What happened at PRS to make the Viper L-29's unsafe?

[supercub]

I was wondering what happened during PRS that alerted the officials that the Viper powered L-29's were unsafe? What changed this year with them over previous years?
Brian

[Race5]

Re: What happened at PRS to make the Viper L-29's unsafe?

Let's just say we came REALLY close to having another inflight break up to discuss.

[AirDOGGe]

Re: What happened at PRS to make the Viper L-29's unsafe?

I guess it's like taking the family Chevy out on the race track for some hard racing at high speeds. it just isn't built to take that kind of pounding, and so something, somewhere is gonna break.

[Race5]

Re: What happened at PRS to make the Viper L-29's unsafe?

I guess it's like taking the family Chevy out on the race track for some hard racing at high speeds. it just isn't built to take that kind of pounding, and so something, somewhere is gonna break.

Actually it's more like taking a ford Pinto, adding a 1000hp engine using 2x4s for the mount and taking it to Daytona or Talladega. Sure it will haul a$#. Until it comes part or crashes.

[supercub]

Re: What happened at PRS to make the Viper L-29's unsafe?

Does this relate to the problem that I believe it was Race 21 had with a fire and tail problems?
Brian

[MMPerk]

Re: What happened at PRS to make the Viper L-29's unsafe?

There wasn't actually a fire. It just kinda looked like there was.

[Race5]

Re: What happened at PRS to make the Viper L-29's unsafe?

There wasn't actually a fire. It just kinda looked like there was.

Just a lot of melted aluminum....

[MMPerk]

Re: What happened at PRS to make the Viper L-29's unsafe?

Yep...I know when I first saw it, fire was the first thing that I thought of. It was huge setback for the team, but they overcame it, made things right, and now they have to sit this one out. I enjoy the jets, but then I enjoy all aspects the event. And besides, how many of you really think that Heather 'Lucky' Penney would get in the cockpit of an aircraft that she felt was less than safe?

Have a great evening, and I hope to see you at the races!!

LP

[bflynt]

Re: What happened at PRS to make the Viper L-29's unsafe?

What is with the "I know but I'm not going to tell you" replies in this post? The person (supercub) asked a simple question and all he gets is several criptic answers. Is it really that sensitive of information?

1st Issue:
The accident report for Raju Grace is public, find it here:
http://www.ntsb.gov/aviationquery/br...18X92834&key=1

My interpretation:
The motor was/is too powerfull for the mounts they used and they failed. This may be fixable with a re-design of the mounting but I'm guessing all the other viper powered L-29's had the same install.

2nd Issue:
The L-29 jets are exceeding the flight envelope they were designed for. The larger motor pushes them faster and combined with the higher air density of flying low they are experincing compressiblity effects. This results in a nose down pitching moment which if sudden or unexpected could result in someone flying into the ground. Most people call the phenomena "Mach Tuck"

Both issues could be worked around, but obviously it would take some time and ultimately $$$ to fix.

[Race5]

Re: What happened at PRS to make the Viper L-29's unsafe?

What is with the "I know but I'm not going to tell you" replies in this post? The person (supercub) asked a simple question and all he gets is several criptic answers. Is it really that sensitive of information?

1st Issue:
The accident report for Raju Grace is public, find it here:
http://www.ntsb.gov/aviationquery/br...18X92834&key=1

My interpretation:
The motor was/is too powerfull for the mounts they used and they failed. This may be fixable with a re-design of the mounting but I'm guessing all the other viper powered L-29's had the same install.

2nd Issue:
The L-29 jets are exceeding the flight envelope they were designed for. The larger motor pushes them faster and combined with the higher air density of flying low they are experincing compressiblity effects. This results in a nose down pitching moment which if sudden or unexpected could result in someone flying into the ground. Most people call the phenomena "Mach Tuck"

Both issues could be worked around, but obviously it would take some time and ultimately $$$ to fix.

The broken motor mount was part of it, but not all of it. As far as fixing the mach tuck issue, sure it could be delayed to a higher speed. Then you have aircraft that are too fast for the course at 550 doing 575. It's a no win situation.

[Randy Haskin]

Re: What happened at PRS to make the Viper L-29's unsafe?

Lots of good discussion about this over at the CJAA Forum. The interesting part to me is that all of the other Viper L-29s were inspected, and none of them had the issues that Raju Grace did.

Yet...one person poops, and everyone gets to wear diapers.

For those who are interested, some of the other posts on the Classic Jets forum were rather entertaining. The part about "jets are getting faster and more exciting than the Unlimiteds", and that's the REAL sinister reason that Mike Houghton is trying to restrict what jets can fly in the field, is one of the best!

[Arctic Cat]

Re: What happened at PRS to make the Viper L-29's unsafe?

Jets suck!

Even when they are running 500+, they are boring. Half the drama of a 480+ lap with an unlimited, is the knowledge that at any second the internals of the engine can become externals. The sound of an engine and prop screaming against the air, will never be replaced by a hopped up hair dryer.

With that said though, one of the coolest laps ever was Jimmy in the mig with the burner lit for that one lap.