congratulations to Petr Starek flying HpH Glasflugel 304C
European 2004 Barron Hilton Cup winner- longest declared FAI triangle in Europe, Standard class
Notes from our friends "down under"
Hello Jaroslav
I have just returned from our Easter Competitions at Dalby in Queensland. We took both hph 304c’s to these competitions and the response was very good. At the competitions Andrew Georgensen and Tom Claffey who are both members of the Australian team for the next World Championships flew the 304c’s as part of the Easter competition. They are preparing a written report for me to publish. Andrew placed 8th on the day but was hindered by the failure of the Cambridge 302 (no electronic vario) and an embarrassing re-launch for a toilet stop. He was very impressed with all facets of the aircraft. Andrew is a big man and some tail weight would have been his only request to move the cofg slightly back. Andrew flew 369km at 112kph!
By the trace Tom was actually winning the final day of the competition flying ZAI in partnership with his own Discus. The day was very “blue” with no cloud and a weather system which collapsed 30 km from home after a 270km flight in 150 minutes. Both Tom and the Discus outlanded 30 km from the finish line very disappointed. Tom was sceptical of the 304c’s performance before he left – but not any more!!
These comps are done as AAT’s and on handicap. There were 61 gliders flying on Andrew’s day and 51 with Tom. There was everything from 4DM’s down to Standard Libelle’s. On Andrew’s day he beat every LS8 (of which he owns one - GAG) and was only beaten by Open Class gliders.
I only got 1 flight in ZAI!! But I achieved a personal best and was happy to make it home.
Regards
Rob Izatt
HPH Australia
A FLIGHT TEST EVALUATION OF THE HpH 304C WASP STANDARD CLASS SAILPLANE
Richard H. Johnson 12/30/02
INTRODUCTION
The HpH 304C Wasp is a new 15-meter Standard Class sailplane that was recently derived from the popular Glasflugel 304CZ 15/17.43 meter wingspan flapped sailplane, and currently in production in the Czech Republic by the sailplane manufacturer HpH Ltd (Ref. A).
When HpH Ltd took over production of the Glasflugel 304, they introduced the 304CZ, and added winglets to the design. They also extended the 304’s wing span to 17.43 meters. Their latest introduction is the 304C Standard Class sailplane, popularly called the Wasp. A total of 62 sailplanes have now been produced, with over 50 making their way to new owners in the USA. This combined with the original 304’s produced by the Glasflugel company brings the total number of this series of 304 sailplanes to nearly 130.
Its modification to a Standard Class sailplane consisted mainly in limiting its wingspan to 15 meters, removing its wing trailing edge flaps, and changing the wing airfoil to a more cambered one. Also, its wing trailing edge airbrake design was replaced with the less complicated and expensive wing top surface Schempp-Hirth airbrake design. By limiting the wingspan to 15 meters and simplifying the wing design achieved a weight savings of about 10 lbs per wing panel. These design modifications were principally the work of HpH engineer Jiri Hodan.
The Wasp is of a conventional modern Standard Class sailplane configuration, and its control systems and operations are uncomplicated, making it relatively easy to fly. The workmanship and detail design of our test sailplane was outstandingly good. Its Vorgelat gel-coated exterior surfaces were beautifully smoothed, polished, and waxed. The wing area is about 106.5 square feet, and its aspect ratio measures about 22.7. Its wing airfoil is reported to be a modified HQ 014-1642 design. It has more camber than the 304CZ’s HQ 010-1642 airfoil, to improve the Wasp’s low speed and climb performance. Figure 1 is a 3-view of this excellent new all fiberglass composite sailplane.
The 304C Wasp has now been in production for about one year, and it already has received a FAA Standard Type Certificate. We were fortunate in that a member of the Dallas Gliding Association, Andre deBaghy, decided to purchase serial number 55-C, and kindly allowed Dean Carswell and me to use his sailplane for flight testing and evaluation. We made a detailed inspection of this sailplane, and were both impressed with its workmanship and very good quality. The wing surface waviness was very low, averaging well below the .004inch limit that I believe to be needed to achieve extensive low drag laminar flow on sailplane wings. Its epoxy/glass fiber composite construction appeared to be quite strong, and its empty weight fully equipped with factory winglets, instruments, and a large battery was about 598 lbs. The details of its construction were very well done. All of the exposed metal fittings were nicely cadmium plated for enduring rust protection. Its retractable main wheel is a well-sized 5.00 x 5-inch Tost unit that is equipped with a standard drum brake, which functioned well. The aft end of the fuselage is equipped with a standard 210x65 mm pneumatic tail wheel. A nose towhook was installed in our test sailplane that made aero towing very easy.
AIRSPEED CALIBRATION
The Wasp airspeed system uses a tail fin mounted pitot and aft fuselage sides for its static source. First we checked the pitot and static system lines for leaks, and found none. Then, while inside the hangar and out of the wind, we calibrated the sailplane’s Winter airspeed indicator by carefully comparing its readings to our calibrated reference ASI meter. The errors that we measured for the sailplane’s Winter ASI were outstandingly low, less than about a half knot over our entire planned flight test range! Those measured airspeed indicator instrument error data are shown in Figure 2.
We then began our airspeed system flight calibration. A 9,000 foot high tow was then made with the sailplane equipped with a trailing bomb static reference, deployed in flight after tow release, and a Kiel tube reference pitot temporarily taped to one side of the canopy. The flight test calibration was then steadily flown at indicated airspeeds of 40 to 120 kts, comparing our master reference indicated airspeeds to those of the sailplane’s. Those test data were then used to compute the Wasp’s airspeed system errors versus indicated airspeed. The Figure 3 chart presents the flight measured ASI System errors. The Wasp’s airspeed system errors appear to be generally about 1 kt or less over the entire 40 to 120 kt IAS test range, and that is excellent. They show that the WASP is actually flying about one half to 1 kt faster than indicated.
While the aft fuselage side static pressure orifices provide an almost perfect static pressure source, they are subject to clogging when flying through rain or when dumping water ballast. For that reason a pneumatic switch of some kind should be installed, teed into the sailplane’s static pressure line, such that the pilot can switch to an alternate static source if and when clogging occurs within the basic static pressure line. Venting the alternate static pressure source to the cockpit usually provides a fairly good static reference pressure, and I have used that many times in the past.
SINK RATE TEST FLIGHTS
For these tests we had to wait until the atmosphere became relatively calm with little vertical air motion or horizontal wind shear at the flight test altitudes. It had been a windy and cloudy fall season in Texas, but finally on the 14th and 15th of December the atmosphere became acceptably calm for sink rate testing. Three high tow test flights were performed with the sailplane in its factory delivered condition. The sink rate test and L/D data from these 3 flights are shown plotted in Figures 4 and 5. A minimum sink rate of about 114 ft/min at 40 kts, and a best L/D of a little over 40:1 at a remarkable 61 kts are indicated. Subsequent thermal soaring tests showed that the C304 Wasp climbed well in weak thermals.
The above sink rate measurement tests were performed with small factory supplied wing tip wheels installed at the wing tip trailing edges. The wing tip wheels were encased within well-streamlined molded fairings that allowed only the bottom most portions of the small 60 mm diameter wheels to be exposed to the airstream. They added a small amount of drag to the sailplane, but likely not very much. The factory tip wheel installation is well done and should not have much effect.
However, we did not test with the wheels removed. The Wasp needs some sort of skid if the tip wheels were removed. If one is concerned about the tip wheel aerodynamic drag, I suggest that they try comparison flying with others and see if they can notice any difference. The Wasp’s wing airfoil appears optimized for low and mid airspeed operation - which is excellent for an all-around good flying sailplane.
WING OIL FLOW TESTS
The factory had installed full span .5 mm high Zig-Zag turbulator tapes on the wing bottom surfaces at the .70 chord location. Wing oil flow test flights were conducted at both 50 and 70 kts. The resulting oil flow patterns appeared normal at both of those airspeeds, with extensive low drag laminar flows indicated on both the top and bottom surfaces. No significant airflow separation bubbles on the wing were indicated by the oil patterns at either airspeed.
PERFORMANCE COMPARISON
For polar comparisons, the Discus 2B and the LS-8a were used because they are currently at the top of the current Standard Class contest score sheets worldwide. We had tested Sam Fly’s Discus 2B N4SF four years ago (Ref. B), and Dick Mockler’s LS-8a N90IT five years ago (Ref. C); therefore we had comparable test data for those sailplanes. As shown in Reference B, the Discus 2B achieved a little above 40:1 L/Dmax at about 56 kts unballasted. The Reference C flight test data shows the LS-8’s measured L/Dmax was almost 40:1 at about 52 kts. The Discus 2 flight test wing loading of 7.26 psf was almost identical to that of our 304C’s 7.23 psf wing loading. Since our LS-8 flight test wing loading was a bit lower at 6.51 psf (the LS-8 has about 7 sq-ft more wing area), I corrected its polar by the theoretical square-root-of-the-wing loading method to match the 304’s 7.23 psf flight test wing loading.
Those polar data are shown plotted, along with our new 304C WASP test data, in Figures 6 and 7. Note that although lacking somewhat in comparative high-speed glide performance, the Wasp polar shows very good relative performance in the low-to-mid airspeed range. Very important to strong day contest racing is the cruise performance above about 70 kts. At 87 kts the unballasted Wasp appears to have about 6 kts less airspeed when flying at the same 400 ft/min sink rate as the LS-8a, and about 10 kts less airspeed than the Discus 2’ polar. So high-speed racing is not the 304C’s strong point, but weak weather could easily even the contest scoring.
The modern day racing and cross country sailplane designers appear to be emphasizing superior cruising performance and not worrying too much about L/Dmax values. Our recent tests of the contest winning Standard Class LS-8 and Discus 2 sailplanes indicated just that. Their L/Dmax values measure close to 40:1, but really good L/Ds are shown above 70 kts, even when tested in their unballasted condition.
WING SURFACE WAVINESS MEASUREMENTS
We made chordwise waviness measurements of our test 304C’s wing top and bottom surfaces at 7 spanwise stations along each wing, using a standard 2-inch long wave gage. The magnitudes of the 304C’s wing surface waves were surprisingly small, averaging a little less than .003 inches peak-to-peak, and that is very good. Only on the wing top surfaces just ahead of the airbrakes, and again near the wing tips did our measurements exceed that value. Those waviness measurements are for peak-to-peak magnitudes –from valleys to peaks. Those data are shown plotted in Figure 8.
GENERAL CHARACTERISTICS
Commendably, all of the Wasp’s controls connect automatically upon assembly. The cockpit is enclosed by an excellent forward hinged canopy system, and the plexiglass canopy itself has very good optics. The cockpit is well sized and very comfortable, with rudder pedals and seatback being adjustable in-flight.
The cockpit sideward visibility is very good, and the forward visibility is much better than with some of the new Standard Class sailplanes that I have test flown recently. That appears to be due to the Wasp’s wing incidence being set at a higher angle than those of the Discus 2 and LS-8. I always appreciate being able to see the tow line when flying an aero tow because that adds to flight safety.
The Wasp is easy to fly, handles well, and the cockpit is comfortable and well configured. Its stall characteristics are surprisingly gentle, with almost no tendency for the sailplane to drop a wing during my low airspeed maneuvering tests. My 45-to-45 degree roll rate measurement tests showed about 5.6 seconds at 45 kts, and 4.2 seconds at 50 kts. The wing airfoil is reported to be a modified HQ 014-1642, and it appears to perform well. Apparently that is where the Wasp gets its excellent stall characteristics and extensive low drag laminar flows.
The wing root spar arrangement is of the excellent fork-and-tongue arrangement that I think is superior to the commonly used overlapping single spar roots.
The left wing spar root is the forked one, and for that reason it is inserted first during assembly, because it completely fills the square fuselage-mounting slot. The single tongued right wing spar root is then easily inserted into the left wing’s forked spar. The forked spar rooted left wing panel is a bit heavier, and it weighed about 156 lbs. The right wing panel weighed about 151 lbs.
The Wasp’s double plated wing top surface only airbrakes are very adequate. However, care must be taken to not open them abruptly at high airspeeds. As with most sailplanes equipped with powerful top surface only airbrakes, their rapid extension above about 70 kts causes a strong reduction in wing lift, sometimes sufficient to put the pilot’s head through the canopy if he is not tightly strapped in. Sailplanes equipped with both wing top and bottom surface airbrakes are much more benign in that respect, in that they do not appear to exhibit any significant delta “G” effects when the airbrakes are extended suddenly at high airspeeds.
Water ballast tanks are installed in each wing leading edge, capable of holding a total of about 115 liters, or about 254 pounds. No tail fin ballast tank is included, but instead a cavity is provided at the base of the rudder where an easily removable lead ballast weight can be installed when needed. Since Dean and I were both flying the Wasp without water ballast and near its 167 lb minimum allowable cockpit weight, we certainly did not need to add any tail ballast weights. On the other hand, this sailplane was neatly equipped with an easily accessible ballast-mounting cavity ahead of the rudder pedals, and the factory provided five 1.5 kg lead weights that can be mounted there when needed.
The early winter thermals during our Caddo Mills flight-testing were weak during my 2-day portion of the flight tests; so I was able to soar it for only less than about one hour. During that limited weak thermal testing, I thought that it thermalled well. Dean Carswell performed the sailplane’s flying qualities testing a few days later, and he was able to better evaluate the C’s thermalling flight characteristics. He will present his evaluations separately.
The current price of the new 304C Wasp is EU 35,525, plus trailer and shipping. A number of basic instruments and auxiliary items are included in the sailplane’s basic price. The optional winglets add EU 1,255 to the basic price.
For more options go to: http://www.wingsandwheels.com/304C%20options.htm
SUMMARY
The new 304C sailplane is, in my opinion, an excellent sailplane for many pilots. It appears to be of high quality in design, construction, and finish. Its powerful Schempp-Hirth type airbrakes are easy to operate and provide very good landing approach control. A favorable exchange rate with the Czech Republic makes its purchase here attractive.
Many thanks go to Andre deBaghy for allowing his fine new sailplane to be used for our flight tests and to the Dallas Gliding Association for providing both the hangarage and the high aero tows needed to accomplish it. Also to Southwest Soaring’s manager Mike Salano, and his Caddo Mills tow pilots who did the excellent towing. They usually required only about 22 minutes to tow me to 12,000 ft AGL with their powerful Pawnee.
REFERENCES
A. Johnson, R.H., A Flight Test Evaluation Of The 304CZ Sailplane; Soaring- July 2000
B. Johnson, R.H., A Flight Test Evaluation Of The Discus 2B Standard Class Racing Sailplane; Soaring- May 1999
C. Johnson, R.H., A Flight Test Evaluation Of The LS-8a Standard Class Sailplane; Soaring- July
Flying the HpH Glasflügel 304C Wasp
Dean Carswell
Dick Johnson invited me, in conjunction with his Flight Test Evaluation, to give my impression of the operational and handling qualities of the standard class HpH 304C. This is a development of the HpH 15 meter racing class (flapped) Glasflügel 304CZ which I tested some 3 years ago (Reference 1). As befitting its Glasflügel heritage, the new model now bears the name “Wasp”. The 304C (as does the 304CZ) conforms to JAR 22 design standards and has an FAA approved type certificate in the utility category.
As state-of-the-art standard class ships become increasingly costly, there is a growing group of more moderately priced new-build gliders becoming available. The Schempp-Hirth Discus CS and Rolladen-Schneider LS 4 are examples of older designs still in current production with marginally less performance. The 304C Wasp fits within this group, with a cost of around two-thirds that of the current crop of standard class national contest winners.
The ship is of generally conventional layout, with mainwheel located ahead of the center of gravity. The wings are mid-mounted with swept-back vertically oriented winglets at the tips, and tailplane is of T form with a fixed horizontal and separate elevator. The latter is controlled by a parallelogram configured control column designed to eliminate pilot induced oscillations. Elevator trim is accomplished by a stick mounted trim system, of which more later.
The cockpit is comfortable and roomy and appears almost identical to the flapped CZ. The latter just failed to comfortably accommodate a token 'large' (6 ft 5 in/196 cm) pilot, who described the fit as larger than a Discus or Ventus, but smaller than an SZD 59. Seatback and headrest are both adjustable. The Wasp is fitted with the landing gear retraction lever positioned on the right side of the cockpit, and airbrake control on the left side. The seat pan is deep, a good safety feature, which avoids the need for a 5-point seat harness and prevents "submarining" in the event of a sudden deceleration. This arrangement was reasonably comfortable and gives good support to the thighs, likely reducing fatigue on very long flights. A high density foam cushion on the seat pan would add to the comfort and provide more protection in the event of an arrival with a high vertical rate of descent.
The canopy is hinged at its front end with a locking pin at the rear center. Emergency jettison is effected by two levers situated well forward on the canopy frame which, when operated, allow the front end of the canopy to be released and pushed up into the airflow. This enables it to rotate around the Rüger-type hook fitted at the rear, and clear of the cockpit. In a real emergency, I would be happier if the levers were closer to my normal reach
Empty weight of the test ship was 597 lb/271 kg, with a max. gross of 827 lb/375 kg dry and 992 lb/450 kg with full water ballast. A wing area of 107 ft²/9.90 m² gives a maximum wing loading of 9.3 lb/ft²/45.45 kg/m². Maximum permitted water ballast is 30.4 US gal/115 liters, or about 254 lb/115 kg. Minimum cockpit weight was 167 lb/76 kg with the normal JAR 22 maximum placarded at 242 lb/110 kg. The extreme nose of the cockpit has provision for 4 lead ballast plates each weighing 3.3 lb/1.5 kg.
I fitted my 5 ft 9 in/175 cm frame in a seating position as high as possible while still getting adequate clearance (1½"/3.8 cm) between my hat and the canopy. At rest with tail down, and again on tow, this gives a good view forward. This is assisted by the molded cowl over the panel ingeniously incorporating a groove along its length to give a clear view of the magnetic compass, set well forward in the groove and well clear of the metal mass attraction of the other instruments in the panel.
Unlike many standard class ships, the Wasp flight manual made no recommendation to keep the airbrakes open to improve lateral control at the start of the takeoff roll. Despite a crosswind of 5 – 10 kt/9 - 19 km.hr blowing at 45° – 90° to the runway heading, I encountered no lateral control problems, and the tailwheel kept the ship straight with no effort on my part.
Immediately apparent as I took off for the first time was the contrast between pitch and roll sensitivity. The elevator, controlled by the traditional Glasflügel parallelogram type stick, is delightfully light and high geared, though not oversensitive. The ailerons, on the other hand, felt rather low geared in comparison. This may take a little bit of time to become accustomed to, requiring small gentle movements fore-and-aft while making large rather deliberate movements from side to side. While on the subject of controls, the Glasgflügel stick-mounted spring trim system, actuated by pressing the little finger on a button located near the base of the handgrip, is a pleasure to use, and effective throughout the practical speed range. It also can be set by moving a small knob mounted on a semi-circular wheel fixed on the horizontal part of the parallelogram control column just ahead of the pilot's fingers. Trim position can be checked from the position of the knob. While failure to set the trim correctly before takeoff is clearly an important oversight, the lightness of the Wasp’s elevator and the consequent small amount of trim force required to eliminate such loads means that such an oversight could be quickly and easily overcome.
On tow, the ship is easy to control. Bringing up the landing gear after tow release is simple, and can easily be accomplished with one hand. Once off tow, good handling qualities are at once apparent. Visibility was good, both over the nose, even when turning, and elsewhere. Leaning forward slightly, I could see the tip of the horizontal tailplane. Coordination was easy, but it was possible to run out of rudder using large aileron deflections at low speed.
The cockpit ventilation is good, both from the well placed Mecaplex® vent on the canopy side, and from the nose vent controlled by a push/pull knob at the bottom of the instrument panel. This delivers air through two adjustable "butterfly" louvres located in the left and right corners of the panel. With all of these closed, cockpit sealing of the test aircraft was shown to be good with very little extraneous noise. There is a little hole in the top of the fuselage just behind the canopy connecting to a T behind the pilot’s head. This is a vent used while filling the water ballast tanks, which removes the need for vents in the wings. In the test ship, nothing was attached to the T; and on my second flight, a small piece of tape over the hole appeared to reduce materially what noise there was.
My weight of 160 lb/73 kg with parachute plus 2 ballast plates put me close to the rear c.g. position. That notwithstanding, it was difficult to induce a stall, which occurs only with high nose attitude and after a moderate amount of airframe vibration. The ailerons remained effective right down to (and indeed beyond) the stall, and recovery was quick although, particularly from a turning stall, speed built up rapidly in the ensuing dive. Attempts at spinning were essentially unsuccessful with all my attempts ending up in spiral dives. This was all without water ballast.
My flights were carried out on a mild early winter day with a high of around 59°F/15°C and light westerly winds giving weak lift up to 3,000 ft/915 m AGL. The clean, straight ahead stall had occurred in the low thirties (knots), although I couldn’t accurately establish the precise value as disturbed airflow from the wing struck the tail mounted pitot head just before the stall occurred. Based on this and a yellow triangle speed of 46 kt/85 km.hr, but without the benefit of the quantitative test results, I attempted to circle at 40 – 42 kt/74 – 78 km.hr at 30° – 40° bank. This resulted in some roll instability and difficulty maintaining pitch attitude. Not a good thing when trying to stay centered in scratchy lift! Concluding that this was likely caused by wing laminar flow separation, I tried a little faster and found that thermalling at 44 – 45 kt/81 – 83 km.hr was easy, straightforward and felt comfortable, and the ship seemed to climb well. I was able, more or less, to stay up level with a Ventus A with which I shared a couple of thermals.
The double-segmented top surface Schempp-Hirth type airbrakes have a large breakout force, at least at the ambient temperature on the day my test was made. The manual quotes a glide ratio of 1:5 with the brakes fully open. Opening these with stick held produces only a moderate lowering of the nose. Despite their effectiveness, only a small pitch down compensation is needed to maintain airspeed upon opening the brakes with nose attitude held constant. Slipping, should it ever be needed, is easy.
The drum-type wheel brake is reasonably effective (a hydraulic disc model is an option), and operated by the heels moving the rudder pedals forward together. This may require bringing the rudder pedals closer as part of the pre-landing check. Approach and landing are straightforward with little float using half the powerful airbrakes, leading to a two-point touchdown. A fully held off landing with full brake would likely have the tailwheel arriving before the mainwheel. Despite the crosswind, directional control was easily maintained until the wings could no longer be held level at the very end of the rollout. Small wingtip wheels make the process simpler by reducing ground drag at the tip and the tendency to swing.
Despite my comment on elevator/aileron harmonization, the overall feel is of a pleasant high performance sailplane. Control forces increase moderately as speed is increased, but remain relatively light throughout most of the speed range – up beyond the rough air/maneuvering airspeed of 108 kt/200 km.hr up towards the redline speed of 135 kt/250 km.hr. Mild aerobatics (inside loop, stall turn/hammerhead, and lazy eight) are permitted. While unlikely to satisfy the desires of an aerobatic enthusiast, the maneuvers are easy to accomplish and provide a pleasant way of burning off height at the end of a Sunday afternoon's soaring. That said, however, no aerobatics should be of the self-taught variety.
The Wasp is a pleasant, comfortable and straightforward aircraft to fly, with no obvious vices or serious shortcomings. Accepting the complication of retractable landing gear, which can be made less significant by thorough briefing, proper use of a checklist and a suitable gear warning device, operation by relatively inexperienced sailplane pilots should present few problems. As always, a careful and systematic approach to conversion (Reference 2) will pay dividends and avoid surprises.
The HpH distributor for North America is Tim Mara of Wings & Wheels (www.wingsandwheels
.com) - further details of the Wasp can be found on the webpage. Price is set in Euros, presently €35,525, FOB Kutna Hora, Czech Republic, equivalent to US$36,850 and C$57,100 as of the end of December 2002.
My thanks to Andre deBaghy for allowing me to evaluate his new sailplane, to Dick Johnson and Jeff Baird for their help and advice, and to Dallas Gliding Association for contributing the tows.
References:
1. Richard H. Johnson and Dean Carswell: A Flight Test Evaluation of the Glasflügel 304CZ, Soaring, July 2000, page 30.
2. Dean Carswell: Sailplane Type Conversions, Soaring, September 1996, page 18.
About the Author:
Dean Carswell holds a Gold badge with 2 Diamonds, has been an active gliding instructor for over 35 years, and is presently the SSA’s Chief Master Instructor. The Wasp is the 132nd model of sailplane he has flown.
