Prop over speed after takeoff?
- Thread starter mark
- Start date
hey mark!
the O-435-A in my 14-19 has a controllable prop, but not a constant speed. this basically means that you have a fixed pitch prop that you can adjust in flight. so, if you get 2500 rpm for your take off roll, it's not surprising that it will go to 2700 as you accelerate and the prop "unloads". the only way to deal with this is to either pull the nose up (load the prop) or dial the prop back.
i have found that if i twist the prop control back about 2 turns before takeoff, this gives me approx 2500 by the time i rotate and around 2550-2600 for climbout at 90 mph ias. then on the downwind, i'll dial it back to 2500 and 100 mph for cruise-climb.
the O-435 in various forms is rated up to 3200 rpm continuous. however, the hartzell prop is redlined at 2600 rpm. i am more concerned about overspeeding the propeller than i am the engine. losing a prop blade on full power take off would just completely ruin my day!
hope this helps!
blue skies,
vic & N522A
the O-435-A in my 14-19 has a controllable prop, but not a constant speed. this basically means that you have a fixed pitch prop that you can adjust in flight. so, if you get 2500 rpm for your take off roll, it's not surprising that it will go to 2700 as you accelerate and the prop "unloads". the only way to deal with this is to either pull the nose up (load the prop) or dial the prop back.
i have found that if i twist the prop control back about 2 turns before takeoff, this gives me approx 2500 by the time i rotate and around 2550-2600 for climbout at 90 mph ias. then on the downwind, i'll dial it back to 2500 and 100 mph for cruise-climb.
the O-435 in various forms is rated up to 3200 rpm continuous. however, the hartzell prop is redlined at 2600 rpm. i am more concerned about overspeeding the propeller than i am the engine. losing a prop blade on full power take off would just completely ruin my day!
hope this helps!
blue skies,
vic & N522A
Jonathan Baron
New member
What Vick said, regarding the Hartzell HC 12x20, with the exception of redline which was 2900 on props in some applications when they were new - not that I'd run it that high; you're liable to stretch the oil bladder and ultimately cause it to fail. When learning to fly the airplane I must confess that I did get the RPM that high <blush>, but not intentionally. The airplane actually climbed better when I reduced RPM - probably because I'd yet to discover that my prop was 80 inches rather than the TC specified 78.
Regarding reducing RPM, I was told by my instructor that I should reduce power first, and then pull back the prop to save strain on the engine. But everybody has their idea of what constitutes undue strain and what doesn't so take that FWIW.
Although I don't have my POH in front of me, I recall Vy for the 14-19 as 103mph, subtracting 1mph for each 1000 ft. of altitude.
2550 is book redline for Cruisemasters with the O-435A1. It should pretty much stay that way even with the later, heavy duty prop clamps and a conversion to the O-436A1 rated at 225hp. You can only get the higher horsepower at higher RPM. Thus most of the people who opted for the conversion did so to either prevent lead fouling or for non-standard ops (well...non standard nowadays) such as bush flying or operating out of short fields during hot months.
One fellow very experienced in such ops would employ flaps on take-off and run as high as 2850 at Vx which is just below Vfe. Yes, he got into and out of fields that would create a laundry emergency for most of us. However, he'd done this sort of flying in his 14-19 for 29 years.
Many 14-19s were operated in this manner (my airplane was originally delivered to Alaska for ops there, for example, and the logbook notes it also operated on skis) in the early '50s. Those were very different times, however, and very different pilots.
Today, on contemporary GA airfields, I firmly believe that the book number of 2550 is good and there is no need to depart from it.
It's interesting to know that the airplane can do remarkable things apart from the norm. Heck, it's part of the breed's history. Many of today's pilots regard the old time Bellanca pilots as being close to nuts. I've known several though. They learned to fly when young, they're old men now, thus their very existence proves they were not reckless. Now, if I try to pull the sort of things in my 14-19 that they did, THAT would be reckless :lol:
Jonathan
Regarding reducing RPM, I was told by my instructor that I should reduce power first, and then pull back the prop to save strain on the engine. But everybody has their idea of what constitutes undue strain and what doesn't so take that FWIW.
Although I don't have my POH in front of me, I recall Vy for the 14-19 as 103mph, subtracting 1mph for each 1000 ft. of altitude.
2550 is book redline for Cruisemasters with the O-435A1. It should pretty much stay that way even with the later, heavy duty prop clamps and a conversion to the O-436A1 rated at 225hp. You can only get the higher horsepower at higher RPM. Thus most of the people who opted for the conversion did so to either prevent lead fouling or for non-standard ops (well...non standard nowadays) such as bush flying or operating out of short fields during hot months.
One fellow very experienced in such ops would employ flaps on take-off and run as high as 2850 at Vx which is just below Vfe. Yes, he got into and out of fields that would create a laundry emergency for most of us. However, he'd done this sort of flying in his 14-19 for 29 years.
Many 14-19s were operated in this manner (my airplane was originally delivered to Alaska for ops there, for example, and the logbook notes it also operated on skis) in the early '50s. Those were very different times, however, and very different pilots.
Today, on contemporary GA airfields, I firmly believe that the book number of 2550 is good and there is no need to depart from it.
It's interesting to know that the airplane can do remarkable things apart from the norm. Heck, it's part of the breed's history. Many of today's pilots regard the old time Bellanca pilots as being close to nuts. I've known several though. They learned to fly when young, they're old men now, thus their very existence proves they were not reckless. Now, if I try to pull the sort of things in my 14-19 that they did, THAT would be reckless :lol:
Jonathan
Jonathan Baron
New member
That was a typo on my part, Mark. The engine you have is the O-435A1. The conversion is the A2. You'll have to consult an overhaul shop, plus I'm not sure who can legally change the dataplate on the engine making it a legal A2 conversion.
To the best of my knowledge, the change involves switching to higher compression pistons primarily. You won't get much more out of the engine. As I said, you dare not set the timing to A2 specs in the Bellanca installation due to CHT concerns, and it only produces the full 225hp at 3000rpm.
If you're actually getting the cruise speed and climb rate numbers you quoted in another topic on this forum common sense says don't touch a thing
Jonathan
To the best of my knowledge, the change involves switching to higher compression pistons primarily. You won't get much more out of the engine. As I said, you dare not set the timing to A2 specs in the Bellanca installation due to CHT concerns, and it only produces the full 225hp at 3000rpm.
If you're actually getting the cruise speed and climb rate numbers you quoted in another topic on this forum common sense says don't touch a thing
Jonathan
Jonathan Baron
New member
The RPM/HP graph for the O-435 came with my owners manual - not the PR manual but the CAA approved one. As you probably know, these are not linear. The geared version of the engine, used in Navions and others, produced 260hp at 3200 rpm I believe, though my memory is a bit hazy - the rpm could have been higher on the geared version.
Jonathan
Jonathan
Jonathan Baron
New member
This link should provide all the info you'd want/need, Mark.
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/9e687ca917737e5a8525670e0052fcc6/$FILE/E-228.pdf
Jonathan
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/9e687ca917737e5a8525670e0052fcc6/$FILE/E-228.pdf
Jonathan