To P or not to P, that is the question

[JimC]

I'm resurrecting this thread because it's the exact question I have. I'm a potential P337 buyer, but probably not until later next year. The reason I'm asking now is that I can make it to Groton, but if I decide not to get a P337 there are a few other unpressurized planes that I might choose over the 337 and attending this year becomes less of a priority.

Some of the reasons I think I need a P337:
I frequently visit short strips (2200' paved with no obstructions, 2500' paved with trees one end, 2900' grass w/ no trees - all less than 1000'MSL elevation.) The bulk of my flying is north of 40deg latitude. I have a 4x/year route that goes south around/thru JFK/LGA, PHL, BWI and DCA and the deviations I get are horrendous. From what I've heard if I can get to 15K or higher I'll get much straighter routing. I've been routed over 150nm off course in a single flight. I won't go out over the water in my single and it does poorly above 12,000'. I'm also sick of picking my way through local summer weather at 9,000-11,000 ft. My wife gets headaches if not on O2 above 10-12K and neither of us are fans of the nosebag.

So onto my specific questions. I have searched the site and read 100's of messages, but I still have an unanswered question or two:

1) Re: Cabin temp with pressurization. Can you turn off the pressurization until you're at altitude to keep incoming fresh air temps down? Can you bypass the pressurization intake and get direct fresh air? If so, is there any problem with turning pressurization on suddenly at altitude? If not, how much above outside air temp do you see the cabin temps during climbout?

2) How much do the intercoolers help with incoming cabin air temps? If you can estimate an actual temperature diff in degrees F that would be great.

3) If you have a P337, what's your actual empty weight? What have you added that bumped it up significantly? What's the lowest empty weight I'm going to realistically find on a P337 without AC?

4) What are the differences between the 73-77 T337G (I think this is the official Cessna code for the early pressurized aircraft) and the 78-80 P337H? For some reason this is tough to find. It's often listed as "minor changes." I have found differences by manufacturing year (seat rails, tanks) but not by model letter.

So, please - talk me out of a pressurized plane!

Thanks for your help,

Jim C

[JimC]

No replies? Was it too many questions?

Let's just try one line of questioning:

How much does your Turbo or Pressurized 337 actually weigh empty? What's the gross? What's your year & model?

I can find the book figures; I'm interested in real-world answers. I have yet to fly a plane from any manufacturer that's actually as light as the factory numbers.

[Dave Underwood]

I will be back in my office in the next day or two and will pull my latest wt & bal and have a look at my various manuals to try and answer some of your questions.

D

[bjherron]

1) Re: Cabin temp with pressurization. Can you turn off the pressurization until you're at altitude to keep incoming fresh air temps down? Can you bypass the pressurization intake and get direct fresh air? If so, is there any problem with turning pressurization on suddenly at altitude? If not, how much above outside air temp do you see the cabin temps during climbout?

Yes, you can turn on pressurization in flight. I wish my 73 T337G Pressurized had AC though. It can get warm at takeoff and landing. It is fine up high. I may try one of those ice coolers.

2) How much do the intercoolers help with incoming cabin air temps? If you can estimate an actual temperature diff in degrees F that would be great.

I don't know, I do not have an IC

3) If you have a P337, what's your actual empty weight? What have you added that bumped it up significantly? What's the lowest empty weight I'm going to realistically find on a P337 without AC?

3172.7 is my empty weight. Full of gas that leaves about 735lb for max takeoff, but landing weight is lower. Also, you have to be inside the arm/moment envelope, which makes it tough to actually use all of that weight.

4) What are the differences between the 73-77 T337G (I think this is the official Cessna code for the early pressurized aircraft) and the 78-80 P337H? For some reason this is tough to find. It's often listed as "minor changes." I have found differences by manufacturing year (seat rails, tanks) but not by model letter.

I have a 73 T337G. I am not sure what the changes are.

[JimC]

bj,

Can I bother you with a few followup questions?

re: Warm during takeoff and landing - What's your latitude where you're based? Where do you do most of your flying?

re: tough to use all 735lb - Do you usually find yourself too far forward or aft of the cg?

Does anyone know if the cg location of the earlier long range tanks is about the same as the later 148 gallon tanks?

Thanks,

Jim

[bjherron]

Jim,
No problem at all. We are based in Michigan. Today we flew from STL to ARB in MI. It was 90 - 95F at both airports. Passengers were sweating on takeoff and landing, but very comfortable at 17,500 where we were cruising with a ground speed of 215-220. Whole trip was just under 2 hours, something that few light twins can do.

The heat is my only complaint, and we're going to order one of those ice coolers next week to make things better. I haven't had the plane long enough to know how it is during winter, but I suspect it will be MUCH better.

For the CG, it's always near the forward edge. But then again I am 6'5 and my instructor is also 6'. Plus we are always flying with full tanks.

I spent a lot of time looking, it's hard to beat this without spending a lot more on the plane and gas.

[James Bennon]

BJ, keep us posted as to your purchase of a "cooler" for your P337G and how it performs. We also have a 73 P337G and have been considering the same purchase.

JB

[JimC]

It seems that a large winter Arctic Air setup weighs about the same (67lbs) as factory A/C. It can be removed when you want the space & weight in winter, but it also needs to be refilled.

For those of you considering the Arctic Air coolers - do you wish you had factory A/C?

http://www.arcticaircooler.com/

[hharney]

Originally Posted by JimC

4) What are the differences between the 73-77 T337G (I think this is the official Cessna code for the early pressurized aircraft) and the 78-80 P337H? For some reason this is tough to find. It's often listed as "minor changes." I have found differences by manufacturing year (seat rails, tanks) but not by model letter.

So, please - talk me out of a pressurized plane!

Thanks for your help,

Jim C

I would suggest that you read these posts from Dennis Hamblin of Flint Fuel Tanks. There is a post that describes the differences in the wings of P model Skymasters.

http://www.337skymaster.com/messages...earchid=585613

[JimC]

Herb,

That link bring up a "Sorry - no matches" page for me. Do you have another link?

Jim

[James Bennon]

Herb, kind of off subject but do you know of the feasibility of converting the rear seats of a 73 P model from fixed position to sliders?

JB

[hharney]

Originally Posted by James Bennon

Herb, kind of off subject but do you know of the feasibility of converting the rear seats of a 73 P model from fixed position to sliders?

JB

Sorry James I do not. It sounds like it would require a field approval. It may not be impossible because the P model had the slider seat later in the manufacturing run. Not sure if the H model was the first or if there were G models with the slider?

Good Luck

[JeffAxel]

I think the slider seat started in the '75 P models. My '77 had it. The fuel tanks also changed in the '75 models with long range fuel going to 148 gallons, no tank switching except to cross feed.

[James Bennon]

Thanks Jeff, I need to find someone that has installed later model rear seats in a 1973 P model to establish whether it is possible.

JB

[hharney]

Originally Posted by JimC

Herb,

That link bring up a "Sorry - no matches" page for me. Do you have another link?

Jim

Try this and click "find all posts by ....."

http://www.337skymaster.com/messages/member.php?u=13445