I've enjoyed the posts. This is my .02 when it comes to cost-benefit and efficiency.
It occurred to me one day when I had the choice of flying east one beautiful day when I had no wind up to 15k' [okay, maybe 3kts] for a 200nm trip in my C-150. No one ever taught what altitude to fly for best efficiency, government this, regs that, etc... What was the best alt from gnd-effect [not possible for the obvious terrain changes] to 15k'? Yes, my 150 would make it! Whats the best fuel consumption altitude? I won't address speed for this particular post as it?s a fine line to opening up different discussion altogether. I'll just post you what I have done as it helps answer to turbo, or not to turbo. I have access to a few planes POH's: my C-150, a twin comanche, a turbo twin comanche [normalized only], C-210 [turbo >35in single], and a good ole gas-drunk piper apache! I felt crazy plotting these data because no one can answer my question as to what alt. and speed to fly at to earn the most MPG in a no wind environment and explain why. Is climbing for the TAS benefit worth it? in short, no. Turbo is closer to fuel saving however, and this surprised me. Over the next probably 20hrs of flight planning scenarios [excited new pilot has this energy], I planned my own trip I faced that day with each plane, and again for flights at 1k,3k, up to ceiling, and svc. ceiling. Parabolic ascents, descents, jet-type ascent/descent profiles, etc. After that, I planned full fuel tank burn for each plane. Aside from the predicted ground effect winning efficiency in all cases, I found its best to stay as low as possible because the fuel spent climbing does not earn its keep for the TAS payoff when climbing to altitude for a no wind condition. I tried different climb speeds, etc to cover all angles. I learned much in the process. Two upsets though: The turbo planes [both normalized and boosted] climbing to their high cruise altitude provided to be equally efficient as the NA planes that didn't climb. They were in turn faster in the process as well. the turbo's payoff occurs when the tanks are fully used because its more time spent at altitude benefiting from the TAS gain. Now does fuel price offset the price of the turbo? That depends on how much the pilots time is worth. My opinion, is that the cost of the turbo, certified and experimental application is not worth the benefit regarding effieciency. On the other hand, if you live on an ocean island would you want a turbo? What if you lived in the Rocky mountains? Envrionment and safety can persuade otherwise and other people have posted positives and negatives I won't repeat here. At Oshkosh last year, I talked to a guy named Jer from Colorado in the Cessna Pilots Assoc. I flew in with that is a CFII, and specializes in mountain flying instruction. If you look him up, you didn't hear he was an 'old guy' from me :) He also does not desire turbos and this lead to an interesting conversation of mountain flying in normally aspirated planes because I'm near the smoky mountains. Contact me and I'll flip you his email from his biz card if you care to share a conversation like I did. My twin turbo Nissan 300zx is just an experience everyone should enjoy. I do like turbos. They are fun! I like the power if the engine can withstand it like the car can. Having a turbo on a twin and losing an engine in Idaho is better than crashing because single engine performance is not what the poh says when you need it most. Seeing a kr with a turbo definitely is sophisticated, complicated and something to be proud of because it does have its element to once again, outperform a certified plane in all regimes. Cost-benefit? eh, when it all comes down to it, as an airport manager, I see too many obstacles to general aviation to warrant making a plane that takes great sunset pictures endure less flying time because a more complex system requires more maintenance and threatens the pilot with added cost and time. Get em flying! Andy
