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The research projects for the essential technologies such as aerodynamics, materials and structures, propulsion systems, etc. for the next-generation supersonic transport and development program of unmanned experimental airplane have been conducted at JAXA (Japan Aerospace Exploration Agency, previously NAL; National Aerospace Laboratory) since 1997. The airplane shape is designed by CFD (Computerized Fluid Dynamics) code developed by NAL and the purpose of flight trial is to verify and demonstrate the validity of CFD design technology. This report shows the summary results of the experimental airplane design and ground test before the first trial, and also describes summary of the result of the flight trail, which was conducted on 14th July 2002 in Woomera test range of South Australia., 宇宙航空研究開発機構(JAXA)は航空宇宙技術研究所(NAL)の時代から次世代超音速機技術研究開発プロジェクトを開始し、ロケットにより打ち上げる無人の小型超音速実験機(NEXST-1;以下ロケット実験機)の開発と飛行実験を行った。実験機の空力形状はJAXAが開発したCFDコードにより設計されており、飛行実験の目的はその実証にある。基本設計は1997年度から開始し詳細設計、維持設計を経て2001年度に実験機システムが完成した。2002年7月にオーストラリアのウーメラ実験場で第1回飛行実験を実施したが、打上ロケットのオートパイロットの不具合により実験は失敗に終わった。その後、信頼性向上ための改修を行い、2005年10月10日に第2回飛行実験を成功裏に完了した。本報告書は研究開発プロジェクトの概要と第1回飛行実験にいたる設計の結果、および地上での確認試験の結果についてまとめたものであり、補足として、第1回飛行実験の状況、その原因調査、および対策検討の結果にも触れた。改修設計の結果、および第2回飛行実験のフェーズについては別途報告書がまとめられる予定である。, JAXA Research and Development Report, 宇宙航空研究開発機構研究開発報告

The latest linear theory shows that multiple instabilities co-exist in the region, where the flow becomes unstable at very low Reynolds number compared to that on the attachment line. An experimental investigation has been done focusing boundary-layer instability near the attachment line to clarify the phenomena, especially on which instability devotes to the drop of the critical Reynolds number. These experimental results are compared with the calculations done by the theory., 最近の線形理論は、付着線上の流れに比較して極低レイノルズ数時に流れが不安定になる領域では多重不安定性が共存することを示している。不安定性が臨界レイノルズ数の低下に特に作用する現象を明らかにするため、付着線近傍の境界層不安定性に焦点を当てて実験的な検討を行った。これらの実験結果を理論計算と比較した。

Flight test of a supersonic experimental airplane was performed by Japan Aerospace Exploration Agency to improve advanced aerodynamic design technologies for the next generation SST (SuperSonic Transport). The experimental airplane was designed to reduce the drag on a supersonic cruise condition. Surface pressure distributions, boundary layer transition locations and aerodynamic forces in the flight test were obtained to demonstrate the aerodynamic design concepts. The flight test results evaluated by comparing with the prediction results obtained by CFD (Computational Fluid Dynamics) based optimum design tools. The flight test results relatively corresponded to the CFD results. Aerodynamic design concepts for drag reduction were demonstrated qualitatively and quantitatively by the NEXST-1 (National EXperimental Supersonic Transport-1) flight test., JAXA Special Publication, 宇宙航空研究開発機構特別資料

In the aerodynamic design of the National EXperimental Supersonic Transport (NEXST) program, a supersonic Natural Laminar Flow (NLF) wing design concept was originally developed. Before the flight test of the NEXST-1 airplane, more detailed transition analysis should be performed in order to validate the NLF wing effect. Therefore, the NAL-ONERA cooperative research project started in April 2000, because ONERA had great ability of analyzing transition phenomena and NAL had some experimental transition data in supersonic flow. In the transition analysis on the sharp cone with a half angle of 5 degrees, the nose cone, and the NLF wing of the NEXST-1 airplane, almost good cross validation of both ONERA's and NAL's e(sup N) codes was obtained. Then, there was also high correlation between the S2MA wind tunnel test results and both laboratories' predictions under the assumption of a critical transition N value of 6. Moreover, about 40 percent chordwise region was estimated to be laminar at flight condition by NAL's code. In addition, a risk of transition due to attachment-line contamination was predicted at inner wing, using the well-known Poll's criterion., JAXA Special Publication, 宇宙航空研究開発機構特別資料

Flight test of a supersonic experimental airplane was performed by Japan Aerospace Exploration Agency to improve advanced aerodynamic design technologies for the next generation SST (SuperSonic Transport). The experimental airplane was designed to reduce the drag on a supersonic cruise condition. Surface pressure distributions, boundary layer transition locations and aerodynamic forces in the flight test were obtained to validate the aerodynamic design concepts. The flight test results were evaluated by comparing with the prediction results obtained by CFD (Computational Fluid Dynamics) based optimum design tools. The flight test results were confirmed to be corresponding to the CFD results. Therefore, the aerodynamic design concepts for drag reduction were demonstrated qualitatively and quantitatively by the NEXST-1 (National EXperimental Supersonic Transport-1) flight test., 小型超音速ロケット実験機(NEXST-1: National EXperimental Supersonic Transport-1)の第2回目の飛行実験を2005年10月に豪州ウーメラ実験場において行った。飛行実験では予定していた全てのシーケンスを正常に実施し、貴重な飛行実験データを健全に取得することができた。その中で、空力データは空力設計コンセプトを検証する上で重要な計測項目のひとつである。本稿では飛行実験で得られた空力データを評価し、空力設計の妥当性について検討した結果を報告する。具体的には、飛行実験により計測された空力データをCFD(Computational Fluid Dynamics)解析結果と比較し、抵抗低減コンセプトを取り込んだNEXST-1の空力設計に対する妥当性を検証することができた。これは機体まわりの表面静圧分布がCFD解析と概ね一致していること、胴体や主翼まわりの表面静圧分布の分析からワープ主翼、エーリアルール胴体の設計コンセプトの妥当性が確認できたこと、さらに主翼上面の圧力分布に関して自然層流翼設計に用いた目標静圧分布と良好な一致が得られたことによる。また気流乱れの小さい飛行実験条件下で、主翼上面や前胴まわりの境界層遷移データの取得に成功し、その遷移計測結果から設計点において主翼上面の境界層遷移位置がもっとも後退していることが明らかになり、自然層流翼設計の妥当性が完全に確認された。さらにその遷移計測結果を数値予測結果と定量的に比較し、境界層遷移予測ツールの精度向上に役立つ知見も得られた。特に設計点における抵抗係数の特性は、飛行実験結果とCFD解析結果で良好な一致が示され、これにより超音速巡航時の設計点における抵抗低減コンセプトの妥当性が定量的に検証された。しかしながら、表面静圧分布や空気力特性の1部の飛行実験データにはまだCFD解析結果や風洞試験結果との不一致が見られ、現在もその原因については検討を続けている段階にある。最後に今回の飛行実験により得られた技術を適用して想定実機スケールのSST(SuperSonic Transport)形状の設計を行い、実機スケールにおいて巡航マッハ数と設計揚力で13％の揚抗比改善効果の得られることを確認した。, JAXA Research and Development Report, 宇宙航空研究開発機構研究開発報告

An experimental study was conducted to investigate transition process on 10-deg cone. There are two goals of this study. One is to validate transition prediction numerical code LSTAB, which is recently developed. Instability wave is detected by use of flush-mounted a pressure transducer and a hot-film sensor, and its frequency is confirmed to agree with the numerically predicted value. The second goal is to clarify the effects of freestream acoustic disturbances on the boundary-layer transition in supersonic flow. Intensity of freestream disturbances was controlled by a strip of sand paper or distributed roughness, which were attached on the floor or sidewall near the throat. High-frequency disturbance increased in freestream when sand paper was attached on the floor, though freestream disturbance was not affected by larger roughness on straight sidewall. The effect of roughness on the wind tunnel wall is pointed out to be different with the position and condition., Special Publication of National Aerospace Laboratory, 航空宇宙技術研究所特別資料

JAXA is planning supersonic flight tests in the middle of the 2010's by a newly designed unmanned supersonic airplane named "Silent Supersonic Technology Demonstrator(S3TD)" to demonstrate JAXA's original low boom concepts and its design technologies. 2 year preliminary designs of the S3TD and the ground segments including the sonic boom measurement system have completed. The autonomous S3TD weighs 4.2ton at take off and mitigates its sonic boom at Mach 1.4 to 1.6. The flight tests are planned 30 times or more at Woomera Prohibited Area of Australia. This paper describes the system requirements and the preliminary designs results of them., 宇宙航空研究開発機構では,将来のブレイクスルーとしての超音速旅客機実現を目指し2005年10月に飛行実験に成功した小型超音速実験機(NEXST-1)に引き続き,新たな飛行実験プロジェクトとして,2006年度より｢静粛超音速研究機｣(S3TD:Silent SuperSonic Technology Demonstrator)の予備設計に着手し,2008年～2009年度に基本設計を実施した.S3TDは,完全自律離着陸及び超音速飛行可能な無人機で,ソニックブーム低減技術を飛行実証することを目的としたものである.本報告書では,超音速飛行実験計画及び飛行実験システム(研究機システム及び実験場システム)の設計検討について,JAXAが独自に検討した成果及びJAXAとプライムメーカの契約に基づき実施された成果をまとめる., Original contains color illustrations, 形態: カラー図版あり, 著者人数: 32人

基準形状に正弦波状，あるいは局在する波状の変形を加えることで，超音速自然層流機首を設計することを試みた．変形のパラメータだけでなく，一様流に関するパラメータも変化させ，最も自然層流効果の大きくなる形状を調査した．その結果，変形によって周方向と軸方向の圧力勾配比が減少すると，側面の境界層遷移を支配する横流れ不安定を抑制し自然層流効果をもたらすことがわかった．また，この圧力勾配比を小さくするには，圧力分布のピーク位置，すなわち圧力係数が負圧側で極大となる位置をトップラインとボトムラインで適切に配置することが重要であることがわかった．そして，そのような自然層流効果をもたらす変形形状の設計指針を獲得し，自然層流機首となる形状例が得られた．正弦波変形における自然層流効果は，実験的にも検証できた．一方，全抵抗の増加を抑制するには，局在波変形の方が有効であることが示された．, The transition characteristics were examined numerically on candidate shapes in order to design a natural laminar flow nose for a supersonic transport. Two types of deformation from a baseline shape were examined. One is sinusoidal type, and another is localized type. Not only parameters of geometry which define the deformation, but also the conditions of uniform flow were varied to obtain the largest effect of natural laminar flow. In results, the crossflow instability, which dominates the boundary-layer transition at the side area, was found to be suppressed from the small ratio of pressure gradients in azimuthal and axial directions at the side area. Moreover it was found that the relative location of bump in pressure distribution along leeward and windward rays is a key to yield small ratio of pressure gradient in azimuthal direction. The effect of natural laminar flow for sinusoidal deformation was confirmed experimentally. On the other hand, the localized deformation was found to be more effective in order to suppress increasing of total drag than the sinusoidal deformation., 形態: カラー図版あり, Physical characteristics: Original contains color illustrations

Flight test of a supersonic experimental airplane was performed by Japan Aerospace Exploration Agency to improve advanced aerodynamic design technologies for the next generation SST. The experimental airplane was designed to reduce the drag on a supersonic cruise condition. Surface pressure distributions, boundary layer transition locations and aerodynamic forces in the flight test were obtained to demonstrate the aerodynamic design methods and tools. The flight test results evaluated by comparing with the prediction results obtained by CFD based optimum design tools. The flight test results relatively corresponded to the CFD results. Aerodynamic design concepts for drag reduction were demonstrated qualitatively and quantitatively by the NEXST-1 flight test., 形態: カラー図版あり, 会議: 小型超音速実験機（ロケット実験機）飛行実験データ解析完了報告会(平成20年7月10日. 東京大学山上会館)

A database for aerodynamic design of the supersonic transport (NEXST-DB) was constructed by JAXA. Many kind of aerodynamic data uploaded on the NEXST-DB were accumulated from the NEXST program. The uploaded data on the NEXST-DB consisted by aerodynamic results, airplane geometries, aerodynamic design tools and publications. A fl ight test, CFD analysis, wind tunnel test and the boundary layer transition analysis results obtained from the NEXST-1 project were mainly uploaded as the aerodynamic results. The aerodynamic design tools were developed on the project and used for designing of the NEXST-1 airplane. All of the aerodynamic data and tools uploaded on the NEXST-DB can freely be downloaded from the website. The detail information of the publications related to the NEXST program was also introduced., 次世代超音速旅客機の研究開発として進められた小型超音速実験機(NEXST)プログラムにおいて蓄積された空力データを収録した超音速機空力設計データベース(NEXST-DB)を構築した．インターネット公開型のデータベースであり，Web上で図示機能やテキストデータのダウンロード機能を充実させ，正確なデータが迅速に利用できるようにした．本NEXST-DBには空力データ，機体形状データ，空力設計ツール，そして対外発表資料を掲載・公開している．空力データには，NEXST-1の飛行実験や，CFD解析，風洞試験，境界層遷移解析結果を掲載し，機体形状データはCAD形式の形状ファイルが利用できるようにした．空力設計ツールは，NEXST-1の空力設計に用いた抵抗低減設計ツールやCFD逆問題設計ツールを掲載し，利用の多様化を図った．掲載内容や機能，利用方法の詳細についてまとめた．, Physical characteristics: Original contains color illustrations, 形態: カラー図版あり

In the aerodynamic design of the National EXperimental Supersonic Transport (NEXST) program, a supersonic natural laminar flow (NLF) wing design concept was originally developed. Before the flight test of the NEXST-1 airplane, more detailed transition analysis should be performed in order to validate the NLF wing effect. Therefore, the JAXA-ONERA cooperative research project started in April 2000, because ONERA had great ability of analyzing transition phenomena and JAXA had some experimental transition data in supersonic flow. In the transition analysis on the sharp cone with a half angle of 5 degrees, the nose cone, and the NLF wing of the NEXST-1 airplane, good cross validation of both ONERA's and JAXA 's e(N) codes was obtained. There was also high correlation between the experimental results in ONERA's continuous circuit-flow type supersonic wind tunnel and both laboratories' predictions under the assumption of a critical transition N value of 6. In addition, a risk of transition due to attachment-line contamination was predicted at inner wing, using the well-known Poll's criterion., Original contains color illustrations, 形態: カラー図版あり