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B-17 & B-24 - 9/23/2012 1:14:44 AM

treespider

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Just a thought stream as I work on mod... was researching ranges of the B-17 & B-24 and found this.

Stock has the following ranges:
B-17D - 2510nm
B-17E - 2440nm
B-17F - 2130nm
B-17G - 2230nm

LB-30 - 2960nm
B-24D - 2590nm
B-24D1 - 2440nm
B-24J - 2440nm

The Stock values are consistent with anecdotal evidence that states that the B-24 replaced the B-17 in the Pacific due to its longer range.

However in working on my mod I found some interesting values from other sources:

When I looked at the data in "American Fleets" (Admiralty Trilogy), Clash of Arms Games by Larry Bond et al. I found the following values:

B-17D - 2320nm
B-17E - 2871nm
B-17F - 3671nm
B-17G - 3671nm + 870nm(aux bay tank) = 4541nm

LB-30 - 2200nm + 486nm(aux bay tank)= 2686nm
B-24D - 1850nm + 530nm(aux bay tank)= 2380nm
B-24D1 - 1850nm + 530nm(aux bay tank)= 2380nm
B-24J - 1800nm + 530nm(aux bay tank)= 2330nm

Squadron Signals "B-17 in Action" and "B-24 in Action" had the following data:
B-17D -
B-17E - 2870nm
B-17F - 3845nm
B-17G - 3260nm

LB-30 -
B-24D - 2480nm
B-24D1 - 2480nm
B-24J - 1827nm

Profile Publication #77 for the B-17E & F places ranges as
B-17E - 2870nm
B-17F - 3845nm

Aircraft Profile #205 for the B-17G places the range as
B-17G - c.2960nm

The B-17C Pilots Flight Manual lists maximum range as:
B-17C - c.2975nm - value taken Range Chart (p.65)

The B-17F Pilots Flight Manual lists maximum range as:
B-17F - c.3845nm - value take from Ferry Range Chart (p.104)

The B-17G Pilots Flight Manual Lists Maximum range as:
B-17G - c.3280nm value taken from Range Chart (p.95)

Now the Flight manuals do indicate shorter MAX ranges for the B-17 when carrying a typical bombload of 5-6000lb with a GROSS Total TakeOff Weight of c.57,000lbs (for F&G)-
B-17C = 2088nm
B-17F = 2150nm
B-17G = c.2700nm

All of those sources seem to indicate a longer ferry range for the B-17 than the B-24, although I have yet to look at B-24 Flight manuals. They also suggest that the "American fleets" values are perhaps more accurate for the B-17 series than the Stock values in terms of the transfer ranges.

Discussion?

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RE: B-17 & B-24 - 9/23/2012 1:25:40 AM

witpqs

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The problem is that without knowing their actual sources for that information, it is impossible to know 1) the context of the source, and 2) to form a judgement about the reliability of the source's information.

I've only ever heard that the B-24 had longer range with a heavier payload than the B17. And that the B-17 was tougher than the B-24. I am not a source, I can't give you primary sources. But the old saying about extraordinary claims requiring extraordinary evidence - well, I would keep a healthy skepticism until you see what's at the bottom of the pile.

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RE: B-17 & B-24 - 9/23/2012 1:56:18 AM

treespider

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quote:

ORIGINAL: witpqs

The problem is that without knowing their actual sources for that information, it is impossible to know 1) the context of the source, and 2) to form a judgement about the reliability of the source's information.

I've only ever heard that the B-24 had longer range with a heavier payload than the B17. And that the B-17 was tougher than the B-24. I am not a source, I can't give you primary sources. But the old saying about extraordinary claims requiring extraordinary evidence - well, I would keep a healthy skepticism until you see what's at the bottom of the pile.

The flight manuals are direct from the manufacturer. I found a number online on Scribd such as:

HANDBOOK of OPERATION AND FLIGHT INSTRUCTIONS for the MODEL B-17C BOMBARDMENT AIRPLANE manufactured by BOEING AIRCRAFT COMPANY

I would consider the flight manuals from the manufacturer as primary sources.

The Profile Publications and Squadron Signal I would consider secondary. "American Fleets" I would consider a summary of Primary and Secondary source data. They do provide an extensive bibliography for their data.

Interestingly "Fortress Against the Sun" pp.207-208 recounts a mission flown by five B-17s from the 28th & 93rd BS on June 30, 1942. The mission was considered the longest combat mission with return to the same base flown by the 19th BG. The B-17s depart Darwin, bomb Kendari, proceed to Dili, bomb Dili, and return to Darwin covering 3560 miles (c.3097nm).

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RE: B-17 & B-24 - 9/23/2012 3:08:41 AM

witpqs

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How about bomb load, though? That's a huge factor as it can't auto-adjust on a sliding scale in AE (AFAIK). That might have been a mission with a very small ordnance load.

Or... armor might have been removed for some missions. Or different for the figures cited by some sources. The same for armament, and ammo for those .50 cals. or maybe a dozen other differences.

Sorry all I have is perspective on the questions to resolve, but no data for you.

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RE: B-17 & B-24 - 9/23/2012 4:21:32 AM

treespider

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quote:

ORIGINAL: witpqs

How about bomb load, though? That's a huge factor as it can't auto-adjust on a sliding scale in AE (AFAIK). That might have been a mission with a very small ordnance load.

Or... armor might have been removed for some missions. Or different for the figures cited by some sources. The same for armament, and ammo for those .50 cals. or maybe a dozen other differences.

Sorry all I have is perspective on the questions to resolve, but no data for you.

I realize that is just one anecdote from FatS which indicates the mission covered 3560 miles. I'm sure the mission extended into bingo fuel.

However - I can take the B-17G Pilot's Flight Manual and work backwards...by the way it likely wasn't possible to fly this mission with a B-17G.

B-17G Flight Manual

p.80 Sample Loading chart indicates with full up tanks including bomb bay tanks the B-17G has 3600 gal of fuel. 400 are held in reserve allowing 3200gal for the mission. The B-17 can still load 7500 lbs of bombs before reaching max load of 70,000lbs.

However we're only going to load an extended range load of 2000lbs = 4x500lbs. Which puts our take off weight at 64,500lbs (heavy). Average was 50-60,000lb.

Figure 76 of the manual "Flight Operations Chart" refers us to Fig 90 & Fig 91 for Max Range column V.

Referring to Figure 90 at Heavy Weight 60,000+ lbs the B-17 can fly at Condition U.

Referring to Figure 91 with 3200 gallons of Fuel, Condition U provides a Max Range of 2760 miles (2400nm)...

So our Pilot Manual B-17G carrying 4x500lb bombs can cover 2400 nm. Nearly twice the Stock extended range of 1310nm.

< Message edited by treespider -- 9/23/2012 4:25:59 AM >

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RE: B-17 & B-24 - 9/23/2012 4:45:52 AM

witpqs

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Ostensibly one of the reasons that B-24s went against Polesti was their longer range compared to the B-17. Realizing that anything might not be true, but taking that and the data from the B-17 manual to be true, there must be other factors.

One that comes to mind (and often mentioned in AE) is time to marshal the group into formation once in the air. But that won't account for such a discrepancy.

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RE: B-17 & B-24 - 9/23/2012 12:40:25 PM

Dili

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That is how it should be verified treespider

All range values around are of no value if they don't tell what fuel level and weapon load.

When i searched the bombers range for a supposed to be War in Mediterranean i dismissed all Francillon and alikes went directly to official manuals, and after manuals that don't tell whole story the typical operation/range load outs. In some cases that i have found strange i even checked specific fuel consumptions to verify specially between different planes that used the same engine.

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RE: B-17 & B-24 - 9/23/2012 12:44:42 PM

Dili

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quote:

Ostensibly one of the reasons that B-24s went against Polesti was their longer range compared to the B-17.

The B-24 that made Ploesti dropped a some weight to get more fuel. Some of the guns like in Doolitle raid were nothing more than wood poles. Even then some dropped/crashed because of higher consumption.

There is also another issue is that while in witp the aircraft go straight to the target in Ploesti there was a different route less dangerous to make instead of direct one.

< Message edited by Dili -- 9/23/2012 12:45:42 PM >

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RE: B-17 & B-24 - 9/23/2012 2:50:36 PM

PaxMondo

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quote:

ORIGINAL: treespider

quote:

ORIGINAL: witpqs

How about bomb load, though? That's a huge factor as it can't auto-adjust on a sliding scale in AE (AFAIK). That might have been a mission with a very small ordnance load.

Or... armor might have been removed for some missions. Or different for the figures cited by some sources. The same for armament, and ammo for those .50 cals. or maybe a dozen other differences.

Sorry all I have is perspective on the questions to resolve, but no data for you.

I realize that is just one anecdote from FatS which indicates the mission covered 3560 miles. I'm sure the mission extended into bingo fuel.

However - I can take the B-17G Pilot's Flight Manual and work backwards...by the way it likely wasn't possible to fly this mission with a B-17G.

B-17G Flight Manual

p.80 Sample Loading chart indicates with full up tanks including bomb bay tanks the B-17G has 3600 gal of fuel. 400 are held in reserve allowing 3200gal for the mission. The B-17 can still load 7500 lbs of bombs before reaching max load of 70,000lbs.

However we're only going to load an extended range load of 2000lbs = 4x500lbs. Which puts our take off weight at 64,500lbs (heavy). Average was 50-60,000lb.

Figure 76 of the manual "Flight Operations Chart" refers us to Fig 90 & Fig 91 for Max Range column V.

Referring to Figure 90 at Heavy Weight 60,000+ lbs the B-17 can fly at Condition U.

Referring to Figure 91 with 3200 gallons of Fuel, Condition U provides a Max Range of 2760 miles (2400nm)...

So our Pilot Manual B-17G carrying 4x500lb bombs can cover 2400 nm. Nearly twice the Stock extended range of 1310nm.

Not seeing reference to the 50 cal here... US manufacturer aircraft flight manuals were (are) generally written prior any armaments being loaded on board and also likely do not include the crew themselves. There are a lot of reasons for this, one of which is that the manufactorer cannot predict in theatre combat load outs.

I talked with Gene, ex B-24 belly gunner. He said that when the planes were ferried from stateside using the bonb bay tanks, there were no 50 cal guns in them yet. all the guns were added once they got to the theatre. ditto the crew. planes came over with just pilot+copilot. That is a LOT of weight being added.

He didn't recall ever using the bomb bay tanks in combat ... Gene flew out of africa and then italy ... not saying they weren't used, but his group never used them and so at least you have to put their combat use into the "Doolittle Raid" category which the devs have specificaly stated are not modelled.

Tree, i think you are looking for ghosts here. B17/B24 ranges are prolly two of the most important in game a/c ranges. I suspect that these were intensely scruntinized values by the devs .... I don't think you will be able to justify any changes to them ... Just my thoughts ...

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RE: B-17 & B-24 - 9/23/2012 3:40:30 PM

treespider

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From: Edgewater, MD
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quote:

ORIGINAL: PaxMondo

quote:

ORIGINAL: treespider

quote:

ORIGINAL: witpqs

How about bomb load, though? That's a huge factor as it can't auto-adjust on a sliding scale in AE (AFAIK). That might have been a mission with a very small ordnance load.

Or... armor might have been removed for some missions. Or different for the figures cited by some sources. The same for armament, and ammo for those .50 cals. or maybe a dozen other differences.

Sorry all I have is perspective on the questions to resolve, but no data for you.

I realize that is just one anecdote from FatS which indicates the mission covered 3560 miles. I'm sure the mission extended into bingo fuel.

However - I can take the B-17G Pilot's Flight Manual and work backwards...by the way it likely wasn't possible to fly this mission with a B-17G.

B-17G Flight Manual

p.80 Sample Loading chart indicates with full up tanks including bomb bay tanks the B-17G has 3600 gal of fuel. 400 are held in reserve allowing 3200gal for the mission. The B-17 can still load 7500 lbs of bombs before reaching max load of 70,000lbs.

However we're only going to load an extended range load of 2000lbs = 4x500lbs. Which puts our take off weight at 64,500lbs (heavy). Average was 50-60,000lb.

Figure 76 of the manual "Flight Operations Chart" refers us to Fig 90 & Fig 91 for Max Range column V.

Referring to Figure 90 at Heavy Weight 60,000+ lbs the B-17 can fly at Condition U.

Referring to Figure 91 with 3200 gallons of Fuel, Condition U provides a Max Range of 2760 miles (2400nm)...

So our Pilot Manual B-17G carrying 4x500lb bombs can cover 2400 nm. Nearly twice the Stock extended range of 1310nm.

Not seeing reference to the 50 cal here... US manufacturer aircraft flight manuals were (are) generally written prior any armaments being loaded on board and also likely do not include the crew themselves. There are a lot of reasons for this, one of which is that the manufactorer cannot predict in theatre combat load outs.

You should really check out the flight manuals. They do make allocations for crew weight, and .50 cals, and ammo, and oil...etc etc.

quote:

I talked with Gene, ex B-24 belly gunner. He said that when the planes were ferried from stateside using the bonb bay tanks, there were no 50 cal guns in them yet. all the guns were added once they got to the theatre. ditto the crew. planes came over with just pilot+copilot. That is a LOT of weight being added.

He didn't recall ever using the bomb bay tanks in combat ... Gene flew out of africa and then italy ... not saying they weren't used, but his group never used them and so at least you have to put their combat use into the "Doolittle Raid" category which the devs have specificaly stated are not modelled.

The Bomb Bay tanks were used in combat. Salecker mentions them several times In Fortress Against the Sun.

quote:

Tree, i think you are looking for ghosts here. B17/B24 ranges are prolly two of the most important in game a/c ranges. I suspect that these were intensely scruntinized values by the devs .... I don't think you will be able to justify any changes to them ... Just my thoughts ...

I was one of the Devs...I'm sure I could ask TimTom how he arrived at his ranges. And the last time I checked all of the devs were human.

In any event I plan on examining the B-24 manual today.

Attachment (1)

< Message edited by treespider -- 9/23/2012 3:45:46 PM >

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RE: B-17 & B-24 - 9/23/2012 4:11:15 PM

treespider

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Continuing my research I ran across this little tidbit in:

The Army Air Forces in World War II, Vol VI

Which tends to lend credence to what I'm finding in the flight manuals.

On pages 206-207

quote:

The B-17 and the B-24 inevitably invited comparison. Coming along four to five years after the B-17, the B-24 possessed an initial advantage. It carried a larger bomb load than the B-17 and could carry the load farther with a crew of the same size-ten men. Listed in the charts originally as having a range of 2,850 miles with a 2,500-pound bomb load, experience showed that it did have a longer reach than any other compering plane.53 It was this advantage that gave the

--207--

B-24 the call over the B-17 for service in CBI and SWPA, where Kenney's Fifth Air Force used it for the 2,400-mile round trip attacks on Balikpapan in 1944,* and where regularly, if less spectacularly, it extended the coverage of overwater search. Against the German Air Force, however, combat experience showed the plane to be lacking in armament and armor. Attempts to remedy these and other short-comings increased the weight of the plane and altered flight characteristics in such a way as to render it less stable. Lt. Gen. James H. Doolittle, commanding the Eighth Air Force, made his preference for the B-17 clear in a letter of January 1945.54 By that date the increased range of the B- 17 some time since had robbed the B-24 of its chief advantage.55 Against the Luftwaffe, the capital enemy, the rugged and steady B-17 remained the natural pick.

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"It is not the critic who counts, .... The credit belongs to the man who is actually in the arena..." T. Roosevelt, Paris, 1910

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RE: B-17 & B-24 - 9/23/2012 4:26:26 PM

witpqs

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quote:

ORIGINAL: treespider

Continuing my research I ran across this little tidbit in:

The Army Air Forces in World War II, Vol VI

Which tends to lend credence to what I'm finding in the flight manuals.

On pages 206-207

quote:

The B-17 and the B-24 inevitably invited comparison. Coming along four to five years after the B-17, the B-24 possessed an initial advantage. It carried a larger bomb load than the B-17 and could carry the load farther with a crew of the same size-ten men. Listed in the charts originally as having a range of 2,850 miles with a 2,500-pound bomb load, experience showed that it did have a longer reach than any other compering plane.53 It was this advantage that gave the

--207--

B-24 the call over the B-17 for service in CBI and SWPA, where Kenney's Fifth Air Force used it for the 2,400-mile round trip attacks on Balikpapan in 1944,* and where regularly, if less spectacularly, it extended the coverage of overwater search. Against the German Air Force, however, combat experience showed the plane to be lacking in armament and armor. Attempts to remedy these and other short-comings increased the weight of the plane and altered flight characteristics in such a way as to render it less stable. Lt. Gen. James H. Doolittle, commanding the Eighth Air Force, made his preference for the B-17 clear in a letter of January 1945.54 By that date the increased range of the B- 17 some time since had robbed the B-24 of its chief advantage.55 Against the Luftwaffe, the capital enemy, the rugged and steady B-17 remained the natural pick.

These are two interesting factoids about the B-24.

First off, they cite 2,850 mile range with 2,500lb bomb load. They don't specify round-trip or one-way.

Second, they cite "attacks", plural, of 2,400 miles round trip, but without citing bomb load.

2,400 miles round trip is 60 hexes round trip, 30 hexes one way. But they don't give the bomb load, nor note any special preparations such as reduced armor, guns, ammo, etc.

2,500lb bomb load is the extended range load out for B-24s in stock AE.

Even if you wind up with data for an adjustment of B-17/B-24 ranges, I am not seeing any doubling in the cards.

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RE: B-17 & B-24 - 9/23/2012 4:36:17 PM

treespider

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quote:

ORIGINAL: witpqs

Even if you wind up with data for an adjustment of B-17/B-24 ranges, I am not seeing any doubling in the cards.

I'm thinking the Stock B-24 ranges might be fairly accurate...my research is indicating the B-17 ranges are amiss.

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RE: B-17 & B-24 - 9/23/2012 4:49:43 PM

sandman455

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The B17 was a better high altitude aircraft. Doing a ferry mission then it makes sense that it might be able to best what the B24 could do by climbing high and staying there. Yet there is no question that the B24 was blessed with better range if the mission included a lower altitude requirement. Could be BS, but I think I read somewhere that down low a B24 on 3 engines could outrun a B17 on 4. This low altitude capability was what made it far more suitable for PTO operations.

The B24 also provided better flexibility within the bomb bay which is a significant factor. It would give mission planners more options that would undoubtably lead to more range capability for any particular target.

Aircraft have many mission variables that can influence the range by 5-10-15% or more. In short range aircraft this rarely nets you much. Yet as the range increases, these small percentages start to add up to lots of game hexes. As a game designer working within the constraints of a very abstract air model you really have no choice but to pick a rough and ready data point and stick with it. IMHO, giving the B24 more range than a B17 in the PTO is a pretty sound decision.

Of course its your mod so you should make it what you want.

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Post #: 14

RE: B-17 & B-24 - 9/23/2012 5:13:33 PM

treespider

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Two useful charts on the B-24.

1st The B-24D Range Chart...note Gross Weight includes 6man crew, 7x.50 cal, 471 rds per gun, standard armor plate.

Ranges are based on carrying the payload Full range...ie out and back. Formula is provided to account for dropping payload 1/2 the way out.

Attachment (1)

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RE: B-17 & B-24 - 9/23/2012 5:16:14 PM

treespider

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Now the second useful chart -

B-24D Gross Weight Nomogram

Used to calculate Gross Weight including fuel loads, bomb loads and armament load.

Attachment (1)

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RE: B-17 & B-24 - 9/23/2012 5:44:23 PM

PaxMondo

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quote:

ORIGINAL: treespider

I was one of the Devs...I'm sure I could ask TimTom how he arrived at his ranges. And the last time I checked all of the devs were human.

I know, and you might want to drop a note to TimTom about it. I think ammo wgt estimates will be challenging. 50 cal ammo is very heavy, even unbelted, and gunners always wanted to take max ... understandably so.

But, as noted above, your mod and you can do whatever you please. My mod is full of things that meet my requirements, but I have no intention of trying to explain to anyone else

< Message edited by PaxMondo -- 9/23/2012 6:35:04 PM >

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RE: B-17 & B-24 - 9/23/2012 5:46:27 PM

sandman455

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Pulling out flight manuals is not the way to go unless you have one for a D4Y or something. In which case you'd become everyone's hero by giving us some real data points.

You are playing a game that has an air model that doesn't take into account weather, winds, load variations (you get 2, or 3 if you count ferry), flight profiles, and the list goes on and on.

The flight manual was simply a tool. The range data in the back was a starting point for the crew. They would then factor in mission variables and these would be applied to the numbers.

While you can say these variables would effect both aircraft equally, it really wouldn't. The aircraft had different flight characteristics. As soon as you start using mission altitudes for what was necessary in the PTO, your B17 numbers would fall off considerably. You simply couldn't bomb anything of value in the Solomons at FL280. Also, navigating the South Pacific islands from 5 miles up was a no go as well.

Besides a military aircraft's flight manual is some of the best fiction reading I have ever done. If you feel so inclined to read further. . . some Sunday humor:

Sitting in a F18 dome I once tried to see how fast I could get the Hornet up to. It was sad. I had always been frustrated with the S3 simulator not being able to reach the max airspeed of the aircraft and now sitting in a F18 sim, I see the situation was much the same. As I spent the next 3min running the aircraft out of fuel, over the ICS came the tech who said she'll do a little more if you jettison the drop tank and put her in a shallow 0G dive. He was right, but I was still a ways from what was in the NATOPS appendix as she went dry.

As I climbed out, I bitched about how they could at least make our simulators do the numbers. He laughed and said that would hardly be simulating the real aircraft. Those numbers were for aircraft that didn't have racks, pylons or even matte grey paint. And of course he was right, the prototypes were set up for top speed runs and were far removed from any combat operations. He goes on to say that he feels my pain though, since he never got his pin. Most of the console techs were ex-military pilots. Having never heard of getting pins for top speed runs I had to ask:

"Pin?"

"Yeah M-D would give you a pin if you wrote in the maitnenance logbook for the aircraft that you took it up to Mach 2."

"M-D, McDonald Douglas - Phantoms?"

"Yup - most of us soon realized that some of the aircraft wouldn't do M2 even if you pointed them straight down and went for it."

We shared a laugh.

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Post #: 18

RE: B-17 & B-24 - 9/23/2012 6:27:16 PM

treespider

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quote:

ORIGINAL: sandman455

Pulling out flight manuals is not the way to go unless you have one for a D4Y or something. In which case you'd become everyone's hero by giving us some real data points.

The flight manuals at least give me a starting point and are likely the source of many of the figures cited in any number of summaries like Jane's or Hamlyn's Concise Guides or the Aviation Profile Series or the Crowood Books or the Squadron Signal series etc etc.

I stumbled across what I feel is a discrepancy in the B-17 because I started out by examining the numbers arrived at by Larry Bond et al which contradicted our game numbers for the B-17. I then checked out several different sources and came across the Flight Manuals....all of these sources point to a longer ranged B-17 than we see in game.

Yes I agree that nothing beats actually being able to gas the real thing up and taking it for a spin to see what it is capable of and recording the results ... for now I will content myself with hypothetical numbers comparisons since I doubt I will be able to take a B-24D out for a spin anytime in the near future.

One thing to keep in mind I can set six different data points for range - Normal, Extended, Max, DT Normal, DT Extended and DT Max. I can also set five different loads dependent on mission the Filter mechanism.

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Post #: 19

RE: B-17 & B-24 - 9/24/2012 1:23:59 PM

Dili

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quote:

Pulling out flight manuals is not the way to go unless you have one for a D4Y or something.

Pulling the manuals is the way to start and existing D4Y manual or not doesn't matter. Perfection can't be achieved.

Of course there is a big problem with game engine, a bomber or a fighter for that matter but the problem is more acute in bombers,. should only have the maximum range if it operates at its cruise altitude. One idea could be to use the maneuverability bands to affect the range.
The game also doesn't model well some benefits of low level flight, like being less easily detectable, bombers that drop out due to problems or excessive fuel consumption...

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Post #: 20

RE: B-17 & B-24 - 9/24/2012 6:06:26 PM

Gridley380

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I'll throw two more factors into the pot - formation flying penalties and course changes.

All manufacturer aircraft range data (I work for one) assumes the plane is flying alone and straight. A formation of heavies on a bombing run is obviously doing neither.

The 'lead' in a formation may burn fuel at the theoretical rate, but no one trying to hold station on them will unless they're Gods come down to Earth (of course, many pilots feel they themselves are, but...). Minor variations in wind, turbulence, etc. force you to constantly adjust your indicated airspeed, which wastes fuel. Not a lot - but on a thousand-mile run it will be noticeable.

Worse, however, not everyone can take off (or land) at once. Since the formation needs to arrive over target at the same time the first birds off the ground burn fuel while everyone else gets off the ground and climbs. The formation then needs to form up - more fuel lost, especially if you're coming from multiple bases. The USAAF in the ETO actually theater-modified veteran bombers with eye-catching full body paint jobs and load of flares just for this purpose - they'd take off, server as a reference point for a formation taking station, then land without flying the mission itself.

Course changes were mentioned above re: Ploesti - the game model assumes your A/C fly straight from their base to the target, attack, and fly straight back. Doglegs, often large ones, were common in flight plans to avoid expected fighters, flak, or weather. Each turn, for that matter, burns more fuel as planes jockey to keep relative station.

Probably more useful to look for detailed data on actual missions flown (with what bombload, aux tanks, armament, etc.), paying particular attention to ops losses.

While I'd love to see B-17 range go up, I have to ask if there are out-and-back missions that were historically flown with 'standard' loads and configurations that can't be flown in game? Flying FARP missions being beyond the game engine, sadly, means they don't count, along with any missions like the Doolittle raid where the A/C on the flight were modified.

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Post #: 21

RE: B-17 & B-24 - 9/24/2012 8:27:56 PM

Dili

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Yeah good points. Well anyone can put in game a small production batch of B-25 "Doolittle" and use it with House Rules. I think in game extreme ranges be it extended or normal should lead to more aborts, it is enough that wind is not favorable to change everything.
The fatigue for long range missons of several hours also should be more accute.

< Message edited by Dili -- 9/24/2012 8:32:17 PM >

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Post #: 22

RE: B-17 & B-24 - 9/25/2012 12:32:37 AM

treespider

Posts: 9796
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From: Edgewater, MD
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quote:

ORIGINAL: Gridley380

I'll throw two more factors into the pot - formation flying penalties and course changes.

All manufacturer aircraft range data (I work for one) assumes the plane is flying alone and straight. A formation of heavies on a bombing run is obviously doing neither.

The 'lead' in a formation may burn fuel at the theoretical rate, but no one trying to hold station on them will unless they're Gods come down to Earth (of course, many pilots feel they themselves are, but...). Minor variations in wind, turbulence, etc. force you to constantly adjust your indicated airspeed, which wastes fuel. Not a lot - but on a thousand-mile run it will be noticeable.

Worse, however, not everyone can take off (or land) at once. Since the formation needs to arrive over target at the same time the first birds off the ground burn fuel while everyone else gets off the ground and climbs. The formation then needs to form up - more fuel lost, especially if you're coming from multiple bases. The USAAF in the ETO actually theater-modified veteran bombers with eye-catching full body paint jobs and load of flares just for this purpose - they'd take off, server as a reference point for a formation taking station, then land without flying the mission itself.

Course changes were mentioned above re: Ploesti - the game model assumes your A/C fly straight from their base to the target, attack, and fly straight back. Doglegs, often large ones, were common in flight plans to avoid expected fighters, flak, or weather. Each turn, for that matter, burns more fuel as planes jockey to keep relative station.

Probably more useful to look for detailed data on actual missions flown (with what bombload, aux tanks, armament, etc.), paying particular attention to ops losses.

While I'd love to see B-17 range go up, I have to ask if there are out-and-back missions that were historically flown with 'standard' loads and configurations that can't be flown in game? Flying FARP missions being beyond the game engine, sadly, means they don't count, along with any missions like the Doolittle raid where the A/C on the flight were modified.

Those items are factored into the algorithm I am using to establish my Rng Normal and Rng Extended values. I'm using the flight manuals to establish the Baseline Ranges I will plug into my algorithm.

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Post #: 23

RE: B-17 & B-24 - 9/25/2012 12:40:48 AM

treespider

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Having had another night to digest some data lets walk through the B-17F

A clean B-17F loaded for Transfer with Bomb Bay Tanks and Max Fuel has a GROSS WEIGHT of 65,000 lbs with 3612 Gallons of Fuel. Referencing the Flight Operations Chart for a GROSS WEIGHT of 65,000lbs we find our best Transfer Range is 2660 Nautical miles - 67 hexes.

Examining Fortress Against the Sun, Osprey's B-17 Units of the Pacific, the Crowood book and our Flight Manual our current load of 8x500lb bombs is fairly accurate. I saw several references to missions with eight bombs. The bomb bay in the B-17 had 4 stacks - the two outer stacks allowed 2x500 each and the center two stacks allowed up to 4x500 each. So we allow for 8x500lb bombs as our standard load.

Looking at our Flight Manual the "Standard" Load was 57,700 lbs. That load is referenced as Load Condition IV, and includes a basic weight of 41,300 (which includes crew, MGs, Ammo, Misc Equipment, etc), 6000 lbs of bombs, and 1732 gallons of fuel ...bringing or total weight to 57,700. However we are going to carry 2000 lbs fewer of bombs so our total weight is 55,500lbs.

Referencing the Flight Operations Chart for 55,000-60,000lbs we find that with 1732 gallons of Fuel our Best Cruising Range is c.1220 nautical miles. Plugging 1220nm into the algorithm which accounts for forming formation etc we arrive at an effective NORMAL range of 821nm - 11 hexes out/back.

Dropping or bombload to 2000lbs for extended range takes us to the 50-55,000lb Flight operation chart which allows for 1300nm as our best range. Plugging 1300nm into the algorithm we get an effective EXTENDED Range of 935 miles - 12 hexes out/back.

However by adding a "Drop Tank" we can extend our ranges with an increase use of supply...something we don't have in stock for the heavies. For DT NORMAL we will use a DROP TANK DEVICE but we'll assume this represents extra wing loading of fuel instead of a BOMB Bay Tank which puts us into Load Condition III and 2812 gallons of Fuel with a total GROSS WEIGHT of 62,200 lbs. 2812 Gallons of fuel (minus the chart indicated 212g not used for flight) provides for a best cruising range of 1820 nm. Plugging 1820nm into the algorithm which accounts for forming formation etc we arrive at an effective DT NORMAL range of 1225nm - 16 hexes out/back.

For DT EXTENDED we will use a Bomb Bay Tank...which allows for 4x500lbs plus tank. Our Gross Weight will be 65,000lbs...with max Fuel our best Cruise range is 2390nm. Plug into algorithm we get 1719nm - 22 hexes out/back.

In summary - let's compare to our stock B-17F.

Stock -
Transfer Range - 2130nm - 54 hexes
Rng Normal - 990nm - 13 hexes out/back
Rng Extended - 1230nm 16 hexes out/back

No DT in Stock so supply costs are standard.

In my mod -
Transfer Range w/ DT - 2660nm - 67 hexes
Rng Normal - 821nm - 11 hexes out/back
Rng Extended - 935nm - 12 hexes out/back
DT Normal - 1225nm - 16 hexes out/back
DT Extended - 1719nm - 22 hexes out/back

In my mod the B-17 can have a further range than STOCK albeit at an increased use of supply.

Next up an analysis of the B-24.

< Message edited by treespider -- 9/25/2012 12:42:02 AM >

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Post #: 24

RE: B-17 & B-24 - 9/25/2012 2:07:40 AM

witpqs

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My immediate observation is that cutting the bomb load in half gets you an extra 1 hex of mission radius?? That's counter-intuitive.

My second observation is that the stock ranges seem to be a combination of the "Rng" and "DT" calculations you've done. It seems like you just validated the stock ranges for that aircraft.

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Post #: 25

RE: B-17 & B-24 - 9/25/2012 2:12:44 AM

treespider

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Now lets walk through the B-24D

A clean B-24D loaded for Transfer with Bomb Bay Tanks and Max Fuel has a GROSS WEIGHT of 60,000 lbs with 3664 Gallons of Fuel. Referencing the Range Charts for a GROSS WEIGHT of 60,000lbs we find our best Transfer Range is 4045 Nautical miles - 102 hexes.

We'll make the assumption that our Standard load of 10x500lbs is accurate.

Looking at our Flight Manual the "and referencing the Gross Weight Nomogram and assuming Main Fuel cells only our Payload will be 6521lbs with a crew of 6 and 2364g of Fuel. Our Gross Weight is 55,000 lbs. Refering to our 50,000lb range chart w/ 5000lb payload and interpolating our best range works out to 2422 nautical miles. Plugging 2422nm into the algorithm which accounts for forming formation etc we arrive at an effective NORMAL range of 1630nm - 21 hexes out/back.

Dropping or bombload to 2500lbs for extended range and interpolating finds an Extended range of 2555nm. Plugging 2555nm into the algorithm we get an effective EXTENDED Range of 1837 miles - 23 hexes out/back.

Now let's add fuel by adding a "Drop Tank" we can extend our ranges with an increase use of supply...something we don't have in stock for the heavies. For DT NORMAL we will use a DROP TANK DEVICE but we'll assume this represents extra wing loading of fuel instead of a BOMB Bay Tank. This puts us into Load Condition 2 and 2814 gallons of Fuel. 2814 Gallons of fuel provides for a best cruising range of 2936 nm with that load. Plugging 2936nm into the algorithm which accounts for forming formation etc we arrive at an effective DT NORMAL range of 1977nm - 25 hexes out/back.

For DT EXTENDED we will use a Bomb Bay Tank...which allows for 5x500lbs plus tank. Our best Cruise range is 3490nm. Plug into algorithm we get 2510nm - 32 hexes out/back.

In summary - let's compare to our stock B-24D.

Stock -
Transfer Range - 2590nm - 65 hexes
Rng Normal - 1300nm - 17 hexes out/back
Rng Extended - 1630nm - 21 hexes out/back

No DT in Stock so supply costs are standard.

In my mod -
Transfer Range w/ DT - 4045nm - 102 hexes
Rng Normal - 1630nm - 21 hexes out/back
Rng Extended - 1837nm - 23 hexes out/back
DT Normal - 1977nm - 25 hexes out/back
DT Extended -2510nm - 32 hexes out/back

In my mod the B-24 can have a further range than STOCK.

On a side note these revised ranges would correspond to mission capabilities referenced in Fortress Against the Sun on page 361. USAAF aircraft bombed Tarawa on July 27, 1943 using 6 B-17s and 9 B-24s. The B-17's had to stage from Espiritu Santo to Funafuti to carry out the raid whereas the B-24's flew direct.

Espirtu Santo to Tarawa - 27 hexes (within DT Extended for B-24).
Funafuti to Tarawa - 19 hexes (within DT extended for B-17).

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Post #: 26

RE: B-17 & B-24 - 9/25/2012 2:13:59 AM

treespider

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quote:

ORIGINAL: witpqs

My second observation is that the stock ranges seem to be a combination of the "Rng" and "DT" calculations you've done. It seems like you just validated the stock ranges for that aircraft.

Keep in mind though my aircraft will use DT for the longer ranges which will require additional supply.

< Message edited by treespider -- 9/25/2012 2:22:44 AM >

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Post #: 27

RE: B-17 & B-24 - 9/25/2012 2:21:53 AM

treespider

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quote:

ORIGINAL: witpqs

My immediate observation is that cutting the bomb load in half gets you an extra 1 hex of mission radius?? That's counter-intuitive.

Well consider that 2000lbs is roughly only 3.6% of GROSS Weight in a 55,000 lb aircraft, but you get a 2 hex increase in range (22->24) thats a 9% increase.

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Post #: 28

RE: B-17 & B-24 - 9/25/2012 2:39:51 AM

witpqs

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quote:

ORIGINAL: treespider

quote:

ORIGINAL: witpqs

My second observation is that the stock ranges seem to be a combination of the "Rng" and "DT" calculations you've done. It seems like you just validated the stock ranges for that aircraft.

Keep in mind though my aircraft will use DT for the longer ranges which will require additional supply.

More strain on supply is a good thing. Given that DT vs Rng was averaging out to stock, I was wondering if it was worth the trouble.

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Post #: 29

RE: B-17 & B-24 - 9/25/2012 2:41:58 AM

witpqs

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quote:

ORIGINAL: treespider

On a side note these revised ranges would correspond to mission capabilities referenced in Fortress Against the Sun on page 361. USAAF aircraft bombed Tarawa on July 27, 1943 using 6 B-17s and 9 B-24s. The B-17's had to stage from Espiritu Santo to Funafuti to carry out the raid whereas the B-24's flew direct.

Espirtu Santo to Tarawa - 27 hexes (within DT Extended for B-24).
Funafuti to Tarawa - 19 hexes (within DT extended for B-17).

That sort of realism I like very much!

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Post #: 30