Charles Hooper Sportstar LSA on the Ramp
By Dan Grunloh, Editor – Light Plane World, EAA 173888
These photos are a first look at Sportstar N47CC, a one-of-a-kind light-sport aircraft (LSA) designed and built by Charles Hooper of Lakeview, Arkansas. The fuselage is “S” glass and carbon fiber. The cantilevered wing, rudder, and stabilator are all metal. A single stick in the center controls the aircraft. The firewall-forward is from a Zenith 601, and the engine is a Jabiru 3300.
The primary design criteria included cantilevered wing, center fuel tank, single control stick, wide cabin, Jabiru engine, and fitting within the LSA specifications. No metal fuselage frame is required due to the cantilevered wing construction. The main landing gear is a modified Zenith 601 gear. The airfoil is of his own design.
The cantilevered wing was made using known wing structural materials and procedures. Charles ran some numbers on the structure based on the technical data supplied by the manufacturer of the materials. What is unique is that the skins of the wing are continuous, top and bottom from wingtip to wingtip. This quality makes it a super monocoque wing structure. Small round windows were added for rearward visibility. Round is a great geometric shape for strength and continuity.
Artistic display of some of the wing and aileron parts
Charles is no newcomer to homebuilt airplanes. He has built seven other airplanes: Pitts Special S1C, Glasair TD, Glasair RG, Glastar TD, Pitts 12, RV-9A, and RV-7. With all these aircraft, a builder is faced with a multitude of construction skills. The Sportstar is the first airplane he has designed completely from scratch. He wanted an airplane of his own design so as not to copy another design.
Center section of the wing shows a false spar used to fuel-proof the wing.
The performance of the Sportstar is this—cruise speed at 2900 rpm is 120 knots, and the stall speed at gross is 44 knots. The Jabiru engine will turn 3300 rpm in the Sportstar. Normally cruise is at 2750 rpm which is a comfortable usage of the engine power. At this rpm the fuel burn is 4.7 gallons/hour indicating 110 to 112 knots. He uses 90 plus octane auto fuel. Climb-out at 80 knots indicated will yield 1,000 fpm. There are no flaps.
Joining of the three wing sections, left, right, and center
He has approximately 60 hours of flying time on the machine, but there were some unusual first-flight experiences. Briefly, the radio fell out of the panel, instruments went blank, yaw problems, aileron flutter, and of course, pilot inexperience in the model. Charles said, “I wouldn’t go into detail because I scare myself just writing about it. I laugh about it now, but at the time I was really busy. All the foregoing problems had fixable solutions and were resolved in a matter of weeks. I now have a great flying airplane. I would be remiss in the truth if I didn’t tell you that after the first flight I was deep in thought with the idea of using a chainsaw on the Sportstar. However, due consideration of possible fixes proved to be an easier resolution.”
To prepare for the windshield installation, a mold of the same area was made and sent to a plastic company in Philadelphia that returned the finished windshield.
The flying tail uses a tubular spar and is operated between two HMW plastic bearings that are bolted to the outside of the fuselage. It’s simple but practical. The first flight was done with a split rudder system; the purpose of the split rudder was to provide some air braking on approaches to land. The system worked very well as a speed brake but wasn’t worth a nickel as rudders, thus the yaw problem. Charles said he forgot one important rule when designing a moveable control surface. In order for the control surface to perform correctly, you must have both a high-pressure side and a low-pressure side. The rudder system didn’t articulate; that is, when you press left rudder the left side of the rudder moved left, but the right side of the rudder stayed straight. Therefore the low-pressure side wasn’t good enough to properly move the rear of the fuselage. The system should have been designed so that both sides of the rudder moved in the same direction at the same time.
Buying unfinished materials, as opposed to fabricated parts, resulted in significant money savings. He spent about $2100 on gear legs, wheels, axles, tires, etc; $18,600 on the firewall-forward package which included engine, engine mount, air box, and all other items under the cowling; about $3800 on structural and sheet-metal material; and about $3000 on carbon fiber, “S” glass, and structural epoxy. Throw in about $6000 for instruments and $1000 for paint, and the total is approximately $34,555. Charles said, “Of course, add in about a million dollars in labor.”