CGS Aviation Makes Hawk

HIRTH POWER – CGS Aviation has maintained support for the Hirth 2-cycle engines. This dual-ignition 2702 model ran smoothly and gave the Ultra plenty of power. Note cargo door.

MAIN BOOM – When the main boom gets this far forward its function allows the lightening holes used everywhere on the Ultra to keep weight down.

GROUND DOWN – No, these aren’t old worn-out tires. They’re brand-new but Chuck laboriously ground off the rubber to lessen their weight.

TAIL VOLUME – Many experts see too-small tails as a big handling problem. The Ultra uses the general tail volume common to Hawks to provide excellent handling.

TINY WHEEL – The Ultra uses a skateboard wheel for a tailwheel. Even in sandy soil it worked very well.

AFT VIEW – Lightening holes placed in the aft structural plate yield some view to the rear, though you can’t turn this far in your seat. The area forward of that bulkhead can be used for some cargo.

BIG FLAPS – Even while meeting a tough weight limit, the Ultra is able to have flaps that help landings.

RED HANDLES – On either side of the pilot’s head are two handles (arrows). On his left is the flap; on the right is the parachute handle. The parachute pack is seen aft of the silver lateral members.

Remember why we fly ultralights? Few general aviation airplanes are flown below 1,500 feet above the ground. More rare is flight at 500 feet or 50 feet. Neither do you tend to fly most light-sport aircraft (LSAs) at these denser altitudes. Most flights in general aviation or LSA planes start out climbing high as quickly as possible. You switch on the autopilot as soon as possible and fiddle with the throttle, prop and mixture controls to squeeze all the fuel economy you can while flying as fast as the machine will manage in the straightest possible line all the way to your destination.
That’s fine for general aviation or LSA flying, and it’s enjoyable in a different way. But it isn’t ultralight flying.
What about just “boating around” the sky at your leisure, turning every few minutes to see the sights only possible from an ultralight aircraft. Your eye catches an alligator off to one side and you bank quickly to check it out. You drop down from “nosebleed height” – pattern altitude perhaps – to a proper ultralight altitude of a couple hundred feet where you observe the prehistoric creature catching the Florida sunshine. Ah, this is what I call flying!
So, throttle back, ease aft on the stick as speed decreases, deploy a couple notches of flaps and finally bring back in a little power. You’ve transformed a good cruising Hawk Ultra into a superior low-over-the-fields flyer. Ultralights hardly need altimeters given their common use below 1,000 feet above ground level (agl). But their real charm comes when you fly 20 to 200 feet over unobstructed fields. If you’ve been locked up inside your 120-knot LSA too long, you deserve a flight in a Hawk Ultra so you can get low and slow. Wandering below the treetops at 40 mph is a special experience – and it’s best done in a vehicle like the Hawk Ultra.

“Ultra” Really Means Ultralight
Many ultralights may be very light aircraft and ultralightlike in their construction, but they simply aren’t the magical 254-pound ultralights. No 2-seater is a true
ultralight. The only “real McCoy” is the single-seater that meets FAA’s simplest rule, FAR Part 103. No pilot’s certificate nor medical required. No federal registration. Fully built is okay and prices are typically what the rest of us can afford.
Given these striking advantages, why aren’t more Part 103-compliant airplanes sold? Well, quite a few are sold. Many trikes, nearly all powered paragliders, and all unpowered (or powered) hang gliders count. In the USA, that amounts to well over 1,000 units sold every year.

“But you can’t buy an honest fixed-wing Part 103 ultralight, at least with a decent engine on it,” is a common retort.
I’ve long said, “Wrong!” If you build carefully and don’t insist on unnecessary accessories, these airplanes can make Part 103 requirements and still perform well. Some manufacturers are willing to fully build a Part 103-compliant ultralight, though this raises the price tag considerably.
My insistence about availability of fixed-wing Part 103 designs hasn’t mattered. People want more utility and gravitate to 2-seaters with electric starters, 4-stroke engines, and all manner of gear that raise the weight far beyond what was envisioned in Part 103. But the regulatory burdens for Light-Sport Aircraft may be renewing interest in genuine Part 103 ultralights. Randy Schlitter of RANS admits to being intrigued by meeting the challenge. He may design another Part 103 model as he’s done before. Chuck Slusarcyzk of CGS Aviation is another pioneer who’s heard the call.
Chuck said a high ratio of the calls he’s been getting lately – he mentioned a figure of 10 to 1 – were for Part 103-compliant aircraft. Given this level of interest, Chuck chose to pursue a meet-the-definition Hawk, which he calls the “Ultra.”
Chuck pulled out all the stops, and did everything he could to cut excess weight. He said, “Not a part went on the airplane without an effort to reduce its weight,” while still allowing for adequate safety margins. You can see this in the photos. Everything you look at has holes in it. Each one had to be cut or punched, representing extra work. An interesting Part 103 aircraft may be more expensive not less, but if you fly under Part 103, you won’t have as many federal regulations in your flying pursuit. That’s still very cool.
Everything Counts
Chuck worked hard to make the Ultra. Serial production of enough Ultras could lessen the effort significantly, but it can still be rather costly to produce a very weight-conscious aircraft design. For his effort, Chuck accomplished a lot: fully enclosed, 3-axis control, twin-cylinder dual-ignition engine, and flaps. He also added an emergency parachute, though this addition actually gains allowable weight for the ultralight. FAA has always allowed 24 additional pounds, even if a system can be built with less weight. With an emergency parachute, a Part 103-compliant ultralight can weigh 278 pounds
empty.

The Ultra forgoes trim in the interest of saving weight. Indeed, the test Ultra had a nose-up tendency for me during all flight operations and trim might have been nice. But the feature wouldn’t fit under Part 103’s weight what with the Hawk Ultra already tightly up against the limit. To fly under FAA’s least intrusive rule, you have to give up some “luxuries.” Fortunately, stick pressures are light enough in the Ultra that the lack of trim was really no problem.
The Ultra’s seat belts attached to the side rails of the cockpit at a point not much below my hips. Tightening those belts did not tend to snug me down in the seat. Still, the belts were adequately secure and on a larger occupant they would likely grip more tightly.
In classic ultralight style – using simple techniques to hold weight down – you increase ventilation in this fully enclosed cockpit by opening the door zippers at the top corner, up by your eyebrows. A supply of fresh air enters the cockpit and it can be increased or decreased easily.
Fabric enclosures lack the durability of harder surfaces. A tear had already started on this new model where the engine starter rope came in contact with the fuselage cover. Chuck plans to add a pulley to the starter rope so you can pull forward toward the cabin. On the test Ultra, you had to pull straight out to avoid tearing the
 
emember why we fly ultralights? Few general aviation airplanes are flown below 1,500 feet above the ground. More rare is flight at 500 feet or 50 feet. Neither do you tend to fly most light-sport aircraft (LSAs) at these denser altitudes. Most flights in general aviation or LSA planes start out climbing high as quickly as possible. You switch on the autopilot as soon as possible and fiddle with the throttle, prop and mixture controls to squeeze all the fuel economy you can while flying as fast as the machine will manage in the straightest possible line all the way to your destination.
That’s fine for general aviation or LSA flying, and it’s enjoyable in a different way. But it isn’t ultralight flying.
What about just “boating around” the sky at your leisure, turning every few minutes to see the sights only possible from an ultralight aircraft. Your eye catches an alligator off to one side and you bank quickly to check it out. You drop down from “nosebleed height” – pattern altitude perhaps – to a proper ultralight altitude of a couple hundred feet where you observe the prehistoric creature catching the Florida sunshine. Ah, this is what I call flying!

So, throttle back, ease aft on the stick as speed decreases, deploy a couple notches of flaps and finally bring back in a little power. You’ve transformed a good cruising Hawk Ultra into a superior low-over-the-fields flyer. Ultralights hardly need altimeters given their common use below 1,000 feet above ground level (agl). But their real charm comes when you fly 20 to 200 feet over unobstructed fields. If you’ve been locked up inside your 120-knot LSA too long, you deserve a flight in a Hawk Ultra so you can get low and slow. Wandering below the treetops at 40 mph is a special experience – and it’s best done in a vehicle like the Hawk Ultra.
“Ultra” Really Means Ultralight
Many ultralights may be very light aircraft and ultralightlike in their construction, but they simply aren’t the magical 254-pound ultralights. No 2-seater is a true
ultralight. The only “real McCoy” is the single-seater that meets FAA’s simplest rule, FAR Part 103. No pilot’s certificate nor medical required. No federal registration. Fully built is okay and prices are typically what the rest of us can afford.
Given these striking advantages, why aren’t more Part 103-compliant airplanes sold? Well, quite a few are sold. Many trikes, nearly all powered paragliders, and all unpowered (or powered) hang gliders count. In the USA, that amounts to well over 1,000 units sold every year.
“But you can’t buy an honest fixed-wing Part 103 ultralight, at least with a decent engine on it,” is a common retort.
I’ve long said, “Wrong!” If you build carefully and don’t insist on unnecessary accessories, these airplanes can make Part 103 requirements and still perform well. Some manufacturers are willing to fully build a Part 103-compliant ultralight, though this raises the price tag considerably.
My insistence about availability of fixed-wing Part 103 designs hasn’t mattered. People want more utility and gravitate to 2-seaters with electric starters, 4-stroke engines, and all manner of gear that raise the weight far beyond what was envisioned in Part 103. But the regulatory burdens for Light-Sport Aircraft may be renewing interest in genuine Part 103 ultralights. Randy Schlitter of RANS admits to being intrigued by meeting the challenge. He may design another Part 103 model as he’s done before. Chuck Slusarcyzk of CGS Aviation is another pioneer who’s heard the call.

Chuck said a high ratio of the calls he’s been getting lately – he mentioned a figure of 10 to 1 – were for Part 103-compliant aircraft. Given this level of interest, Chuck chose to pursue a meet-the-definition Hawk, which he calls the “Ultra.”
Chuck pulled out all the stops, and did everything he could to cut excess weight. He said, “Not a part went on the airplane without an effort to reduce its weight,” while still allowing for adequate safety margins. You can see this in the photos. Everything you look at has holes in it. Each one had to be cut or punched, representing extra work. An interesting Part 103 aircraft may be more expensive not less, but if you fly under Part 103, you won’t have as many federal regulations in your flying pursuit. That’s still very cool.
Everything Counts
Chuck worked hard to make the Ultra. Serial production of enough Ultras could lessen the effort significantly, but it can still be rather costly to produce a very weight-conscious aircraft design. For his effort, Chuck accomplished a lot: fully enclosed, 3-axis control, twin-cylinder dual-ignition engine, and flaps. He also added an emergency parachute, though this addition actually gains allowable weight for the ultralight. FAA has always allowed 24 additional pounds, even if a system can be built with less weight. With an emergency parachute, a Part 103-compliant ultralight can weigh 278 pounds empty.
The Ultra forgoes trim in the interest of saving weight. Indeed, the test Ultra had a nose-up tendency for me during all flight operations and trim might have been nice. But the feature wouldn’t fit under Part 103’s weight what with the Hawk Ultra already tightly up against the limit. To fly under FAA’s least intrusive rule, you have to give up some “luxuries.” Fortunately, stick pressures are light enough in the Ultra that the lack of trim was really no problem.
The Ultra’s seat belts attached to the side rails of the cockpit at a point not much below my hips. Tightening those belts did not tend to snug me down in the seat. Still, the belts were adequately secure and on a larger occupant they would likely grip more tightly.
In classic ultralight style – using simple techniques to hold weight down – you increase ventilation in this fully enclosed cockpit by opening the door zippers at the top corner, up by your eyebrows. A supply of fresh air enters the cockpit and it can be increased or decreased easily.
Fabric enclosures lack the durability of harder surfaces. A tear had already started on this new model where the engine starter rope came in contact with the fuselage cover. Chuck plans to add a pulley to the starter rope so you can pull forward toward the cabin. On the test Ultra, you had to pull straight out to avoid tearing the fabric and this did not allow enough distance from the prop for my taste. Even a pulley adds weight, however, and must be considered carefully.

Continuing the weight watch, the Hawk Ultra has no brakes. Genuine ultralights are so light that braking is hardly needed except on hard surface airport ramps.
Even on the sandy soil turf runway the Ultra’s tiny skateboard tailwheel proved to offer authoritative steering. The little Hawk’s turn radius was small and turning was quite effective at just below landing speeds.
Weighs Less, Flies Great
All the Hawks have won my admiration for their good handling. It’s not only my feeling; I’ve heard this from dozens of Hawk owners over the years. And though some poundage was lost on the Hawk Ultra, the handling may have actually improved. So did performance.
The Hawk with all the holes in it jumped off the ground when pushed enthusiastically by the 40-hp, twin-cylinder, dual-ignition Hirth 2702 2-cycle engine. The tail came up almost immediately and the Ultra left the ground shortly thereafter. Taildragger takeoffs are very straightforward when they’re as easy as the Ultra’s.
Hawk aficionado and airline jockey Grant Smith calls the Ultra’s legs “ultralight landing gear,” by which I realized he meant not as stout as on the heavier Hawks. It’s all part of the weight reduction program but losing weight brings benefits. All the parts can be lighter without compromising structural integrity.
Being a Part 103-compliant ultralight, the Ultra is a single-seater. Before a pilot report flight I always have accepted anything the checkout pilot wanted to tell me, even when aircraft are very simple like the Ultra. Used to good cockpit procedures, Smith offered me his usual detail.
Smith recommended I approach at 45 to 50 mph. You could come in slower but you don’t have much energy reserve for flare to landing. Again, light aircraft generate less kinetic energy, which in turn gives them a noticeably shorter roll-out – part of why brakes are not really needed.

Despite the diet, the Ultra comes with Hawk flaps, although even the flap handle has holes in it to reduce a few ounces. They are needed on landing to create lift at slower speeds and they rise to the need effectively.
Slips to landing worked very well in either direction. The Hawk Ultra will allow you to set up a highly angled slip that really pulls you out of the sky. You have good flaps, so you don’t need much slip, but the slip potential was significant enough that I speculated CGS Aviation might consider eliminating the flaps to save more of those precious ounces. Contrarily, the flaps might prove useful on takeoffs from short or soft runways where slips are of no help.
The distillation of the flap and slip discussion is that the Hawk Ultra can operate rather successfully from very short strips. I had to watch my performance takeoffs, though.
Maximum temperature on the CHT was not to exceed 525°. The Grand Rapids Technologies Engine Information System (EIS) alerts you to programmed settings and this one went off without too long a sustained climb. It recovered quickly but I felt it was something to monitor.
Because the EIS alert came on after only 500 feet of climb (as Smith had told me it would), I was unable to perform a long time-to-climb measurement. This is a free-air-cooled Hirth; for the familiar reason of weight reduction it couldn’t offer the same temperature control as a liquid-cooled powerplant.
I sampled another en route climb trial at 5,200 rpm and 60 mph where a liberal amount of airflow through the engine is assured. The resulting ascent was reasonably enthusiastic. However, even at this setting (300 below max rpm), the heat alert warning light finally lit.
On all these heat observations I noted that when the alert light went off and the temperature again appeared, the number would typically drop quickly to a more acceptable 425° to 460° depending on how quickly I got off the power and to what extent I reduced throttle.
I happened across the en route climb solution for the Ultra when, at a power setting just above 4,700 rpm, I found I’d gained several hundred feet. I realized you could stay with a modest power setting, don’t raise the nose too high, and the Ultra with Hirth 2702 will climb relatively well without overheating the engine. It’s all part of the process of operating an aircraft on a serious diet.

Sweet Hawk Handling
Fortunately, all the work Chuck did to make Part 103’s tight restrictions did not change the excellent flying qualities of the Hawk Ultra. In fact, I think it aids handling to lose weight. I’ve flown every variation of the Hawk over the years and every single one of them flew well. But my single-place bias shows and I prefer this Ultra to some of the Hawk 2-seaters.
This Ultra had a modest left-turn tendency. This kept me on the right rudder nearly all the time to keep the plane from straying to the left. What seemed a P-factor influence in climb continued in level flight with power reduced; the left turn remained. Of course, an owner would add a fixed tab and work with it until the problem disappears. Another alternative might be small adjustments in the aileron rigging. The left-turn tendency required me to apply the right rudder pedal liberally in right turns, or I tended to slip.
The Ultra’s control stick in the neutral position was approximately at my knees, a little farther out than I would have preferred. A friction lock would have been handy for the throttle. It tended to creep toward idle thrust when I removed my hand from the control, though the motion was delayed and didn’t present much problem. At a cruise setting of 4,720 rpm, the throttle tended not to move much. But a friction lock adds weight.
To boost performance, I found I could use thermals for climbing as a soaring-experienced pilot could feel them quite readily in this very light aircraft.
Smith had advised me that 4,800 rpm was a good operating number for the Hirth 2702 powerplant. I found even less was plenty and at 4,720 rpm, I recorded a speed of 65 mph.
With the Hirth at full throttle, the maximum revolutions showed a shade over 5,500 rpm, at which setting the installed ASI read about 70 mph. This is more than the 63 mph allowed, but I was told Hirth does not advise running continuously at this setting. At the maximum allowed continuous power setting, speeds are likely to remain within Part 103’s 55-knot (63-mph) speed limit. I kept experimenting with different power settings.
At only 4,000 rpm, the Ultra was close to holding altitude and the cabin was reasonably quiet and smooth. At 4,500 rpm I could gain altitude quite steadily without setting off the EIS heat alert light. I recorded a climb of 300 feet in a couple minutes, so it wasn’t a fast climb but it kept the Hirth at a temperature it preferred. This lower power setting also reduces fuel burn somewhat, and noise and vibration are enjoyably low.

After only a few minutes’ experience in the Hawk Ultra I could just about hold altitude in level flight with barely over 4,000 rpm. At that setting I was losing a few feet per minute, but not many. A setting of 4,200 rpm seemed to neutralize altitude loss with this Hirth engine on this particular Ultra.
Some will note my efforts at efficiency were on an aircraft without wheel pants or streamlined struts. You’ll find no faired tubing on this Ultra, again to keep the weight down.
This first Ultra was using a composite prop. A wood prop is needed to save weight, but the composite version will allow CGS to determine the correct pitch to achieve maximum performance. Once Chuck determines the right amount of prop pitch, he plans to select a wood prop with the optimal dimensions.
The Hawk Ultra displayed low-power stalls that never break; you merely note a sinking sensation identified with this flight condition. During my stall practice the ASI read about 30 mph, a range where such instruments are prone to error.
Simulated departure stalls at about 5,000 rpm also did not break but showed more of a tendency to do so. Because of the heating issues, I didn’t take the opportunity to try full-power stalls.
I did evaluate dynamic longitudinal stability of the Ultra. Adding full power resulted in a modest nose-over – no surprise given the relatively high thrust line. Conversely, backing off on the power didn’t lower the nose much but this Hawk Ultra had a bit of nose-up tendency at all times in flight.
(Almost) Regulation-Free
The magic of Part 103 is that you can fly a light sporty aircraft without a lot of regulatory hassles. What no one knows is the future for growth in genuine Part 103 ultralights now that Sport Pilot and Light-Sport Aircraft are here. But it’s been such a long and successful run for the Hawk that I believe the Ultra is likely to proliferate.
More than 1,600 Hawks have been built so far. Given a 23-year production run, that translates to about 70 Hawks a year on average, quite a good lifetime performance.
CGS Aviation has long offered a wide variety of engines from Hirth, Rotax, HKS and others. Given pilots’ interest in powerplants, this choice has probably stimulated demand over the years.
Chuck Slusarczyk said the 40-hp Kawasaki 440A 2-cycle engine is a distinct possibility and would save a whopping 20 pounds over the 91 installed pounds of this Hirth 2702 (counting its reduction drive and exhaust). Chuck thought the Kawasaki 440s were in ample supply and my experience with this engine on the early Flightstar and JetWing trikes reminded me how satisfied I was with that engine. These numbers are without prop so the change to a lighter wood prop does not affect this analysis. With the Kawasaki 440 you could have brakes and electric start, which would make that engine a most attractive option.
Another engine is coming that might also work – a 4-stroke Jabiru. Well known for the 2200 and 3300 4- and 6-cylinder powerplants widely used on LSA, Jabiru plans to offer an 1100 model with two cylinders. According to Jabiru USA, this engine will offer 45 hp at 85 pounds. If these numbers are achieved and the price is reasonable, Hawk Ultras might try to go 4-stroke. The Jabiru 1100 is essentially the same weight as a Rotax 447 (but with more power), so you’d still have to build the Hawk Ultra very carefully. But it might be possible to make Part 103’s 254-pound weight limit with a powerful 4-stroke engine and this may be exciting to some buyers.
A Hawk Ultra kit starts at under $9,000. By the time you’re done building a plane like our test bird, you’ll have $15,000 invested. CGS Aviation has a wide assortment of accessories you can use to bid up the price, but as soon as you start adding gear, you’ll push the Ultra out of the Part 103 definitions.
A Hawk Ultra for well under the price of an average new car seems a bargain. And she’s so much fun to fly, and so unburdened by FAA regulation and oversight that I believe the Ultra will find a consistent market for CGS Aviation.