Eagler's Nest
Airframes => Double Seaters => DE => Topic started by: KWK on August 29, 2026, 05:09:54 PM
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There have been numerous parasol designs over the years, and the Double Eagle is one of the more recent examples. The DE is different in having no bracing between the wing lift struts. Most designs have either wire X bracing or an extra tube to form an N brace. Some Heaths were built with V struts, but these also have a guy wire coming back from the firewall. In looking at my plans, it seems to me the front cabane isn't fully triangulated to resist wing loads in the yaw direction, say a kick to the rudder. What am I missing?
Edit: I think I see what I was missing. The aft cabane is the point about which the wing would try to rotate in yaw, for it's fully triangulated into the main fuselage. As such, the front struts would resist lateral motion of the front spar. The front cabane instead holds the firewall upright and carries part of the vertical lift on the front spar. It doesn't need to support the front spar in the lateral direction.
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There is some drag/anti drag structure in the wing, but personally I think all the non cabin Eagles could benefit from sweep wires.
A set from as far forward as possible to as far out on the wing as possible, and another set connecting with those continuing back to the tail post.
Flexing eventually causes fatigue cracks and broken tubing. This was brought up once before when cracks were found in the front cabanes, but the airframe had a 2 stroke motor and "vibrations" were blamed. To check for flexing, the tail is braced and the wingtips are moved fore and aft.
Flexing can be thought of as low frequency vibration I suppose.
Just an opinion mind you.
https://aviation.stackexchange.com/questions/56099/what-is-the-function-of-a-sweep-cable (https://aviation.stackexchange.com/questions/56099/what-is-the-function-of-a-sweep-cable)
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Good point about the racking strength of that light wing.
The thought to add wires fore and aft had occurred to me as well. It seems that would better anchor the wings in yaw than the usual X or N bracing between the struts.
Please tell me more about those cracks observed in the front cabanes, such as which joint(s) and which model Eagle.
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There is a first time for everything I guess... I have so far struck out on finding that post...
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Thanks for looking. I didn't have any luck finding it either, but it does sound familiar. Nor can I find it in my notes on the DE. I did see mention of it on HomebuiltAirplanes but with no details.