Wood Inserts

highlandhovercraft
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Wood Inserts

Post by highlandhovercraft » February 24th, 2012, 3:11 am

Just looking on an old set of drawings I have for an Explorer (1997). I had these given to me a year or two ago, but have no written instructions. My new set of plans are enroute from you and should be here any day, but just trying to suss out what is involved in the building and what materials I need to order. (I'm in the UK)

In the drawings there are several pieces of wood inserted into the panels. Floor panel H6 which is 1" thick has 3/4" X 1 1/2" clear fir set in across the rear and around the fan bay. (drawing 2)

How is this wood set in as it is either 1/4" too thin or half inch too thick compared to the panel

The same goes for panel H7 where there is a 3/4" X 3 1/2" X 60" clear fir glassed into a 1/2" thick panel. (Drawing 2) As there is a left & right and the wood is thicker than the panel, which side is the wood protuding 1/4"?

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bphillip2
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Re: Wood Inserts

Post by bphillip2 » February 24th, 2012, 8:09 am

The wood thickness is based on stock lumber available in the states. A 1x2 is .75x1.5, after milling and sanding. I would suggest replacing the wood entirely with alternative structure. Through the fan box along the outboard edges I double the thickness with scrap foam, adding stiffness to this area. The forward and rear edges of the fan box can be high density foam(25 lb urethane) or extra layers of glass. That corner gets hit as the craft lands, tail first(use brake to land move level).

You can create super hard points for through bolting engine mounts of threading screws by adding 1/8" milled fiber to microballon mix(included in sevtec lam kits).

If you use wood you need to seal it with epoxy first(3-5 coats), then sand to allow adhesion of standard lam resin.

This applies to all models.

Bryan
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highlandhovercraft
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Re: Wood Inserts

Post by highlandhovercraft » February 24th, 2012, 1:05 pm

HI Bryan,

So basically no wood is used in the explorer construction. Wood is replaced by high density foam & extra GRP reinforcement.

You mentioned the super hard point mix is a mix of micro balloons and milled fibre.

Is it either of these products?

http://www.cfsnet.co.uk/acatalog/CFS_Ca ... s_400.html

http://www.cfsnet.co.uk/acatalog/CFS_Ca ... s_399.html

Obviously shipping fillers etc from the USA to the UK would be expensive

On my surveyor I used micro balloons but have found that some of the self tapping screws became loose after they had been removed a couple of times. I was thinking about mixing in some 1/4 inch strands with the micro balloon mix on this build in a bid to add strength.

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bphillip2
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Re: Wood Inserts

Post by bphillip2 » February 24th, 2012, 6:49 pm

Use the milled fiber, chopped is no fun at all. The product description fails to mention fiber length, which important.

highlandhovercraft
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Re: Wood Inserts

Post by highlandhovercraft » February 25th, 2012, 12:19 am

Thanks Bryan

scottie
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Re: Wood Inserts

Post by scottie » February 25th, 2012, 9:53 am

Hi All
On my build I used wood to make those inserts for H6 and H7 at the base of the fan box. But after reading that other Explorers had problems
with that area I decided to add Aluminum to give the wood more protection from ruff service.
just a thought
Scottie

highlandhovercraft
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Re: Wood Inserts

Post by highlandhovercraft » February 26th, 2012, 12:54 pm

Talking of H6, what are the two inner rows of hardpoints for? I know the outer ones are for inner skirt attachment. The front arc is the partition skirt. Are the other two sets for extra runners on the floor? or is there another purpose for them?

When you say aluminium, was this ally sheet made into guards and screwed into the wood after hull was finished.

scottie
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Re: Wood Inserts

Post by scottie » February 26th, 2012, 1:30 pm

Hi
I used Alum 1 1/2 x 1 1/2 angle stock on the front and back and 3/4 stock on the sides. Welded it together and screwed it to the inside of the wooden supports. Also I didn't make the standard hard points but inlaid strips of pressure treated pine then covered the joints with micro balloon fill and covered that with fiberglass cloth. That made the attaching the skirt a simpler process.

highlandhovercraft
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Re: Wood Inserts

Post by highlandhovercraft » February 26th, 2012, 3:17 pm

highlandhovercraft wrote:Talking of H6, what are the two inner rows of hardpoints for? I know the outer ones are for inner skirt attachment. The front arc is the partition skirt. Are the other two sets for extra runners on the floor? or is there another purpose for them?
I just saw the answer to this on the plans. I really should look harder :oops: :D

highlandhovercraft
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Re: Wood Inserts

Post by highlandhovercraft » February 26th, 2012, 3:24 pm

scottie wrote:Hi
I used Alum 1 1/2 x 1 1/2 angle stock on the front and back and 3/4 stock on the sides. Welded it together and screwed it to the inside of the wooden supports. Also I didn't make the standard hard points but inlaid strips of pressure treated pine then covered the joints with micro balloon fill and covered that with fiberglass cloth. That made the attaching the skirt a simpler process.
I must admit I'm not a fan of micro balloons for hard points. This time I am going to try & get milled fibres as Bryan uses now. I found micro balloons wouldn't nold self tapping screws very well after they had been undone a couple of times. A simple way would be to use a hard wood brush handle cut into 1" strips, as long as the screw holes were sealed with silicon or similar when the skirt is fitted

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