I just got the new Flight Vidoe Productions Columbia 400 video, and upon learning it was a piston engine aircraft, was surprised to see it is certified to I think, 25000 ft. I am only a sim pilot, and thought piston engines were only good in the lower altitudes, with higher altitudes requiring turbine engines. Could somebody please clarify? Thanks. Tom

It's a great vid, I have it also.I thought that was a normal altitude for most piston engines these days. I might be wrong though.That still doesn't relieve the responsibility of crew/pax Ox above what the FAA says, of course.* Edit: I should clarify what I mean by 'normal': By that I mean the 'normal' certified ceiling, not the 'normal' cruise alt..

You are correct. Normally aspirated engines, as fitted to regular Cessnas, Pipers etc. lose manifold pressure with altitude, at a rate of roughly 1" per 1000ft. This limits the altitudes at which they can operate.The Columbia 400 is turbocharged to cope with the higher altitude (it actually has twin turbo chargers fitted, one for each side of the engine.) Think of it as a high powered fan forcing extra air into the engine. Turbochargers/superchargers have been use on aero engines since way back, when they had a manual 'boost' control.You'll also see some planes (Cirrus have one) that are 'turbo normalised'. These will maintain sea level pressure (~30") to a higher altitude, before the normal lapse rate kicks in, whereas fully turbocharged engines can maintain maximum MP right to their ceiling.

>You'll also see some planes (Cirrus have one) that are 'turbo>normalised'. These will maintain sea level pressure (~30") to>a higher altitude, before the normal lapse rate kicks in,>whereas fully turbocharged engines can maintain maximum MP>right to their ceiling.I've never seen an engine that maintains full MAP all the way to the service ceiling of the aircraft. Turbocharged aircraft have a critical altitude where the compressor can not maintain its maximum power output and this is where power begins to fall off and then you reach the service ceiling and then the absolute ceiling of that aircraft. The only real difference between turbo normalizing and turbocharging is that the charging aspect is to create a higher manifold pressure then normal for more power. Normalizing is not used to create excess power but instead to maintain that power to higher altitudes.

That's the way I understood it also. Manufacturers always advertise the 'tested' to limits; or 'certified' to limits when talking about their aircraft.I was always taught that turbo charging was for efficiency and and super charging was for speed.It just so happens though in the case of the Columbia and others in the homebuilt to> production class seem to narrow that gap a little at gross. Even so, when loaded and with temp and winds, etc., factored into the equation, the same rules of physics still apply.

>I was always taught that turbo charging was for efficiency and>and super charging was for speed.Take a read at chapter 5 of the aeronautical knowledge handbook here and it can explain the differences in more detail.http://www.faa.gov/library/manuals/aviatio...083-25-1of4.pdfIn a sense you are correct about efficiency on the turbocharging. Both turbocharging and supercharging do the same things but by a different means of producing that compressed air.

Chris,LOL, remember, I've been through that also.That's also a good link to look at. It should point out that there are also differences in now only how they work as you state by when they intake/compress the air, but also where they might be placed to acomplish those tasks. Of course differs throught the era's as well.For pilots/owners though, when listening to manufacturer verbage, they need to understand that turbo charging doesn't mean more speed (per say), but more importantly the benefits that a turbo charger can provide in terms of 'possibly' more payload, efficiency (in several ways as you touch on) etc., etc., etc.; and that a turbo charger does not mean you just leave the power at the firewall all they way up to cruise unless you enjoy spending money to replace those items...hehe.*Edit: this a great topic to talk about, btw :-)

I just got this video as well and my god what a sexy plane . . . and a cute sales manager :}

Agreed. She can fly with me anytime!!!:D Tom

Actually, some turbo charged piston engines can do better than turbo props at higher altitudes.I've flown a friend's Columbia 400, and it is an amazing aircraft. I also fly a Cessna Turbo 210 a couple times a month, and its service ceiling is 27,000', but it can go higher, much higher. A Cessna turbo 210 once held an altitude record for its type (which it recently lost), I believe its record was something close to 43,000'. For the most part, while we can fly these planes at such high altitudes, it is not really wise, as you are really pushing the engine. In FS this means nothing, but in real life it might mean a $50,000 engine overhaul several hundred hours before you expect it. Or a $20,000 "top" overhaul after a few hundred hours.For the most part, if one does not want to throw money away, most turbo charged piston aircraft are best operated in the "teens", perhaps with 20,000' as a limit. If you need to go higher, the ability is there, but you would be wise not to do it all the time.Otherwise, operating a turbo charged piston aircraft does require some finesse in real life if you even wish to hope to get to TBO with the engine. ;) Regards,http://www.dreamfleet2000.com/gfx/images/F...R_FORUM_LOU.jpg