Floorboard Material / Installation

lsa140

lsa140

Plans Built Bearhawk LSA
I'm curious to hear what fellow builders are using for floorboards in their Bearhawks? The LSA plans show several different thicknesses of aluminum. I've seen plywood, carbon fiber, or aluminum used in cubs. I read in a forum that someone had used some small beads of silicone between the aluminum floorboards and 4130 tubing to successfully eliminate some of the noise and vibration. Each material seems to have it's own set of pros and cons. Thoughts?
 
Some I gathered some facts about flooring for the Patrol (22.25 sq ft area), and considered 1/4" Baltic Birch, Composite Flooring, and Aluminum.

-A Baltic Birch floor would weigh 19.58 pounds.
-A composite Floor 1/4" 2 ply from Javeron would weigh 10.23 pounds
-An Aluminum floor of .032 weighed 10.26 pounds.
-An aluminum floor of .025 weighed 8.01 pounds
-Installing .020 under the rear seat between station D-E with .025 AL in the rest of the floor weighed 7.64 pounds.
-Istalling .016 between D-E would save another .3 pounds. over .020 AL.

I did not think of noise reduction with silicone, but I thought of Cork, which does not absorb water.

Some would argue that Aluminum is inferior due to noise and other factors. Cessna, Beech, and Piper used a lot of Aluminum and no one complains too much.

Aluminum does not make noise unless it vibrates, but neither will it suppress noise on its own. To add suppression of noise from other producers like exhaust would add .15 pounds per Sq Ft. if I used Sound Proofing Mat from www.supersoundproofing.org So, I thought that product was pretty light and will consider installing it.


It surprised me that I could save 12 pounds by not installing wood, and that Aluminum compares favorably with Composite Flooring for weight savings.

Brooks Cone
Patrol #303
 
An A&P I know does a lot of work on Pacers. On customers planes that are concerned about noise he will coat the bottom side of the aluminum floor with basically truck bed liner, something like roll on Rhino Liner. Says it works good to reduce noise.

I'm installing 0.032 aluminum flooring in my BH. Someday I'd like to replace it with carbon fiber but I'm not sure that will ever happen.
 
It's tough to beat aluminum for floorboards. Like Whee I'd like to do mine in carbon fiber but for now I'm using the aluminum ones my kit came with. In all likelihood I'll never change them.
 
I have an 18.5' canoe made of Kevlar/resin. The entire canoe with seats and aluminum add-ons weighs only 48#

The Kevlar is tough, so thin you can almost see thru it,. I've thought of using something similar on my Patrol. And my canoe it is really quiet :)
 
I've used .032 aluminum and it has held up well. The baggage compartment divider was noisy until I put that black, tar like, sticky back noise deadening material on it. You don't need to cover it, just apply small pieces in various places until it quiets down. The floor doesn't make noise when the rear seat is in. When the seat is out I lay a piece of egg crate foam on the floor which does the trick. It also serves as an emergency sleeping pad if I need to sleep in the plane.
 
I think if you can hear the floor boards rattling, then restarting your engine will be a higher priority. JK

I have aluminum flooring and its never crossed my mind that they could feasibly make enough noise to hear over the engine. You would need a lot of insulation and a great muffler... That said, I have a lightweight marine carpet over top. Even with a spartan interior like mine, bare alloy is a step too far. Carpet looks great and has lots of practical advantages.
 
Brooks, thank you for sharing this information, what a great reference. It looks like the LSA has just over 18 sq ft of area.
 
wheeZzz I've also seriously considered using carbon fiber, but the additional cost and availability has me leaning towards aluminum.

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Battson said:
I think if you can hear the floor boards rattling, then restarting your engine will be a higher priority. JK

I have aluminum flooring and its never crossed my mind that they could feasibly make enough noise to hear over the engine. You would need a lot of insulation and a great muffler... That said, I have a lightweight marine carpet over top. Even with a spartan interior like mine, bare alloy is a step too far. Carpet looks great and has lots of practical advantages.
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Well said, though my little C-85 probably doesn't quite match the sounds output of your 540:) Even though the engine produces the dominant noise, vibrating aluminum can still contribute to the noise level in the cabin. The post I read (can't remember where) said that adding the silcone between the tubing and aluminum produced a thud when impacting the floor, as opposed to a metalic rattle of aluminum vibrating against the steel. I'm interested in using some type of thin weather stripping tape stuck to the bottom of the aluminum floor, layed out on tubing centers.

Battson is your carpet fastened or glued down, or just laying on top of the aluminum floor?
 
Battson said:
I think if you can hear the floor boards rattling, then restarting your engine will be a higher priority. JK
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Ouch! Do you know how much it hurts when you snort hot coffee through your nose? This made me laugh (and yell "Ow! Ow! Ow!") so much that my wife came to see what the heck was wrong with me...
 
lsa140 said:
Well said, though my little C-85 probably doesn't quite match the sounds output of your 540:) Even though the engine produces the dominant noise, vibrating aluminum can still contribute to the noise level in the cabin. The post I read (can't remember where) said that adding the silcone between the tubing and aluminum produced a thud when impacting the floor, as opposed to a metalic rattle of aluminum vibrating against the steel. I'm interested in using some type of thin weather stripping tape stuck to the bottom of the aluminum floor, layed out on tubing centers.

Battson is your carpet fastened or glued down, or just laying on top of the aluminum floor?
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Yeah that is the difference, when the engine is at low idle on a steep approach, I used to hear some things rattle. To be specific, at certain RPMs I hit a natural frequency node of the alloy sheet I used for the aft bulkhead. If I don't have noise cancelling headphones on (which is never these day), then I can hear it rattling.

The other thing I hear, particularly if I descent from up him down into a warm weather pocket near MSL, is the alloy panels which make up the wing tanks "popping out" (like drumming, except it only happens once!). It used to worry me, until I got used to it.

For the carpet, I used the same screws which hold down the floorboard to secure the carpet. Always looking for those little simplifications.
 
Battson said:
Yeah that is the difference, when the engine is at low idle on a steep approach, I used to hear some things rattle. To be specific, at certain RPMs I hit a natural frequency node of the alloy sheet I used for the aft bulkhead.
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That's the same thing I experienced. It can be quite loud but it certainly isn't louder than the engine. Because one of my kids is going to be sitting right next to the bulkhead I'd like to eliminate that noise.
 
lsa140 said:
I'm curious to hear what fellow builders are using for floorboards in their Bearhawks? The LSA plans show several different thicknesses of aluminum. I've seen plywood, carbon fiber, or aluminum used in cubs. I read in a forum that someone had used some small beads of silicone between the aluminum floorboards and 4130 tubing to successfully eliminate some of the noise and vibration. Each material seems to have it's own set of pros and cons. Thoughts?
Click to expand...

I bought 1/8" by 1" wide, 10' long felt. Cut 1/2" wide, applied spray adhesive to one side. Glued to all the tubing under the floor. 2024T3 .032" thick load bearing areas, .025" under the front seats.
Mark M.


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Battson said:
Yeah that is the difference, when the engine is at low idle on a steep approach, I used to hear some things rattle. To be specific, at certain RPMs I hit a natural frequency node of the alloy sheet I used for the aft bulkhead. If I don't have noise cancelling headphones on (which is never these day), then I can hear it rattling.

The other thing I hear, particularly if I descent from up him down into a warm weather pocket near MSL, is the alloy panels which make up the wing tanks "popping out" (like drumming, except it only happens once!). It used to worry me, until I got used to it.

For the carpet, I used the same screws which hold down the floorboard to secure the carpet. Always looking for those little simplifications.
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Is that popping caused by the small fuel cap vents not being able to keep up with the outside air pressure change? Great idea using the floor fasteners to hold the carpet as well.
 
whee said:
That's the same thing I experienced. It can be quite loud but it certainly isn't louder than the engine. Because one of my kids is going to be sitting right next to the bulkhead I'd like to eliminate that noise.
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Any good ideas on better materials for that bulkhead - weight saving materials which can't rattle are of most interest! Some kind of plastic maybe? A bare carbon fibre panel perhaps?? ($$$ Ching Ching)
 
I don't have any really good ideas. Plan A: Have my brother layup a carbon fiber sheet. He used to do carbon fiber work at Boeing and said it would be really easy but I know he is really busy with work and his family. Plan B: Layup and paint a fiberglass sheet. Plan C: Aluminum with some foam glued to the back. Think I'd use that foam all the guys on BCP are using on their Cessna rebuilds.

I wonder how Kydex would work. Mark M used it on his Pacer and the pics look great.
 
whee said:
I don't have any really good ideas. Plan A: Have my brother layup a carbon fiber sheet. He used to do carbon fiber work at Boeing and said it would be really easy but I know he is really busy with work and his family. Plan B: Layup and paint a fiberglass sheet. Plan C: Aluminum with some foam glued to the back. Think I'd use that foam all the guys on BCP are using on their Cessna rebuilds.

I wonder how Kydex would work. Mark M used it on his Pacer and the pics look great.
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Do you recall what that foam was called?
 
I don't know what the foam is called. They buy it from Selkirk in either 1/4" or 1/2" thick sheets.
 
Yes, I looked into fibreglass for the baggage tube and aft bulkhead panel.
I found I could save 50% the weight vs alloy, in the best case - but I am sacrificing strength so the weight saving it's really that much. Plus it's a lot more expensive and doesn't look as good.
The saving hasn't yet convinced me to "get around to it". I should though.
 
Battson said:
Any good ideas on better materials for that bulkhead - weight saving materials which can't rattle are of most interest! Some kind of plastic maybe? A bare carbon fibre panel perhaps?? ($$$ Ching Ching)
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Maybe rivet a couple stiffeners on the existing bulkhead and bond some vinyl fabric to the aluminum?

I built a boat that used quite a bit of 1/4" okume marine plywood. It was rigid for it's thickness, easy to find local, affordable, and quite a bit lighter than the baltic birch a lot of people use for floor panels. Looks like a 4'x8' .032 2024 weighs around 15lbs. 5 ply 3/16" Okume plywood weighs around 16lbs per 4'x8' sheet. You could possibly use 3m super 77 to bond some lightweight vinyl fabric to it, wrap the edges around to the back and staple.

I'm planing on some type of fabric. Possibly with a couple zippers to access rear baggage. (sleeping bags, etc)

I've considered using 3/16" okume for the floors with a thin carbon fiber cloth epoxied on top.
 
On the Kydex. Couple four reasons for choosing it over aluminum or pre made fancy pants and plane ole fabric in areas that will see abuse. One if Kydex is scratched by a sharp object, the scratch can be removed with heat gun. It'll take abuse from something bouncing against it and maintain its shape...mostly. With aluminum sheeting, each and every dent will remind you of what caused it....kydex is lighter than aluminum and easier to form. Can use particle or plywood forms to shape with either heat or pressure. Bend with a pan or leaf brake with a generous radius. And it loves bead rollers. The attached picture shows what can be done by a first timer. The panels are made from .028" is areas that will not see abuse...under the threshold. Everywhere else is .040"
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In this picture the .028" covers the flap and aileron cables in the overhead. The fuel line covers are made from .032" 6061T6
1fed2f6f7f5fc09c8d1e4cfb449ef38b.jpg

Rear seat an cargo area is covered in .040" above the cargo area is fabric
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For reference - the worst that our fabric has sustained are rubs in the paint, and the soft 5052 Al I've used hasn't been dented yet.

Apart from the need to access the aft fuselage for the 100hr inspection, there would be no need for a removable aft bulkhead at all, and just light fabric would suffice.
 
Wow Mark, that kydex interior looks great! As for what I came up with for the floorboards, I'm doing a quick build so it came with aluminum floorboards so my only dilemma was what to cover them with. I didn't want to paint them because the paint always wears off. Didn't want carpet because I will be using this off airport a lot and it will get mud inside occasionally so I eventually decided to go with roll on bed liner. Durable, fairly light (compared to carpet) and I expect to get some sound dampening from it.
 
I vacillated on the floors...paint, no paint...carpet, no carpet and the rubber floor stuff. Did paint both sides of the floor boards with the green rattle can anticorrosion paint. When I disassembled the airplane..the 64 year old flooring that was painted with the anticorrosion paint had zero corrosion. Flooring without paint...corrosion on the under side. The pilot copilot area Kydex to floor intersection is joined together with angle strips of 0.32". Pop riveted to the Kydex with aluminum backer strips, then attached using the same screws for the floor. My goal is also to prevent dirt and mud from migrating to the crevasse where the fabric wraps around the lower longeron. Did go with carpet, carpet will keep the dirt and mud more or less where it was deposited. The carpet is the really light stuff from national airplane parts association. Cleaning after a back country adventure shouldn't be a big deal....I have a commercial carpet machine with the upholstery attachment for the Bearhawk motel. The passenger and small cargo area carpet and Kydex/rudder cable covers are overlapped at the floor, secured with the same screws for attaching the floor to the structure.
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Battson said:
Any good ideas on better materials for that bulkhead - weight saving materials which can't rattle are of most interest! Some kind of plastic maybe? A bare carbon fibre panel perhaps?? ($$$ Ching Ching)
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I was planning on using fabric that is attached with snaps wherever there is an attach tab on the fuselage. I figured the heavy baggage will be strapped down and with snaps around the edges and on the middle "v" structure, it would be enough to prevent stuff from falling into the rear fuselage and would be the lightest option of all.
 
nichzimmerman said:
I was planning on using fabric that is attached with snaps wherever there is an attach tab on the fuselage. I figured the heavy baggage will be strapped down and with snaps around the edges and on the middle "v" structure, it would be enough to prevent stuff from falling into the rear fuselage and would be the lightest option of all.
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That's what we did on our Luscombe. It worked well; no baggage ever got into the aft portion of the plane. One reason I don't think we are going to do the same on the BH is because there was always a draft that came from the back of the plane and I think a solid barrier would have help eliminate it.
 
I came across in my notes a Supplier of composite material that may be useful for flooring if one has unlimited funds available. (Their look is at the bottom of the post.)

Comparing it against other options demonstrates the extras cost involved at making improvements beyond a certain point. I have no information on strength or durability of the product except for the manufacturers description of it being of "Strong and light" I am just passing along some reference information I have in my notes.

Their 1/4" 1 ply honeycomb sandwich product uses one layer of 8 oz fiberglass over the honeycomb core. The weight of a Patrol floor made with this would be 6.26 pounds, saving 4.0 pounds from a very durable floor made of .032 Aluminum.

The cost today for a 4x8' sheet (enough for the floor of a Patrol) is over $600 , plus shipping. I think a Patrol rear bulkhead could use a 2x4' piece for $270, but the Four Place builders would be looking at 4x4 for $416.

https://www.acpsales.com/Fiberglass-1-Ply-Honeycomb.html
 
I have some of the ACP Composite panels and they are a very attractive option for flooring. Attractive until I look at the cost.

From my experience in auto racing, I would not use carbon fiber any where in the cockpit. In a crash, carbon fiber panels fracture into razor blade like fragments. The physical properties that make carbon fiber so attractive as a panel material also make it lethal in a crash. The laminates tent to separate into chards of .010 thick razor blades with very fine needles on the edges. The stuff is really dangerous to handle once damaged.

I am planning on using aluminum with "Hush Kit Material from Vantage Plane Plastic (www.planeplastics.com).
 
I have been thinking about applying a layer of helicopter tape to the floor boards where they contact the tubing of the fuselage. I think this will help a lot with noise and protect the finish on the tubing from damage due to the panels abrading the painted surface. The tape would be in addition to the sound damping foam that I would use. I am using 032 aluminum floor boards where feet or cargo can be located. Under the front seats I am using .025.
 
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bergy said:
I have an 18.5' canoe made of Kevlar/resin. The entire canoe with seats and aluminum add-ons weighs only 48#

The Kevlar is tough, so thin you can almost see thru it,. I've thought of using something similar on my Patrol. And my canoe it is really quiet :)
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Not a bad thought. I built a 20' cedar strip canoe that's fiberglassed over and then has some reinforcing patches on the bottom.

It's taken a bunch of beatings, including my brother losing it off the roof of his truck at 55mph, and nothing worse than some abrasions which were easy enough to fix.
 
For those that wanted to add some "no slip" to their aluminum floorboards, there is a product called Loncoin that is used for all kinds of purposes, including aircraft (Boeings, King Airs, Bonanzas).

If you've been on an airliner lately you've walked on it and probably didn't even know it...it is also called "coin mat".

The stuff comes in various sizes, colors and thicknesses. For example the stuff used for general aviation is 2mm/.0787" thick PVC and .7 lb/sq' and comes in 12 colors. A little heavy but if you needed the baggage bay with a little more durability or easier to keep clean...might be an option. Tough stuff and if you shop around you can find it for under $5 a square foot. The make thinner/lighter stuff...

Wyo Johnson
1423B
 
Just a thought on floorbds: If you overlap the edges of the various sheets of floorbds, remember to make the sheet above the landing gear struts easily removable so you can access the top bolts on the landing gear struts. I can access those bolts from below but it requires removing a multitude of machine screws.

Jim Douglass
 
I haven’t been planning to put anything over our aluminum floorboards. Battson has mentioned several times that carpet is nice because it traps dirt and helps keep it out of the belly. That sound like a good idea. I looked at that coin mat stuff a while back and really like how it looks but it isn’t going to trap dirt. We put a lip on our floor boards to keep stuff from getting into the belly and I think it will work.

Saturday I was installing the rear seatbelts and dropped a wrench which dented the floor board😡 Guess I’ll be installing carpet now...
 
Has anyone done weight and performance comparisons on various carpet options that can be ordered online? I don't know the first thing about that stuff including sources.
 
I have used a marine vinyl product that Jared recommended. That manufacturer appears to have gone out of business but I bet there is something else similar out there. Very light. Glues down with contact cement. Cleans up easily. Mark
 
Mark Goldberg said:
I have used a marine vinyl product that Jared recommended. That manufacturer appears to have gone out of business but I bet there is something else similar out there. Very light. Glues down with contact cement. Cleans up easily. Mark
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That has been some great stuff, called Deco Dot and sold by Nautolex. It has held up very well and is much lighter and thinner than the coin mat type of product. I don't know of anyone still selling it, but asking a marine upholstery place would be a good start.
 
I also used the Deco Dot material after looking at Marks LSA. I found surplus material at a fabric supplier and purchased all of one color that he had. Sold partial to a Patrol builder and plan on lining my tool box drawers with the remnants. At the time I purchased it the supplier had one or two other colors in stock but that was over two years ago. If interested might be worth a call, the price was very good as it was discontinued product. https://www.yourautotrim.com/
 
I just finished cutting 1/4" Baltic Birch for the floorboards underneath the seats of my Patrol and by the rudder pedals. I continued to use aluminum in the baggage compartment. The weight penalty in my Patrol was 3.2 lbs vs using aluminum throughout. I will easily make that up by making custom stringers out of wood vs the aluminum ones that come with the kit which are a bit heavy. My thoughts on the floor when I sat in a Patrol and flew it at Oshkosh was that I didn't like the oil canning from the floorboards. When you look at a Cessna floor installation there are considerably more stiffeners to overcome that issue. I just finished varnishing the Baltic Birch and it looks really handsome. Wood will also do a lot to dampen noise and vibration.
 
If I was going to use aluminum I think I would put a bead every 4-6 inches to stiffen it. There are some light poplar and Okoume plywoods that would weigh about the same as the .032 aluminum. I have used lots of Okoume before. I would use 4mm where you step, 3 mm where you don't. Okoume is usually sold as a marine plywood.
 
1/4” Baltic is actually 6 mm thick the 4 Okume would weigh less but be sure you get true Marine Grade as the Big Box version is typically a Chinese knockoff, not voidless and with much thinner face veneers.
 
For everyone using aluminum, what are you putting on for corrosion protection that will also take the abuse of feet/stuff slid on it all the time?
 
zkelley2 said:
For everyone using aluminum, what are you putting on for corrosion protection that will also take the abuse of feet/stuff slid on it all the time?
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The area forward of the front seats is bare in my case, and the sliding feet seem to keep things pretty well polished.
 
The "Dot" mat is extremely durable and will protect the aluminum from dents, etc. I've seen people drop tools and it not damage the honeycomb floorboards underneath...which are fragile on a good day!
 
Anyone wanting to use thicker material keep in mind you'll need to raise the rudder pedals and control column to clear it. This also necessitates modifying the flap quadrant guide and the upper attach arms for it, raising the control column causes the elevator bushing to interfere. I just bent mine up out of the way and opened up the hole on the quadrant piece a little.
 
I made mine from aluminum. If starting now I would go with a carbon/foam composite. I believe 1/8 foam would work, wouldn't be lighter than the aluminum, but much quieter. I had intended to use the deco dot material on the aluminum but didn't buy it quick enough. My floorboards include an upside down channel at the edges to cover the rudder cables.
 
I used the aluminum Mark supplied with my kit and coated it with marine deck paint made for aluminum boats. I think the supplier was Jamestown Distributors. It seems tough and survives me taking the floors out and back in. Was easy to do with a roller. I has a little gloss and nonskid, but not sand.
 
1/4" Nomex sandwich panel interfered with both on my kit. The rudder pedal tubes and control stick rubbed when articulated, particularly the control stick hardware. I don't see how it wouldn't interfere.

ETA: I forgot by design the floor stops short of the rudder pedals. I extended mine forward and therefore have this issue there, the control stick would cause problems regardless.
 
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Rod,

I work on composites on aircraft...it's really not a great material for floorboards as it is damaged easily and mounting in the Bearhawk creates a lot of re-think on mounting. They use is in large commercial aircraft but the panels are .5 - .75" thick...and are covered with carpet to stop high heels and wrenches from denting them.

I think dot mat or the roll on deck/bed liner would work well but the roll on stuff would have to be looked at for fire/smoke off gassing I would think.

Andy
 
Some of the Cub re builders in Alaska are using carbon flooring. I don't know exactly what it is but I have seen a video of installation, it's quite flexible and they cut it to fit with a pair of shears. I tried to contact the company making it in Wasilla but never got a reply.
 
Carbon can be a bear to work with, and dangerous in some aspects. I still have a shard of carbon in my hand from building B-2's that the doc's can't find on X-ray or radar (no joke)...and it's deep enough, it hasn't worked it's way out (1999)! The dust from sanding or grinding will kill you.

carbon is brittle and fractures like window glass...into long spears, but some hybrids "glass/carbon" minimize that. Glass will actually take for heat and abuse than carbon.

There is a manufacturer called Vectorply that weaves some great stuff...a good supplier for small batch stuff is Composites One.

Andy
 
Dennis’s and I used the aluminum provided with the kit for everything except the floor under our feet and it is the lightest wood we could find. I think it is a 5 ply birch. I put a layer of aluminum backed bubble wrap under the floor and we put nut plates in and screwed them down. Dennis did not use the bubble wrap and we both have carpet with a 1/4 inch thick Cotten fabric insulation underneath. Could have done without the bubble wrap as you can’t hear or feel any difference. I believe the wood under our feet gives a stronger feel than the aluminum but you’d have to ask someone with aluminum.
 
Wyo Johnson said:
Carbon can be a bear to work with, and dangerous in some aspects. I still have a shard of carbon in my hand from building B-2's that the doc's can't find on X-ray or radar (no joke)...and it's deep enough, it hasn't worked it's way out (1999)! The dust from sanding or grinding will kill you.

carbon is brittle and fractures like window glass...into long spears, but some hybrids "glass/carbon" minimize that. Glass will actually take for heat and abuse than carbon.

There is a manufacturer called Vectorply that weaves some great stuff...a good supplier for small batch stuff is Composites One.

Andy
Click to expand...

Andy, thanks for the heads up on the hazards
 
I bought some carbon and some kevlar. I have used a little carbon before, but never kevlar. I was a little surprised at how little stiffness 1 layer of 5 oz kevlar has. My cargo bulkhead is laminated but not cut. I have started on the cargo floor. They are a pretty low priority as I can use the aluminum that came with the kit, and replace them later.

The cargo floor will be strong, as will the places where passengers step. The rest can be lighter. I am using 1/8" core, and mostly CF cloth. Where pax step, I also use a layer of kevlar for toughness.

Yeah, no sawing or sanding, but 5 oz cuts really easy with scissors, and you can cut 2 or 3 layers with better shears, and by that I mean after it is impregnated with epoxy and cured.

To make them easier to install, I laminate the top to the core, then cut about 1/4" of the core out, down the middle for and aft. When I laminate the bottom I will leave a strip 1/4 - 3/8 down the same line without epoxy. Sort of a 1 way hinge. It will flex a bit so you can bend it to make it easier to install.

Flat laminations are pretty easy. I do it on an old piece of glass on a workbench. Each lamination might take me 20-30 minutes, as time permits.

With a little added kevlar for the high traffic areas, they should weigh just about exactly half of the .032 aluminum. I weighed some finish laminates and they weigh what they should. I hope they hold up, but they are non-structural.
 
No worries Marcus...the world doesn't need a bunch of dead Bearhawk builders.

Svyolo, good call on the Kevlar, hazmat wise its pretty bad stuff. Certain types of it cause cervical cancer, they used to warn us about not washing our clothes with the rest of the family, etc. Cured lessens the problem but sanding/grinding makes the fibers airborne. I see these Honda racer kids grinding on Carbon and Kevlar parts like its a fiberglass part...bad news.

MSDS (Material Safety Data Sheet) will have all the warnings...you can find em online from the manufacturer/vendor.

If builders are looking at doing composites, a Robin Air vacuum pump can be used to vacuum bag the laminates...it helps squeeze out excess resin (if you use the appropriate breather and peel ply)...the finish looks great and the more resin you get out of a part the stronger/lighter it is. If you look up the wood worker websites where they are doing veneering...they have pressure switches etc. for about 1/4 of the price of the composite sales websites. Kinda like if you have a Cadillac and a chevy and just ask the parts store for a part number instead of asking for the Cadillac part!

Airtech supplies all the bagging stuff...and are aerospace grade but at real prices.

Andy
 
I think a "School me" thread on this topic with photos, supplies and suppliers would be worthy of a sticky.
 
I remember reading somewhere that one of the big chopper mfg. (bell ?) has some type of thin adhesive sound absorbing foam which they put on the inside of the skins to
stop the ambient noise from fatiguing the skins. I think it would quiet the inside well if it absorbs skin vibration.

I was experimenting a while back with a composite-- it was a layer of blue foam with a sheet of .015 aluminum glued to each side with polyurethane glue. It was surprising how much weight it would bear. Something similar with a better core might have possibilities. Maybe balsa as a core ? The Vampire used balsa core with hardwood
veneer skin on each side. That was the main structural members in the whole cockpit ! May be that balsa is way expensive now----

Honeycomb would be nice if you could find it surplus (no one but Big Gov can afford it new---- ) 1000$+ per 4x8 sheet !

Tim
 
Well, the entire cabin area of the Belite Chipper and Chipper SS are built of honeycomb panels, and those kits are pretty inexpensive, so Jim Weibe (owner of Belite Aircraft) must have found a reasonably affordable source. I know he sometimes sells off some "cutoffs" that might be big enough to use for at least part of the floorboards. The "special offers" go out to people on the mailing list for specials, etc. If you're really interested in either his source or those cut-off specials, you might reach out to him

I'm on his list because I've purchased a few of his Radiant instruments for my Patrol. I'm particularly fond of the Digital Altimeter (http://www.beliteaircraftstore.com/radiant-digital-altimeter-1/) that combines Altitude, Rate-of-Climb, Temperature, and Density Altitude on a single 2-1/4 inch instrument.
 
They sell sheets of end grain balsa, various honeycomb, and various foams as core materials. Balsa is good but heavier. I bought a bit of honeycomb and some foam. Both are easy to work with. The foam is cheaper. A 4X8 sheet of nomex honeycomb I think was about $200. I bought a half a sheet for the areas where I step.
 
The 50 gallons of gas over my head scares me a lot more than CF. My second greatest fear is realizing I don't have enough of the 50 gallons left.
 
By the time impact forces shatter your CF interior getting cut by it is the least of your worries. We use CF in interior aircraft monuments all the time.
 
Read a report by a Carbon Cub driver who cracked up his airplane and to this day has carbon fibers buried in him that they can’t remove that drive him crazy. Why ask for that kind of trouble.
 
Is that single incident the only cause to completely reject an entire material group? Build the plane you want, but that seems silly.
 
Well not an isolated incident, I think carbon fiber is a great material for structural work but would be reluctant to use it for interior panel work.
 
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sexy and light aren't the only requirements/drivers for choosing a material. :)

durability, repair-ability, cost, mounting, cost to make a design change, etc. all come into the mix. The Carbon Cub guys are looking for light, but also sexy, but I wonder about durability and the hazards associated with fabrication, damage and repair. Large Aircraft do a lot of things we can't build into ours, but show me a 737 that has a cost/flight hour under $2500 bucks and can land in 350 feet and then we can compare approaches to system function, design and materials.

I have some cub time flying in Wyoming and I'm sure the Carbon Cubs are great aircraft, but cracks in fuselages are a lot easier to identify in good ol' 4130 than they are with any composites. Floorboard take a lot of abuse, can a sheet of composite take it, if you core it can the core handle the damage, how do you identify it? how easy is it to fix and what does that do to the weight?

Also a big carbon plate between your upper antenna's and lower antennas (GPS, COM/NAV) can cause problems with interference? Corrosion...Carbon is the natural enemy of aluminum and other metals we routinely use to build with...Large aircraft spend a lot of energy to paint, seal, coat etc.

Carbon, Kevlar have their place in aircraft construction, but builders have to understand the pro's and con's...and if you're gonna use it, know that you will get a splinter and you may never get it out! The nice thing about experimental you can make it then way you want...if you want comp floor boards, go for it!

Andy
 
Pretty sure commercial aircraft that use composite panels for the floor see a lot more abuse than anything in GA, though they are usually covered with carpet or floor pans. The 1/2" 3-ply 9lb core stuff we usually use is different than the 1/4" 2-ply 3lb I'm using for the Bearhawk, I will need to take efforts for additional protection in the baggage and foot areas. Also pretty sure carbon cubs still use 4130 tube fuselages. Not sure how a carbon plate between antennas can cause interference. CF does block RF so you don't want to surround an antenna with it, like a wingtip VOR, but floorboards made of the stuff wouldn't be an issue, or any more of an issue than the steel cage we're fixing these antennas to. Corrosion is always something to keep in mind when designing and building airplanes...

If you're worried about splinters in an apparently inevitable crash, don't make your instrument panel out of CF.

Don't discount entire material groups because of an impression, understand there are reasons they're used everywhere by nearly everyone...
 
I hear ya Dave, worked in the industry for 27 years (manufacturing/design/maintenance and operations) and extremely familiar with carbon, etc. I just throwing out some data for those that are trying to decide if they want to go down the composite rabbit hole. It's not a simple replace the .025-.032 aluminum with a carbon sheet or even sandwich.

I ran depot level maintenance on business jets and Boeings (737/4/5/6/7). They use comp floor panels to save weight on the passenger birds and the cargo handling systems for the freighters don't actually touch the floor boards, but are locked into rails. Chubby girls in high heels are the bane of comp floor boards...in fact we had an issue with the 767 Tanker as several areas we had to design new floorboards because the aircraft wouldn't have carpet or the dime mat.

I guess the point I was trying to make was when you add up the cost, hazmat, durability, special mounting considerations...sometimes aluminum with some rhino liner on it makes more sense!

The time we beat this horse we could have made a set of floorboards! ;)
 
Sure, but as someone who has actually fabricated and installed composite sandwich panels floorboards on my Bearhawk I'm saying it is nearly a direct replacement for the aluminum panels, aside from having to raise your controls that is. If you have the opportunity I highly recommend it.
 
We have a light weight marine carpet on our floors. If a person is going to coat the aluminum with truck box liner then consider doing it on the topside so it does double duty for sound and wear. if a person is truly worried about the floor drumming then they could use a Harbour Freight metal roller to roll some stiffening into the panels similar to the car guys fabbing their floors. Could roll simple x's in that fid between the fuselage tubing. It does not have to be a sophisticated as this but it give the idea.
https://www.youtube.com/watch?v=UQ5kkEYPx-A
 
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LOL...man I've been just hammered with work, changed jobs and with a kid getting married, my Mom passed and the general silliness of the plannedemic I haven't been able to get on the forum as much as I would like. I have been building wing parts though. I still owe Mark G. some CAD drawings so I'm trying get back in the saddle. Andy
 
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