Note that the Nemesis empty mass fraction is much higher than the other two general aviation aircraft. The method seems to overestimate the mass of the landing gear. This may be due to the design of the landing gear (small and with perhaps no brakes) for racing aircraft. The above analysis does give a reasonable estimate for the combined (wing + fuselage) structure ratio. Because of the difficulty of accounting for the wing to fuselage joint structure into either the fuselage or wing mass component, uncertainty always exists to the precise division between wing and fuselage components. Method 3 appears to underestimate the wing structure and overestimates the fuselage of the Nemesis aircraft. Applying factors of 0.85 for the wing, 0.83 for the control surfaces, 0.90 for the fuselage and 0.95 to the landing gear result in the estimations (per cent MTOM) for three specimen aircraft shown in Table 6.5. Although research shows that composite structures can reduce mass by 20 to 30 per cent, it has been found that such improvements are only achievable in large aircraft structures due to the connections required to feed loads into and out of the shell. Method 3 allows the incorporation of ‘technology factors’ that accounted for composites. A word of caution is appropriate here as the Nemesis is mainly built from composites and the formulae used are based on conventional metal structures. The structural results seem to be more variable. 6, 7 All the methods give reasonable results that generally bracket the actual values. Method 1 is a well-publicised general aviation method, 4 method 2 is a method used for civil aircraft design 5 and method 3 is mainly associated with military aircraft. Detailed analysis will be needed to determine the absolute effects of the layout differences. Aerodynamically the high aspect ratio of the canard will provide a lower induced drag but the sweepback will reduce lift capability. This will make the wing structure lighter giving a lower aircraft empty mass. The ‘conventional’ will have a low aspect ratio (5.5) to reduce aircraft span and roll inertia. The shape of the canopy will be significantly different on the two aircraft due to the mid-fuselage position on the conventional and the forward position on the canard layouts.Īlthough structurally heavier, the ‘canard’ wing will have a higher aspect ratio (7.5) to provide for a greater fin arm. Cockpit size will be kept as small as practical within the formula rules. A constraint analysis could be conducted later in the design process to show the influence of these restrictions on the design. m) and the engine power at 75 kW to the propeller is set to match the fuel cell performance. The wing area is set at the minimum allowed by the rules (66 sq. Unlike most aircraft projects, the selection of wing area and engine power is not a problem as they are part of the Formula rules. Marchman III, in Aircraft Design Projects, 2003 6.6 Initial sizing There is a higher incidence of herniated intervertebral disks postflight than that seen in the general population ( Johnston et al., 1998 Hargens et al., 2016 Taggart et al., 2016). (2010) also found that motor control adaptation in the first few hours of re-entry into 1 G to walking an obstacle course predicts long-term recovery.Ībout 75% of Space Shuttle crewmembers experienced back pain upon returning to Earth. (2010) found that crewmembers returning from an average of 185 days on ISS exhibited a 48% increase in the amount of time required to traverse an obstacle course and that recovery to preflight time required to traverse the course took around 15 days. Muscle strength typically returns to normal within 4–8 weeks, but depends on many variables. Although there is no increased incidence of fractures due to bone loss postflight, for flights greater than 6 months this may not be the case ( Barratt and Pool, 2008). On average, crewmembers that spend 6 months on the ISS lose 11% of the bone mass in their hips. Crewmembers that do not fully recover still returned to within 5% of their preflight bone levels. Beard, in Space Safety and Human Performance, 2018 5.4.3 Musculoskeletal Systemįor most long-duration flight astronauts, full bone recovery is typically achieved between 6 months and 3 years of returning to Earth but may never recover to the original strength for the same amount of mass ( Sibonga et al., 2007).
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