![]() After each flight, local residents will be asked to answer questions about how much they had noticed the re-engineered supersonic sound.Īircraft manufacturers could then use the technologies developed as part of the X-59 project to develop larger commercial planes that could carry up to 120 passengers.įollow Tereza Pultarova on Twitter Follow us on Twitter and on Facebook. After the plane takes to the sky for the first time probably at the end of next year, the space agency will run an extensive test campaign that will see X-59 fly over selected communities in the U.S. NASA hopes the X-59 could pave the way for a new era of supersonic travel that could see people zoom across continents in half the time it currently takes. ![]() "It wouldn't be startling or bothering you," he said. In a quiet rural area, they might notice what Richwine described as a "quiet thump." Of course, they can be operated at higher speeds but do so only to make up for a delay.Richwine said that most people would probably not even notice if the X-59 flew over a busy city. They fly a bit above their drag divergence Mach until the gains in speed are balanced by the losses in drag. Airliners normally fly at Mach numbers ranging between 0.78 (short range) and 0.84 (long range) and for best efficiency should stay below Mach 0.82. Mach 0.9 is only used by business jets where owners care more about bragging rights than fuel consumption. This profile is created using the mean-camber line of the Eppler-197 airfoil profile and the NASA LS-0013 symmetrical profile. But it can only serve as a starting point since wing sweep will change the pressure distribution locally and demands a shift in the point of maximum thickness (forward at the root, backward at the tip) and more negative camber at the root in combination with a higher local incidence. The computational study is conducted to evaluate the low and high subsonic speeds aerodynamic characteristics of the modified airfoil profile. This NASA report (PDF!) lists a range of supercritical airfoils with different thicknesses and design lift coefficients. Supercritical airfoils have negative camber over most of their forward part and strong positive camber only in the rearmost 20 - 30% of their chord. The added lift at the forward part also lowers the pitching moment of supercritical airfoils. On the most recent designs another small lift contribution results from a slower pressure drop on the forward edge of the lower side pressure distribution (the forward lower-surface undercutting of Phase 3 airfoils).Įffect of forward lower surface undercutting, from NASA Technical Paper 2969. Supersonic flow on the upper side allows to create more lift over the full chord. In oder to produce the most lift at a given Mach number, the pressure difference between upper and lower side can be maximized where thickness is low, i.e. Practical designs aim for a weak shock over a range of lift coefficients. Key is the low curvature on the suction side which makes a shock-free pressure rise possible. When transsonic research started, inverted airfoils paradoxically turned out to perform better at moderate lift coefficients and high Mach numbers than regular airfoils. It should be obvious which one is to prefer. While the NACA 6-digit series was among the first set of airfoils computed from a design pressure distribution, they will suffer from shocks when operated above their critical Mach number just as any other airfoil.Ĭomparison of drag rise over Mach for 6-series and early supercritical airfoils from NASA Technical Paper 2969. How do airliners tackle the problem? I think I read that they allow mach numbers a little bit higher until the drag divergence velocity? ![]() So the only way to have less sweep angle: find another airfoil (I think 64006 is already one of the best free available airfoils) or I accept higher values of drag coefficient ? for Langley Research Center NASA CR-2494. efficient to slow the oncoming flow to subsonic speeds for. So normal commerical aircraft have angles between 30 to max. subsonic or supersonic speed to a low subsonic speed b y aerodynamic. I am wondering now, if this is normal that I need such a high sweep angle? Or did I choose the wrong airfoil. In order to prevent Mach=1 on the airfoil, I would need a swept wing with an angle of more than 50° to reach Ma_crit=0.88. So actually, this is my first demand for the airfoil. So when I think of which airfoil to choose, I have to consider aspects likeīut what comes first in my mind is, that I have to prevent shock waves forming on my airfoil, because drag will dramatically increase. ![]() I am desigining an aircraft, which shall fly up to Mach=0.9 in cruise flight in an altitude of 10 km.
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