Turbos altitude advantage

JamesC · #1 03-02-16, 04:57 PM

Single engine service ceiling numbers are attached for a 1971 (non-turbo) Skymaster. Just to illustrate as an example, today it is +70 deg F at Sedona airport (4830 ‘ asl) and say an engine fails at max gross after take off. In a turbo model you will be climbing at ~ 240 fpm. According to the attached table, in the 1971 model you will have to descend. Obviously those who fly the non-turbos already know this. This also implies that say it is 80 deg F and humid, you will be lucky to maintain even 4000 feet at max power if an engine fails. Anecdotes re turbo vs non-turbo are entertaining, but the only anecdote that really matters is the one that you got yourself into when those Swiss cheese holes line up.
So like anything in flying you have to weigh the pros and cons (for turbos cons include the weight, the cost of maintenance/repair/overhaul, you have to be more careful with MP settings and treat them right, and it’s another thing that can fail in flight), and make your choice. Personally I chose turbo for all the reasons in the P337H tables attached earlier.

YankeeClipper · #2 03-03-16, 04:29 PM

Quote:

Originally Posted by JamesC

Just to illustrate as an example, today it is +70 deg C at Sedona airport (4830 ‘ asl).

Yikes ... sure hope that's a typo.

JamesC · #3 03-03-16, 06:19 PM

Fixed it thanks for your feedback.

Larry Price · #4 03-03-16, 11:55 PM

Hmm...+70C is about +158F...and here I thought Texas was hot!

B2C2 · #5 03-04-16, 02:19 PM

I have a 1969 T337D with a Robertson kit and I have to say I totally agree with N86121. The airplane is just amazing. Climbs without hesitation up to 19000 ft, which is the highest I've taken it so far to get over the Rockies. Lifts 850 lbs with full fuel. And the engine out service ceiling is 19k ft on the rear engine, 16k ft on the front. So I can lose an engine over the Sierras and basically coast into Livermore where I am based. Every once in a while I look around for other airplanes and keep coming back to the T skymaster. In the west I would not want a non turbo airplane. A P model might be nice though....

YankeeClipper · #6 03-04-16, 09:13 PM

Some great info here. Though I am largely a flatlander (here in the northeast our tallest hurdle is 6288ft, and a standout at that), as my opener mentioned I have put some stock in the discussions various and wide about climbing above IMC conditions. I'm not especially stoked about the extra cost of maintenance, but our weather here is (in)famously unpredictable. Guess I'm pretty much sold on the idea of a turbo at this point. I'd still love to hear any anecdotes from those who've found themselves with a sudden need to climb above weather.

Aboutwright · #7 03-12-16, 08:41 AM

I'm not quite sure of what you're aiming for in using the Skymaster.
What will be it's mission 80 to 90 percent of the time. Will it be mission critical (delivering human organs!) or personal (you can pick your weather).
I have been a corporate pilot for over 25 years and been blessed to have flown a variety of aircraft including jets. I've flown normally aspirated Skymasters and currently own a P337H. I fly it from northern Ohio to central Florida non-stop in the high teens at 62% to 65% power and it gives me 180kts with plenty of reserve fuel. I can say that the previous comment about the extra power to climb above icing is good, especially if there is high terrain below, but it is only good if your flight is going to take you beyond those conditions or you will just be decending back through it.
Cruising above 10000ft will definitely put you in smoother air above the thermals of a hot summers day and a normally aspirated Skymaster will easily do that, although not quite as quickly as a turbo. Other types of convective activity comes in many shapes and sizes and many cannot be topped by any type of Skymaster!
In respect to the TSIO-360's longevity, I agree that ANY engine will reach TBO more easily in the hands of a smooth pilot and not a throttle jocky, especially the turbo'd versions. Also it is critical for a turbo'd engine to be set-up or tuned correctly to live long and be happy. Items such as unmetered fuel pressure, metered fuel pressure, turbo wastegate settings, and spark advance need to be adjusted correctly in relation to each other, and require a mechanic with the experience and the tools for the job.
But getting to the point. It sounds to me like you are looking to buy your first Skymaster? If that is the case and most of your flights are not long or "mission critical" I think you would be happy with a nicely equipped normally aspirated version. Save a little on maintenance costs now and get to know the breed. Trade up later if you feel the need.