"It's remarkable, the difference in the feel of the airplane," says Aeromarine President Chip Erwin, from his build center in Florida, where he is managing the flight testing on the newest iteration of the popular single-place PSA (Personal Sport Aircraft), the Merlin, now with smooth, economical, 4-stroke HKS power.

The crisp performance hasn't changed. In fact, the early tests are showing near-identical takeoff and climb, but with higher cruise numbers, compared to the Merlin with the Rotax 582 two-stroke, the only engine that has been available in the Merlin so far.

The four-stroke, opposed 2-cylinder HKS and its gearbox weighs a bit more than the two-stroke option. "We moved the battery aft, and the whole airplane gives up about twenty pounds of payload," Erwin says, "but the HKS burns less fuel so its flight time is longer at any given weight." The HKS runs on avgas or premium mogas.

See the Merlin at the Sebring show.

Two HKS-powered Merlins will be at the Sebring Light Aviation Expo this week in Sebring, Florida. "We will also bring a Merlin from our build program that isn't yet 100% completed," says Erwin "and that will give people a chance to see how easy it is to build their own Merlin."

The Merlin has established a reputation as the quickest-build true 51% kit available. So complete and builder-ready is the Quick Build Kit ("There is no Slow Build option," jokes Erwin) that most major assemblies and skins are already tacked into position for shipping (using colored soft rivets), requiring the builder to actually do some disassembly to bring it to the 51% stage.

Erwin says, "Precision matched-hole technology means that the holes punched are not just pilot holes; the accuracy is so high that holes in the skins match the holes in the ribs and bulkheads at final size, so next to zero drilling is required. This precision saves dozens if not hundreds of assembly time hours."

The single-seat all-metal Merlin PSA is already flying in several European countries and in the USA now with both the 582 and the HKS. Merlin PSA quick-build kits with the HKS are now being delivered in the USA with delivery positions available for delivery this spring; some slots remain for the Builders' Center, as well.

The kit (without engine, instruments, and paint) has an introductory price of only $16,500. Depending on engine, BRS, and panel options, completed and painted aircraft cost from $35k to $50k.