40% 260 on a Diet
12-30-2006, 10:19 AM
#55
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RE: 40% 260 on a Diet
260man,
I have no doubt that you will have an extremely light 260 but don't you think that by removing the side sheeting and all of the diagonal braces that you will have an airplane that will twist like a pretzel every time you touch the aileron stick. One of the things that make a carden fly so well is that extremely rigid fuse that doesn't twist.
Albert
I have no doubt that you will have an extremely light 260 but don't you think that by removing the side sheeting and all of the diagonal braces that you will have an airplane that will twist like a pretzel every time you touch the aileron stick. One of the things that make a carden fly so well is that extremely rigid fuse that doesn't twist.
Albert
12-30-2006, 08:17 PM
#56
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RE: 40% 260 on a Diet
ORIGINAL: as722
260man,
I have no doubt that you will have an extremely light 260 but don't you think that by removing the side sheeting and all of the diagonal braces that you will have an airplane that will twist like a pretzel every time you touch the aileron stick. One of the things that make a carden fly so well is that extremely rigid fuse that doesn't twist.
Albert
260man,
I have no doubt that you will have an extremely light 260 but don't you think that by removing the side sheeting and all of the diagonal braces that you will have an airplane that will twist like a pretzel every time you touch the aileron stick. One of the things that make a carden fly so well is that extremely rigid fuse that doesn't twist.
Albert
What makes you think it will twist. I have checked it over and over as I am building and there is NO twist... NONE...........
The span of the verticals are reduced from the plan (I added more vertical balsa sticks). I did install the cross braces per the plan along the top of the aircraft. In the canopy area, I will add some diagonals because there is no top support, such as the tail and bottom. The turtle deck and the bottom decking ads strength reducing twist. One other thing that most people will not think about is that the covering has a 25,000 PSI tensile strength. Look at this web site http://gaboats.com/tutorials/monokote.html
The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before failure. The definition of failure can vary according to material type and design methodology. This is an important concept in engineering, especially in the fields of material science, mechanical engineering and structural engineering.
There are three typical definitions of tensile strength:
• Yield strength - The stress a material can withstand without permanent deformation. This is not a sharply defined point. Yield strength is the stress which will cause a permanent deformation of 0.2% of the original dimension.
• Ultimate strength - The maximum stress a material can withstand.
• Breaking strength - The stress coordinate on the stress-strain curve at the point of rupture.
I hope this helps………
12-30-2006, 08:46 PM
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RE: 40% 260 on a Diet
Why double the verticals and take out the cross bracing that makes no sense from a structural standpoint. If you really wanted to reduce weight you could have added distance between the verticals and kept the diagonals - there's a reason we use triangles to strenghten stuff lol. Added more verticals doesn't help at all. In the vertical plane a few verticals would have been enough. It's the other planes that needed the help. You added strenth you didn't need and took away what you did need.
12-30-2006, 09:02 PM
#59
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RE: 40% 260 on a Diet
ORIGINAL: Bob101
Why double the verticals and take out the cross bracing that makes no sense from a structural standpoint. If you really wanted to reduce weight you could have added distance between the verticals and kept the diagonals - there's a reason we use triangles to strenghten stuff lol. Added more verticals doesn't help at all. In the vertical plane a few verticals would have been enough. It's the other planes that needed the help. You added strenth you didn't need and took away what you did need.
Why double the verticals and take out the cross bracing that makes no sense from a structural standpoint. If you really wanted to reduce weight you could have added distance between the verticals and kept the diagonals - there's a reason we use triangles to strenghten stuff lol. Added more verticals doesn't help at all. In the vertical plane a few verticals would have been enough. It's the other planes that needed the help. You added strenth you didn't need and took away what you did need.
LOL as you say Bob, there is a reason I chose to build MY aircraft the way I want to.
But thanks for adding your opinion. [sm=tongue_smile.gif]
12-30-2006, 09:19 PM
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RE: 40% 260 on a Diet
I dont know much about Tensile strength but are are you saying that the covering will help hold this plane together?
I've seen covering (Monokote, Ultracote) split because of loads on a twisting airframe.
I've seen covering (Monokote, Ultracote) split because of loads on a twisting airframe.
12-30-2006, 10:18 PM
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RE: 40% 260 on a Diet
I love this thread!!!
I have not seen this much B!tC&ing in one place in a long time!!!
Keep the good work guys!!!
And keep up the good building 260 man! Good luck on your 28lbs, I can't wait to see it fly!
I have not seen this much B!tC&ing in one place in a long time!!!
Keep the good work guys!!!
And keep up the good building 260 man! Good luck on your 28lbs, I can't wait to see it fly!
12-31-2006, 01:13 AM
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RE: 40% 260 on a Diet
I fear for the poeple who show up to watch this banana of a plane fly. Like I said I know someone who built a 35% and didn't get near as radical as you and the sheeting rippled to the point they quit flying it after a few flights...I could literally see you doing a wall/snap or whatever and the tail just ripping off the plane. Oh yeah I don't know much about structures - I'm just an structural engineer by trade.
12-31-2006, 08:12 AM
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RE: 40% 260 on a Diet
260man,
A 25,000 psi tensile strenght on monokote only applies when it is pulled on, it will not prevent your fuse from twisting. It sounds like you have it all figured out and I'm sure you'll get thousands of flights on it without twisting. Good luck with your project.
Albert
A 25,000 psi tensile strenght on monokote only applies when it is pulled on, it will not prevent your fuse from twisting. It sounds like you have it all figured out and I'm sure you'll get thousands of flights on it without twisting. Good luck with your project.
Albert
ORIGINAL: 260 Man
Albert,
What makes you think it will twist. I have checked it over and over as I am building and there is NO twist... NONE...........
The span of the verticals are reduced from the plan (I added more vertical balsa sticks). I did install the cross braces per the plan along the top of the aircraft. In the canopy area, I will add some diagonals because there is no top support, such as the tail and bottom. The turtle deck and the bottom decking ads strength reducing twist. One other thing that most people will not think about is that the covering has a 25,000 PSI tensile strength. Look at this web site http://gaboats.com/tutorials/monokote.html
The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before failure. The definition of failure can vary according to material type and design methodology. This is an important concept in engineering, especially in the fields of material science, mechanical engineering and structural engineering.
There are three typical definitions of tensile strength:
• Yield strength - The stress a material can withstand without permanent deformation. This is not a sharply defined point. Yield strength is the stress which will cause a permanent deformation of 0.2% of the original dimension.
• Ultimate strength - The maximum stress a material can withstand.
• Breaking strength - The stress coordinate on the stress-strain curve at the point of rupture.
I hope this helps………
ORIGINAL: as722
260man,
I have no doubt that you will have an extremely light 260 but don't you think that by removing the side sheeting and all of the diagonal braces that you will have an airplane that will twist like a pretzel every time you touch the aileron stick. One of the things that make a carden fly so well is that extremely rigid fuse that doesn't twist.
Albert
260man,
I have no doubt that you will have an extremely light 260 but don't you think that by removing the side sheeting and all of the diagonal braces that you will have an airplane that will twist like a pretzel every time you touch the aileron stick. One of the things that make a carden fly so well is that extremely rigid fuse that doesn't twist.
Albert
What makes you think it will twist. I have checked it over and over as I am building and there is NO twist... NONE...........
The span of the verticals are reduced from the plan (I added more vertical balsa sticks). I did install the cross braces per the plan along the top of the aircraft. In the canopy area, I will add some diagonals because there is no top support, such as the tail and bottom. The turtle deck and the bottom decking ads strength reducing twist. One other thing that most people will not think about is that the covering has a 25,000 PSI tensile strength. Look at this web site http://gaboats.com/tutorials/monokote.html
The tensile strength of a material is the maximum amount of tensile stress that it can be subjected to before failure. The definition of failure can vary according to material type and design methodology. This is an important concept in engineering, especially in the fields of material science, mechanical engineering and structural engineering.
There are three typical definitions of tensile strength:
• Yield strength - The stress a material can withstand without permanent deformation. This is not a sharply defined point. Yield strength is the stress which will cause a permanent deformation of 0.2% of the original dimension.
• Ultimate strength - The maximum stress a material can withstand.
• Breaking strength - The stress coordinate on the stress-strain curve at the point of rupture.
I hope this helps………
12-31-2006, 09:31 AM
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RE: 40% 260 on a Diet
ORIGINAL: wgeffon
I dont know much about Tensile strength but are are you saying that the covering will help hold this plane together?
I've seen covering (Monokote, Ultracote) split because of loads on a twisting airframe.
I dont know much about Tensile strength but are are you saying that the covering will help hold this plane together?
I've seen covering (Monokote, Ultracote) split because of loads on a twisting airframe.
12-31-2006, 10:58 AM
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RE: 40% 260 on a Diet
ORIGINAL: Bob101
OMG lol now tell me what the compression strength of monokote is compared to it's tensile strength.
OMG lol now tell me what the compression strength of monokote is compared to it's tensile strength.
Respectfully,
ME 260 Man
12-31-2006, 11:25 AM
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RE: 40% 260 on a Diet
Here's some data to ponder. Putting down monokote on top of a piece of 1/16 inch balsa sheeting (light to medium density) increases the strength by 28-73%. Balsa has a tensile strength of 1.1-2.9 ksi, and monokote is 25 ksi.
And now back to the build.....
And now back to the build.....
12-31-2006, 11:58 AM
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RE: 40% 260 on a Diet
ORIGINAL: Diablo-RCU
Yes, the covering really adds quite a bit of strength and stiffness to any model. It is the stressed-skin concept of engineering. Stresses are highest in bending at the surface of a beam (or wing for example). The covering is weak in compression, but if one side is in compression the other side is under tension. Competition fun fly airplanes have used this concept for many years. Ultrakote is much better than monokote (for strength and stiffness of the plane) because it doesn't tear (not as brittle) as easily. However, there is no easy way to predict if the total airframe is strong and stiff enough for the flight loads. Proof comes when it flys.
ORIGINAL: wgeffon
I dont know much about Tensile strength but are are you saying that the covering will help hold this plane together?
I've seen covering (Monokote, Ultracote) split because of loads on a twisting airframe.
I dont know much about Tensile strength but are are you saying that the covering will help hold this plane together?
I've seen covering (Monokote, Ultracote) split because of loads on a twisting airframe.
12-31-2006, 12:42 PM
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RE: 40% 260 on a Diet
ORIGINAL: wgeffon
I say go for it.
This is a Carden 300 that is being built for me right now. Mods are being done to it but nothing more than the typical modded Carden now a days.
Here are some shots of the fuse as it sits right now. What do people think it weighs as it looks in these pics?(Its a little further along than the one this thread is about. It has the tank tray, cannister mount, Tunnel top and the motor mount installed.)
Care to guess?
I say go for it.
This is a Carden 300 that is being built for me right now. Mods are being done to it but nothing more than the typical modded Carden now a days.
Here are some shots of the fuse as it sits right now. What do people think it weighs as it looks in these pics?(Its a little further along than the one this thread is about. It has the tank tray, cannister mount, Tunnel top and the motor mount installed.)
Care to guess?
I was going to guess it weighs about $1600 as shown?
12-31-2006, 01:39 PM
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RE: 40% 260 on a Diet
ORIGINAL: Diablo-RCU
Here's some data to ponder. Putting down monokote on top of a piece of 1/16 inch balsa sheeting (light to medium density) increases the strength by 28-73%. Balsa has a tensile strength of 1.1-2.9 ksi, and monokote is 25 ksi.
Here's some data to ponder. Putting down monokote on top of a piece of 1/16 inch balsa sheeting (light to medium density) increases the strength by 28-73%. Balsa has a tensile strength of 1.1-2.9 ksi, and monokote is 25 ksi.
I had always geard that Putting down monokote on top of a piece of 1/16 inch balsa sheeting (light to medium density) increases the strength by 28-73%.
Ted, Everyone knows that the actual figures are 29.34 and 71.9886%
Monokote will not hold an improperly built plane together.
You can throw data around all you want but comon sense has to come into play at some point..
