. 70.00 Pressure gauge 2'............... ........ 35.00 Single Manifold or Fuel Pressure....... 50.00 Dual Manitold or Fuel Pressure ......... .60.00 2'Rate of climb.................................. 120,00 3' Rate of climb.................................. 75.00 Mechanical Tachometer .................... 50.00 Single electric Tachometer................ ..55.00 Dual electric mechanical Tachometer 125.00

WE BUY CORES!! ENCODING ALTIMETERS ALTIMETERS 30,000 ft. IFR.....................189.00 20,000 ft. IFR.....................179.00 20,000 ft. VFR ...................169.00

Blind, IHC...........................275.00 3 pointer (from 7) .....from 595.00 Drum Type (from 7)..from 695.00

Add $10.00 for Millibars

New ACK............................225.00

20,000 ft.............................225.00 30.000 ft.............................235.00

Ameri-King Blind Encoderl70.00 Add S12.00 for special dial.

ALL INSTRUMENTS ARE NEW OR FAA CERTIFIED WITH FULL 1 YEAR WARRANTY.

Call For Our FREE 40 pg. Catalog!!

6391 Fox Run Cir., Jupiter, FL 33458.) Readers are invited to submit entries to EAA's Hints For Homebuilders, Att: Golda Cox, P.O. Box 3086, Oshkosh, Wl 54903-3086. Entries will be reviewed by a panel of EAA judges. Readers whose hints are published in SPORT

AVIATION

will be awarded a 9piece Combination Wrench Set from Snap-on Tools, a $25 gift certificate plus a current catalog from Aircraft Spruce & Specialty, a Lenox 4012 Hacksaw Frame from American Saw & Mfg. Co. and a Pro 360 Digital Protractor from Macklanburg-Duncan. Members are also invited to submit hints of an electrical nature. Any hint used will receive a Fluke Model 23-2 Multimeter with Holster from the John Fluke Mfg. Co., Inc. The contest will run from August through July of each year with a Grand Prize being presented by Snap-on Tools (KR757 Roll

8OO-733-O116 316-683-7571 Fax 316-522-7694 Prices subject to change without notice. Most items shipped same day.

We accept

Cab), Aircraft Spruce & Specialty ($250 gift certificate), American Saw & Mfg. Co.

(Lenox VBKMA-6 Vari-Bit Kit) and Macklanburg-Duncan ($250 cash). A Grand Prize will also be awarded by the John Fluke Mfg. Co.

These awards will be presented during the EAA

orC.O.D. 92 MARCH 1995

Convention.

Our thanks go to our sponsors for these awards.