If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#32
|
|||
|
|||
Robert Little wrote:
One other thing, though. The use of epoxy or polyester resin combined with glass again starts the deterioration clock. The glass is permanent, but the resins are what age so quickly in the presense of UV radiation. Old fiberglass boats look rough after a few years and will burn like gasoline. The glass does not age and will be the big mess left after the fire since it does not burn. Our process doesn't use any resins as one usually assumes when glass is mentioned. The "temporary cellulose" base dope is used to fill and tauten only. It can burn off but the glass will remain in place with little to no loss of strength to the fabric. The late Bill Hale always used our fabric on his acrobatic aircraft due to the glass acting as a fire wall to the occupant. Many NASA experimental windmill and wind tunnel blades have been covered with our glass as well. Robert, you're starting to sound like a very bad salesman, creating dark ghost where everyone else sees daylight. Epoxy is not a vampire that burst into a cloud of dust if the blinds are raised. In fact, the proper formulation can sit in the sun for years without measurable effects. I personally plan to take the very unusual step of painting my airplane to keep it from rotting away in the sun. Where are these people who don't paint their aiplanes after having paid to get them covered? Furthermore, if my elevons catch on fire then I will have been burned to death long before. A quick look at the Delta planform will explain why. But this begs the question of, "If the FG can take the forces and stresses of flight without the butyrate without excessive deformation, then what is the point of the butyrate?" Didn't you say the glass was glued on with the butyrate? If it's not necessary, why not just tie on the FG cloth, spray a coat of paint or two, and go flying? That is not a redundant question or a taunt. I am really trying to understand the role each of the parts play in your system. I want enough information to know if I can apply your product, or a variant of your product, to my situation. I have a firewall already, and I don't need a windmill or wind tunnel. I need a very light elevon. On a more serious note, I think I called you Richard in another post. Do you have practice kits available? -- http://www.ernest.isa-geek.org/ "Ignorance is mankinds normal state, alleviated by information and experience." Veeduber |
#33
|
|||
|
|||
On Thu, 15 Apr 2004 19:00:06 GMT, Ernest Christley
wrote: wrote: Ernest, did you miss this post by Robert Little? See below, it explains how taught the fabric is. Corky Scott Once installed correctly, it has a much stiffer surface than the more flexible and stretchy dacron. I have seen many pictures on the covers of aviation magazines that show the top of the wing with pillows deforming between the ribs as the fabric stretches under the aerodynamic load of flight. Properly installed glass fabric does not stretch and will remain closer to the profile of the ribs than any other covering short of metal. Many of our customers comment that our fabric has gained them real increases in airspeed beyond the fact of being covered with a fresh finish. This also allows your paints to last longer as the flexing really stresses the surface coatings. Plus, you don't have the worry of falling through it if you should mis-step on a low wing. You can walk on it as long as the rib underneath it can handle the weight. Robert Little Guys, either I'm missing something here or I'm just not smart enough to get my mind wrapped around it. How is the FG stretched tight enough to make it stiff? Is the butyrate a hard substance once it dries/cure/whatever-butyrate-does? Is the following statement correct? If there is any looseness at all in the fabric, and it is pulled tight by the dope, then the dope is what will carry the stress, not the fabric. If the butyrate is carrying the stress, then would this system be any stronger that chopped strand composites? Yes. It is true. I do NOT know what I'm doing. But I will before I'm done! Ernest, it isn't the dope that provides the strength, not with Razorback fabric or with any fabric. The fabric itself is what gives the wing it's strength and/or stiffness against the wind. The initial application of the correct dope, in the case of the Razorback fabric, or a calibrated heating iron, in the case of the Polyfiber fabric, is what shrinks it. The application of paints on top of the fabric serve to protect it from UV rays, make it waterproof, and look nice, but do not add strength. You should participate in one of Ron Alexander's fabric covering sessions and see for yourself how it's done. They offer hands on experience and you learn how to properly apply fabric to wings and control surfaces. You will discover that the fabric is incredibly taught, once properly shrunk. The skin of a drum comes to mind. You can shrink the fabric too much and actually crush or bend the framework beneath it, the fabric has that kind of strength. Corky Scott |
#34
|
|||
|
|||
wrote:
Ernest, it isn't the dope that provides the strength, not with Razorback fabric or with any fabric. The fabric itself is what gives the wing it's strength and/or stiffness against the wind. The initial application of the correct dope, in the case of the Razorback fabric, or a calibrated heating iron, in the case of the Polyfiber fabric, is what shrinks it. The application of paints on top of the fabric serve to protect it from UV rays, make it waterproof, and look nice, but do not add strength. You should participate in one of Ron Alexander's fabric covering sessions and see for yourself how it's done. They offer hands on experience and you learn how to properly apply fabric to wings and control surfaces. You will discover that the fabric is incredibly taught, once properly shrunk. The skin of a drum comes to mind. You can shrink the fabric too much and actually crush or bend the framework beneath it, the fabric has that kind of strength. Corky Scott Corky, the polyester fabrics have long chain molecules that 'curl up' when you heat them. This makes the actual threads shorter, so that after the actual fabric is shrunk to size. The butyrate doesn't shrink the fiberglass threads. It just grabs a couple and pulls them closer together. "Chain is only as strong as its weakest link" comes to mind. Until a butyrate coated covering stretches enough to take out the slack that was there when the fabric was first put on, it is only being held together by the butyrate. That is the mental picture I have. I could be wrong, and I don't even know if it is good or bad. For starters, I don't know how strong butyrate dope is. It could be much stronger than polyester, and just needs the fabric to give it some shape. I'm in unknown territory and just need a compass and a map, or maybe just a practice kit to play with. Didn't I read somewhere that butyrate dope can be found in most hardware stores under a different name? -- http://www.ernest.isa-geek.org/ "Ignorance is mankinds normal state, alleviated by information and experience." Veeduber |
#35
|
|||
|
|||
Didn't I read somewhere that butyrate dope can be found in most hardware
stores under a different name? Reminds of my childhood... made a few of those gawdawful to make model airplanes made with 10 million sticks of blasa wood, glue, and tissue paper... Then there was the process of doping it shrink the tissue paper... Had a friend.....he didnt use dope on his....he use spray on starch (you know the kind for ironing your clothes)....seemed to work pretty well....never did find out if that was some insider secret or not.....asked how he knew and he said it just seemed like it would work to him! take care Blll PS...no Im NOT saying use spray on starch on a real airplane |
#36
|
|||
|
|||
|
#37
|
|||
|
|||
On Fri, 16 Apr 2004 21:08:23 +0800, Stealth Pilot
wrote: Ernest, it isn't the dope that provides the strength, not with Razorback fabric or with any fabric. The fabric itself is what gives the wing it's strength and/or stiffness against the wind. The initial application of the correct dope, in the case of the Razorback fabric, or a calibrated heating iron, in the case of the Polyfiber fabric, is what shrinks it. Corky Scott you surprise me cobber. mistakes like the one contained in the paragraph above are what led to Steve Wittman's death. in the case of cotton, irish linen, razorback and any of the non shrink fabrics it IS the dope which causes the fabric to tighten as the solvents evaporate from the dope. Stealth, what are you smoking? That's what I said. Here's my sentence: "The initial application of the correct dope, in the case of the Razorback fabric, or a calibrated heating iron, in the case of the Polyfiber fabric, is what shrinks it. Now you say: in the case of cotton, irish linen, razorback and any of the non shrink fabrics it IS the dope which causes the fabric to tighten as the solvents evaporate from the dope." But you are just repeating what I said. Did you read it a bit too quickly? Corky Scott |
#38
|
|||
|
|||
In charles.k.scott@
dartmouth.edu wrote: On Fri, 16 Apr 2004 21:08:23 +0800, Stealth Pilot wrote: Ernest, it isn't the dope that provides the strength, not with Razorback fabric or with any fabric. The fabric itself is what gives the wing it's strength and/or stiffness against the wind. The initial application of the correct dope, in the case of the Razorback fabric, or a calibrated heating iron, in the case of the Polyfiber fabric, is what shrinks it. Corky Scott you surprise me cobber. mistakes like the one contained in the paragraph above are what led to Steve Wittman's death. in the case of cotton, irish linen, razorback and any of the non shrink fabrics it IS the dope which causes the fabric to tighten as the solvents evaporate from the dope. Stealth, what are you smoking? That's what I said. Here's my sentence: "The initial application of the correct dope, in the case of the Razorback fabric, or a calibrated heating iron, in the case of the Polyfiber fabric, is what shrinks it. Now you say: in the case of cotton, irish linen, razorback and any of the non shrink fabrics it IS the dope which causes the fabric to tighten as the solvents evaporate from the dope." But you are just repeating what I said. Did you read it a bit too quickly? I spoke with my instructor at the A&P school again and he was pretty adamant that the main shrinking agent with the natural fibers was water. The tautening effect of the dope is actually a negative if you put it on too thick. I did misunderstand him, however, as far as the cause of the sagging razorback in cold weather. He said it isn't so much caused by the underlying frame contracting, and didn't think that would be a noticeable problem with a steel frame. He claims that there is a definite issue with the stuff in cold weather that can't be explained as poor application technique. Mind you, I am just passing this along. I would personally like to see some testing done, and would be interested in leaving a small test frame covered with each major process outside in my backyard over the winter. It often gets down to 20 below or so around here so it would be a valid test. ---------------------------------------------------- Del Rawlins- Remove _kills_spammers_ to reply via email. Unofficial Bearhawk FAQ website: http://www.rawlinsbrothers.org/bhfaq/ |
#39
|
|||
|
|||
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Fabric covering processes | Jerry Guy | Home Built | 2 | January 29th 04 06:49 PM |
Fabric Work | Doug | Home Built | 9 | January 26th 04 03:31 AM |
fabric and tube by the ocean. | Ed Bryant | Home Built | 5 | December 6th 03 07:00 PM |
Soliciting Testimonials on Covering Systems | Larry Smith | Home Built | 5 | August 18th 03 09:24 AM |
Glass Goose | Dr Bach | Home Built | 1 | August 3rd 03 05:51 AM |