Apache (oz7050)

About this Plan

Apache. Free flight power model. For Ohlsson 60 or similar engine.

Quote: "Foolproof retractable landing gear, wing slots to kill stall, and automatic and adjustable sailplane 'spoilers' to prevent undesired out-of-sight flights make this trim warrior your best contest bet. Power is by Super Cyclone.

Every possible device for obtaining maximum stability and efficiency has been incorporated in the Apache, without sacrificing the realistic appearance most modelers desire. Stability is achieved by the proven set-up of high wing, large stabilizer, and proper rudder design, plus built-in tip slots. These delay the stall of the tips when the wing reaches a high angle of attack, overcoming the tendency to fall off on one wing and start a spiral dive. The stabilizer is set low out of the turbulent wake of the wing airflow, affording greater stabilizing action at high angles of attack.

Efficiency is attained by 'cleanlining' the ship without using fancy construction. In order to make a retractable landing gear practical, a singlewheel design was necessary. The system used is positive in action and can be locked in extended position for test flying. The inclosed cockpit has been carefully worked into the fuselage lines to reduce its effect to the minimum. Construction is practical throughout, with no difficult wood bending required.

The motor unit is designed for instant checking and shock-absorbing qualities. Should the propeller or engine strike an obstacle, the motor bulkhead will swing out, with the pivoted battery track following without raising havoc inside the fuselage.

To facilitate transportation, the wing and stabilizer are removable, and are keyed to assure replacement in their proper positions when ready for flight.

Powered with an Ohlsson 60 or a Brown, the required weight under AMA contest rules is 3 pounds, giving the ship a wing loading of 8.2 ounces per square foot, while with the Super Cyclone the minimum weight is 3 pounds, 4 ounces, raising the wing loading to 8.8 ounces per square foot. Any of these engines will pull the Apache high into the sky where its slow, flat, soaring glide will take advantage of every foot of altitude gained under power.

Fuselage Construction: The fuselage is built up around an inner frame of 1/4 in square balsa to simplify alignment. Lay out the side view in full size using the fuselage dimension chart given on Plate I. Note that the dimensions are given from the outside of each longeron to the center line. Assemble both sides at the same time, one atop the other to assure their being exactly alike. Join the sides from Stations 1 to 7. Pull the longerons together at the rear-and install the stern block of 1/2 in sheet. Fit the required cross pieces to complete the structure.

Now decide whether you wish to install the retractable landing gear, or prefer the conventional two-wheel type - which is best attached later directly to the motor bulkhead.

The operation of the retractable gear is fully explained on the plans. Cut out the two main plates F-2 of 1/8 plywood. Make the bearing fittings consisting of 3/16 OD tubes with .040 brass strap (F-3) soldered to them. Be sure that the inside diameter of the tubes is slightly more than 1/8 in to allow the struts to slide freely. Bolt these fittings to the plates using filler blocks to get the proper width for the struts..."

Supplementary file notes

Article (2 parts).

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction