Weight

chemgeek said:
The funny thing about aircraft W&B is that the W is almost always underestimated from the actual weight. So 20 lb over is maybe 50 lb over or even more. Plus, did you really add up all the extra weight from the tools and other crap loaded in your plane? Couple that with an engine that doesn't put out book power anymore, piloted by an owner who isn't test-pilot quality, at ambient conditions that are not "standard," where is your safety margin at? If you have to fly over-gross to get utility out of our plane, you have the wrong plane.
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Yes. And I don't know about new ones, but if you're flying a 30+ year old plane and you think it's going to meet the short field take off charts in the back of the POH, either you're kidding yourself or I've been reading different charts than you.
 
chemgeek said:
The funny thing about aircraft W&B is that the W is almost always underestimated from the actual weight.
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Not long after buying my plane, I went through all the historical W&B info I could find. The W&B sheets do not correlate very well with the logbook entries, and I have all the logs dating back to 1969. I found some simple arithmetic errors (which I've since corrected), but did I find all the errors? How could I possibly know? There have been equipment additions and removals over the years that should have included updates to the W&B sheet, but either they didn't or I don't have all the revisions of the weight sheets.

My only real way to know where things stand would be to re-weigh the plane, another error-prone process. So, not having 100% faith in the empty weight data, certainly not to within a pound or two, I act conservatively and I don't push the limit. Load the plane to 20lbs over? Hah! For all I know, I might already be at the limit when I think I'm 20lbs under.

chemgeek said:
Plus, did you really add up all the extra weight from the tools and other crap loaded in your plane?
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Yes, actually. I weighed my tool bag, my RON bag, my tie-downs, etc. But I don't step on a scale before every flight, I don't add in the 1/2 lb $100 hamburger I just ate, and I don't weigh my wife (fear, not of divorce but of murder). All the more reason to be conservative and not push the limit.
 
Albany Tom said:
Yes. And I don't know about new ones, but if you're flying a 30+ year old plane and you think it's going to meet the short field take off charts in the back of the POH, either you're kidding yourself or I've been reading different charts than you.
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My almost 80yr old plane preforms to book or better, and I’ve measured my takeoff rolls out of our grass strip, trued out my IAS, etc.

Just a matter of maintenance and operations
 
Half Fast said:
My only real way to know where things stand would be to re-weigh the plane, another error-prone process.
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I had my plane reweighed after I restored it. There's a guy in the area who specializes in it. For 200 bucks he shows up with a set of calibrated portable scales and plugs the data into a laptop to give you a new W&B.
 
decalogue said:
My almost 80yr old plane preforms to book or better, and I’ve measured my takeoff rolls out of our grass strip, trued out my IAS, etc.

Just a matter of maintenance and operations
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…and actually determining how much runway was used, and using proper technique. Two things that are generally lacking from what I see.
 
MauleSkinner said:
…and actually determining how much runway was used, and using proper technique. Two things that are generally lacking from what I see.
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I agree there

It is fun though, pretty easy too if you have a handy laser range finder and some friends on a grass strip

With short fields I have found it’s often the Indian not the arrow
 
I would want to see this 20lbs expressed as a percentage of MGW to have an opinion.
 
decalogue said:
My almost 80yr old plane preforms to book or better, and I’ve measured my takeoff rolls out of our grass strip, trued out my IAS, etc.

Just a matter of maintenance and operations
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Mine is 75 and it'll do better than book value every day of the week. The extra wing tips and 30HP and longer prop make all the diff.
 
Albany Tom said:
Yes. And I don't know about new ones, but if you're flying a 30+ year old plane and you think it's going to meet the short field take off charts in the back of the POH, either you're kidding yourself or I've been reading different charts than you.
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This isn't really true, my plane easily beats the short field takeoff AND landing
 
Salty said:
The real question is….

If you’d fly over weight would you post that you would on the internet?
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Folks text their tinder dates their illegal drug use, soo
 
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Ed Haywood said:
I had my plane reweighed after I restored it. There's a guy in the area who specializes in it. For 200 bucks he shows up with a set of calibrated portable scales and plugs the data into a laptop to give you a new W&B.
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Did you empty the fuel tanks?
 
bonefishpete said:
Top them off then deduct usable?
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I could put an extra 1.5 gallons in my tanks, this makes sense, can you imagine what a lawyer would make of a airplane manufacturer if the tanks were even an ounce short? I would think this would be common. So using your method, I would lose 9lbs of useful load.
 
MooneyDriver78 said:
I could put an extra 1.5 gallons in my tanks, this makes sense, can you imagine what a lawyer would make of a airplane manufacturer if the tanks were even an ounce short? I would think this would be common. So using your method, I would lose 9lbs of useful load.
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In for how the weight and balance people do it. I doubt they drain the tanks?
 
To note, the TCDS will have the requirements of what must be included in an aircraft certified empty weight which older aircraft tend to have different requirements than newer aircraft. That new empty weight also is required to have a current equipment list to go with it.

As to draining the fuel tanks before an actual weight and balance, there can be several items that can influence that decision like OEM weigh data for full fuel, OEM weighing procedures, or even a mechanics preference. Personally, I drain the fuel, refill the required unusable per the TCDS, then weigh it. And for some customers we would recheck the fuel quantity system when refilling the fuel tanks to full.
 
decalogue said:
My almost 80yr old plane preforms to book or better, and I’ve measured my takeoff rolls out of our grass strip, trued out my IAS, etc.

Just a matter of maintenance and operations
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MackMooney said:
This isn't really true, my plane easily beats the short field takeoff AND landing
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I believe you guys if you're telling me that your aircraft performs to the takeoff charts in the POA. I do. And if you're flying your aircraft out of short fields and you can trust your book numbers to be OK for your aircraft, I respect that, too. But my experience with club and rental aircraft, that hasn't been the case.

I'll be more specific, I've found it to be 150 HP PA-28s, and more specifically the obstacle clearance distances on take off. This is stubby and taper wings, and including aircraft that have recently overhauled engines. Landing are fine, takeoff without obstacles are fine, short field take off with obstacles? Nope. Now I don't know if they're all a little heavy, or they're rigged a little crooked, or the props aren't quite the right shape, or my technique is lousy...but I fly out of a relatively short field, and I don't make the book numbers.

I still stand by trust but verify on takeoff performance numbers, including aircraft that you know otherwise fly perfectly. If you know your own aircraft, and it'll do it, then of course that's a different thing.
 
Albany Tom said:
I believe you guys if you're telling me that your aircraft performs to the takeoff charts in the POA. I do. And if you're flying your aircraft out of short fields and you can trust your book numbers to be OK for your aircraft, I respect that, too. But my experience with club and rental aircraft, that hasn't been the case.

I'll be more specific, I've found it to be 150 HP PA-28s, and more specifically the obstacle clearance distances on take off. This is stubby and taper wings, and including aircraft that have recently overhauled engines. Landing are fine, takeoff without obstacles are fine, short field take off with obstacles? Nope. Now I don't know if they're all a little heavy, or they're rigged a little crooked, or the props aren't quite the right shape, or my technique is lousy...but I fly out of a relatively short field, and I don't make the book numbers.

I still stand by trust but verify on takeoff performance numbers, including aircraft that you know otherwise fly perfectly. If you know your own aircraft, and it'll do it, then of course that's a different thing.
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For a rental, that doesn’t really surprise me

I have found though that most planes run out of pilot well before they run out of plane

Obstacle takeoff is a good example, I’ll see many pilot yank the plane off the runway as soon as possible and pitch for VX
Vs
Breaking ground and staying in ground effect till the end and then transferring that energy into a modulated pitch back to vx
 
decalogue said:
For a rental, that doesn’t really surprise me

I have found though that most planes run out of pilot well before they run out of plane

Obstacle takeoff is a good example, I’ll see many pilot yank the plane off the runway as soon as possible and pitch for VX
Vs
Breaking ground and staying in ground effect till the end and then transferring that energy into a modulated pitch back to vx
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Book numbers only apply directly to book technique. Changing from that technique may result in improvement or degradation, but one of the more important aspects is to understand whether or not one is actually doing something different than book technique.
 
MauleSkinner said:
Book numbers only apply directly to book technique. Changing from that technique may result in improvement or degradation, but one of the more important aspects is to understand whether or not one is actually doing something different than book technique.
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You think using ground effect is going to degrade performance in the scenario in question?
 
decalogue said:
You think using ground effect is going to degrade performance in the scenario in question?
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Probably.

If you smoothly rotate and climb at Vx right away, yes you have some additional drag compared to being in ground effect.

However, staying in ground effect, while you have less drag for a very short extra period of time before parasitic drag from the extra speed means you have even more drag even though you're in ground effect, and now you have no altitude. Sure, you can pull back into a zoom climb and gain some altitude, but it will be less altitude than you would have gained by remaining at Vx.
 
flyingcheesehead said:
Probably.

If you smoothly rotate and climb at Vx right away, yes you have some additional drag compared to being in ground effect.

However, staying in ground effect, while you have less drag for a very short extra period of time before parasitic drag from the extra speed means you have even more drag even though you're in ground effect, and now you have no altitude. Sure, you can pull back into a zoom climb and gain some altitude, but it will be less altitude than you would have gained by remaining at Vx.
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Respectfully disagree on that last part

Good book on this type of flying


“In the takeoff phase of every flight the main concern is getting airborne and rudder turning around or clearing any departure obstructions. With airplanes we have to consider the surface of the runway. Roughness in the first three hundred feet will slow our acceleration, but when we have accelerated to partial buoyancy, a rough section of the field might help bounce us off into ground effect flight.

It is a good habit to get off the surface (with flaps if we have them) and into low, level ground effect as soon as possible. Once off the surface and in ground effect, the remaining takeoff surface condition is of little consequence.

We should accelerate in low ground effect through stall speed, through Vx, through Vy, to a reasonable zoom reserve in the form of airspeed (we acquire this comfortable feeling through all our senses) prior to leaving low ground effect.

To leave ground effect sooner than absolutely necessary is unwise because of our poor engine power in comparison with the power of temperature, wind shear, humidity, density altitude, and gravity.
Natural laws have more power than our engine.”
 
decalogue said:
You think using ground effect is going to degrade performance in the scenario in question?
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I don’t have an opinion on that, as I’m not an aero engineer, nor have I tried the technique. That’s why I included both improvement and degradation in my statement.

Given the short flight distances involved from liftoff to 50 feet in most cases, I don’t think there would be a lot of difference either way.

And given the timing required to get it right (just clearing the obstacle without hitting it) I’d say that I understand why the manufacturers didn’t choose the technique.
 
Forget the regs for this.

You are planning a long cross country, and you are max gross weight limited. If you had 2 more hours of fuel, you could do it nonstop. Departure airport is cool, sea level, no obstructions, long runway and smooth air is forecast. Using Bonanza general max gross weight, I believe you would be around 5% over gross.

Which do you think has a greater chance of an accident? Taking off overweight or making the stop? Remember most accidents happen during landing, making the stop adds another.
 
MauleSkinner said:
I don’t have an opinion on that, as I’m not an aero engineer, nor have I tried the technique. That’s why I included both improvement and degradation in my statement.

Given the short flight distances involved from liftoff to 50 feet in most cases, I don’t think there would be a lot of difference either way.

And given the timing required to get it right (just clearing the obstacle without hitting it) I’d say that I understand why the manufacturers didn’t choose the technique.
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You should try it

It’s how I teach short and soft fields, but then have to preface with “for testing purposes” and also teach the OKC way of doing it.
 
decalogue said:
You should try it

It’s how I teach short and soft fields, but then have to preface with “for testing purposes” and also teach the OKC way of doing it.
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I generally choose to deal with obstacles that I can go under or around. :dunno:
 
decalogue said:
Respectfully disagree on that last part

Good book on this type of flying


“In the takeoff phase of every flight the main concern is getting airborne and rudder turning around or clearing any departure obstructions. With airplanes we have to consider the surface of the runway. Roughness in the first three hundred feet will slow our acceleration, but when we have accelerated to partial buoyancy, a rough section of the field might help bounce us off into ground effect flight.

It is a good habit to get off the surface (with flaps if we have them) and into low, level ground effect as soon as possible. Once off the surface and in ground effect, the remaining takeoff surface condition is of little consequence.

We should accelerate in low ground effect through stall speed, through Vx, through Vy, to a reasonable zoom reserve in the form of airspeed (we acquire this comfortable feeling through all our senses) prior to leaving low ground effect.

To leave ground effect sooner than absolutely necessary is unwise because of our poor engine power in comparison with the power of temperature, wind shear, humidity, density altitude, and gravity.
Natural laws have more power than our engine.”
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Show me data, not anecdote.
 
If you're gonna drain tanks, there are a ton of things you should do for safety.

1) Do it outside the hangar.
2) Ground the aircraft.
3) Bond the aircraft to your defueling gear.
4) Use metal containers and funnels if possible.
5) Don't do it on a cool dry day.

You don't wanna be the guy who starts a fire that burns down a row of hangars.
 
Plano Pilot said:
Forget the regs for this.

You are planning a long cross country, and you are max gross weight limited. If you had 2 more hours of fuel, you could do it nonstop. Departure airport is cool, sea level, no obstructions, long runway and smooth air is forecast. Using Bonanza general max gross weight, I believe you would be around 5% over gross.

Which do you think has a greater chance of an accident? Taking off overweight or making the stop? Remember most accidents happen during landing, making the stop adds another.
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Personally, I would make the fuel stop. My experience making over-gross takeoffs tells me not to do that again. And besides, at my age, I like to stretch my legs and visit the toilet after a few hours in the air. I am not at all concerned about the additional landing. I've made more than 5,000 uneventful landings, not even counting those I made during five years in the Air Force. And thousands more in the right seat guiding a student pilot.
 
kyleb said:
If you're gonna drain tanks, there are a ton of things you should do for safety.

1) Do it outside the hangar.
2) Ground the aircraft.
3) Bond the aircraft to your defueling gear.
4) Use metal containers and funnels if possible.
5) Don't do it on a cool dry day.

You don't wanna be the guy who starts a fire that burns down a row of hangars.
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fire extinguishers
 
kyleb said:
Show me data, not anecdote.
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I don’t really record all of that, but it’s pretty industry known for those who actually fly in short strips with trees etc

It’s also just common sense, building energy where you can and then transferring it.

Or just do the flight school thing and yank it off and immediately pitch for VX

Flying something like a champ in the warm months into fields champs were made for, grass and trees, you can use ground effect and climb over the trees on 65hp with relative ease, or try the get off the ground ASAP and try to have that A65 drag you over them. The ground effect methods is much less pucker factor
 
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dp342b said:
Would you still fly if your weight was over by 20 pounds? I know there's maximum gross weight and a maximum take off weight. In all reality, how far over is too much. I can understand 200 pounds overweight but 20 pounds? Hell I'd burn that off before top of climb.
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§ 91.9(a): “No person may operate a civil aircraft without complying with the operating limitations specified in the approved Airplane or Rotorcraft Flight Manual…”

20 lbs over is illegal operation, even 1 lbs over is too. Not sure you could even get a ferry permit but then if we are talking 20 lbs the FSDO may look at you funny too. Why couldn't this guy just remove a little fuel? Frankly, this is not a realistic discussion as it's obvious that a little less fuel is your only options - we are talking about 3.33 gallons!

The real question is, how would you calculate performance data? I know only 20 lbs but you wouldn't be able to by the POH limitations.

dp342b said:
Ya I plan on getting my CFI. Gotta get private and commercial first tho. Lol
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Asking this kind of question for what purpose? Entertainment? It's very illogical to say the absolute least. You should ask your CFI so the future CFI-you can tell your students.
 
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decalogue said:
Respectfully disagree on that last part

Good book on this type of flying


“In the takeoff phase of every flight the main concern is getting airborne and rudder turning around or clearing any departure obstructions. With airplanes we have to consider the surface of the runway. Roughness in the first three hundred feet will slow our acceleration, but when we have accelerated to partial buoyancy, a rough section of the field might help bounce us off into ground effect flight.

It is a good habit to get off the surface (with flaps if we have them) and into low, level ground effect as soon as possible. Once off the surface and in ground effect, the remaining takeoff surface condition is of little consequence.

We should accelerate in low ground effect through stall speed, through Vx, through Vy, to a reasonable zoom reserve in the form of airspeed (we acquire this comfortable feeling through all our senses) prior to leaving low ground effect.

To leave ground effect sooner than absolutely necessary is unwise because of our poor engine power in comparison with the power of temperature, wind shear, humidity, density altitude, and gravity.
Natural laws have more power than our engine.”
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Credibility was lost at “rudder turning.”
 
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