Question about Grumman AA1 in regards to density altitude

C

Christianowen71

Filing Flight Plan
Joined
Jan 7, 2024
Messages
5
Display Name
Display name:
Christian owen
Hey y’all, this is my first post here. I’m a new private pilot with only 60 hours. I own a 1978 Grumman AA1C lynx with an upgraded 125hp Lycoming O235 L2C. It’s a fun little airplane with agile handling and a solid cruise speed for being a 2 seater. The only real downside with this plane is its climb performance and ground roll on takeoff. My concern moving forward is when i start pushing into new airports with a higher density altitude. Of course going by the POH and calculating ground roll and climb performance pertaining to the DA is necessary, but does anyone have any advice or experience in high DA airports in a airplane that doesn’t perform all too well in those conditions ? Would love to hear your feedback :)
 
I used to own that same plane, fun to fly but did not climb well, on a hot day it was even worse, fly it light and re-pitch the prop to a climb prop

I was based at an airport long ago that had all the little Grummans for trainers, there was a power line right at the North end of the runway, saw a few go under the wires on hot days, and the airport was at 700ish MSL,

If you fly out of high DA airports enjoy the scenery at 100 feet for a few miles before it decides to climb

Just be very careful how loaded you are on hot days and how long the runway is and have fun, kind of noisy with canopy slightly open in flight, only other thing I remember was that on a bumpy hot day it was not fun
 
The runway length question kinda answers itself by you computing the DA & doing the look-up in the poh (at first add 20% to account for technique & uncertain prop pitch, then reduce with experience).

I’d be more concerned about the obstacles off of the end of the RW. And even more concerned with rising terrain around the airport. In a 150 I’ve stayed in the pattern for 3 or 4 turns around the field in order to climb away from rising terrain while not tangling with it directly. The last thing you want to do is take the terrain head-on by trusting you’ll out climb it.

Departing at the butt-crack of dawn & in the pink of the evening are your friends.
 
I had an original AA1 with the “hot wing” and the C2C engine. Its climb rate wasn’t all that different from any other 100 hp 2 seater. The difference was you were doing 20mph more across the ground at the same climb rate which makes it feel worse than it really is. I will say I didn’t trust the numbers the POH gave and determining the height of the obstacle is almost impossible. You have to be comfortable with the difference of clearing it versus clearing it with a buffer. I did all my instructing in one with another typical adult male so we stuck to your typical regional style airports with 4k+ runways. I did take a buddy to a flyin at a 6k grass runway in July and remember thinking the ground was rising as fast as we were. We cleared the trees but it took several miles to get a comfortable margin between us and the terrain. As you gain experience you will gain confidence and know your limitations.
 
Where are you located and where do you plan to fly with high DA?
 
Respect DA. Flying w DA really requires “fly the airplane” skill- all the numbers are necessary for planning, but you will need a bit more than them once moving. I flew a Cessna 140 from Michigan to J Creek Idaho twice. Fly thy airspeed- fly thy airspeed- fly thy airspeed. May require vastly different power settings and sight pic. Be light and set your alarm for flight at dawn…

I had to turn around and land once as my bird was flying but not well, there was no way I was flying for a few hours over rough terrain in a plane that just didn’t want to be flying and she wasn’t flying well. The 1947 handbook was a handbook at best for guidance. All turned out fine but was closer to the limit than I’d go again… she needed a fair amount of power to the numbers that was very abnormal to need that. Fly the plane, fly the airspeed, stay light Leave early…
 
I echo @murphey’s comment. Where are you talking about and what kind of routes. I’d add, what type of experience.

I‘ve flown Cessna 172s from the Colorado Front Range into Leadville (9933 MSL) but wouldn’t consider it an airplane of choice for that type of flying on a general basis. “Down” on the high planes, perhaps a different story.
 
rhkennerly said:
The runway length question kinda answers itself by you computing the DA & doing the look-up in the poh (at first add 20% to account for technique & uncertain prop pitch, then reduce with experience).

I’d be more concerned about the obstacles off of the end of the RW. And even more concerned with rising terrain around the airport. In a 150 I’ve stayed in the pattern for 3 or 4 turns around the field in order to climb away from rising terrain while not tangling with it directly. The last thing you want to do is take the terrain head-on by trusting you’ll out climb it.

Departing at the butt-crack of dawn & in the pink of the evening are your friends.
Click to expand...
This was kinda what i was thinking. I live in SoCal and we have a local high density altitude airport Big Bear near us. the problem wouldn’t necessarily be getting off the runway more so climbing out of the valley that it sits in. the allowable terrain to climb is limited whereas a airport like Sedona may sit at the same DA as big bear but there’s plenty space to climb. Thanks for your reply
 
Huckster79 said:
Respect DA. Flying w DA really requires “fly the airplane” skill- all the numbers are necessary for planning, but you will need a bit more than them once moving. I flew a Cessna 140 from Michigan to J Creek Idaho twice. Fly thy airspeed- fly thy airspeed- fly thy airspeed. May require vastly different power settings and sight pic. Be light and set your alarm for flight at dawn…

I had to turn around and land once as my bird was flying but not well, there was no way I was flying for a few hours over rough terrain in a plane that just didn’t want to be flying and she wasn’t flying well. The 1947 handbook was a handbook at best for guidance. All turned out fine but was closer to the limit than I’d go again… she needed a fair amount of power to the numbers that was very abnormal to need that. Fly the plane, fly the airspeed, stay light Leave early…
Click to expand...
Thanks for the Advice. Yeah it seems theres so many factors to flying high DA then what the POH says. I’ll keep in mind the whole fly early leave at dawn advice :)
 
Grum.Man said:
I had an original AA1 with the “hot wing” and the C2C engine. Its climb rate wasn’t all that different from any other 100 hp 2 seater. The difference was you were doing 20mph more across the ground at the same climb rate which makes it feel worse than it really is. I will say I didn’t trust the numbers the POH gave and determining the height of the obstacle is almost impossible. You have to be comfortable with the difference of clearing it versus clearing it with a buffer. I did all my instructing in one with another typical adult male so we stuck to your typical regional style airports with 4k+ runways. I did take a buddy to a flyin at a 6k grass runway in July and remember thinking the ground was rising as fast as we were. We cleared the trees but it took several miles to get a comfortable margin between us and the terrain. As you gain experience you will gain confidence and know your limitations.
Click to expand...
That’s a good point. My climb speed is significantly greater than other similar low HP 2 seaters. I’ll be sure to keep in mind nearby terrain.
 
Christianowen71 said:
Thanks for the Advice. Yeah it seems theres so many factors to flying high DA then what the POH says. I’ll keep in mind the whole fly early leave at dawn advice :)
Click to expand...

Oh and if it’s truly high DA- gotta lean for take off. Makes a big difference. But it’ll make a better pilot out of you!

It’s one of the reasons I cringe when I see folks too mechanical in their approach to flying. 1726rpm at this point in pattern then 1475rpm at this point in pattern, etc (hyperbole intended)… that may work fine at home field most days… if ya fly that way in DA one could get in trouble fast.

But experiences like dealing with DA will make ya a better pilot… when things get complicated go back to the bare bone basics- fly the thing.

One tip I found helpful I’ve not seen a lot of places is if runway allows it I would look to get airborn asap but then hold like a soft field and let her gain some speed in ground effect before attempting to actually climb. This improved my climb performance significantly it seemed… no numbers to go off of, but by feel I certainly noticed and held to the practice.
 
Go find higher airport.
Go find CFI experienced in high altitude airport operations
Go learn.

Both Colorado Pilots Assoc and New Mexico Pilots Assoc have programs to teach high altitude airport operations 2-3 times a year.

Go find Utah or AZ CFI and learn same.
 
Owned an AA-1A for 4 years with the stock O-235-C2C. Nice little plane. If you fly solo and light you have more options. I have flown it loaded to gross (2 aboard a a little luggage) on a hot day at low elevation and it is pretty sluggish with climb. The POH is good guidance, just consider it the absolute maximum performance and give yourself plenty of margin, because you won't get the book numbers for runway use and initial climb. It's not a good choice for high DA operations.
 
You must log in or register to reply here.
Back
Top