Absolute Single Engine Service Ceiling

caliginousface

caliginousface

Frank N. Beans
So I feel like a complete dumbass, but I'm not quite sure I've got this calculation down correctly. I remember something from ERAU telling me I'm supposed to slide the ISA line to the right and intersect the red arrows I've put on the attached chart, but I really don't remember.

It's from a Duchess POH, and I'm looking for Absolute SE service ceiling. Did I do this correctly?
 
I started to answer, then looked again... ???????????????

I haven't done that stuff in over two years!! I think the Seminole had a seperate graph, but I'm not sure. It looks good to me though.
 
Calm down man, the MEI was seriously the easiest checkride I have ever taken. Of course, the DPE I used was a "friend" of mine that I sent all my students to, and he may have taken it easy on me.
 
tgrayson said:
Service ceiling and absolute ceiling are two different things. Absolute ceiling is where you get zero fpm and service ceiling is where you get 50 fpm (single engine).
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Right I got that, hence the attached picture shows me trying to figure out at what altitude I would reach the Absolsute SESC. The confusion lies in my methodology in that at my short time at ERAU, they talked about moving the ISA line to find them using a Seminole POH, whose chart differs from the one for the Duchess.
 
tgrayson said:
Service ceiling and absolute ceiling are two different things. Absolute ceiling is where you get zero fpm and service ceiling is where you get 50 fpm (single engine).
Click to expand...

Mmmm I think my wording is what made you say that.

So what you're saying is I shouldn't be calling "Single Engine Absolute Ceiling" what I have been calling it: "Absolute Single Engine Service Ceiling."

Single Engine Absolute Ceiling being the 0 FPM.

Single Engine Service Ceiling being the +50 FPM.

So in other words you're lookin' out for me and teh semantix yo. Thanks man!
 
caliginousface said:
Mmmm I think my wording is what made you say that.
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Yes. I inferred that you might have thought that 8000 ft was an absurdly high service ceiling for a Duchess and hence distrusted your methodology. Sometimes a host of confusion results from a word slip. ;)

I get about the same number you do for the absolute ceiling.
 
caliginousface said:
Right I got that, hence the attached picture shows me trying to figure out at what altitude I would reach the Absolsute SESC. The confusion lies in my methodology in that at my short time at ERAU, they talked about moving the ISA line to find them using a Seminole POH, whose chart differs from the one for the Duchess.
Click to expand...

Oh, make sure you using OAT for the altitude in question. 30 degrees C for 8,000 is really, really hot for that altitude. Perhaps ERAU had you move the ISA line a tool to scale surface temps to standard temperature at altitude. I've never seen that done, but it seems a neat trick.
 
tgrayson said:
Oh, make sure you using OAT for the altitude in question. 30 degrees C for 8,000 is really, really hot for that altitude. Perhaps ERAU had you move the ISA line a tool to scale surface temps to standard temperature at altitude. I've never seen that done, but it seems a neat trick.
Click to expand...

Yeah I was trying to do the same thing with this Duchess chart and it doesn't work out.

And when you say for the altitude in question, I was assuming a 30 degree C surface temp at SL, putting the the Absolute Ceiling at 8000ish. Because I don't know what altitude the Absolute Ceiling is. Should I be doing something different?
 
caliginousface said:
Yeah I was trying to do the same thing with this Duchess chart and it doesn't work out.

And when you say for the altitude in question, I was assuming a 30 degree C surface temp at SL, putting the the Absolute Ceiling at 8000ish. Because I don't know what altitude the Absolute Ceiling is. Should I be doing something different?
Click to expand...

I offer this to you cautiously. I did it in a hurry, 'cause I'm shutting down for the night.
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View attachment 3504
 
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