Syncing props on the takeoff roll. Yes or no?

aloft said:
True, but full-rated power for takeoff in a turbo is generally overkill. If a normally-aspirated 182 can take off with only 24", so can a turbo'ed one.
Click to expand...

Agreed, and that's why many engines are simply turbonormalized. However, there are many aircraft currently flying that don't have a non-turbo variant. My aircraft develops 39" MP at takeoff power, and I'll tell you that it's not overkill. It's what the engine is designed to produce, and that's what every takeoff performance chart in the book is predicated on using.
 
aloft said:
True, but full-rated power for takeoff in a turbo is generally overkill. If a normally-aspirated 182 can take off with only 24", so can a turbo'ed one.
Click to expand...

If you have takeoff performance data for flex takeoffs, and the performance numbers meet the requirements that you face in regards to runway length, temp, altitude, etc., then by all means, takeoff using the flex numbers.

But if you don't, then don't make up your own procedures "because it looks ok." TLAR can get you in a lot of trouble when you start making up your own procedures, and if you bend metal one day, you will find yourself with little defense from the FAA, the insurance company, and anybody else that you injure in your quest to do things your own way.

If the procedure exists, follow it within the bounds of its limitations, but don't say simply "Well this is probably overkill, let's pull the power back fort his takeoff" when the book doesn't tell you to do so.
 
aloft said:
True, but full-rated power for takeoff in a turbo is generally overkill. If a normally-aspirated 182 can take off with only 24", so can a turbo'ed one.
Click to expand...

Because they are 2 different engines: 230hp vs 235hp. One is normally aspirated and the other is turbo-normalized. That is why the Normal Ops green arc tops at 28". In the NA 182T you can get over 30" on T/O whereas you you will get 32" in a T182T. IF something goes wrong, I'd bet that the PIC will become intimately familiar with 91.13.
 
jtrain609 said:
If you have takeoff performance data for flex takeoffs, and the performance numbers meet the requirements that you face in regards to runway length, temp, altitude, etc., then by all means, takeoff using the flex numbers.

But if you don't, then don't make up your own procedures "because it looks ok." TLAR can get you in a lot of trouble when you start making up your own procedures, and if you bend metal one day, you will find yourself with little defense from the FAA, the insurance company, and anybody else that you injure in your quest to do things your own way.

If the procedure exists, follow it within the bounds of its limitations, but don't say simply "Well this is probably overkill, let's pull the power back fort his takeoff" when the book doesn't tell you to do so.
Click to expand...

This is all about knowing your airplane. All the test data in the world doesn't mean a damn thing if you don't know how your airplane is going to react to a given set of circumstances. If Joe Schmoe has gone out to a sufficiently long enough field and tried reduced power setting takeoffs with a good abort point picked out, what's the big deal? Now he knows that for a given set of conditions the airplane will perform in a given manor.

You realize that all that experimental data basically went out the window as soon as the thing started flying a line day in and day out. It's a good baseline for the actual performance, but its not something that's gospel or set in stone. The actual engineering data for a 40 year old airplane or even a 10 year old airplane doesn't match the actual performance, not even in the least.
 
JTrain - Why do you feel that you need the book performance numbers? Where are you coming from?
 
I'm going to side with jtrain on this one, at least from my perspective. If there's a random Alaska-pilot reason to use a reduced power takeoff in a piston, well, I'll defer to you guys on that. ;)

In my type of flying, the book numbers for takeoff and landing are important. It's a 30 year old airplane, but I've found that the numbers are still rather accurate. I'm operating off of a 4100' runway on most days, which is starting to get a bit tight for takeoff when it's warm out. I really need to go by the book numbers on takeoff, do static power-ups for takeoff, and look through the accel-stop and accel-go numbers to see if it's even legal or safe. Sometimes that 4100' runway needs to be waived with a heavy load, but I wouldn't know that unless I pulled the book out and actually checked. Sure, the airplane at MTOW would get off the ground, but if I popped one at 95-100 knots on the runway, I'd overrun and bend metal (Twin Cessna brakes are terrible).

C172 on a 10,000 runway during a training flight? Sure, do what you want...you'll probably be fine. But do be prepared to defend yourself if something happens. If you're operating a flight for-hire, however, going by book performance numbers is important.
 
Douglas said:
JTrain - Why do you feel that you need the book performance numbers? Where are you coming from?
Click to expand...

Again, well played :rawk:

The FAA is going to be MEETING folks at the court house if they follow through with unauthorized, untested and unsound procedures. If they want to do that, it's their choice, but to trump up these ideas as good does a huge disservice to any impressionable pilots reading them.
 
jtrain609 said:
Again, well played :rawk:

The FAA is going to be MEETING folks at the court house if they follow through with unauthorized, untested and unsound procedures. If they want to do that, it's their choice, but to trump up these ideas as good does a huge disservice to any impressionable pilots reading them.
Click to expand...

I also think a disservice is rendered when you speak in absolutes of "never", when it is obviously that "never" is your opinion and not the FAAs, yet you invoke them.

There are too many situations and types of aircraft in aviation is to be a hard-liner on just about anything. Your experiences are only valid for yourself, you know-what-I-mean-mano? :)
 
Douglas said:
I also think a disservice is rendered when you speak in absolutes of "never", when it is obviously that "never" is your opinion and not the FAAs, yet you invoke them.

There are too many situations and types of aircraft in aviation is to be a hard-liner on just about anything. Your experiences are only valid for yourself, you know-what-I-mean-mano? :)
Click to expand...

Beyond the training environment and simulating high-DA operations, is there any reason to do this type of takeoff in a piston airplane?
 
If there was some big benefit to de-rated takeoffs (piston), why wouldn't engine or aircraft manufacturer's be using it? The engines still get overhauled at set times anyways..I'll follow the manufacturer's suggestions thanks.
 
Baronman said:
If there was some big benefit to de-rated takeoffs (piston), why wouldn't engine or aircraft manufacturer's be using it? The engines still get overhauled at set times anyways..I'll follow the manufacturer's suggestions thanks.
Click to expand...

Exactly, and unlike a jet aircraft where derated takeoffs can save wear, doing takeoffs with less than full power in a piston can actually cause more wear.

http://www.avweb.com/news/pelican/182045-1.html

Scroll down to "Partial-Power Takeoffs" and his talk about Power Enrichment Valves.
 
dasleben said:
Beyond the training environment and simulating high-DA operations, is there any reason to do this type of takeoff in a piston airplane?
Click to expand...

Other than training and just having fun, I can't think of anything.

It is the "never" that I take objection too. If somebody were to say, "I will never..." I am cool with that.
 
Douglas said:
I also think a disservice is rendered when you speak in absolutes of "never", when it is obviously that "never" is your opinion and not the FAAs, yet you invoke them.

There are too many situations and types of aircraft in aviation is to be a hard-liner on just about anything. Your experiences are only valid for yourself, you know-what-I-mean-mano? :)
Click to expand...

I think a disservice is rendered when we coddle people into believing that each and every one of their opinions is a treasured special snowflake, and that it's ok to do things completely wrong as long as you feel good about it.

There are right ways and wrong ways to do things. Now, within the right way and wrong way to do things, there are variances in technique and procedure, but when these differences exist, then there are multiple procedures on them. If that's the case, then we should all obviously feel free to debate which technique is preferable.

This is not one of those situations. Want to talk about reasons for or against using flex takeoffs in an aircraft with that procedure, then that's great! Small piston engine aircraft don't have those procedures, and if they do then they don't apply to this conversation.
 
My half thought out advice for the day: Never assume aaaaaaanything in an airplane.
 
jtrain609 said:
I think a disservice is rendered when we coddle people into believing that each and every one of their opinions is a treasured special snowflake, and that it's ok to do things completely wrong as long as you feel good about it.

There are right ways and wrong ways to do things. Now, within the right way and wrong way to do things, there are variances in technique and procedure, but when these differences exist, then there are multiple procedures on them. If that's the case, then we should all obviously feel free to debate which technique is preferable.

This is not one of those situations. Want to talk about reasons for or against using flex takeoffs in an aircraft with that procedure, then that's great! Small piston engine aircraft don't have those procedures, and if they do then they don't apply to this conversation.
Click to expand...

The trouble of opinions is that nobody is of the opinion that somebody else should have one, dare it rub against theirs.
 
You must log in or register to reply here.
Back
Top