Since 1986 the Big Hots giant fun fly aircraft has obviously had a place in I.M.A.A. member's hearts. As we read over the Chapter Event reports sent in to High-Flight, there seems to be pictures of at least one in every stack of photos. With its 91" wingspan the Big Hots requires a lot of power to do breathtaking maneuvers and with a one piece wing it takes a truck, van or large station wagon to transport.
Dan Santich, created and designed the entire Hots line (the first .40 size model appeared in 1983) and he has certainly noticed our interest in his giant model. He was so impressed with the I.M.A.A. and what we stand for, fun flying with no competition, that he has designed and built a model around our guidelines. The Ultra Hots has an 81" wingspan and is the latest in a series of great flying models from his model company.
The Ultra Hots was first flown at Oshkosh by Dan and the participants were waiting at his booth every time he would return from flying. The membership wanted to know more about his I.M.A.A. 1egal "Hots" that is easier to transport, requires a little less power to perform spectacularly and is so easy to build.
Dan and your editor have known each other for many years. While he was editor of "Model Airplane News," he guided my fledgling career as a model aircraft industry writer. Two months prior to the Oshkosh Rally we had begun building an Ultra Hots to present in the pages of High-Flight. While I had not seen one fly, Dan sent me a video tape of his prototype in action and we knew it was a winner. I had built and flown the .40 Hots, .60 Super Hots and have a Giant Hots (in the bones) ready to be covered, so I was familiar with Dan's construction process ... as many of our members are.
The design philosophy Dan instilled in his original Hots has carried through to the Ultra Hots. It is a simple, quick airplane to build and it simply flies great. If you want to tinker with retracts, multi-angle flaps, hydraulic systems or hard to get at engine adjustments look else where. The Ultra Hots is a flying man's model.
Besides the fact that Dan designed a giant model especially for I.M.A.A. members (remember that 81" wingspan could have easily been 79"), what we like is the model's wide acceptance of engines. The Ultra Hots will fly well on many, many engines including the: St 2000 A 3000, Webra Bully, Saito 2.70 A 300, Enya 2.40, OS 2.40 & 3.00, Q-35 & 40, OPS Maxi, G 23 A G 38, Sachs 2.S A 3.2, etc. Just about anything you care to hang on the front will fly this model and fly it well. The secret is its wing loading.
With a wingspan of 81" and a flying weight of 12 lbs., the wing loading works out to around 15 ozs per square foot! The Ultra Hots has 1400 square inches of wing area with a root thickness of 3 inches! I think you get the picture. The Ultra Hots is capable of virtually any maneuver and as you will see in the flight analysis ... it is!
The Kit:
The tens of thousands of Hots kits before the Ultra are shown in the kit you receive. It is shipped in a two piece triple wall cardboard box and the contents are protected with a sheet of plastic that covers everything. The plans are professionally done and all parts are identified on the two large sheets. There was no die crunching in this kit; rather, every piece is machine cut and sanded. Each individual piece is identified with a stick-on label so you don't have to sand off the mark. The smaller pieces such as wing screws and cowl screws are packaged in plastic bags.
The fiberglass cowl is manufactured by Fiberglass Specialties T & D and is ready for paint as it comes. ( Steve Durecki, the President of Fiberglass Specialties has become the primary supplier for cowls and fiberglass accessories to both manufacturers and individuals. He has a booth at many shows and events including our annual festivals, so take a look at the difference in their workmanship.) The landing gear is made from dural aluminum and is very sturdy.
Usually when you open a kit and see all the pieces and blocks of wood you may think of the hundreds of hours of work involved and set it aside until you get your breath! With the Ultra Hots you can't wait to get started and it takes less time to rough an Ultra in than it usually takes to figure out the plans and parts on some other kits.
A lot of this has to do with the absolute simplicity of this design. Dan told me, "Roger, I designed the Ultra Hots to be flown and enjoyed. It's big enough to have the flight characteristics your members like yet it is easier to transport. I put a lot of time in making it quick to build including making a video tape for the builder ..." This tape is invaluable. I have built a lot of models and consider myself an experienced builder, but the tape not only gave us a pace to follow, it taught me a few new tricks in building and covering. We would strongly suggest that you get the tape along with the kit.
Construction:
The sequence of building starts with the fuselage. You
glue a piece of 1/8th balsa to each fuselage side to achieve full
length and then add 2 Lite-ply doublers. The rear is braced with
1/4" square balsa strips and the engine bulkhead is made up of
two pieces of aircraft grade 1/4" plywood which you glue
together. You then mount these plus the wing mounting
bulkhead and the rear bulkhead vertical on one side, gluing on
the other side of the fuselage. Glue the rear end together,
put your landing gear block in place, and you can sheet the
bottom.
The center fuselage top is removable for easy access to the fuel tank and wing screw. The top rear portion of the fuselage is assembled from pre-cut balsa pieces and also uses 1/4" square balsa strips for braces. The stab is already cut to shape from 3/8" thick balsa. You assemble these and glue them in place. At this point your fuselage is nearly done!
The wing is even easier. The spars are 1/2" square
basswood and 48" in length. You don't cut them at the center but run them
full length and then join the extensions at the outer panels. This
gives you a very strong wing! Pin your lower spar to your table
over the wingspan and glue the ribs in place. Then you add the
top spar, leading edge, trailing edge and wing sheeting. Add
your wing servo mounts, wing tips and wing hold down block
.... your wing is completed. The Tailfeathers are 3/8" solid balsa
and pre-shaped.
Now place your wing in position on the fuselage and
mark the location for the 3/8" wing dowels in the leading edge. Drill
the holes, glue the dowels in place, then mark the spot for the
1/4 x 20 steel wing hold down screws. Drill your hole and then
tap the block in the fuselage. Put the wing screw in to hold the
wing and then you build the top center section which is
removable on the Ultra Hots. Take the wing back off and finish the
top front of the fuselage with the pre-cut pieces of 1/8" balsa
and the plane is built.
All that is left is to assemble the wheel pants, sand the control surfaces and mount your landing gear. Wheel Skirts are formed from balsa for light weight. The 1/8" ply insert butts to the dural gear leg. Sand all the balsa surfaces until they are smooth, remove the balsa dust witha tack cloth and you are ready to cover. We used Super Monokotewith white and multi-color striping.
O.S. sent High-Flight the first BGX-1 engine in the U.S. for testing and presentation to our members (see page 26 & 27 of the last issue) and what better power plant to put into the Ultra Hots! This 34.97 cc (2.13 cu. in.) giant proved to be a strong performer during our bench testing, turning a 18 x 10 Zinger at 7,500 rpm with about 4 BHP. It had to go on this giant!
We installed the engine inverted with a J'Tec Snuf-Vibe
isolation mounting system. Somehow John Tatone is able to
have engine mounts built specifically machined for the newest
engines ... in this case before the first one even arrived for
testing! Few things are as painful as having to make a motor
mount fit ... with a J'Tec you get a precision machined, drilled
and tapped unit made specifically for your giant engine. Due
to its compact size and silencing ability a J'TEC "Giant Snuf"
muffler was also installed keeping the powerful BGX-1's
"bark" down to 97 db's. We installed one of Bob Obenberger's
bar stock aluminum Tru-Turn spinners on the front.
The Dural Gear mounts to a 1/4" ply plate. Simple yet strong. I installed a 24 oz. Kraft fuel tank, surrounded with foam rubber. The radio space available in the Ultra Hots is large enough for virtually any radio or set up you can think of. A JR PCM 10 system was installed using their 1031 servos and an SR 1000 mah receiver battery pack. Per the instructions, each aileron has one servo and is connected with a "Y" harness. Dave Brown's fiberglass pushrods controlled the elevators and rudder with a Dubro cable for the throttle. Williams Brother's wheels were bolted on the main gear and a CB heavy duty tail wheel assembly was placed under the tail.
The balance point for the ultra Hots is right on the main wing spar. At that point the model should nudge nose down just slightly. When I picked mine up to balance it I couldn't believe it. It came out perfectly but what was amazing was how light this giant Ultra Hots is. In my hands it was ready to fly and it weighs in at 12 1/4 pounds. Oh what we were going to do with this aircraft!
Flying:
Earlier I mentioned that the Ultra Hots, like the other Hots aircraft, were made to fly. This is not a scale model (although Dan mentioned a full scale Hots in the works!) and since most of us build to fly, this is where it all comes down to. When Dan told me that "your going to find the Ultra Hots a joy to fly..." he was right. The take off was absolutely effortless and the control response was exact. It will do exactly what you tell it to do and nothing more. The tracking is so good it is hard to believe.
We flew the Ultra Hots at a sod farm near Clarkston, Michigan on 3 different days. We were most impressed with its slow flight characteristics... they are incredible. The 3-inch thick wing and light wing loading will allow you to walk it around without fear of it stalling or falling off on a wing. We experienced no pitch tendencies at all with power changes and the BGX-1 would rocket the Ultra-Hots around the field.
Rolls are crisp and with the JR PCM 10 set on maximum throw the Ultra Hots would loop in a tiny circle ... once again never falling to one side or the other. But as we said, the test pilots were most impressed with its slow flight characteristics which is most evident at landing. The design work that Dan Santich put into the 81 " Ultra Hots shines most when you throttle back and pick a spot to land ... it's that easy. Few aircraft, other than gliders or oldtimers, can land at such a slow speed ... yet open the throttle, point the nose up and with the O.S. BGX-1 roaring our Ultra Hots disappear straight up!
Conclusion:
Not only has Dan designed a kit for I.M.A.A. members but he has given us an airplane that has an unbelievable flight envelope. With thousands of hours of design in the Hots line this Ultra Hots is the newest "thoroughbred" in a long list of winners from Dan Santich.
For further information contact:
Dan Santich Models, Rt. 2, Box 293, Pinnacle, NC 27043 Phone 919-368-4414. O.S. Engines, Your local hobby shop or, 1608 Interstate Dr., P.O. Box 4021, Champaign, IL 61820 J.R. PCM 10 radio system, your local hobby shop. SR Batteries, Custom battery packs for R/C aircraft, Box 287, Bellport, New York 11713 Phone 516-286-0079. J'TEC, 164 School St., Daly City, California 94914 Phone 415-756-3400 Tru-Turn Spinners, P.O. Box 836, South Houston, Texas 77587 Phone 713-943-1867