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XP-39 II - The Groundhog Day Thread
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Believe me, you are not damaging anyones reputation but your own.
FLYBOYJ
"THE GREAT GAZOO"
And agree - to say something is "overweight" based on power to weight is only comparable to similar aircraft of the day. My point.
What are you willing to do without? A6M and BF109 were essentially minimalist machines, both more susceptible to battle damage than the US machines mentioned, which can't be accused of flimsyness. "Hell for stout" was our motto, and we had this tendency to "gadgetize" anything with wings.
Zero achieved its performance with lightness and slickness and "zero" protection, on a rather weak engine, while the Messerschmitt did it with small size and a cutting edge powerplant. Spitfire was an aerodynamic tour de force with an exceptionally fine engine, but a little more fragile than US was comfortable with. Built to US structural standards by anyone other than Reg Mitchell, our X-spurt friend would be calling it porky.
You can't have your cake and eat it too. Larry Bell was not a Horikoshi, or a Mitchell or a Messerschmitt, witness missed opportunities such as the carburetor air intake, or adjusting wing positioning to ameliorate the CG issue.
Several suggestions have been made to lighten the early P39, most of which are impractical for CG, structural, or operational reasons, would not at the time have been recognized as necessary or desirable, and come with overly optimistic claims of performance enhancements. What I see is still a sow's ear.
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No, just a plain understanding of written English. The L-133 was a conformal design - the wing thickness altered to allow it to engulf the axial engines in the wingroots. That means the wing was a lot thicker at the root, then thinned out toward the midsection, and was finally a conventional wing much further out. The P-80s is a simple, straight wing from the wingroot right to the tip.
You use a shovel to type? I'm impressed! Instead, I'll just put up some 3-views of the L-133 and the P-80, you can compare them to the 3-view of the XP-59B, and then you can shovel off a reply telling us how the much bigger L-133 is somehow closer to the P-80 than the XP-59B:
And I'm sure, after several decades of repeating the company line, those Lockheed employees actually believed it.
Actually, the authorities took the design away from Bell because Bell's design staff were already overloaded with other projects, just as the authorities had not given it to Lockheed to start with because Lockheed were too busy sorting out the flaws with the P-38. Now, personally, I think that was a good thing because the P-38 was really needed for the PTO, and the resulting P-80 was very good design. Had Germany held out longer then the P-80 would have been a far better fighter for the USAAF in the ETO than the Bell P-83 could have been, though the P-83's superior range might have made it the better choice for the PTO if the Manhattan Project had not succeeded. The idea that Bell were massively incompetent, and Lockheed were somehow simply devine, simply doesn't gell with the history of the P-38's development alone.
I don't think 2 airplanes looking alike means they were designed by the same people. All ww2 single engine fighters had the engine in the front (except the P39)etc. There are only so many ways to do an airplane that will fly. All current pickup trucks look basically alike.
P-39Ds were having less than 1150 HP at 12000 ft (sometimes under 1100 HP at that altitude). Later the situation slightly improved, engines were indeed making 1150 HP at 12000 ft.
Spitfire V was enjoying ~1350 HP at 12000 ft.
Bf 109F4 (fully rated engine) and early G (de-rated, 2600 rpm operation) = 1350 PS or 1300 PS at 12000 ft, respectively.
At 20000 ft:
P-39 D-K: 850-870 HP
Spitfire V: ~1050 HP
The 109s from above: ~1150 PS or ~1240 PS
Non-turbo V-1710 was a decent engine, but it was not as good engine as Merlin or DB 601/605 were.
I completely understand your point, but I guess there is a middle ground somewhere which is where aircraft manufacturers play. Of course we all want armor and self sealing fuel tanks along with good weapons, but who here if given the choice between flying a Zero and F2F-3 Buffalo against each other 1 on 1 would choose the F2F-3? When your limited to engines less than 1200 hp your simply limited on what you can carry or at least how well you can carry it.
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FLYBOYJ
"THE GREAT GAZOO"
You're making assumptions based on non-scale 3 view drawings that were done by a graphic artist! That's laughable!
No, again I'll tell you those employees I knew WORKED on the project - they were in the Skunk Works AS I WAS FOR 3 YEARS!
Lockheed XP-80 "Lulu Belle"
Well show us proof that the government "took the design" away from Bell and gave it to Lockheed!!!! And what "projects" was Bell working on that made them sooooo busy? And for sorting out P-38 "flaws," yea, Lockheed was so busy that they managed to build something like 35 P-38s a day, build B-17s down the street (literally) at the Vega plant and open up the P-80 production line right along side the P-38 line!
Oh - and they were building Constellations and starting the P2 Neptune program at the same facility!!!
Sorry if you have a hard time believing history
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FLYBOYJ
"THE GREAT GAZOO"
You're too stupid to play here - bye-bye!
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Tsk, tsk, did you actually banish him? Too bad, he was fun to watch! Worth a chuckle now and again, even if he did insult your former employer.
FLYBOYJ
"THE GREAT GAZOO"
I know he was entertaining but he was warned twice. I was intrigued about his ability to determine dimensions and loft data from internet 3 view drawings!
People like that not only entertain us they keep us on our toes and keep our diplomacy skills physically fit.
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FLYBOYJ
"THE GREAT GAZOO"
Yep! Along with patience from your mods and admins!
GregP
Major
I have a book, actually two, on lofting, and though I COULD get through it, I'm not needing to loft just now. But, I can tell you that math for good lofting, while not too complicated, is also not simple, and you're NOT going to get it from a drawing. I do 3-views myself, and I use a bezier tool for lofting. They might have back in the day, too, IF they had been available ... but they weren't. So, they had to do actual lofting.
Here's one of my efforts:
and I can tell you, the lofting was NOT done with classic lofting data. I used a bezier tool. It ain't a bad drawing, but it's also not 100% scale. The rivets are close, but not exact in number. the lines could be off by 1/4 inch or so, the NAA logo is my own reproduction, not an official company logo. I could go on, but this is good enough for a museum drawing or an illustration in a book.
I would not use it for scale documentation ... although I DID compete in RC aerobatics (not scale) for some years a couple of decade back (RC Pattern), I can tell you that the scale judges I used to see working at contests would not know what was not to scale in my drawing above. Some people in here might.
There is ONE rather glaring error in the drawing above ... the side view. Anybody want to make a stab at it?
Here's one of my efforts:
and I can tell you, the lofting was NOT done with classic lofting data. I used a bezier tool. It ain't a bad drawing, but it's also not 100% scale. The rivets are close, but not exact in number. the lines could be off by 1/4 inch or so, the NAA logo is my own reproduction, not an official company logo. I could go on, but this is good enough for a museum drawing or an illustration in a book.
I would not use it for scale documentation ... although I DID compete in RC aerobatics (not scale) for some years a couple of decade back (RC Pattern), I can tell you that the scale judges I used to see working at contests would not know what was not to scale in my drawing above. Some people in here might.
There is ONE rather glaring error in the drawing above ... the side view. Anybody want to make a stab at it?
fubar57
General
Off to Google "lofting". Knowing Google, I'll probably get, "relaxing in the attic"......................................................
Side view is missing guns?
GregP
Major
Hi Biff, Yup, that was QUICK. I didn't notice it myself until I posted this! At least I can go back and fix it easily.
My point was that FlyboyJ is correct; you ain't gonna' get accurate interior spaces, lofting data, or even 100% correct lines from a small, non-factory 3-view drawing that wasn't used in the actual production process.
So, while I think my P-51 is pretty decent, you wouldn't want to drill CNC holes using my drawing for a reproduction full-scale aircraft. I HAVE made new skins for a WWII warbird. But I didn't use a drawing. I copied an old, original skin by laying it flat over a new piece of Aluminum, drilling and using clecos through both skins to copy the rivet hole placement.
Cheers!
Hey Fubar 57, lofting is the process of forming the curves between skins, such as where the wing joins the fuselage. Basically they join with many straight lines and the curve is formed by following the outside of the lines. Sort of like below, where many straight lines are used to come up with a good-looking, streamlined curve between two surfaces. The curve shown is not lofted correctly, but is illustrative of what I mean. I didn't calculate the lofting lines ... I just threw some lines in and followed the curve as an illustration. If you do, maybe, 25 of these, correctly ... each one different, you come up with the wing fairings between the wing and fuselage. A good example might be the fairings between the wing and fuselage of a P-36.
Or lofting might be "relaxing in the attic ... with a good, cold beer!"
Lofting was BC ... before computers and, actually, before computers with decent software on them. See the wing fairings on the P-36 below. All done with actual lofting.
Nothing magic about it, but also not as simple as you might think to get the exact curves right.
Cheers again!
My point was that FlyboyJ is correct; you ain't gonna' get accurate interior spaces, lofting data, or even 100% correct lines from a small, non-factory 3-view drawing that wasn't used in the actual production process.
So, while I think my P-51 is pretty decent, you wouldn't want to drill CNC holes using my drawing for a reproduction full-scale aircraft. I HAVE made new skins for a WWII warbird. But I didn't use a drawing. I copied an old, original skin by laying it flat over a new piece of Aluminum, drilling and using clecos through both skins to copy the rivet hole placement.
Cheers!
Hey Fubar 57, lofting is the process of forming the curves between skins, such as where the wing joins the fuselage. Basically they join with many straight lines and the curve is formed by following the outside of the lines. Sort of like below, where many straight lines are used to come up with a good-looking, streamlined curve between two surfaces. The curve shown is not lofted correctly, but is illustrative of what I mean. I didn't calculate the lofting lines ... I just threw some lines in and followed the curve as an illustration. If you do, maybe, 25 of these, correctly ... each one different, you come up with the wing fairings between the wing and fuselage. A good example might be the fairings between the wing and fuselage of a P-36.
Or lofting might be "relaxing in the attic ... with a good, cold beer!"
Lofting was BC ... before computers and, actually, before computers with decent software on them. See the wing fairings on the P-36 below. All done with actual lofting.
Nothing magic about it, but also not as simple as you might think to get the exact curves right.
Cheers again!
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3 view looks good Greg.
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I must admit members like that are funny, that one we had a few weeks ago that was convinced the USA won the air war single handily was a scream, there are rules we all have to follow but the fanatical ones are hilarious to listen too.
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