The single flapping rotor: detailed physical explanations

A motor-driven helicopter rotor generates a reaction torque. This torque would accelerate the airframe of the helicopter about the yaw axis opposite to the rotor rotation if no measures are taken to compensate it. In the early days of helicopter development, a diversity of measures was considered: Henrich Focke has discussed these different measures. Not well known is a torque compensation measure which is restricted to only one main rotor, thus skipping the tail rotor or any additional rotor as well. This principle is worth looking into the details of the physical mechanism involved. The German scientist Prof. Hans-Georg Küssner of the AVA-Göttingen, Germany (Aerodynamic Research Institute with heads at this time: L. Prandtl and A. Betz) was the first to study the method successfully. He constructed a wind tunnel model and showed that the reaction torque could indeed be completely compensated. The present author has reviewed Küssner’s experimental data and could show that numerical calculations are in good correspondence with the measured results. In the present paper, the details of the method to compensate the reaction torque will be discussed. Corresponding numerical data will be presented taking into account Navier–Stokes calculations on rotor blade sections. Blade element theory will then be applied and combined with the Navier–Stokes data. Calculated forces and moments of a complete four-bladed helicopter rotor will be presented

Phase Ib evaluation of a self-adjuvanted protamine formulated mRNA-based active cancer immunotherapy, BI1361849 (CV9202), combined with local radiation treatment in patients with stage IV non-small cell lung cancer

Background: Preclinical studies demonstrate synergism between cancer immunotherapy and local radiation, enhancing anti-tumor effects and promoting immune responses. BI1361849 (CV9202) is an active cancer immunotherapeutic comprising protamine-formulated, sequence-optimized mRNA encoding six non-small cell lung cancer (NSCLC)-associated antigens (NY-ESO-1, MAGE-C1, MAGE-C2, survivin, 5T4, and MUC-1), intended to induce targeted immune responses. Methods: We describe a phase Ib clinical trial evaluating treatment with BI1361849 combined with local radiation in 26 stage IV NSCLC patients with partial response (PR)/stable disease (SD) after standard first-line therapy. Patients were stratified into three strata (1: non-squamous NSCLC, no epidermal growth factor receptor (EGFR) mutation, PR/SD after ≥4 cycles of platinum- and pemetrexed-based treatment [n = 16]; 2: squamous NSCLC, PR/SD after ≥4 cycles of platinum-based and non-platinum compound treatment [n = 8]; 3: non-squamous NSCLC, EGFR mutation, PR/SD after ≥3 and ≤ 6 months EGFR-tyrosine kinase inhibitor (TKI) treatment [n = 2]). Patients received intradermal BI1361849, local radiation (4 × 5 Gy), then BI1361849 until disease progression. Strata 1 and 3 also had maintenance pemetrexed or continued EGFR-TKI therapy, respectively. The primary endpoint was evaluation of safety; secondary objectives included assessment of clinical efficacy (every 6 weeks during treatment) and of immune response (on Days 1 [baseline], 19 and 61). Results: Study treatment was well tolerated; injection site reactions and flu-like symptoms were the most common BI1361849-related adverse events. Three patients had grade 3 BI1361849-related adverse events (fatigue, pyrexia); there was one grade 3 radiation-related event (dysphagia). In comparison to baseline, immunomonitoring revealed increased BI1361849 antigen-specific immune responses in the majority of patients (84%), whereby antigen-specific antibody levels were increased in 80% and functional T cells in 40% of patients, and involvement of multiple antigen specificities was evident in 52% of patients. One patient had a partial response in combination with pemetrexed maintenance, and 46.2% achieved stable disease as best overall response. Best overall response was SD in 57.7% for target lesions. Conclusion: The results support further investigation of mRNA-based immunotherapy in NSCLC including combinations with immune checkpoint inhibitors. Trial registration: ClinicalTrials.gov, Identifier: NCT01915524

Pitching Airfoil Boundary Layer Investigations

The present paper describes an experiment performed in a transonic wind tunnel facility where a new test section has been developed especially for the investigation of the unsteady flow above oscillating airfoils under dynamic stall conditions. Dynamic stall is characterized by the development, movement and shedding of one or more concentrated vortices on the airfoils upper surface. The hysteresis loops of lift-, drag- and pitching moment are highly influenced by these vortices. To understand the very complicated unsteady flow involved, a detailed knowledge of the instantaneous flow fields is of crucial importance. With the application of the described measuring techniques it is expected to gain more insight into the problem. Results from these tests are ready for comparison with numerical data

Adaptive Airfoil

"Adaptive Airfoil" is the title of an EREA project launched in January, 1998 with the participation of CIRA, DLR, FFA (now FOI), INTA and ONERA. The main objective of the project is to demonstrate the feasibility and to quantify the benefits of adaptive wing technology. Of the various ways to achieve wing adaptation, i.e. variable camber, suction/blowing, etc. the addition of surface bumps to the original airfoil geometry is an additional possibility. It has been shown recently that the combination of two bumps located at the position of the sonic line and close to the shock foot respectively leads to remarkable improvements with respect to drag reduction and buffet control. Research work in the field of aerodynamics of supercritical airfoils including dual bump systems has shown that beside of the location of the bumps along the upper wing surface, the fine tuning of shapes, height and their time dependent variations are of importance to successfully achieve the objectives. Numerical as well as experimental investigations have been carried out within the scope of the present project

The Flapping Propulsion Rotor - Single Rotor without Tail Rotor

The term “Flapping Propulsion Rotor” has first been used by H.G. Küssner in Germany in the 30ies of the last century. Based on a patent, Küssner has developed a wind tunnel model to demonstrate his concept of a rotor with a tip path plane tilted against the rotor axis. He could show experimentally that with this arrangement the reaction torque of the rotor could completely be compensated. The rotor then works without any additional device like tail rotor or second counter rotating rotor. In the present numerical investigations it will first be shown that the flapping rotor test data match sufficiently the calculations. Extending the concept (which Küssner had already proposed) to a combination of flapping and pitching blades it will be demonstrated that then the efficiency and range of applicability can be improved consid-erably