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Wed Jun 25, 2014, 08:48 PM

Balsamo Busted

Rob Balsamo, founder of Pilots for 9/11 "Truth", is selling a video which claims that the 757s and 767s hijacked on 9/11 were clocked at "impossible" speeds, beyond their Design Dive Velocities (Vd/Md). The video claims that the high speeds imply that the planes must not have been standard 757s and 767s, implying of course, an "inside job" conspiracy.

I posted a comment noting that the claim was nonsense because airplanes are designed to be safe at their Vd speeds, and the way the engineers would assure that is by adding a 50% margin of safety to their calculated stresses at that speed. That's because the "real-world" stresses and structural strength can only be approximated. This is a basic principle of structural engineering. Long story short, over the course of far too many posts, Balsamo claimed that's not true, that the only margin of safety for speed was between the Maximum Operating Velocity (Vmo/Mmo) and Vd. As his one and only reference for this claim, Balsamo further claims that he is "certified by the FAA to teach this material."

To settle the issue (with a source that Balsamo can't refute or denigrate), I sent the following question to the FAA:

FAR 25.301(a) says, "Strength requirements are specified in terms of
limit loads (the maximum loads to be expected in service) and ultimate
loads (limit loads multiplied by prescribed factors of safety). Unless
otherwise provided, prescribed loads are limit loads."

FAR 25.303 says, "Unless otherwise specified, a factor of safety of 1.5
must be applied to the prescribed limit load which are considered
external loads on the structure."

FAR 25.305(e) says, "The airplane must be designed to withstand any
vibration and buffeting that might occur in any likely operating
condition up to VD/MD, including stall and probable inadvertent
excursions beyond the boundaries of the buffet onset envelope."

I don't need a great deal of detail, but my question is: For stresses
caused by velocity, is there a margin of safety beyond Vd/Md (i.e. are
those considered to be limit loads or ultimate)?


Today, I received the following response (with the relevant parts emphasised by me):

Subject Re Design Loads
From Gregory.Johnson@faa.gov
To ws@#######.###
Date Today 13:58

Mr. Seger,

This correspondence is in response to your inquiry submitted to the Denver Flight Standards Office relevant to design loads. As you correctly identified in your review of 14CFR part 25, structural design loads are are identified in terms of Ultimate (Ult) and Limit loads.

Limit loads are the maximum load that it is anticipated the structure will see in service. By rule the aircraft structure must be capable of sustaining Limit loads without permanent detrimental deformation. For all loads up to Limit, deformation of the structure must not interfere with the safe operation of the aircraft. Thus consider the limit load as the operational limit.

Design loads are referred to a Ultimate loads which are bound by material properties F = P/A

Ultimate load = Limit load x a factor of safety (1.5) thus Ult. = Limit x 1.5

In design it must be assumed that while the airframe is not intended to experience loads in excess of Limit, a margin or reserve capacity is necessary to preclude structural failure thus the 1.5 factor as the boundary to define Ultimate. As the material capacity is a constant, the design (section area) is the variable to react to the applied loads and preclude structural failure. The loads then that are considered would include such loads flight maneuver, gust, torsion, delta P. From a basic loads stand point an interaction equation would be applied to address these loads. This 1.5 margin then defines the limit within which the aircraft may be assumed to safe operate within the parameters of these type of loading conditions.

An airframe is certified to a maximum velocity that is can sustain in flight and a maximum acceleration to which it can be subjected to and sustain safe flight, maneuver and landing. Each of these criteria are defined in 14CFR under Subpart C. The maximum velocity and acceleration as a design criteria are potentially the most significant considerations of a design for operation within the defined Limit load.

I hope this addresses your question

Regards.
Gregory Johnson
Denver Aircraft Certification Office
ANM100D
Phn: (303) 342-1083
E-mail: gregory.johnson@FAA.gov

We value your feedback
Aviation Safety Management System (QMS)
Customer Feedback Form:

http://www.faa.gov/about/office_org/headquaters_offices/avs/customer_feedback/air/air100/


Game over.

11 replies, 2646 views

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Replies to this discussion thread
Arrow 11 replies Author Time Post
Reply Balsamo Busted (Original post)
William Seger Jun 2014 OP
delphi72 Jun 2014 #1
William Seger Jun 2014 #10
zappaman Jun 2014 #2
johndoeX Jun 2014 #3
superbeachnut Jun 2014 #4
johndoeX Jun 2014 #5
superbeachnut Jun 2014 #7
johndoeX Jun 2014 #8
superbeachnut Jun 2014 #9
William Seger Jun 2014 #6
William Seger Jul 2014 #11

Response to William Seger (Original post)

Wed Jun 25, 2014, 09:14 PM

1. Boom

 

That is the sound of Balsamo being spanked by the FAA. Methinks the FAA should probably take a closer look at whatever certification to "teach" they gave Balsamo.

He'll huff. He'll puff. He'll obfuscate. He'll say "I told you so!" He'll point to his "list". He'll post his little diagram. He'll link to his videos. He'll invoke Kolstad or Latas or Lankford. He'll say "Oh yeah??" He'll post a response from Leslie Hazzard, the Boeing phone answerer/PR lady/aerospace engineer with the BA in Journalism as a rebuttal - no doubt something related to the top speed of a 767 at 700' being 250 miles per hour. He'll do everything but acknowledge he's as screwed up as Hogan's goat.

Stand by for more entertainment.

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Response to delphi72 (Reply #1)

Fri Jun 27, 2014, 03:11 AM

10. Unfortunately, no million-dollar prize for predicting that. (n/t)

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Response to William Seger (Original post)

Wed Jun 25, 2014, 09:25 PM

2. You believe the FAA?!?!!

Oh, Seger don't you know they are in on this?
Rob will be here shortly to set you straight!

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Response to William Seger (Original post)

Wed Jun 25, 2014, 10:42 PM

3. Once again Seger fails comprehension.

Seger,

The FAA did not say anything different to what has been explained to you by me and by FAR Part 25.

As the FAA correctly points out, "Ultimate load = Limit load x a factor of safety (1.5) thus Ult. = Limit x 1.5 "

Notice he doesn't say Ultimate "case" = Limit "case" x a factor of safety (1.5) thus .....

Nor does he say Ultimate 'speed' = limit 'speed' x factor of safety (1.5) thus...

As you have finally understood after I have repeatedly tried to explain it to you (and realizing not even Beachy is supporting your BS interpretations of FAR Part 25), Vd is not a limit load it is a speed.

Why don't you email your FAA source and ask him straight up... "is there a 1.5 margin of safety above Vd as described in FAR 25.303?"

He will tell you the same thing i have been trying to tell you. FAR 25.303 is for loads, not speed. The margin of safety for speed is between Vmo (derived from Vc) and Vd. The ultimate load (1.5 x limit load), is required up to the maximum speed (Vd).

In short, you have not proven anything but the fact you still do not understand FAR Part 25 and the three types of loads defined under 301, and regulated by 303 and 305.


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Response to johndoeX (Reply #3)

Wed Jun 25, 2014, 11:16 PM

4. oops, another Gish Gallop from pilots for truth

1.2Vd is good enough, and thus Flight 175 did not break up, as proved by video, and proved it was 175, a stock 767, on 911. Pilots for truth spread lies of impossible speeds based on the same logic used to make up 11.2g.
http://www.cesura17.net/~will/Ephemera/Sept11/Balsamo/balsamo2.html
With the logic that spawned 11.2g, the impossible speed shares the same fate; failure.

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Response to superbeachnut (Reply #4)

Wed Jun 25, 2014, 11:28 PM

5. Exactly Beachy! (sort of)

Beachy says - "1.2Vd is good enough..."

And this is the very reason Beachy will NEVER support Seger's interpretations of 25,301, 303 and 305 for margins of safety past Vd.

Unfortunately for Beachy, the 1.2VD requirement is based on "an increase of 20 percent in equivalent airspeed at both constant Mach number and constant altitude" - FAR 25.629

Were the aircraft on 9/11 remaining at a constant airspeed and altitude while lining up with their targets?

Nope...

In fact, they were well past Vd and pulling upwards of 4 - 11g's (well past the Ultimate load requirements up to Vd).

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Response to johndoeX (Reply #5)

Thu Jun 26, 2014, 02:52 PM

7. pilots for truth fail to explain "constant MACH", they can't

Unfortunately for Beachy, the 1.2VD requirement is based on "an increase of 20 percent in equivalent airspeed at both constant Mach number and constant altitude" - FAR 25.629 - johndoeX

Pilots for truth has no clue what this means, or how a plane can get to 1.2Vd without acceleration, in their fantasy world of 11.2g failed physics.

You can't explain this because pilots for truth have no qualified Aero Engineers.

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Response to superbeachnut (Reply #7)

Thu Jun 26, 2014, 03:00 PM

8. I can explain it.. and I have...

You fail to understand what has been explained to you.

Beachy, why are you having troubles understand the Federal Aviation Regulations?

Perhaps this is why?

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Response to johndoeX (Reply #8)

Thu Jun 26, 2014, 03:05 PM

9. No explanation past messing up the FAR more, on par for pilots for truth

Unfortunately for Beachy, the 1.2VD requirement is based on "an increase of 20 percent in equivalent airspeed at both constant Mach number and constant altitude" - FAR 25.629 - johndoeX


No, you can't explain this because pilots for truth do Aero the same way they do physics.


Showing everyone the wrong graphic of my post at JREF is not explaining, it is smoke screen. Why can't you explain it? How can a jet get to 1.2Vd like Flight 175?

Your impossible speed, busted by RADAR and Video, and you can't explain this to save the lie, or the fake Vg diagram.

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Response to johndoeX (Reply #3)

Thu Jun 26, 2014, 01:30 AM

6. Grade A bullshit from a B-List conspriracy huckster and fraud

From your first post to this last one, you have demonstrated that you don't understand the subject at hand well enough to even discuss it intelligently. And now, it seems you've decided that pretending to be too stupid to understand that clear FAA response is better than admitting you were wrong? Whatever; it's game over until your next scam.

Anyone who still takes you seriously hasn't been paying attention.

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Response to johndoeX (Reply #3)

Sat Jul 5, 2014, 07:58 PM

11. For the benefit of the bamboozled

> The FAA did not say anything different to what has been explained to you by me and by FAR Part 25.

> As the FAA correctly points out, "Ultimate load = Limit load x a factor of safety (1.5) thus Ult. = Limit x 1.5 "

It takes real chutzpah to claim that that's what you have "explained" to me, since it's precisely what I've been saying since my first post about your video, and which you have been trying to deny based merely on your own inability to comprehend what "load" means in this context, much less "limit load."

> Notice he doesn't say Ultimate "case" = Limit "case" x a factor of safety (1.5) thus .....

Just when I thought you might be grasping it, again you get lost with just the terminology. A "case" is a condition or situation that the designer must analyze, such as those cases specified in FAR 25.305 about withstanding vibration and buffeting at Vd/Md. The loads calculated for the limit cases are what are multiplied by 1.5.

> As you have finally understood after I have repeatedly tried to explain it to you (and realizing not even Beachy is supporting your BS interpretations of FAR Part 25), Vd is not a limit load it is a speed.

What nerve; what I actually have said is still there, Balsamo. I have never claimed that Vd is a "limit load." That is another misconception based on your own confusion about the subject matter. I have claimed that the conditions in FAR 25.305 are limit cases, so an engineer is required by FAR 25 to take the loads imposed by those conditions as limit loads, and therefore they are required to multiply those loads by 1.5 and then design a structure that should withstand those ultimate loads.

Regardless of your inability to comprehend it, Mr. Johnson unequivocally confirmed that the conditions in FAR 25.305 are limit cases, not ultimate cases, so those calculated loads -- all of them, not just flight loads -- must be multiplied by 1.5. You are simply wrong; you do not know what you're talking about even after the FAA explains it to you.

Regardless of you inability to comprehend why, the reserve strength that results from that 1.5 factor means there is an unknown margin of safety when flying beyond Vd, depending on how accurately the engineers estimated those limit loads and structural strength. You are simply wrong; you don't know what you're talking about.

You're busted.

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