F-22 weight growth.

Anything goes, as long as it is about the Lockheed Martin F-22 Raptor
  • Author
  • Message
Offline

zero-one

Elite 2K

Elite 2K

  • Posts: 2036
  • Joined: 23 Jul 2013, 16:19
  • Location: New Jersey

Unread post30 Mar 2019, 09:04

This is a very old article. But it is one that I see detractors use more and more often to say that the F-22 did not meet it's original design requirements.

https://www.flightglobal.com/news/artic ... eed-26820/
THE US AIR FORCE and Lockheed Martin/Boeing have agreed to allow the F-22's empty weight to increase by 610kg, or 3%, to avoid pushing costs up. The growth comprises a 385kg weight-budget increase and a further 225kg allowance for uncertainty.

The F-22's projected empty weight has increased from 13,980kg at the preliminary design-review in 1992 to 14,365kg at the critical design-review, completed in February. Programme officials are confident that the additional 225kg allowance will not be needed.

The growth is a result of design teams requesting additional weight budgets to meet requirements such as reliability, survivability and observability. The USAF says that it is "...trying to hold the line on affordability" and wants to trade weight against cost and performance.

The F-22 does not have a weight requirement. Instead, it has performance specifications. It is missing the performance targets in some areas - none of them major, Lockheed Martin maintains - as a result of the weight growth. The company is negotiating with the USAF to reduce certain performance specifications in light of the agreed weight increase.

The USAF says that a weight increase of 450kg will reduce the F-22's subsonic range by 25km (14nm) and reduce its sustained-turn performance at Mach 0.9 and 30,000ft (9,150m) by 0.08g. The service says that it is considering reducing the subsonic-range and sustained-turn performance specifications.

The F-22's Pratt & Whitney F119 engine is about 8% above its subsonic-cruise specific-fuel-consumption (SFC) specification, although it is meeting or beating its supersonic-cruise SFC target, the USAF says. Officials believe that the subsonic-cruise SFC can be reduced to below 2% above specification.

Fuel-consumption problems are highlighted in a new US General Accounting Office (GAO) report , which questions the urgency of the USAF's need for the F-22. The Congressional watchdog recommends delaying full-scale production by four to five years, until flight-testing is complete.

"The need for the F-22...is not urgent," the GAO says, recommending that production be limited to between six and eight aircraft a year until after initial operational test and evaluation (IOT&E) is completed in 2001. The report notes, that, 80 F-22s worth $12.4 billion will be on order before IOT&E is completed.

Lockheed Martin points out, that only nine of the 80 F-22s will have been completed by the end of operational testing and that approval to increase production to 36 a year, will come only shortly before the end of IOT&E, with approval for a full 48 aircraft-a-year production not planned until 2003.

Lockheed Martin's Fort Worth division has received the first titanium bulkhead for the F-22 from subcontractor Wyman-Gordon. The wing carry-through bulkhead is one of four for assembly of the centre fuselage of the first F-22, which is to begin in May.


The F-22 eventually ended up being 19,700 Kg empty. if every 450 kg in additional weight will reduce range by 14 nautical miles and sustained G at 30,000 feet, 0.9 mach by 0.08Gs then the final F-22 would have been 5,335 kg over the 14,365 kg weight limit of the critical design review and would have lost 166 nautical miles in range and 0.94Gs in sustained G turns at 30k, .9 mach.

Am I reading this correctly or is there more to this story?
Offline

quicksilver

Elite 2K

Elite 2K

  • Posts: 2529
  • Joined: 16 Feb 2011, 01:30

Unread post30 Mar 2019, 13:15

:wtf:

You trot out a nearly 25yo article and ask us ‘what’s up?’ Really??

:roll:
Offline

zero-one

Elite 2K

Elite 2K

  • Posts: 2036
  • Joined: 23 Jul 2013, 16:19
  • Location: New Jersey

Unread post30 Mar 2019, 13:42

I apologize, but I really didn't know that this happened until recently.
I was hoping someone may know what happened.

But hey a lot of people here discuss things that are way older, the YF-22 vs YF-23 thread won't die and thats 30 years old.
We go back to digging up old articles about the Mig-21 and Mig-15 for stuff to talk about. Why should this be any different?

If you're not interested, then leave the thread alone, no one is forcing you to answer.
Offline

quicksilver

Elite 2K

Elite 2K

  • Posts: 2529
  • Joined: 16 Feb 2011, 01:30

Unread post30 Mar 2019, 14:05

The point might be that it doesn’t matter unless it is somehow relevant to some operational concern today. Does anyone really care? If LM proposed the changes and the USG signed off on it/them, there were valid reasons for doing so. These kinds of decisions occur regularly in ALL aircraft development programs. You’ve been around here long enough to understand that, or at least one would think...
Last edited by quicksilver on 30 Mar 2019, 14:37, edited 1 time in total.
Offline

mixelflick

Elite 3K

Elite 3K

  • Posts: 3189
  • Joined: 20 Mar 2010, 10:26
  • Location: Parts Unknown
  • Warnings: 1

Unread post30 Mar 2019, 14:17

Sounds to me like a good reason to pursue new, higher thrust engines :)

Regardless of whether or not this kind of weight growth was rectified, the Raptor is still head and shoulders above what anyone else is flying. Despite what Sukhoi will tell you, LOL.

I would think that over time, they had the opportunity to save weight in lighter electronic warfare components, weapons and maybe even some structural parts. The trend has been toward miniaturization of the first two, and new composites could possibly reduce weight of the latter.
Offline

zero-one

Elite 2K

Elite 2K

  • Posts: 2036
  • Joined: 23 Jul 2013, 16:19
  • Location: New Jersey

Unread post30 Mar 2019, 14:30

quicksilver wrote:The point might be that it doesn’t matter unless it is somehow relevant to some operational concern today. Does anyone really care? If LM proposed the changes and the USG singed off on it/then, there were valid reasons for doing so. These kinds of decisions occur regularly in ALL aircraft development programs. You’ve been around here long enough to understand that, or at least one would think...


Thats just it. It is relevant today, not so much back in 1995. Forget the 0.9G decrease in sustained turn rate at 30,000 feet and 0.9 mach, look at the 166 nautical mile decrease in range. thats quite significant.

quicksilver, if you're not interested in this, then please leave it alone. Someone might know something about this topic, lets give that guy some room to talk.

mixelflick wrote:Regardless of whether or not this kind of weight growth was rectified, the Raptor is still head and shoulders above what anyone else is flying. Despite what Sukhoi will tell you, LOL.


Exactly, but this article tells me it was actually supposed to be a little more terrifying than what we ended up having. The
article reads"The USAF says that it is "...trying to hold the line on affordability" and wants to trade weight against cost and performance."

Looking back, the F-22 story is a bit sad, it came at a time when the need for it subsided significantly, so the USG chose to save cost by lowering some performance specs and ultimately curtailing the number of planes bought.

If only Russia or China flew 5th gens in the 90s. We could only imagine what could have been.
Offline

wrightwing

Elite 3K

Elite 3K

  • Posts: 3154
  • Joined: 23 Oct 2008, 15:22

Unread post31 Mar 2019, 01:47

How many times do we need to hear from pilots, that situational awareness/information dominance/stealth are vastly more important than any other performance metric? The Chinese and Russians aren't exempt from the laws of economics, either. Their jets will have compromises for the sake of affordability, too. F-22s are currently undergoing their MLU updates, which will shave weight off. Additionally, it's not unlikely that the ACE/AETP technology finds its way into the F-22 motors, further mitigating earlier compromises.
Offline

zero-one

Elite 2K

Elite 2K

  • Posts: 2036
  • Joined: 23 Jul 2013, 16:19
  • Location: New Jersey

Unread post31 Mar 2019, 09:16

I understand that wrightwing. I'm just interested at what happened?
Like did the DoD approve more funding to mitigate the impact of the weight growth somehow, things of that nature.
Offline

wrightwing

Elite 3K

Elite 3K

  • Posts: 3154
  • Joined: 23 Oct 2008, 15:22

Unread post31 Mar 2019, 09:36

We've never heard anyone complain about the F-22's kinematics. Worrying about hypotheticals, isn't a very productive use of one's time, especially when the "compromised" design outclasses everything in production or development.
Offline

mmm

Enthusiast

Enthusiast

  • Posts: 42
  • Joined: 30 Jul 2013, 10:58

Unread post13 Apr 2019, 13:24

In hindsight the whole "14.5t empty" thing was most likely deliberate disinformation, but that's the figure many people went by for a very long time. 5 ton, 1/3 weight growth, that's just margin of error for you I'm totally buying it. You can't be serious that it was the best internal estimate at the time, or they were actually designing around that figure. Structurally representative F-22 EMD was to fly in just 2 years. Hell even YF-22 was probably nowhere close to that figure. By contrast F-35 AA-1 didn't exceed threshold by a fraction of that and the whole JSF went back to drawing board. Also my non-existent math skill tells me by growing mass by 33% you lose about 25% G performance, that to me is a little more than 1G for a 9G fighter.

In short that was just BS number thrown around at the time to throw people off IMO. But it was kinda believable I guess, you're looking at F-15 like dimension with some internal carriage penalty.
Online

disconnectedradical

Forum Veteran

Forum Veteran

  • Posts: 678
  • Joined: 31 Dec 2010, 00:44
  • Location: San Antonio, TX

Unread post13 May 2019, 18:02

The weight in the article is probably without engines and some other equipment. When ATF engine thrust requirement increased from 30,000 lb to 35,000 lb that was because the loaded weight increased from 50,000 lb to 60,000 lb and now F-22's loaded weight is about 65,000 lb.

Also, the relationship between range and weight is not linear, it's logarithmic, so the way you're estimating is wildly off anyways.
Offline

viper12

Senior member

Senior member

  • Posts: 250
  • Joined: 28 Jun 2017, 14:58

Unread post13 May 2019, 20:16

disconnectedradical wrote:Also, the relationship between range and weight is not linear, it's logarithmic, so the way you're estimating is wildly off anyways.


*If in cruise/climb : https://en.wikipedia.org/wiki/Range_(aeronautics)#Cruise/climb
Everytime you don't tell the facts, you make Putin stronger.

Everytime you're hit by Dunning-Kruger, you make Putin stronger.
Online

disconnectedradical

Forum Veteran

Forum Veteran

  • Posts: 678
  • Joined: 31 Dec 2010, 00:44
  • Location: San Antonio, TX

Unread post13 May 2019, 20:37

viper12 wrote:
disconnectedradical wrote:Also, the relationship between range and weight is not linear, it's logarithmic, so the way you're estimating is wildly off anyways.


*If in cruise/climb : https://en.wikipedia.org/wiki/Range_(aeronautics)#Cruise/climb


Right, I forgot about steady state jet powered flight. Either way it's not linear like zero implied.
Offline

zero-one

Elite 2K

Elite 2K

  • Posts: 2036
  • Joined: 23 Jul 2013, 16:19
  • Location: New Jersey

Unread post14 May 2019, 09:06

disconnectedradical wrote:
Right, I forgot about steady state jet powered flight. Either way it's not linear like zero implied.


Thats exactly why I posted it as a question, I wasn't implying anything

zero-one wrote:Am I reading this correctly or is there more to it?

Return to General F-22A Raptor forum

Who is online

Users browsing this forum: No registered users and 4 guests