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From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1321090@logan.com>
Subject: Re: [FlyRotary] Re: Emailing: DoorOpenLside.jpg
Date: Sun, 13 Aug 2006 18:45:55 -0400
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Hi David,

You are right on all counts, fortunately- it is not a timber beam.  Its 
actually a engineered box beam very similar to wooden spars built for 
aircraft.  But, without quite as much attention to weight savings {:>).  I 
used Liquid Nails Subfloor adhesive after discussing my project/needs with 
their technical staff (learned a bit about wood glues/adhesives) and deck 
screws to build the beam.  It weighs around 180 lbs.

Its basically a warren truss enclosed in plywood.  It just took less work 
(more lumber, but less work), to have the building material store cut me 16" 
wide strips of plywood (4 to a sheet) and then use those as the webs rather 
than cutting out the gussets necessary for each brace/flange interface to 
build an wooden open warren or Pratt truss.  It would be interesting to see 
how light the beam could be made, but I've been working on building hangars 
and doors since around March and wanted to see the light at the end of the 
tunnel {:>).  Besides, I can't fly until the door is finished as my aircraft 
is trapped inside!!!

Appreciate your comments

Ed

----- Original Message ----- 
From: "david mccandless" <daval@iprimus.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, August 13, 2006 6:23 PM
Subject: [FlyRotary] Re: Emailing: DoorOpenLside.jpg


> Hi Ed,
> I do not need a door nor a hangar, but as the discussion progresses I am 
> becoming more interested.
> I would have thought that a Warren type truss, fabricated from, say, 3 
> inch channel for chords and 2 inch angle for webs, would have been a 
> better and lighter solution than a timber beam.
> Is that big center beam a laminated truss or a plywood fabricated beam?
> I am an old structural engineer from 40 years ago, I have a lifelong love 
> of bridges, and have never loss my interest in beams etc, so this is not 
> meant to be criticism but rather to satisfy my own curiosity.
> BR, Dave McC
>
> On 14, Aug , at 5:51 AM, Ed Anderson wrote:
>
>> I am convinced (but have not done a comparative analysis) that this 
>> arrangement does produce less outward force on the top of the door 
>> frame/hanger than a bi-fold.  The hydraulic ram ends up at a 47 deg angle 
>> to the ground and so supports  approx  70.7 % of the door weight.  If the 
>> door weighed 600 lbs finished then I estimate the door frame would 
>> support approx 200 lbs and the ram 400 lbs.  Since the "balance" point of 
>> the door is along the axis of the beam this should mean very small 
>> outward forces once the beam is raised.
>
>
> --
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