Greg of Auto and Airplanes has asked for a Debate

[Shortround6]

I have a little experience with this doing annual pump tests.

Now at sea level the air pressure on the surface of the water is 14.7lb/sq in. and if you had 100% vacuum in the semi rigid tube you should be able to suck the water up over 20ft. If I remember right theory says you can get 2 ft per pound of air pressure.
Ok I looked it up.

But you can't reach 100% vacuum outside of a well equipped lab. The problem as you go higher (Like Bolivia) you have less air pressure pushing down on the water which means less pressure to force it up the tube but the weight is pretty much the same (no super lab equipment to measure gravity) so you can lift it less.
Didn't matter if we used a 12hp salvage pump or 300hp/1500gpm diesel pumper. We could only pull water up to the same height.

We weren't dealing with gasoline vapor or other problems.
You can not suck harder than 100% vacuum.
Maybe you can get 80-90%, our gauges didn't measure vacuum very well.
If, on the other hand, your water (liquid) was in a sealed box/tank and you could add even a few pound of pressure to box/tank you could raise the lift distance of the pump.

gasoline is lighter than water, but as stated by others, the pressure inside the tanks is affected by other things. (below zero temperature are not going to help).

You don't need much pressure in the tank, you just need enough to help lift the fluid to the pump. even a couple of pounds of pressure can lift the fluid (fuel) 3-4 ft and then the pump will take care of the rest.

Fire pumps that were 15 to 20 years old that had good gaskets and seals (and grease to seal off the leaks) could pull their rated flow at the specified engine rpm unless they had sucked up a lot of sand, rocks, debris. Fish didn't bother them

Hope I have not confused you more.

 

[Thumpalumpacus]

I have a little experience with this doing annual pump tests.
View attachment 783052
Now at sea level the air pressure on the surface of the water is 14.7lb/sq in. and if you had 100% vacuum in the semi rigid tube you should be able to suck the water up over 20ft. If I remember right theory says you can get 2 ft per pound of air pressure.
Ok I looked it up.
View attachment 783051
But you can't reach 100% vacuum outside of a well equipped lab. The problem as you go higher (Like Bolivia) you have less air pressure pushing down on the water which means less pressure to force it up the tube but the weight is pretty much the same (no super lab equipment to measure gravity) so you can lift it less.
Didn't matter if we used a 12hp salvage pump or 300hp/1500gpm diesel pumper. We could only pull water up to the same height.

We weren't dealing with gasoline vapor or other problems.
You can not suck harder than 100% vacuum.
Maybe you can get 80-90%, our gauges didn't measure vacuum very well.
If, on the other hand, your water (liquid) was in a sealed box/tank and you could add even a few pound of pressure to box/tank you could raise the lift distance of the pump.

gasoline is lighter than water, but as stated by others, the pressure inside the tanks is affected by other things. (below zero temperature are not going to help).

You don't need much pressure in the tank, you just need enough to help lift the fluid to the pump. even a couple of pounds of pressure can lift the fluid (fuel) 3-4 ft and then the pump will take care of the rest.

Fire pumps that were 15 to 20 years old that had good gaskets and seals (and grease to seal off the leaks) could pull their rated flow at the specified engine rpm unless they had sucked up a lot of sand, rocks, debris. Fish didn't bother them

Hope I have not confused you more.

Thank you. I was struggling to explain this in terms of a pumper drafting from a water source but couldn't get the words right. At a certain point, a suction pump will not drag the fluid up any more. You'll cavitate and burn out your bearings. That's why we liked our two-stagers -- first stage low to get the wet stuff up, second stage to get the output to good pressure.

The other thing is that the fuel is not "boiling off" at the low temps at 25,000'. It vaporizes as it warms up, not as it cools down, which I know you know and am only saying for the readers herein. As it cools down, it vaporizes less and not more.

 

[Low Battery]

I have a little experience with this doing annual pump tests.
View attachment 783052
Now at sea level the air pressure on the surface of the water is 14.7lb/sq in. and if you had 100% vacuum in the semi rigid tube you should be able to suck the water up over 20ft. If I remember right theory says you can get 2 ft per pound of air pressure.
Ok I looked it up.
View attachment 783051
But you can't reach 100% vacuum outside of a well equipped lab. The problem as you go higher (Like Bolivia) you have less air pressure pushing down on the water which means less pressure to force it up the tube but the weight is pretty much the same (no super lab equipment to measure gravity) so you can lift it less.
Didn't matter if we used a 12hp salvage pump or 300hp/1500gpm diesel pumper. We could only pull water up to the same height.

We weren't dealing with gasoline vapor or other problems.
You can not suck harder than 100% vacuum.
Maybe you can get 80-90%, our gauges didn't measure vacuum very well.
If, on the other hand, your water (liquid) was in a sealed box/tank and you could add even a few pound of pressure to box/tank you could raise the lift distance of the pump.

gasoline is lighter than water, but as stated by others, the pressure inside the tanks is affected by other things. (below zero temperature are not going to help).

You don't need much pressure in the tank, you just need enough to help lift the fluid to the pump. even a couple of pounds of pressure can lift the fluid (fuel) 3-4 ft and then the pump will take care of the rest.

Fire pumps that were 15 to 20 years old that had good gaskets and seals (and grease to seal off the leaks) could pull their rated flow at the specified engine rpm unless they had sucked up a lot of sand, rocks, debris. Fish didn't bother them

Hope I have not confused you more.

So If I am understanding this correctly, it doesnt matter how powerful the pump is because you are ultimately limited by the fact that regardless of how good your pump is you cant pull harder than the ambient pressure because it cant equalize any better than it is being pushed by the atmosphere. No pump, however powerful, can exceed vacuum and even then you cant pull harder than the other side is pushing. So the only solution is to pressurize the side you are drawing from so that you have more pressure on that side.

so if I have that right, what is that document on about with 16lbs of pressure?

 

[wuzak]

The thing is that by 1944 losses in 8th AF had largely shifted from losses to fighters to losses from flak.

I'm willing to bet that USAAF fighters over Schweinfurt for that raid would've reduced B-17 losses. How much is obvs uncertain, but the inbound track would likely have suffered less.

By mid to late 1944 the bulk of the losses were to flak.

In the first few months of 1944 the Eight AF was still losing large numbers of bombers per mission.

I'm not sure that the presence of P-47s over Schweinfurt would have saved many, if any, B-17 crews.

German losses, however, would have been higher.

 

[drgondog]

I don't think the document listing the 1942 200 gallon tank shows anything really. We have bo idea what that tank is or it's specifications. It could be a ferry tank that was made of metal. Or otherwise unpressurized.

Could it not also just be the 205 gallon tanks of the later war but still in development?

The assertion that there was some high altitude capable 200 gallon tank before now never discovered by historians remains without evidence.

I suspect without proof that the noted 200gal steel tank experienced initial problems - either with Republic mounting scheme or sway braces contemplated with future B-7/B-10 rack scheme. Recall that would begreater weight than 1000 ound bomb. I also suspect that it was downscaled to the 150gal flat tank - which was delivered first.

Strictly opinion.

 

[drgondog]

By mid to late 1944 the bulk of the losses were to flak.

In the first few months of 1944 the Eight AF was still losing large numbers of bombers per mission.

I'm not sure that the presence of P-47s over Schweinfurt would have saved many, if any, B-17 crews.

German losses, however, would have been higher.

The bomber losses to flak were in the 1% range. Fighters far greater threat until 1945. chwinfurt losses were GAF inflicted.

IMPO the availability of several groups in relay escort, with target escort - would have reduced the losses significantly. IIRC 80% of victory credits awarded were to 109s. 12% to FW 190s and rest to t/e.

 

[Shortround6]

So If I am understanding this correctly, it doesnt matter how powerful the pump is because you are ultimately limited by the fact that regardless of how good your pump is you cant pull harder than the ambient pressure because it cant equalize any better than it is being pushed by the atmosphere. No pump, however powerful, can exceed vacuum and even then you cant pull harder than the other side is pushing. So the only solution is to pressurize the side you are drawing from so that you have more pressure on that side.

so if I have that right, what is that document on about with 16lbs of pressure?

That is pretty close or it is expressed a different way.
The fuselage or engine pump is usually feed by gravity.
When we are comparing theory to reality things get complicated. If you are trying to suck water up 15ft or more with a fire truck (1/2 of what theory says) you have to go around to EVERY cap/outlet with a spanner and rubber mallet to make sure there are no leaks. Air tight is different than "resting" water tight. Air doesn't have surface tension. If i Run the pump at 200psi what I thought was water tight looks like an irrigation device

Air pressures in inches Hg
sea level.................29.92
11,000ft..................19.79
13,000ft..................18.29
18,000ft..................14.94
19,000ft..................14.33
27,000ft..................10.16

Once you have established flow (you are sucking water or fuel) everything is good, you are unlikely to loose it (even syphoning water through a hose over a barrier) unless
you introduce a bubble (air or fuel vapor or?), the bubble will not transmit the force needed to the feed side of the pipe. If you stop flowing, like turn selector valve to different tank then trouble can really start.

Now from the very abbreviated table on air pressure we can see we have about 2/3rds the lifting power at 11,000ft than we do at sea level and at 18,000ft we have about 1/2.
At 27,000ft we have just over 1/3 of the lifting power.
Now if 18.29 in (pressure at 13,000ft) makes everything work right, I only need, at 27,000ft, to add 8.13 in of pressure to the tank, Which is just over 4psi. doesn't sound like much but

75 gal and 108 gal drop tanks. That is a lot of square inches.

 

[Engineman]

I think we have all covered the realities of AvGas vapour pressure, pump uplift limitations and the advantages of air pressurised tank feed in some detail.
Great to read all the info posts on here!

Eng

 

[Geoffrey Sinclair]

8th AF Heavy Bomber losses on combat sorties by cause by month, percentage lost to fighter, flak, 5,690 losses total, known to be missing some B-24 write offs at least and includes some Mediterranean operations losses, the USAAF Statistical Digest has 5,548 losses, the 8th Air Force Report has 5,858 losses.

There are the usual value judgements, for example if a bomber is shot down and hits and destroys another bomber while crashing, is that a collision? The losses on the ground are mainly in Russia and France/Belgium (1 January 1945). Friendly fire is mostly friendly bombs

Month

Aphrodite

Battle

Collision

Crash

Flak &

Fighter

Flak

Friendly

Fuel

Icing

Landing

Mechanical

On

Take off

Taxi

Not

Total

Credit

%fighter

%flak

Month

Aphrodite

Damage

Collision

Crash

Fighter

Fighter

Flak

Fire

Starvation

Icing

Accident

Failure

Ground

Accident

Accident

given

Total

Sorties

%fighter

%flak

Sep-42​

1​

2​

3​

106​

1.89​

0.00​

Oct-42​

1​

1​

1​

6​

1​

10​

157​

3.82​

0.64​

Nov-42​

1​

2​

1​

4​

5​

1​

14​

382​

1.05​

1.31​

Dec-42​

1​

14​

15​

243​

5.76​

0.00​

Jan-43​

2​

1​

2​

10​

5​

1​

3​

24​

279​

3.58​

1.79​

Feb-43​

2​

4​

13​

5​

24​

298​

4.36​

1.68​

Mar-43​

2​

1​

2​

15​

2​

22​

716​

2.09​

0.28​

Apr-43​

3​

21​

4​

28​

373​

5.63​

1.07​

May-43​

3​

9​

39​

20​

1​

1​

73​

1340​

2.91​

1.49​

Jun-43​

5​

2​

7​

60​

15​

1​

90​

1447​

4.15​

1.04​

Jul-43​

13​

4​

10​

67​

36​

1​

3​

1​

2​

137​

2334​

2.87​

1.54​

Aug-43​

7​

6​

15​

79​

41​

3​

4​

1​

1​

157​

2058​

3.84​

1.99​

Sep-43​

1​

6​

3​

3​

38​

21​

24​

1​

3​

100​

2561​

1.48​

0.82​

Oct-43​

12​

1​

13​

141​

35​

2​

5​

7​

216​

2159​

6.53​

1.62​

Nov-43​

2​

11​

2​

11​

53​

16​

1​

13​

1​

110​

2916​

1.82​

0.55​

Dec-43​

9​

8​

2​

21​

80​

49​

3​

16​

4​

6​

2​

200​

5618​

1.42​

0.87​

Jan-44​

4​

12​

6​

12​

127​

36​

1​

1​

8​

7​

214​

5562​

2.28​

0.65​

Feb-44​

12​

8​

8​

26​

147​

74​

5​

1​

3​

16​

2​

302​

8572​

1.71​

0.86​

Mar-44​

12​

19​

6​

12​

157​

112​

4​

1​

3​

21​

5​

1​

353​

10552​

1.49​

1.06​

Apr-44​

13​

2​

7​

13​

203​

140​

4​

3​

6​

21​

4​

1​

417​

11428​

1.78​

1.23​

May-44​

13​

21​

4​

9​

160​

115​

6​

4​

13​

18​

1​

9​

1​

374​

16346​

0.98​

0.70​

Jun-44​

7​

10​

11​

12​

42​

181​

1​

4​

6​

21​

44​

3​

6​

2​

350​

25866​

0.16​

0.70​

Jul-44​

17​

22​

10​

7​

60​

151​

1​

10​

18​

17​

3​

2​

5​

323​

21979​

0.27​

0.69​

Aug-44​

6​

29​

12​

6​

5​

36​

172​

1​

1​

10​

13​

5​

2​

3​

301​

21837​

0.16​

0.79​

Sep-44​

3​

27​

22​

5​

5​

97​

141​

2​

7​

11​

3​

4​

2​

329​

16556​

0.59​

0.85​

Oct-44​

4​

12​

17​

3​

27​

95​

1​

5​

14​

3​

2​

183​

17717​

0.15​

0.54​

Nov-44​

25​

14​

5​

2​

56​

130​

1​

4​

8​

4​

3​

1​

253​

15361​

0.36​

0.85​

Dec-44​

2​

28​

11​

8​

3​

41​

61​

1​

1​

14​

11​

12​

2​

195​

16260​

0.25​

0.38​

Jan-45​

2​

55​

19​

6​

2​

13​

102​

1​

8​

13​

20​

11​

16​

1​

269​

15249​

0.09​

0.67​

Feb-45​

38​

14​

8​

1​

6​

82​

2​

8​

6​

28​

7​

1​

201​

20194​

0.03​

0.41​

Mar-45​

30​

24​

9​

1​

37​

98​

4​

3​

6​

16​

1​

3​

232​

28826​

0.13​

0.34​

Apr-45​

13​

16​

7​

2​

42​

57​

10​

4​

7​

1​

7​

4​

170​

18459​

0.23​

0.31​

May-45​

1​

1​

78​

0.00​

1.28​

Total

17​

390​

289​

119​

215​

1893​

2003​

44​

100​

1​

130​

287​

57​

96​

34​

15​

5690​

293829​

0.64​

0.68​

% of loss

0.30​

6.85​

5.08​

2.09​

3.78​

33.27​

35.20​

0.77​

1.76​

0.02​

2.28​

5.04​

1.00​

1.69​

0.60​

0.26​

 

[Reluctant Poster]

The daylight raids were not 'suspended' by LW as much as bad weather over the continent, but Bremen and Kiel remained as tagets (some successfully escorted by 55th FG P-38s, but no P-47s)

I've always found that hard to believe that bad weather was continuous for 3 months! Further more it only affected areas of Germany outside of the combat radius of 8th​ AF fighters.
One month after Black Thursday RAF Bomber Command relaunched their Battle of Berlin. In two months of inaction by the 8th​ AF they flew 10 missions to Berlin totaling ~ 5000 heavy bomber sorties. In addition they flew deep missions to other targets in Germany. In his book "The Berlin Raids" Martin Middlebrook notes that there was a 12 day period early in December when no heavy bombers flew but otherwise Bomber Command was flying on a regular basis deep into Germany. Either the weather cleared up at night or there was significant difference between the RAF and the USAAF definitions of bad weather.
The 8AF did fly a lot of missions to Germany during this period but without penetrating beyond fighter range.

 

[tyrodtom]

The RAF flew in a stream, aircraft sent out at intervals to find their way to whatever targets they were assigned.
The possibility of aircraft colliding in bad weather not impossible, but remote.

The 8th AF had to assemble complex formations of hundreds of aircraft over southern England, and maintain that formation over Europe to the target.
I think you can see the much greater possibility of collisions, or the aircraft losing any resemblance of a formation in bad weather.

 

[drgondog]

I've always found that hard to believe that bad weather was continuous for 3 months! Further more it only affected areas of Germany outside of the combat radius of 8th​ AF fighters.
One month after Black Thursday RAF Bomber Command relaunched their Battle of Berlin. In two months of inaction by the 8th​ AF they flew 10 missions to Berlin totaling ~ 5000 heavy bomber sorties. In addition they flew deep missions to other targets in Germany. In his book "The Berlin Raids" Martin Middlebrook notes that there was a 12 day period early in December when no heavy bombers flew but otherwise Bomber Command was flying on a regular basis deep into Germany. Either the weather cleared up at night or there was significant difference between the RAF and the USAAF definitions of bad weather.
The 8AF did fly a lot of missions to Germany during this period but without penetrating beyond fighter range.
View attachment 783234

6/10 and above made accurate daylight bombing 'iffy' Europe in Fall/Winter has a lot of cloud cover.

 

[33k in the air]

Either the weather cleared up at night or there was significant difference between the RAF and the USAAF definitions of bad weather.

You've missed a possibility: Bomber Command had been steadily increasing its ability to fly in poor weather.

Bad weather was a double-edged sword. It helped as German night-fighters were sometimes grounded by bad weather even though the bombers were flying, and made it harder to find and intercept the incoming attackers. It hindered by making it more difficult to navigate to and mark the target. Flying in bad weather was much more challenging and raised the risk of accidents. Icing was a significant concern in winter months.

 

[DarrenW]

I happened to run across this little nugget of information last night. It's from the website 90th Bomb Group Main Menu
I've provided an excerpt describing the standard mission profile for B-24s of the 90th BG stationed in New Guinea during 1943. It supports the belief that USAAF heavy bombers operated over New Guinea at a much lower altitudes than was common in the ETO :

...The standard procedure was to climb to 18,000 feet to clear the Owen Stanley Mountains in
central New Guinea with peaks over 13,000 feet high. The crews breathed oxygen through their
masks and wore heavy clothes against the cold temperatures at altitude even though they were
flying above very hot and humid equatorial temperatures at the surface. The squadrons would
fly north beyond the New Guinea north coast and turn south for the bomb runs to approach from
the sea at about 10,000 feet. There were always heavy anti-aircraft ground fire (flak) and a
swarm of fighters to defend against.

The article also states that on this particular mission the escorting fighters where not flying close enough to the bomber formation to aid in their defense:

...The Japanese were ready. Anti-aircraft fire over the target was heavy, intense, accurate and
deadly. Somehow, the P-47 fighter escort was too high, and as the bombers began their run-in to
the target, the main body of the group was strung out due to weather. A swarm of Japanese
fighter aircraft had been scrambled in time to intercept the American intruders.

https://www.90thbombgroup.org/Narrative%20of%20Wewak%20Mission%20%201%20Dec%201943.pdf

 

[MiTasol]

People forget that the high humidity in the tropics means icing is/was a continuous issue. One Nomad crash in PNG in the 80s was caused by intake icing on take off at 8,500 feet.

 

[pbehn]

People forget that the high humidity in the tropics means icing is/was a continuous issue. One Nomad crash in PNG in the 80s was caused by intake icing on take off at 8,500 feet.

With conspiracy theories anything unsupportive is forgotten instantly, anything that may distract is used endlessly to go down cul de sacs and meanders. So far as I understand it, the 1943 P-47 with 305 gals internal fuel could not fight for 20 minutes over Schweinfurt and make it back to UK. Even with a 200 gallon tank it couldnt do it, but it was closer to doing it than with no external tank or with 100 gallon droppable tank. It is BS that only results in more conspiracy videos not a correction to the original nonsense. I regularly used to drive from Northern England to Northern Germany, I couldnt treat the fact that my car cannot travel on water as an esoteric irrelevance. The straight line distance between some airfield and Schweinfurt at optimal consumption conditions means less than nothing.

 

[tyrodtom]

I've noticed a lot of videos on U-Tube are so badly researched it's almost like they deliberately make bad videos so people will watch them just to spot the errors.
People make money with these videos based on the number of views, evidently, the number of up thumbs, or down thumbs, doesn't seem to matter.

I seen some videos brain numbing bad, sometimes outright lies, but viewers still give them a thumbs up.

Greg is only looking out for his billfold, truth has a low priority on his site.
Now days conspiracy theories sell.

 

[wuzak]

Finally watching his video "P-47 Pacific Theater Missions".

One of his examples is from Februry 1944, and he isn't sure whether the aircraft was configured with the "Brisbane" tank built in Geelong by Ford, or later standard tanks.

He also cites the small amount of performance lost by the P-47 when carrying drop tanks, and concluded that the tanks don't add much drag.

He didn't seem to make the connection that the P-47 could also be draggy, and that the extra drag of the tanks was proptionally smaller than for other aircraft.

 

[Geoffrey Sinclair]

Trying to remember a report from years ago about how cloud cover on average peaks about the middle of the day and has a minimum at night. As far as aircraft are concerned the tighter the formations the better the weather needs to be. Cloud also decreases with altitude, as a result the 8th Air Force reports 7.3% of B-17 sorties sent were weather aborts, for the B-24 it was 11.1%, for the 15th Air Force it was 12.8 and 14.8%, but remembering the weather abort rate is also influenced by when the individual units received usually H2X equipped pathfinders, it took until the second half of 1944 for all 8th Air Force bomber units to have their own.

8th Air Force June 1943 to April 1945 target area cloud cover forecast versus actual, less than 5/10 cloud classified as visual, 5 to 8/10 classified as visual assist, 8 to 10/10 classified as blind bombing.

Forecast	Actual
Forecast	less than 5/10	5 to 8/10	8 to 10/10	Total
less than 5/10	155​	42​	39​	236​
5 to 8/10	31​	68​	83​	182​
8 to 10/10	9​	16​	81​	106​
Total	195​	126​	203​	524​

The forecast was accurate 58%, worse 31% and better 11% of the time.

The 14/15 February raids on Dresden, another night bomber force went to Bohlen, 60 miles from Dresden, encountering thick icing cloud, the raid was considered so poor no post strike reconnaissance was done and a repeat raid carried out on the 19th.

The USSBS weather report rule of thumb is in winter the night heavy bombers had over 2.5 times the chance of visual bombing at Munich than the day ones, in summer it was the day heavy bombers had 1.5 times the chance of night ones. Altitude also matters, the 9th AF mediums by day had 1.8 times the chance of the USAAF heavies in winter and 1.5 in summer. At night the higher flying Mosquitoes always had less chance than the heavies. Over a year the ratio numbers for visual attacks were Mosquito 15.8, night heavy 18.7, day medium 19.5, day heavy 11.2. If the night heavy bombers were largely denied moonlight nights their ratio figure drops to 11.3. Bomb time 1300 by day, 20-25,000 feet for heavies, 10-15,000 feet for mediums, night attack 0100 hours 15-20,000 feet for heavies, 25-30,000 feet for Mosquito.

Bomber Command main force bombed Leipzig 3/4 December 1943, next raid on a German target was Berlin on 16/17 December. Apart from any weather issues the full moon was on 11 December. On 3 December the moon set at 22:27 GMT at London, on 16 December the moon rose at 20:40, setting at 11.38 on the 17th. Mosquito raids were run on the 4th, 10th, 11th, 12th, 13th and 15th.

The 8th Air Force started doing non visual bombing in September 1943 then to end April 1944 the %of visual bombing by month attacking Germany was
47.11, 72.05, 27.56, 30.41, 24.78, 54.14, 33.61, 77.34,
non German targets visual bombing percentage for the same period was
99.30, 100.00, 100.00, 100.00, 100.00, 79.87, 89.61, 95.30 (The September 1943 non visual bombs were dropped during night raids)

By tonnage 67.88% of bombs dropped September 1943 to April 1944 inclusive were on Germany, by month it was
1,091.5, 4,184.9, 5,383.5, 8,893.7, 8,287.8, 13,065.8, 14,641.0, 15,274.7

looking at the tonnages dropped on Germany visually,
514.2, 3015.2, 1,483.8, 2,705.0, 2,053.4, 7,073.8, 4,920.3, 11,813.8

After October 1943 it took until February 1944 for more bombs to be dropped on Germany visually in a given month, which is a contributor to the way losses as a percentage of sorties dropped.

 

[pbehn]

Finally watching his video "P-47 Pacific Theater Missions".

One of his examples is from Februry 1944, and he isn't sure whether the aircraft was configured with the "Brisbane" tank built in Geelong by Ford, or later standard tanks.

He also cites the small amount of performance lost by the P-47 when carrying drop tanks, and concluded that the tanks don't add much drag.

He didn't seem to make the connection that the P-47 could also be draggy, and that the extra drag of the tanks was proptionally smaller than for other aircraft.

That is perfectly correct, small is a great word, on a gas guzzling hog like a P-47 a 200 gallon tank only produces a "small" increase in range, I have no idea why Greg bangs on about it so much. To match the P-38 and P-51 the P-47 needed around 500 gallons internal and 400 gallons external fuel, since that was impossible, lets talk about pressurisation of fuel in modern airliners.