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rbjjr
Joined: 18 Mar 2007
Posts: 36
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 Posted: Sat Sep 06, 2008 10:04 am Post subject: Aviation Quebec Magazine CH 750 Article |
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Looks like there is a potentially good article on the CH750 in Aviation Quebec magazine and linked to the Zenith site. However, it's in French. Anyone know if there is an English version or translation?
Rgds,
Burke Johnson
CH701
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flicka750
Joined: 02 Aug 2008
Posts: 31
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| Posted: Sat Sep 06, 2008 11:41 am Post subject: Re: Aviation Quebec Magazine CH 750 Article |
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| rbjjr wrote: | Looks like there is a potentially good article on the CH750 in Aviation Quebec magazine and linked to the Zenith site. However, it's in French. Anyone know if there is an English version or translation?
Rgds,
Burke Johnson
CH701 |
Complete report
Just like its predecessors, the CH750 is a plane with the design voluntarily with share. A kind of jeep of the sky to the arrises and apparent hardware. One likes or one hates, but the style does not leave indifferent. Personally, I like best the machines with the purified lines, but force is to recognize that the concept likes and is salesman. Proof in is, the troop of original CH701 flying in the world, plus the few thousands of counterfeits and disseminated substitutes that and there. In any event, classified airplanes STOL are never very beautiful. Fieseler Storch model which engineer Chris Heintz took as a starting point to create his CH701 or the PZL Wilga and other Courier Photogravure never radiated not by their smoothness!
Profile STOL: explanation and application
English acronym STOL is resulting from the word group Short Takeoff and Landing. In French, that gave s.t.o.l, that is to say short take-off and landing aircraft. The aerofoils of this type have a marked camber and are equipped with fixed nozzles of leading edge or not. These small auxiliary airfoils prevent unhookings until an angle of attack of approximately 30 degrees. The slit, located between the wing and the nozzle, forms a system of venturi which forces the air to accelerate with the passage and tangentially channels it on the suction face. When the plane is very pulled up, the turbulent nets are then levelled above the aerofoil: that delays collapses it. On CH 701, CH 801 and now CH750, these nozzles have the characteristic to be fixed, and this, for practical and economic reasons. Indeed, to assemble retractable profiles would not lower the stalling speed of hardly some N uds but would complicate the fitting passably (addition of complex parts, profit of weight, additional maintenance). The wing tips selected are, as on the preceding models, of Hoerner type: ends bevelled with 45 degrees. Simple to build and effective, they make it possible to maximize the effective scale (in opposition to the geometrical scale). Thanks to them, the marginal swirls are mainly reduced. Lastly, will flaperons them mobile surfaces full width acting as ailerons and of shutters maximize the coefficient of bearing pressure and support a fast rate of roll. They are voluntarily downwards eccentric compared to the wing (assembly offset). Those thus do not undergo the lay effects limiting, because the air passing between them and the trailing edges of the two half-wings protect them from the negative repercussions.
Special horizontal stabilizer
With the great angles, the tail of a plane STOL must be naturally “drawn” downwards. With reduced swiftness, that supports quasi instantaneous rotations and the round-offs followed by ultra-short makings of contact. On the CH750, the design is studied in this direction. The profile of the horizontal stabilizer is voluntarily reversed, which creates a negative bearing pressure. Moreover, that generates an effect of venturi which acts on the airfoils by delaying the splitting of the airflow at the time of the deflection of the elevator. Contrary to the majority of the aircraft, the empennage of this new model is higher than the normal. Moreover, the half-wings do not meet above the cockpit. The slipstream is thus moindrement disturbed when it meets the fixed plans and mobiles.
Construction all-metal
Following the example its predecessors, the future CH750 will be built out of alloy aviation and steel chromium-molybdenum. The assembly will be mainly carried out using rivets known as blind. Manufactured by Textron Avex, those resemble ordinary pop rivets but are approved aviation. The customers who will buy the apparatus in kit will be able to assemble it by stage, that is to say a module at the same time. As an indication, the cell will break up into as many definite sections being able to be gone up independently from/to each other. The aerofoil, for example, will be divided into 6 segments, that is to say 2 wings, 2 will flaperons and 2 nozzles of leading edge. While going from simplest (will flaperons them) towards most complicated (wings), the manufacturer beginning will be able to acquire experiment with few expenses. The fuselage, as for him, will include/understand 2 distinct parts: a structure postpones made up of 4 regular polygonal panels joined together on executives in aluminium angle + a cage out of weld steel tubes defining the cabin. The whole will be homogeneous and light at the same time. Moreover, the load factors are encouraging since the airframe manufacturer announces from the start: +4 G/-3g.
Robust landing gear
At the technological level, the undercarriages of the CH750 will not differ from those from the CH601, 640,701,801 and 2000. The formula having proven reliable in terms of robustness and economy, useless to reinvent the wheel! The principal train will thus remain a formed Cantilever of a solid curved blade. Only dimensions will change. Thus, the CH750 will gain 10 centimetres (± 4 Po) in height compared to the CH701. As the fuselage will be itself broader (0,97 m against 0,85 m or 3 pi 2 Po against 2 pi 9 Po), this increase proves to be logical. The rims, out of alloy, will receive large tires Carlisle 8.00 X 6. Matco will provide the disc brakes. The nose gear leg will remain tubular and controlled to the swing bar. A folded elastic cord will act as shock absorber. Functional Hyper and practically without required maintenance, one will reproach only the device his unflexibility compared to an oil and air system.
Recommended Continental engine
Just like very awaited Cessna 162 SkyCatcher, sportsman AMD Zodiac CH601 or traditional American Champion 7EC, Zenith CH750 version LSA will fly with an engine Continental O-200. Coupled to two-bladed Sensenich with adjustable step (manually with the stop), this opposite four-cylinder engine develops a substantial power (100 ch with 2750 rpm). Ancient design, this one enjoys a indéfectible popularity near the pilots and the mechanics, because its maintenance does not pose problems, its potential (TBO) is rather high (1800 hours) and its reliability reassures. However, even if we are numerous to protest that it is “a true” engine of plane, force is to recognize that it weighs 29 lb (13 kg) moreover than one Rotax 912S and than it is a little greedier oils some and carburizing. Obviously, the manufacturers amateurs will be able to adapt a motorization of their choice on the CH750 bought in kit. With almost equal weight, one will then see certainly six-cylinder cars Jabiru 3300 (107 ch) humming of power in margin of impossible to circumvent Rotax 912 and 914.
Flexible versions
Sebastien Heintz, wire of Chris Heintz and president de Zenith Aircraft, project to put the model in market as of October 2008. Initially, the CH750 will be available exclusively in regular kit. An option with fast assembly (quick built kit) will follow in the tread. Later, a version, classified turn-key LSA, will be born. This series could be assembled at AMD, in Georgia, or quite simply at Zenair, in Ontario. In Canada, in the absence of regulation (standard LSA expresses does not exist) and in waiting of a hypothetical equivalence, the customers will have to register their apparatus in construction amateur.
Standardized production
My preceding visit at Aircraft Zenith goes back already to several years. It was at the time of the test of Zodiac CH640 four-seater of voyage, derived from the two-seater certified CH2000 Alarus. On the spot, at the aerodrome of Mexico City (Missouri), I find my friends Roger Dubbert, the test pilot sympathetic nerve of the company, and Sebastien Heintz, always so serious and facetious at the same time! New heads also made their appearance, like Caleb Gebhardt, a young aeronautical engineer specialized in structural calculations. This one was engaged to assist main Heintz. Benefitting from a well deserved semi-retirement, this last division from now on its time between its property in France and its businesses in North America. With the production, a score of skilled workers work in the principal hangar. I recognize some faces and exchanges cordial greetings. Since the last time, the equipment was modernized. A cutting machine CNC (with numerical control) of mark C.R. ONSRUD now makes it possible to produce component count small or large with the chain. Cutting up, drilling or fitting are thus standardized. All that at the speed of the flash
or almost! Together, two employees supply the untiring robot. Further, subsets are assembled. Elsewhere, others control quality or enter parts. Each day, several kits all models confused are thus made up, packed and sent. The functions seem well defined. Work sufficiently appears easy because ground. People post this happy air which those have whose work is carefully made.
Discovered prototype
The production of CH750 STOL began this spring. At the time of my passage, at the end of May, the fuselage with half is already built. The equipment of the wings will not delay. The engine, its frame manufactured at Zenith and wiring await their imminent installation. There will remain the cap in composites to be moulded and the color of painting to be chosen (doubtless yellow). The final assembly will take place right before the official launch envisaged with Oshkosh, at the end of July. The reaction of the public should be positive, because the model corresponds to the current trend. Enthusiasm emanating from many unconditional as from the new followers will surely mark this go. Opposite the editing tables, reserved for number 001, broad industrial doors open on the tarmac. Outside, the sun darts its rays on the prototype registered N750ZZ. The metal, left with naked, is extreme. The apparatus is rough and the quasi non-existent completion. Nothing abnormal since it is a machine of factory! Tens of wool bits scotchés on the cell testify to the tests carried out and those to come. Only some sections were painted out of orange fluo for the express needs for our report-photographs. First of all, the CH750 seems hardly larger than its elder CH701. However, put aside the back empennage, all were redimensionné. One cannot truly quantify the percentage, because increases all are not proportional. Nevertheless, at sight of nose, I would say that the profit turns between 10 and 15 percent. In fact, in addition to the size of the machine, it is mainly the cabin which was reconsidered and improved. More roomy and more glazed definitively, it invites to the piloting of proximity and the location.
While going up on board, I notice that the access is easier than on the CH701, because the embrasures of the doors right-hand side and left (removable) are more indented. The central handle typical with brand name Zenith releases from space for the legs. The windshield goes down very low forwards and on the sides: that maximizes the external sight. I appreciate the concept. Behind the seats, of each edge, a broad trapezoidal port-hole lights the compartment with luggage. Very well! The seats, on the proto, are functional without more. The direction ensures that they will be more comfortable on the planes and the kits of series. The instrument panel, in half-moon, can accomodate an analogical or numerical instrumentation. In fact, it is a screen multifunction Dynon Avionics which equips the specimen. This Primary Flight miniature Display deserves, without question, the qualifier of little marvel! Programmed to treat a crowd of information simultaneously, it posts attitudes and given without delay. Throttle linkages, richness and of reheating carbu, emergent without grace of the lower part of the table. Electric switches, circuit breakers and another indicators strew part of remaining space. After all, the look corresponds to the image given of a plane of bush! A voluntary orientation, confirmed by this dear Sebastien.
The test plug of the prototype, of exclusiveness
After a catch in hand carried out under the supervision of Roger Dubbert, I leave in solo for a series exercises and tests. I appreciate the confidence which the company Aircraft Zenith testifies to me by entrusting the single specimen to me to this new CH750, and I measure the consequences in the event of damages of them. However, I am there to evaluate the apparatus and not to push it out of his limits. Forty minutes after having redécollé in solo, I must stop the flight, because the conditions weather are degraded suddenly. Gusts of wind exceeding 30 kt (56 km/h), frays with downpours, announce a violent one storm. Return on the ground. Tomorrow, the sky will be more lenient! Towards 7:30 of the morning, I take again indeed the handle in hand. The sky is of azure. Perfect! This time, I will be able to work conscientiously but also to benefit fully from the machine. The air custom is almost null at this beginning of day. After a takeoff runs on the 24, I go up in the axis to 2000 foot-ground (610 m). Well quickly, I fly over too quiet Mexico City then I transfer on the left to move away me towards the south. With approximately 10 nautical miles (19 km) of the installations, N750ZZ is stable, on the level, to 3500 foot-sea (1067 m). Speeds, the driving mode, the rate of rise and several other parameters were already noted during the rise. The tests can continue. Here the sheet of the integral statements and comments associated. Note: all recorded speeds are in mph, because the anemometer and the portable GPS are thus gauged on the prototype.
Date from the test: May 31, 2008
Place: Mexico City, Missouri
Code airport: MYJ
Geographical coordinates: N39 09 45 W91 49 10 Altitude: 823 pi (251 m)
Pressure: 29,95 Hg
Temperature: 22° C
Wind: 250/6
Ceiling: CAVOK
Track: 24
Length: 5500 pi (1676 m)
Coating: asphalts
Obstacles: not
Registration of prototype CH750 STOL: N750ZZ Hours of flight: 68
Empty weight: 775 lb (352 kg)
Fuel load: 24 Gall (91 L), is 144 lb (65 kg)
Pilot: Richard Saint-George Weight: 180 lb (82 kg) Weight cargo liner: 5 lb (2 kg)
Mass day: 1104 lb (501 kg)
Maximum mass: 1320 lb (599 kg)
Centering: OK. In the envelope
Taxiage: normal. Good precision.
Steering: normal. The swing bar is flexible and efficient.
Braking: passable, even insufficient. The clamps unit, plates and Eringer discs will be replaced by of Matco on the models of series.
P.A. on takeoff: 28 Po Hg
RPM on takeoff: 2480 rpm
Flaperons: 7 degrees. That corresponds to half of their race. It is what the airframe manufacturer recommends to carry out a short takeoff. In comparison, that is equivalent to a steering of approximately 15° on regular shutters.
Time of rolling: 5 dryness. The angle of attack is estimated at 20 degrees.
Number of revolutions (Vr): 35 mph (30 kias 56 km/h) Without anticipation, this one is carried out normally with 45 mph indicated, that is to say 39 kias (72 km/h).
Speed in rise (Vy): 67 mph (58 kias 108 km/h)
Rate of rise (Vz): 800 pi/mn (4,06 m/sec) Taking into account the altitude-density, is 1794 pi (547 m), the result is encouraging (brought back to the data of the manufacturer, in conditions standards).
Altitude of work: 3500 pi (1067 m)
Temperature: not raised. No thermometer is assembled outside.
Estimated ceiling: unlimited
Conditions: VFR. A light wind of north blows uninterrupted.
P.A. in cruising: 23 Po Hg
RPM in cruising: 2420 rpm
Cruising speed recommended: 85 mph (74 kias 137 km/h) the following statements show the precision of the anemometer integrated into the PFD. The average speeds-GPS being of 89,5 mph (78 kt 144 km/h), there are only 2 N uds difference with the values indicated.
Cape: 180 (south)
Speed indicated: 92 mph (80 kias 148 km/h)
Speed GPS: 97 mph (84 kt 156 km/h)
Cape: 360 (north)
Speed indicated: 92 mph (80 kias 148 km/h)
Speed GPS: 82 mph (71 kt 132 km/h)
Maximum speed (Vne): 125 mph (109 kias 201 km/h)
Speed of man uvre (Goes): 78 mph (68 kias 126 km/h)
Speed in slow flight: 58 mph (50 kias 93 km/h) Shutters: 1/2 Elevating: 7 degrees
Stalling speed out of stringer (Vs): 45 mph (39 kias 72 km/h).
Stalling speed full will flaperons (Vso): 42 mph (36 kias 68 km/h) Light plate in piqué at the time of the exit of the high-lift devices.
Turns with great slope G + D: 45 + 60 degrees. Good stability in rolling.
Lace reverses G: <5>D: 5 to 10 degrees
Rate of roll G/D: 22,5 deg/dry
D/G: 22,5 deg/dry
Induced rolling (_ tube): > 45°. Entry in on the left more marked spiral.
Stability: positive. The apparatus returns in place after having carried out three small parabolas.
Speed planed flight: 73 mph (63 kias 117 km/h) the pitch trim is ineffective. I must maintain constantly the handle to prevent any variation speed behind.
Rate of fall: 1000 pi/mn (5,08 m/sec) Slope: 15 degrees
Speed D approach: 70 mph (61 kias 113 km/h) driving Mode: 1800 rpm
Flaperons: 15 degrees (full deflection)
Speed with the round one: 55 mph (48 kias 89 km/h)
At low speed, the elevator loses of its effectiveness. Without addition of power, the tail takes down gently. Its surface seems to be insufficient. A point of view which Roger division with me. After dialogue, the research department of Aircraft Zenith will decide to increase slightly the scale of the horizontal stabilizer. The tests being in hand, the results will make it possible to modify, consequently, the plans of the series to come.
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flicka750(AT)gmail
EINSTEIN:"Common sense is the accumulated prejudices before the age of 18" - Out of My Later Years
TWAIN: "Intercourse is life's most over-rated pleasure, defecation is life's most under-rated pleasure" - Letter's From Earth |
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