Midwest Aerobat – Acrobat Trainer

MOVIE FILES

Midwest offers one of the best basic trainers available, the Midwest Aero-Star 40 ARF. Since its inception as a kit back in the mid-1980’s, and now as an ARF model, the Aero-Star has taught thousands of model pilots to solo and even to go a bit beyond. As the review of this fine basic trainer elsewhere in Sport Aviator shows, The Aero-Star 40 performs loops and slow rolls fairly well and can even be talked into doing a fair stall turn (with lots of opposite aileron to keep the wings from turning when full rudder is applied).

But, as it does to every new model pilot that stays in the sport, the time must come when basic trainer aerobatics are no longer challenging. Yet, the experience and skills for safely piloting very quick, fully aerobatic scale or competition aircraft remain just over the horizon. Well, Midwest has an answer to that and one that was a very surprising experience to build and fly.

 
Photo 1   Photo 2

This surprising model is called the Midwest Aerobat and, like the Aero-Star 40, is part of their “Success Series” of model aircraft. After studying both aircraft, I think Midwest must take this “Success” idea very seriously. There are few ARF models that are as easy to build straight as is the Aerobat. The vertical fin is already attached (Photo 3). The horizontal stabilizer bolts in place even though epoxy is also used. The bolts make it easy to get the stabilizer properly aligned. Except for the Aero-Star, I don’t remember ever building an ARF model that used both glue and bolts, by design, to hold the stabilizer in place. I can’t think of an easier way to build a strong but straight tail section.

 
Photo 3    Photo 4

There are several “Success” features on the Aerobat. We will try to cover them all as we build the airplane. Besides having the vertical fin already mounted, the Aerobat is delivered with both fuselage control rods already assembled (photo 4). This seemingly minor prefabrication actually saves more than an hour’s work. Besides, most new model builders usually have difficulties making good, straight pushrods. There is usually far too much “slop” or the control surfaces do not center properly because of pushrod binding against the fuselage’s internal parts.

Assembling the Wing

Constructing the Aerobat’s wing is fairly routine for an ARF model. There isn’t much to do, but the Aerobat has one Success feature that is different from most aerobatic trainers. The Aerobat features dual aileron servos, one for each aileron, which enhances the aircraft’s performance and flexibility. Dual aileron servos provide more stable control surface movement as well.

The Aerobat uses a semi-symmetrical airfoil for good inverted performance. The airplane also has much less wing dihedral than a basic trainer would have. Reduced dihedral enhances roll and inverted performance but does reduce the wing’s total lift a little. We point this out at this construction stage since the first assembly step involves gluing the wing halves together. The Aerobat uses a single plywood spar for support. Since there is not much dihedral, it is possible to mistake which side of the spar goes “up” during construction.

 
Photo 5   Photo 6

It might be helpful to use a small light, as in photo 5, to identify the slight angle in the spar. The small “V” in the spar should face downwards once in stalled. The spar itself should point slightly upwards, away from the wing’s center section as in photo 6. This may sound too basic but such assembly mistakes have occurred.

 
Photo 7    Photo 8

Since the ailerons are factory installed, the next step is to glue the wing halves together with epoxy. I suggest using two different epoxies for this task. Use slow, 30-minute cure epoxy for the spar and its mating slots. Use 12-minute dry epoxy for the center ribs. Using slow epoxy for the spar means you do not have to hurry construction.

If you enlarge photo 6, just click on the picture, you can see that there is a midpoint line marked on the spar itself. Draw this midpoint line before installing the spar. Most ARF wing spar sockets are slightly longer than required to insure there is enough room to insert the spar. The Aerobat is no exception to this rule. Apply the slow drying epoxy into the spar sockets (photo 7) and onto the spar. Make sure to put some epoxy on the spar ends as well. Put the spar into one wing socket (photo 8). Put the slow-curing epoxy into the spar socket inside the other wing half.

 
Photo 9    Photo 10

Using an epoxy brush, available at all hobby stores for about 15 cents each, spread a thin coat of 12-minute epoxy on one center rib. Put additional slow drying epoxy on the spar and slide the other wing half onto the spar until it is tight against the center rib. Then use low tack masking tape, like Scotch™ Brand 2090 Long Mask™ Masking Tape to hold the wing halves together. Make sure to apply tape to the bottom of the wing as well.

Note in photo 10 that there is a small modeling clamp on the wing’s trailing edge. This clamp keeps the two wing halves aligned while the epoxy dries. It is very important that both wing halves be aligned; so check the leading edge as well. It might be necessary to hold the wing halves in position. That is why 12-minute epoxy was used for gluing the center ribs together. Once this epoxy sets, the wing halves will not move out of position while the slow epoxy cures.

 
Photo 11    Photo 12

Sometimes when assembling an ARF kit, even though the wings are tightly assembled and the correct is dihedral established, a small opening occurs on the top or bottom of the wing joint. This is not unusual. As long as everything is correct, this slight opening is not critical but should be filled. Epoxy alone does not like to bridge gaps, as the cured adhesive can be very brittle.

Photo 11 shows the items required to fill structural gaps like the one shown in the photo (enlarge for better view). Use a mixture of 5-minute epoxy and micro-balloons, available in every hobby shop. The mixture should be thick but able to flow. If this is your first time using this form of structural reinforcement, practice a few mixtures first.

Cover the wing center section with low-tack masking tape (photo 11). Apply the micro-balloon/epoxy mixture into the opening part of the center slot (photo 12). Work it into the open areas and then wipe away all the excess mixture before curing begins. Once cured you have a wing that could be used as a small bridge if necessary. Use this method to fill structural gaps anywhere on any aircraft. Thicker mixtures can be used to construct reinforcement fillets at important joints like firewall/fuselage joints and landing gear attachment areas.

 
Photo 13    Photo 14

The Aerobat uses two wing servos for aileron control. This is the same control arrangement used in competition model aircraft. Most servo wires are not long enough to reach the wire exit point near the wing’s center section. Therefore a 9 in. extension is used to make up for the missing length (photo 13). It is a good idea to insure the extension wires never unplug inside the wing. There are many ways to do this including tying the plugs together with thread.

A more secure method is to use heat shrink tubing. Cut a small piece of 3/8 in. tubing, available at all electronic supply stores and at many hobby shops, and slip it over the connection (photo 14). Use a modeling plastic film heat gun to shrink the tubing. Don’t burn your hands and do not melt the wires. Once the shrink tubing locks onto the connection (photo 15) it will never come apart.

Photo 15

If you enlarge photo 13, you might notice the Midwest assembly directions in the background. Every assembly step is pictographically detailed in this booklet. As far as could be determined, every single step is covered, some in two or more photos. The booklet contains detailed, photo-illustrated, trimming and flying directions as well. This instruction booklet is the most complete we have seen to date. In fact, it is on a par with the 150-page instruction book designed for the Dave Patrick Extra 330L (Model Aviation, January, 2003) and that instruction manual is designed for serious IMAC competition setups.

 
Photo 16    Photo 17

Midwest also puts a length of string inside each wing half. This string is designed to be tied to the servo wire so it may be pulled through the wing and out the wire exit holes near the wing’s center section (photo 16). Sometimes the string can get caught on a wing rib inside the wing and break. Or it can get caught on a rib and do damage while it is pulled through the wing. Sometimes it is just accidentally removed too soon.

Another way to get the servo lead through the wing is to make a tool out of 1/16 in. music wire available, at any hobby shop. Bend one end as shown in photo 17. Insert the wire through the exit hole near the wing’s center section and push into the aileron servo compartment. Hook it over the servo lead and pull back through the exit hole. If a servo replacement is ever required, you will have to make this tool anyway as the original string will be gone by then. Might as well do it now and be ready for later.

 
Photo 18   Photo 19

Pull the aileron servo lead through the wing and mount the servos in each wing half (photo 18). Midwest provides high quality, name brand hardware such as Du-Bro control horns in their Aerobat kit. Position the aileron control so it is parallel to the aileron’s leading edge and in a straight line from the servo’s control arm’s hole (photo 19). Hint – if you are using a Futaba radio system, position the horn so that it is directly behind the servo arm’s hole that is towards the center of the wing. If using a JR radio system, position the control horn behind the outside hole. Mark the mounting screw holes in the aileron using a pin (photo 18).

The aileron control rods are pre-made and fit perfectly. This is another success feature of the Aerobat kit. Screw on a clevis and connect it to the control horn. You might want to start at the outer most hole (least sensitive) and then adjust for sensitivity after the first few flights. Set the neutral point as discussed in Sport Aviator’s “RTF? … Maybe” article in the Flight Tech Section.

 
Photo 20    Photo 21

The wing is almost done. The last step is to cover the wing’s center section using the supplied center tape that matches the covering (photo 20). After the tape is positioned, use a modeling covering iron to double seal it in place (photo 21).

It is easy to see the two aileron servo leads as they exit the wing near the center section in photo 20. Many new pilots will use a “Y” cord to connect these servos to the receiver’s aileron port. That’s fine and will work well. If an analog radio, non-computer transmitter, is used, then a Y cord is the only installation possible.

But the Aerobat also offers the ability to use the ailerons as “flaperons.” Flaperons, the ailerons can be lowered or raised together to function as spoilers or flaps, provide a lot of maneuver flexibility and amazingly slow landings. When the flaperons are lowered as flaps, the Aerobat just about stands still in the air but is still flying. Coordinating the flaperons with elevator movement, flaps up with “down” elevator and down with “up“ elevator makes for interesting square corners and quick maneuvers. Make sure this option is set if you are using a computer radio. It is too much fun not to use. The radio system’s instructions will detail how to make these settings.

Finishing the Fuselage

So much work is already done for the builder, that there is not much left to do on the fuselage. About the most difficult part is mounting the engine. The Aerobat uses the popular, and easy to use, sliding fiberglass engine mount (photo 22). This mount “self-centers to make sure the engine is positioned correctly all the time. If you have never mounted an engine before, check the “Engines 101 – Part II” article in Sport Aviator’s Pri-Fly Section.

 
Photo 22    Photo 23

We used the powerful and reliable O.S. Max 46 AX engine to take advantage of all the Aerobat’s flight capabilities. This new O.S. engine features a new piston sleeve lining system for extra durability. It also has improved “timing” (see “Engines 101”) for extra power and faster acceleration. This engine proved to be a wise choice and a very good match to the airframe.

The mounting holes in the firewall are predrilled and the mounting nuts already installed. This makes proper engine positioning easy. Before bolting the engine/mount assembly in place, coat the mounting screws with thread locking compound (Photo 23). Make sure to use the kind that allows removal.

The instructions state to use the screws provided (photo 22) and not to use 6-32 bolts. I didn’t do that but used the 6-32 bolts. Why? I have seen several failures using screws, including head separations. Midwest states that using bolts could weaken the mount. In 25 years using fiberglass mounts, including mounting high-horsepower 1.6 cu. in. engines, there has never been a failure. But I can state that the fiberglass mounts will break if thread locking compound is used on the fiberglass beams when mounting the engine. The compound seems to weaken the fiberglass in a short time causing the beam to break at the bolt holes. Since the fiberglass grabs the bolts so tightly, they cannot loosen on their own. Thread locking compound is not required and will cause damage to the mount.

 
Photo 24   Photo 25

Assemble and install the fuel tank before attaching the servo mounting plate. It is easier to slide the tank in and out without the mounting plate’s interference. Assemble the fuel tank. A good way to get an idea of where to cut the internal fuel line is shown in photo 24. Cut just a little longer than measured. Then install the stopper fully into the tank but do not tighten the stopper screw. Make sure the “clunk” is not touching the rear of the fuel tank when holding the tank in the vertical “up” position. If the clunk touches the rear of the tank, the fuel supply will be reduced in a vertical climb causing the engine to run lean or shut down completely. The clunk should be about ¼ in. from the rear of the tank in the vertical position.

Midwest even supplies the fuel line. Install the green line on the fuel draw tubing and run to the engine. The red line, red for hot exhaust, runs to the engine’s pressure muffler. Color coded lines make it difficult, but I still manage to do it, to hook up the pressure line to the engine’s fuel inlet after refueling.

 
Photo 26    Photo 27

Before installing the fuselage servo mounting tray, glue some short pieces of ¼ x ½ in. spruce strips to reinforce the mount’s plywood (photo 26). This provides a very strong gripping surface for the servo mounting screws. The photo shows ½ x ½ in. strips, for photo clarity, but the ¼ in. strips are more than enough. (Actually, I didn’t have any ¼ in. strips in the shop when building the Aerobat so I used the thicker pieces. But they do make for better photos.)

Glue the servo mounting tray into the fuselage, it can only go in one position, using 5-minute epoxy. Then glue some spruce triangle reinforcement strips, using thick CAA, as shown in photo 27. The Aerobat is capable of some wild maneuvers and flies well enough that you will be flying it a lot and for many years. But it is all over if that servo plate pulls loose so reinforce it now for durability. This applies to all ARF and RTF airframes we know. They all use the plywood mounting system and all should be reinforced as shown.

 
Photo 28    Photo 29

After installing the three servos in the fuselage, bend the throttle control rod about as shown in photo 28. This allows the rod to reach the engine’s throttle arm without binding. The amount of bending required depends on engine selection. Slide the throttle arm into the nylon sleeve already mounted in the fuselage. It should look about like photo 29 before connecting to the engine. Connect the control rod to the throttle arm. From inside the fuselage, move the throttle rod by hand to make sure it moves freely. Adjust the bend as required for free movement.

 
Photo 30    Photo 31

The throttle control rod should be about the distance shown in photo 30 from the throttle. Connect the throttle servo arm to the rod using the supplied adjustable link. How to set the throttle position is discussed in “RTF? … Maybe” in the Flight-Tech Section. The last engine installation step is to install the muffler. Put thread locking compound both on the bolt ends and inside the muffler holes (photo 31). This is the only way to insure the muffler stays tight and does not loosen in use.

Installing the Tail Feathers

Photo 32

Unlike any other ARF, except for the Midwest Aero Star 40, the Aerobat’s horizontal stabilizer bolts into place just like a RTF aircraft. The Aerobat uses a plastic reinforcement plate as well. Still, knowing the aerobatics this aircraft is capable of performing, both Midwest and Sport Aviator require the stab to be glued into position with epoxy. The bolts make this easy since they position the stab for you.

 
Photo 33    Photo 34

Bolt the stab in place. Trace the position of the fuselage sides onto the stab covering (lightly, don’t dent the wood) and remove the stabilizer. Carefully cut the covering ONLY about 1/16 in. inside the lines you made (photo 33). Then use a sharp hobby knife to remove the covering overlapping the stab location on the fuselage (photo 34). Removing this covering insures the firmest bond possible as all the wood is in direct contact.

 
Photo 35    Photo 36

Before installing the stabilizer, use a hobby covering “trim” iron to seal the covering’s edges (photo 35). Apply 30-minute epoxy to the fuselage’s stabilizer contact area. Bolt the stabilizer and plastic plate in place. Remove any excess adhesive. Turn the fuselage upside down and level it in a holder. Then put a second, very light level on the stab itself. Use small weights to make sure the stab and the fuselage are perfectly level (photo 36). If the stab is not level to the wings, it will not be possible to make concentric loops. The aircraft will always try to roll with every elevator input. This is not a good thing for aerobatic aircraft to do.

 
Photo 37     Photo 38

After the stabilizer dries, install the pre-made pushrods and control horns. The directions for doing this are fully detailed in the instruction manual. The rudder pushrod requires a slight bend (photo 37) for proper alignment. Once the pushrods are installed, mount the switch in its proper location and install the receiver and flight battery in their positions photo 38). In our test aircraft, the battery was placed under the fuel tank for balance.

Photo 39

The nose gear fits into the engine mount as shown in photo 39. The nylon sleeve for the nose gear steering rod is factory installed and the pushrod is pre-shaped. Just attach a clevis and slide the control rod into position. The main gear bolts into the holes in the fuselage bottom; the mounting nuts are already installed. The axles bolt to the aluminum main gear and use standard wheels collars to hold the wheels in place.

That’s it. We took our time assembling the Aerobat but it was completed in just eight hours 20 minutes. There were no building problems at all. Everything matched, was the right size and went where it was supposed to go without modifications or fitting problems. About the longest assembly step was the radio setup. Using the Aerobat’s flaperons ability, the ailerons were set to drop 30 degrees as flaps. They also moved up to 15 degrees with elevator input.

Flying the Thing

 
Photo 40    Photo 41

The Aerobat’s red and white checker board design is eye-catching. Such complicated designs are rare for an ARF model. The underside of the wing features solid red and blue stripes (see photo 2). It is easy to tell top from bottom once in the air. The fuselage has a very sleek, raked look that looks fast even while sitting on the ground.

Photo 42

The Midwest Aerobat is a fair sized aircraft. The fuselage is 54 in. long with a wingspan over 60 in. The fuselage is about the size of some 60-size trainers. Since the Aerobat is designed as an aerobatic aircraft, the wingspan is only about 85% the size of most 60-size trainers. Midwest compensates for the missing wingspan by using a semi-symmetrical airfoil. As one of the pilots stated during the test flights, “There is a lot of lift in that wing.” (You can hear and see for yourself in one of the video clips.)

Larger model airplanes are a little easier to fly. There is more lift per square inch of wing surface and things happen just a little more slowly. The Aerobat fits into this easier to fly category but is capable of some amazing aerobatics for an aircraft designed as a “second” airplane.

On the ground, the O.S. 46 AX reached top end at 12,600 rpm on an APC 11 x 6 in. propeller. The fuel was Magnum’s 15% nitromethane with 20% oil (15% synthetic; 5% castor). Over the past two years, I have come to trust this fuel for all my 2-cycle sport and competition needs. It provides excellent power and a consistent idle without pushing sport engines too hard.

 
Photo 43    Photo 44

If you compare the photos 43 and 44, you can see that the Aerobat required only about 50 ft. to rotate and lift its wheels. This is pretty good performance for an aerobatic ship on a grass runway with a new engine running a bit on the rich side of the mixture curve. The aerobat was stable and required one click of right trim. All control surface movements were set as per the instructions.

Photo 45

The Aerobat lifted off at 31 mph. This is in the range of the 30-36 mph takeoff speeds recorded for the other high-wing aerobatic trainers we have tested. Climb out was straight and level, with just a bit of right rudder to hold the line, at a respectable 1,400 fpm. As you can see in photo 45, we were not trying for a steep climb on this first takeoff. 1,400 fpm is a good climb rate for such a shallow angle of attack.

 
Photo 46     Photo 47

After takeoff, we circled the Aerobat back over the runway for a few photo passes. The aircraft handled like a trainer. Slow, nose-high flybys were routine. Photo 47 shows the Aerobat at a slightly high nose angle with an idling engine. Handling was definitely trainer like. The airplane remained stable and did not require much elevator to maintain this attitude even at slow airspeeds. If you enlarge the photo, you can see that the elevator is almost at neutral. This is a very good slow-speed aircraft.

 
Photo 48    Photo 49

The next fly-by was done to test the Aerobat’s ability to fly well while held in a forward slip, opposite rudder and ailerons. Many high-wing aircraft have trouble holding a forward slip without constant correction or excessive rudder input. Not the Aerobat though. The flyby was stable and did not need much correction at all. As photo 48 shows, the Aerobat did not need much rudder to hold the slip. Just a hint of “up” elevator was needed to maintain altitude. Flying this aircraft was getting better by the second.

However, the Aerobat is not meant as a basic trainer but rather as an aerobatic one. There was some concern that inverted flight might be more difficult since the Aerobat’s airfoil is not fully symmetrical (usually the best airfoil for inverted work). But we turned it upside down anyway. Inverted flight required about 20% of the available “down” elevator. Frankly, this almost matches both other aerobatic trainers we tested; maybe just a bit more. Inverted flight was not a problem.

Photo 50

If inverted flight was easy, how about a little inverted slip? This attitude is used to enter what can be some very impressive inverted spins. So we did an inverted, forward slipping, flyby (photo 50). Most high-wing aircraft need a lot of piloting attention flying this maneuver so it should be fun. Well, that was pretty boring. The Aerobat was stable, didn’t need much elevator, and just drifted through the maneuver as if it were flying straight, upright and level.

 
Photo 51    Photo 52
 
Photo 53    Photo 54

On the next inverted pass, the Aerobat went into an outside loop from the bottom. The O.S. 46 AX pulled the airplane up into a beautiful outside loop about 250 ft. in diameter. This is near Pattern standards in size. The Aerobat remained steady throughout the maneuver. Neutral elevator was set while going over the top of the inverted loop to make sure it stayed round. The aircraft tracked in the loop so well that the pilot could pay attention to such small finesse things like making the loop truly round.

 
Photo 55     Photo 56

Next, we tried some rolls. The Aerobat’s roll rate is a bit fast for first time aerobatic pilots when set on the factory settings. The instruction book says to connect the aileron control rod clevis to the second hole from the top in the aileron control horn. Beginning aerobatic pilots might want to use the hole furthest from the wing instead. The slower roll rate remains good, but allows the very new aerobatic pilot a bit more time to input down elevator during the inverted roll portion. Triple rolls were no problem nor were slow rolls and point rolls.

While there is some roll coupling with rudder input, the aircraft rolls slightly when rudder only is applied, it is not excessive. In fact, the Aerobat’s roll coupling is a minor distraction and does not hinder aerobatic maneuvering as much as happens in some other aircraft. All high-wing aircraft tend to “pull” toward the wheels in knife-edge flight when using the rudder to maintain altitude. The Aerobat is no exception.

But happily, the pull is not excessive and could actually be corrected using small “up” elevator input. Most other high-wing aircraft pull so hard that it is nearly impossible for the pilot to keep a straight line. But the Aerobat can with a little work. The Aerobat also can maintain altitude while in knife-edge flight if it has a powerful engine like the O.S. 46 AX. This is another unusual feature in a high-wing aerobatic trainer. The rudder is powerful, but still feels light on the controls. That is, the rudder is very effective but does not adversely affect much of the aircraft’s other flight abilities.

How powerful is the O.S. 46 AX and Aerobat combination? As shown in the videos, it was hard to slow the Aerobat down to its 45 mph best training speed. Only about one-quarter throttle was needed to cruise at 45 mph. Full power climbs averaged an impressive 2,800 fpm. One climb topped out at 3,300 fpm. For second aircraft and trainers, this performance approaches warp capabilities, Mr. Sulu.

 
Photo 57     Photo 58

As much as the powerful engine, the Aerobat’s wing adds to its great climb performance. There is a lot of glide in this aircraft as the Aerobat’s descent rate is just 900 fpm at 40 mph. This is good for an aerobatic trainer. When added to its clean airframe, this low descent rate means the Aerobat can glide a distance of 1,600 feet if the engine quits 400 ft. high. That is a long glide distance for an aerobatic trainer. For comparison purposes, a fully aerobatic Pattern Airplane glides about 3,000 ft. from the same altitude while a large scale aerobatic aircraft will glide about 800 ft.

 
Photo 59    Photo 60

The Aerobat’s excellent glide performance translates into those pretty, nose-high landings we all dream about but can never seem to make happen. Using attitude to control airspeed is easy. The Aerobat slows dramatically when that big wing is raised into the airflow. Similarly, the airplane quickly picks up speed when the nose is lowered. New pilots will be able to learn how to land all advanced aircraft using the Aerobat. Yet the airplane also can land like the basic trainer they are used to flying.

 
Photo 61     Photo 62

All the flight tests up to now were performed without using the flaperons. Many new pilots, especially those transitioning from most RTF trainers, do not have computer transmitters. Even some new pilots who do own these more advanced transmitters prefer not to use some of their advanced capabilities. So testing without the flaperons or mixed elevator/flaperons controls is only fair.

But what happens when those flaperons are lowered? The Aerobat slows dramatically once the flaperons are deployed. The aircraft remains stable but approach speeds drop to under 20 mph. The descent rate also increases. Photo 61 shows the Aerobat in slow, flaperons deployed, flight. It is flying at about 25 mph at about one-third throttle. Use half-throttle and the Aerobat can almost stand still in the air while maintaining altitude.

Photo 62 pictures just how far the Aerobat can be pushed. (As editor, I must apologize for the poor photo here. Sport Aviator uses 35 mm film for flying photos so we were not aware of the poor focus. But the picture is so impressive that we included it anyway and will substitute a new one as soon as it can be taken.) This photo, the only close to usable one in a whole sting, was at the end of a flyby, not a landing approach. The Aerobat flew the entire length of the field at this high angle of attack. It was stable and easy to control. The wing never tried to drop off to one side and the nose angle was maintained using about 50% power. This is what flying a well-designed high lift airframe mated to a powerful, reliable engine is all about.

 
Photo 63    Photo 64

We threw the Aerobat around the sky doing snap rolls, gentle but true snaps, stall turns, positive with only a slight roll tendency easily corrected and spins. The spins were gentle with a slow rotation. Recovery was easy. Just release the sticks and the Aerobat recovers itself. After the rotation stops, adding a little “up” elevator returns the aircraft to normal flight.

Midwest also manufacturers the Aero Star 40 basic trainer. This aircraft is also reviewed in Sport Aviator by Eric Henderson. Eric competes in F3A Precision Aerobatic competition (called the FAI Class), unlike your lowly editor who only competes in the Masters Class (the next class down). Eric just couldn’t resist the temptation to fly the Aerobat and compare it to his Aero Star 40. The separate section below is Eric’s impressions of the Aerobat.

The Midwest Aerobat is truly an excellent second aircraft. The ability to use flaperons and coupled elevator/flaperons settings offers a wide range of flight capabilities. Its slow speed handling makes it a joy to fly and safe for even the aerobatic novice. The Aerobat could function as a basic trainer but it can be very fast with the highest top speed we have ever recorded, over 75 mph. If you intend to use the Aerobat as a basic trainer, keep that throttle well below the half way point.

I like this airframe a lot. I think most pilots looking for that second airplane, one more capable than their basic trainer but resembling the trainer’s flight characteristics, will like it just as well. The Aerobat is a bit fast for a basic trainer but its great slow speed handling and high-lift wing would allow it to function as one. The Aerobat’s over 75 mph top speed and 38 mph approach speed does require faster piloting decisions than do most basic trainers. Still, with a tender hand on the throttle, the Aerobat could take a pilot from nothing to aerobatic fun by itself if necessary. But the Aerobat simply excels as the new pilot’s second airplane, opening the door to advanced RC flight.

 

The Midwest Aerobat is the lowest priced ARF second aircraft tested so far. The Aerobat’s pricing starts under $90 for the complete kit. For more information, go to the http://www.falcon-trading.com/product.cfm?prodID=6

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MIDWEST AEROBAT – Flight Testing  by Eric Henderson The previously reported test flying of the Midwest Aero-Star 40 trainer ended with a plea to the Sport Aviator editor, Frank Granelli, to have a crack at the AEROBAT. Of course “rank has its privileges” so Frank kept it for himself, but I did get one crumb and was invited to do some of the test flying. We all met in the Pocono Mountains on a sunny but autumn-cool and, of course, windy day. The wing was attached just like the Aerobat’s trainer cousin with rubber bands. Frank had the honors of the first flight. The OS46 AX ran perfectly and we did not need a full tank before we were ready for flight. Seeing as how I was relegated to being a spectator I filled in the time with the digital video camera. Soon it was my turn; I fly Mode-1 (Throttle and elevator on the left, ailerons and throttle on the right). We could not copy the programs because Frank’s radio had digital trims and mine did not. So we hooked up my JR 8103 with Frank’s 8103 using the JR buddy lead. We soon had it programmed and did a quick test flight. Then I put Frank’s Transmitter frequency module into my Transmitter and I was “free from the trainer wheels”, so to speak! The plane was given a taxi test to ensure that it tracked well and would in fact turn. All controls were double inspected for orientation and direction. With everything checked out we were at that moment where there are no excuses left! Advancing the throttle with elevator at neutral caused the plane to accelerate briskly. After about fifty feet the elevator was applied and the AEROBAT leapt into the air. I planned to try all of the maneuvers that I subjected the AERO-STAR-40 to, but I had a bit of fun first, just to make “Mr. Granelli” nervous. I think the slow-roll very soon after take-off had him holding his breath? Here is how the AEROBAT stacked up against its little cousin! The plane is called an AEROBAT so aerobat it we would. Loops were easy and straight either way up. The loops could be tight or big and round. I performed multiple consecutive loops switching to inverted when going over the top without any problems at all. Rolls were where the AEROBAT was in its element. You could add a small amount of rudder as the plane goes through the knife-edge attitudes. There was still some rudder effect on the roll. This is to be expected with a shoulder wing plane. A slow-roll could be made to look very good indeed. Stall-turns (Hammerheads) were possible with a little rudder. Too much rudder will cause the plane to roll a little as it comes off the top. Spins were easy to do and stopped rotating almost as soon as you returned the sticks to their centers. It will snap-roll either way up but that seemed to cause groans from the editor who mentioned, more than once, that there perhaps should be more rubber bands on the wing. [I have to say that he was right. It did turn out that the rubber-bands lost some strength/memory in the cold air - so be safe and add a few more than you need on cold days.] The plane was easier to land than the trainer. It just stuck to the runway. Oh, did I mention that it was windy. The plane flew so well and felt so “locked” that the wind was not really a factor. I would go so far as to say that you could compete with this plane, at least in the first two AMA Precision Aerobatic classes. In conclusion, the Aero-Star-40 is a trainer; the AEROBAT is an Aerobatic trainer. It is not a trainer that does Aerobatics. It will allow you to teach yourself the main roll and loop maneuvers. I was surprised how well it flew!

Flight Data Results* *Take Off Speed: 31 mph Climb Out Speed: 40 mph Best Training Speed: 45 mph Top Speed: 75+ mph Sustained Climb Rate: 2,800 fpm Range: 18-22 minutes Dive Speed: 75+ mph Best Glide Speed: 40 mph Gliding Descent Rate: 900 fpm 400’ Glide Distance: 1,600 ft. Level Stall Speed: 20 mph 60-deg. Bank Stall Speed: 28 mph Landing App. Speed: 38-40 mph Touch Down Speed: 28 mph *All results are an average of 3 flight tests Aircraft Specifications Type: Aerobatic Trainer Engine Used: O.S. Max 46 AX Propeller: APC 11 x 6 in. Top RPM: 12,600 rpm Idle RPM: 2,200 rpm Test Weight: 5 lb. 15 oz. CG Location: 3.1 in. back from L.E. Elevator Movement: 3/4 in. Aileron Movement: 3/4 in. Rudder Movement: 1.5 in. Weather Data Temp         Wind          Alt. 45 deg. F   10-15mph    300 ft.

AIRCRAFT SPECIFICATIONS Manufacturer: Midwest Length: 54.5 in. Cost: $125.00 Wingspan: 60.5 in. Radio: JR 8103 Wing Area: 660 sq. in. Servos: 5 x JR 537 Wing Loading: 20.7 oz./sq. ft. Engine: O.S. Max 46 AX Weight: 5.94 lb. Airfoil: Semi-Symmetrical Special Airframe Features: Semi-Symmetrical Wing, Easy, Quick assembly – more complete than most ARF kits. Factory installed vertical fin, bolt-on stabilizer

Notable Positives Excellent aerobatic abilities Great knife edge ability Flaperon versatility Extremely fast assembly Very good looks Light flying weight Very low cost High quality construction & accessories Notable Negatives Very fast for a trainer

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