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Your proof and source that the tilten seats were better than G-suits please.
The tilted seats and all probably helped but I find it very hard to believe that it was better than a G-Suit, even an early one.
Again 100% wrong - tilting a seat back and adding food rest WILL NOT cancel out the advantage of the G suit - even the early ones (which aren't much different from the ones we see today), and I don't care if the pilot was sitting on a milk crate.Again why is it necessary to twist what I say ?? I never claimed that the tilted seat heightened footrests were better than the G-suit, just that they about cancelled out the advantage given by the early G-suit. Besides at that period exercise was the best way to withstand G-forces.
Davparlr,
There seems to be something you don't understand;
The load limit for the P-51D is 6.59 G fully loaded, now as to the ultimate I don't know but.
The a/c which can withstand the most G-forces is what matters. So while the P-51 is able to withstand ~96,000 lbs of force it is also heavier than both the 109 190 and therefore has to cope with more weight for every increase in G-forces.
This is also true and since all of these planes would exceed the pilots ability to perform and were very effective in combat, I scratch my head wondering why we always end up discussing load limits.Anyway getting back on track the point here is that all the fighters above could take G-loads which would black out the pilot quite quickly
This is not surprising at the 8000 lb number. Again, to meet the 6.59 gs at loaded weight, the P-51 must be tested at an equivalent 99990 lbs of force. Dividing this by 8000 lbs, you get 12.5 gs. The 8000 lbs number is obviously a design-to number and is not meant to be any combat weight value.
These g levels are not that far off modern fighter designs where g suits are worn. These numbers are probably over design for the environment in which they fought, which is also probably why the Brits wanted to relax the P-51 specs.
Again why is it necessary to twist what I say ?? I never claimed that the tilted seat heightened footrests were better than the G-suit, just that they about cancelled out the advantage given by the early G-suit. Besides at that period exercise was the best way to withstand G-forces.
The load limit of 6.59 G's is for the P-51D at 9,700 lbs, which is with an empty fuselage tank. At 10,100 lbs with full internal fuel the load limit is 6.33 G's.
So this means that the P-51's airframe has a 9.85 G ultimate load limit at 9,700 lbs, and 9.47 G ultimate at 10,100 lbs.
This is about right for both conditions for the A,B,C,D/K with the A slightly higher with no wing tank and an Allison vs Merlin.
The early B (and RAF Mustang III) had no 85 gallon fuselage tank so these three a/c had higher ultimate Limit loads in context of amount of internal fuel to reach the same 8,000 pounds
Now as to how mouch force the airframe has to withstand, well what does this matter ?? The a/c which can withstand the most G-forces is what matters. So while the P-51 is able to withstand ~96,000 lbs of force it is also heavier than both the 109 190 and therefore has to cope with more weight for every increase in G-forces.
Again, the early pneumatic g-suits aren't much different from the ones today - I've seen both - the biggest difference is comfort and the material used.A 1 - 1.5 G improvement with the early G-suit sounds very reasonable Bill.
The pressure points, pressure itself and design of later G-suits is quit different from the early G-suits.
The tilted seat heightened footrests helped allot according to the pilots, and according to NACA a 30 degree tilt gives a huge increase in tolerable G.
From here: Physiological Effects of Positive G Forces
"The last method has not effectively been used in military aircraft to any extent to date but which is probably the system of the future. It is reclining the pilot in the cockpit.
Consider a subject sitting erect in the seat of an aircraft. The average distance from his heart to the base of the brain is 30 cm and it takes approximately 24 mm of mercury pressure to raise a column of blood 30 cm in a normal standing environment of one G. It would, of course, take the same pressure to raise a column of blood from the heart to the wrist if the wrist is held at eye level as it takes to de- liver blood to the brain.
In a study in which 250 centrifuge runs were made on human volunteers, it was demonstrated that systolic blood pressure in the radial artery held at eye level was reduced by 32 mm of mercury for every G added to the ± G2 force. Visual disturbances occurred when the systolic blood pres- sure at the base of the brain was reduced to 50 mm of mercury and complete loss of vision occurred when the pressure was reduced to 20 mm of mercury. Loss of consciousness occurred when the systolic pressure at brain level was reduced to zero. This would be equivalent to a five ± G pull, i.e., 5 x 32 = 160, where the blood pressure at the base of the brain would be reduced to zero if the systolic blood pressure in the subject was 160 at the heart level.
These forces were sustained in the study for a period of 15 seconds and the time to recovery unfortunately was not reported. It was noted, how- ever, that under a load of five G's, the systolic blood pressure was reduced by five mm of mercury and the diastolic pressure was unaffected if the head is lowered to the level of the heart. To extrapolate from that information a positive G force in itself would not produce unconsciousness or blackout if the head is lowered to heart level.
Tables 2 and 3 show the time of exposure to ± G loads when pulling from horizontal flight to vertical (Table 2) and from vertical down to vertical up (Table 3) as in an inverted humpty at various speeds from 100 to 300 MPH and at varying G loads from two G's to 12 G's. Table 1 shows blood pressure at the base of the brain with varying seat tilt angles and 0 loads up to 12 G's. Remember that L.O.C"
Soren just some more thoughts.
In most combat situations the 51 had burned away external and some internal (ie. fuse tank). The max take off weight for no stores on the A was 8200, the B/C was 9000 (with 184 wing plus internal 85 gal tank) and 9540 for D/K. The H was 8500 (with 205 wing and 50 fuse cells)
So if combat was engaged after 'drop' tanks, fuselage tank dry, but all wing fuel and ammo intact - the B was at approx 8500 and the D was at 9,000.. the H in that same conditionwas at 8100
PS the Gruenhagen discussion about 12 and 11 g ultimate load change for the lightweight design is on page 119
All fine and dandy - but still gives no indication that an angle seat will cancel out the g suit advantage. BTW the angle of the seat (which is referred as "pitch) has to be factored into the location of the flight controls. A 30 degree pitch is huge - and what Luftwaffe fighter had "pitched" seats????
And agree there - I don't know the pitch of say a P-51 or P-38 (I've sat in both). I wouldn't guess they weren't as high 25 degrees but there was a "pitch" there.FLYBOYJ,
The LW fighters have pitched seats, around 25 degrees, and the heightened footrests allowed the pilot to increase the pitch of his body even further. The raising of his legs also helps the heart push blood up to the brain.
I've seen a WW2 Berger suit, tried on Korean war vintage suits and personally own a CSU-138 that I have used on several occasions. The Berger suit I seen from what I remember was made from "canvas" (possibly something else) and rubber and seemed to have little room to get adjusted when you would put it on. The Korean War suit was very similar to a modern suit and used a nylon material - more "wiggle room' to make it easier to get on. The suit I own is around a post VietNam era suit and had all kinds of zipper and snaps that make it a little easier to put on and adjust, but from the operational standpoint they were about the same in where pressure would be placed on the legs and stomach - the biggest difference I seen from the early suit was comfort and ease of putting it on.As to the early G-suits, have you ever tried one ? Also is there a study which compares the early G-suit's effectiveness vs not wearing one ?
I think the first G suits were made in Toronto by a gent named Franks who worked under Banting(insulin guy) the RAF used the MK 1 the USAAF and RCAF the MK2 it used water instead of the modern air modelsIts interesting but if I remember correctly the first use of an anti G suit was by British Seafires in 1942. They were also used by British test pilots to help them in their analysis of new designs.
I will dig around and see what I can find.
All fine and dandy - but still gives no indication that an angle seat will cancel out the g suit advantage. BTW the angle of the seat (which is referred as "pitch) has to be factored into the location of the flight controls. A 30 degree pitch is huge - and what Luftwaffe fighter had "pitched" seats????