After takeoff the 421 just climbs about 700FPM all the way up to flight levels. slow and steady. Wastegates close seamlessly and it just keeps pulling. No mixture changes. Throttles hold in one position and the controllers do the work. No cowl flaps to mess with. Temps never seem to be an issue.

It will out climb the Kingair E90 I also fly now on hot days and low flight levels.
I think the 421 is nicer handling especially during the landing flare than the 90.

I never had a 421 above FL230. I didn't think it made sense for the fuel burned to get there.
I am typically 16K to FL210 depending on the wind. Higher if I can get a tailwind.

I often get great routing because where I fly there is less traffic in the mid to upper teens a lot of the time.

421EE was happy climbing to FL270 at gross. It did have the winglets, so 3' longer wingspan, not sure how much difference that made.

That says more about the King Air than the 421.

I didn't realize the E90 was that lame in climb.

Mike C.

I should clarify Loaded hot day down low the Kingair easily beats the 421 in climb until above FL180 then I think the 421 climbs faster. Especially if trying to get on top and the Kingair has the ice vanes extended. This is E90 with -28s. no winglets. Raisebeck gross weight increase, 4 blade hartzells, full gear doors, strakes and wing lockers.

E90 is faster in cruise low 20s and carries more by a lot. Also longer range. But 62 GPH, higher cost to buy and maintain. 421 has a better cabin differential so it can go higher than the E90. Best I can do with the E90 is FL 240 and the cabin is just below 10K.

The 421s I fly are B models with the original type toothpick McCauley props so a C or C with winglets and the paddle blade Hartzells might be better? But with the gross weight increase STCs it seems to be getting awfully heavy for the available HP.

I used to think you could totally rebuild a 421 to be really nice for the cost of one PT6 overhaul. With today's pricing and age probably not.

I wish support for the 425 was better.

On the East coast with ATC the 90 is much easier to manage. On descent it's easy. 421 requires some planning.

If you look at flightaware - seems like the 421's are going to FL200 or so and it is taking 25 minutes to get there.

I usually would count on about 25 minutes to FL250 from Denver area on the Aerostar. Many times we get restricted for a bit going eastbound, and I typically use 35" and 2400 for the climb. They certainly respond to the higher power settings, and most of my clients use 37" or better for the climb.

You are going to use about 145 indicated for the climb in the Aerostar, which compared to most of the others in the class will put you further downrange at the top of climb. Normally I see 1200 feet a minute or so climbing through 12,000 feet at a pretty good TAS.

After takeoff the 421 just climbs about 700FPM all the way up to flight levels. slow and steady. Wastegates close seamlessly and it just keeps pulling. No mixture changes. Throttles hold in one position and the controllers do the work. No cowl flaps to mess with. Temps never seem to be an issue.

It will out climb the Kingair E90 I also fly now on hot days and low flight levels.
I think the 421 is nicer handling especially during the landing flare than the 90.

I never had a 421 above FL230. I didn't think it made sense for the fuel burned to get there.
I am typically 16K to FL210 depending on the wind. Higher if I can get a tailwind.

I often get great routing because where I fly there is less traffic in the mid to upper teens a lot of the time.

Thanks guys. I mostly hang out around 16-20000 in my Silver eagle, but sometimes over the tall rocks in the southwest I've found I've needed to get a little higher to get through some ice and over weather so I was curious on the climb rates.

Garth

The TIO-540-U2A powered Superstars are legal to run full power up to FL200 according to the book. I am sure there is some sort of curve from there. There really is not much difference between the various engines that are installed on the Superstar I STC.

The challenge is always keeping the wastegates and exhaust system tight enough to be able to produce good power up high. Most people don't do that well.

They will do decently well from FL200-FL250 with the power pushed up. I have been up to FL280 with them and there is not much left. They do best in the low 20's.

I have owned a number of Turbo Twin Comanches over the years. They all would arrive in the same state short of one plane. You take the vernier controllers for the wastegates forward and you get 1-2" of MP increase over normally aspirated. That system is so lightly built that it is constant maintenance to keep the boost respectable. But I did buy one that came in with a well maintained turbo system that would get full power at FL200 - and it went well.

The Aerostar system is not like that, but you do have to pay attention to it if you want high power available to FL250. The standard I like to use is to bring it up to 35" at 2500 RPM at FL250. You can certainly do better - all it takes is time & money!