PBY speed same with floats up or down?

Stephan Wilkinson · **Joined:** Wed Jun 01, 2011 11:23 am **Posts:** 699

Roscoe Creed, in his book "PBY: the Catalina flying Boat," claims that whether the wingtip floats were extended or retracted, the aircraft's airspeed remained the same. Can anybody with practical experience say whether this is possible? That's a lot of struttage to stick into the airstream when the floats are down, and it sounds hard to believe that it wouldn't slow the airplane down a bit.

(Apologies for my every-other-day PBY questions. I'm working on an Aviation History Magazine cover story on the airplane, and I want to gets it as right as I can.)

David Legg · **Joined:** Sun Dec 31, 2006 1:07 pm **Posts:** 338

It makes negligible difference to speed but there is noticeable yaw as the floats come down which has to be counteracted.

JohnB · **Posted:** Sat Jul 14, 2012 6:28 pm

Stephen...
Here's a PBY question for Peter Garrison....
With the floats up, would the wing have better short-field capabilities because of the (albeit minor) end-plate effect caused by the wider floats?

The Inspector · **Posted:** Sat Jul 14, 2012 7:50 pm

JohnB wrote:

Stephen...
Here's a PBY question for Peter Garrison....
With the floats up, would the wing have better short-field capabilities because of the (albeit minor) end-plate effect caused by the wider floats?

Yeah, but you'd need to add more flap :lol:

SaxMan · **Posted:** Sat Jul 14, 2012 9:46 pm

PBY Airspeed, floats down = Slow

PBY Airspeed, floats up = Slow

PBY Airspeed in just about any attitude except straight nose down = Slow

PBY Airspeed, nose down = maybe a little bit faster than just Slow

Actually, the PBY is one of my favorites and it's contribution to the war effort is often unappreciated. Few planes possessed its versatility and reliability under all kinds of adverse conditions.

David Legg · **Joined:** Sun Dec 31, 2006 1:07 pm **Posts:** 338

The Inspector wrote:

JohnB wrote:

Stephen...
Here's a PBY question for Peter Garrison....
With the floats up, would the wing have better short-field capabilities because of the (albeit minor) end-plate effect caused by the wider floats?

Yeah, but you'd need to add more flap :lol:

What flaps? :lol:

The Inspector · **Posted:** Sun Jul 15, 2012 7:22 am

David Legg wrote:

The Inspector wrote:

JohnB wrote:

Stephen...
Here's a PBY question for Peter Garrison....
With the floats up, would the wing have better short-field capabilities because of the (albeit minor) end-plate effect caused by the wider floats?

Yeah, but you'd need to add more flap :lol:

What flaps? :lol:

Precisely

B25PBYGUY · **Posted:** Sun Jul 15, 2012 11:12 am

7 kts off cruise speed, and aileron authority noticeably compromised.

I needed something to do while sitting here with movie Memphis Belle in the rain at Geneseo,

Chuck Giese · **Posted:** Sun Jul 15, 2012 11:31 am

B25PBYGUY wrote:

7 kts off cruise speed, and aileron authority noticeably compromised.

I needed something to do while sitting here with movie Memphis Belle in the rain at Geneseo,

How can it be raining there when I'm in Florida?

David Legg · **Joined:** Sun Dec 31, 2006 1:07 pm **Posts:** 338

B25PBYGUY wrote:

7 kts off cruise speed, and aileron authority noticeably compromised.

I needed something to do while sitting here with movie Memphis Belle in the rain at Geneseo,

I just took what was meant to be a quick look at the RCAF Training Command Canso Flying manual dated March 1959. It turned into a long read but it quotes approx 5 knots and aileron control appreciably reduced so that ties in with the above.

Dave Hadfield · **Joined:** Sun Sep 17, 2006 10:31 pm **Posts:** 1672

In the book "North Atlantic Cat" by Don McVicar, he describes numerous very heavy takeoffs. The floats reduced performance while getting off the water. Obviously they were needed at the beginning of the run. As soon as the speed on the takeoff run had got to the point where the ailerons had authority, and the wingtip floats weren't needed, they retracted them. I believe there was probably a small increase in lift as well as a reduction in drag, helping them get off the water when fully loaded for a ferry flight across the Atlantic (Bermuda to Portsmouth).

Of course a rejected take-off after that point could be problematic...

Dave

cwmc · **Joined:** Fri Jan 28, 2011 2:43 am **Posts:** 322

Don McVicar was a god!
Chris...

CoastieJohn · **Joined:** Fri Feb 11, 2011 5:37 pm **Posts:** 1380

Recall the USN PBY that flew off the ice cap in Apr '43. What some folks didn't know was the engine problems they had trying to do it. They didn't get airborne the first run down the ice. Somewhere in their numerous take-off attempts, they had an engine fire. The mechs were able to do a temp fix and when the wind picked up the next day, they finally got enough lift to get airborne. I believe they came into BE-2 single engine as the temp fix on the other engine was no longer temp and they were low on fuel. I have a first person account of that.

BAJ · **Joined:** Wed Jan 25, 2012 3:14 pm **Posts:** 126

Dave Hadfield wrote:

In the book "North Atlantic Cat" by Don McVicar, he describes numerous very heavy takeoffs. The floats reduced performance while getting off the water. Obviously they were needed at the beginning of the run. As soon as the speed on the takeoff run had got to the point where the ailerons had authority, and the wingtip floats weren't needed, they retracted them. I believe there was probably a small increase in lift as well as a reduction in drag, helping them get off the water when fully loaded for a ferry flight across the Atlantic (Bermuda to Portsmouth).

Of course a rejected take-off after that point could be problematic...

Dave

Lifting the wing floats as soon as the wings and ailerons were working during take-off was pretty well standard RAAF practice....there are many good photos of the practice and talking to war vets they claimed it did help the take off run

CoastieJohn · **Joined:** Fri Feb 11, 2011 5:37 pm **Posts:** 1380

CoastieJohn wrote:

Recall the USN PBY that flew off the ice cap in Apr '43. What some folks didn't know was the engine problems they had trying to do it. They didn't get airborne the first run down the ice. Somewhere in their numerous take-off attempts, they had an engine fire. The mechs were able to do a temp fix and when the wind picked up the next day, they finally got enough lift to get airborne. I believe they came into BE-2 single engine as the temp fix on the other engine was no longer temp and they were low on fuel. I have a first person account of that.

Plane mentioned above....

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PBY speed same with floats up or down?

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