Heavy and aft loaded, but within envelope

S

slavinger

Pre-Flight
Joined
Dec 30, 2013
Messages
64
Location
In the sky
Display Name
Display name:
yippie
Hi all, my first post to PoA boards. I fly a PA-28-181 and have a flight coming up that I'm unsure whether to go or cancel. CG is within the published envelope, however it's pretty close to the edge, and I haven't flown this close to the published limit before. Archer II normal cat. limits are 2550 lbs and 93" aft, in this case I'm at 2525 lbs and 92.3", and can't really rearrange passengers (going with another pilot who wants to sit up front, and 2 non-pilots in the back). I'm current and proficient (fly usually somewhere in the middle CG-wise). Part of me wants the experience of handling the plane throughout the entire envelope, and part of me wants to be safe and cancel. So, how risky is this, really? I've already read up on what to watch out for, but looking for first-hand experiences. Should also mention that temps and runway lengths aren't an issue, it'll be cold and these are major airports with long runways. Thanks.
 
It's within W & B, and within the CG limits? Why not?

Just make sure it will stay within CG throughout the flight. As you burn fuel, the CG will shift. In my plane, the CG will generally shift backwards as the fuel burns. So that could take you out of CG.
 
That envelope is necessarily conservative. I'd have no qualms about flying at any point in/on it, especially in such a docile plane. Performance is noticeably better with aft CG. Just remember to use your trim.
 
If you're within limits, you're within limits.

It may however be an occasion to get a scale for baggage/whatever other junk goes in the back!
 
Go for it, add 10 - 15 mph on final approach. Floating a little when heavy is a good thing. JMHO.
 
FWIW, most flying done for purposes of utility is done at near max gross weight. Planes are designed to operate normally at the edges of their W&B envelope. You should have no concerns operating, provided you stay within the envelope as you burn off fuel, and have calculated sufficient runway length for take off and landing.
 
Geico266 said:
Go for it, add 10 - 15 mph on final approach. Floating a little when heavy is a good thing. JMHO.
Click to expand...

Do that in the Comanche, and you'll be going around on a 3,000' runway.
 
You're within limits. If you want to practice first, get some sand bags and load them up to simulate and take a flight before hand.
 
Thanks a lot everyone, wow this is a busy place! :) Burning off fuel moves CG forward in Archers (although not by much - with zero fuel CG is at 92).
 
Norman said:
Recalculate W&B with minimum fuel and see if you're still within limits.
Click to expand...

N5922S said:
That envelope is necessarily conservative. I'd have no qualms about flying at any point in/on it, especially in such a docile plane. Performance is noticeably better with aft CG. Just remember to use your trim.
Click to expand...

:yes:
 
Welcome to the board,like stated before check the w&b after fuel burn .
 
Geico266 said:
Go for it, add 10 - 15 mph on final approach. Floating a little when heavy is a good thing. JMHO.
Click to expand...

Why would you do that?

Fly the numbers, don't get slow, because you'll have more momentum to overcome. You won't need as much up elevator force in the flare with the aft CG. If you give it the same amount of "pull" as you do at light weights/forward CG, you'll likely balloon the flare and stall it onto the runway (ask me how I know...first time I landed a 172 with a full load...)

Don't be tempted to approach/land fast, all that will do is increase the likelihood of trying to force it on the runway, land on the nosegear and/or bounce it.

Fly the same stabilized approach you're (hopefully) used to flying.
 
EdFred said:
Do that in the Comanche, and you'll be going around on a 3,000' runway.
Click to expand...

Exactly - there is no reason whatsoever to speed to an aircraft inside the envelope -

In a Comanche you might go around on a 5000' runway doing that . . .
 
Remember that you will not have the same climb performance....It will take longer to get to your preferred altitude. I did this a few weeks ago in a cherokee 180. Very cool day, within W&B and CG and 4 adults. Very slow climb to 9500 MSL (started at 5800 MSL). Didn't want to scare the folks in the back seat.
 
The plane will handle it fine but be aware your sink rate will be higher in the flare. In other words it will take a little more to arrest the sink when you flare and you might thump onto the runway. Just flare a very little sooner and round out smoothly. You will have no problems.
 
Vaflier said:
The plane will handle it fine but be aware your sink rate will be higher in the flare. In other words it will take a little more throttle to arrest the sink when you flare and you might thump onto the runway. Just flare a very little sooner and round out smoothly. You will have no problems.
Click to expand...

FTFY.;) power arrests sink.
 
Geico266 said:
Go for it, add 10 - 15 mph on final approach. Floating a little when heavy is a good thing. JMHO.
Click to expand...
That's OK if you also add 20-30% to your "usual" runway length minimums. Otherwise it's a good way to run out of runway. While the POH numbers for takeoff and landing distance are rather optimistic for everyday use and should be padded, the speeds are usually right on for landing at MGW and no padding should be required.
 
First, not many (if any) production-certified light planes can fuel-burn themselves out of the cg envelope and I'm pretty sure the PA28 isn't one of them. Other than that, realize the performance (especially takeoff and climb) will be less than you're used to, and the airplane will be more sensitive in pitch than you're used to. So, be conservative in your planning, and be gentle on the controls, and you should be fine. But if you're still not sure, take a CFI up for a trip or two around the pattern with that full gross/aft load and see how it feels.
 
Geico266 said:
Go for it, add 10 - 15 mph on final approach. Floating a little when heavy is a good thing. JMHO.
Click to expand...
This is really bad advice. The most you'd need to add to your usual final approach speed with an extra two people aboard is 3-4 knots. Adding more than that is an invitation to all sorts of problems you don't want to have, including porpoising and bouncing, as well as needing an astonishing amount of extra distance to land.
 
With aft CG you're probably going to go faster so if someone is meeting you at the destination you might have to wait a few minutes for them. :wink2:
 
And remember that when you flare with the CG so far back, the stabilator controls will feel a bit lighter, and the nose will be a lot more willing to point up. Just be cognizant of that, and don't let it surprise or startle you.
 
jshawley said:
And remember that when you flare with the CG so far back, the stabilator controls will feel a bit lighter, and the nose will be a lot more willing to point up. Just be cognizant of that, and don't let it surprise or startle you.
Click to expand...

Proper training eliminates that sort of "surprise". :yesnod:
 
Greg Bockelman said:
Proper training eliminates that sort of "surprise". :yesnod:
Click to expand...

Yes it does. However, what you (and I too) would consider proper training exceeds the requirements of the FAR and also is not what most folks receive for primary training.

To the OP:
Be nice and smooth on the controls, especially pitch. you should have learned that an aft CG increases efficiency but decreases pitch stability (but not to the point where the airplane is difficult to fly, it's just "different", the controls will feel lighter in pitch). Don't add any extra airspeed to your approach, or use less flaps, or any other such nonsense. Be sure your climb performance at max weight is adequate for any obstacles, and expect the decrease in climb rate. Good advice to go up with a CFI and some sandbags (or airport hanger-ons, human sandbags!) if you want the experience before taking your trip, but you should not be anything beyond normally cautious when flying a PA28 within the CG envelope.

Best wishes,
 
Ditto on the pitch comments. Still remember just after getting PPL 42 years ago my first flight with Dad in a PA28 160 (he's 6'5" and a bit heavy to boot). Took off as usual, and got a stall warning just after lifting off. Today I'm flying a PA 32 with nearly 3/4 ton useful load - at gross to a difficult runway - Catalina Island. I just am a bit more careful and gentle..works every time!
 
You must log in or register to reply here.
Back
Top