2 Questions about a Cherokee 180 Archer (RPM & useful load)

hish747

hish747

Pre-takeoff checklist
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Hish747
I'm looking at entering into a partnership on a 1974 Cherokee 180 Archer and wanted to get your thoughts on a couple of questions.

During takeoff the engine was only developing around 2300rpm. The weather was a hot and humid 90 degrees and density altitude was around 2200 ft. Does the rpm seem normal under the circumstances?

This particular airplane claims a useful load of only 919 pounds. This seems low for a 180. As far as I can tell the only additional equipment are Autocontrol IIIB, Garmin 430 and electric trim. Thoughts?
Thanks,
Hish
 
Check your rpm at full throttle while on the ground brakes locked. It should be near 2300. There is a small permitted range but I forget the exact numbers. This "static runup" rpm should be in your POH. There are too many variables to perform this test on climb out.

Yep, some of the older planes have low useful loads. The only way to know for sure is to have your plane weighed now or at next annual inspection.

-Skip
 
Per the TCDS, Section XII at p. 16:

Static r.p.m. at maximum permissible throttle setting not over 2425 r.p.m., not under 2325 r.p.m. No additional tolerance permitted.
Click to expand...

Gross weight on the '73-'75 Challenger/Archer (Hershey-bar wing) is 2450 lb, 100 less than the taper-wing Archer II, so it's not a huge load hauler. Good news is that it's easy to fuel only to the tabs (36 gal.) instead of full (50 gal.), so you have an extra 84 pounds to play with on shorter flights.
 
The Cherokee I fly only makes 2200-2300 as you start to roll. That picks up to the full 2500 for climb at about the time you lift off.

So 2300 on the takeoff roll is probably normal.

919 isn't terrible for an Archer. They are usually 900-1000 pounds with useful load.
 
hish747 said:
I'm looking at entering into a partnership on a 1974 Cherokee 180 Archer and wanted to get your thoughts on a couple of questions.

During takeoff the engine was only developing around 2300rpm. The weather was a hot and humid 90 degrees and density altitude was around 2200 ft. Does the rpm seem normal under the circumstances?

This particular airplane claims a useful load of only 919 pounds. This seems low for a 180. As far as I can tell the only additional equipment are Autocontrol IIIB, Garmin 430 and electric trim. Thoughts?
Thanks,
Hish
Click to expand...

Any time you have a discrepancy on RPM and a mechanical tach, the first thing you do is verify the tach accuracy. Mechanical tachs have a magnetic field coupling to pull the needle against a spring. After a couple of decades everything changes a bit and you have to take the tach to a speedometer shop so they can recalibrate it by adjusting the gap between the magnets. It's common for an older tach to be 150-200 rpm low.

As for weight, have the plane re-weighed.
 
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I fairly regularly fly on archer and those numbers all seem about right.
 
I think it was around the mid-1970's that the Cherokee 180 became the Challenger then the Archer, with a slightly larger fuselage. They increased the backseat space but it also decreased the useful load. 919 lbs sounds about right.

I have been looking at Cherokee/Archers and also at C172's with a 180 conversion. One 172/180 I really like never got the STC when they upped the HP, so the official useful is down in the 700's. Ugh. It should have no problem holding 900 lb, but until it becomes official I just can't do it.
 
I owned a 180 and the numbers work just fine.
 
DrPappy said:
I think it was around the mid-1970's that the Cherokee 180 became the Challenger then the Archer, with a slightly larger fuselage. They increased the backseat space but it also decreased the useful load. 919 lbs sounds about right.
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1973 was the year model for the PA-28-180 Cherokee Challenger, with lengthened fuselage, PA-32-size stabilator, and 12" inserts added to the wings between the outboard ends of the ailerons and the wingtips, to make the wingspan the same as the PA-28-235.

Chrysler Corp. squawked about Piper's use of its muscle car names (the '73 -235 was "Charger"), so for 1974 and 1975 the PA-28-180 was "Cherokee Archer". For 1976 it got the Warrior's tapered wing and became "Cherokee Archer II"; the "Cherokee" name was dropped after the 1977 model year.

One 172/180 I really like never got the STC when they upped the HP, so the official useful is down in the 700's. Ugh. It should have no problem holding 900 lb, but until it becomes official I just can't do it.
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That's the way mine is. I have both the engine and flap/MGW STCs, but the flap limiter is still sitting in my desk. So I still have all 40° of flap and the original 2300 lb gross weight, for a useful load of 767 lb.

That's OK; I like short fields, I have no friends, and the tanks only hold 40 gallons anyway. :)
 
I fly a club Archer III, (2002 I think) - useful load 750lbs. Everything gets fatter over the years.
 
Pilawt said:
Per the TCDS, Section XII at p. 16:







Gross weight on the '73-'75 Challenger/Archer (Hershey-bar wing) is 2450 lb, 100 less than the taper-wing Archer II, so it's not a huge load hauler. Good news is that it's easy to fuel only to the tabs (36 gal.) instead of full (50 gal.), so you have an extra 84 pounds to play with on shorter flights.
Click to expand...


Tabs on the '73 challenger/archer are 17 gal each for total of 34. (Not 36) Just a minor note. 2300 rpm on takeoff roll is what I get (maybe 2330).


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Too many variables including whether is was leaned properly, tach is accurate, etc..

2200 DA isn't that high, you must be at sea level somewhere?
 
you didn't say whether the prop has been changed or re-pitched
 
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