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Author Topic: Bell/NACA early studies for X-1  (Read 4314 times)

Offline hermankeil

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Re: Bell/NACA early studies for X-1
« Reply #15 on: December 15, 2017, 03:19:55 pm »
In the late 60's or early 70's, I attended a talk by Chuck Yeager at Norton AFB in which he certainly said that the X-1 had an all moving tailplane.  I know I'm old but my memory is still good.

Offline hesham

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Re: Bell/NACA early studies for X-1
« Reply #16 on: December 15, 2017, 03:22:34 pm »
In the late 60's or early 70's, I attended a talk by Chuck Yeager at Norton AFB in which he certainly said that the X-1 had an all moving tailplane.  I know I'm old but my memory is still good.

Nice Info Hermankeil.

Offline Arjen

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Re: Bell/NACA early studies for X-1
« Reply #17 on: December 16, 2017, 09:45:09 am »
For the umpteenth time the XS-1/X-1 did not have an all-moving tail, it had a conventional
horizontal stabilizer and elevator setup that could be trimmed in flight for pitch control, a different animal
from the slab tailplane and something that had been around since well before WWII.
That depends on how you look at it.

I've looked up the bit about the X-1's stabilizer in 'Yeager' by Chuck Yeager and Leo Janos. In the chapter 'Against the wall', Yeager describes how in early October 1947, on his seventh (?) powered flight in the X-1, flying at M 0.94 at 40,000ft, the elevator became wholly ineffective. After landing, flight data analysis showed a shock wave forming at the elevator's hinge point at just that speed. Jack Ridley then proposed, and I quote:
Quote
"Well, maybe Chuck can fly without using the elevator. Maybe he can get by using only the horizontal stabilizer."
The stabilizer was the winglike structure on the tail that stabilized pitch control. Bell's engineers had purposely built into them an extra control authority because they had anticipated elevator ineffectiveness caused by shock waves. This extra authority was a trim switch in the cockpit that would allow a small air motor to pivot the stabilizer up or down, creating a moving tail that could act as an auxiliary elevator by lowering or raising the airplane's nose. We were leery about trying it while flying at high speeds; instead, we set the trim on the ground and left it alone.
After thoroughly ground testing Ridley's idea, Albert Boyd agreed to trying it out in the air. Using the trim switch alone cured the control problem. The X-1 may have had a stabilizer and elevator setup, but its use as a de facto flying tail - something Bell's engineers had foreseen - enabled the X-1 to exceed M 0.94 in controlled flight.

So: intended to be used as a stablizer-elevator setup - found wanting - then used as an all-flying tail.
« Last Edit: December 16, 2017, 09:59:31 am by Arjen »

Offline taildragger

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Re: Bell/NACA early studies for X-1
« Reply #18 on: December 21, 2017, 01:04:37 am »

In almost 40 years since I first started finding traces of M.52 ancestry in the X-1 (and as alertken has said, nothing was stolen and much was shared freely) nobody has found a U.S. design that looks like the X-1 (extremely thin mid wing, bullet-shaped body, all-moving tail) that antedates the transfer of Spitfire-test and M.52-related data from RAE to NACA, and that would demonstrate independent evolution.

I don't think that any of the above demonstrates British influence.  The point about the all-moving tail has been disproven elsewhere.  The other features would part of any late 40s speed-optimized research aircraft 

Offline LowObservable

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Re: Bell/NACA early studies for X-1
« Reply #19 on: December 21, 2017, 04:39:56 am »
The other features would part of any late 40s speed-optimized research aircraft.

Not the Skystreak (low 10% wing, cylindrical body). Or the DFS 346 (swept wing, blunt nose, oval body with max cross-section level with wings). Or the X-3, or...

Added later:  Guys - I know the evidence is somewhat circumstantial and correlation ain't causation. But as Thoreau said, "some circumstantial evidence is very strong, as when you find a trout in the milk."
« Last Edit: December 22, 2017, 06:18:24 am by LowObservable »