Four people in a Warrior II?
I think that my obvious answer to Pace's challenge is that I don't actually, 99/100 times, have to take off.
And to Jan's poser about microlight weights, is to look at the local accident statistics of these aeroplanes compared to light aeroplanes. You might also like to consider that LSAs in the USA are self-certified and do not have any competent authority oversight.
G
And to Jan's poser about microlight weights, is to look at the local accident statistics of these aeroplanes compared to light aeroplanes. You might also like to consider that LSAs in the USA are self-certified and do not have any competent authority oversight.
G
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I think most clever pilots know that Pace is right i.e. if the CofG is at/near the middle of the envelope then being overloaded just means needing a longer runway.
x% more weight means x% higher Vr and Vref and 2x% longer takeoff roll.
Otherwise, ferry pilots could not fly overloaded by up to 35% as they do.
The problem is that a lot of planes can be easily overloaded fore/aft of the envelope, simply by having people in the back seats. This is much worse for 6-seaters e.g. Seneca, Saratoga, etc. This is dangerous because there is no easy way to estimate the higher speeds required for a safe takeoff or landing, and more importantly the plane can give the illusion of being safely airborne when in fact there is insufficient elevator authority to safely continue the flight out of the ground effect.
The TB20 is quite unusual in that it is not practically possible to overload it fore/aft without exceeding the MTOW. I am constantly grateful for having chosen well (in ignorance, at the time) because it enables me to fill up to the brim every time.
x% more weight means x% higher Vr and Vref and 2x% longer takeoff roll.
Otherwise, ferry pilots could not fly overloaded by up to 35% as they do.
The problem is that a lot of planes can be easily overloaded fore/aft of the envelope, simply by having people in the back seats. This is much worse for 6-seaters e.g. Seneca, Saratoga, etc. This is dangerous because there is no easy way to estimate the higher speeds required for a safe takeoff or landing, and more importantly the plane can give the illusion of being safely airborne when in fact there is insufficient elevator authority to safely continue the flight out of the ground effect.
The TB20 is quite unusual in that it is not practically possible to overload it fore/aft without exceeding the MTOW. I am constantly grateful for having chosen well (in ignorance, at the time) because it enables me to fill up to the brim every time.
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GenghisJust the man a question for you? Given standard temps and sea level how much overweight will an aircraft takeoff presuming the C of G is ok and off an unlimited lenghth runway?
I have known tanked up ferry twins takeoff 600 ibs or more over grosse. Obviously engine out means earthbound in such a twin but they do fly!
Prob get shot to pieces
ferried a jet to S Africa and had to depart a military base in Africa for an island called Sao Tome 500 miles off the Nigerian coastline and near the limits of range.The airfield was 12000 feet long but 4600 feet AMSL and temp was plus 30 at that altitude, full fuel (needed) There was nothing in the manuals to match.
Rotated plus 20 Kts after using a lot of runway and flew off like a bird. (of course all made up
in fact there is insufficient elevator authority to safely continue the flight out of the ground effect.
Pace
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Friend of mine had a Cessna 180 on Floats, kept it on his dock by his home in Louisiana, on a bayou. He was well experienced, commercial pilot, and ran a business taking replacement crews out to the oil rigs in the Gulf of Mexico....
I watched him loading up two checkered shirt chaps, with their sleeping bags, weather gear, baseball caps, cases of beer, snacks, food, shotguns, ammunition, etc etc....and they were all 3 of them standard USA overweight....
But he knew what he was doing. Didn't matter how much he loaded up that Cessna, the takeoff on the bayou was quite simple, just went on round the bend, and around the next bend and the next bend until enough fuel had been used up and it took off.....
I watched him loading up two checkered shirt chaps, with their sleeping bags, weather gear, baseball caps, cases of beer, snacks, food, shotguns, ammunition, etc etc....and they were all 3 of them standard USA overweight....
But he knew what he was doing. Didn't matter how much he loaded up that Cessna, the takeoff on the bayou was quite simple, just went on round the bend, and around the next bend and the next bend until enough fuel had been used up and it took off.....
Genghis
Just the man a question for you? Given standard temps and sea level how much overweight will an aircraft takeoff presuming the C of G is ok and off an unlimited lenghth runway?
Just the man a question for you? Given standard temps and sea level how much overweight will an aircraft takeoff presuming the C of G is ok and off an unlimited lenghth runway?
You are of-course right that CG is usually more critical (I've flown aeroplanes out of CG, how else could we work out the CG limits in the first place!), but the fact is that the numbers are there and go beyond them and you are in territory that will always be, to some extent, unknown.
If you know the aeroplane well enough, and don't care about the insurance.....
G
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You are of-course right that CG is usually more critical (I've flown aeroplanes out of CG, how else could we work out the CG limits in the first place!),
How do you work out the max takeoff weight (In the first place ?)
Pace
MTOW is generally the weight at which the main structural (wing, tail, undercarriage) structural requirements are only just met. Typically this is in the order of 3.8g +Ve, -1.9g -Ve, 3g landing, Vd/fwd-CG/tailplane-loads: but the numbers are a lot more complex than that. The safety margins applied to those numbers depend upon construction methods, but for an all metal aeroplane, it'll be around 1.5.
There's usually some additional performance requirements particularly for twins or very underpowered microlights and motorgliders. However, in most cases there's a surplus of power so the MTOW dictates the performance numbers, rather than the other way around.
Fwd CG is dictated usually either by some measure of adequate controllability - the critical case is usually the (ability to) flare, or by tailplane attachment strength. Aft CG is dictated by a collection of controllability issues including spin resistance or recovery, stall characteristics, static directional stability, or pitch control forces. All of this takes quite a lot of time in flight test to get right.
In reality, the aeroplane is usually designed to a desired (or required by regulations) MTOW, and everything else made to fit it.
G
There's usually some additional performance requirements particularly for twins or very underpowered microlights and motorgliders. However, in most cases there's a surplus of power so the MTOW dictates the performance numbers, rather than the other way around.
Fwd CG is dictated usually either by some measure of adequate controllability - the critical case is usually the (ability to) flare, or by tailplane attachment strength. Aft CG is dictated by a collection of controllability issues including spin resistance or recovery, stall characteristics, static directional stability, or pitch control forces. All of this takes quite a lot of time in flight test to get right.
In reality, the aeroplane is usually designed to a desired (or required by regulations) MTOW, and everything else made to fit it.
G
Just did the sample calculation for one of our PA28s. It's a PA28-161 Cadet.
Empty weight 1465 lbs
Four FAA standard adults 4x170 = 680 lbs
30 USG fuel = 180 lbs
Total weight = 2325 lbs
Max weight = 2332 lbs. 7 lbs left over, and this situation is well within the CofG envelope. 30 USG is about 3.5 hours till empty tanks.
Filling to the tabs is actually 34 USG, formally, but I doubt whether anyone can fill to those tabs with +/- 1 USG accuracy. But anyway, with 34 USG fuel you will be 13 lbs overweight.
Empty weight 1465 lbs
Four FAA standard adults 4x170 = 680 lbs
30 USG fuel = 180 lbs
Total weight = 2325 lbs
Max weight = 2332 lbs. 7 lbs left over, and this situation is well within the CofG envelope. 30 USG is about 3.5 hours till empty tanks.
Filling to the tabs is actually 34 USG, formally, but I doubt whether anyone can fill to those tabs with +/- 1 USG accuracy. But anyway, with 34 USG fuel you will be 13 lbs overweight.
Folklore has it that 3 is OK with full fuel and 4 OK with tabs. Not true. As pointed out earlier the difference in fuel actually only accounts for approx 70lbs
Monkey..I suggest you see your Flying Club and go thru the actual figures, for the subject aircraft with them, rather than relying on information from here!
Moderator
I have condoned flying overweight, when it's done in accordance with an approval. It can be done, but somewhere, you are sacrificing a safety characteristic. If you reconize where you're making that sacrifice, and compensate, it can work. That's why we find an APPROVED way to do it! For example, Cessna will tell you right in the Type Certificate Data Sheet for a few of their models how to do it.
In most cases, however, the gross weight limit for any given aircraft is a product of what it was able to demonstrated at the point of reaching one of many certification limits - there are many.
When I think back on how aircraft have been presented to me for design approval flight test, the most common failing in preparation was the weight and balance. Therefore, if it is at all critical for the flight, I witness the weighing of the aircraft, and do the math myself.
I could go on and on here with the errors I have found in test subject aircraft, and aircraft at large. I can't type that much!
A few scary highlights:
A 8700 pound GW aircraft presented to me for flight test, with a fresh W&B by weighing. Everything within limits, but I noticed that the measured weight on the right wheel was 280 pounds more than that of the left. "why?" I asked. No good answer (fuel and all variables were as they should be). Weigh it again... They did, and the numbers were all completely different. I then had three more weighings done, saw the new numbers were close and averaged them. (I wanted it right, I was spinning this aircraft at GW, both C of G limits).
After test flying spin testing a modified C 185, which was ballasted to the aft limit at GW, (it was compliant but poor to fly). I complained the something was wrong, new W&B calculated, the aircraft had been several inches behind the aft limit for my test! I should have caught that before flying!
A client calls for removal of a float installation limitation on a Stinson, which prohibits back seat occupancy. I ask for the the weight and balance for the float equipped aircraft. I do the math. As is, with two front seat occupants, this aircraft is nearly never flown within the C of G range, it's always out aft (the most dangerous side).
and worst, back in my early days, I regularly flew freight in the owner's 182. He loaded, I flew - 6 hours each way. I departed a 1600' turf strip. The one morning he says "Fly 'er careful, she's real heavy today...". Okay, and off I go. Yep it felt heavy! I was very gentle and cautious for the whole flight. When I reached my destination, I tallied what I unloaded. I had been more than 800 pounds overgross on takeoff!
Pace and IO are right, in the real world, planes fly overgross some times. Those two fat guys in the 152 are a perfect, and all too common, example. Planning to do it without the legally required approvals, exposes you to all kinds of safety concerns and penaties. Can you look your passenger in the eye, and say "I'm about to fly you in an aircraft which is overweight and not approved"? No one's going to get you for being accidentally 30 pounds over, but that extra person is a very bad idea!
Yes, I once sent a pilot to fly circles for an hour, to get a Caravan back to the weight it needed to be to begin our testing.
In most cases, however, the gross weight limit for any given aircraft is a product of what it was able to demonstrated at the point of reaching one of many certification limits - there are many.
When I think back on how aircraft have been presented to me for design approval flight test, the most common failing in preparation was the weight and balance. Therefore, if it is at all critical for the flight, I witness the weighing of the aircraft, and do the math myself.
I could go on and on here with the errors I have found in test subject aircraft, and aircraft at large. I can't type that much!
A few scary highlights:
A 8700 pound GW aircraft presented to me for flight test, with a fresh W&B by weighing. Everything within limits, but I noticed that the measured weight on the right wheel was 280 pounds more than that of the left. "why?" I asked. No good answer (fuel and all variables were as they should be). Weigh it again... They did, and the numbers were all completely different. I then had three more weighings done, saw the new numbers were close and averaged them. (I wanted it right, I was spinning this aircraft at GW, both C of G limits).
After test flying spin testing a modified C 185, which was ballasted to the aft limit at GW, (it was compliant but poor to fly). I complained the something was wrong, new W&B calculated, the aircraft had been several inches behind the aft limit for my test! I should have caught that before flying!
A client calls for removal of a float installation limitation on a Stinson, which prohibits back seat occupancy. I ask for the the weight and balance for the float equipped aircraft. I do the math. As is, with two front seat occupants, this aircraft is nearly never flown within the C of G range, it's always out aft (the most dangerous side).
and worst, back in my early days, I regularly flew freight in the owner's 182. He loaded, I flew - 6 hours each way. I departed a 1600' turf strip. The one morning he says "Fly 'er careful, she's real heavy today...". Okay, and off I go. Yep it felt heavy! I was very gentle and cautious for the whole flight. When I reached my destination, I tallied what I unloaded. I had been more than 800 pounds overgross on takeoff!
Pace and IO are right, in the real world, planes fly overgross some times. Those two fat guys in the 152 are a perfect, and all too common, example. Planning to do it without the legally required approvals, exposes you to all kinds of safety concerns and penaties. Can you look your passenger in the eye, and say "I'm about to fly you in an aircraft which is overweight and not approved"? No one's going to get you for being accidentally 30 pounds over, but that extra person is a very bad idea!
Yes, I once sent a pilot to fly circles for an hour, to get a Caravan back to the weight it needed to be to begin our testing.
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On a long runway would you rather takeoff slightly overweight but in C of G with more fuel at destination or at correct weight but just on required fuel at destination?
Quick replan and either stop for gas on the way, reduce the load, change the destination or cancel the flight.
Like you, I've seen 152's stagger into the air overweight, I quit a flying school with such a attitude and found a decent one.
If one thinks it through, in a logical and rational manner, by flying overweight (as commander) you are invalidating your insurance in the event of an incident, making yourself a criminal if there is a bang and the authorities decide to prosecute and possibly disinheriting your family - think Graham Hill.
Yep, 99/100 you'll get away with it, but the day you don't, the investigation team will quickly find out and you'll have the rest of your life to regret it.
I understand, Pace, that you are a commercial pilot and face different pressures. I don't have the training or experience or necessity to make some of the decisions that you face everyday.
Back to the original questions. 4 up in a -161 is going to be margnal at the best, do the W&B very carefully and if you are legal, monitor the take off roll like a hawk and have a clear decision point in your mind, so you stop if you are not happy with the acceleration or feel of the aircraft.
Even if the book says you are okay, a 'tired' engine and hangar rash can impact performance and there is no shame in rejecting a takeoff, because it didn't feel right - I know, I've done it in a PA28 4 up (with 2 adults, over 8st adult and a child.)
Also, be very clear about EFATO options, as the glide performance will feel different to normal.
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Backpacker...I think something has gone seriously wrong there!
Folklore has it that 3 is OK with full fuel and 4 OK with tabs. Not true. As pointed out earlier the difference in fuel actually only accounts for approx 70lbs
Folklore has it that 3 is OK with full fuel and 4 OK with tabs. Not true. As pointed out earlier the difference in fuel actually only accounts for approx 70lbs
Empty weight 1465 lbs
3 FAA standard adults 510 lbs
48 USG fuel 288 lbs
Total 2263 lbs
MTOW 2332 lbs
So there's a healthy 69 lbs left over!
Furthermore, the difference between the tabs (34 USG) and full (48 USG) is actually 84 lbs, not 70 lbs.
Take that 69 lbs left over in the 3-adult configuration, add the fuel difference of 84 lbs and you have 153 lbs to play with. That's *almost* another adult.
I'm not making this up. These are the actual numbers, in this case for a PA28-161 Cadet. I can give you the moments and arms as well but I'm too lazy to start typing those in. But they all fall well within the limits.
But having said that, of course not all aircraft are equal and there seems to be a lot of variation within the PA28-161 range. Not just empty weight but also MTOW (Cadet vs. Warrior III for instance). And not all adults are FAA average. So the numbers may indeed work out differently for your aircraft.
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I would be interested to learn what ferry pilots do with CG.
If I understand the moments right, with say a 100 inch arm to the tailplane, then every inch of aft CG gives roughly 1% extra lift (less downforce on the tailplane). So there is a stability / fuel load trade-off.
Not one I have any appetite for, but I'm no ferry pilot.
If I understand the moments right, with say a 100 inch arm to the tailplane, then every inch of aft CG gives roughly 1% extra lift (less downforce on the tailplane). So there is a stability / fuel load trade-off.
Not one I have any appetite for, but I'm no ferry pilot.
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I remember my PPL skills test many moons ago...
Myself at 6'3", 15st and my examiner of a similar height and even greater weight squeezed ourselves into a C152.
Examiner asks if i've done the W&B for the flight, "Yes" I reply, "What does it say?" he asks..."We're well out of the forward CG limit and xxxlbs over MTOW"
"Thats fine, as long as your aware of it, carry on...." and off we went for our flight.....
Myself at 6'3", 15st and my examiner of a similar height and even greater weight squeezed ourselves into a C152.
Examiner asks if i've done the W&B for the flight, "Yes" I reply, "What does it say?" he asks..."We're well out of the forward CG limit and xxxlbs over MTOW"
"Thats fine, as long as your aware of it, carry on...." and off we went for our flight.....
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As a former freightdog, I often had to resist pressure from management pushing me to load extra and fly overweight. I will tell you what I told them - The question is not how much can we overload and still heave the aircraft off the runway. The question is what will happen if an engine fails, and can we survive, and hopefully not have to drop the aircraft into the houses off the departure end of the runway. As a pilot, your responsibility goes beyond just yourself. Crash into a house, bad pilot.
Yes, a properly functioning aircraft can certainly lift off overweight. Every time you fly a 45 degree bank, you are producing lift suffienct to support 1.5 of the aircraft weight. If you do take off overweight, be sure you don't "crank and bank". Not a good time to be hotdogging and showing off your maneuvering skills! Remember, all your V speeds are no longer valid overweight. For instance stall speed will be higher. What is the new stall speed? Who knows - you are now a test pilot. Just don't do it, but if you do, avoid flying in turbulence, keep your banks shallow, and make sure you have plenty of runway.
Yes, a properly functioning aircraft can certainly lift off overweight. Every time you fly a 45 degree bank, you are producing lift suffienct to support 1.5 of the aircraft weight. If you do take off overweight, be sure you don't "crank and bank". Not a good time to be hotdogging and showing off your maneuvering skills! Remember, all your V speeds are no longer valid overweight. For instance stall speed will be higher. What is the new stall speed? Who knows - you are now a test pilot. Just don't do it, but if you do, avoid flying in turbulence, keep your banks shallow, and make sure you have plenty of runway.
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24carrot
C of G is an absolute No No if it's out of limits and a very scary situation to be in.
Several years ago I took a businessman an engineer to Cork 50 times in the course of the year.
Normal trip he turned up with two others and light baggage.
All three were lightweight.
Fueled the Seneca five and ran off to the Loo leaving them chatting.
Came back and we all jumped in ready to go.
Two sat on the back club seats the other on one of the forward seats facing back.
I took off and the aircraft was almost unflyible
There was little elevator authority and the nose was trying to pitch up and down.
I flew level to build speed and called for both rear pax to move as far to the front as possible.
I did a gentle circuit and landed 10 kts above the normal landing speed.
The engineer owner had at the last minute decided to remove a heavy metal tool box and loaded it in the aft weight limited baggage compartment.
He dropped his coat on top and had done this when I had gone to the Loo without telling me.
I could hardly lift it out.
So don't mess with C of G
Pace
C of G is an absolute No No if it's out of limits and a very scary situation to be in.
Several years ago I took a businessman an engineer to Cork 50 times in the course of the year.
Normal trip he turned up with two others and light baggage.
All three were lightweight.
Fueled the Seneca five and ran off to the Loo leaving them chatting.
Came back and we all jumped in ready to go.
Two sat on the back club seats the other on one of the forward seats facing back.
I took off and the aircraft was almost unflyible
There was little elevator authority and the nose was trying to pitch up and down.
I flew level to build speed and called for both rear pax to move as far to the front as possible.
I did a gentle circuit and landed 10 kts above the normal landing speed.
The engineer owner had at the last minute decided to remove a heavy metal tool box and loaded it in the aft weight limited baggage compartment.
He dropped his coat on top and had done this when I had gone to the Loo without telling me.
I could hardly lift it out.
So don't mess with C of G
Pace
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24carrot
C of G is an absolute No No if it's out of limits and a very scary situation to be in.
...
So don't mess with C of G
Pace
C of G is an absolute No No if it's out of limits and a very scary situation to be in.
...
So don't mess with C of G
Pace
But since ferry pilots are apparently breaking the weight limits, I was curious about where they put the CG. Mid point, max aft, three-quarters?
But then, where is 'max aft' if you are overweight? So presumably they should put it in the middle as that is the only position that they can still trust.
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Ferry pilots normally fly alone, and those who fly with a ferry tank (note: most reasonable IFR planes don't need a ferry tank to do the USA-UK route via Greenland, Iceland, etc, or indeed anywhere else in the world except places like perhaps Australia) they have a ferry tank on the back seats.
Sometimes, like in one case of a TB20 currently flying USA-Australia over the Pacific, they remove the back seats and ship them as freight.
So the extra weight ends up more or less in the middle of the envelope.
Sometimes, like in one case of a TB20 currently flying USA-Australia over the Pacific, they remove the back seats and ship them as freight.
So the extra weight ends up more or less in the middle of the envelope.
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This Cessna 172 FlightAware > N9086Y C172
was grossly over weight when it left St John's early today.
It has an FAA approved ferry tank and been certified for this flight.
They use lots of runway and rotation is usually +20 knot's with a shallow climb out.
was grossly over weight when it left St John's early today.
It has an FAA approved ferry tank and been certified for this flight.
They use lots of runway and rotation is usually +20 knot's with a shallow climb out.
One point, one question (which is also really a point):-
Point: Ferry flights are done by very experienced pilots, who have done calculations to confirm acceptability of risk, and factor aircraft performance. They are not carrying passengers, they are carrying special insurance.
Question: Does anybody here weigh the FAA "standard" adult weight that keeps being quoted of 170lb / 12st 2/ 77kg, or less ? How about your regular passengers?
G
Point: Ferry flights are done by very experienced pilots, who have done calculations to confirm acceptability of risk, and factor aircraft performance. They are not carrying passengers, they are carrying special insurance.
Question: Does anybody here weigh the FAA "standard" adult weight that keeps being quoted of 170lb / 12st 2/ 77kg, or less ? How about your regular passengers?
G
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24Carrot
My best friend and almost like a second father to me was killed ferrying a 172 18 months back.
He was a wonderful guy and at the age of 78 was still ferrying singles across the pond at all times of year.
I know in his situation with the ferry tank full the aircraft was right at the back of the envelope regarding C of G and heavy.
Not the best situation at best of times but not a good sitution mid winter with icing around.
As I have stated I am not suggesting pilots especially inexperienced ones fly overweight.
I tried to broaden the discussion into an area which I know does happen a lot in GA.
There is a difference between being slightly overweight and as pilot DAR stated being 800 ibs over grosse.
On the right runway with my destinations both clear but something I dont like in the weather scenario will I go at MAX with legal fuel reserves or put in a few extra gals just incase????
Pace
My best friend and almost like a second father to me was killed ferrying a 172 18 months back.
He was a wonderful guy and at the age of 78 was still ferrying singles across the pond at all times of year.
I know in his situation with the ferry tank full the aircraft was right at the back of the envelope regarding C of G and heavy.
Not the best situation at best of times but not a good sitution mid winter with icing around.
As I have stated I am not suggesting pilots especially inexperienced ones fly overweight.
I tried to broaden the discussion into an area which I know does happen a lot in GA.
There is a difference between being slightly overweight and as pilot DAR stated being 800 ibs over grosse.
On the right runway with my destinations both clear but something I dont like in the weather scenario will I go at MAX with legal fuel reserves or put in a few extra gals just incase????
Pace