1951 Pontiac Chieftain
- Hooli
- Self Appointed Internet God
- Posts: 33554
- Joined: Mon Apr 08, 2019 9:25 pm
- Has thanked: 14351 times
- Been thanked: 11129 times
- mercrocker
- Numb3rP14t3Fun
- Posts: 17070
- Joined: Fri May 17, 2019 2:53 pm
- Has thanked: 12298 times
- Been thanked: 8704 times
Re: 1951 Pontiac Chieftain
Well, hopefully not everything....
There's a great long bar in Rock & Roll heaven.......
- Hooli
- Self Appointed Internet God
- Posts: 33554
- Joined: Mon Apr 08, 2019 9:25 pm
- Has thanked: 14351 times
- Been thanked: 11129 times
Re: 1951 Pontiac Chieftain
Well the early ones had the tails fall off due to compressibility in dives.mercrocker wrote: ↑Sat Feb 13, 2021 3:52 pmWell, hopefully not everything....
p-38-lighning-in-flight.jpg.pc-adaptive.1920.medium.jpg
Private signature, do not read
- mercrocker
- Numb3rP14t3Fun
- Posts: 17070
- Joined: Fri May 17, 2019 2:53 pm
- Has thanked: 12298 times
- Been thanked: 8704 times
Re: 1951 Pontiac Chieftain
Didn't know that! Phil was right, then.
There's a great long bar in Rock & Roll heaven.......
- LynehamHerc
- Boomer, gammon, senile old fart and Eurosmasher!
- Posts: 20761
- Joined: Wed Apr 10, 2019 1:37 am
- Location: Here
- Has thanked: 13881 times
- Been thanked: 3640 times
Re: 1951 Pontiac Chieftain
There's actually a 133 page and growing P38 thread that covers this and other things on an Alternate History forum that I read.
Compressibility issues were an absolute bastard for planes of that performance, locked ailerons, reversed controls etc..
Compressibility issues were an absolute bastard for planes of that performance, locked ailerons, reversed controls etc..
- PhilA
- Posts: 2968
- Joined: Thu May 30, 2019 1:24 pm
- Location: Larose, LA, USA
- Has thanked: 934 times
- Been thanked: 6539 times
- Contact:
Re: 1951 Pontiac Chieftain
Found a leak or two. That crack goes further than I thought.
Pontac Cheepten
Plymmut Furey
Jaaaaag
Plymmut Furey
Jaaaaag
- LynehamHerc
- Boomer, gammon, senile old fart and Eurosmasher!
- Posts: 20761
- Joined: Wed Apr 10, 2019 1:37 am
- Location: Here
- Has thanked: 13881 times
- Been thanked: 3640 times
Re: 1951 Pontiac Chieftain
I just came across this.Hooli wrote: ↑Sat Feb 13, 2021 4:27 pmWell the early ones had the tails fall off due to compressibility in dives.mercrocker wrote: ↑Sat Feb 13, 2021 3:52 pmWell, hopefully not everything....
p-38-lighning-in-flight.jpg.pc-adaptive.1920.medium.jpg
It's certainly too much information but you don't have to read it:
To properly understand the compressibility problem in the P-38, one has to understand that the lockup was primarily elevators and not ailerons in that aircraft. This was another problem that aerodynamicists had trouble visualizing. There was AIRLERON lockup, but this was not a main wing problem as it was a HAMMER coming off the pilot pod on the horizontal stabilizer problem, and by hammer I mean a harmonic effect that forcefully oscillated the elevators (flutter) as the shock waves hit until pressure equalized and the control surfaces exceeded both the mechanical control forces available to move them and the tensile strength of the aircraft structure. The tail tore off and that indicated to "Kelly" Johnson, that he had the "tail control" issue. It was in the main wing spar that the "hammer" was set up, but it was definitely a tail control issue. He had to stop that hammer from forming in the first place. It was the era of "intuition", and he mentally visualized the wind flow pattern and had NACA and test pilots test for it to determine if his hunches were correct; to put numbers to the concept he imagined. My guess is that Stack beat him to the root cause, but it was Johnson who figured out where the "unstick at the upper boundary layer occurred. What I do not understand, is why Johnson missed the wing sweepback solution, which was the other way to deform the shock wave?
Sorry for the serious divergence Phil.
- Hooli
- Self Appointed Internet God
- Posts: 33554
- Joined: Mon Apr 08, 2019 9:25 pm
- Has thanked: 14351 times
- Been thanked: 11129 times
Re: 1951 Pontiac Chieftain
Interesting that they got the same issue as Typhoons with I think a different cause. The Typhoon was traced to something to do with the elevator balance weights causing tail flutter till the tail fell off.LynehamHerc wrote: ↑Tue Feb 16, 2021 10:38 amI just came across this.Hooli wrote: ↑Sat Feb 13, 2021 4:27 pmWell the early ones had the tails fall off due to compressibility in dives.mercrocker wrote: ↑Sat Feb 13, 2021 3:52 pm
Well, hopefully not everything....
p-38-lighning-in-flight.jpg.pc-adaptive.1920.medium.jpg
It's certainly too much information but you don't have to read it:
To properly understand the compressibility problem in the P-38, one has to understand that the lockup was primarily elevators and not ailerons in that aircraft. This was another problem that aerodynamicists had trouble visualizing. There was AIRLERON lockup, but this was not a main wing problem as it was a HAMMER coming off the pilot pod on the horizontal stabilizer problem, and by hammer I mean a harmonic effect that forcefully oscillated the elevators (flutter) as the shock waves hit until pressure equalized and the control surfaces exceeded both the mechanical control forces available to move them and the tensile strength of the aircraft structure. The tail tore off and that indicated to "Kelly" Johnson, that he had the "tail control" issue. It was in the main wing spar that the "hammer" was set up, but it was definitely a tail control issue. He had to stop that hammer from forming in the first place. It was the era of "intuition", and he mentally visualized the wind flow pattern and had NACA and test pilots test for it to determine if his hunches were correct; to put numbers to the concept he imagined. My guess is that Stack beat him to the root cause, but it was Johnson who figured out where the "unstick at the upper boundary layer occurred. What I do not understand, is why Johnson missed the wing sweepback solution, which was the other way to deform the shock wave?
Sorry for the serious divergence Phil.
Sorry Phil.
Private signature, do not read
- LynehamHerc
- Boomer, gammon, senile old fart and Eurosmasher!
- Posts: 20761
- Joined: Wed Apr 10, 2019 1:37 am
- Location: Here
- Has thanked: 13881 times
- Been thanked: 3640 times
Re: 1951 Pontiac Chieftain
Is it worth setting up an aircraft saddoes thread and transferring these into it?
- Hooli
- Self Appointed Internet God
- Posts: 33554
- Joined: Mon Apr 08, 2019 9:25 pm
- Has thanked: 14351 times
- Been thanked: 11129 times
Re: 1951 Pontiac Chieftain
Could be, I think we had a 'things wot fly' thread once. I'll look for it later.
Private signature, do not read