Gemballa Avionic Development
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Overview
The CM-8 is a large tactical airlifter with the capability to perform lightweight strategic airlift roles. Primary advantages of the CM-8 include a large cargo compartment with the capcity to move Main Battle Tanks and IFV's, a lightweight fuselage to allow landing on even the softest and shortest of landing strips, enhanced turboprop design promising greater efficiency at all speeds and a large fifty tonne payload.
The CM-8 is the first turboprop aircraft to be manufactured by Gemballa.
Airframe
Because the CM-8 was designed to be a large aircraft capable of performing intercontinental airlift missions, yet also operate off short, rough and sometimes non-existant airstrips, this called for a very light fuselage and mainplane of the aircraft in order to maximise it's effectiveness. To this end, designers sought to use a new generation of composite materials with what to make sure the design goals were met.
To keep the weight of the fuselage to the bare minimum, large swaths of the fuselage which were originally intended to be made with aluminium were replaced with composite materials. Composite construction is a generic term to describe any building construction involving multiple dissimilar materials, in this case carbon-fibre reinforced polymers are used. CFRPs are comprised of a polymer, in this case epoxy, which is a thermosetting polymer formed from reaction of an epoxide "resin" with polyamine "hardener", is re-inforced with fibres of carbon which give the material it's strength. CFRPs have an extremely high strength to weight ratio which makes them ideal for use on aircraft. The downside of CFRP's is that they can be extremely expensive to replace and require much more mantinence than more typical aircraft materials such as aluminium would. Thus, CFRPs have been used on the fuselage section which is above the bottom third of the fuselage and aft of the cabin. The section of the fuselage which is constructed from CFRP's is cast as two different panels which join an aluminium seam running across the top of the fuselage.
The remainder of the fuselage, the wings and the tail control surfaces are all constructed from Al-Li or Aluminium-Lithium alloy. Lithium is the least dense elemental metal, much less dense than alumiunium which is in itself less dense than most other metals, therefore when the two are alloyed together, the density and weight of the resulting material is less than that of the alloy while being stiffer at the same time and more resisitant to strain. Because the nose of the fuselage and the underside of the fuselage are the areas most sucseptible to damage, Al-Li alloy was used on these areas to offer a cheaper option of replacement than the expensive CFRP's. Because of it's stiffness, Al-Li alloy was also used on the wings which are acted upon by not only horizontal but also vertical forces unlike the fuselage and thus need to have the compressive and tensile strength required to outlast these forces, as well as resist the immensse shearing forces which are also experienced at high speeds.
Thrust
Due to the operational demands of the CM-8, designers decided to disregard the usual turbofan engine that is seen on every other large aircraft on Gemballa and instead follow a new design theorem around turboprop engines. As a result, the CM-8 is, so far, the only Gemballa aircraft to use a turboprop engine; even the smaller CM-7 uses turbofan engines.
Thrust is provided by four Azzuri TQ300 turboprop engines turning eight bladed propellers that are 5.4 metres in diameter. The power of a single engine is approximately 8,500kw and the engine itself only weighs 5,000 kilograms through lightweight materials techology. The advanced direct fuel spray system, which sprays fuel into the section of the turbine which will create the most efficient combustion, and lightweight turbine technologies which give the TQ300 a much higher power to weight ratio, allow the TQ300 to use much less fuel than the similarly powerful engine. A TOGA (Take-Off, Go-Around) power function is also fitted, giving 120% thrust for 5 minutes with 10 minute rest periods in between.
Propellers used by the CM-8 turn in a counter-rotating fasion. This counter-rotation characteristic is known as Down-Between-Engines (DBE) and the CM-8M will be the first aircraft ever to use such a configuration. The advantages of DBE have far-reaching effects both aerodynamically and structurally. Firstly, airflow over the wings is symmetrical, improving lift characteristics and the lateral stability of the aircraft. Secondly, DBE allows for an optimum wing design by eliminating most of the effects of torque and prop-wash on each wing, concentrating the airflow over the most efficient portion of the wing located between the engines. DBE also reduces the “critical engine” effect of severe yaw in the event of an outboard engine failure. The result allows a 17% reduction in the area of the vertical tail surface.
Further aerodynamic advantages inherent in DBE have been found to give a 4% increase in lift from the wing at slow speed, which enables, for the same total lift, a simpler, lighter flap system to be employed. As a consequence of the lessening of the aerodynamic forces applied to the flaps, the surface area of the horizontal tail-plane can also be reduced by 8%. Nickel-based alloy has been selected for the erosion shields of the propellers due to its durability and light weight.
The turbine itself and the compressor fan are made from a carbon-ceramic blend, which is enourmously strong and able to resist the extremely high temperatures inside the engine. Other parts of the engine are made from Aermet 100 which is a steel blend designed to cope with high temperatures and offer a high compressive and tensile strength. Exterior covering of the engine are made from Al-Li alloy, a very light weight metal.
Each engine is mounted below the wing and can be operated independently of each other. These engines do not have thrust vectoring capabilities or exhaust suppresion, as these features are not necessary for an aircraft performing these roles.
Cockpit
The flightdeck of the CM-8 was conceived as being a fully glass cockpit, without using conventional instruments. Using four large displays infront of the pilots, as well as several other LED displays around it, pilots are consistently kept up to date with what is happening to the aircraft both inside and out. On a pilot's outside screen(the screen mounted closest to the side of the cockpit), Airspeed Indicator, Altimeter, Turn co-odinator, Vertical Speed indcator and Artificial Horizon are all displayed. On the inside screen, the exact location of the plane and its waypoints and destination are displayed also, along with the planned route.
The CM-8 features a sophisticated digital fly-by-wire system. The computers "read" position and force inputs from the pilot's controls and aircraft sensors. They solve differential equations to determine the appropriate command signals that move the flight controls in order to carry out the intentions of the pilot.
The programming of the digital computers enable flight envelope protection. In this aircraft designers precisely tailor an aircraft's handling characteristics, to stay within the overall limits of what is possible given the aerodynamics and structure of the aircraft. For example, the computer in flight envelope protection mode can try to prevent the aircraft from being handled dangerously by preventing pilots from exceeding preset limits on the aircraft's flight-control envelope, such as those that prevent stalls and spins, and which limit airspeeds and g forces on the airplane. Software can also be included that stabilize the flight-control inputs in order to avoid pilot-induced oscillations.
Since the flight-control computers continuously "fly" the aircraft, pilot's workloads can be reduced to a minimum while in transit. Stalling, spinning and other undesirable performances are prevented automatically by the computers.
The CM-8 also features the Cervelo SDH-5 threat detection radar encompassing a MAWS and RWR. This alerts pilots to when a radar lock is engaged, and also allows the pilots to track enemies with a very narrow radar wave, which can be as focused as precisely to 1° by 1° in azimuth and elevation, making the system extremely accurate and can increase the chance of a succesful evasion. The SDH-5 can also communicate to other allied fighters in the area and alert them to the possible threat if the are not already, likewise the SDH-5 can receive this information. This is not featured on civillian versions of the aircraft.
Cargo compartment
Entry to the cargo bay can be done through the rear cargo bay doors
The rear cargo bay door is comprise of two components of the very rear of the fuselage. The lower component folds down to make a 10 degree angle with the ground when the CM-8 is flat while the top half of the door extends upwards to become parallel with the ground. Both ramps, front and rear, are rated to carry loads of up to eight tonnes at any one time, allowing light armoured vehicles right up to MBTs to be comfortably transported within the CM-8 Ramps are reinforced with high-tensile steel capable of resisting the immense pressures applied during loading or offloading.
The cargo bay is that of modular design and numerous different configurations can be made.
A single can be added to the fuselage to create a three level aircraft capable of carrying passengers across two decks with an undercompartment for luggage. During times when nations wish to quickly deploy personel, the CM-8 can carry over 300 troops in its capacious interior, seated on the modular deck with their full gear stowed underneath. Collapsible but crash worthy seating can be stored easily as can the decking when these are removed to allow for greater cargo capacity.
The cargo bay of the CM-8 is 18.2 metres long, 4.2 metres wide and 3.8 metres tall allowing the interior to accommodate up to two light armoured vehicles or one MBT, which the CSM was specifically designed for. In addition to this, the CM-8 can carry 120 troops or paratroopers for insertion missions, or perform a MedEvac role by carrying seventy stretchers and twelve medical personel. For humanitarian missions, the CM-8 can carry eight pallets of cargo.
Specifications
General characteristics
Crew: 5 (pilot, co-pilot, three load masters)
Length: 45.5m
Wingspan: 40.1m
Height: 14.15 m
Empty weight: 75,000kg
Max-Payload: 60,000 kg
Max takeoff weight: 150,000kg
Powerplant: 4× Azzuri TQ300, 8,500kw each
Propellers: 8 bladed, 5.4 metres in diameter
Performance
Maximum speed 824 km/h
Cruise speed 780km/h
Range 7,300 km
Service ceiling 13,000 m
Purchasing the CM-8
The CM-8 is availabe for $106,200,000 per unit
The Domestic Production Rights are not available for this model
