student weight balance question

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brooklyn26point2

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brooklyn26point2
likely a dumb question, but given the priority given to safety issues i figure it's worth an ask. I'm taking flight lessons in a warrior, and I'm 5'5 and 150 lbs. My instructor is 6'+ and 215lbs. Does a weight differential create a concern of an imbalanced aircraft?

thanks!
 
brooklyn26point2 said:
likely a dumb question, but given the priority given to safety issues i figure it's worth an ask. I'm taking flight lessons in a warrior, and I'm 5'5 and 150 lbs. My instructor is 6'+ and 215lbs. Does a weight differential create a concern of an imbalanced aircraft?

thanks!
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In reality no. You are both very close in proximity (I'm sure you know that by now). You should never really notice this. You'd sooner notice flying with on tank empty and the other full. Think back to your school days and the use of levers and fulcrums.

All the really smart people will be along shortly to dazzle you.
 
That's what I figure, and makes perfect sense. We're both centered enough that the effect is likely to be negligible if in existence at all. Thanks!
 
My instructor was pushing 230. When I solo'd the tower called me after takeoff and asked if it didn't fly a lot better without the fat guy in the right seat.
 
Cherokees are very nice flying machines to train in.

You and your instructor are 365 together another 200-300 lbs in the wing fuel tanks.

I found that if I get a case of water bottles and put it in the hat rack or stowage then the plane flies and lands a bunch better.

I'm not sure you are outside of forward limit but you are definitely very close to the forward line. It is a good exercise to go ahead run the numbers a few times with different loadings.

As far as differential from left seat to right seat it is not that important as you are both so close to the center of gravity. however you will notice when you have 15 more gallons of fuel in one wing than in the other you will have to adjust for it.

I recommend burning off the fuel from the Instructors side first since his side is a bit heavier already. I was heavier than my instructor so I think we ran 1 hr left and 1 hour right.
 
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Tony_Scarpelli said:
Cherokees are very nice flying machines to train in.

You and your instructor are 365 together another 200-300 lbs in the wing fuel tanks.

I found that if I get a case of water bottles and put it in the hat rack or stowage then the plane flies and lands a bunch better.

I'm not sure you are outside of forward limit but you are definitely very close to the forward line.

It is a good exercise to go ahead run the numbers a few times with different loadings.
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Tony is correct here. The two of you in the front will make the plane have a fairly forward CG.
 
brooklyn26point2 said:
likely a dumb question, but given the priority given to safety issues i figure it's worth an ask. I'm taking flight lessons in a warrior, and I'm 5'5 and 150 lbs. My instructor is 6'+ and 215lbs. Does a weight differential create a concern of an imbalanced aircraft?

thanks!
Click to expand...

It's only a problem if you stuff him in the cargo area. That's limited to 120 lb. And while it's occasionally tempting, it doesn't make for very good lessons that way. :)

You'll get a bigger weight differential just by switching tanks on a 1 hour schedule. It's not significant.
 
Thanks everyone for the response! Tony, I had not thought about the fwd vs aft weight balance - thanks for pointing it out. But, is it more significant than 2 180-pounders (slightly less than the average male weight in the US)?
 
brooklyn26point2 said:
That's what I figure, and makes perfect sense. We're both centered enough that the effect is likely to be negligible if in existence at all. Thanks!
Click to expand...

It is negligible in most cases but, always in existence unless perfectly balanced.

At high DA, out of very short airstrips, with the need for a turn immediately after liftoff, using moveable weights to adjust lateral CG to favor the turn can be very advantageous, even critical.
 
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brooklyn26point2 said:
Thanks everyone for the response! Tony, I had not thought about the fwd vs aft weight balance - thanks for pointing it out. But, is it more significant than 2 180-pounders (slightly less than the average male weight in the US)?
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Time to do some research on weight and balance on your particular plane and come up with an answer. :wink2:
 
flyingron said:
My instructor was pushing 230. When I solo'd the tower called me after takeoff and asked if it didn't fly a lot better without the fat guy in the right seat.
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They don't have to be fat for the airplane to fly much better at solo.

My instructor was barely 120 lb, and the 172N practically leaped off the ground solo.
 
Your instructor weighs 65 lbs more than you do. The center of your bodies are about 1 foot from the centerline of the plane on opposite sides. Since he is sitting in the right seat, you will have about 65 foot pounds of moment trying to rotate the plane right side down. If you weighed the same and followed the Piper fuel tank switching recommendations, you would burn about 50 pounds of fuel out of the selected tank before you switch tanks. The tanks are roughly 6 feet from the centerline of the plane out in the wing. That is about 300 foot pounds of moment trying to rotate the plane away from the right tank. That is not a problem and is significantly more turning moment than just that caused by the difference between your weight and that of your instructor.
 
EppyGA said:
Time to do some research on weight and balance on your particular plane and come up with an answer. :wink2:
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Fair enough, I was being a bit lazy there.

We seem to be on the edge of the envelope with full fuel and nothing in the back. Take away some fuel, but 30 pounds of something in the back seat and we get into a more comfortable zone.
 
EppyGA said:
Tony is correct here. The two of you in the front will make the plane have a fairly forward CG.
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As GauzeBuy discovered this morning, two heavy people (ok, so I need to lose weight, what can I say?) in a cherokee definitely takes off better with weight in the baggage area. I keep 7 gal of water in an 8 gal tank back there. Double duty - if something happens in the summer, there's emergency water. And unlike stashing a case of oil back there, if I need to get rid of the extra weight it doesn't bother me to pour it out.
 
brooklyn26point2 said:
likely a dumb question, but given the priority given to safety issues i figure it's worth an ask. I'm taking flight lessons in a warrior, and I'm 5'5 and 150 lbs. My instructor is 6'+ and 215lbs. Does a weight differential create a concern of an imbalanced aircraft?

thanks!
Click to expand...

It's never a dumb question.
 
The side to side balance issue will be far less than if you are flying solo in the plane too. Even if there's a bit of a bank towards one side you will subconsciously level out with a bit of opposite aileron. I also haven't ever flown a plane whose yoke is perfectly centered in straight and level flight.
 
One way to ease the forward CG issue is to have the heavy passenger slide his seat all the way back. There is a Piper document re-issued by the FAA on spinning Cherokees that takes credit for seat fore and aft position. The standard front seat moment arm is the center hole in the track. You can increase the seat moment arm by 1.5 inches for each hole aft of center. The CFI is more than a passenger though and needs to be positioned to handle the controls so all the way back may not be an option.
 
Graueradler said:
One way to ease the forward CG issue is to have the heavy passenger slide his seat all the way back. There is a Piper document re-issued by the FAA on spinning Cherokees that takes credit for seat fore and aft position. The standard front seat moment arm is the center hole in the track. You can increase the seat moment arm by 1.5 inches for each hole aft of center. The CFI is more than a passenger though and needs to be positioned to handle the controls so all the way back may not be an option.
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Makes sense. The quasi-automated spreadsheets I've seen online don't allow for different positions of the 2 front seats, but definitely makes sense. He'll be the bulk of the weight and much taller than me, so I'm guessing he'll move back a little, thus evening out the plane a little.
 
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