BH Harmon Rocket (RV-4) 65'' 20cc Gas ARF
- Product Review (submitted on December 6, 2012):
The Harmon Rocket is a large scale model of a very small airplane. The full-scale Harmon Rocket II is a clipped wing, hopped up version of the popular two-place RV-4 homebuilt, and has a wing span of only 21 ft. The Vietnamese BH Models quarter-scale ARF is a beautiful rendition of the Rocket II, with only a 65 inch wing span and a wing area of only 890 sq. in. With the predicted weight of 11 lbs., it would have a wing loading of a respectable 30 oz./sq. ft. This would make it a relatively "hot" flyer, but it does have rather large landing flaps. I am a bit apprehensive about flying this plane, my usual airplanes being Cubs, the Ercoupe, etc. with rather low wing loadings.
The BH model is covered with Oracover, beautifully applied with not one wrinkle. The cockpit area is fully finished, with two seats, a realistic pilot and an instrument panel, inside a large, already-installed canopy. Excellent pre-painted fiberglass wheel pants and a big gorgeous painted and pre-trimmed cowling are provided. The hardware package is quite complete, including light weight wheels, a heavy duty plastic spinner with aluminum back plate, push rods, control horns and clevises, and a formed and painted heavy aluminum landing gear. Most fasteners needed are furnished. Even a safety prop nut is included.
Construction of the Rocket is similar to what I have seen in many of the IMAC and Pattern ARF's, with lots of interlocking laser-cut light ply parts, well-perforated with lightening holes. The removable wings and horizontal stabilizers are mounted on strong aluminum tubes that pass through the fuselage, and are held in place by bolts. The vertical fin is an integrated part of the fuselage. All control surfaces are pre-hinged and installed, with scale-type invisible hinges. Little or no glue is needed to assemble the model. The packaging was excellent, with each major subassembly in its own box within the big shipping box, and small parts in individual plastic bags.
The model Rocket is designed for a 20 cc gas engine. I do not own such an engine, but I am considering some engines that I do possess. .
I have two big Saito 4-strokers, a 150 and a 125. The 150 is in a big Ultra Stick and the 125 is in a BH Spacewalker.
Now 20 cc equals 1.22 cubic inches., so the two Saito 4-strokers would work, with the 150 "stump puller" being perhaps a bit much for that small wing area. Both would fit the motor mount and cowling of the Rocket. The Saito 125 is lighter, and is said to have more power than a 120. So the Saito 125 seems the best choice for me.
After it has been flown, I will put another review here. I am very satisfied with the two BH ARF's I have bought so far. In the Harmon Rocket box was their catalog, with what looked like literally hundreds of different models to choose from. Oracover appears to be a superior film covering, easily conforming to wing tips and other compound curved shapes, and any wrinkles were easy to remove with a heat gun. (the Rocket had none, but the Spacewalker had a few.)