Hobbs vs. Tach

[BizPilot]

I did a search for this topic already, so don't jump all over me. I still couldn't find a good answer.

I am renting an aircraft from an FBO that charges by TACH time. I want to get the most "bang" for my buck. What is the best way to run? (I understand the whole "in the pattern" theory, but I need an answer for long-haul flights)

Do I want to pull the power back to, lets say, 55% power and run a slow Tach?

Or do I want "balls to the wall" and run it at red line?

What is going to give me the best return on my rental dollar?

Thanks!

 

[sky37d]

Tach time is simply that, the time the engine is running, at some predetermined RPM. Hobbs time, typically, happens when the master is on. So, it doesn't matter how lean, fast, etc you run the engine, (unless it is just at idle), it is still going to register time running.
If you are paying by the hour, and you just want to stay in the pattern, it doesn't much matter. If you are doing a cross country, go flat out, below redline of course, make sure it is not to lean.

 

[PacoPollo]

Some freighters,fbo's use Hobbs time on the airplanes.There is usually a switch below the panel that turns the damn thing off.

 

[Flysher]

depending on the plane i think the tach runs off engine speed, so at idle it will turn over less than at full throttle.

Hobbs meter on Cessnas is tied to oil pressure line, Seminoles i flew were tied to the master.

check the POH for the plane and find out i guess.

 

[avbug]

What's going to give you the best return for your rental dollar really depends on what you hope to accomplish with that rental dollar.

If you're renting to actually accomplish something, like go somewhere, then powering back to a minimum power setting won't help you out much.

If you're trying to stay aloft as long as you can and save money, with no particular aim, then yes, flying at a reduced RPM setting will fly you the longest for the slowest turnover on the tach odometer.

If you're just in it to build time, then forget paying for the aircraft and write it in your logbook. If you're in it to build some experience, then go fly maneuvers, approaches, and whatever else you need to do to build your proficiency, and pay for whatever the tach gives you.

A company charging by tach time is giving you a good deal.

Electronic hour meters may be activated in any number of ways, from oil pressure switches to landing gear position switches, air presure switches (based on airspeed), squat switches, electrical direct when the battery master is on, etc.

The tach turns slower at lower RPM's, and the rate at which it records time is slower, too.

 

[FlyingFisherman]

There are several levels of flying style I use based on who's paying the bills.

Private aircraft on business trip. Daily Rate + hourly rate = reduced power settings for passenger comfort and increased fuel efficiency.

Rented aircraft in which I'm the instructor. - "You don't need to fly at 2500rpm in a 172 while in cruise. 2300 is a much better power setting, it's quieter and easier on the engine in the long run."

Rented aircraft in which I am alone. - "Balls to the wall I'm paying for this thing!"

It is absolutely possible to get 165kts TAS out of a 200hp Mooney M20J. You CAN get them slowed down from 160 to 81kts between the outer and middle markers using nothing but the landing gear, prop and a healthy dose of sideslip to do so. They also land in <800' if you want them to and don't mind using someone elses brakes.



If you're trying to build time then renting an airplane while paying for the tach is the best deal going. Log the hobbs and then pay the tach...that's a great deal! Not many places do that and if it's your deal...you've got a good one.

 

[A Squared]

Rented aircraft in which I am alone. - "Balls to the wall I'm paying for this thing!"

It is absolutely possible to get 165kts TAS out of a 200hp Mooney M20J. You CAN get them slowed down from 160 to 81kts between the outer and middle markers using nothing but the landing gear, prop and a healthy dose of sideslip to do so. They also land in <800' if you want them to and don't mind using someone elses brakes.

So if it's somone else's airplane, you don't have any qualms about abusing it. Nice.

 

[Flysher]

Rented aircraft in which I'm the instructor. - "You don't need to fly at 2500rpm in a 172 while in cruise. 2300 is a much better power setting, it's quieter and easier on the engine in the long run."

LOL I'm guilty of that one.

In all seriousness though it does hurt your ears if you goin a long distance.

 

[Mr Wu]

I did a search for this topic already, so don't jump all over me. I still couldn't find a good answer.

I am renting an aircraft from an FBO that charges by TACH time. I want to get the most "bang" for my buck. What is the best way to run? (I understand the whole "in the pattern" theory, but I need an answer for long-haul flights)

Do I want to pull the power back to, lets say, 55% power and run a slow Tach?

Or do I want "balls to the wall" and run it at red line?

What is going to give me the best return on my rental dollar?

Thanks!

Grab the POH and load the profiles into DUATS for the different power settings. Then all you have to do is have it calculate flight time for the different settings and apply rental cost to your answer. Most of these tachs are set for 100% or something close to that. Just use 55% of rental fee for 55% power, etc. Should get you in the ballpark.

 

[avbug]

Rented aircraft in which I am alone. - "Balls to the wall I'm paying for this thing!"

It is absolutely possible to get 165kts TAS out of a 200hp Mooney M20J. You CAN get them slowed down from 160 to 81kts between the outer and middle markers using nothing but the landing gear, prop and a healthy dose of sideslip to do so. They also land in <800' if you want them to and don't mind using someone elses brakes.

As a matter of honor, you should always return a man's equipment in better shape than you found it, w(h)eather you're borrowing it, or renting it. As a practical matter of airmanship, you should always take ownership of an aircraft when you fly it, and treat it accordingly.

Never abuse an airplane. Treat it as though your life depends upon it.

Because it does.

The cracks caused in the vertical stab attach brackets from sideslipping at high speeds may not affect you, but may affect the pilot days or years later when the aircraft fails. The brakes you burn up because you're "not paying for them" will raise the cost of the aircraft and everyone will pay..or they might just fail from repeated overheating and cracking, and hurt someone else. What do you care? You're not paying for it, right?

What you're describing isn't something to brag about. It's a character flaw, and unless corrected, ought to be a source of embarassment to you.