Peter wrote:
The trouble is that with TB20 you climb around 200-300fpm above FL120
Something not right there. A TB20 does 1000fpm at sea level, 500fpm at 10000ft and 0 fpm at 20000ft. I see 200fpm at FL180 or so. This needs best power i.e. max rpm and 150F ROP (usually about 1300F EGT, at altitude).In reality I choose to climb a lot slower; peak EGT if possible because then the climb doesn’t cost significant fuel and it keeps the CHTs down.
Comparing apples and oranges here. I say 200-300fpm above FL120 and you say values for FL100, FL180 and FL200. Hard to compare. When I say 200-300fpm above FL120, it might be 300fpm at FL120 and close to 200 at FL140. All depends on TOW and ISA conditions. I just wanted to say that NA engine climb is very MARGINAL. I would like to see something like 800-1000fpm at altitude (above 10000ft up to at least FL180, possibly even higher if needed). I would also like to see normal manifold pressure at altitude and not 17". With this normal manifold pressure comes nice true airspeed, which you lose with NA engine with altitude. I would say that TAS goes down with NA engine above 10000ft (and probably sooner, would have to look into POH).
No question that a turbo does wonders for the climb rate and the ceiling. For this oxygen system test I was in a turbo Saratoga and it was doing +1000fpm at FL180.
The issue comes down to personal preferences regarding e.g.
and IMHO that is really what this thread is about. Nobody is saying that a turbo doesn’t work.
I could write a cheque for a TB21 anytime but
Your TKS will reduce payload by 50kg + as well :-)
Then you get the discussion of whether flying with a turbo leads you to flying more in icing conditions 
For sure it does allow you to escape a given level of icing conditions more quickly, but that’s because a climb is not very often – at GA levels – limited by ATC clearance. Sometimes it is however… out of Shoreham, going east, you won’t get more than FL100 until Belgium, and you can’t go south east because it is all French military areas. The other and probably more relevant scenarios I have found where you would be exposed to prolonged icing and could do little about it, turbo or not, is when flying approaches in IMC, in the winter. Therefore, what really makes sense is turbo and TKS together. But a TB21 with both has an empty weight of ~1000kg and with an MTOW of 1400kg it is a 2-seater if you are going any distance. These are the tradeoffs. That is one reason why the SR22T sells.
That is what I wanted to say – SR22TN or Bonanza. Piston Socata is not the only airframe in the world. It is a great tourer, very comfortable, very good ergonomics, very good endurance, no problem with long flights (you are the living proof here :-)) but it has its limitations. I am sure that you could live with TB21 as you typically fly alone or two up. For me, TB21 with TKS and Turbo might be a bit limiting on payload but the older the kids are the more I see we typically fly two up only, occasionally three up so even TB21 might be a solution for me.
My TN added 80 lb to the empty weight and the O2 added 20 lb.
Obviously jets are not stuck at FL100 going to Belgium, so in a way your aircrafts inherent performance is what limits you also from getting a higher FL and being able to get above wx. If you filed every IFR flight plan at FL250 in a Cirrus, you’d probably get higher FL’s much quicker and minimize having to slog around in the sleet, but people don’t do that.
No doubt that a turbo installation is more expensive which is also reflected in the initial purchase price on a given aircraft with/without turbo. Its simply more complex with added components. This difference shows again at the overhaul and to some degree in the maintenance period in between. Extra items like wastegate and turbo must be inspected during annual. But a turbo engine does not necessarily have to work much harder than a normally aspirated engine. The pilot has a throttle to control that.
When I fly my RV8 which has a NA IO-360A1B6 it will hit 75% power at around 8000 feet at full throttle which is a good cruise altitude for that aircraft. In my TB21 apart from first few minutes of flight I also operate the engine at 75%, but I will keep the 75% all the way up and then settle for cruise at 65-75% normally at FL 180. This is exactly the same work a normally aspirated engine has to output at lower levels in many cases. There are two main differences though. The first one is that thin air cools less than dense air lower even though its colder up high. The second is the air inlet will be warmer as it has passed compression from the turbo. These two things put together means a higher cylinder temperature. But to counter this (at least to some degree) the turbo aircraft designs has arrangements to improve cooling. Cooling flow can be increased by adding cowlflaps and/or larger inlet areas in the cowling.. Compare cowl of a NA mooney vs Turbo mooney fx. Or as the case is with the TB21 a much larger exhaust than the TB20 essentially severing as heat sink.
I try to treat the engine good and I believe it pays off in the end. But for sure a turbo engine is more prone to misuse from the pilot (over leaning by forgetting the mixture, shock cooling during long decends with low MP ect). I believe a fair share of the turbo engines having problems are from pilot misuse. In some cases maybe also poor engine design or implementation on the airframe. Fx I remember reading about Mooney having some issues long way back with a Lycoming model that needed a modification to have the cylinder heads oilcooled.
But on the positive side of things the turbo provides options. The way I see it, just because you have a turbo doesn’t mean you have fly in know icing or at FL250 all the time. But it provides more options to avoid and top weather if needed along with better cruise performance for same airframe/power setting. So I think a thread like this is potential good info for somebody considering investing in aircraft for travel. I more or less by coincidence bought an older TB21 (pre GT) over other NA aircraft. Today I see what a big difference the turbo makes to my IFR mission. So like Pytlak experience shows its worth seriously considering the pro/cons of the turbo and compare with ones mission profile or potential future mission profile (IFR?). Its one of the things that can be hard to change on the aircraft later on unlike avionics, interior, paint ect.
Obviously jets are not stuck at FL100 going to Belgium, so in a way your aircrafts inherent performance is what limits you also from getting a higher FL and being able to get above wx. If you filed every IFR flight plan at FL250 in a Cirrus, you’d probably get higher FL’s much quicker and minimize having to slog around in the sleet, but people don’t do that.
The airliner traffic into EGKK, around DVR, with EGKK on R26, is mostly c. FL150-200 (look at FR24) hence you can’t get into that stream. I guess if one can climb at +3000fpm then one can get merged in, but you would be climbing in the opposite direction. And I bet London Control has a policy on piston GA anyway, keeping it away from the “professionals”.
But a turbo engine does not necessarily have to work much harder than a normally aspirated engine. The pilot has a throttle to control that.
I am sure it works much harder in reality, because most people use the turbo they paid for Most turbo owners I know fly c. 75% power. However, we did this before. Also here – a quite informative turbo thread
Peter wrote:
The airliner traffic into EGKK, around DVR, with EGKK on R26, is mostly c. FL150-200 (look at FR24) hence you can’t get into that stream. I guess if one can climb at +3000fpm then one can get merged in, but you would be climbing in the opposite direction. And I bet London Control has a policy on piston GA anyway, keeping it away from the “professionals”.
I don’t think that is true at all. In the Mirage I was flown in London Control airspace all around other aircraft. Obviously they won’t climb you into descending traffic for Gatwick. They would climb you either North or south (presumably South in your case). For me out of Oxford they take you to DTY then East or South of Heathrow inbounds then East (along L9). I think UK ATC treat piston GA very fairly – subject to things like glide clear rules which are not imposed by them.
And I was always able to get an level from FL200-FL240/250 if I wanted it.
