This forum is about wrong numbers in science, politics and the media. It respects good science and good English.
Sorry. There is an engineering problem to solve: How to get people from point A to point B. There is a marketing problem to solve: How to get people to use the engineers solution.
Your analysis is correct.
The human powered helicopter is an example of a great trick. Some of the lessons learned can transfer over into other areas, but mostly it is a great way to focus on a particular part of the problem.
I tried to explain to my son this morning why it was that two umbrellas broke over the last year. We had purchased both of them at the Thrift store. They were both used. Part of the attractiveness of the umbrella is its lightness, that allows it to be carried in a backpack without undue burden to be available for the minutes when it is needed. If it were sturdy enough to handle all things forever, it would likely be really heavy and not so conveniently carried.
Handling all things is hard to quantify when you have a 9 year old and an umbrella that "springs" open at the press of a button.
The umbrella cost $1. The next one will likely be close to the same. I don't freak out when the umbrella is opened 20 times in 10 minutes when the price point is $1.
The Solar Impulse Proejct is not $1.
I am reminded of the great marketing bonanza surrounding the Prius and the vilification of "gas guzzling 4x4s".
What was carefully omitted from the evaluation of the Prius was the fact that it needed special steels to carry the weight of those batteries which are a life limiting factor.
If one only focused on the cost of fuel and the pollution emitted in use, as one was supposed to and being lead to do by the marketing, then the Prius was the future. The best thing since sliced bread.
But of one looked at the "ashes to ashes" energy content and pollution, top of the league for the most environmentally friendly vehicles came, you guessed it, a gas guzzling 4x4 with Prius somewhere down in 84th p[lace or something.
The 4x4 uses all standard materials and its engine, being oversized for the task in hand (taking the kids to school mostly, or so it seems) last practically forever. Long enough so that its "footprint" is vastly more favourable.
Thus one wonders what we are not being told about the solar project. Obviously weight is a factor.... (is this what I recall from 12 years or more ago? wasn't their some circumnavigation flight that was going to be man-powered? I need to look into it.) so what are the materials used? Very light weight films from petrochemicals? Oops!
PS. With the BBC as it is today is it safe to segregate the "scientists" from the "Climate scientists"?
"Separate the scientists from the climate scientists?"
Are you suggesting that real scientists may start distancing themselves from the climate scientists?
This makes me think of a cartoon. Cell one shows the scientists cringing away from the climate scientists. Cell 2 shows the climate scientists basking in the glow of the "Fear they perceive" in their fellow scientists. "They are scared of our knowledge, we have power!"