Beaver Air Intake

[wonger]

Always been fascinated with the Beaver (pun intended ), so I surfed some images on the web.

Came across this pic, which shows two air intakes on the bottom. Obviously I haven't been around the DHC2 much, nor have spoken to any pilots about the plane;

So, my question is: Which one is the air intake for the engine (I'm guessing the small one directly underneath the cowling)? What about the larger one aft of the cowling?

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[Bushav8er]

Larger one at rear is oil cooler.

[bigredone]

The example picture indicates a civilian model with the air intake on the lower cowl. Ex-military versions will sport an air intake on the upper left looking from the drivers seat.

[Bushav8er]

The example picture indicates a civilian model with the air intake on the lower cowl. Ex-military versions will sport an air intake on the upper left looking from the drivers seat.

On the right from the drivers seat

[wonger]

Thanks for your input guys. A little less scratchin on my part for underneath the bird, BUT - I thought the vent/opening on the top right of the cowling was a cooling intake for the generator??

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[mr.jinks]

That's a cooling intake for an alternator stc. the upper cowling intake on military beavers is much larger, I think it was put there for desert operations to minimize sand/fod damage. could be wrong though.

[iflyforpie]

This is the Army style intake. Much larger than the generator/alternator cooling intake. Note that the scoop on the bottom cowl has been deleted.

[Rowdy]

The desert scoop (up top) could be ordered on civilian models as well.. and a few have been converted.. so it's not the best indicator. You'll also notice that there are a couple of different lower scoops, If I remember right it was based on build date and carb choice.. And if you wonder why some throttle quadrants are prop power mixture and some are the L20 Power prop mixture (normal)



This machine has the upper intake (desert scoop) AND the cooling tube for the alternator.



ODO here has the lower scoop.

The pics you've shown show the other style of lower scoop as well. Hope that helps clear things.

[wonger]

Thanks again for all the great info -

[bigredone]

Been so long since I sat in a Beaver I am just glad I didn't mistake it for a Twin Otter. How about this one then, single dorsal fin versus dual tip mounted fins? Besides making it harder(not impossible!!) for me to rip one off on the dock what's the story?

[beaverbob]

The example picture indicates a civilian model with the air intake on the lower cowl. Ex-military versions will sport an air intake on the upper left looking from the drivers seat.

Upper right

[beaverbob]

Been so long since I sat in a Beaver I am just glad I didn't mistake it for a Twin Otter. How about this one then, single dorsal fin versus dual tip mounted fins? Besides making it harder(not impossible!!) for me to rip one off on the dock what's the story?

Single dorsal fin is DeHavilland original for floats and tip mounted fins are STC by Kenmore in Seattle.

[mr.jinks]

the dual fin is part of the water rudder stc by kenmore, allowing for better water handling, if you look underneath the plane, you will see a torque tube that extends down from the air rudder and actuates the water rudders via cables. On the original design, the water rudder cables hook up directly to the rudder peddle linkage directly under the pilots side at the front of the cabin just behind the firewall. You will also find other "visible" stc's on beavers, such as;
-cabin extensions, look for the extra square windows aft of the rear door. these include locating the battery forward of the firewall.
-Alaska doors, A large door aft of the cargo door on the pilots side
-Firewall extensions, extends the engine forward of the firwall by 5 or 6 inches ( or something like that ) to help with aft c of g problems when loading
-a few different props, huge ag props, long props, short props, 3 bladed props.
-lots of different floats, the most common being edo 4580's and 4930's
-wipaire does a pt-6 conversion to standard beavers, obvious visually of course
-PZL 600hp beaver conversion, look for the bigger cowling and 4 blade prop
- baron stol kit, i believe is a leading edge cuff and drooped wing tips
- some up gross stc's have tip tanks, and you can see the fuel caps on the upper outboard edge of the wing
- some have a straight exhaust stack, others have the long exhaust that goes about 3 or 4 feet back on the passenger side, this is for cabin heat, since most beavers only operate in the summer, most have them removed.


im sure there are a bunch more visible mods, but generally, a beaver is a beaver. windshield wipers would be nice.

[Slats]

-a few different props, huge ag props,

Is that the big fat 2 blade square tip prop? I flew one with such a prop and never bothered to research what kind of prop it was, but it is considerably bigger than the stardard little 2 blader. Doesn't do much for cruise but pulls like a son of a b!tch off the water!

[mr.jinks]

not sure, Im no expert. I just wrote down difference i have noticed over the years. beaverbob would be the guy to ask

[sarg]

-a few different props, huge ag props,

Is that the big fat 2 blade square tip prop? I flew one with such a prop and never bothered to research what kind of prop it was, but it is considerably bigger than the stardard little 2 blader. Doesn't do much for cruise but pulls like a son of a b!tch off the water!

Most likely was an ag prop, but the ones we ran had the round tip. They required a little more maintenance and a little more care in taxing do to engine vibration, if the memory is still working. The whole point of the ag prop is the pull off the water, up and out of the rough water fast.

[beaverbob]

The wide blade is an agriculture prop. They can be round tip or square tip. Very little difference in performance. They do have the best take off and climb performance. I had both on GSKY but the sqare tip vibrates much more than the round tip and shakes the dickens out of the engine as power is applyed through the 700 to 800 RPM range. They are the same prop, just cut off to length differently by the prop shop.
BB

[Slats]

That makes sense, thanks beaverbob. I always had to avoid operating around 800 RPM because as you said, it would really shake the hell out of the front end and worry any passengers on board. Still much prefered it to a 3 blader though, no comparison in take-off performance.

[Rowdy]

All the beavers I've flown have had different props. The BIG round tip 2 blader (ag prop I was told) was the quickets feeling off the water and you're spot on about the rumble at 700-800rpm. At first I thought a mount was broken

Curious to know what the 6000lb upgross STC has involved with it?

[Slats]

Probably strut cuffs, tip tanks and a PT-6