This wingless aircraft is an ultralight I'm designing to build with 2" blue styrofoam and 1 1/2" PVC pipe for wing spars. Power will be a 22hp Briggs 4-stroke gas engine. meeceblog.wordpress.com
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3) Each of the wing panels on my Minimax weighed about 30 lbs ready to cover. 75 lbs for just the spars is crazy.Multiply that 500 pound gross weight by 6, which will give you a conservative figure for flying through a strong and unexpected gust or turbulence.
Then decide if seven pieces of cheap plastic PVC will support 6 times 500 pounds, or 3,000 pounds (that's a small car) with your life at stake.
1) I am sorry to burst any bubble here, but PVC is not a strong enough material.
2) If you are honestly trying to save money, don't forget to add the cost of the hospital and the mortuary in with the cost of your PVC wings. The total cost of those three things (trust me, they all go together) will be higher than the cost of aluminum.
Not defending the OP, but seriously, who would use PVC for a spar?I'm not too worried about the OP. If he gets this up to flight speed, the wings will snap off at an altitude of 0 feet. The danger is that he make improvements that give a 1.3g ultimate failure strength.
Thanks Victor, yours was the most informative reply I got. Not a high bar, though.
Your text sounded like you know how to stress test an airplane. I have seen 3X gross weight used for strength testing wings. Not 6X! It's not an acrobatic design.
Look at my photo at top of thread. It is a bi-plane with 1:1 ratio very low aspect sail wings. It is a cigar box frame made from 7 pvc 1 1/2" diameter spars that connect 4 styrofoam ribs.
These 7 spars will cost under $100 and weigh 35 total lbs. The 4 ribs cost about $300 and weigh 24 lbs. $400 is most of the 60-pound fuselage/wing cost. Cheap is right! Cheap is good. Otherwise poor people are never gonna fly.
The wing "box" is 15' square. How should I stress test it? How many sandbags, where, and how heavy? Where to put the supporting saw horses.?
What must be understood is that it does NOT have any skinny long cantileverd "wings" to bend and break. Look at the picture closely and understand it better before posting a reply. Keep this board informative and a supportive use of our time and resources.
It is a biplane with sails stretched across the top and bottom of a an external box frame. We're talkin ULTRa lite and ultra Affordable!!
The spars are 1 1/2" SDR-26 PVC pipe. <5 lbs apiece! 35 total lbs for spars. SDR-26 is thinner walled and about half the weight of schedule 40 pipe which is a thick-walled version for 330 psi pressure whereas SDR-26 pipe is only for 120 psi or pressureless drainage use . But it is just as stiff as thick-walled stuff. ;=] This SkyWing design yields a sixty pound bare airframe for four hundred dollars. It is modeled after a sled kite, simple and lite and flys Hi.
<<<<Multiply that 500 pound gross weight by 6, which will give you a conservative figure for flying through a strong and unexpected gust or turbulence.
Then decide if seven pieces of cheap plastic PVC will support 6 times 500 pounds, or 3,000 pounds (that's a small car) with your life at stake.>>>