Rudder flight modeling

[earl1937]

The very large vertical stabilizer on the B-17E, F and G was added due to insufficient directional stability at high altitude for accurate bombing.  The B-29's vertical stabilizer was large to start with based in prior experience with the B-17 series.

My friend, hate to disagree with you, but since you brought it up about the vertical stab and rudder, the size of which is dictated by the VMC, with 2 engines out on one side! The larger the rudder is, the lower the VMC with 2 out on one side. Has nothing to do with high altitude bombing! The dosal fin area was added to enhance stability in all flight realms in the E, F and G series, along with other improvements in the aircraft in general.

[colmbo]

Directional stability has a lot to due with bombing accuracy.  The flying wing bombers (YB-35 and YB-49) both scored very low in bombing accuracy due at least in part to yaw instability.

I've read the big tail on the B-17 was added to improve stability in yaw, even so the airplane still wags it's tail quite a bit...at speeds well above Vmc.

[earl1937]

Directional stability has a lot to due with bombing accuracy.  The flying wing bombers (YB-35 and YB-49) both scored very low in bombing accuracy due at least in part to yaw instability.

I've read the big tail on the B-17 was added to improve stability in yaw, even so the airplane still wags it's tail quite a bit...at speeds well above Vmc.

You could be right! Would be very interesting to read engineering notes of flight crews who tested the 17 and 29. You fly an aircraft which always, or I have been told in the past, had directional problems with the loss of 2 engines on one side. The U.S. Navy was very interested in the B-24 as a anti-submarine patrol aircraft, but because they spend a lot of time "low and slow" in their normal duties, they elected to go with the single vertical stab and rudder, again concerned about the VMC with 2 out on one side.The Privateer was externally similar to the Liberator, but the fuselage was longer to accommodate a flight engineer's station, and had a tall single vertical stabilizer rather than the B-24's twin tail configuration. The defensive armament was also increased to 12 .50-in (12.7 mm) M2 Browning machine guns in six turrets (two dorsal, two waist, nose and tail), with the B-24's belly turret being omitted. Turbosuperchargers were not fitted to the engines since maritime patrol missions were not usually flown at high altitude.
 
The Ford Motor Company (which produced B-24s for the United States Army Air Forces) had earlier built an experimental variant (B-24K) using the single tail of a B-23 Dragon.[2] Aircraft handling was improved, and the Air Corps' proposed B-24N production model was to be built by Ford, but the order was canceled on 31 May 1945 and the B-24N never entered production. The Navy's desire for substantial redesigns, however, had sustained interest in the new tail assembly.
 
The Navy eventually took delivery of 739 Privateers, the majority after the end of the war, although several squadrons saw service in the Pacific theater in the reconnaissance, search and rescue, electronic countermeasures, communication relay, and anti-shipping roles (the latter with the "Bat" guided bomb.)
Being a B-24 pilot yourself, I am sure you can appreciate concern about the "moment arm" of the rudder in the vertical axis! But anyway, was an interesting thread! To bad we can't have more discussions like this..Brings back a lot of memories when learning the ins and outs of the old 29C.

[colmbo]

Unfortunately the WWII era manuals on the airplanes didn't have nearly as much info as a modern POH has.  For instance for both the B-17 and B-24 there is no Vmc listed.  In the B-24 book the section on two engines out on takeoff starts with "This shouldn't happen to a dog!"  While I agree with the statement it doesn't give the pilot a lot of info on how to handle the problem.  I think in large part some of the numbers simply weren't known, testing had not been as detailed as it is today when aircraft are certified.  Quite probably neither would be able to be certified today as a civil aircraft, they each have some flight characteristics that today wouldn't be tolerated.  (stall characteristics, adverse yaw, roll performance to name a few)

[hitech]

Anyone ever had their feet hurt the next day after flying around thunderstorms for a few hours?

The top of my right foot is killing me today.

HiTech

[Midway]

Anyone ever had their feet hurt the next day after flying around thunderstorms for a few hours?

The top of my right foot is killing me today.

HiTech

Might I suggest an alternative... There is this cool game/flight sim without thunderstorms that lets you...

Um.... nvm.  

[earl1937]

Unfortunately the WWII era manuals on the airplanes didn't have nearly as much info as a modern POH has.  For instance for both the B-17 and B-24 there is no Vmc listed.  In the B-24 book the section on two engines out on takeoff starts with "This shouldn't happen to a dog!"  While I agree with the statement it doesn't give the pilot a lot of info on how to handle the problem.  I think in large part some of the numbers simply weren't known, testing had not been as detailed as it is today when aircraft are certified.  Quite probably neither would be able to be certified today as a civil aircraft, they each have some flight characteristics that today wouldn't be tolerated.  (stall characteristics, adverse yaw, roll performance to name a few)

You sir, are correct about the lack of fully exploring the flight envelope of new aircraft, back in the old days! Fortunately, we now have "wind tunnel" testing to establish those "V" numbers. I do recall an old gentleman, who starting flying the mail in the early 30's, then the "hump" for about a year, then was transferred to a B-24 outfit operating out of Queensland, Austrialia, talk about establishing some minimum flying speed IAS. If I recall correctly, if they weren't at the "number", the plan was to crash straight ahead with wings level, rather than roll inverted over the runway and ending upside down on the pavement. From some of the comments I used to hear from the old heads, who flew 17's and 24's in the big war, handling at slow speeds with full loads was at best a "crap shoot" sometimes because of the short field lengths they had to work with back then. There was never any consideration for a "balanced field length" or accrearate and stop distance computations until the B-29 came along. Anyway, there had to be some interesting situations during the WW2 area, because they learned a lot of things by trail and error. Not a good development program!!!

[colmbo]

Anyone ever had their feet hurt the next day after flying around thunderstorms for a few hours?

The top of my right foot is killing me today.

HiTech

You whack it on the bottom of the panel in a downdraft?

To answer your question....No.

[hitech]

You whack it on the bottom of the panel in a downdraft?

To answer your question....No.

On bumpy days the RV likes to wag its tail, holding the rudders solid stops this. But on days where I am not just sitting back monitoring and looking for airplanes, some times my feet will be pushing hard on the rudders holding them, with out me realizing it.

Skirting between thunder storms VFR does not make for a relaxing flight.

HiTech

[bustr]

1966 Cessna 150D square fin, Ft. Worth to Kelly AFB.

 I had the opportunity to watch lightning cross between thunder heads while we were threading openings between thunder heads to get back to Kelly. Looks like something out of a science fiction movie when the lightning discharges across clouds. We stayed away from those looking for bigger openings. There were other places that the sun shined down through low light showers from behind the clouds making rainbows near the ground.

Later that year the same opportunity to look at thunder heads and shower rainbows in a restored Bobcat as a passanger and again rear seat in a T34 avoiding thunder heads. Texas always impressed me as a place wit alot of tall clouds. 63 I saw Peshawar from the air in a Taylorcraft Austor (J/5 Aiglet) when the first monsoon fronts leading with lightning strikes were arriving out of Inda. Then it rained and thundered almost nonstop for 2 weeks and turned that part of Pakistan into a mud pit.

[Babalonian]

Donner pass was fun riding through on the way to land this weekend, had a good headache the next day.      Didn't help the sky was making baby Theads above.

[Babalonian]

Decent to land at TRK begins around minute 5.
http://youtu.be/T3jmEWZWSjs

.

[Midway]

Decent to land at TRK begins around minute 5.
http://youtu.be/T3jmEWZWSjs

Will probably still take 20 minutes for youtube to finish uploading/processing and for it to be ready to view.

   You're a real pilot too, huh?

[Babalonian]

  You're a real pilot too, huh?

I help fix them, not break them.  (not yet, maybe soon, going back to school for A&P first, and even then its a long way to the front seat of this bird.)








(^ two bonified Tuskegee Airmen for Friday dinner)

[Midway]

I help fix them, not break them.  (not yet, maybe soon, going back to school for A&P first, and even then its a long way to the front seat of this bird.)

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(^ two bonified Tuskegee Airmen for Friday dinner)

Awesome.