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taxi speed / engine rpm

lucaperazzolli

lucaperazzolli

Well Known Member
Fellows here @ Lycoming official distributor did a meeting where they sad don't run your engine under 1000 rpm due to poor oil pressure inside the system

Well, I try to taxi my 8 @ 1000 rpm but ... the things happens so quickly and my brakes don't like that.

Could you share with me your idea about taxi rpm speed without destroying a new engine / or brakes ?
 
i don't think you can do it unless you have a c/s. I run my at 1000 with no issue. I never touch the brakes and speed is about 12kts ground.
 
I've always been taught, and try to practice, that taxi should be no faster than a brisk walk.
12kts is 13.8 mph.
I can't walk that fast!
 
Mel said:
I've always been taught, and try to practice, that taxi should be no faster than a brisk walk.
12kts is 13.8 mph.
I can't walk that fast!
Click to expand...

Mel is technically right...

However, that reference was written because a Spad or Camel didn't have brakes and the "wing walkers" would hold the handles at each end of the wing during taxi. When a right turn was needed, the right walker would dig his heals in and the left walker would start to "Briskly walk"...

ahhh, gotta love disc brakes!
 
Mel said:
I've always been taught, and try to practice, that taxi should be no faster than a brisk walk.
12kts is 13.8 mph.
I can't walk that fast!
Click to expand...

That's what I was taught too, but it was on small non-towered airports.

If I did that at Tucson (TUS) it could be a 30+ minute taxi to the end of the main 11,000 ft. runway....:eek:
 
950 - 1000 rpm

I taxi at 950 - 1000 rpm.

My gear starts to vibrate at 20 mph, so I tap my toe brakes and use my GPS to keep my speed at about 16 - 17 mph. I've tried idling my engine down to 900, but it shakes too much.
 
Mel said:
I've always been taught, and try to practice, that taxi should be no faster than a brisk walk.
12kts is 13.8 mph.
I can't walk that fast!
Click to expand...

Now now, what if I tell you I'm one of the slowest taxi plane at my airport. Yup, just the other day I swear a cessna was taxi at about 30, well I bet if he pulled back on the yoke he would have done a taxi way lift off, this guy was really goin.

I will also add that I do the 12kts when on the parrallel taxiway and about 5 when in the hangar areas, but still with the c/s there is no problems going slower just hit a little brakes and it's slows right down and to speed up I have to add a little power to do it. no issues for me.

Yes I use the gps and my front gear vibrates at 20 also.
 
Last edited:
I agree with Mel and Gil.

When I taxi from the fuel pit to my hangar, I need 1,700 RPM to get the airplane moving and about 1,500 RPM to keep moving. Yes it is up hill.

On level, my constant speed prop O-320 is about 1,200 RPM. Speed is about 12 Kts. No problem idling at 700 to 800 RPM but that is too slow to get the airplane to move unless it is facing down hill.
 
My fixed pitch O-320 powered four will smoothly idle down to about 850 or 900 (if the plugs are clean, and they always are...) The Landoll ring is responsible for the last 100-150 of that number... I taxi at about 5mph, let it accelerate up to about 15 then slow it down again, so as not to ride the brakes. 5 or 6 mph is slow enough that it takes about 15 seconds or so to accelerate back up to the point of needing brakes again.
When your stopped however, push the power up to the first "smooth" RPM. Usually 1000 to 1100 rpm. Lean it way out, and call that your idle with the brakes set. It's much better for the engine.
Good luck ;-)

Dennis
 
My O-320 with 9.5:1 C/R will idle smoothly at 700 rpm. Sounds like some of you guys need to look into something.
Catto 3-blade and 2 magnetos.
 
Thanks, but nobody concerned about the minimum 'safe' engine rpm.

My brainstorming is:

case A) if I taxi @ idle (650 rpm) I stay into the right walking speed BUT is my engine suffering poor oil pressure due to low engine rpm ?

case B) if I taxi @ 1000 rpm (right for engine) I run too quick so I need to apply brakes too many time but the engine would be OK due to 1000 rpm.

BTW: I've Catto 3 blds/O-360-A1A/idle @ 650 rpm
 
"Safe" engine RPM

The easiest way to make sure that your engine is getting enough oil is to watch the Oil Pressure gauge! As long as your oil pressure is within Lycoming's limits, then you can be assured that you're getting enough oil throughout the engine.

I don't have the Lycoming manual in front of me. I think that around 35 psi is the low oil pressure limit. My engine idles at 650 rpm at 52 psi. Cruises at 72 psi.
 
DakotaHawk said:
The easiest way to make sure that your engine is getting enough oil is to watch the Oil Pressure gauge! As long as your oil pressure is within Lycoming's limits, then you can be assured that you're getting enough oil throughout the engine.

I don't have the Lycoming manual in front of me. I think that around 35 psi is the low oil pressure limit. My engine idles at 650 rpm at 52 psi. Cruises at 72 psi.
Click to expand...

My O-360 manual has the minimum oil pressure as 25 psi at idle.

Lycoming says the idle speed is set by the airframe manufacturer - as examples my Tiger (O-360A carb - FP prop) is 500-650 rpm. A Cheetah (O-320E carb - FP prop) is 600-650 rpm.
 
On the recommendation of a couple of my local "old timers", of which I am quickly becoming one, I set my oil pressure towards the high side.

In checking my Dynon log files, I'm running 84 PSI at 2600 RPM, 65 PSI at 1000 RPM, and down to 58-60 PSI at 667 to 700 RPM. (I need to turn my idle down a little more. Ya gotta love EI for allowing low idle speeds.)
 
Low Idle

If the oil pressure is within limits, and the engine is running smooth, idle as low as you want. Just make sure you lean it out or you'll fowl the plugs.

Float planes often have the idle set as low as possible so your not racing towards the dock too fast. I know one that would quit running if you pulled the throttle completely closed. It was a IO-520, but same logic applies. On the radial stuff, you can almost count the blades when they idle really slow.
 
RV6_flyer said:
I agree with Mel and Gil.

When I taxi from the fuel pit to my hangar, I need 1,700 RPM to get the airplane moving and about 1,500 RPM to keep moving. Yes it is up hill.

On level, my constant speed prop O-320 is about 1,200 RPM. Speed is about 12 Kts. No problem idling at 700 to 800 RPM but that is too slow to get the airplane to move unless it is facing down hill.
Click to expand...

Of course the difference in props makes a huge difference in taxi RPM. When I switched from FP to CS I was amazed at how much more throttle it took for the CS to move the airplane. Now I'm used to it and don't think about it.

My oil pressure is 80-90 lbs no matter what rpm my engine is at so I don't think low rpm taxi is going to hurt the engine.
 
I've had it explained to me that the cam receives lube from oil slung from the crank. With cold thick oil it needs about 1000 rpm to effectively get it where it needs to be. Once the oil warms to operating temp it doesn't need as much rpm to sling to the cam. Correct me if I'm mistaken.
 
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