Draco Crash Today!

[turboplanner]

Perhaps you could post a link to the NTSB report? I cannot see how a falling leaf manoeuvre would allow an aircraft to reverse into the ground. A falling leaf is simply a sequence of consecutive incipient spins. 

 

It was about 25 years ago; look for 152 and 172 also in case I got the model wrong.

 

The engine was either knocked out in a mid-air or shook out.

 

 

[aro]

Having BOTH wings fail at the point of attachment to the fuselage without any obvious damage otherwise , shows a design weakness pretty clearly. Nev

 

I suspect it really shows how much force can be generated by an impact at the wingtip - much greater than flight loads.

 

One wingtip hits the ground, that wing folds upward and the other wing immediately falls downward. So I suspect the stiffness wasn't in the wing attachment, it was in the carry through which failed when the wing tip hit the ground.

 

It's not really important whether the wings stay attached in a crash - you need the passenger compartment to stay intact. The lack of injuries to the occupants suggest that it did a good job in that respect.

 

 

[facthunter]

 It's obviously far weaker than is should be and that section will take all the strain  and fail early if it's built like that. A wing is designed for sheer and bending loads at all places and has to be much stronger near the wing root as that's where the greatest bending load is. The wings didn't crease or bend Just snapped off clean at the wing root. Not good. Was that wing originally  designed for a strut to be used? There's no evidence of that in the production models and it's an old design.  Nev

 

 

[Blueadventures]

 It's obviously far weaker than is should be and that section will take all the strain  and fail early if it's built like that. A wing is designed for sheer and bending loads at all places and has to be much stronger near the wing root as that's where the greatest bending load is. The wings didn't crease or bend Just snapped off clean at the wing root. Not good. Was that wing originally  designed for a strut to be used? There's no evidence of that in the production models and it's an old design.  Nev

 

In metals and other materials you can get the effect of accumlated over time stress / fatigue (Bit like the straw that broke the camels back); therefore at times something can fail under less stress than design catered for.  Should that ever occur in a fortunate situation then that is good / lucky as the failure could have occured in a critical place / height etc.  This is a general comment and not directed at this topics incident.

 

 

[Downunder]

As pmc stated, it was a very heavily modified design.

 

Almost all areas were modified to some degree so basically it was " experimental" in the true sense of the word.

 

I wouldn't take any damage to this aircraft and imply it is the same with Wilga's in general or a factory design fault.

 

I belive he may have extended and modified the wing tips? This is going to put unknown forces on the wing root, especially in an impact.

 

What happened to this aircraft would probably ONLY happen to this aircraft. ......

 

 

[Thruster88]

The wilga airframe is limited to only 5200 hours total time in service. It is an AD in Australia.  

 

 

[kgwilson]

I have only ever seen Wilgas once & that was at the World Precision Flying Champs about 20 years ago in Hamilton NZ. I always thought they looked a bit like a Praying Mantis.The slow flying ability and accuracy of the pilots who flew them was astounding.

 

 

[poteroo]

belive he may have extended and modified the wing tips? This is going to put unknown forces on the wing root, especially in an impact.

 

Wondering if there had been any changes made to the surface area of aileron, or the rigging of same with these mods? It didn't look like there was any effect from what he claimed was full aileron, though it's too far distant to see what deflection there was. Also can't really see whether there was rudder input to try to lift the stbd wing.  The whole design of the thing shouts that it will be very susceptible to wind on the ground.

 

 

[facthunter]

There's a gust involved . On one part of the vid the tail goes down and he did comment on that I think. It's not what you would want though. Provided there's prop clearance a forward pitch would have helped. I'm NO fan of flaperons and I think you need to fly such aircraft  using rudder rather than aileron, in some situations. Quite a few STOL planes end up dragging one wing and doing in one U/C leg and one wing written off. I've had one occasion where I was climbing away normally  and at about 80 feet was whirled into a vertical bank and slammed back onto the ground. I applied a lot of control input (DH 82) and ended up full tail down and on the ground 3 point, with the motor still full power so just cut it and rolled to a full stop. I was hardly moving and at one stage was pretty much just going along for the ride. As our man here commented with his event. What I experienced was a sea breeze coming through and a headwind became an instant tailwind with strong turbulence at the change..  You wouldn't want to be  a student on a first or second solo.  One needs a bit of luck on these occasions. Nev

 

 

[Thruster88]

Draco is returning 

 

 

 

 

[farri]

Keep trying to find the limit and eventually you will!!!

 

Franco. 

 

 

[Downunder]

Maybe he should design from scratch....

 

Sounds like he has the funds and team to do it.....

 

Modifying to the extent he is will always run up against existing aircraft limits.

 

 

[facthunter]

Whatever rings your bell. If he's serious he should "blow" the wing. Relying on airflow when you are almost stopped is  a self defeating evercise. making you more susceptable to excursions you have no control authority over.   Nev

 

 

[Fb_Gumby]

Low speed STOL doesn't need to be "Normally" able to handle high negative G.    Strut or no strut the structure would have to achieve the design structural loads. A strut makes the wing more stiff but a normal strut doesn't work particularly well in a negative G situation. Having BOTH wings fail at the point of attachment to the fuselage without any obvious damage otherwise , shows a design weakness pretty clearly. Nev

 

Aircraft are designed to withstand specific flight loads, and except for the seats, they are not designed to withstand crash loads.  So it seems to me that attributing the damage to a design weakness in this case (a crash) misses the mark.  You cannot say there was a design weakness, because the wings were not designed to stay on in a crash.  No aircraft wing is designed to stay on in a crash. 

 

 

[Student Pilot]

Aircraft are designed to withstand specific flight loads, and except for the seats, they are not designed to withstand crash loads. 

 

Don't know about eastern block designs but anything made in the west in the last 50 years or so the seat design has to meet certain crash standards. 

 

 

[Fb_Gumby]

Don't know about eastern block designs but anything made in the west in the last 50 years or so the seat design has to meet certain crash standards. 

 

And that is why in my original post on this subject, I made and exception for the seats in an aircraft.  You are correct, the seats are designed to specific crash loads which I believe are 9G down and 9G forward.