Starduster Too, first flight, busted prop

Ian Stirling wrote:
Al wrote:
Well, a friend finally got his starduster too in the air. He finished it
this last winter, and has been preparing for his first flight, The flight
went well, apparently normal until shutdown. There was about 6 " of prop
missing from each end, and what was left was shattered back another 6-8".
His landing was in full stall attitude and no pieces were found on the
runway, no one heard anything, so we've pretty much ruled out a ground
strike. The videos show a perfectly normal flight although in one of the low
passes, one of the observers heard a whistling sound. I've got pictures
heading this way, and should have them posted by tomorrow. The pilot was as
surprized as the rest of us by the lack of vibration, and evidently what was
left of the prop continued to produce thrust.

I can only suppose this to be torsional vibration?
At some RPM, the propeller is twisted so hard in such a way to make the
ends of the prop wiggle off.
This sounds modereately unlikely - I would expect much more of the blade
to break off.


While that is certainly a possibility, there is something else that can
be checked
quickly and easily...

Question to OP...

In three point attitude, how much prop clearance IS/WAS there?
and
How deep was the grass?

Folk, you would not believe what grass can do to a wood prop unless
you see it for yourself.

Just a thought.

Richard

Now, if this already stated to be a paved runway, well, I'm on via
Google Groups
at the moment. Haven't figured out how the threads work yet.
Rx

Pavement, KRBG, and about 10" I think.

Al


"cavelamb" wrote in message
oups.com...

Ian Stirling wrote:
Al wrote:
Well, a friend finally got his starduster too in the air. He
finished it
this last winter, and has been preparing for his first flight, The
flight
went well, apparently normal until shutdown. There was about 6 " of
prop
missing from each end, and what was left was shattered back another
6-8".
His landing was in full stall attitude and no pieces were found on the
runway, no one heard anything, so we've pretty much ruled out a ground
strike. The videos show a perfectly normal flight although in one of
the low
passes, one of the observers heard a whistling sound. I've got pictures
heading this way, and should have them posted by tomorrow. The pilot
was as
surprized as the rest of us by the lack of vibration, and evidently
what was
left of the prop continued to produce thrust.

I can only suppose this to be torsional vibration?
At some RPM, the propeller is twisted so hard in such a way to make the
ends of the prop wiggle off.
This sounds modereately unlikely - I would expect much more of the blade
to break off.


While that is certainly a possibility, there is something else that can
be checked
quickly and easily...

Question to OP...

In three point attitude, how much prop clearance IS/WAS there?
and
How deep was the grass?

Folk, you would not believe what grass can do to a wood prop unless
you see it for yourself.

Just a thought.

Richard

Now, if this already stated to be a paved runway, well, I'm on via
Google Groups
at the moment. Haven't figured out how the threads work yet.
Rx

Al wrote:

Pavement, KRBG, and about 10" I think.

Al


Ok, another WAG?

Stardusters sometimes have rather long looking noses.

If that was 10" in level attitude - obviously not a prob.
If that's 10" clearance in 3 point? Maybe?


LAST WAG?

You found an old prop on the resturant wall?

"cavelamb" wrote in message
nk.net...
Al wrote:

Pavement, KRBG, and about 10" I think.

Al


Ok, another WAG?

Stardusters sometimes have rather long looking noses.

If that was 10" in level attitude - obviously not a prob.
If that's 10" clearance in 3 point? Maybe?


It was a good 10" in a level attitude. Far enough to strike the prop would
be scary indeed.



LAST WAG?

You found an old prop on the resturant wall?


He, He, It WILL end up on a wall somewhere. Perhaps with a clock. The
strange part to me is that he didn't notice a thing until shutdown.

I finally got some pictures up, (alt.binaries.pictures.aviation). I tried
earlier, but hit some kind of size limitation.

Al

Al wrote:
"cavelamb" wrote in message
nk.net...

Al wrote:


Pavement, KRBG, and about 10" I think.

Al



Ok, another WAG?

Stardusters sometimes have rather long looking noses.

If that was 10" in level attitude - obviously not a prob.
If that's 10" clearance in 3 point? Maybe?



It was a good 10" in a level attitude. Far enough to strike the prop would
be scary indeed.



LAST WAG?

You found an old prop on the resturant wall?



He, He, It WILL end up on a wall somewhere. Perhaps with a clock. The
strange part to me is that he didn't notice a thing until shutdown.

I finally got some pictures up, (alt.binaries.pictures.aviation). I tried
earlier, but hit some kind of size limitation.

Al




Will go take a (morbidly curious) look.

Most likely scenerio is that this prop is (well, WAS) too long for this engine.
At operating speeds, the tip sheething let go (oh, say at about 4000 to 5000
G's?), and the prop "re-balanced" itself (rather quickly) sheding the dammaged wood.

Those OLD props (say from an OX-5?) turned something like 1200 to 1500 RPM max.

What do you think, Al?

RIchard

"cavelamb" wrote in message
ink.net...
Al wrote:
"cavelamb" wrote in message
nk.net...

Al wrote:


Pavement, KRBG, and about 10" I think.

Al



Ok, another WAG?

Stardusters sometimes have rather long looking noses.

If that was 10" in level attitude - obviously not a prob.
If that's 10" clearance in 3 point? Maybe?



It was a good 10" in a level attitude. Far enough to strike the prop
would be scary indeed.



LAST WAG?

You found an old prop on the resturant wall?



He, He, It WILL end up on a wall somewhere. Perhaps with a clock. The
strange part to me is that he didn't notice a thing until shutdown.

I finally got some pictures up, (alt.binaries.pictures.aviation). I tried
earlier, but hit some kind of size limitation.

Al




Will go take a (morbidly curious) look.

Most likely scenerio is that this prop is (well, WAS) too long for this
engine.
At operating speeds, the tip sheething let go (oh, say at about 4000 to
5000
G's?), and the prop "re-balanced" itself (rather quickly) sheding the
dammaged wood.

Those OLD props (say from an OX-5?) turned something like 1200 to 1500 RPM
max.

What do you think, Al?

RIchard

It has been suggested that what he really needed was a shorter prop, and now
he has one.

At operating speeds, the tip sheething let go

This is the only scenario that fits all of the observations. I don't
understand it, exactly, but there you have it. The radial Continental only
turns 2500 or so doesn't it ? And wooden props are used on old radials all
the time aren't they? So what went wrong?

If we, for the moment, ignore witness reports, The other most likely
scenario was voiced by Capt Thorpe, "That prop had to hit SOMETHING." My
reply follows:

That prop had to hit SOMETHING.


You know, Capt., I couldn't agree more. The NTSB guy inside of me concludes
that "The prop came into contact with a stationary surface, long enough to
strike both blades". But I sure can't back it up with a single observation
and the witnesses don't support it. We did a "FOD walk down" on the runway,
and saw no splinters or strike marks. The taxi way signs apparently have no
damage, again, no splinters. The pilot didn't observe anything. He was as
shocked as we were upon shutdown. Of course it was his first flight in a
plane he built. He may be excused for not being the perfect observer. He is,
however, an ex marine, very quick wit, even somewhat humble; if he saw
something he would tell us. There were witnesses(Pilots) out on the side of
the runway during departure, and they all report no unusual noises or
events. Even the landing was reported as normal.
There has been a theory advanced that the prop tips(metal), departed in
flight causing the damage. I think the length of the cracks and splinters on
the remaining prop blades argues against this. Even a lightweight taxi sign
shouldn't cause damage like this.
I haven't given up. I think the odds of that kind of symmetrical and
extensive damage occurring in flight are slim. I will feel better when I
find a piece of prop, somewhere on the airport.

Al



-----Original Message-----
From: Capt. Geoffry Thorpe ]
Sent: Wednesday, May 31, 2006 7:09 PM
To: Al Gerharter
Subject: Starduster Too, first flight, busted prop

A buddy suggested that he might have hit a taxiway marker - I assume he has
to S turn to taxi - could he have swung a little wide?

That prop had to hit SOMETHING.


Geoffrey Thorpe
The Sea Hawk At WowWay D0t Com

Al wrote:

"cavelamb" wrote in message
ink.net...

Al wrote:

"cavelamb" wrote in message
hlink.net...


Al wrote:



Pavement, KRBG, and about 10" I think.

Al



Ok, another WAG?

Stardusters sometimes have rather long looking noses.

If that was 10" in level attitude - obviously not a prob.
If that's 10" clearance in 3 point? Maybe?



It was a good 10" in a level attitude. Far enough to strike the prop
would be scary indeed.




LAST WAG?

You found an old prop on the resturant wall?



He, He, It WILL end up on a wall somewhere. Perhaps with a clock. The
strange part to me is that he didn't notice a thing until shutdown.

I finally got some pictures up, (alt.binaries.pictures.aviation). I tried
earlier, but hit some kind of size limitation.

Al




Will go take a (morbidly curious) look.

Most likely scenerio is that this prop is (well, WAS) too long for this
engine.
At operating speeds, the tip sheething let go (oh, say at about 4000 to
5000
G's?), and the prop "re-balanced" itself (rather quickly) sheding the
dammaged wood.

Those OLD props (say from an OX-5?) turned something like 1200 to 1500 RPM
max.

What do you think, Al?

RIchard


It has been suggested that what he really needed was a shorter prop, and now
he has one.


At operating speeds, the tip sheething let go


This is the only scenario that fits all of the observations. I don't
understand it, exactly, but there you have it. The radial Continental only
turns 2500 or so doesn't it ? And wooden props are used on old radials all
the time aren't they? So what went wrong?

If we, for the moment, ignore witness reports, The other most likely
scenario was voiced by Capt Thorpe, "That prop had to hit SOMETHING." My
reply follows:


That prop had to hit SOMETHING.



You know, Capt., I couldn't agree more. The NTSB guy inside of me concludes
that "The prop came into contact with a stationary surface, long enough to
strike both blades". But I sure can't back it up with a single observation
and the witnesses don't support it. We did a "FOD walk down" on the runway,
and saw no splinters or strike marks. The taxi way signs apparently have no
damage, again, no splinters. The pilot didn't observe anything. He was as
shocked as we were upon shutdown. Of course it was his first flight in a
plane he built. He may be excused for not being the perfect observer. He is,
however, an ex marine, very quick wit, even somewhat humble; if he saw
something he would tell us. There were witnesses(Pilots) out on the side of
the runway during departure, and they all report no unusual noises or
events. Even the landing was reported as normal.
There has been a theory advanced that the prop tips(metal), departed in
flight causing the damage. I think the length of the cracks and splinters on
the remaining prop blades argues against this. Even a lightweight taxi sign
shouldn't cause damage like this.
I haven't given up. I think the odds of that kind of symmetrical and
extensive damage occurring in flight are slim. I will feel better when I
find a piece of prop, somewhere on the airport.

Al



FOD walk the run up area...