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Flight test to failure

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Kirk Smith

Joined: 10 Jan 2006
Posts: 78
Location: SE Michigan

Posted: Mon Mar 06, 2006 9:01 am Post subject: Flight test to failure

Here's an excerpt from a letter I recieved from the original Kolb Co. Inc. several years ago on testing an Ultrastar to destruction. 

  "The Ultrastar was the immediate predecessor ot the Firestar, the two ultralights share the same wing. The only difference is that the drag strut is positioned in the firestar at a more favorable angle, making it a little stronger than the ultrastar wing in resisting drag loads. Since the wing of the firestar is at least as strong as the Ultrastar, the flight test to substantiate the G-load rating for the Ultrastar is valid for the firestar as well. The test Ultrastar was equiped with two recording  G meters for measuring the G-load rating."

<Skipping ahead to the actual destruction test>



" To obtain 5 1/2 G's required  a full power dive at approximately a 40 degree angle below the horizon. The 5-1/2 G's was of much longer duration than typical loops performed at 4-1/2 G's. Incidentally, this 90 mph dive and 5-1/2 G pullout was an exciting ride even for one accustomed to performing ultralight aerobatics.

  At this point, we felt that the ultrastar had been well proven to be as strong as anything in it's class would ever be required to be. There is just no way that any pilot would ever accidentally get into such a high speed dive situation ( to which would have be added an abrupt pull out) to get into such a high G-loading situation. But it was decided to do one more test to 95 mph. An abrupt and sustained pullout at this speed resulted in structural failure of the left wing; the drag strut failed and the wing folded back alongside the fuselage." 





Happily the pilot and plane safely parachuted to ground.

Kolb company rebuilt the plane and strengthened the wing even more and the improvements were passed on to ultrastars, firestars and twinstars.

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ul15rhb(at)juno.com
Guest

Posted: Mon Mar 06, 2006 12:50 pm Post subject: Flight test to failure

-- "Kirk Smith" <snuffy(at)usol.com> wrote:




"Happily the pilot and plane safely parachuted to ground.

Kolb company rebuilt the plane and strengthened the wing even more and the improvements were passed on to ultrastars, firestars and twinstars."



That pilot happened to be Dennis Souder President of Kolb Aircraft at the time.



Ralph

Original Firestar

19 years flying it



Here's an excerpt from a letter I recieved from the original Kolb Co. Inc. several years ago on testing an Ultrastar to destruction. 

  "The Ultrastar was the immediate predecessor ot the Firestar, the two ultralights share the same wing. The only difference is that the drag strut is positioned in the firestar at a more favorable angle, making it a little stronger than the ultrastar wing in resisting drag loads. Since the wing of the firestar is at least as strong as the Ultrastar, the flight test to substantiate the G-load rating for the Ultrastar is valid for the firestar as well. The test Ultrastar was equiped with two recording  G meters for measuring the G-load rating."

" To obtain 5 1/2 G's required  a full power dive at approximately a 40 degree angle below the horizon. The 5-1/2 G's was of much longer duration than typical loops performed at 4-1/2 G's. Incidentally, this 90 mph dive and 5-1/2 G pullout was an exciting ride even for one accustomed to performing ultralight aerobatics.

  At this point, we felt that the ultrastar had been well proven to be as strong as anything in it's class would ever be required to be. There is just no way that any pilot would ever accidentally get into such a high speed dive situation ( to which would have be added an abrupt pull out) to get into such a high G-loading situation. But it was decided to do one more test to 95 mph. An abrupt and sustained pullout at this speed resulted in structural failure of the left wing; the drag strut failed and the wing folded back alongside the fuselage." 





Happily the pilot and plane safely parachuted to ground.

Kolb company rebuilt the plane and strengthened the wing even more and the improvements were passed on to ultrastars, firestars and twinstars.





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=19920#19920





 

 

 

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