Author: D. Hull
Edition: Model Aviation - 1999/04
Page Numbers: 54, 55, 61, 62
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Little Tiger

By Dave Hull

This is a simple, multipurpose low-cost Profile Proto Speed model that is easy to construct and offers plenty of fun for kids and adults.

Profile Proto is an excellent entry-level event for anyone interested in Control Line Speed flying. It's an exciting pastime that's bound to get your adrenaline flowing.

Little Tiger has a strong contest record: first in Junior at the AMA Nationals in 1995 (second in 1996); in Open class it placed third in 1995–1997 and first in 1998. With slight modifications the model has served different purposes. It began as a trainer for my stepson, Jeff Macapinlac, in early 1995 and has since been primarily a contest model.

Construction

General

  • Keep the model as light as possible for good acceleration at takeoff. My model weighs approximately 7 ounces (flying weight about 6–7 ounces).
  • Use quality hardwood and firm balsa where noted. Prime and sand parts smooth before final assembly.

Empennage

  • Cut the stabilizer portion of the tail surfaces from firm 1/8" balsa sheet.
  • Sand to a symmetrical airfoil (NACA 63-009): rounded leading edges and sharp trailing edges.
  • Connect the elevator to the stabilizer with Perfect brand cloth hinges and cyanoacrylate (CyA) glue, applying glue only to the nonmoving part of the hinges.
  • Cut the rudder and wingtip control line guide from 1/32" birch plywood.

Fuselage

  • Use the hardest piece of 1/4" x 2" x 12" balsa you can find for the beam-mount fuselage.
  • Nose section: use 1/4" x 1/16" maple engine mounts sandwiched between two 1/8" birch plywood doublers, bonded with epoxy.
  • Carve and shape the canopy from a sheet of Plexiglas®.

Landing Gear

  • Form the landing gear from 1/16" steel wire.
  • Securely attach to the fuselage with safety wire and epoxy.
  • Use 1" diameter streamline wheels (from K&B or Glenn Lee) held with small washers soldered in place.

Wing

  • Make the wing from a stiff medium-hard piece of 1/4" x 4" x 16" balsa and carve/sand to a symmetrical NACA 63-009 airfoil.
  • Cut a slot in the center of the wing for a 1/4" square spruce spar, 4" long, used for the bellcrank anchor.
  • Bellcrank anchor and bellcranks can be obtained from Ned Morris or Kustom Kraftsmanship.
  • Pushrod: .035" music wire.
  • Control horn: .015" tin.

Controls

  • Simple exposed controls are required for a Profile Proto.
  • No binds or sloppiness is allowed—controls must be free and precise.
  • The pressure line goes to the top of the tank; the fuel feed line comes out the bottom.

Engine

  • The airplane has been flown with various .049 engines:
  • Cox Black Widow .049 (training flights)
  • Cox Tee Dee .049 (early training)
  • CS .049 (contest/Nationals)
  • The fuselage plan shows mounting holes for CS; other engines may use adapter plates. Mounting plates are secured with 3-48 screws and blind nuts using the CS holes.
  • Tee Dee and Black Widow engines are lighter than the CS and must be mounted farther forward for proper center-of-gravity placement (within 1/8" of the wing leading edge).

CS Engine Modifications (used on contest model)

  • Raise the exhaust port and open the timing to about 157° (stock timing is 142°). The easiest method is to shim up the cylinder liner 0.025" with a gasket under the top flange where the liner seats the crankcase.
  • Install a hemi head (e.g., by Jerry Rocha) that accepts Nelson glow plugs; similar designs made by Doug Galbreath and Walt Gifford have been used. The stock CS head works well but typically needs to be set higher than the hemi; use cylinder head gaskets to adjust head clearance for weather/optimum performance.
  • Use a crankcase-pressure fuel system. Tap a 0.010" pressure fitting into the center of the engine backplate.

Fuel

  • All-out racing fuel formula used: 70% nitromethane, 10% castor oil, 10% Klotz synthetic lubricant, 10% propylene oxide.
  • Editor experience: be cautious reducing oil—insufficient oil will wear the engine. For high-speed flights Dave later recommended at least 18% total oil (4% castor, remainder Klotz synthetic).

Propeller

  • Preferred: fiberglass 4-3/8" x 4-1/2" prop made by Mike Hazel.
  • Cox prop option: gray Cox prop (recommended: start with 5-1/2" x 4" gray Cox prop, cut diameter down to 4-3/8", then carefully balance before running). Several fliers have had good results with modified Cox props.

Finish / Final Assembly

  • Prime and sand all parts smooth before final assembly.
  • Apply K&B Super Poxy primer paint; use no more paint than absolutely necessary to keep weight down.
  • Use medium CyA for final assembly.
  • Make the fuel tank from .008" tinplate or brass shim stock and solder together.
  • Mount the tank with rubber bands attached to a couple of .035" wire hooks looped through the fuselage.

Flying

  • Always keep safety in mind. Conduct a thorough preflight check: fuel lines, glue joints, screws, nuts, bolts, etc.
  • Ensure flying lines are kink-free and controls operate without binds.
  • To fill the tank: disconnect the pressure line from the tank to vent it, then fill through the fuel line after disconnecting it from the needle valve assembly.
  • After filling, keep the nose up until starting the engine to prevent flooding.
  • Stay clear of the prop, which is hard to see when running.
  • Preferred flight direction: clockwise around the circle so engine torque helps keep the lines tight at takeoff. If flying counterclockwise, be prepared to step backward at launch to maintain line tension and control.
  • Little Tiger accelerates quickly from launch and is fast, stable, and exciting to fly.

Editor's Note (Dave Hull — Nats report)

  • After submission, Dave Hull won the 1998 Nats with this model.
  • New best official speed: 109.98 mph for a standing-start Proto flight.
  • Earlier unofficial: Al Stegens clocked the airplane at 120 mph flat for top end and 114.68 mph standing-start Proto time (would have been a record, but disallowed for not getting into the pylon within 1.5 laps).
  • Head clearance on the winning and unofficial 114 mph flights: set at .008".
  • For the fastest two flights Dave dropped oil content from 20% to 14%, which resulted in some loss of compression—insufficient lubrication. He does not recommend such low oil unless you accept rapid engine wear.
  • Future recommendation: at least 18% total oil, with 4% castor oil and the balance Klotz synthetic oil.

Sources

Note: K&B Manufacturing and Kustom Kraftsmanship are advertisers.

  • Glenn Lee, 819 Mandrake, Batavia, IL 60510
  • Doug Galbreath, 3408 Topsail Pl., Davis, CA 95616
  • Ned Morris, 9044 Rushmore Blvd. S., Indianapolis, IN 46234
  • Mike Hazel, 1073 Windemere Dr. NW, Salem, OR 97304
  • Dave Hull, 3885 Baldwin Dr., Santa Clara, CA 95051

Specifications

  • Type: CL Profile Proto Speed
  • Wingspan: 15-1/2"
  • Engine: C.S. .049 (commonly used)
  • Flying weight: 6–7 ounces (approx. 7 oz)
  • Construction: Balsa and plywood
  • Finish: Epoxy (K&B Super Poxy primer)

Full-Size Plans Available — see page 165

Transcribed from original scans by AI. Minor OCR errors may remain.