Construction demonstration of a super simple Science Olympiad "Flight" event airplane. Half an hour to build an airplane capable of over two minute flights in a typical gym. Construction cost is under $15.00 if building multiple copies to keep shipping cost to a reasonable share of total cost.
UHU Purple glue stick is no longer available. Very Important: test your glue stick before using grocery bag covering. Glue a scrap of balsa stick to the bag material and let sit overnight. If it doesn't bond, use gift wrap tissue for covering instead of grocery bag. Any glue stick will work with tissue. A glue that works perfectly on grocery bag is Weldwood Non-flammable Contact Cement thinned 50% with water and applied per p. 16-17 of this article: www.freeflight...
Buy the propeller, a propeller "front hook" (see the "Parts" page) and one package each of .094" and .087" rubber here: www.freedomfli... Buy the 24cm propeller assembly, not the broad blade flaring style.
Here is the airplane flying over two minutes in a gym: • Flying the Super Simpl...
This airplane is smaller than the largest airplane that could be fit into the maximum size measurement box noted in the rules. This is deliberate. A larger version, with more wing area could be built, but would also be heavier and would probably not fly better.
Construction Details:
Very Important! Notice I am holding the joints together with my fingers before applying a drop of glue on top of each joint so that it wicks in. Gap free joints! Good quality, fresh, CA glue is used. Part weights below are with grocery bag covering; tissue adds 0.6 grams total. Draw your own plan on graph paper; it's easy!
Wing: 16" span total and 3.75" chord; tips are 3.75" span; center section 8.5" span - wing spars and ribs are 1/16"x1/8" sticks, 12-14 lb cu ft wood (36" stick weight = 0.87g-1.05g) plus a 5"x 1/8"x1/8" stick of 16-18 lb cu ft wood wing mount (36" stick weight = 2.3g-2.65g); completed wing = 1.8g
Stabilizer: 9"span 2.75" chord; spars and ribs are 1/16"x1/18" sticks, 8-10 lb cu ft wood (36" stick weight = 0.58g-0.75g); stabilizer weight = 0.6g
Fuselage:
Motor stick: 12" of 1/8"x1/4" 16-18 lb cu ft (36" stick weight = 4.66g-5.31g) plus a small 1/2"x 3/32" stick nosebearing ring mount; rear hook can be bent from a pin; fuselage weight (with rear hook and front nosebearing ring) = 1.85g
Tailboom: 8.5" of 1/8" square 8-10 lb cu ft w/ 1/2" overlap joint to motor stick (36" stick weight = 1.15g-1.5g); tailboom weight = 0.38g
Fin: 2" height, 2.5" base, 1.5" tip; same wood as stabilizer; completed fin weight = 0.18g
Propeller: 24 cm Ikara symmetrical; propeller weight =2.3g
Completed airplane weight = 7.15 grams with grocery bag covering and 7.75 grams with tissue covering.
Notes:
1.Modeling clay ballast on the side of the fuselage just behind the CG point (1" forward of wing trailing edge) to bring total weight to 8.05 grams to meet 8.0 gram minimum weight rule. Ballast may need to be closer to the nose if using tissue covering.
2. Wood should be available from most local craft stores. Buy extra sticks and weigh them to find correct weight/density for each part.
3. You can purchase wood from Specialized Balsa to get correct density. When ordering from Specialized select "medium" density 10-14 lb cu ft wood for wing, stabilizer, fin and tailboom and use the lighter 10 lb cu ft sticks for the ribs, stabilizer, fin and tailboom and the heavier 12-14 lb cu ft for wing spars. Motor stick wood should be ordered as "heavy" density 16-18 lb cu ft.
Trim Settings:
1. Center of gravity (CG) location 1.0" forward of wing trailing edge with the 1.5 gram motor installed and wing mounted with the leading edge 2.5" from the nose of the motor stick.
2. Left wing washin - 0.25"
3. Stabilizer tilt: 3.0 degrees (left stabilizer tip 0.5" higher than the right)
4. Tailboom left turn offset: 3.58 degrees (0.5" angled to create left turn)
5. Tailboom negative incidence: 1.8 degrees. 2.5 degrees mentioned in video, but actual measure of 0.25" tip of tail boom higher than front of tailboom if length of tailboom is 8.0" is 1.8 degrees.
5. Wing incidence shim: 1/16" (video shows using a 1/8" square stick shim under front of the wing attach stick. During flight testing this was replaced with a 1/16" thick shim).
The CG location and all other trim/turn settings are important. If after construction some of the trim settings are not correct, it's simple to slightly crack a joint, or heat (with breath) or slightly wet a spar to bend or slightly crack wood (and repair with a dot of CA glue) to correct wing warps, stabilizer tilt and tailboom offset.
Do not try to fly till all trim settings above are correct! CG can be adjusted by shifting the clay ballast or by mounting the wing 025"-0.5" forward (to move CG back) or 0.25"-0.5" back (to move CG forward).
Brian T
Негізгі бет Super Simple Airplane Build for 2023-24 Science Olympiad "Flight" Event - B Division
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