To P or not to P, that is the question

[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/

[Red Air Rambo]

You might want to price the Riley air conditioner...I don't know about the cost but it works great.

[edasmus]

My 2 cents on the Arctic Air (cooler) air conditioner... I purchased one of the larger ones at Oshkosh a few years ago. It works as advertised, which is to say it does a good job keeping the cabin cool.

The preparation work is the problem. Stopping at the gas station on the way to the airport to buy several large bags of ice, getting it all loaded, lifting 50+ pounds into a sweltering C337 cabin and securing it, and by now one is totally drenched in sweat. Not fun.

Realistically about 45 minutes to an hour of cool air is what you get with my unit. Which will get you up and down assuming it is turned off at altitude. If you have a multi-leg day, a re-load is necessary assuming you can get the ice at the airport you happen to be at and then you get to enjoy that preparation work once again.

I try very hard not to use my unit because of all this and actually have not used it in 2 or 3 years now. If I was really motivated for a particular flight and it was 95 plus degrees, I would probably use it but generally if it is that warm outside, I try to avoid flying. You may not have that option however, so the prep work may be worth it to you.

Good Luck,
Ed