Grumman AA1 at high density altitude

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PilotChango

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PilotChango
I'm shopping around for a first airplane and have been considering the AA1 models.

I'm instrument rated with about 275 hours TT. My mission is building time on long all-weekend cross country trips, sometimes punching through clouds as needed. I live near Denver and love flying all over, including to Montana, Texas, and Michigan. Sometimes I take my CFI on these trips for company. I weigh 180, my CFI weighs 150. So, crew + passengers total anywhere from 180 to 330. Baggage is pretty light: flight bags, sleeping bags, a pillow, some oreos, etc. Maybe 30 pounds total.

The AA1 is appealing because it is economical, fast (for its "class"), sporty, good looking, and benefits from high wing loading, which is helpful in gusty/bumpy Colorado. But, I think, for my mission, it might not have enough useful load to allow any reasonable range on cross country trips. Plus, I'm concerned about its climb performance here, where density altitude in the summer can sometimes reach 8,500 feet or more.

So, two questions:

1) Does anybody have any experience flying an AA1 in Colorado or other places with high density altitude?
2) Can anybody convince me that the AA1 could actually meet my mission objectives with such a low useful load? I'm open to other suggestions within the same price range.

Thank you!
 
Isn't usable fuel only like 24 gallons?

I think a Cherokee 140 would be a better option.
 
Racerx said:
Isn't usable fuel only like 24 gallons?

I think a Cherokee 140 would be a better option.
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22 gallons usable, I believe.

A Cherokee 140 is almost certainly a more rational choice for me, as are a number of other aircraft. That's the null position. I'm really just curious if anybody can make the argument that the AA1 is a good option for my mission.
 
I mean, it's going to be about the same as anything else with an O235. It's going to be pretty limited in the summertime at those altitudes and useful load. Personally, I don't think it will be a good airplane at all for your mission.
 
RyanB said:
I mean, it's going to be about the same as anything else with an O235. It's going to be pretty limited in the summertime at those altitudes and useful load. Personally, I don't think it will be a good airplane at all for your mission.
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I'd be inclined to agree. I live in Las Vegas and we have some relatively high DA's and of course blisteringly hot summers. When I was going through CIrrus transition training here any flying new SR20's, I thought their performance was barely adequate in the summer. I can't imagine an AA1 or PA28-140 being adequate for the Denver environment. I would recommend at a minimum a Cherokee 180. I have a Cherokee 235 performs beautifully in high heat and high DA ( 3 blade prop helps) but as I said, at least a Cherokee 180 or similar.
 
I instructed in the early slick-wing AA-1 Yankees when they first came out, and loved flying them. But home base was a sea-level airport (LGB) and I never really had the occasion to test the high-altitude capability of the airplane.

The AA-1 owner's manual claims a service ceiling of 11,350'. Looking at that stubby little wing, that's probably optimistic -- if not outright prevarication. Figure 6 to 6.5 gph at cruise power, and with a mere 22-gallon usable fuel capacity, you'll be sweating IFR reserves not long after [or if] you manage to climb to altitude. Too bad; the airplane is a delight to fly, and not a bad IFR platform.

There are some 150 hp AA-1 conversions out there, but nothing can be done about those tiny fuel tanks, which are woefully inadequate for 150 hp. Useful load is worse, too.

The Cherokee 140 (150 hp O-320) shines with its humongous 50-gallon fuel capacity, but it is no homesick angel above eight or nine thousand feet DA, either. Stubby, low-aspect-ratio wings are the culprit again, as the longer-winged Warrior does much better with the same engine and even more size and weight. The Baby Beeches aren't much better, if at all, than the Cherokee 140.

The Cessna 152, with a 110-hp O-235, claims a service ceiling of 14,700'. There is probably some wishful thinking there too, but the 152's longer wings clearly do better than the others up high. Alas, it is slow, and except for the few built with optional "Patroller" tanks, fuel capacity is about the same as the AA-1.

A 150 hp Citabria will scamper right on up there, and you can do some aerobatics when you get there. (Bellanca quoted service ceiling of 17,000' on the 7GCAA and 7GCBC in the '70s; American Champion says 15,000' on the new ones with higher gross weight and ten more horsepower.) And most of them hold at least 35 gallons, though useful load is limited. But they are VFR airplanes, most with tiny panels and minimal equipment. Most are not certified for IFR, regardless of installed equipment.

I agree with the comments by others above -- a 150 hp four-seater (used as a two-seater) would be my absolute rock-bottom minimum, with 180+ hp preferred for any kind of serious transportation.
 
Thank you, Nick. I've flown Archers and Warriors in Denver a number of times on hot summer days. Both performed fine, but I certainly wouldn't say anything less powerful would be unsafe. I've also flown 152s loaded to max gross in the summer time in Denver and had no concerns climbing out of ground effect, even if it was at a sleepy 300 fpm.

Ryan, the 152s I've flown out of Denver were powered by O-235s. So, I don't think the powerplant is the whole story. The 152 has lower wing loading, allowing it to convert a greater share of that limited thrust into lift. The AA1's limitation seems to be its high wing loading and inability to convert as much thrust into lift on the same powerplant. It's climb-out angle will necessarily be significantly shallower than that of a 152, all else held equal.

Again, to reiterate, I am already convinced the AA1 is not a good option. The challenge here is to see if anybody can make a plausible argument to the contrary.
 
I owned one of those 150hp Yankees in Georgia, Southern California and Las Vegas. Even with 150hp, I noticed when it was hot.

I didn't sell it for DA performance, I sold it because of limited useful load (and life circumstances). With the extended range tanks (32gal total) full, it only had about 300lbs left (and I weighed 260 at the time of sale). The laminar flow wing is sensitive to being overloaded, especially at high density altitudes but if you keep it in W&B, with the 150hp, it was still a performer.

I have never flown one with the stock engine, but when hot and high my takeoff rolls extended. So check the POH against your planned destinations and home airport.
 
PilotChango said:
I'm shopping around for a first airplane and have been considering the AA1 models.

I'm instrument rated with about 275 hours TT. My mission is building time on long all-weekend cross country trips, sometimes punching through clouds as needed. I live near Denver and love flying all over, including to Montana, Texas, and Michigan. Sometimes I take my CFI on these trips for company. I weigh 180, my CFI weighs 150. So, crew + passengers total anywhere from 180 to 330. Baggage is pretty light: flight bags, sleeping bags, a pillow, some oreos, etc. Maybe 30 pounds total.

The AA1 is appealing because it is economical, fast (for its "class"), sporty, good looking, and benefits from high wing loading, which is helpful in gusty/bumpy Colorado. But, I think, for my mission, it might not have enough useful load to allow any reasonable range on cross country trips. Plus, I'm concerned about its climb performance here, where density altitude in the summer can sometimes reach 8,500 feet or more.

So, two questions:

1) Does anybody have any experience flying an AA1 in Colorado or other places with high density altitude?
2) Can anybody convince me that the AA1 could actually meet my mission objectives with such a low useful load? I'm open to other suggestions within the same price range.

Thank you!
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Density altitude 9000 …. on the ground….you really need a 180hp.
 
I did a good bit of flying an AA-1B in Texas. I did my Private in an AA-5B.

Fun for knocking around, but the fuel capacity really limits you, especially for IFR.

I remember on flight from KDRT to KCRP. Two of use, probably 350. Overnight gear. We took off and were circling to climb enough to be cleared across Laughlin AFB. Finally the controller got tired of watching us circle, so cleared us any. It was a Saturday and no flying activity at KDLF. :D

Most Grumman came with cruise props for the speed. A climb prop will help. A 150 HP conversion would help a lot, but even higher fuel flow.

There are a couple of aux tank STCs available.
 
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If solo, you could probably make it work. In cold wx, you could probably make it work. That’s probably too many probablies to be comfortable with.

I’m in Salt Lake and fly an AA5B, along with a couple of other planes. The 150 will barely climb with two people on a summer day. I did fly it solo with camping gear to an airport at 7500’ but the climb out was painful. For what you are wanting I would suggest looking at stuff with more HP for safety margins. The AA1B’s bigger brother is a sweet ride if you can find one.
 
I believe part of the aa1 O320 STC is required aux tanks. I’ve read those climb excellent and then pull it back for cruise and can still get good economy and speed. I’ve lusted after AA1 as well but prob would only consider a modified one as I’m on the heavy side.
 
There are a few Cheetahs at Aspen at Centennial. Maybe inquire with the instructors there and get their opinion. Better yet, go fly them and see for yourself?
 
I flew a AA1 from Florida to New Hampshire years ago for a client. If I with two of us, we had to share a toothbrush because packing a second one would put us over weight...

I had a Grumman AA5 traveler. It has the similar wing as the AA1. It's for sale at almost the same price point as some AA1's. I would be looking in that direction.
 
PilotChango said:
Thank you, Nick. I've flown Archers and Warriors in Denver a number of times on hot summer days. Both performed fine, but I certainly wouldn't say anything less powerful would be unsafe. I've also flown 152s loaded to max gross in the summer time in Denver and had no concerns climbing out of ground effect, even if it was at a sleepy 300 fpm.

Ryan, the 152s I've flown out of Denver were powered by O-235s. So, I don't think the powerplant is the whole story. The 152 has lower wing loading, allowing it to convert a greater share of that limited thrust into lift. The AA1's limitation seems to be its high wing loading and inability to convert as much thrust into lift on the same powerplant. It's climb-out angle will necessarily be significantly shallower than that of a 152, all else held equal.

Again, to reiterate, I am already convinced the AA1 is not a good option. The challenge here is to see if anybody can make a plausible argument to the contrary.
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A PA28-140 at 6000 ft and 80°- 90°F is only going to climb 2-300 fpm with much weight.
 
If you want the best chance of getting an authoritative answer, best to ask on the Grumman Gang list serv. You can sign up and access it at: http://grumman.net/. There are multiple people on the GG that have experience with AA1X operation out of high altitude airports.

There are some nuances that have a big impact on the power/useful load/range combination. I don't know the details, but, for example, IIRC the AA1C model offers a material increase in max gross weight over the earlier models. It is almost certainly going to need the 150 hp upgrade for climb performance at high altitude, but as an earlier poster mentioned, throttling back to "stock" speeds will reduce fuel flow to "stock" rates. It will still be going faster than anything else in its class. The A thru C models do not have the laminar flow wing that came with the original AA1.
 
I learned in AA1 in the southeast. With two skinny young men aboard, we'd see about 500 fpm on a summer day while in the pattern at KLZU, which is 1061 MSL, I love the Grummans, but I don't think an AA1 would be a good aircraft for high DA situations.
 
k9medic said:
I flew a AA1 from Florida to New Hampshire years ago for a client. If I with two of us, we had to share a toothbrush because packing a second one would put us over weight...

I had a Grumman AA5 traveler. It has the similar wing as the AA1. It's for sale at almost the same price point as some AA1's. I would be looking in that direction.
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An AA-5 or AA-5A with the high compression STC would give you much more performance margin for 2 plus luggage travel. AA-5s are usually quite affordable. 4+30 fuel makes it adequate for functional IFR.
 
chemgeek said:
An AA-5 or AA-5A with the high compression STC would give you much more performance margin for 2 plus luggage travel. AA-5s are usually quite affordable. 4+30 fuel makes it adequate for functional IFR.
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Yep. My AA5 has the upgrade as well as a cruise prop and STEC 40 autopilot. Makes for a nice 2 place plus baggage plane.
 
Just joined this forum. I owned an AA-1C with a 160 hp engine for many years (as well as all the other single engine Grummans) and it would perform very well at high density altitudes, but it doesn't have enough useful load and fuel for your stated mission. If it had the extra 10 gal tanks it would then only be a single place plane. So, the previous post quote by chemgeek is spot on and an AA-5 or better yet an AA5A with the HC engine STC would be a good 2 place plane for high DA and long range capability. It would be noticeably faster than a Cherokee, except a 180 hp version and more fuel efficient, plus lots more fun to fly.
 
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