LMA Build in the UK, to SSDR spec.

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flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
216
Location
Downham Market, Norfolk, UK.
For some reason that I can't figure out the 'designer' of the LMA decided that the Leading Edge/D-Box dosen't run from the capstrips off the top and bottom of the mainspar, so been spending time looking at UK suppliers of 2024-T3 sheet 0.016" as were going to need a wider strip if alloy to achieve a better top and bottom surface for the ceconite covering. Made a 'dummy' D-Box out of a spare piece of alloy, and it just looks 'right'!!!. more pics will follow tomorrow.
 

pwood66889

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Joined
Feb 10, 2007
Messages
1,630
Location
Sopchoppy, Florida, USA
"For some reason that I can't figure out the 'designer' of the LMA decided that the Leading Edge/D-Box dosen't run from the capstrips off the top and bottom of the mainspar..."
Neither did Fred Weick, designer of my Ercoupe. Off hand I'd say that it got most the tortional stiffness from the bend at the leading edge.
 

flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
216
Location
Downham Market, Norfolk, UK.
"For some reason that I can't figure out the 'designer' of the LMA decided that the Leading Edge/D-Box dosen't run from the capstrips off the top and bottom of the mainspar..."
Neither did Fred Weick, designer of my Ercoupe. Off hand I'd say that it got most the tortional stiffness from the bend at the leading edge.
Hi Pwood, If I recall the Ercoupe wing is metal ???, where the LMA is fabric, so the fabric would 'scallop' aft of the smaller d-boxover the ribs.
 

pwood66889

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Joined
Feb 10, 2007
Messages
1,630
Location
Sopchoppy, Florida, USA
Ercoupe wings started out fabric covered. It was designed in the late 1930's, after all. Just got the second recovering job back at the hangar.
Later wings were "metalized" at the factory, but field upgrading was available. They used the same Warren truss style, with the forward spar taking most all the loads.
 

flywheel1935

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Joined
Nov 1, 2018
Messages
216
Location
Downham Market, Norfolk, UK.
Excellent, sir. Adapt and over come! Onward!!
Thanking you in advance for the pictures.
Hi pwood, Nick Onn called me earlier today, & when lockdown is over ????? he said to pop over to his airfield where he keeps his brace of Sukhois. Keystone Heights.
In the meantime, I plan to spend 2-3 hours a day at my Airstrip, to play catch up. Both wings are now at the same stage, so its time to mod endplates and
look at control cables ( Teleflex) .
 

flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
216
Location
Downham Market, Norfolk, UK.
I currently have "Build Manuals" for 3 LMA Aircraft, The Cub, The Aeronca Champ & the Taylorcraft (2 seater) Although all 3 should share the same wing ???
the lift Strut pick-up point on the Taylorcraft (The one I'm actually building) is 14" or one bay further to the wingtip than the other 2 aircraft, meaning the strut to lower airframe angle is only 20 degrees, what would be considered the optimum angle ???? 20 degrees just looks to shallow.
 

flywheel1935

Well-Known Member
Joined
Nov 1, 2018
Messages
216
Location
Downham Market, Norfolk, UK.
Had another day at the 'Playground' today & got the revised lift strut points in place.
Picking up the 2024-T3 for the D-Box on Tuesday, UK price on par with USA prices 12ft x 4ft x 0.016" @ £221.00 ($250 + -)
looking at doing an Alloy spar version on MK11 next year, in 6061-T6.

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