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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.
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I actually didn’t have any interference problem in my Patrol going to 6 mm Baltic BirchLast edited by spinningwrench; 03-09-2019, 12:14 AM. -
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.Last edited by Archer39J; 03-06-2019, 02:12 PM.
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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.Comment
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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.Comment
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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.
AndyComment
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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. -
The composite sandwich panels I used are great, if less flexible than the aluminum panels. Worth it for the sound absorption at least. Not hard to fasten either. Heel punch is a problem, same as in AC monuments, but easily mitigated.
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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.
AndyComment
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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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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.
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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.Comment
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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
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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
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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/r...l-altimeter-1/) that combines Altitude, Rate-of-Climb, Temperature, and Density Altitude on a single 2-1/4 inch instrument.
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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.Comment
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Carbon fiber turns into thousands of little razor blades when it shatters. I would not consider using it for a cockpit interior.Comment
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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.Comment
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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.Comment
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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.Last edited by spinningwrench; 03-20-2019, 11:45 AM.Comment
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