WACO YMF
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RE: WACO YMF
Jaybird,
I fly full scale as well. Much better than RC planes. Never wrecked one yet. I brought this up because I thought the subject has been ignored by the model side. Just balancing it isn't enough in my view. I would really like to know the theoretical approach needed to get the answers. Beside me is a text by Barnes McCormick,who was a prof at Penn State and a world class expert on Aerodynamics. I'm not about to grind through all of that, but would like a more simplified answer appropriate to RC planes.
I fly full scale as well. Much better than RC planes. Never wrecked one yet. I brought this up because I thought the subject has been ignored by the model side. Just balancing it isn't enough in my view. I would really like to know the theoretical approach needed to get the answers. Beside me is a text by Barnes McCormick,who was a prof at Penn State and a world class expert on Aerodynamics. I'm not about to grind through all of that, but would like a more simplified answer appropriate to RC planes.
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RE: WACO YMF
Sorry, didn't mean to preach to the chior.
I agree 100%...the model side of aerodynamics seems more of a mystery than full scale. I look at a big Telemaster for instance and notice that the stabilizer is a large flat bottom UPRIGHT airfoil just like the wing! How can that NOT produce upward lift all the time? I look at my 1/6 scale Concept Fleet and the stabilizer is also a flat bottom upright airfoil with positive incidence. That kind of puts the tail downforce out the window too, or at least would seem so.
Calculating the information you are looking for is far beyond anything I could get even get close to.
I do know the GP WACO ARF has -1 incidence on the top wing and +2-1/2 on the symetrically shaped stabilzer and it flies great!
Good luck on your search. If you do find a answer please share it.
Jaybird
I agree 100%...the model side of aerodynamics seems more of a mystery than full scale. I look at a big Telemaster for instance and notice that the stabilizer is a large flat bottom UPRIGHT airfoil just like the wing! How can that NOT produce upward lift all the time? I look at my 1/6 scale Concept Fleet and the stabilizer is also a flat bottom upright airfoil with positive incidence. That kind of puts the tail downforce out the window too, or at least would seem so.
Calculating the information you are looking for is far beyond anything I could get even get close to.
I do know the GP WACO ARF has -1 incidence on the top wing and +2-1/2 on the symetrically shaped stabilzer and it flies great!
Good luck on your search. If you do find a answer please share it.
Jaybird
RE: WACO YMF
ORIGINAL: Jaybird
Sorry, didn't mean to preach to the chior.
I agree 100%...the model side of aerodynamics seems more of a mystery than full scale. I look at a big Telemaster for instance and notice that the stabilizer is a large flat bottom UPRIGHT airfoil just like the wing! How can that NOT produce upward lift all the time? I look at my 1/6 scale Concept Fleet and the stabilizer is also a flat bottom upright airfoil with positive incidence. That kind of puts the tail downforce out the window too, or at least would seem so.
Calculating the information you are looking for is far beyond anything I could get even get close to.
I do know the GP WACO ARF has -1 incidence on the top wing and +2-1/2 on the symetrically shaped stabilzer and it flies great!
Good luck on your search. If you do find a answer please share it.
Jaybird
Sorry, didn't mean to preach to the chior.
I agree 100%...the model side of aerodynamics seems more of a mystery than full scale. I look at a big Telemaster for instance and notice that the stabilizer is a large flat bottom UPRIGHT airfoil just like the wing! How can that NOT produce upward lift all the time? I look at my 1/6 scale Concept Fleet and the stabilizer is also a flat bottom upright airfoil with positive incidence. That kind of puts the tail downforce out the window too, or at least would seem so.
Calculating the information you are looking for is far beyond anything I could get even get close to.
I do know the GP WACO ARF has -1 incidence on the top wing and +2-1/2 on the symetrically shaped stabilzer and it flies great!
Good luck on your search. If you do find a answer please share it.
Jaybird
Bob
Thread Starter
RE: WACO YMF
The issue that we get into have to do with Reynold Numbers. Full Scale airplanes differ from models due to the effects of Scale Volume, not Linear scale. The bigger the model, the more like the full scale it becomes. For example, a cube that is 4"X4"X4" will have a volume of 64 cubic inches. (4X4=16X4=64) A quarter scale model of that cube is 1X1X1 which yields a volume of 1. Even though the linear scale is one fourth the size of the full scale, the volume is much different. Hope this helps you see the difference.
Bill, Waco Brother #1
Bill, Waco Brother #1
RE: WACO YMF
ORIGINAL: Stickbuilder
The issue that we get into have to do with Reynold Numbers. Full Scale airplanes differ from models due to the effects of Scale Volume, not Linear scale. The bigger the model, the more like the full scale it becomes. For example, a cube that is 4''X4''X4'' will have a volume of 64 cubic inches. (4X4=16X4=64) A quarter scale model of that cube is 1X1X1 which yields a volume of 1. Even though the linear scale is one fourth the size of the full scale, the volume is much different. Hope this helps you see the difference.
Bill, Waco Brother #1
The issue that we get into have to do with Reynold Numbers. Full Scale airplanes differ from models due to the effects of Scale Volume, not Linear scale. The bigger the model, the more like the full scale it becomes. For example, a cube that is 4''X4''X4'' will have a volume of 64 cubic inches. (4X4=16X4=64) A quarter scale model of that cube is 1X1X1 which yields a volume of 1. Even though the linear scale is one fourth the size of the full scale, the volume is much different. Hope this helps you see the difference.
Bill, Waco Brother #1
Bob
RE: WACO YMF
This is a very interesting discussion. One thing does not change. The wing has to fly at an angle of attack (AOA) at any given speed that will allow it (the wing) to produce enough lift to support the weight of the aircraft..If the plane appears to be "dragging it's tail", but still maintinaing altitude, then lift vs weight (gravity) is balanced. The plane is either too slow, too heavy, or the wing is mounted at the wrong incidence angle on the fuse. What ever is going on with the stab/elevator is just what is neccesary to maintain that AOA.
IF the aircraft is tail heavy, You just can't trim it out to fly in a stable mannor; ie, hands off. I was a commercial pilot, and on a charter flight Idid early on in my carrier, I flew a load of water bottles to a lab to be analyzed for a new treatment plant. I was in a Cessna 206. All of the seatswere taken out and the bottles, about ten gallons each, were spread out on the floor and strapped down with a cargo net. As soon as Ibroke ground, the nose pitched up. I went forward on the elevator, and it pitched down. This continued all the way for the 300 mile flight. Ipulledmy seat as far forward as possible, but it was not enough. I was afraid I would not be able to land as the oscillations continued all the way to touchdown. We had all assumed we would be OKwith the CG. Wrong,
As for the lifting tails on some models, Guess what? Some models are designed with a very aft CG.Competation free flight models ,YES, often have aCG back around 50 to 60 percent of MAC, but they all have stabs that are a large percentage of the total area., and they produce lift.The idea is that it's more effecient to have all of the flight surfaces contributing to overall lift, rather than having the tail exererting a down force
Iknow, this has not helped this discussion, but only muddied the water. It sure seems to me that a positive incidence on the stab (LEup), would seem to indicate a slightly aft CGby design. The large tail plane would seem to support that.
Joe
IF the aircraft is tail heavy, You just can't trim it out to fly in a stable mannor; ie, hands off. I was a commercial pilot, and on a charter flight Idid early on in my carrier, I flew a load of water bottles to a lab to be analyzed for a new treatment plant. I was in a Cessna 206. All of the seatswere taken out and the bottles, about ten gallons each, were spread out on the floor and strapped down with a cargo net. As soon as Ibroke ground, the nose pitched up. I went forward on the elevator, and it pitched down. This continued all the way for the 300 mile flight. Ipulledmy seat as far forward as possible, but it was not enough. I was afraid I would not be able to land as the oscillations continued all the way to touchdown. We had all assumed we would be OKwith the CG. Wrong,
As for the lifting tails on some models, Guess what? Some models are designed with a very aft CG.Competation free flight models ,YES, often have aCG back around 50 to 60 percent of MAC, but they all have stabs that are a large percentage of the total area., and they produce lift.The idea is that it's more effecient to have all of the flight surfaces contributing to overall lift, rather than having the tail exererting a down force
Iknow, this has not helped this discussion, but only muddied the water. It sure seems to me that a positive incidence on the stab (LEup), would seem to indicate a slightly aft CGby design. The large tail plane would seem to support that.
Joe
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RE: WACO YMF
ORIGINAL: sensei
This is actually a good point to bring up, for the very reason that the effects of scale volume are not linear. The larger an airframe, the more efficiently it will carry weight, that is why lets say a full scale Extra 300 weighing in at around 1400 lbs. empty performs very well at that weight. Now take a half scale Extra 300 and weigh it down 700 lbs. and it is not going anyplace, in fact at half scale weighing it down to 100 lbs. and it is a real pig. Now lets get down to small aircraft anything 1/4 scale or less. The smaller the airplane the more important it is to build as light as possible, because the Reynolds numbers are working against you from a load carrying efficiency standpoint.
Bob
ORIGINAL: Stickbuilder
The issue that we get into have to do with Reynold Numbers. Full Scale airplanes differ from models due to the effects of Scale Volume, not Linear scale. The bigger the model, the more like the full scale it becomes. For example, a cube that is 4''X4''X4'' will have a volume of 64 cubic inches. (4X4=16X4=64) A quarter scale model of that cube is 1X1X1 which yields a volume of 1. Even though the linear scale is one fourth the size of the full scale, the volume is much different. Hope this helps you see the difference.
Bill, Waco Brother #1
The issue that we get into have to do with Reynold Numbers. Full Scale airplanes differ from models due to the effects of Scale Volume, not Linear scale. The bigger the model, the more like the full scale it becomes. For example, a cube that is 4''X4''X4'' will have a volume of 64 cubic inches. (4X4=16X4=64) A quarter scale model of that cube is 1X1X1 which yields a volume of 1. Even though the linear scale is one fourth the size of the full scale, the volume is much different. Hope this helps you see the difference.
Bill, Waco Brother #1
Bob
Banned
RE: WACO YMF
" The wing has to fly at an angle of attack (AOA) at any given speed that will allow it (the wing) to produce enough lift to support the weight of the aircraft"
Only for symmetrical airfoils.
Les
Only for symmetrical airfoils.
Les
RE: WACO YMF
ORIGINAL: peterduplessis
Using your example of the Extra 300 weighing 1400 lbs (power to weight ratio of 0.2143)... a third scale would theoretically be 1/27th (3x3x3) =51 lbs .. (mm a little heavy on the wing loading!) with 11hp (300hp/27) same power to weight ratio... will fly probably quite realistically compared to the full size in terms of take-off and stall speed performance. As modellers, Have we not just become more accustomed to having more power to weight (that 1/3rd scale Extra would typically weigh around 30-35 lbs) to get the adrenalin pumping? Peter, #224
ORIGINAL: sensei
This is actually a good point to bring up, for the very reason that the effects of scale volume are not linear. The larger an airframe, the more efficiently it will carry weight, that is why lets say a full scale Extra 300 weighing in at around 1400 lbs. empty performs very well at that weight. Now take a half scale Extra 300 and weigh it down 700 lbs. and it is not going anyplace, in fact at half scale weighing it down to 100 lbs. and it is a real pig. Now lets get down to small aircraft anything 1/4 scale or less. The smaller the airplane the more important it is to build as light as possible, because the Reynolds numbers are working against you from a load carrying efficiency standpoint.
Bob
ORIGINAL: Stickbuilder
The issue that we get into have to do with Reynold Numbers. Full Scale airplanes differ from models due to the effects of Scale Volume, not Linear scale. The bigger the model, the more like the full scale it becomes. For example, a cube that is 4''X4''X4'' will have a volume of 64 cubic inches. (4X4=16X4=64) A quarter scale model of that cube is 1X1X1 which yields a volume of 1. Even though the linear scale is one fourth the size of the full scale, the volume is much different. Hope this helps you see the difference.
Bill, Waco Brother #1
The issue that we get into have to do with Reynold Numbers. Full Scale airplanes differ from models due to the effects of Scale Volume, not Linear scale. The bigger the model, the more like the full scale it becomes. For example, a cube that is 4''X4''X4'' will have a volume of 64 cubic inches. (4X4=16X4=64) A quarter scale model of that cube is 1X1X1 which yields a volume of 1. Even though the linear scale is one fourth the size of the full scale, the volume is much different. Hope this helps you see the difference.
Bill, Waco Brother #1
Bob
Bob
RE: WACO YMF
ORIGINAL: LesUyeda
'' The wing has to fly at an angle of attack (AOA) at any given speed that will allow it (the wing) to produce enough lift to support the weight of the aircraft''
Only for symmetrical airfoils.
Les
'' The wing has to fly at an angle of attack (AOA) at any given speed that will allow it (the wing) to produce enough lift to support the weight of the aircraft''
Only for symmetrical airfoils.
Les
Bob
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RE: WACO YMF
Don't all airfoils need some AOA to the relative wind to produce lift?
AOA (angle of Attack) happens during flight in relationship to the relative wind and is different than AOI (Angle of Incidence) which part of the structural design.
What was the question again?
Jaybird
AOA (angle of Attack) happens during flight in relationship to the relative wind and is different than AOI (Angle of Incidence) which part of the structural design.
What was the question again?
Jaybird
RE: WACO YMF
ORIGINAL: Jaybird
Don't all airfoils need some AOA to the relative wind to produce lift?
AOA (angle of Attack) happens during flight in relationship to the relative wind and is different than AOI (Angle of Incidence) which part of the structural design.
What was the question again?
Jaybird
Don't all airfoils need some AOA to the relative wind to produce lift?
AOA (angle of Attack) happens during flight in relationship to the relative wind and is different than AOI (Angle of Incidence) which part of the structural design.
What was the question again?
Jaybird
Bob
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RE: WACO YMF
Who is this guy Reynolds??? Why did he screw everything up??? Lift generation??
According to the Bernoulli venturi principle it's the "separation of air molecules" allowing a low pressure area on the top surface of the wing????? That's what I taught when I was a certificated flight instructor....how many years ago was that???
Just kidding around. The whole basic aerodynamics discussion is fun. Mitch
According to the Bernoulli venturi principle it's the "separation of air molecules" allowing a low pressure area on the top surface of the wing????? That's what I taught when I was a certificated flight instructor....how many years ago was that???
Just kidding around. The whole basic aerodynamics discussion is fun. Mitch
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RE: WACO YMF
Hi Joe,
symmetrical airfoil was chosen to have a better inverted flight performance. If you fly upside down with Clark Y your AoA has to be awfully high which in my opinion does not look nice. With the symmetrical airfoil you AoA is much lower and your nearly can fly straight and level. That was the reason for this airfoil. A customer did built it with the Clark Y flies good as well but inverted see above.
Peter
Waco Brother #170
symmetrical airfoil was chosen to have a better inverted flight performance. If you fly upside down with Clark Y your AoA has to be awfully high which in my opinion does not look nice. With the symmetrical airfoil you AoA is much lower and your nearly can fly straight and level. That was the reason for this airfoil. A customer did built it with the Clark Y flies good as well but inverted see above.
Peter
Waco Brother #170
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RE: WACO YMF
Barry,
sorry fro not mentioning the CG in the plans but the CG is max. 2 cm in front of the aft cabane struts on the upper wing center section if you weight it in more to the front it is nose heavy which is not such as critical as tail heavy but....
Peter Waco brother #170
sorry fro not mentioning the CG in the plans but the CG is max. 2 cm in front of the aft cabane struts on the upper wing center section if you weight it in more to the front it is nose heavy which is not such as critical as tail heavy but....
Peter Waco brother #170
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RE: WACO YMF
To All,
just to make it clear:
upper wing 0 to minus 2 degrees
lower wing 0 degrees
horizontal stab 2 degrees leading edge up
CG just in front of the aft cabane strut about one to two fingers width.
That's how the Barth Wacos should fly and I do fly them.
Peter
Waco brother #170
just to make it clear:
upper wing 0 to minus 2 degrees
lower wing 0 degrees
horizontal stab 2 degrees leading edge up
CG just in front of the aft cabane strut about one to two fingers width.
That's how the Barth Wacos should fly and I do fly them.
Peter
Waco brother #170
RE: WACO YMF
ORIGINAL: FMBB
Hi Joe,
symmetrical airfoil was chosen to have a better inverted flight performance. If you fly upside down with Clark Y your AoA has to be awfully high which in my opinion does not look nice. With the symmetrical airfoil you AoA is much lower and your nearly can fly straight and level. That was the reason for this airfoil. A customer did built it with the Clark Y flies good as well but inverted see above.
Peter
Waco Brother #170
Hi Joe,
symmetrical airfoil was chosen to have a better inverted flight performance. If you fly upside down with Clark Y your AoA has to be awfully high which in my opinion does not look nice. With the symmetrical airfoil you AoA is much lower and your nearly can fly straight and level. That was the reason for this airfoil. A customer did built it with the Clark Y flies good as well but inverted see above.
Peter
Waco Brother #170
Iassumed it had to do with aerobatic preformance, but Iwanted to make sure Iwasn't missing something.
Joe
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RE: WACO YMF
Jaybird, I think the reason young men aren't building is they have more money then time .
Plus look at the quality of the ARF's.
I belong to a club of about 60 members and there may be 2 or 3 guys who build.
Bill
WB126
Plus look at the quality of the ARF's.
I belong to a club of about 60 members and there may be 2 or 3 guys who build.
Bill
WB126
RE: WACO YMF
ORIGINAL: nine o nine
Hello Albert, You've done some BEAUTIFUL work! I see on your landing gear profile you may have done what some kit makers have done... that the rear edge should end up behind the wing leading edge. That makes the whole triangle shape different. If you're not after 100% scale accuracy it'll be fine and much easier from an engineering standpoint.
I love the build. Mitch
Hello Albert, You've done some BEAUTIFUL work! I see on your landing gear profile you may have done what some kit makers have done... that the rear edge should end up behind the wing leading edge. That makes the whole triangle shape different. If you're not after 100% scale accuracy it'll be fine and much easier from an engineering standpoint.
I love the build. Mitch
A few new pics ...Of course I saw that the original chassis are made differently. But, it is quite difficult to run ...So I did just that. Has probably become, when I will make a 40% scale model I will try to make an absolutely exact copy.
Albert
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RE: WACO YMF
FMBB, Thank you sir. I had missed your post on my 1st read after being gone awhile.
Bill
WB126
AMA6416 and waiting for Bill WB#1 to tell us again his AMA#?
Bill
WB126
AMA6416 and waiting for Bill WB#1 to tell us again his AMA#?
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RE: WACO YMF
Sorry, sorry, sorry! It was meant as a joke as it is another subject that gets everyone worked up.
Besides, I didn't actually ask the question, I just noted that it too has a lot of strong opinions.
I worked on adding the javelins to the new flying wires on my GP WACO ARF last evening and should have it finished tonight.
Jaybird
Besides, I didn't actually ask the question, I just noted that it too has a lot of strong opinions.
I worked on adding the javelins to the new flying wires on my GP WACO ARF last evening and should have it finished tonight.
Jaybird