Whirlwind 200RV Inspection Photos

ronschreck · #1 05-20-2009, 05:04 AM

I have been flying my RV-8 for three years and the 650-hour prop inspection was due. Yesterday I took off at dawn and flew to Austinburg, Ohio, home of Whirlwind Aviation and witnessed the inspection from start to finish. I was back home in North Carolina just as the sun was setting. I saved the $160 shipping fee and it cost me less than $100 in fuel to make the 5-hour round trip. The inspection costs $500 and after seeing all the work that goes into it, about 15 man-hours, I consider it a bargain. I wouldn't try this (the inspection) at home, but the experience sure gave me an insight into what makes this prop work.

I regularly outrun 200 HP RV-8's with my 180 HP mount and I attribute that advantage to the Whirlwind 200RV propeller. It is a marvel of engineering and the service provided by Greg Anderson and Paul Kershaw at the prop shop is unmatched. Thanks, guys!

Below is a link to a web album of 42 pictures of the inspection process:

https://photos.app.goo.gl/bjABvNHfyxmQEzS67

Guy Prevost · #2 05-20-2009, 07:58 AM

Very cool slideshow! It's nice to see what the inside of my prop hub looks like!

Guy

Bob Martin · #3 05-20-2009, 08:36 AM

Great post Ron.......Thanks for taking the time to do this.
The information is very good.
Makes me want a RV-200 prop more and more.

RV7Guy · #4 05-20-2009, 10:05 AM

Hi Ron,

Many know the benefits of WW and the 200RV for our airframes, smooth, light and efficient. Those 50 or so that took advantage of Group Buy will experience the same. 450 on mine now and going strong

You definitely can't go wrong with this prop and company.

Thanks for the slide show. I always wondered what was in there!!

erich weaver · #5 05-20-2009, 11:48 AM

I agree - great stuff from an area you rarely see or hear much about.

thanks!

erich

N130WN · #6 05-20-2009, 07:16 PM

Thanks Ron. Great pictorial. Looking forward to getting my prop in December...

mcencula · #7 05-20-2009, 08:04 PM

Ron,

One of your photos had the caption:

Quote:

Anybody know why this McCaulley hub design uses this cylinder ring and bolt spacers? Nobody at Whirlwind knows, either! But they are afraid to leave it off until they know what it's for. (Has to be a perverted engineer's joke.)

I believe the reason is to combat a phenomenon known as creep. Basically when bolting two plates together, the bolts stretch a little bit. This creates the clamping force. However, machined parts have a small bit of roughness on their surface as a result of the machining operation. This is known as the surface finish and is commonly specified by the engineers for critical parts. After being clamped together for some time, the peaks of the microscopic surface waviness get flattened out from being pressed on by the mating part. This means that the thickness of the part actually decreases slightly over time. This decrease in part thickness will cause a reduction in the clamping force on the bolts which can eventually lead to the bolts completely spinning loose. High vibration environments are especially prone to this problem.

The solution is to use longer bolts. Thus, for a given amount of clamping force, the bolts stretch a lot more. So a small reduction in stretch doesn't reduce the clamping force much.

Here's an example (my numbers are only for illustration):
Let's say you're using a 1/4" grade 8 bolt and you tighten it to half of it's ultimate strength (say, 1/2 of 150ksi or 75ksi). This means you're putting about 3680 lb of clamping force on this bolt. If the bolt is through a .063" thick steel cover plate, the strain is 75ksi/30msi or .0025. So over the clamping thickness, the bolt will only stretch about .0025 x .063" or .00015". Now, let's say a year goes by and the surface creep causes the thickness of the cover plate to be reduced by .0001". You've lost 66% of your clamping force! Very bad! And that's only .0001" inch of creep which is a really freakin' small amount.

Now if we use the same example, but instead of just the .063" cover plate, we also use a 15/16 thick spacer ring, the total bolting thickness is 1". The strain will be the same, but the bolt stretch will be .0025 x 1 or .0025". Now if a year goes by and the surface creep causes the thickness of the cover plate to be reduced by .0001", you've only lost 4% of your clamping force. Much better!

So, that, my friends is why there's a clamping ring. It would be very bad to omit such a thing.

Be safe!

ronschreck · #8 05-21-2009, 12:16 PM

Quote:

Originally Posted by mcencula

Ron,

One of your photos had the caption:

I believe the reason is to combat a phenomenon known as creep. Basically when bolting two plates together, the bolts stretch a little bit. This creates the clamping force. However, machined parts have a small bit of roughness on their surface as a result of the machining operation. This is known as the surface finish and is commonly specified by the engineers for critical parts. After being clamped together for some time, the peaks of the microscopic surface waviness get flattened out from being pressed on by the mating part. This means that the thickness of the part actually decreases slightly over time. This decrease in part thickness will cause a reduction in the clamping force on the bolts which can eventually lead to the bolts completely spinning loose. High vibration environments are especially prone to this problem.

The solution is to use longer bolts. Thus, for a given amount of clamping force, the bolts stretch a lot more. So a small reduction in stretch doesn't reduce the clamping force much.

Here's an example (my numbers are only for illustration):
Let's say you're using a 1/4" grade 8 bolt and you tighten it to half of it's ultimate strength (say, 1/2 of 150ksi or 75ksi). This means you're putting about 3680 lb of clamping force on this bolt. If the bolt is through a .063" thick steel cover plate, the strain is 75ksi/30msi or .0025. So over the clamping thickness, the bolt will only stretch about .0025 x .063" or .00015". Now, let's say a year goes by and the surface creep causes the thickness of the cover plate to be reduced by .0001". You've lost 66% of your clamping force! Very bad! And that's only .0001" inch of creep which is a really freakin' small amount.

Now if we use the same example, but instead of just the .063" cover plate, we also use a 15/16 thick spacer ring, the total bolting thickness is 1". The strain will be the same, but the bolt stretch will be .0025 x 1 or .0025". Now if a year goes by and the surface creep causes the thickness of the cover plate to be reduced by .0001", you've only lost 4% of your clamping force. Much better!

So, that, my friends is why there's a clamping ring. It would be very bad to omit such a thing.

Be safe!

You win a cupie doll! Seems you are 100% correct. I forwarded your post to Greg Anderson at Whirlwind and he admitted that you are right. He didn't initially tell me the reason for the ring because he figured that was a trade secret.

gfb · #9 12-30-2018, 12:14 PM

Sorry to revive an old thread, wondering if this album is still available elsewhere now that picasaweb has been shuttered.

Thanks!

ronschreck · #10 12-30-2018, 05:31 PM

Quote:

Originally Posted by gfb

Sorry to revive an old thread, wondering if this album is still available elsewhere now that picasaweb has been shuttered.

Thanks!

All of the photos are available on Google Photo but the captions have been lost. (No. Read the PS.) If you have any questions I'll try to recall the details. Here's the link:

https://photos.app.goo.gl/bjABvNHfyxmQEzS67

PS: Click on the first photo to enlarge to full screen and the captions are at the bottom of the photo. Scroll through the full size photos with the arrow on the right margin.