Iffy...need advice

[SkyHog]

Ok, now I have a heavyset friend of mine (hell, I'm heavyset too), and he wants to go flying with me. I know he'll have a good time. I want to carry enough fuel to get us somewhere. With 35 gallons of fuel (there and back without refueling hopefully), I get the weight and balance envelope to look like this...would you do it? (where the two blue lines meet is my point)

 

[rpadula]

Throw a 50 lb bag of sand in the way back?

Looks like you've got enough weight margin...


-Rich

 

[grattonja]

Done something pretty close to that in a 172SP with a heavy friend from work. It was no problem, required just a bit more nose up on flare and flew ever so slightly nose high. If I am reading your chart right, anyway, you are at the front of the CG envelope, but just within. No worries.

Jim G

 

[stcurtis]

Looks like it would work. Have you done W&B with some weight as far back as possible? I would look at a W&B once you've burned the fuel out of the tanks, if you are still within the limits, have fun.

I've flown similar profile in my 172S, and had no problems. trim, trim, trim.

Steve

 

[gismo]

Ok, now I have a heavyset friend of mine (hell, I'm heavyset too), and he wants to go flying with me. I know he'll have a good time. I want to carry enough fuel to get us somewhere. With 35 gallons of fuel (there and back without refueling hopefully), I get the weight and balance envelope to look like this...would you do it? (where the two blue lines meet is my point)

JOOC what's the plane?

When at or very near to a limit (aft in this case) it's wise to dig a bit deeper. Consider the seat position for instance. With big guys it may be all the way back, but you can measure it with a tape or ruler to be sure. The POH should say what the range for the pilot's seat is and you can generally assume that the forward end of the range corresponds with the forward most position of the seat. It's also wise to consider the CG with minimum fuel as it often moves as fuel burns off. Most Cessnas burn forward which would help in your case. It would be useful to know how accurate the current W&B report for the airplane is. If it's been weighed within the last couple years, chances are it's pretty close, but if the last time it was actually weighed was before it left the factory you can expect some error for which you may want to add a little margin. If you've flown this and others of the same make/model you might have a feel for whether this one feels more nose or tail heavy than the "norm". Finally, when at the aft limit you may want to clean out the junk stored in the aft baggage as even 10 lbs of stuff can make a noticeable difference in the actual CG of a small plane.

As to would I go, the answer is yes if I knew the calculation was accurate (see above). With a fully aft CG you should expect the stick force per G load to be significanly less than you have experienced with forward loading and that means airspeed control will be more difficult than usual and there is a tendency to bobble in pitch during the landing flare. Make sure you set the takeoff pitch trim a bit more nose down than you would normally use and expect it to be easier to lift the nose too high when rotating. Other than that, as long as you are truly within the published CG limits. Those limits do have some built in margin so you needn't worry that the plane will fall out of the sky or become uncontrollable just because you are on the limit. That doesn't mean you should push beyond the limits as the margins are there to cover the inaccuracies not a wish to fly "a little out of CG".

Edit: Am I reading the graph backwards and you are at the forward limit? If so you may find that the CG goes beyond the limit when fuel is burned, definitely worth checking. Also since you are well below the MGW, it wouldn't take much weight tied down as far aft as possible to push the CG back a little. The control issues will be just the opposite with higher stick forces, and a tendency to land flat. Trim more nose up for takeoff or you may end up wheelbarrowing down the runway.

 

[MSmith]

I agree with the above - check no-fuel W&B and if you're still in the limits you're fine.

I had to bring my wife along as ballast on a flight to take her father up. Two big guys in the front seat requires something in the back (and less fuel). In a Warrior with the battery in the engine compartment, I was OK at 40 gallons (though not at 48), but only with my wife.

 

[Greebo]

Ditto - I'm a big guy and my brother in law is bigger than me. W&B checked out ok, empty and full. Just used a little extra nose up trim.

 

[poadeleted3]

So long as I can satisfy myself that I'll be within limits in all phases of flight, I'll go as long as I'm anywhere inside the lines on the chart. If I'm close to the limits, though, I check things like seat position, and always check full fuel and zero fuel.


FWIW, with Cathy and I up front in a Skyhawk SP or a Tiger, we're quite close to the forward limit. Never a problem.

 

[wsuffa]

Ok, now I have a heavyset friend of mine (hell, I'm heavyset too), and he wants to go flying with me. I know he'll have a good time. I want to carry enough fuel to get us somewhere. With 35 gallons of fuel (there and back without refueling hopefully), I get the weight and balance envelope to look like this...would you do it? (where the two blue lines meet is my point)

It's in the envelope, at least as I read it.

Yep, I'd do it. Some planes will put you on the forward side with two up front.

Or you can throw a little weight in the back to be sure.

What happens to the CG as you burn off fuel?

 

[Brian Austin]

What happens to the CG as you burn off fuel?

Yup. You should be doing a CG check at takeoff, mid-cruise and landing weights to confirm that you'll stay inside the envelope.

That said, I've flown there with no problems in both a 172R and S model. I did move my flight bag from the back seat to the baggage but I'm not sure it was that significant.

 

[SkyHog]

Yup. You should be doing a CG check at takeoff, mid-cruise and landing weights to confirm that you'll stay inside the envelope.

I actually did....and tried to edit the post to reflect that last night, but t just happened to be at the mantenence time. I had to go to sleep.

But, it's just as close after the fuel burn:

 

[MSmith]

You've got the total weight room - I'd throw a 50lb sandbag in the baggage area.

 

[Brian Austin]

You've got the total weight room - I'd throw a 50lb sandbag in the baggage area.

I agree. It would make your landing flares a little easier.

 

[SkyHog]

Good idea - Sandbag it is. Do I have to strap the sandbag down or anything, to avoid it becoming a missile in an emergency situation?

 

[Jim Chumley]

Ok, now I have a heavyset friend of mine (hell, I'm heavyset too), and he wants to go flying with me. I know he'll have a good time. I want to carry enough fuel to get us somewhere. With 35 gallons of fuel (there and back without refueling hopefully), I get the weight and balance envelope to look like this...would you do it? (where the two blue lines meet is my point)

Sure, I'd go, assuming you calculated correctly. Bet you did it more than once. That's what the W&B is for. You are inside the envelope. Check density altitude, too.

Jim

 

[MSmith]

IF you use one of those Home Depot-style flat sandbags, it shouldn't launch into the front of the cockpit (unless you're planning aerobatics!). It'll be heavier than your flight bag.

 

[AirBaker]

I'd agree with the weight in the back and it helping with the landing flare. Having a nose heavy aircraft at the slow speed might require some extra convincing to flare.

My dad's 206 almost always has a 50lb bag of sand in the back. Its only removed when fully loaded for similar envelope issues.

I wouldn't worry about straping it down. You might even be able to find a 20lb weight to put back even further if the 172 will allow for it.

 

[poadeleted3]

I actually did....and tried to edit the post to reflect that last night, but t just happened to be at the mantenence time. I had to go to sleep.

But, it's just as close after the fuel burn:

I quit doing a landing weight check, and now do a zero fuel check instead. What happens if I've gotta go somewhere else, or end up having to loiter for a crash on the runway or something? If you check zero fuel, you'll know you won't be out of limits as long as the plane is in the air. IMHO, anyway.

 

[gismo]

I wouldn't worry about straping it down. You might even be able to find a 20lb weight to put back even further if the 172 will allow for it.

If you just toss the bag of sand or weight in the back, it could kill you if you had an otherwise survivable accident. In addition, it will slam the cabin floor if you hit some serious turbulence, and damage can occur. Worse yet it could pound the floor into the control cables for the elevator and rudder. Either secure it with tiedowns or jam it in place with other stuff so it can't move far.

 

[wsuffa]

If you just toss the bag of sand or weight in the back, it could kill you if you had an otherwise survivable accident. In addition, it will slam the cabin floor if you hit some serious turbulence, and damage can occur. Worse yet it could pound the floor into the control cables for the elevator and rudder. Either secure it with tiedowns or jam it in place with other stuff so it can't move far.

Shall we rehash the question of whether the cargo net is required equipment in the plane???

 

[Let'sgoflying!]

also consider takeoff conditions (rwy type & length, DA)

 

[gismo]

Shall we rehash the question of whether the cargo net is required equipment in the plane???

You'll notice I included the option of jamming the ballast in place with other stuff. I hardly ever use the cargo tiedowns in the Baron other than the web barrier that covers the extended aft compartment as we usually have so much junk along that nothing but the snacks on top could move when the doors are closed.

 

[Henning]

Ok, now I have a heavyset friend of mine (hell, I'm heavyset too), and he wants to go flying with me. I know he'll have a good time. I want to carry enough fuel to get us somewhere. With 35 gallons of fuel (there and back without refueling hopefully), I get the weight and balance envelope to look like this...would you do it? (where the two blue lines meet is my point)

You'll be ok, although if the handling is funky and nose heavy at low speed, just have him slide his seat all the way back.