Center Window Post deletion - your thoughts?
 

Members,
I am currently in the process of replacing all my windows (1966 A model) and I am contemplating moving forward with eliminating the windshield center post. It appears to be a great mod (STC) and well engineered - no doubt. I have gone back and read a lot of past discussions on the subject of eliminating the center post, but I am looking to get a new take on if anyone finds any value in this from a Pilot's perspective? I am not concerned with the cost, STC or doing the work, but the biggest thing I am trying to figure out, is does the removal of the center post actually help with visibility that much, or do people look at this more as a cosmetic benefit? I am also troubled that I would need to find a new location for the compass, and likely that would be on the glare-shield/dash and potentially just moving an obstruction that is normally higher in the line of sight, to more at the horizon and causing even more obstruction than where it was before.

Please let me know your comments and thoughts - thank you!
Jeff

Jeff, I can't see any benefit to eliminating it? I don't have any issues seeing out the front.

Thanks
 

Thanks John for the quick response! Also, keep up the photos and videos on the Facebook page; they are great!!
Jeff

On the other hand
 

For perspective, I was a helicopter owner/pilot first. So transitioning to fixed wing for me was like learning to drive a submarine. All that stuff in the way out front. Cant see anything.

One of the reasons I liked the 'thrasher was at least the sides were wide open. Your head is ahead of the wing, so side view is basically unobstructed.

That said, I think the one piece out front makes a HUGE difference.

When mine was done a thousand years ago, it was time to replace the windshield because it had become so hazy. One particular landing into the setting sun had been like Lindbergh landing in Paris. I had to look out the sides to decide when to flare. That was it.

Being a relentless nerd, I did some research.

The original 337 windscreen is/was very thin, light, (weak) Plexiglas. I don't recall the thickness, but it was very thin. It was and remains today a single piece, with a center bracket for support. (That is of course after first weakening the windshield by drilling holes in it for the center support bracket!). So the old super thin Plexiglas definitely needs support.

When I was exploring this, there were still some old timers at Cessna very familiar with the airframe and testing. Cessna told me the original windscreen was thin Plexiglas, for weight and optics, because that's what they did back then. Any thicker would get heavy and wavy.

They also noted that the most sound reduction in any aircraft came from going thicker on the front window. Apparently lots of experience with single piece conversions on C210, 182 etc. Reduces the beat of props, wind, etc.

So I went with the thickest windshield I could get installed, and have never looked back.

And yes, it is a LOT quieter, and I MUCH prefer the unobstructed view.

From a helicopter pilot's perspective there is STILL that front engine, prop, and all those gauges in the way, but I've got used to it.

My T337D is NOT pressurized, which might be another factor to consider. Commercial jet windows blow OUT.

If you see how the window is installed, if done correctly it is NOT coming out. Nor if using modern thicker plastic is it ever going to break.

One of our based pilots, Alfonso, also on this board, researched this extensively before doing same with his 336. He was a former FAA inspector and could find zero incidence of any windshield issues or failures. That said, he did the STC and managed to hit a bird, or went into a thunderstorm and THEN hit a bird, so the window broke!

So don't do that.

Another strategic trick is I have the airplane tied down outside facing NORTH. Why? Well, the wings are facing SOUTH, so de-ice faster in the winter, AND the sun's angle of incidence on the modern Plexiglas is slight.

High end auto restoration friends had also told me to never use a cover, because they tended to accumulate grit underneath that ground the surfaces beneath in the wind.

After more than 20 years since the windshield was replaced, tied outside continuously in Washington summers and winters, with no cover, it is almost as clear as new.

The STC may actually be just one of those STCs designed to require you to pay them money for a piece that effects nothing. I would look into the actual history of issues, if any, then decide.

So far so good.

Nice writeup by LP Aeroplastics
 

http://www.lpaero.com/images/cessna1.html

The Original Cessna Design: The center strap provides positive retention of the windshield at the top of the cabin. Positive retention in channel is necessary because this area operates in a negative pressure environment and could "pop out" if not positively retained.

Windshield thickness increases are implemented where the original windshield was 1/8" or 3/16" thick.

So there!

Thicker window
 

Hi David,
Thanks for your feedback and data. I am curious to know the mod you have for the thicker window? I can only find data that reflects Cessna 337 windshield is 0.250 thick, and that is the only thickness I have found for replacement. The STC I am looking at does provide retention at the top and bottom of the window in the center portion, but does not include the windshield, just the sheet metal plates for reinforcement. Any guidance on where the thicker windshield could be acquired?
Thanks,
Jeff

One source for 0.25 windshield
 

It's been a million years since mine was done, but here is one source.

http://www.glapinc.com/Cessna/337/337a.htm

Here is a refence for what they originally used on C170s.
As I recall, the original on my '69 'thrasher was also super thin.

"The original windshield was 1/8" thick thereby needing the aluminum center strip(IPC 051000-16) down the center (giving rise to the erroneous "two-piece" name). Any thickness windshield you buy can be tinted. If you select the 1/8"thickness you must use the support strip. If you order the 3/16" thickness you may opt to leave off the strip*. You may not be able to install the new windshield an easily without drilling off …"

http://www.cessna170.org/forums/viewtopic.php?t=554

And another interesting article:

https://www.avweb.com/news/features/...-225181-1.html

When replaced, my original windscreen was the original, 1968 installed at Cessna. When I replaced mine I purchased from Great Lakes Aero Products and it was the same thickness as original. That was the only option, no option for thickness as I have never seen an STC for thicker windscreen. Saying that I would not be surprised if the 336 had a thinner windscreen and when Cessna designed the 337 they settled on what we have today. Mine is a "C" model so I could be referring to only up to a certain serial number. On GLAP website it lumps serial number 2 - 1426 as all the same replacements. I kept my center strap because I was told it was there to hold the top of the windscreen because if enough stress is on the fuselage it could pop out. After struggling for hours, days trimming and fitting the new windscreen I found that there is really not a whole lot holding that windscreen in place at the top. Of course today's Pro-Seal is probably stronger than the old sealant that Cessna used I still kept the center strap. Besides I like my compass suspended. I have seen several center strap deletions and they do look nice.

Please do not use Silicon Sealant on your windows. Pro-Seal is the only way to go

Thanks
 

Thank Herb for your info and to Dave as well for the follow up. I have made the decision to just stay with the center strip and keep things original. Probably because I am struggling to see any large benefit over the additional work and cost of the STC mod. I think the mod is good, but I am very used to VFR flight looking through center strips and v-braces on my Stinson.

If I have time, I will try to post a bit after I finish this job. I am replacing all the windows and just ordered them today from Great Lakes Aero Products (GLAP). Clear on the Windshield and grey tint on the rest of the outer windows. The Windshield from GLAP is the same as my original at 0.250" thick (1966 C337A). Having replaced windshields in Boeing 737s and Lockheed Hercules, this one should not have many surprises - however I can see some time spent fitting will be required. I am planning at this point to install much like Cessna did at the factory - use the felt and the Presstite Sealer - but finish seal the exterior trim with PRC.

Thanks everyone for your thoughts - and keep them coming!
Jeff

Center Window Post deletion - your thoughts?
 

JAG. FYI, I have 1965 C337 and the wind shield was replaced a year before I bought it. It has the center support post and I don't see any problem with that. BUT A WORD OF CAUTION-please be sure to over size the holes in the wind shield to prevent cracks in the glass. The A&P and previous owner did not and there are two small cracks, that I had to repair, in the hole for the compass. I also see a benefit to having the post so the Compass and OAT gauge has something to mount to. I replaced the whiskey compass with a vertical card but I did have to drill an extra hole through the support and wind shield. By removing the old compass mount the extra hole was needed because the Vertical card compass had to be moved upward for clearance.
Regards, BILLS

drill size
 

Bill,
Yes - thanks for the reminder on the drill size. I was planning to drill the holes 1/4" for the 3/16" screws (1/16" larger) - I think the general rule of thumb is to make the hole 30% larger. I too have the Vertical Compass with a nice mount, and that is a big reason I am sticking with the center strip as this (and the OAT) mounts so nice already and saves me having to make a new dash mount.

Thanks again for the feedback.
Jeff

Center Window Post deletion - your thoughts?
 

JAG. Thanks for the reply. Hope yours comes out better than mine.
Regards, BILLS

What a view
 

I went with vertical card compass mounted on glare shield.

Keeps everything nice and open,

It's the former helicopter owner/pilot in me.