Talk:Convair B-36 Peacemaker

Engine oil

Each had a 100 U.S. gallon (380 L) tank, but the tank was sometimes insufficient, and the engine would have to be shut down.

Last night I read in Jenkins' "Magnesium Overcast" that the jet engines had this problem. IIRC the exact wording was "engine operating time was limited by the amount of oil carried." I haven't seen references to the recips having to be shut down because the oil tank went dry.

Meguire, 11.6.05. I have read of an R-4360 having to be shut down because its oil ran out. Oil consumption sometimes led to B-36 missions being aborted. But I have never seen anything about oil and the J47. In fact, I have never read anything about jet engines consuming any oil whatsoever.

Picture

The picture currently in place can never be loaded by my computer, and once I access the B-36 article, all other pictures become un-loadable. Should I change it?--→Iñgólemo←

I think you're the only one. You might be better off working out why your computer has problems with this image. What OS/browser combo are you running? —Morven 07:47, Aug 5, 2004 (UTC)

I use a Windows 2000 Business edition, with Microsoft Internet Explorer. The internet connexion is via an SB4100 Cable Modem. --→Iñgólemo←

It sounds like this may be your problem: http://support.microsoft.com/?kbid=817177

Lovely buggy M$ software. —Morven 20:00, Aug 18, 2004 (UTC)

Yeah, that sounds right. Whenever I get on this page, the loading progress bar always stops at about 40%.--→Iñgólemo← 22:58, 2004 Aug 20 (UTC)

"Placeholder engines"

What on earth are ""placeholder" engines"? →Iñgōlemo← ^talk donate 03:44, 2005 Mar 8 (UTC)

I meant that they were only temporary, until they could be replaced by the intended engines. —Morven 05:04, Mar 13, 2005 (UTC)

Thrust/weight units

Someone recently changed thrust/weight from a unitless form to lbf/lb and N/kg. According to WikiProject Aircraft policy with regards to specifications, this should be expressed as a ratio (see WP:Air and Template:Airspec-imp). Because weight (not mass, weight) is a measure of gravitational force, it should be measured in the same units used to measure the thrust of the engines. When thrust is divided by weight, you are left with a ratio. Expressing it in a unitless ratio form is useful in a number of ways. For example, if the ratio is higher than one, the aircraft is powerful enough to climb vertically upwards.

If you still think that the units of this statistics should be changed, it should probably be discussed on the talk page (WP talk:Air) of WikiProject Aircraft, rather than here. That way, we can re-examine policy for all articles, not just this one. →Iñgōlemo← ^talk 04:28, 2005 Mar 13 (UTC)

Congratulations

To all who helped this become a featured article, congratulations. That any of my early rewrite survives amazes me; thank you all for fixing all the errors I left in. —Morven 09:48, Apr 3, 2005 (UTC)

Lead

Please reduce Wikipedia:Lead, 3 paras is the maximum size. --Piotr Konieczny aka Prokonsul Piotrus ^Talk 15:44, 6 Jun 2005 (UTC)

Table format

File:B36-table.png

Hey anonymous, I figured out the problem with the table. I checked the display in MSIE/Windows, and I see that it doesn't support the CSS properly. Other browsers display the table something like this screen shot from Safari.

In the long run, I'd like to make the "standard" table format a lot better than it is. All the grid lines are usually unnecessary, and just distract from the content. I'll have to give this more thought. —Michael Z. 2005-11-3 21:12 Z

Anonymous was me. The particular computers I was using get a read timeout nearly all the time, so I don't always bother with logging in.

With regards to the format, I see where you're coming from. The advantage with the "class=wikitable" markup is that it's simpler and that everyone can read it, not just the ones with real web browsers. The disadvantage, as you said, is that your format looks better. I prefer the wikitable format because, much as I hate myself for saying this, we do need to ensure that the microserfs can read Wikipedia also. Anyway, I'll leave the judgement on which format to use up to you. Ingoolemo ^talk 06:41, 4 November 2005 (UTC)

Rewrite

Philip Meguire, 22.10.05: I have rewritten nearly every sentence of this article and extensively reorganized its content, a labor of love, to be sure; this Baby Boomer has vivid childhood memories of the Cold War. I've added some links and take responsibility for explaining why mounting a R-4360 engine in a pusher configuration made it more likely that it would catch fire. I have also added text explaining why the B-36 was a key technology of the early Cold War and its nuclear arms race: there is no point to building the H-bomb unless you can deliver it. I was never in the Service, nor am I an aerospace engineer. Hence those of you more expert than I should feel free to correct and expand my work.

I'm planning a rewrite of my own in a few weeks. Because you put so much work into the article, I'll be sure to include a detailed explanation of why I made the changes I did. Ingoolemo ^talk 22:20, 8 November 2005 (UTC)

Too long?

Note that Wikipedia gently complains that the article might be too long. I've tried to address that a bit, but dare not throw out anything researched by others. Philip Meguire

That is a standard system message generated when an article's source (the wiki text you see when you click the 'edit' tab) approaches or exceeds 32 kB. In the past, this has prevented users with 'now-seldom-used browsers' from editing articles; because of the edit links next to section headings, this problem is largely gone. Wikipedia:Article size advises that '[a limit of 32 kB] is considered to have stylistic value in many cases'. However, this is just a rough guideline. If an article can be written with reasonably long sections and subsections that cover most of its various topics and subtopics, than it should probably be left alone—even if it exceeds the 32 kB limit. Remember, the limit is just a number; it's the readability and the stylistic virtues that really matter. Ingoolemo ^talk 06:52, 11 November 2005 (UTC)

Yeah, it happens. It's no big deal. --Apyule 16:07, 11 November 2005 (UTC)

A horsepower rating for the J47.

I would like a better grasp of the extent to which power was increased by adding 4 J47s. This requires coming up with a power rating for both the R-4360 and the J47 having the same units. Recips are rated, very conventionally, in units of horsepower. Turbojets are rated in foot-pounds. Now Horsepower = (foot-lbs x velocity in feet/min )/33,000. What velocity to use? I propose the maximum cruising velocity of the B-36J, 660km/hr, which translates to 36,700 ft/min. The factor that converts foot-lbs into horsepower is then 36700/33000 = 1.11. Hence a J47 delivers 5200 x 1.11 = 5770hp. If I am correct, the 4 J47s delivered about 23000 hp. Meanwhile, the R-4360s delivered 6x3800 = 22,800 hp. This suggests that adding the J47s neatly doubled the power of the B-36. I suspect that this increase in power is too much, and that the velocity figure of 36,700 ft/min is too high. But moving forward here will require advice from someone out there. —preceding unsigned comment by Concerned cynic (talk • contribs) 20:11, November 15, 2005

You can't get distance from aircraft's speed since you are not factoring in the contribution of the "six turning," the drag, etc. To get the hp for J47, you have to know its shaft torque and rpm, same as for turboprop and turboshaft engines. I'm not sure there's a simple way to figure out torque from thrust.

Besides that, I think you are going about the whole idea backwards. You need to figure out total thrust, not total horsepower. Here's why: In a prop engine, hp (torque, really) is sent through reduction gearboxes to the propeller whose rotating blades generate lift which is basically thrust. So you need to figure out the thrust generated by the propellers and compare that with thrust provided by the J47s. For prop thrust, you need to know the airfoil characteristics and propeller speeds of B-36 props, so that you can figure out lift. I hope you like math. :) Emt147 05:36, 16 November 2005 (UTC)

Philip Meguire replying. The math is but arithmetic; this is really an exercise in old fashioned aeronautical engineering. Instead of coming up with a horsepower for the J47, let me propose a foot-poundage for the R-4360, as follows. I have no way of finding out the rpm of any turbojet. But the R-4360 is a simpler kettle of fish: the propeller tips were just subsonic. Given that the propeller diameter was 19' 6", that translates to 1025rpm. I also know that the propeller speed was half the engine speed. Hence the R-4360 cruised at a little over 2000rpm. From that fact, and the fact that the R-4360 was rated at 3,800hp, can I back out a foot-poundage for the R-4360? If yes, then I'm home free, because the J47 was rated at 5200 foot-pounds. —preceding unsigned comment by 132.181.160.61 (talk • contribs) 20:47, November 17, 2005

---

The following info, from aerospaceweb.org, cannot be correct.

Thrust (B-36B) 21,000 hp (15,660 kW) (B-36J) 38,460 hp (17,004 kW) plus 20,800 lb (92.5 kN)

Early versions of the R-4360 delivered 3000hp, consistent with a total of 21,000hp. But the most powerful version of the R-4360 delivered 4300hp, so that 6 such engines could have delivered at most 25,800hp, not 38,460hp as claimed. My tentative conclusion is that 38460 is the total horsepower of all 10 engines. If so, the 4 J47s delivered at least 38460-25800=12660hp, or 3165hp apiece. —preceding unsigned comment by 202.36.179.65 (talk • contribs) 05:05, November 18, 2005

Comment: the most powerful R-4360 used on a B-36 (apparently, the B-36 never used the most powerful variant) generated 3,800 hp, so the J47 should have generated something more like 3,900 hp given the power estimate you cite above. Both Joe Baugher's Encyclopedia of American Aircraft and the USAF Museum website cite a 3,800 hp figure for the B-36's engines. Ingoolemo ^talk 23:39, 18 November 2005 (UTC)

Please stop putting 38,000 hp back into the article or I will tag it with questionable information -- B-36 never had 38,000 hp for reasons detailed below. Please take 15 minutes to read the link and educate yourself. Emt147 02:26, 23 November 2005 (UTC)

The exact figure reported in www.aerospaceweb.org is 38,460hp. This far exceeds the power of the 6 R-4360, any variant. But the number is unlikely to have come out of thin air. I presume it refers to the total horsepower of all 10 engines.

Thrust (B-36B) 21,000 hp (15,660 kW) (B-36J) 38,460 hp (17,004 kW) plus 20,800 lb (92.5 kN)

11/22 edits by Emt147

(The same engine powered the B-47.) Unless the B-47 was powered by avgas-burning J47s, this statement is incorrect. It also interrupts the flow of the article. The reader can find out what else used J47s by visiting that page.

That the J47 burned jet fuel (kerosene)when mounted in the B-47, and avgas when mounted in the B-36, is a distinction without a difference, a fact that does not render the statement incorrect. "Interrupting the flow" is a matter of opinion.

. Hence the B-36 in its later years is believed to have enjoyed about 38,000hp, Like I said before, this assertion is incorrect unless 3,800 x 6 is somehow equal to 38,000. Jet engines do not produce horsepower -- they produce thrust. Piston engines produce torque (which can be mathematically coverted to horsepower) which is used to turn propellers which produce thrust (technically, lift in the direction of flight). If you want to give the total power output of a B-36D, you have to talk in terms of thrust, not horsepower.

I invite you to calculate the total thrust produced by all 10 engines, and to incorporate that number into the article. In any event, [1] includes a horsepower calculation for the 747.

, probably a record for a mass-produced aircraft, and was probably the most important jet-piston hybrid aircraft ever made Violates the "neutral point of view" policy. Emt147 17:14, 22 November 2005 (UTC)

Such "policies" I prefer to take with a grain of salt. I go to Wikipedia for relief from the pedantry of my day job :<) I trust no one doubts that (a) jet-piston hybrids were rare, and (b) the B-36 was a significant aircraft in its day.

I agree with these edits. The only way you can add the piston-engine and jet-engine portions together is in terms of thrust - which you can, indeed, convert into horsepower if you wish (since you can calculate the work being done). However, you can't use the piston engine's crankshaft horsepower in that equation, since the figure that can be directly compared is not that, but the thrust actually generated by the propeller.

The 'probably a record' and 'most important' could be in here if they were cited statements. —Matthew Brown (T:C) 17:31, 22 November 2005 (UTC)

For anyone interested, here's a good discussion of why you shouldn't try to do thrust to hp conversions and why you will totally fail even if you try. http://www.aerospaceweb.org/question/propulsion/q0195.shtml

Why not attempt an hp to thrust conversion? At any event, thank you very much for this excellent link, where it is shown that a horsepower figure for an all-jet plane merely requires knowing its cruising speed, the associated throttle setting, and its maximum test stand thrust. The mixed mode engines of the B-36 complicate things, yet I remain optimistic about calculating a number for its total power or thrust. And I bet the total power will fall a little below 40,000hp.

The word probably in this context makes the statement subjective. Any "most important" claim is subjective by default. Ten engines is the most I can think of in a mass-produced aircraft, so I'll stick that back in. Emt147 17:53, 22 November 2005 (UTC)

"Subjectivity" is unavoidable in serious discourse, and thus should be embraced rather than shunned. Also, one man's "subjectivity" is another man's polite caution.