Recent content by merriam

Actually, Hydrogen has an energy density (per kg) of approximately 3 times that of jet fuel (varying slightly with temperature) and at least 100 times that of Lithium polymer batteries. However, it is tough to use. Among its drawbacks: Takes a lot of volume store as a gas, though hydrogen...

To some degree, transmission lines can replace To some degree, transmission lines can replace generating capacity or energy storage. The sun is always shining somewhere and transmission of power can overcome the dark. But transmission lines cost money and will usually charge for their use...

Energy storage affects range. Jet fuel has an energy density of about 43 MJ/kg. A fully charged lithium battery can manage about 1MJ/Kg on a good day (maybe half that on an average day). There is a big difference. That means that if your aircraft allocates 1000 Kg for "fuel", you can go...

I stand corrected. At the Paris Airshow (june 2019) an electric aircraft was offered for sale. 3 engines, propeller driven, 650 miles at 500 miles/hour. 9 passengers. $4 million each. Roughly a dozen orders.

Lift is about 1 gram/liter. Let's call it 100,000 metric tons or 100 million Kg = 100 billion grams = 100 billion liters. Roughly speaking, a cube that is 1500 feet on a side.

The key to getting a flyable aircraft is the power/weight ratio of the engine. For Jets, the power outlet depends a lot on the speed, but roughly speaking a Boeing 777 engine (GE 90) puts out about 6 hp/lb (10 Kw/Kg). Very good electric motors can manage power/weight in this neighborhood...