Quote:
Originally Posted by hank jarrett
There was a discussion started on the Pilots Reports thread that started to get pretty technical and we are going to move over here to continue it. ...
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Hank:
OK, I finally caught up. I was confusing this with another thread, but now I've read past the BRS discussion.
Machinbird posted some links. I read the article/transcript on bd5, but it will take me a while longer to finish wading through the advisory circular/testing handbook. In the meantime, I will hold off on my earlier question about how to develop a test program and where to find the right "Boffins."
I've probably read 5-6 first hand accounts by test pilots, but never from the point of view of needing their services or needing to test an aircraft. There are a few more on my bookshelf, so when I read those I'll be looking at them from a new angle.
So, I'd like to ask about using WW I replicas for aerobatics instead.
I read many firsthand pilot accounts. Of all the WW I first hand accounts (and even a number from WW II), aircraft were rendered unsuitable for frontline service very quickly. I think I recall, by 1943, the Brits would pull an aircraft once it hit 100 hours operational flying.
During WW I (based on my anecdotal reading), if a patrol of 6 launched, 1 was almost guaranteed to turn back for various reasons. Within the AEF 3rd Pursuit Group (213th in Summer 1918) in France, their aircraft were in such bad shape, they always scheduled two standby pilots/planes because most of the time two of the designated planes had to abandon the operation before take-off. Another 2-3 would develop issues in the first 15 minutes of the patrol.
A high percentage of these issues were mechanical directly related to unreliable engines. Many more were 'buses' cobbled together from pranged ships, or they suffered battle damage resulting in a patchwork of repairs.
Still, many of the issues were pilot complaints about one "wing heavy", lack of response to control input, poor rigging, and other airframe & control surface matters not related to the early engines.
So, for aircraft using original construction methods that are all wood (e.g. Nick's Snipe) or aircraft with wooden spars (e.g. Jeff Brooks' DVII projects and the various DR I projects), would the repeated stresses eventually lead to weakening of the spars or other critical structural parts?
How would an owner/builder determine an acceptable lifetime for use in aerobatics?
Or is it just a matter over never over-stressing and routine inspections?
Can inspections reveal the most likely issues and/or incremental damage?
...and then what about metal fatigue, particularly on welds?
I read about replicas involved in aerobatic displays, so I know it can be done.
I've also read accounts (in Rickenbacker's book for example) where a virtually new aircraft's wing could fail and fold back in an otherwise normal power dive (Spad VII I think).
...sounds dangerous...not my choice for a faithful to original replica...
I should add: I don't know any of the builders and have no idea about their intentions or goals. I am just following their projects with keen interest and their aircraft seem to be good examples of the construction methods.
I do know their projects really sparked my interest, and I think it would an incredible natural high to do loops, barrel rolls, and spins in a Sopwith Pup or Triplane built by myself.
That is a rather muddled question (or open ended comment?), but I look forward to your response.
Thanks,
Brian