World Models Ultimate 40S
11-28-2005, 01:57 PM
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RE: World Models Ultimate 40S
Greg,
Just a postscript -- I forgot to tell you that yes, my CG was exactly at the recommended point. My aircraft came in a little heavy at almost 5 pounds due to an extra servo for the ailerons which I converted to flaperons (but never got to check out) and for larger landing gear to better take our grass runway. I also had some extra servo supports for two external servos on the fuselage near the tail structure and I think I used larger servos than the prototype. I was able to get the CG forward with just the battery and receiver location and did not have to add ballast.
I was a little concerned about the larger gear producing a higher deck angle which could make takeoff squirrelly -- but, this did not seem to be the case; takeoff was not a problem.
Regards, Dick
Just a postscript -- I forgot to tell you that yes, my CG was exactly at the recommended point. My aircraft came in a little heavy at almost 5 pounds due to an extra servo for the ailerons which I converted to flaperons (but never got to check out) and for larger landing gear to better take our grass runway. I also had some extra servo supports for two external servos on the fuselage near the tail structure and I think I used larger servos than the prototype. I was able to get the CG forward with just the battery and receiver location and did not have to add ballast.
I was a little concerned about the larger gear producing a higher deck angle which could make takeoff squirrelly -- but, this did not seem to be the case; takeoff was not a problem.
Regards, Dick
11-28-2005, 04:01 PM
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RE: World Models Ultimate 40S
Dick:
Excuse me from replying, things are kinda slow in the office after the holiday. I understand your delema, you certainly don't want to experience the same situation with the replacement model.
Perhaps you should contact the retailer of the kit, if they find that there is an error in computing the CG, the replacement kit might be free. Greg is an electrical engineer and that is one heck of a computation that we don't find in ARF kits. I'm afraid, if we deviate too much from Greg's area of expertise he might get a big head ache and not be able to work on the other gas to electric conversions that we are waiting to hear about. It might really help if you list the steps to your computation in order, like an outline format, instead of paragraph form. I, for one, would like to learn the CG calculations, however, reading the paragrah made it seem harder to follow. I work with number all day, however, I really like to see the facts as definitions to the formula, similar to beginning algebra. Here is the formula, then listed below is the measurements and procedure to carry out the formula, in step form.
Spin recovery: Ah yes, easy to know the procedures, but, very hard to do it when not riding in the plane. Lets see, kill the throttle, use ailerons to stop the spin, pull out of the resulting dive while adding power back to straight and level. Be carefull not to pull the plane into another stall when revovering from the dive.
You pinpointed the exact situation that a person has when flying a craft using radio control, it is very difficult to diagnose the problem without being in the plane. With all the noise that takes place at the RC airport, and the distance of the plane from where the operator is standing, most of the time we can't even tell if there is a engine out.
Al Gutkin
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Excuse me from replying, things are kinda slow in the office after the holiday. I understand your delema, you certainly don't want to experience the same situation with the replacement model.
Perhaps you should contact the retailer of the kit, if they find that there is an error in computing the CG, the replacement kit might be free. Greg is an electrical engineer and that is one heck of a computation that we don't find in ARF kits. I'm afraid, if we deviate too much from Greg's area of expertise he might get a big head ache and not be able to work on the other gas to electric conversions that we are waiting to hear about. It might really help if you list the steps to your computation in order, like an outline format, instead of paragraph form. I, for one, would like to learn the CG calculations, however, reading the paragrah made it seem harder to follow. I work with number all day, however, I really like to see the facts as definitions to the formula, similar to beginning algebra. Here is the formula, then listed below is the measurements and procedure to carry out the formula, in step form.
Spin recovery: Ah yes, easy to know the procedures, but, very hard to do it when not riding in the plane. Lets see, kill the throttle, use ailerons to stop the spin, pull out of the resulting dive while adding power back to straight and level. Be carefull not to pull the plane into another stall when revovering from the dive.
You pinpointed the exact situation that a person has when flying a craft using radio control, it is very difficult to diagnose the problem without being in the plane. With all the noise that takes place at the RC airport, and the distance of the plane from where the operator is standing, most of the time we can't even tell if there is a engine out.
Al Gutkin
When I talk, only the people that pay me listen.
11-28-2005, 04:52 PM
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RE: World Models Ultimate 40S
ORIGINAL: algutkin
Spin recovery: Ah yes, easy to know the procedures, but, very hard to do it when not riding in the plane. Lets see, kill the throttle, use ailerons to stop the spin, pull out of the resulting dive while adding power back to straight and level. Be carefull not to pull the plane into another stall when revovering from the dive.
Spin recovery: Ah yes, easy to know the procedures, but, very hard to do it when not riding in the plane. Lets see, kill the throttle, use ailerons to stop the spin, pull out of the resulting dive while adding power back to straight and level. Be carefull not to pull the plane into another stall when revovering from the dive.
11-28-2005, 05:10 PM
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RE: World Models Ultimate 40S
You're right, I forgot. It's been years since spin training, I forgot about the rudder. What I remember most is to stop the spin and recover from the resulting dive without overspeeding or recovering into a stall. That works except in flat spins, then it takes power to recover. I had to do it from with the hood on many times, somehow it was easier without the windshield view. I learned, if you don't like what you see out the windshield, close your eyes..LOL I seem to practice the same thing with RC aircraft, not good.
Sometimes we tend to open mouth, then put foot in. I remember saying that I don't need spin training, modern aircraft are engineered to avoid spins. What a joke, that means that they are harder to recover when, and if, they inadvertantly get into a spin. I understand that most normal designed aircraft will recover hands off. How about RC aircraft?
Thanks for the correction
Al Gutkin
Sometimes we tend to open mouth, then put foot in. I remember saying that I don't need spin training, modern aircraft are engineered to avoid spins. What a joke, that means that they are harder to recover when, and if, they inadvertantly get into a spin. I understand that most normal designed aircraft will recover hands off. How about RC aircraft?
Thanks for the correction
Al Gutkin
11-28-2005, 06:01 PM
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RE: World Models Ultimate 40S
Dick,
Thanks for the CG calculation. I'll have it looked at and see if the CG is incorrect from the manufacturer.
Al,
Don't worry, I can multitask pretty good.
Thanks for the CG calculation. I'll have it looked at and see if the CG is incorrect from the manufacturer.
Al,
Don't worry, I can multitask pretty good.
11-28-2005, 06:11 PM
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RE: World Models Ultimate 40S
I'm using the new Phoenix [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXLBY3&P=7]HV 45 ESC[/link] from Castle Creations to control my Kontronik 600 brushless motor. The ESC is rated at over 2000 watts so it will easily handle my 1000 watt application with minimal cooling.
A 6v [link=http://www.hobby-lobby.com/ubec.htm]UBEC[/link] from Hobby Lobby provides the receiver and servo power from the main battery so you never need to charge a second Rx. pack.
I like using the Tower Hobbies [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJC15&P=ML]System 3000 On/Off Switch Harness[/link] to keep the power system disabled until I'm ready to fly.
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A 6v [link=http://www.hobby-lobby.com/ubec.htm]UBEC[/link] from Hobby Lobby provides the receiver and servo power from the main battery so you never need to charge a second Rx. pack.
I like using the Tower Hobbies [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJC15&P=ML]System 3000 On/Off Switch Harness[/link] to keep the power system disabled until I'm ready to fly.
The Jeti [link=http://www.hobby-lobby.com/connectors.htm]3.5mm Gold Connectors[/link] are also from Hobby Lobby.
11-28-2005, 07:05 PM
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RE: World Models Ultimate 40S
Greg ... this is my first foray into "higher amp" applications. (I typically use setups not drawing more than 25 amps) I have always used 35A powerpole (Sermos) connectors with my current setups.
Do I now need to use higher amp connectors since my setup with this Ultimate is probably gonna draw about 40A to 50A? If so ... what do you recommend?
Colin.
Do I now need to use higher amp connectors since my setup with this Ultimate is probably gonna draw about 40A to 50A? If so ... what do you recommend?
Colin.
11-28-2005, 07:12 PM
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RE: World Models Ultimate 40S
I also appreciate how you showed the connections in the second pic with the ESC, UBEC etc . (I've never used a UBEC or separate BEC of any kind before ... again because of my inexperience with higher voltage/amp applications)
When you get to that stage, could you also show how the UBEC will connect to the switch?
Thanks!
Colin.
When you get to that stage, could you also show how the UBEC will connect to the switch?
Thanks!
Colin.
11-28-2005, 07:23 PM
#34
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RE: World Models Ultimate 40S
Colin,
Sure, no problem. Sometimes I limit the detail because I've done it many times before and forget that each review could be someone's first attempt at a model this size.
The UBEC's 6v output is simply plugged into the S3K On/Off switch harness, which in turn, is plugged into any free receiver channel. The receiver, servos, and Opto ESC remain off until the switch is turned on. In this manner, you can plug in the battery and attach the wing without the plane being on. For safety, always keep clear of the prop when the battery is plugged in, even if the switch is set to Off.
The PowerPole connectors will work fine. They are conservatively rated at 35 amps continuous.
Sure, no problem. Sometimes I limit the detail because I've done it many times before and forget that each review could be someone's first attempt at a model this size.
The UBEC's 6v output is simply plugged into the S3K On/Off switch harness, which in turn, is plugged into any free receiver channel. The receiver, servos, and Opto ESC remain off until the switch is turned on. In this manner, you can plug in the battery and attach the wing without the plane being on. For safety, always keep clear of the prop when the battery is plugged in, even if the switch is set to Off.
The PowerPole connectors will work fine. They are conservatively rated at 35 amps continuous.
11-28-2005, 07:40 PM
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RE: World Models Ultimate 40S
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11-29-2005, 12:15 AM
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RE: World Models Ultimate 40S
ORIGINAL: Greg Covey
The PowerPole connectors will work fine. They are conservatively rated at 35 amps continuous.
The PowerPole connectors will work fine. They are conservatively rated at 35 amps continuous.
Colin.
11-29-2005, 02:12 AM
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RE: World Models Ultimate 40S
Colin:
To check for amp capability. I'm not an engineer so I do it the old fashioned way. Run the device at full, feel the wires, feel the connectors, if they are not hot, then good to go. Us non-engineer types use the visual estimate method of checking things. We don't sit there and analyze the weight carring capacity of that typewriter table, it would stop the production of the office. We don't dig around for specs., or call the manufacturer, we just put the typwriter on it, check for stability, if OK, then wala, we have a good setup. You can't build a bridge that way, but it sure works for typewriter tables. LOL
Al
To check for amp capability. I'm not an engineer so I do it the old fashioned way. Run the device at full, feel the wires, feel the connectors, if they are not hot, then good to go. Us non-engineer types use the visual estimate method of checking things. We don't sit there and analyze the weight carring capacity of that typewriter table, it would stop the production of the office. We don't dig around for specs., or call the manufacturer, we just put the typwriter on it, check for stability, if OK, then wala, we have a good setup. You can't build a bridge that way, but it sure works for typewriter tables. LOL
Al
11-29-2005, 09:48 AM
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RE: World Models Ultimate 40S
Dick,
It appears that your calculations are correct, assuming the dimensions are correct, and, you want it balanced at 25% average mean cord. Many skilled pilots will fly a ship balanced at 33% to 35% AMC, but, it can be a real surprise at times, especially if the plane has a heavy wing loading. This CG is not recommended for test flights.
I will bring this to the attention of the U.S. distributor for World Models and see what he has to say.
Colin,
My feeling is that this power level (about 1000 watts) doesn't even come close to the limitations of the PowerPole connectors.
It appears that your calculations are correct, assuming the dimensions are correct, and, you want it balanced at 25% average mean cord. Many skilled pilots will fly a ship balanced at 33% to 35% AMC, but, it can be a real surprise at times, especially if the plane has a heavy wing loading. This CG is not recommended for test flights.
I will bring this to the attention of the U.S. distributor for World Models and see what he has to say.
Colin,
My feeling is that this power level (about 1000 watts) doesn't even come close to the limitations of the PowerPole connectors.
11-29-2005, 12:50 PM
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RE: World Models Ultimate 40S
Greg,
I appreciate your willingness to discuss this with the distributor and look forward to his reply. As I said, I definitely will fly this AC again and I would like to have confidence in a good CG. I too have had a couple of models that I balanced at 30 to 32% but these were proven stable models with much flying time. At 35%, you are at the theoretical neutral stability point and I am sure that there are AC that are safe here -- but it is prudent to approach this condition slowly and carefully.
Please let me know what you find out.
Dick
I appreciate your willingness to discuss this with the distributor and look forward to his reply. As I said, I definitely will fly this AC again and I would like to have confidence in a good CG. I too have had a couple of models that I balanced at 30 to 32% but these were proven stable models with much flying time. At 35%, you are at the theoretical neutral stability point and I am sure that there are AC that are safe here -- but it is prudent to approach this condition slowly and carefully.
Please let me know what you find out.
Dick
11-29-2005, 01:38 PM
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RE: World Models Ultimate 40S
ORIGINAL: ropowell
The suggested CG point would be 25% of the MAC or 1.97 inches back from the leading edge of the wing AT THE LOCATION OF THE MAC which is 10 1/2 inches out from the center of the fuselage. I called this 2 inches for convenience and now it must be projected over to the CL of the fuselage. So to get the CG location at the CL, we must add half of the sweep or 1.75/2 = 7/8 inch added to the 2 inch which gives 2 7/8 inches for the CG measurement at the CL of the fuselage.
The suggested CG point would be 25% of the MAC or 1.97 inches back from the leading edge of the wing AT THE LOCATION OF THE MAC which is 10 1/2 inches out from the center of the fuselage. I called this 2 inches for convenience and now it must be projected over to the CL of the fuselage. So to get the CG location at the CL, we must add half of the sweep or 1.75/2 = 7/8 inch added to the 2 inch which gives 2 7/8 inches for the CG measurement at the CL of the fuselage.
Isn't easier to balance at THAT position (location of the MAC) as opposed to doing it from the CL? Since I saw the manufacturer's diagram that Greg posted of their CG suggestion (at the CL location) I've been scratching my newbie head as to how one would PRACTICALLY go about measuring the CG from that location. (I've always measured the CG of my models from the recommended CG position on either side of the wing relatively close to the fuse.)
BTW, is all of this happening from the TOP wing or the bottom? I'm relatively new to Bipes (my current M-12 Pitts is my first) but I measured mine from the MAC location on the top wing. Are all Bipes the same or is this CL measuring location thing more common to Bipes?
Thanks,
Colin.
11-29-2005, 04:00 PM
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RE: World Models Ultimate 40S
Hi Colin,
Your question is a good one and hopefully I can give you a satisfactory answer. The CG should always be determined at the mean aerodynamic chord (MAC) and yes, it makes sense to measure it at this same location. In the case in question, the manufacturor gave the CG location at the centerline of the fuselage and my purpose was to compare my results with his. When you are given the CG at any point, you may balance the AC at any point you wish just as long as it's on a line through the CG and perpendicular to the centerline of the fuselage. Usually, I prefer to balance at the wingtip since I use the old finger pivot for balancing rather than the newer and more accurate instuments available for this. So, in the present case, I would take the 2 inch measurement back from the leading edge of the TOP wing at the MAC and project it out to the wingtip. To do this, subtract 1/2 of the wing sweep or 7/8 inch from the 2 inches to obtain 1 1/8 inch. So, I mark a point 1 1/8 inch back from the leading edge of the top wing on each wingtip and then balance the AC at this point. Yes, I need a friend at the other wingtip.
The reason we're using the top wing is that the effective wing of a biplane is the projected wing that you would see if you could look straight down on the two wings. In the case of this AC, you would see the leading edge of the top wing and the trailing edge of the bottom wing. We pretend that we have a single wing with this projected outline and because of convention we measure the CG from the leading edge although mathematically, we could just a well take our measurements from the trailing edge.
I hope that I have cleared the water rather than muddy it up! At any rate, never be afraid to ask a question and if you have others, just let me know. One last point, when you're checking balance, be sure that the AC balances exactly level at the desired point. I've often heard friends say " I balanced it at the correct point but a little nose up." That's like saying I had it perfect but it was off -- I don't really know how much.
I just went back and reread your post and there is another item that I may need to mention. The MAC doesn't always occur at the midpoint of the wing panel. This is only true for a rectangular wing (ie constant chord) with or without sweep. For a wing having reduced chord at the tip, with or without sweep, the MAC may be determined by graphical techniques available in many AC design books or if you have an engineering background, the MAC occurs at the centroid of the area of the half wing. If this doesn't make sense, don't worry -- most of the time the published CG points are correct and just remember, you can balance at any point on the line perpendicular to the fuselage.
Dick
Your question is a good one and hopefully I can give you a satisfactory answer. The CG should always be determined at the mean aerodynamic chord (MAC) and yes, it makes sense to measure it at this same location. In the case in question, the manufacturor gave the CG location at the centerline of the fuselage and my purpose was to compare my results with his. When you are given the CG at any point, you may balance the AC at any point you wish just as long as it's on a line through the CG and perpendicular to the centerline of the fuselage. Usually, I prefer to balance at the wingtip since I use the old finger pivot for balancing rather than the newer and more accurate instuments available for this. So, in the present case, I would take the 2 inch measurement back from the leading edge of the TOP wing at the MAC and project it out to the wingtip. To do this, subtract 1/2 of the wing sweep or 7/8 inch from the 2 inches to obtain 1 1/8 inch. So, I mark a point 1 1/8 inch back from the leading edge of the top wing on each wingtip and then balance the AC at this point. Yes, I need a friend at the other wingtip.
The reason we're using the top wing is that the effective wing of a biplane is the projected wing that you would see if you could look straight down on the two wings. In the case of this AC, you would see the leading edge of the top wing and the trailing edge of the bottom wing. We pretend that we have a single wing with this projected outline and because of convention we measure the CG from the leading edge although mathematically, we could just a well take our measurements from the trailing edge.
I hope that I have cleared the water rather than muddy it up! At any rate, never be afraid to ask a question and if you have others, just let me know. One last point, when you're checking balance, be sure that the AC balances exactly level at the desired point. I've often heard friends say " I balanced it at the correct point but a little nose up." That's like saying I had it perfect but it was off -- I don't really know how much.
I just went back and reread your post and there is another item that I may need to mention. The MAC doesn't always occur at the midpoint of the wing panel. This is only true for a rectangular wing (ie constant chord) with or without sweep. For a wing having reduced chord at the tip, with or without sweep, the MAC may be determined by graphical techniques available in many AC design books or if you have an engineering background, the MAC occurs at the centroid of the area of the half wing. If this doesn't make sense, don't worry -- most of the time the published CG points are correct and just remember, you can balance at any point on the line perpendicular to the fuselage.
Dick
11-29-2005, 04:29 PM
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RE: World Models Ultimate 40S
Hi Al,
I enjoyed your post and I must say, I too prefer simple algebraic exercises. Therefore, I hereby apologize for the verbose presentation. Unfortunately, I don't believe I can really do much to improve this without having the use of graphic diagrams. Actually, everything I originally did for this study was done in a graphics program, AutoCad. If I could send you this drawing, I believe you would readily understand what I struggled so hard to say.
At any rate, thanks for the interest. And I don't think it will surprise you that I am a retired engineering professor of 41 years experience. Now you know why!
Dick
I enjoyed your post and I must say, I too prefer simple algebraic exercises. Therefore, I hereby apologize for the verbose presentation. Unfortunately, I don't believe I can really do much to improve this without having the use of graphic diagrams. Actually, everything I originally did for this study was done in a graphics program, AutoCad. If I could send you this drawing, I believe you would readily understand what I struggled so hard to say.
At any rate, thanks for the interest. And I don't think it will surprise you that I am a retired engineering professor of 41 years experience. Now you know why!
Dick
11-29-2005, 05:23 PM
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RE: World Models Ultimate 40S
ORIGINAL: ropowell
Hi Colin,
Your question is a good one and hopefully I can give you a satisfactory answer. The CG should always be determined at the mean aerodynamic chord (MAC) and yes, it makes sense to measure it at this same location. In the case in question, the manufacturor gave the CG location at the centerline of the fuselage and my purpose was to compare my results with his. When you are given the CG at any point, you may balance the AC at any point you wish just as long as it's on a line through the CG and perpendicular to the centerline of the fuselage. Usually, I prefer to balance at the wingtip since I use the old finger pivot for balancing rather than the newer and more accurate instuments available for this. So, in the present case, I would take the 2 inch measurement back from the leading edge of the TOP wing at the MAC and project it out to the wingtip. To do this, subtract 1/2 of the wing sweep or 7/8 inch from the 2 inches to obtain 1 1/8 inch. So, I mark a point 1 1/8 inch back from the leading edge of the top wing on each wingtip and then balance the AC at this point. Yes, I need a friend at the other wingtip.
The reason we're using the top wing is that the effective wing of a biplane is the projected wing that you would see if you could look straight down on the two wings. In the case of this AC, you would see the leading edge of the top wing and the trailing edge of the bottom wing. We pretend that we have a single wing with this projected outline and because of convention we measure the CG from the leading edge although mathematically, we could just a well take our measurements from the trailing edge.
I hope that I have cleared the water rather than muddy it up! At any rate, never be afraid to ask a question and if you have others, just let me know. One last point, when you're checking balance, be sure that the AC balances exactly level at the desired point. I've often heard friends say " I balanced it at the correct point but a little nose up." That's like saying I had it perfect but it was off -- I don't really know how much.
I just went back and reread your post and there is another item that I may need to mention. The MAC doesn't always occur at the midpoint of the wing panel. This is only true for a rectangular wing (ie constant chord) with or without sweep. For a wing having reduced chord at the tip, with or without sweep, the MAC may be determined by graphical techniques available in many AC design books or if you have an engineering background, the MAC occurs at the centroid of the area of the half wing. If this doesn't make sense, don't worry -- most of the time the published CG points are correct and just remember, you can balance at any point on the line perpendicular to the fuselage.
Dick
Hi Colin,
Your question is a good one and hopefully I can give you a satisfactory answer. The CG should always be determined at the mean aerodynamic chord (MAC) and yes, it makes sense to measure it at this same location. In the case in question, the manufacturor gave the CG location at the centerline of the fuselage and my purpose was to compare my results with his. When you are given the CG at any point, you may balance the AC at any point you wish just as long as it's on a line through the CG and perpendicular to the centerline of the fuselage. Usually, I prefer to balance at the wingtip since I use the old finger pivot for balancing rather than the newer and more accurate instuments available for this. So, in the present case, I would take the 2 inch measurement back from the leading edge of the TOP wing at the MAC and project it out to the wingtip. To do this, subtract 1/2 of the wing sweep or 7/8 inch from the 2 inches to obtain 1 1/8 inch. So, I mark a point 1 1/8 inch back from the leading edge of the top wing on each wingtip and then balance the AC at this point. Yes, I need a friend at the other wingtip.
The reason we're using the top wing is that the effective wing of a biplane is the projected wing that you would see if you could look straight down on the two wings. In the case of this AC, you would see the leading edge of the top wing and the trailing edge of the bottom wing. We pretend that we have a single wing with this projected outline and because of convention we measure the CG from the leading edge although mathematically, we could just a well take our measurements from the trailing edge.
I hope that I have cleared the water rather than muddy it up! At any rate, never be afraid to ask a question and if you have others, just let me know. One last point, when you're checking balance, be sure that the AC balances exactly level at the desired point. I've often heard friends say " I balanced it at the correct point but a little nose up." That's like saying I had it perfect but it was off -- I don't really know how much.
I just went back and reread your post and there is another item that I may need to mention. The MAC doesn't always occur at the midpoint of the wing panel. This is only true for a rectangular wing (ie constant chord) with or without sweep. For a wing having reduced chord at the tip, with or without sweep, the MAC may be determined by graphical techniques available in many AC design books or if you have an engineering background, the MAC occurs at the centroid of the area of the half wing. If this doesn't make sense, don't worry -- most of the time the published CG points are correct and just remember, you can balance at any point on the line perpendicular to the fuselage.
Dick
So ... in laymans terms here's my understanding.
1. In THIS particular AC I can balance it from its MAC (2 inches from the LE) .... OR ... I can balance it from the wing tips, (1 1/8 inches from the LE) ... OR ... I can balance it from its CL. (2 7/8 inches from the LE).
2. Always balance a Bipe from the top wing.
Did I get it?
Colin.
11-29-2005, 10:08 PM
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RE: World Models Ultimate 40S
Yep Dick, it explains everything. Greg is an engineer also, he talks your language along with the other participants in this thread. The only problem that I see, is that, with so much talking, the project won't ever get completed. LOL
Me, I am a working public accountant. In my world, 1 plus 1 equals 2, except, if I want to change it, Somtimes it equals almost 2 or perhaps more than two. We just make adjustments to balance. I tell my cleints that accounting is math, everything must balance. Then, after saying that, I have to turn my head so they won't see my nose getting bigger.
OK, let me help with the way I think it should be done.
1. I measured from here to here and got=this ( which is called ? in formal terms)
2. I then measured from there to there and got=that (which is called ? in formal terms)
3. I then took the measurements from 1 and 2 and did this to arrive at=whatever (which is called ? is formal terms)
4. I then devided the answer in 3 by 2 to arrive at the balance point close to the fuse which equals ?
5. If you want to balance at the wing tips you must skip 4 and devided by pie to get the finger point measurements back from tips. Be carefull, don't let the plane slip off your fingers aft, or you might dent the tail serface.
See that was easy, you just have to fill in the easy to understand steps. Pretend you are an electrical installer looking at a simple schematic for wiring an aircraft radio. The drawing shows the black wire going to ground, the red wire goes to plus. The other wires indicated in the schematic drawing are just as easy to follow. All you have to do is find the right color wires and know how to solder or crimp. I wired many aircraft radios into various airplanes by following the schematics. They all worked perfectly when turned on. Greg and you other engineers just like making things look complicated. LOL
C'mon make it simple for us dummies.
Al Gutkin
Me, I am a working public accountant. In my world, 1 plus 1 equals 2, except, if I want to change it, Somtimes it equals almost 2 or perhaps more than two. We just make adjustments to balance. I tell my cleints that accounting is math, everything must balance. Then, after saying that, I have to turn my head so they won't see my nose getting bigger.
OK, let me help with the way I think it should be done.
1. I measured from here to here and got=this ( which is called ? in formal terms)
2. I then measured from there to there and got=that (which is called ? in formal terms)
3. I then took the measurements from 1 and 2 and did this to arrive at=whatever (which is called ? is formal terms)
4. I then devided the answer in 3 by 2 to arrive at the balance point close to the fuse which equals ?
5. If you want to balance at the wing tips you must skip 4 and devided by pie to get the finger point measurements back from tips. Be carefull, don't let the plane slip off your fingers aft, or you might dent the tail serface.
See that was easy, you just have to fill in the easy to understand steps. Pretend you are an electrical installer looking at a simple schematic for wiring an aircraft radio. The drawing shows the black wire going to ground, the red wire goes to plus. The other wires indicated in the schematic drawing are just as easy to follow. All you have to do is find the right color wires and know how to solder or crimp. I wired many aircraft radios into various airplanes by following the schematics. They all worked perfectly when turned on. Greg and you other engineers just like making things look complicated. LOL
C'mon make it simple for us dummies.
Al Gutkin
11-30-2005, 07:54 AM
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RE: World Models Ultimate 40S
Al,
You didn't think that I would leave you without a clear statement before I was done, did you?
Ok, since you forced my hand, here it goes. According to Dick's findings, we now feel that the correct starting point for the CG for test flying is 2-7/8" (not 3-3/4) back from the LE of the top wing. The 3-3/4" CG in the manual appears to be for extreme performance once you are familiar with the bipe and have advanced flying skills.
By the way, we need your accounting math in many aspects of life.
You didn't think that I would leave you without a clear statement before I was done, did you?
Ok, since you forced my hand, here it goes. According to Dick's findings, we now feel that the correct starting point for the CG for test flying is 2-7/8" (not 3-3/4) back from the LE of the top wing. The 3-3/4" CG in the manual appears to be for extreme performance once you are familiar with the bipe and have advanced flying skills.
By the way, we need your accounting math in many aspects of life.
11-30-2005, 08:01 AM
#46
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RE: World Models Ultimate 40S
It is usually best to test the system before mounting the components inside the fuselage. This is also a good time to determine proper motor direction as there is little reason to the wire color coding on ESCs and motors and it varies depending upon a geared or direct drive solution. Fortunately, you only need to swap any two of the three motor wires to reverse the direction of rotation.
You can mount the components using either Velcro or servo tape. I typically mount my On/Off switch so that ON faces the front toward the motor. The left area where the UBEC resides will be covered by the servo tray. The flight pack will side by the receiver up front behind the firewall.
My M5 v2 receiver using a white antenna wire so I routed it through the bottom of the fuselage and taped it back to the tail. Sometimes, if the fuselage is sufficiently long, you can run the wire through a plastic tube and keep it inside the fuselage.
You can mount the components using either Velcro or servo tape. I typically mount my On/Off switch so that ON faces the front toward the motor. The left area where the UBEC resides will be covered by the servo tray. The flight pack will side by the receiver up front behind the firewall.
My M5 v2 receiver using a white antenna wire so I routed it through the bottom of the fuselage and taped it back to the tail. Sometimes, if the fuselage is sufficiently long, you can run the wire through a plastic tube and keep it inside the fuselage.
11-30-2005, 08:12 AM
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RE: World Models Ultimate 40S
Al,
I'm glad you found a way that works for you -- I would call it "Cookbook" style. And like wiring diagrams, it's a great way to tell someone how to accomplish simple (sometimes) repetitive tasks. As an engineer, I would rather tell you what is being done and then if you understand, you should be able to execute similar calculations even if there are changes, say for instance, if there were no sweep or perhaps forward sweep or what if you were working on an aircraft like the Beech Staggerwing which of course had reverse stagger. At any rate, I'm not trying to be argumentative -- just sharing ideas -- and I guess that's what it all about in our hobby.
Colin,
Sounds like you have it! With one possible addition. There is no requirement to use the top wing for the actual balancing. Just as you can project the balance point to the fuselage centerline or to the wingtip, you may also project it down to the lower wing and do the balancing here if you prefer. Remember that for a biplane, we change the two wings into a single "effective" wing which is the plan view that we see looking straight down on the wings. We would then determine the MAC for this wing and make measurements back from its leading edge which for the Beech mentioned above would be the lower wing.
I'm glad you found a way that works for you -- I would call it "Cookbook" style. And like wiring diagrams, it's a great way to tell someone how to accomplish simple (sometimes) repetitive tasks. As an engineer, I would rather tell you what is being done and then if you understand, you should be able to execute similar calculations even if there are changes, say for instance, if there were no sweep or perhaps forward sweep or what if you were working on an aircraft like the Beech Staggerwing which of course had reverse stagger. At any rate, I'm not trying to be argumentative -- just sharing ideas -- and I guess that's what it all about in our hobby.
Colin,
Sounds like you have it! With one possible addition. There is no requirement to use the top wing for the actual balancing. Just as you can project the balance point to the fuselage centerline or to the wingtip, you may also project it down to the lower wing and do the balancing here if you prefer. Remember that for a biplane, we change the two wings into a single "effective" wing which is the plan view that we see looking straight down on the wings. We would then determine the MAC for this wing and make measurements back from its leading edge which for the Beech mentioned above would be the lower wing.
11-30-2005, 08:58 AM
#48
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RE: World Models Ultimate 40S
Here is a layout diagram in both block and picture form. It shows the component inter-connections except for the On/Off switch assembly that is inserted between the Rx. pack (or UBEC) and the spare receiver channel.
11-30-2005, 10:07 AM
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RE: World Models Ultimate 40S
Thanks Greg for the balance answer and Oh yes, test everything first. I forgot about reversing the wires and had a plane that tried to taxi backward.
Dick: I really like to learn new things. I'm sure I read the formula for calculating the balance point in aircraft, however, I'm also sure that I got a head ache before finishing the paragraph. The tax code is written in engineering terms, I make it simple, then apply it to suit my cleint's needs. LOL ...Dick, how would teach a 12 year old to compute the balance point? Don't forget, the older we get, the younger we get. LOL
Is the balance point the mean cord of the wing? I heard that term somewhere. Why are planes with s short fuse harder to balance?
Al
Dick: I really like to learn new things. I'm sure I read the formula for calculating the balance point in aircraft, however, I'm also sure that I got a head ache before finishing the paragraph. The tax code is written in engineering terms, I make it simple, then apply it to suit my cleint's needs. LOL ...Dick, how would teach a 12 year old to compute the balance point? Don't forget, the older we get, the younger we get. LOL
Is the balance point the mean cord of the wing? I heard that term somewhere. Why are planes with s short fuse harder to balance?
Al
11-30-2005, 04:15 PM
#50
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Thread Starter
RE: World Models Ultimate 40S
Fai Chan from AirBorne Models reported the following:
I checked with the factory on their flying test record, they did have the prototype tested at 3 3/4 in. CG. Not sure if the test pilot had very skillful hands or they have added some off record nose weight. I went through the calculations and I agreed that the CG is too far back. I think 3 in. from leading edge of top wing is about right. Please try this and let me know if it works.
Thanks again.
Thanks again.