what would ya use?..

swordfish · Post by **swordfish** » Tue Feb 24, 2009 2:50 pm

bus driver says:

The C-337 is a very nice airplane to fly as well

As long as the front engine is working...

glorified bus driver · Tue Feb 24, 2009 3:19 pm

haha Yah you need the front for heat I can't argue with that!

Airtids · Post by **Airtids** » Tue Feb 24, 2009 3:59 pm

swordfish wrote:bus driver says:
The C-337 is a very nice airplane to fly as well
As long as the front engine is working...

Actually,the thing performs better on the rear engine. Only problem is most have only a hydraulic pump on the front, so lowering the gear becomes an issue.

I repeat: C337 is NOT approved for FIKI, boots or not. Yes, there are Skymasters out there equipped with ice protection, but they er not APPROVED therefore can't be used for that operation on a commercial basis.

Tids

glorified bus driver · Tue Feb 24, 2009 4:26 pm

Airtids! You are quite correct that the 337 does operate better on the rear engine. Swordfish and I were kinda joking, If you lose the front engine you are going to get a little chilly! As far as flight in known icing it is prohibited but you still have the boots if you mistakenly find the ice!

North Shore · Post by **North Shore** » Tue Feb 24, 2009 4:39 pm

How about an F250 4x4 with a crew cab? Carry all of your guys + bags with room to spare. 4x4 would take care of ice/snow. You could buy a brand new one for the price of an old Aztec or 337, and there'd be no maintenance issues for some while. Fuel woud be a little cheaper, too.

Airtids · Post by **Airtids** » Tue Feb 24, 2009 5:19 pm

glorified bus driver wrote:Airtids! You are quite correct that the 337 does operate better on the rear engine. Swordfish and I were kinda joking, If you lose the front engine you are going to get a little chilly! As far as flight in known icing it is prohibited but you still have the boots if you mistakenly find the ice!

It's funny, I've lost the front engine on a 337 twice, and both times I found myself sweating!

goldeneagle · Post by **goldeneagle** » Tue Feb 24, 2009 5:29 pm

[quote="Ogee"I had the door come open on one at rotation at Pan Phillips ranch many years ago and it was a handful and more. It goes right out to the cowling and robs major air off the elevator on that side.
[/quote]

Oh gawd, that does bring back memories. I've had the door open on rotate departing yvr, and once out at a logging camp. The first time it happens, scares the living bejeesus out of you. Mechanics were argueing with me about it, so, i 'fixed that'. Couple days later, one of them was with me on an empty repositioning trip. I slowed it up, pretending I was going to show him an 'issue' with the gear, then 'accidentally' touched the door handle and it opened. Suffice it to say, after that, if the snag was 'door not latching properly', it was taken as a 'grounding' snag, not a 'we will look at it sometime later' kinda snag. I think that mechanic bought new shorts as soon as we got home

Funny thing too, he never would step into an aztec with me flying after that.

Never had the door open coming outa pan's place, but, i've gotta wonder now. Were ya headed in the direction of the trees? If memory serves correctly (hey, it's been 30 years), that was a bit of an upslope too, with terrain not to far downrange. Going the other way, easy left turn out over the lake.

Couple other things about the aztruck, the brakes. They got this stupid little hydraulic puck system, and if you wear the pads to far, the fluid can leak out around the puck. I used to 'blow the puck' at least once or twice a year. Did it once landing on the beach strip up in toba, good thing they built that one almost lined up with the road. I braked heavily on landing (had a load of drill bits on board), blew the puck on the left side. Not to big a deal, but I started using using full rudder and braking a little heavier on the right side, blew that one too. Ended up way down the road, even past the 'airplane turnaround' they had cut out there.

but, back to the issue at hand, it was never certified for known ice. So, even if you got one all dressed up with the hot plate window, full set of boots, and the hot props, you still cant take it commercially and file into known ice. So, no matter how good an airplane, it's no good for the original posters concept, which includes a need for running in ice.

mag check · Post by **mag check** » Tue Feb 24, 2009 5:56 pm

So the question then is, what is the cheapest small twin, that is known ice cert, and not as big as a pa31?

I don't think there is one.

'effin hippie · Post by **'effin hippie** » Tue Feb 24, 2009 6:05 pm

Mag Check x2

4 pax + 300lbs.

Night in known ice. Over terrain requiring some altitude?

Lots of peace of mind to be found in a straight 'Ho when a stove goes out.

That known ice requirement is gonna be pricy.

Cheers,

ef

/edit/ Isn't the BE55 approved for flight into known ice?

swordfish · Post by **swordfish** » Wed Feb 25, 2009 8:52 pm

A 'Ho does not carry ice as well as an Aztec. A 'Ho falls out of the sky with about an inch of mixed on it at about 115-120 if you're not careful on approach. An Aztec carries an inch without blinking...just a little slower. Also it does not accrete as fast as a 'Ho.

And regarding the 337...it is my opinion that the rear engine does not push as well as the front engine (I actually only have a few hundred hours on it, and none with one engine). The prop is shorter (in diameter than the front), it is in disturbed air, and the intake has to make a turn, unlike the front engine. It heats up more readily, and during training, the instructor usually pulled the front engine...I wonder why??? It flew like a pig on the rear engine, and we were always training "light" (gross weight). And when you popped the gear down, the drag from the doors and gear was "substantial". Almost full power to keep it level till the gear doors closed again.

We used it for fire patrol, but other than that, I think it's useless in commercial service.

And the bus driver was correct: when the front one quits (even during training) you freeze your buns off till the exercise is over...

Airtids · Post by **Airtids** » Thu Feb 26, 2009 11:22 am

swordfish wrote:it is my opinion that the rear engine does not push as well as the front engine

You may want to pull out your manual. The test pilots in Wichita beg to differ, and I happen to agree with them. I know it's weird, but pushers are more efficient than tractors. I'm not an aerodynamicist, so don't ask me why... Iflyforpie seems pretty knowledgeable about these things.

swordfish wrote:and the intake has to make a turn, unlike the front engine

swordfish wrote:when you popped the gear down, the drag from the doors and gear was "substantial".

I think you'll find that even at Vyse, full power, feathered prop, the machine is going down with partial gear. The manual shows that you'll go down about 100'/min faster with the front engine failed than the rear. See my first point above. I know this one caught a couple of geniuses departing out of CYGE a couple of years ago with the intention of 'airstarting' the engine they couldn't get to go on the ground.

swordfish wrote:We used it for fire patrol, but other than that, I think it's useless in commercial service

Absolutely agree with you on that one. Lousy charter machine, but excellent for all kinds of survey, not just patrol. The pod helps in the charter department. Be nice for a private guy too- unfortunately, I'm not in that tax bracket right now!

Tids

iflyforpie · Post by **iflyforpie** » Thu Feb 26, 2009 12:35 pm

Single engine performance in the Skymaster is good enough that if you leave the gear down you will still have a respectable (though not tremendous) climb rate in most cases. Useful to know if the front engine fails with the single hydraulic pump (on early machines) where selecting gear up will open the wheel doors and do nothing else (can we say drag?). Mods to remove the gear doors a la Centurion gets rid of a lot of headaches and doesn't cost you any speed.

The plane does perform better on the rear engine due to the high pressure area immediately ahead of the prop from the narrowing fuselage (Google pressure drag recovery) and the vena contracta effect (Google again) means the rear prop gets all the air it needs even with the fuselage in the way. It also doesn't have any obstacles behind it to reduce thrust. This is why the Rutan Voyager was designed to cruise on the rear engine only. Our Skymaster actually shows 1 inch higher on the rear engine at full throttle when cruising.

But I would agree with the others that it is not the best for large loads and ice.

The Aztec is a good solid twin, good in ice and is well built. But it sucks back the fuel without a corresponding payoff in speed (but only 100 miles right?) and is a maintenance hog.

The Beech Baron 55 adds about 10 kts to the Aztec and has plenty of power. This is what I would choose if a PA31 is too much. A 58 gives you more room, power, and another 10 kts.

swordfish · Post by **swordfish** » Thu Feb 26, 2009 9:35 pm

Well, iflyfprpie, I did Google "pressure drag recovery" and got no hits on it. There are hits for pressure recovery, and drag is mentioned elsewhere in the articles.

And as for "vena contracta effect", I see this discusses fluid dynamics through a restriction, but I don't understand how this would benefit the rear prop on a push-pull twin. Of the discussions I read (on Google), they all seemed to be based on a constant-pressure through the restriction and how the flow speed changes. This is not what happens around a body in free air, such as the top surface of a wing, or the body of the 337.

So I don't see how either of these 2 phenomena assists the rear prop developing more thrust per horsepower than the front one. Of course there's no denying Cessna's testing of the plane. Long time since I flew it...this is taxing my memory, dudes!

Now that you twig my memory, I do recall that it will fly much better with the gear down, rather than fiddling with it in transit.

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