REPUBLIC AVIATION PERFORMANCE DATA - P-47 "M" and

[wmaxt]

Originally Posted by Soren

Also the -47M didnt beat the "Frank" in the climb, but by the traditional team-work in which even a P-38 could wax any Jap. single seat fighter. (The Jap pilots were real poor at teamwork )

Your right even inexperianced P-38 pilots with tactics (boom and zoom) and teamwork had little trouble with Japanese single seat aircraft. A number of experianced pilots could, even with early P-38s, take the Japanese on 1:1 in any situation.

wmaxt

[Soren]

Compared to the amount of fuel it was designed to be able to carry for missions in the PTO from, say Le Shima, not much! If operating in the ETO, there would be no reason to fill an "N" model's internal fuel tanks to maximum when they could carry drop tanks to the hot spot, drop the tanks, engage the enemy and still make it back using far less than 570 gallons.

Use drop tanks instead of internal fuel ? That would be even more expensive...

I could concede that the -47N might not carry more than 75% of its full internal fuel load in the ETO, but no less. It needs a good chance of making it home again.

"Also the -47M didnt beat the "Frank" in the climb, ..."

Soren, the P-47M model never flew in the PTO. I'm not sure what the climb rate of the Ki-84 was but have read that it was 3,600fpm (I no not know at what altitude this figure is for or even if it is accurate).

I know, meant the -47N, accidently typed "M"

As you could see I was responding to your saying: The P-47N did, however, do quite well in the PTO, waxing late war Japanese rice rockets like the Ki-84 Frank which, I might add, boasted a very high rate of climb

[Soren]

Anyway since you asked DAVID, yes I do think the Ki-84 would out-climb even the -47M:

-47M
Power-loading: 4.74 lbs/hp.
Wing-loading: 43.1 lbs/sq.ft.

Ki-84
Power-loading: 4.18 lbs/hp.
Wing-loading: 35.19 lbs/sq.ft.

[FLYBOYJ]

Originally Posted by plan_D

It's his Uncles job, he was a gifted amateur as I can tell from the story.

Oh he was! "Uncle Joe" washed out because he wasn't too serious about flying and was made a Flight Officer immediately after "resigning" from pilots training and agreeing to become a bombardier. He told me it also paid more. My mom tells me he was a real ladies man and was the type of guy who had 2 girls on each arm on a Saturday night. Unfortunately he was badly injured in a B-24 crash in Idaho, he was on a training mission and was the only survivor on an 11 man crew! Attached is 2nd Lt Joe Colon as an enlistee....

Back to the subject....

Do you guys really believe that ETO P-47s would be sent out without full tanks? There has always been a rule of thumb to land with 1/2 hour reserves in your tanks if possible. I would think that unless there is an ordnance issue anytime an aircraft went out on a mission they did so with full tanks all around!

[Soren]

Originally Posted by FLYBOYJ

Back to the subject....

Do you guys really believe that ETO P-47s would be sent out without full tanks? There has always been a rule of thumb to land with 1/2 hour reserves in your tanks if possible. I would think that unless there is an ordnance issue anytime an aircraft went out on a mission they did so with full tanks all around!

I agree FLYBOYJ.

[DAVIDICUS]

Well, Flyboy, the P-47N wasn't an ETO P-47. We were just entertaining the hypothetical that it was.

The P-47N had a far greater internal fuel capacity than the "M" model as it was specifically designed for escort duties in the PTO where the distances involved were far greater than the distances involved in escort duties in the ETO.

If the "N" model had been deployed to the ETO as opposed to the PTO, why would they use full internal tanks?

The P-47N's internal fuel tank capacity enabled it to carry 2,500lbs of fuel over and above the internal fuel tank capacity of the "M" model.

Soren said, "Use drop tanks instead of internal fuel ? That would be even more expensive... "

And your point is?

"I could concede that the -47N might not carry more than 75% of its full internal fuel load in the ETO, but no less. It needs a good chance of making it home again."

I appreciate the concession but would apprise you of the following. The "M" model had no different internal fuel loading than the preceding "D" model. A P-47N, even at 75% internal fuel capacity, carries 16% more internal fuel than the full internal fuel load of the "M" and "D" models. In fact, the P-47N needs but 64% of its internal fuel capacity to equal 100% of the internal fuel capacity of the "M" and "D" models.

With respect to the climb rates of the P-47M and Ki-84, as I indicated, I really don't know. I do know that relying solely on power and wing loadings is a problematic method of estimating climb rates as evidenced by much of the debate on this thread that preceeded my posting official performance test data from Republic Aviation. My favorite example, which you have heard several times now, is the change in climb rate for the P-47D after the paddle blade propeller was installed which resulted from no change in weight, horsepower or wing area.

Different aircraft will have wing designs that afford different amounts of lift. Different aircraft will have differential efficiencies with respect to their propellers' abilities to move air. Different aircraft will have different drag coefficients. Lastly, unless you get a hold of reliable data, you can't rely on the power, weight and horsepower figures to begin with.

I have a book that lists the following data for the Ki-84:

Wing area - 226 sqft

Weight - 5,864lbs

H.P. - 1,900

The climb rate is just listed at 3,600fpm

You do the math. It certainly doesn't coincide with the power and wing loading data you presented. (My point is not that your data is incorrect just that there is a lot of different data out there that isn't reliable)

BTW - Where did you get your power and wing loading figures from?

[FLYBOYJ]

Originally Posted by DAVIDICUS

Well, Flyboy, the P-47N wasn't an ETO P-47. We were just entertaining the hypothetical that it was.

I understand that. I just couldn't see the thought of going out on a mission over Europe in any fighter/ fighter bomber aircraft and not having the aircraft bagged full of fuel, unless there was a bomb load/ takeoff weight requirement, but I would only see that happening in multi-engine bombers.

[plan_D]

It'd have full internal fuel and no drop tanks. It's extremely rare for fighters to go up without full internal fuel.

[Soren]

Originally Posted by DAVIDICUS

Soren said, "Use drop tanks instead of internal fuel ? That would be even more expensive... "

And your point is?

You mean you don't know ? Think about it DAVID, what would be the most economical and safe way...

Originally Posted by DAVIDICUS

Different aircraft will have wing designs that afford different amounts of lift. Different aircraft will have differential efficiencies with respect to their propellers' abilities to move air. Different aircraft will have different drag coefficients. Lastly, unless you get a hold of reliable data, you can't rely on the power, weight and horsepower figures to begin with.

Your absolutely correct DAVID, and therefore I acquired that data before I posted those stress-load figures.

First of all I think we can clearly agree that the Ki-84 is more aerodynamically clean than the P-47, right ?

Second comes the statistic Figures:

Ki-84
Empty weight: 5,864lbs.
Loaded weight: 7,955lbs.
Max loaded weight: 8,576lbs.

Wing area: 226 sq.ft.
Wing span: 36' 10".

Engine: Nakajima Ha-45 Radial.
Power: 1900 HP.

Power-loading: 4.18 lbs/hp.
Wing-loading: 35.19 lbs/sq.ft.

The Ki-84's airfoil was supposedly overall thicker than the Ki-56 and Ki-61's while using the same shape(NACA 2R1 16 - NACA 2R1 or NACA 24000), resulting in a airfoil thickness ratio of about 16-17% at the root and about 10% at the tip. So the Ki-84's wing has a higher CL-max than any of the P-47's, and on top of that the Ki-84 has wing aspect ratio of 6.0 while the P-47 has a max ratio of 5.62. All this is more than enough to totally negate any prop design advantage to the P-47.

So yes, in reality the Ki-84 would outclimb even a P-47M, and certainly the P-47N.

In initial climb rate, the P-47M might have a small advantage because of its very high top speed, but the Ki-84 will quickly overtake and clearly beat the -47M in a sustained climb.

Originally Posted by DAVIDICUS

I have a book that lists the following data for the Ki-84:

Wing area - 226 sqft

Weight - 5,864lbs

H.P. - 1,900

The climb rate is just listed at 3,600fpm

What book is that ? And why does it quote the Ki-84's empty weight figure ?

Originally Posted by DAVIDICUS

You do the math. It certainly doesn't coincide with the power and wing loading data you presented.

No its much more favorable to the Ki-84 than the data I presented, but unfortunately also wrong.

My data comes only from a few books (listed below) and mostly from websites, as not much is written about this aircraft, so how accurate it is, is uncertain. However weight and HP figures are aquired from NACA, so they should be correct.

Sources: "The Complete Encyclodepia of World Aircraft - 1997" and a very old book "Japanese Aircraft of the Pacific War - 1979"

[DAVIDICUS]

"You mean you don't know ? Think about it DAVID, what would be the most economical and safe way... "

When I said, "And your point is?" I was being tongue in cheek Soren. (I don't make widespread use of emoticons as you do so comedy runs the risk of being misunderstood) We are talking about war here. Let's not be naive. Considerations of expense, economy and safety often take a back seat to other considerations that make for results that are more expensive, and dangerous.

In further contravention of your point, I could easily argue (which I have already done above) that, hypothetically speaking, sending pilots into combat in the ETO with P-47N's that are unnecessarily heavy, due to a reliance on their massive internal fuel capacity designed for operations in the PTO and not the ETO, would in fact be more expensive and dangerous in terms of more shot down aircraft, lost pilots and lower morale than the cost of utilizing jettisonable drop tanks and a much reduced internal fuel load. (Remember that the "N" model needs but 64% of it's internal fuel capacity to equal 100% of the internal fuel capacity of the "M" and "D" models.)

In fact, if the "N" were sent into combat under a Normal Gross Weight of 13,854lbs (that would be the empty weight of 10,998lbs plus 2,856lbs of ammunition and fuel), it's climb rate would be very close to the "M" model's at Combat Gross Weight (13,275lbs) which we know to be 3,775fpm at 5,000ft.

See my prior post on this thread:

A full internal ammunition and fuel load in an "M" model weighs 2,833lbs.

A full internal ammunition and fuel load in an "N" model weighs 5,332lbs.

The "N" model would thus carry an additional 2,500lbs (2,499lbs) of fuel over and above the "M" model (under circumstances where the ammunition load is the maximum) in "Combat Gross Weight" configuration.

See also my prior post on this thread:

Given the "M" model's ability to cliimb at 3,775fpm at 5,000ft, it would appear likely that the maximum climb rate at sea level would be in excess of 4,000fpm. (That, of course, would be under a "Combat Gross Weight" loading. Under a "Normal Gross Weight" loading, the climb rate would be significantly higher.)

Given the "N" model's mere 579lb heavier weight in "Normal Gross Weight" configuration and lower wing loading of 43lbs as opposed to the "M" model's 44.25lbs, I would expect the "N" model to have a climb rate within 100fpm or so of the "M" model's figures reflected above.

Soren, I will accept your Ki-84 data. I have never argued with you on the data you presented. To quote my prior post, "With respect to the climb rates of the P-47M and Ki-84, as I indicated, I really don't know." Additionally, when I quoted those figures from the book I have, the purpose was expressly set out as, "(My point is not that your data is incorrect just that there is a lot of different data out there that isn't reliable)".

BTW - The book I quoted the figures I posted from was "Axis Aircraft 1939-1945" by Charles Dumont.

[Soren]

DAVID all else being equal, fighters did not fly out on half full or even 3/4 full internal fuel tanks, that's just not the way it was done. And they certainly didn't fly on half full internal fuel tanks coupled with drop tanks..

So while the -47N might have had an excessive amount internal fuel for 'one' mission, it would still be fully fueled up in case of any emergency.

[DAVIDICUS]

I would be inclined to agree with you if were talking about the ETO and the aircraft designed for that theatre of operations like the "M" or "D" model. The hypothetical we are entertaining, however, is that of a P-47N model in the ETO.

Specifically, I do not agree because carrying the maximum fuel load that an "M" or "D" model would carry would not subject the "N" model to any additional fuel related threat or danger not borne by the "M" or "D" models. However, ladening the P-47N with thousands of extra pounds of fuel over and above the maximum fuel load of the "M" and "D" models would expose the P-47N to additional threats not borne by the "M" or "D" models.

At any rate, why don't we just agree to disagree?

[FLYBOYJ]

Originally Posted by DAVIDICUS

However, ladening the P-47N with thousands of extra pounds of fuel over and above the maximum fuel load of the "M" and "D" models would expose the P-47N to additional threats not borne by the "M" or "D" models.

David, there is never such thing as "extra fuel" unless you're on fire!

Seriously at up to 200 gph, there really isn't such thing!

[DAVIDICUS]

Sure there is Flyboy. If you are flying a P-47N to and from a target 350 miles away, why wouldn't you load up on 996 gallons gallons of fuel in the internal and external tanks? (Yes, that's right. That's the maximum internal and external fuel load carried ny the P-47N) It would be for the same reason you wouldn't load up the internal tanks to a 570 gallon capacity. Too much weight.

When you're in a fur ball with late model Me-109's and Fw-190's, the last thing you'd be thankful for is that extra margin of safety of being able to fly to Greece should you not feel like returning to base.

Where does that 200gph figure come from? Is that in the Pilot manual?

[FLYBOYJ]

Originally Posted by DAVIDICUS

Sure there is Flyboy. If you are flying a P-47N to and from a target 350 miles away, why wouldn't you load up on 996 gallons gallons of fuel in the internal and external tanks? (Yes, that's right. That's the maximum internal and external fuel load carried ny the P-47N) It would be for the same reason you wouldn't load up the internal tanks to a 570 gallon capacity. Too much weight.

When you're in a fur ball with late model Me-109's and Fw-190's, the last thing you'd be thankful for is that extra margin of safety of being able to fly to Greece should you not feel like returning to base.

That's, funny But I gotta disagree David. Weight comes into the equation on fighters/ fighter bombers when trying to lift something (like bombs) or if your operating out of a high elevation airport on a short strip. Once in the air, utopia is to be over the target, full of gas. Sure you're going to be able to maneuver better if you were on half tanks, but I'm willing to bet dollars to donuts that most WW2 fighter pilots would trade that little margin of maneuverability for endurance - whether it be used over target or to be able to make it home!