Composite wings, any advantage ?
10-18-2011 | 01:24 AM
#26
My Feedback: (90)
RE: Composite wings, any advantage ?
ORIGINAL: DaveL322
My comment(s) regarding balsa/foam wings showing evidence of wear - I know more than a few reputable builders that replaced foam/balsa wings every 500 - 1000 flights because they would develop flex - spanwise and in torsion. No risk of them failing, but the planes would not groove as well in turbulence. No doubt building the wings heavier to begin with would extend the life expectancy. I really don't see a problem with designing/building to a given life expectancy for the benefit of lighter weight.
Regards,
My comment(s) regarding balsa/foam wings showing evidence of wear - I know more than a few reputable builders that replaced foam/balsa wings every 500 - 1000 flights because they would develop flex - spanwise and in torsion. No risk of them failing, but the planes would not groove as well in turbulence. No doubt building the wings heavier to begin with would extend the life expectancy. I really don't see a problem with designing/building to a given life expectancy for the benefit of lighter weight.
Regards,
10-18-2011 | 01:42 AM
#27
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From: Pescara, ITALY
RE: Composite wings, any advantage ?
The problem is the foam, that turns softer with use.
Unless you connect the upper and lower carbon strips with something solid and enough stiff (vertical grain balsa spar, for example), adding carbon strips is of little help and heavier.
Unless you connect the upper and lower carbon strips with something solid and enough stiff (vertical grain balsa spar, for example), adding carbon strips is of little help and heavier.
10-18-2011 | 05:38 AM
#29
Senior Member
RE: Composite wings, any advantage ?
ORIGINAL: nonstoprc
Could more carbon fiber cloth strips fix the span-wise flex developed later on? I know the common practice of building foam wings is to add two pieces as spars and one near the trailing edge. Maybe more strips should be used?
ORIGINAL: DaveL322
My comment(s) regarding balsa/foam wings showing evidence of wear - I know more than a few reputable builders that replaced foam/balsa wings every 500 - 1000 flights because they would develop flex - spanwise and in torsion. No risk of them failing, but the planes would not groove as well in turbulence. No doubt building the wings heavier to begin with would extend the life expectancy. I really don't see a problem with designing/building to a given life expectancy for the benefit of lighter weight.
Regards,
My comment(s) regarding balsa/foam wings showing evidence of wear - I know more than a few reputable builders that replaced foam/balsa wings every 500 - 1000 flights because they would develop flex - spanwise and in torsion. No risk of them failing, but the planes would not groove as well in turbulence. No doubt building the wings heavier to begin with would extend the life expectancy. I really don't see a problem with designing/building to a given life expectancy for the benefit of lighter weight.
Regards,
In my experience however, the construction technique that helps the most all around is vacuum bagging. I bag the wing panels, not the husks. The other thing I do that really increases strength is to take advantage of the socket. By building half span spars top and bottom surrounding the socket, and extending the spars to the skins, the structure forms an "I"beam. For the same weight or less than the false rib method, which only supports the socket and doesn't really reinforce much else, one can increase strength and stifness with minimal added effort and not really much weight increase at all.
BTW- the final word on this method hasn't been written yet either. I have built wing panels (around 500 squares) that weigh in at 8 ozs ready for finish. Silkspanning and painting adds another 3 ozs and servo and linkage another 2. That's the best I've done but there is room for improvement
FWIW2U
10-18-2011 | 10:52 AM
#30
My Feedback: (34)
RE: Composite wings, any advantage ?
ORIGINAL: TimBle
Sounds like a design problem, not a material limitation problem</p>
Sounds like a design problem, not a material limitation problem</p>
10-18-2011 | 01:15 PM
#32
RE: Composite wings, any advantage ?
ORIGINAL: Doug Cronkhite
.....We have the same problem with motorcycle helmets, which need to be replaced every 5 years due to the internal foam breaking down over time....
.....We have the same problem with motorcycle helmets, which need to be replaced every 5 years due to the internal foam breaking down over time....
10-25-2011 | 02:29 PM
#33
My Feedback: (2)
RE: Composite wings, any advantage ?
ORIGINAL: anders12
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
10-25-2011 | 10:51 PM
#34
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From: Pescara, ITALY
RE: Composite wings, any advantage ?
ORIGINAL: mithrandir
based on the several composite wings I have seen to date....
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
ORIGINAL: anders12
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
Simply because we already use the lightest materials available.
Plus, We have to deal with the "ding" resistance if the surface, that is already rather poor.
Try yourself to make one and you'll see.
The only area where it is possible to save weight is in the more accurate use of the resin quantity into the laminate and the gluing. It's all a matter of skill and time.
10-26-2011 | 04:59 AM
#35
RE: Composite wings, any advantage ?
One benefit to composite wings not mentioned here is the ability to (more easily) create non-standard wing planforms. I believe this was Chip's major motivation for his composite, semi-elliptical wings.
10-26-2011 | 07:32 AM
#36
My Feedback: (2)
RE: Composite wings, any advantage ?
ORIGINAL: Roberto B.
I'm Sorry, but what you say is wrong.
Simply because we already use the lightest materials available.
Plus, We have to deal with the ''ding'' resistance if the surface, that is already rather poor.
Try yourself to make one and you'll see.
The only area where it is possible to save weight is in the more accurate use of the resin quantity into the laminate and the gluing. It's all a matter of skill and time.
ORIGINAL: mithrandir
based on the several composite wings I have seen to date....
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
ORIGINAL: anders12
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
Simply because we already use the lightest materials available.
Plus, We have to deal with the ''ding'' resistance if the surface, that is already rather poor.
Try yourself to make one and you'll see.
The only area where it is possible to save weight is in the more accurate use of the resin quantity into the laminate and the gluing. It's all a matter of skill and time.
What I say is correct.... You don't know everything do you!!?? lol
I might point out the RC sailplane wings are not even cutting edge in construction and they have pretty low weights...
unfortunately.. my life is too busy now to prove I am correct....
10-26-2011 | 08:09 AM
#37
Senior Member
RE: Composite wings, any advantage ?
ORIGINAL: mithrandir
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
However, Bob Hunt and several other top CL guys routinely build 700 sq inch wings for CL models, finished in dope, that weigh in at 1 oz per 100 square inches. Not every one can do that and I'm not certain that ratio of weight to area will work in a free flying, heavier pattern model but it might. It will require open bays to achieve the weight but that's straight forward stuff
10-26-2011 | 01:43 PM
#38
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From: Pescara, ITALY
RE: Composite wings, any advantage ?
ORIGINAL: mithrandir
I have been in the composites business for a while....
What I say is correct.... You don't know everything do you!!?? lol
I might point out the RC sailplane wings are not even cutting edge in construction and they have pretty low weights...
unfortunately.. my life is too busy now to prove I am correct....
ORIGINAL: Roberto B.
I'm Sorry, but what you say is wrong.
Simply because we already use the lightest materials available.
Plus, We have to deal with the ''ding'' resistance if the surface, that is already rather poor.
Try yourself to make one and you'll see.
The only area where it is possible to save weight is in the more accurate use of the resin quantity into the laminate and the gluing. It's all a matter of skill and time.
ORIGINAL: mithrandir
based on the several composite wings I have seen to date....
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
ORIGINAL: anders12
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
A correctly designed and built all wood wing is lighter and stiffer than a foamwing and the compositewings seen in kits sofar.
As said many times, ''wood flies better!''
Anders J
Composite wings are heavier because they are simply not optimized. I doubt any of the composite ARF manufacturers actually employs an engineer to design the wing structure.
I could make a composite wing stronger and stiffer for the same weight as a foam wing....
Simply because we already use the lightest materials available.
Plus, We have to deal with the ''ding'' resistance if the surface, that is already rather poor.
Try yourself to make one and you'll see.
The only area where it is possible to save weight is in the more accurate use of the resin quantity into the laminate and the gluing. It's all a matter of skill and time.
What I say is correct.... You don't know everything do you!!?? lol
I might point out the RC sailplane wings are not even cutting edge in construction and they have pretty low weights...
unfortunately.. my life is too busy now to prove I am correct....
SO, I'm sure I have enough theoretical and practical skills to state what I'm saying. And I can prove it for example, saying that the fuselages I made for Sebastiano Silvestri's Look@me weighted less than 700gr, with canopies and painted in the mold.
http://www.rcuniverse.com/forum/m_97.../tm.htm#970061
Of course, all my comments are referred to the F3A world. I'm not into sailplanes.
02-06-2012 | 01:32 PM
#39
Member
RE: Composite wings, any advantage ?
<span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 16px; background-color: rgb(245, 245, 245); ">Airplane model Europa Pro Lt wing </span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 16px; background-color: rgb(245, 245, 245); " class="hps">weight</span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 16px; background-color: rgb(245, 245, 245); " class="hps"> is</span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 16px; background-color: rgb(245, 245, 245); "> </span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 16px; background-color: rgb(245, 245, 245); " class="hps">325</span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 16px; background-color: rgb(245, 245, 245); "> </span><span style="color: rgb(51, 51, 51); font-family: arial, sans-serif; font-size: 16px; background-color: rgb(245, 245, 245); " class="hps">grams<span class="hps">without</span> <span class="hps">the servo</span> . www.rc-composit.com</span>
05-20-2016 | 07:03 PM
#40
Senior Member
Agreed.....My Temptress balsa covered foam wings were built 8 1/2 years ago and are approaching 2000 flights, all either on glow or gasoline. Weights are low (around 13 1/2 ozs each for 500 squares par panel) and are fully painted. I hate monokote. Silkspan and dope finishes are just as light when done right, maybe even a tad lighter than MK or UK
To Ola's first comments, my light wings make for spritely performance throughout the flight envelope. On the design question, this wing design will do everything one wants including slow snaps or Dave L lightning fast snaps, and everything in between. Just a matter of set-up. Oh and they don't require 20 degrees of elevator throw for proper snaps and spins, but that's airframe design not just wing design
Center hinging is definitely better, more balanced, at least to me. There could be other factors affecting rolling results tho.
To Ola's original comments, foam composite versus molded composite, it depends.......to me foam/balsa composite is easier to build overall and is easier to control weight. And if you want to use 1/2 - 3/4 mm contest grade sheeting, the finished composite structure can be made strong and stiff with carbon veil. My holy grail of wing construction is a fully painted, 500 square inch panel whose RTF weight is less than 11 ounces. I think it's doable with either foam or built up construction
However, the final word has not been written on molded composite wing construction. An 11 ounce final weight RTF should be a little easier to actually build than the conventional technique. Molded wing makers are just not doing enough creative things with their lay-up. My 2 1/2 cents
To Ola's first comments, my light wings make for spritely performance throughout the flight envelope. On the design question, this wing design will do everything one wants including slow snaps or Dave L lightning fast snaps, and everything in between. Just a matter of set-up. Oh and they don't require 20 degrees of elevator throw for proper snaps and spins, but that's airframe design not just wing design
Center hinging is definitely better, more balanced, at least to me. There could be other factors affecting rolling results tho.
To Ola's original comments, foam composite versus molded composite, it depends.......to me foam/balsa composite is easier to build overall and is easier to control weight. And if you want to use 1/2 - 3/4 mm contest grade sheeting, the finished composite structure can be made strong and stiff with carbon veil. My holy grail of wing construction is a fully painted, 500 square inch panel whose RTF weight is less than 11 ounces. I think it's doable with either foam or built up construction
However, the final word has not been written on molded composite wing construction. An 11 ounce final weight RTF should be a little easier to actually build than the conventional technique. Molded wing makers are just not doing enough creative things with their lay-up. My 2 1/2 cents
I challenged myself to see if I could build sheeted foam and realize as much weight savings As with built up sticks. In this experiment I built a set of stab panels and did a few different things to them for lightness but with good strength. I was a little surprised when I weighed the 130 square inch panels after the carbon veil and Esaki paper were laid down. Much lower than expected at 44 grams per panel. These are the exact same design as the all wood stabs Delta is flying with now at 75 grams per panel. We'll see how these work in the rigors of flying over the next months.
Trying to get Delta's tail as light as I can so that I can change the APC heavy plastic prop to my new MDK hybrid that weighs less than half as much, a difference of about 3 ounces. That means no servos in the tail allowed. Sure they are easy but produce a heavy tail.
05-26-2016 | 06:04 PM
#41
Senior Member
The foam stabs finished at 65 grams a piece, all paint. Esaki and dope builds a stressed skin that should be plenty strong for a stab. Paint added about 20 grams a panel. The typical ultra kote weighs about 70 grams per yard so paint weight build up is similar to the typical ultra kote.
