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Richard, do you have drawings for that canard? I'd like to put them up on the files section of the Q list.
Actually there was another option on the LS1 for the spar and build that was not a QAC design. We did do load and twist test with it back when we were trying to bring these planes back to a production kit and found it to be a bit stronger than the tube spar QAC had. The LS1 I'm talking about is the Weishaar-Doyle LS1 canard.
On Mon, Feb 15, 2021, 3:15 PM Jay Scheevel <jay@...
Not to put words in Charlie’s mouth, but I think I heard him say (when he was showing me a structural simulation of the LS1 canard on his computer) that he felt the weak link in the chain was the skin/foam sandwich forward of the tube spar and inboard but not too far from the fuselage. That seems to be the place where the delamination has happened on numerous aircraft, even where the canard did not break.
The official QAC line was that the tubular spar was required because of the thin profile of the LS1 would not allow enough flexural strength if it that shape of airfoil was laid up conventionally. I think a properly engineered I-beam spar (or two) would probably fill the bill, but no one has tested that idea to my knowledge. QAC probably looked a the tube spar as a way of ensuring that customers did not drift towards hand building Q200’s without buying kit components from them. I would not write that motivation off entirely.
So many more options exist now. I think anything requiring an autoclave should be ruled out for the general public, as it is not a tool that is available to most. The best bet would be to find an enthusiastic, enterprising, young graduate student, who is good with composites analysis and solid works, and ask them to do some modeling of proven hand laid up carbon fiber spar configurations subjected to end loading (like the standard Q and Dfly configuration), combined with line loading that would simulate the fuselage shell wall loads. If it was proven by computer modeling, then you would only have to build one canard design for testing to failure.
My 2 cents.
I couldn't recall if it was the Wing or Canard..thank you for the clarification, Jay. Here is what Charlie and I both are
concerned about.. the Canard, especially in the MKI config, takes a beating in this design. Neither D-fly or Q2 have
had the Canard tested (that we know of) and I cannot be certain of the load limits in my own aircraft.
So the airplane geek I was trained to be finds this situation unacceptable. Too many years in the factories worrying
about "what if's!" I am concerned we have had structural fails..thank goodness not to the point of
augering in from 10,000 feet. There are indications of upper skin delam from the canard core..and crush of the core
leading to compression fails right where we expect these conditions to happen. The bond between the core and upper
glass layup degrades over time...so the margin in safety to peak load will be reduced.
So I have the question here.. I can build a fixture that can easily use my 1/2 ton Dodge truck to provide a stabilized test
fixture (the data plate on the truck indicates the mass we have to work with, also not a problem having certificated scales
weigh the vehicle). How much in todays materials would a canard cost to build? No need to add finishes because these
are not going flying..these are going to test to fail (if possible). I prefer testing the Dragonfly Canard for the reasons
explained before. The M.E. within wants to test what is more likely of a successful build by the homebuilder in her/his
We MIGHT be able to effectively tool for Q2 Spars and test those also. We would need to know the exact ply schedule,
finish, and resin used at QAC. What finish dry carbon fiber also. What tapes used? A far superior part would be possible
with pre-preg ribbon and the correct mandrel...but then the problem of autoclave and accurate cure arises. It might be
possible to correctly pre-preg fab the tapered tube Spars using internal inflated balloon methods and then cure the entire
tool with the layup and mandrels in a controlled oven.
I think that Waddelow load tested his LS1 spar-less canard, but I do not know the limits. Maybe Bruce Crain has that information.
The test of the main wing at LVK was in 2008 and tested to a max of +4.4 G’s (2000 lb. of sandbags) with deflection of 10.5 inches on each wingtip, that returned to its original shape.
I agree with what Vern is saying. I only thought I would look up the data so I can correct what I said earlier about 18” of deflection. Was really 10.5”
The only test was in the news letters. Q Canard was tested in the past with static to 1200 lbs (positive).
Sand bags from the local Big Box home improvement center. On release, the tested surface resumed
original design config(Q2, MKI Anhedral if my memory is correct)
The point is, from all builders/owners in the newsletters or blogs, of yet no test of either Dragonfly or Rutan Q surfaces
(Wing or Canard) have been performed to failure..so there is no definite known max load other than Finite Element work.
Here is one project I had a bit of a hand in
She went 150% in this photo (and did not break). I've flown over the Atlantic in a 787-9 but the wings were
not at this point of flex. I am pretty sure if they were my wife would have been a bit more than worried since
she was with me on that flight from Stockholm to Ft Lauderdale.
When fail is reached it is upper surface compression, most often beginning at shear surface bondline (contact) from
the spar/ribs to IML of the upper surface layup. Failure happens almost instantly but the strain gauges tell the tale
In our case the question arises of what is the bond of the glass layup to the solid core foam doing? The Dragonfly
having a different spar method than the Rutan carbon tube, so that is an important factor also. Delam of the skins
from the foam is what we aught be expecting. The flex of the resin/glass compared to the foams involved.
Big question, and now BOTH foam and resin glass are different than in the 80's. I have extra orange Q2 foam to
build the test surfaces but then again.. we can't obtain that same material now. The goal is to use what we can get
and perhaps "back test" to the older material so the "as built" materials properties are known as well.
One of my "wish list" projects is to get the time and materials together to build a set of test surfaces to go to failure
in both positive and negative G. I have not heard of any flutter issues with either structural design.
Vne may need be exceeded to discover that (sarcasm on high!)
Vern in frozen Oklahoma (Feb 12)
Hi Mike and Ryan,
I plugged 800 pounds GW into the Q200 aerodynamic model that I created several years ago (modeling the plans-built Q200). In this model, I get 67 mph CAS as the Vmin**, in ground effect. When I increase the GW to 1400 pounds, I get a Vmin of 88 mph in ground effect. So that is probably as close an answer as you are going to get to your question about flying at 1400 pounds.
I usually fly between 1000 and 1100 pounds GW. For those weights, the model produces a Vmin of 75 and 78 mph respectively.
I have also built a model that is customized to match my personal aircraft performance (Tri-Q2, with some minor aero mods). I get a Vmin of 70 mph at 1000 GW, and 74 mph at 1100 pounds. This is spot on with what I have measured in flight. At 1400 pounds, my plane would theoretically have a Vmin of 84 mph (I won’t be flight testing this!)
**I say Vmin because with a tandem wing configuration never really stalls, it just reaches a configuration where airspeed cannot get any lower and then the decent rate makes up for any energy deficit required to hold that airspeed…..but that is another story, for another time.
From: main@Q-List.groups.io <main@Q-List.groups.io> On Behalf Of Mike Dwyer
Sent: Friday, February 12, 2021 5:50 AM
Subject: Re: [Q-List] Wing load testing and max weight
If the stall speed is 67mph at 800 lbs, what would it be at 1400 lbs?
The tail dragger LS1 canard is sized for the landing impact, not the in flight load.
The factory Q200 had a 1100 lb gross weight limit. Obviously they didn't think 1400 is safe.
Two questions(ok multi part, but two subjects): How many people have done a load test on their wing or canard? If so did you just use the cement bag method and how high did you test to.
Anyone have a MTOW of 1400lbs or greater and is so what are you using?