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  1. Dusan

    The Custer Arc ?

    They did test the lift at 'hover', see the table at page 10. For a project using channel wings for VTOL see here: https://hopflyt.com/
  2. Dusan

    The Custer Arc ?

    The benefit of the Custer wing comes from the wing top surface exposed to propeller accelerated airflow. This leads to several improvements, as artificially increasing the lift coefficient to very high values, stall practically eliminated at any AoA, and the wing producing lift even at zero...
  3. Dusan

    Wooden structure reinforced with carbon fibre

    I'm no structural engineer, but wouldn't carbon stiffness have all the loading transferred to carbon and the wood act only as 'foam'?
  4. Dusan

    Hydrogen generation use and storage.

    Hydrogen is not really an energy source. Ideally, extracted from water, theoretically the same amount of energy can be recovered by burning or used in fuel cells, but as the efficiency of those processes are low you spend much more energy than recovered. At best - the hydrogen is an energy...
  5. Dusan

    Why battery-powered aircraft will never have significant range

    Gasoline energy density is a bit under 13,000 Wh/Kg (wikipedia); the best lithium batteries have about 250Wh/Kg; that makes gasoline about 50 times more energy dense. The problem with batteries is that they carry all the reactants inside. 1 kg of gasoline needs about 15Kg of air to release that...
  6. Dusan

    New rotorcraft concepts

    Any edgewise rotor aircraft is having on it's best day a L/D equal to 5, but usually being about 2 to 4.5. This is regardless of the rotor being powered or not. Without transitioning to a wing-borne flight, the L/D cannot be improved and the aircraft ends up 'fighting gravity all the time'...
  7. Dusan

    EAA No Longer Has Free SolidWorks

    Has anybody experience in openVSP? It's a NASA development for initial aircraft analysis. From the website: "OpenVSP is a parametric aircraft geometry tool. OpenVSP allows the user to create a 3D model of an aircraft defined by common engineering parameters. This model can be processed into...
  8. Dusan

    Solder Splice Connectors

    To anyone that is considering extending the thermocouple wires - you need to understand that the thermocouple is measuring temperature difference, not absolute temperature. There is always a 'hot' and a 'cold' junction, as depicted in this picture from wikipedia: Thermocouples are usually used...
  9. Dusan

    New rotorcraft concepts

    Actually the GEN_H-4 needs abut 40hp to hover, and it's MTOW is half of the VZ-1
  10. Dusan

    New rotorcraft concepts

    Sure, but a hovercraft is not an aircraft. The VZ-1 needed about 50kW to hover, due to relatively large disk area and 40% of the lift was provided by the duct. Compare that to the 320kW Lilium jet or 1216KW of Ehang184
  11. Dusan

    New rotorcraft concepts

    I was always a fan of the Hiller flying platform, I liked the concept, an efficient personal hovering aircraft. Too bad they did not continue the project for non-military applications. One of the shortcomings was too much stability, having excessive pitch-up limiting the forward speed. I'm...
  12. Dusan

    AMPERe One stroke engine

    @PMD For the same weight, the energy contained in fuel is 40 times more than in a lithium battery, as a fact. About the one stroke engine - vaporware.
  13. Dusan

    Why Jets fly high and propellers can't keep up

    Everything about producing thrust is efficiency. How much of the go-juice you spend to generate thrust. Propellers are better at slow speed as it's more efficient to impart a small acceleration to a large air-mass. At high speed, turbofans are better since transonic blade flow is eliminated by...
  14. Dusan

    Why battery-powered aircraft will never have significant range

    I don't want to get into arguments, but facts are facts. Our current gasoline car engines have one of the lowest thermodynamic efficiency out there, about 20% to 35%. Taking into account also that the gasoline needs to be refined and transported, it is much better to use the oil to power a...
  15. Dusan

    Why battery-powered aircraft will never have significant range

    As per https://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/US-Fire-Problem/osvehiclefires.pdf there were 181,700 highway vehicle fires per years 2013–2017. Not sure how many were electric propulsion vehicles but I assume not many. As the battery gravimetric energy...
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