March 1995
by Ron Leuck

The decision to build a Merlin was not an easy one. There are a lot of good aircraft in this specific class to choose from. We needed an airplane to demonstrate our floats and our primary considerations were that the airplane had to have good STOL performance and a large cabin.

We were given the opportunity to fly a variety of aircraft at Sun'n Fun in 1994 where we met the folks at Merlin who introduced us to their airplane.

After careful consideration we decided to purchase a Merlin because it met all our criteria. We placed our order a month after the show.

The long-awaited day for the arrival of the kit finally came. Like two children on Christmas morning, my partner Steve Young and I hurriedly unpacked our new toy. We carefully laid out all the parts for inventory and much to out delight every single part was there. We had heard so many stories about partial kits being sent to customers by different manufacturers so it was a real treat to find all of the pieces there.

Construction began immediately. With both of us able to devote a lot of time to the project we hoped to have the Merlin in the air in under two months. Merlin advertises 400 man hours for completion. We were able to complete our Merlin in just under 350 man hours.

Now began the more mundane tasks associated with building any airplane, the small parts, and there were many. We decided to follow the plans and build the wings first. There are a number of small parts to fabricate for the wings and the full-sized templates for each of these parts sure made life easy.

Each of the 14 wing ribs are a foam core with an aluminum cap strip on the top and bottom. Using the full-sized template as a pattern, the foam cores were easy to cut accurately to ensure the wing would have the proper contour. The preformed aluminum cap strips are secured to the ribs with strips of aluminum and rivets.

Once the prefabricated leading edge "D-Cell" was jagged up on the bend, the rib gussets and ribs were riveted in place, paying careful attention to ensure everything lined up straight. The preformed trailing edge is riveted on and then the drag brace is installed.

Both wings are temporarily installed on the fuselage and the aileron system put on. The ailerons themselves were a little tedious to build, fortunately most of the parts were prebuilt. At this point the airplane begins to take on the shape of an airplane, not just a bunch of parts. We decided not to put lights on this airplane so there was nothing more to do to the wings until it was time to cover them.

The fuselage comes prewelded which means there is no welding or jigging required. With the wings still on the fuselage, the aluminum gap cover between the two wings is fabricated and installed. We added four small sky lights in the gap cover for better upward visibility, a Lexan gap cover is offered as an option but operating an airplane in Florida is hot enough without some shade over your head.

The tail feathers are now installed and the cables are strung in the fuselage through their fairleads. With all of the control surfaces hooked up and working it was hard resist some "hangar flying".

The instrument panel is fitted and all of the instruments are temporarily installed before the glare shield goes on. We do not have any radios in the panel, By using a hand-held nav/com and hand-held GPS we avoided any complicated wiring.

Mounting the Rotax 582 engine and hooking it up is a straight-forward operation. When it came time to mount the radiator we made our first major change to the Merlin. We decided to mount the radiator on the inside of the cowling rather than on the outside of the airplane under the fuselage. This decision was both practical and aesthetic. With the radiator on the outside of the airplane it is subject to more abuse than if it were mounted inside the protection of the cowling.

Fitting the fiberglass cowling and attaching it to the airframe presented no problems for there was ample room for everything to fit. The windshield came as a flat sheet of Lexan and although it is rough to cut it must be cut and fit in place.

"This was the scariest part of the process for neither Steve nor I had ever covered a fabric airplane."

The baggage compartment must be permanently installed before the fuselage is covered. Trial fitting the doors and floor boards is done before covering.

It is now time to disassemble the airplane in order to cover everything. This was the scariest part of the process for neither Steve nor I had ever covered a fabric airplane.

We started with the wings, lower surface first. Armed with the Stits book and a pair of scissors we decided to jump in and do it. The first wing was the worst. Once the fabric was cut and glued it hung and sagged everywhere like a cheap suit. If we could not accomplish this feat it wouldn't even remotely mumble an aircraft wing.

The final transformation from the loose fitting bedsheet to that of a taunt wing skin was incredible. Watching the wrinkles disappear as the heat of the iron shrinks the Dacron was almost miraculous. Maybe this wasn't going to be so bad after all.

With both sides of the wing done it was time to tackle what turned out to be the most challenging part of the covering process, the fuselage. Unlike the wing the fuselage is a compound shape. With a lot of planning thought and a little luck the fuselage was finished in two days The control surfaces are covered last using the trim pieces from the wings and fuselage.

Following the Slits process from start to finish is the best way to finish a fabric airplane. We started with two coats of poly brush to seal the fabric, followed by five coats of poly spray to ensure a UV barrier. The top coat is poly tone which does not give the shine of a urethane but we were advised to do so in order to prevent cracking of the finish.

The other advantage of the poly tone paint is the ability to easily fix any hangar rash.

With the airplane finished and painted it was time to mount the floats. This was the first time we mounted our floats to a Merlin and although we have floats on similar designs, the first time on any design takes a little longer. We mounted a pair of straight floats first, this makes for a simpler installation and if we need to change the location of the floats it is far simpler without landing gear. The drawback is that the first the airplane is flown it has to be flown from the water.

We brought the airplane to the airport for final assemble and for our local designer to sign it off. We are lucky to have John Murphy as a Chapter member. He is our local designer in addition to signing off airplanes and he is always available to give advice. You would be hard pressed to find a more qualified person and he is a great guy too. With his blessings and the usual paper work it was time to find out if all of this hard work was going to pay off.

We chose to fly the airplane first thing in the morning to ensure minimal winds and better flying conditions in general. There was a slight breeze from the north and not a cloud in the sky. Perfect flying conditions. Because there was no landing gear on the airplane, it was loaded on the trailer and towed to the end of the runway. We are fortunate the runway at the Merritt Island airport extends into the Banana River.

The airplane was carefully slipped into the water and floater perfectly. It was time to start the slow speed taxi tests; manoeuvrability and stability are the first tests. The speed of the airplane is slowly increased until just below rotation speeds are reached. After each series of test runs is completed, the airplane is brought back to shore to be checked over to look for any leaks or loose parts. During this series of taxi tests, aileron, rudder and elevator authority are all checked for effectiveness.

With a morning of taxiing around under my belt it was finally time to fly. A lot of things run through your mind as you advance the throttle for takeoff for the first time. Did we tighten everything? Even though you check and double check everything and then the inspector inspects everything again, you can't shake that feeling like when you leave for a vacation and you ask your wife as you cross the state line, "Are you sure you unplugged your curling iron?" Even though you are sure she did.

When lift-off occurs and you slip the surely bonds of the earth on your silver wings, you know everything is going to be okay. A quick check of all of the controls verify that the airplane is well trimmed, followed by an uneventful landing and taxi to shore. Wow, that was easy.

Pull the cowling and check over the engine, look over the airframe. Nothing is coming apart so I guess it is time to fly some more.

With the first flight behind me now I can concentrate on the important aspects of the airplane. Taxiing into position and applying full power made for a brisk acceleration and I was airborne in less than 10 seconds. At a climb speed of 60 mph I reached an altitude of 1,000 feet in 40 seconds. Levelling off at 1,000 feet it was time to explore control feel and speed ranges.

Increasing the speed in five mph increments, feeling for abnormalities, I flew the Merlin to its top speed of 98 mph. Bringing the power back to 75% or 5800 rpm, yields a cruise speed of 84 mph. At this power setting the engine burns five gph with 13 gallons of fuel on board, giving a range of 176 miles with reserve.

With several hours on the airplane it was time to mount the amphibious floats. The amphibious floats mount the same as the straight floats with the addition of some cables. Two days later we are ready to take to the air again only this time I am going to take off from the runway. Acceleration on the land is brisk and I was airborne in less than seven seconds using less than 100 feet of runway. Again climb to 1.000 feet at 60 mph was clocked at 40 seconds. All the speeds and power settings were the same. When the 10 hour restriction had been flown off, it was time to see how well the Merlin handled two people aboard.

Our Merlin weighs in empty at 712 lbs with a gross weight of 1300 lbs that leaves us a useful load of 588 lbs. That's two 200 pounders, 13 gallons of fuel and 110 lbs of luggage. With the airplane loaded to gross weight, take off from the land was under 200 feet and 350 feet from the water. Climb rate suffered somewhat from the weight but still remained a respectable 900 fpm.

At full gross weight stall speed is in the neighborhood of 45 mph, with a 75% cruise of 80. Not bad for only having 65 hp.

If you are looking for a reasonably priced, well-behaved, fun airplane with a good cruise speed, high useful load, in a well built, easy-to-build kit, look closely at the Merlin.

For more information on AeroComps "Super Floats" please contact us at AcroComp Inc., 275 Manor Drive, Merritt Island, FL, 32952; Tel.: 407-453-6641.

Reprinted/Distributed with permission
by Ron Leuck ; Canadian Homebuilt aircraft news; March 1995
copyright 1995