Lockheed Martin F-22 Raptor

[sferrin]

I think you're being unfair to Ricionni about the F-22, he wrote the ATF specification so he's hardly an anti F-22 person.

I'd be interested in reading your source of that information.

 

[overscan (PaulMM)]

From James Stevenson post on skunk-works-digest

The seminal work on supercruise was done by Col. Everest Riccioni USAF
Ret. at the Northrop Corporation during the early years of the ATF
competition. He determined that fuel fraction was a critical factor in
obtaining range for a supercrusing aircraft. At the time of the ATF
competition, the range goal for the ATF was to cruise sub-sonically for
100 miles, then in 400 miles in supercruise, back out in supercruise,
and home 100 miles subsonically.

The F-22 has breached the Riccioni ideal of 0.38 as well as the minimum
acceptable fuel fraction of 0.35 due to increasing weight. Indeed, the
Air Force admits to a fuel fraction of 0.29, a figure that is bettered
by other aircraft including the F-15C, the aircraft the F-22 was
designed to replace. The F-22 does not have the fuel fraction of, for
that matter, the F8H a Navy jet that first flew in the mid-1950s.
Riccioni estimates that the F-22 at its current fuel fraction has a
supercruise range between 90-125 miles.

Riccioni was at Northrop from 1976 onwards I believe.

 

[sferrin]

Okay that's just the supercruise portion not the entire specification of which supercruise is but a part. And it doesn't sound like he wrote it but more like came up with "here is one way it can be achieved". The USAF writes the spec. companies have to meet. And if he worked for Northrop that could account for some of his bias. In the end though the USAF is more than happy with the F-22 so Riccioni and Sprey come across sounding like a case of sour grapes.

 

[Abraham Gubler]

As to rediculous procurement overspends, performance shortfalls and missed delivery dates, we all know this would be called coruption or at least incompetence in the real comercical world. If you want a prime example just look at the the Nimrod MRA4. An ungrade to an existing aircraft of 1950s design started in 1992 and still nowhere near completion. It's not just the American system that's in trouble.

In the real commercial world? There is no difference between defence procurement and civilian procurement. Except one thing. Many defence projects are for new technology development. While the MRA4 may appear to be an upgrade but it is actually the development of a brand new combat system by Boeing and the integration of new engines into an airframe. These are things that had never been done before. When the civilian commercial world indulges in new technology development they have just as much problems as defence.

If in the "commercial" world you go to Ford and say build be 10,000 F350 trucks they say no problem it will cost you $190,000 and we will have them to you next Thursday. That is because they have already built millions of these vehicles have an established production line, its simple as. To reduce it down even further this would be like you mowing your own lawn. You've done it lots of times, have all the equipment and know how big the lawn is and how long it takes.

Now if you turn to Ford and say build be an amphibious, hybrid bus and I want 10,000 of them things get a bit more complex. You can sign a contract based on everyone's best estimates of how much it will cost and how long it will take. But at the end of the day these are just predictions and when you start to do something for the first time you may find it is a lot harder (or even easier) that you thought. The same if you were told you had to go mow the lawns of Hyde Park. You might find it much harder to predict how much work it would take than doing your own lawns.

So I guess in this post-modern world where facts and knowledge are replaced by perspectives anyone can sit back in the comfort of a knowledge poor and emotionally charged point of view and call all this corruption. But in what remains of the fact based reality that some of us still cling too a little leeway and tolerance of just how hard it is to do something brand new is fair and reasonable.

 

[Abraham Gubler]

Okay that's just the supercruise portion not the entire specification of which supercruise is but a part. And it doesn't sound like he wrote it but more like came up with "here is one way it can be achieved". The USAF writes the spec. companies have to meet. And if he worked for Northrop that could account for some of his bias. In the end though the USAF is more than happy with the F-22 so Riccioni and Sprey come across sounding like a case of sour grapes.

I think you really need to understand more about the ATF program and its history to be making those kind of calls. The basic specification for the ATF was written in then 1970s outlining what USAF wanted it to be. As to the USAF being happy with the F-22, don’t believe the hype... You can learn some more:

http://pogowatercooler.org/m/dp/dp-fa22-Riccioni-03082005.pdf

 

[sferrin]

Okay that's just the supercruise portion not the entire specification of which supercruise is but a part. And it doesn't sound like he wrote it but more like came up with "here is one way it can be achieved". The USAF writes the spec. companies have to meet. And if he worked for Northrop that could account for some of his bias. In the end though the USAF is more than happy with the F-22 so Riccioni and Sprey come across sounding like a case of sour grapes.

I think you really need to understand more about the ATF program and its history to be making those kind of calls. The basic specification for the ATF was written in then 1970s outlining what USAF wanted it to be. As to the USAF being happy with the F-22, don’t believe the hype... You can learn some more:

http://pogowatercooler.org/m/dp/dp-fa22-Riccioni-03082005.pdf

POGO and Riccioni are NOT the USAF.

As for the ATF requirement *as it existed when RFPs were released* it had changed significantly from what was being toyed with in the 70's. I'd recommend the book "Advanced Tactical Fighter to F-22 Raptor: Origins of the 21st Century Air Dominance Fighter" and Jay Miller's book on the F-22. As for Ricionni and POGO's opinions I won't comment on them for Paul's sake. Suffice it to say about all they're lacking are the torches and pitchforks.

 

[Abraham Gubler]

POGO and Riccioni are NOT the USAF.

Of course but the argument put forward by Riccioni about the F-22 is a strong reason as to why the USAF received a new Chief of Staff and DepSec last year. The huge campaign (failed) put on by elements of the USAF's leadership (now purged) for the F-22s when the aircraft would have provided marginal combat power improvements and a range of other far more critical programs were allowed to implode (CSAR, MRTT, etc) was so misguided it ended in huge backlash onto USAF. While the industry that wants further F-22 work will continue to lobby for it I very much doubt we will see anything like the last few years again in its favour.

As for the ATF requirement *as it existed when RFPs were released* it had changed significantly from what was being toyed with in the 70's. I'd recommend the book "Advanced Tactical Fighter to F-22 Raptor: Origins of the 21st Century Air Dominance Fighter" and Jay Miller's book on the F-22. As for Ricionni and POGO's opinions I won't comment on them for Paul's sake. Suffice it to say about all they're lacking are the torches and pitchforks.

Well the spec can change from conception to RFP to contract to CCPs and so on. But the ATF concept from which all the specs were derived was the four point Ricionni/Boyd Fast Transient concept:

1. Extremely High Airbattle Maneuverability and Performance
2. Very High Stealth
3. A Significant Supersonic Cruise Combat Radius
4. Exceptionally Modern High-Technology Avionics to support lethality and to provide pilot awareness for survivability

This is what the F-22 was meant to be. While no. 3 has been provided for on paper an all supercruise radius of 200 NM (30 minutes) is not significant.

 

[Abraham Gubler]

"Raptor Rocks
Airspacemag Aug-Sept 2006

For their performance, which started at 2:40 p.m., Shower and Bergeson took off from Langley, 800 miles away, at about 1:25. "We were going slow," Shower says. "We were only doing about .9 Mach. Over the continental United States, there’s only a couple of places we’re allowed to go supersonic so we don’t scare everybody. But we did the math and figured we could be there if we supercruised in about 25 or 30 minutes. "

Langley AFB to Oshkosh (716 NM) in 25 minutes would require a true air speed of Mach 3 at 40,000 feet. However they could have flown 360 NM in 25 minutes at Mach 1.5. So maybe they didn't come from Langley? Which BTW is in the distance category for Dayton, Ohio (Wright-Patterson AFB) from Oskhosh (331 NM). So I suspect they got the airbase wrong.

 

[lantinian]

This link
http://www.f-16.net/f-16_forum_viewtopic-t-11567.html
seams to give some good numbers for the F119 engines.

I would like to apply some common sence maths here to get the max pure
supercruise radius of the F-22. If anyone has better data and/or math
skills, please feel free to enlighten me.

So I accept the trust levels of the F119 at full milittary power to be
2x0.8 lb of fuel per pound of trust per hour SFC. That is 100% trust
without afterburner or 2x25,000 lb of trust. At that trust we expect
the F-22 to fly at max of Mach 1,82 at 40,000+ ft.

But supercruise speed probably means flying at Mach 1,5. That speed
needs about 18% less trust and the engines SFC is 18% from max dry.
So that's about 2x21,500 lb trust, at 2x0,664 SFC to fly at Mach 1,5

If the F-22 used 20% of it's fuel to take off, accelerate to Mach 1,5,
decelerate back after the mission and land, we are left with 14,400 lb
of fuel left to spend for supercruise.

0,664 pounds of fuel per pounds of trust per hour, at 2x21,500 lb of
trust from 14,400 lb of available fuel will allow the two Raptor
engines to run for roughly 30 minutes total.

Mach 1,5 at 40,000 ft translates in about 1,600 km/h. 30 min dash at
that speed will give us a range of 800 km. Add 100 more to get to Mach
1,5 from take of and 100 back needed to land and we have a max Mach
1,5 supercruise combat radius of 500km which is about 270nm.

May not sound like much but how good will the F-15C do in the same
circumstances? It has less internal fuel and twice the SCF to keep the same speed

I Know the YF-23 would have done a lot better but that's another story.

BTW, wasn't the original requirement for about 350nm supercruise radius?

P.S. Using the figure of 20,650 lb for internal fuel, I get a 44 min of supercruise for a combat radius of 687km or 370nm.

 

[Abraham Gubler]

May not sound like much but how good will the F-15C do in the same
circumstances? It has less internal fuel and twice the SCF to keep the same speed

Yeah but no one would ever fly the F-15C on an all supersonic profile, it would cruise at transonic and accelerate to supersonic for missile launch, positioning and evasion.

Another source for calculating the supercruise endurance is the publicly released figures form USAF and Lockheed Martin. Which are a mission radius of 410 NM involving a 310 NM subsonic cruise with a 100 NM supersonic cruise. And an all subsonic cruise mission radius of 600 NM. Which aligns with Lantinian's engine SFC figures.

In contemporary conflicts an all supercruise mission is going to mean you are airborne for about 30 minutes. Talk about being tanker tied! Having to hit the tank every 30 minutes is not a good idea.

In a network centric environment with AEW&C and other broad area sensors transmitting, processing and sharing you such a strong picture of the enemy why will anyone need to cruise at such high speed?

 

[lantinian]

May not sound like much but how good will the F-15C do in the same
circumstances? It has less internal fuel and twice the SCF to keep the same speed

Yeah but no one would ever fly the F-15C on an all supersonic profile, it would cruise at transonic and accelerate to supersonic for missile launch, positioning and evasion.

I agree than full supercruise mission profile makes little operational sense, just like full VTOL fighter.

My point is this.
If the F-15C cannot measure up to one of the mission profiles the F-22 is designed to perform, why should people assume that it does better than the F-22 on the others.

F-22 has a bit more SFC than the F-15C yes, but a bit more fuel and a lot less drag on a typical configuration. It should be able to outperform the F-15C in every single scenario.
So, the hell with these fuel fractions and Col Ricconi. The truth is that when comparing just Range/Speed performance, the F-22 is a superior aircraft.

As far as I can remember the initial baseline requirement was the ATF to have 15% greater range than the F-15 on a similar mission profile. I think they have got that.

Besides, the F-15C puls only 7,5Gs right

 

[Abraham Gubler]

So, the hell with these fuel fractions and Col Ricconi. The truth is that when comparing just Range/Speed performance, the F-22 is a superior aircraft.

Yeah of course it is. But considering that this differential in range/speed is much lower than originally programmed is the F-22 improvements worth spending $70 billion on for just 180 airframes? For that money USAF could have brought over 700 brand new Super Hornets... or 70 more B-2 bombers? 70 extra B-2s all in service by 2005 if USAF had canceled F-22 in 1997? Both would be far more useful than the F-22...

 

[sferrin]

So, the hell with these fuel fractions and Col Ricconi. The truth is that when comparing just Range/Speed performance, the F-22 is a superior aircraft.

Yeah of course it is. But considering that this differential in range/speed is much lower than originally programmed is the F-22 improvements worth spending $70 billion on for just 180 airframes? For that money USAF could have brought over 700 brand new Super Hornets... or 70 more B-2 bombers? 70 extra B-2s all in service by 2005 if USAF had canceled F-22 in 1997? Both would be far more useful than the F-22...

Not in 2020 when both PAK-FA and J-XX are in service, the F-15s are falling out of the sky and so forth. If anything we should buy MORE F-22s so the investment doesn't go to waste. Better to get the required number now than to cancel it and discover in 15 years we need more and have to fund an entirely new program at even more money. Short-sightedness seems to be the national pass time these days.

 

[lantinian]

One thing I get from reading all the Books written about the F-22 ( I have have all of them) is that the F-22 is a Force Multiplyer. It increases the effectiveness all all friendly forces. So, you cannot measure its effectiveness on the battlefield without considering the operations of all friendlies involved. Ground Forces included.

No other fighter in the world at the moment has that quality. The only other aircrafts that are force multiplayers are the AWACS and other of that sort.
Flying uninterrupted high and fast with a sensor fusion, data links and big displays sounds like a mini AWAKS to me. Except that its over enemy territory and you can shoot enemy aircraft and defend yourself with the F-22 at the same time.

So, yes. The F-22 might have fallen a bit short of a few requirements along the way, but it exceeded others that did not exist untill people using it discovered they do such stuff.

I also remember one USAF general saying something like: F-22 is a lot more affordable being the best than being second best.

Another general was saiyng something like: While the F-15 works well today, the F-22 was designed to fight tomorrows battles, where its 16 times more survivable.

I think people fail to realize that yesterdays aircraft have yet to conduct combat operations against a foe armed with todays best defenses.

And to those saying the it can't fight terrorists: The F-22 is the fastest strike aircraft at service. It has the best intelligence gathering suite. It's the first platform being able to conduct a digital attack and the only one that can operate over the enemy's location without being notices. Its wing stations are yet to be utilized by the addition of stealthy pylons doubling its combat load/fuel. It's the only fighter currently in service that has enough power, cooling and space to house a fighter size laser cannon as the one being developed.

The best summary of the requirements placed upon the Raptor by the USAF is summed in just one sentence.
"It need to be twice as effective as an F-15". In my view its has far exceeded that one. So talking about F-22 not meeting its performance requirements far more pointless than talking about what else it can do besides what we already know.

 

[AeroFranz]

0,664 pounds of fuel per pounds of trust per hour, at 2x21,500 lb of trust from 14,400 lb of available fuel will allow the two Raptor
engines to run for roughly 30 minutes total.

Maybe someone can back me up on this, but 0.664 lbm/lbf/hr seems like a rather low value for the F119 SFC cruise, just based on comparison with other engines.
For example, a CFM56 (bypass ratio ~ 5), is quoted at about 0.6 lbm/lbf/hr at M0.8/35,000' and ~0.35 sealevel static (and this may be the manufacturer's uninstalled value!). With a "leaky" turbojet (bypass <1), SFC is bound to be significantly higher.

 

[overscan (PaulMM)]

Yes, it does. The EJ200 which is roughly equivalent in cycle and technology manages only a bit under 0.8 (target was 0.74, IIRC it missed it slightly).

 

[sferrin]

0,664 pounds of fuel per pounds of trust per hour, at 2x21,500 lb of
trust from 14,400 lb of available fuel will allow the two Raptor

Where do you get the 14,400 lbs of fuel from? According to Technical Order 00-105E-9 Segment 12 it's ~20,700lbs of internal fuel (3082 gallons). ??? (Yeah, I've seen the 18,500 figure too but don't know the original source of that.)

 

[lantinian]

Where do you get the 14,400 lbs of fuel from? According to Technical Order 00-105E-9 Segment 12 it's ~20,700lbs of internal fuel (3082 gallons). (Yeah, I've seen the 18,500 figure too but don't know the original source of that.)

I was using the 18,000 lb figure. However, for the purpose of being accurate I assumed the aircraft to spend 10% of its fuel for take of, acceleration to Mach 1,5 before the mission. Then after on return to use 5% for landing and 5% for emergency situation.

14,400 is 18,000 - 20%
Its the actual fuel you have available for super-cruise assuming you do not have a tanker to help you.

0.664 lbm/lbf/hr seems like a rather low value for the F119 SFC cruise, just based on comparison with other engines.

As I explained in my post, I believe the F-22 is on about 82% throttle setting when doing Mach 1,5 at 40,000 feet. SFC is bond to be at most 88% from the full dry setting of 0,8 lbm/lbf/ht, hence 0,664.

 

[Abraham Gubler]

Not in 2020 when both PAK-FA and J-XX are in service, the F-15s are falling out of the sky and so forth. If anything we should buy MORE F-22s so the investment doesn't go to waste. Better to get the required number now than to cancel it and discover in 15 years we need more and have to fund an entirely new program at even more money. Short-sightedness seems to be the national pass time these days.

The F-35s will more than deal with the PAK-FA/J-XX. If Government's were forced to buy everything for the future on worst case spec rather than accurate prediction there would be not enough money to go around.

 

[Abraham Gubler]

0,664 pounds of fuel per pounds of trust per hour, at 2x21,500 lb of
trust from 14,400 lb of available fuel will allow the two Raptor

Where do you get the 14,400 lbs of fuel from? According to Technical Order 00-105E-9 Segment 12 it's ~20,700lbs of internal fuel (3082 gallons). ??? (Yeah, I've seen the 18,500 figure too but don't know the original source of that.)

The 18,500 lbs figure is from USAF. While the fire fighting TOs say 20,700 lbs they are wrong. Most likely because a fuel tank has been deactivated - its there in the aircraft but you can't fill it with fuel but the fire fighters take note of it anyway.

 

[FrankM]

Actually, sfc @ M = 1.5 and 35-40 kft would be around 1.2 - 1.3. But then, military thrust under these conditions would only be half of the static sealevel value, so both mistakes cancel. (Data from D.P. Raymer. Aircraft Design, Appendix E, p.855)

Best regards and a happy new year,

Frank M.

 

[lantinian]

The F-35s will more than deal with the PAK-FA/J-XX.

In many ways yes, but in others....perhaps no.

There is at least one very respected author/engineer who will very much disagree with you. His name is Dr. Carlo Kopp and he's got plenty of analysis of the case for/against F-35 to justify his point of view.

I would sugest reading http://ausairpower.net/jsf.html before stating how much more "bang for the buck" is F-35 compared to F-22.

The 18,500 lbs figure is from USAF. While the fire fighting TOs say 20,700 lbs they are wrong. Most likely because a fuel tank has been deactivated

This is a very interesting speculation. Because of weight concerns the USAF deactivated/removed several of the fuel tanks so the aircraft can meet a certain performance requirements. That means if additional engine power if obtained trough upgrades, the fuel tanks can be activated/instaled.

Sort of like an internal fuel expansion slot. Very clever. I hope its true.

 

[sferrin]

Not in 2020 when both PAK-FA and J-XX are in service, the F-15s are falling out of the sky and so forth. If anything we should buy MORE F-22s so the investment doesn't go to waste. Better to get the required number now than to cancel it and discover in 15 years we need more and have to fund an entirely new program at even more money. Short-sightedness seems to be the national pass time these days.

The F-35s will more than deal with the PAK-FA/J-XX.

And that claim is based on what exactly?

 

[sferrin]

The 18,500 lbs figure is from USAF.

If it's from a public consumption document from the gov those things are mostly BS. They have the Seawolf at 800 foot diving capability and 25 knots speed. HARM at Mach 2 at 25 mile range, and so forth. I'd be far more inclined to believe a TO than a sanitized, guaranteed-not-to-get-anybody-fired doc released to the public on a government home page.

While the fire fighting TOs say 20,700 lbs they are wrong. Most likely because a fuel tank has been deactivated - its there in the aircraft but you can't fill it with fuel but the fire fighters take note of it anyway.

What source do you have that is better than a TO?

 

[lantinian]

It sais 20,650 lb here.

 

[GTX]

There is at least one very respected author/engineer who will very much disagree with you. His name is Dr. Carlo Kopp and he's got plenty of analysis of the case for/against F-35 to justify his point of view.

Some would strongly dispute this comment. Please remember that CK is extremely biased.

Regards,

Greg

 

[Abraham Gubler]

What source do you have that is better than a TO?

USAF's offical statements and those from Lockheed to Congress... There are many different types of technical orders. That people like APA cling to a TO for firefighters as the basis of their capability analysis of the F-22 is not a good idea. If the F-22 could carry 20,000 lbs of fuel it would have better range than it does now.

 

[sferrin]

What source do you have that is better than a TO?

USAF's offical statements and those from Lockheed to Congress... There are many different types of technical orders. That people like APA cling to a TO for firefighters as the basis of their capability analysis of the F-22 is not a good idea. If the F-22 could carry 20,000 lbs of fuel it would have better range than it does now.

I'd be interested in the relevant cites.

 

[Abraham Gubler]

I'd be interested in the relevant cites.

USAF Requirements Office confirming that the data on the F-22 fact sheet http://www.af.mil/factsheets/factsheet.asp?fsID=199 is correct and the Fire Fighting TO is wrong. Of course you can think this is all a conspiracy to fool the North Koreans just like the moon landing...

Fuel Capacity: Internal: 18,000 pounds (8,200 kilograms); with 2 external wing fuel tanks: 26,000 pounds (11,900 kilograms)

However the clincher is of course the publicly released radius of action figure http://www.f22-raptor.com/technology/data.html

Combat Radius (NM) Mission 1 (Sub+Super) 310+100nm

Which one hopes the F-22 can perform with 18,000 lbs of fuel rather than the more thirsty 20,000 lbs...

However if you do wish not to accept this or any of the other data released by USAF and think its all lies (which I'm sure Congress would not be so happy to hear about) then I can refer you to somewhere you may be happy:

http://worldwidewarpigs.blogspot.com/2008/10/air-force-association-takes-5th.html

In this fantasy world of F-22ism you can feel free to edit the flight envelope as you see fit.

Had to fix this one. I added the red part. The graphic is an approximation, but much closer to the aircraft's real envelope.

When you believe in something so much anything can happen...

http://www.tm.org/sidhi/conflict.html

 

[Abraham Gubler]

Is there a reason you need to be an ass about it? Is there something wrong with asking for your sources?

Don't think its an attack targeted at you. This issue (F-22s vs the World) has been so heavily coloured by misrepresentation it has actually become so ridiculous I thought a nice post summing up some of the best craziness would be appropriate.

 

[sferrin]

Is there a reason you need to be an ass about it? Is there something wrong with asking for your sources?

Don't think its an attack targeted at you. This issue (F-22s vs the World) has been so heavily coloured by misrepresentation it has actually become so ridiculous I thought a nice post summing up some of the best craziness would be appropriate.

Alright. The thing about the F-22 though is you get it on both sides of the fence. You have people claiming it's worthless because it doesn't bomb camels and others who think it's so good we only need a couple. Neither opinion of which has anything to do with planet Earth. Anyway it'd be interesting to know the circumstances around the 20,700 / 18,500 discrepancy. It'd also be interesting to know exactly why we've never seen it fly with four tanks. (It's got the hard points and plumbing for it.)

 

[overscan (PaulMM)]

I suggest we take a break and come back when there's some new actual information to discuss.

 

[flateric]

Four tanks question was discussed with one of raptor drivers at f-16.net forum - was reading this recently. F-22 has the ability, but will never fly with four tanks in his words.

 

[sferrin]

Four tanks question was discussed with one of raptor drivers at f-16.net forum - was reading this recently. F-22 has the ability, but will never fly with four tanks in his words.

I'd read on F-16.net that there was a problem. Something like the additional tanks stressed the wings more than expected but I don't know if the source was in a position to actually know or just guessing.

 

[flateric]

believe me, he's the one *in a position*

 

[sferrin]

believe me, he's the one *in a position*

Who was it?

 

[AeroFranz]

As I explained in my post, I believe the F-22 is on about 82% throttle setting when doing Mach 1,5 at 40,000 feet. SFC is bond to be at most 88% from the full dry setting of 0,8 lbm/lbf/ht, hence 0,664.

Lantinian, SFC actually gets worse when you throttle back. Gas turbine engines like running at close to maximum rpms, when you run them at less than say 75% you start seeing an increase in SFC, which gets worse and worse until it's pretty bad at idling. Unfortunately it's hard to model and strongly dependent on the cycle.
So when you fly slower, for example by throttling back to 50%, you decrease your thrust needs (good: need less fuel) but you could be increasing your SFC (bad! need more fuel). A more insightful way of thinking about speed/range performance is looking at fuel burn, which is the product of the Thrust*SFC [lbm/hr].

hope this helps

 

[donnage99]

I've seen the f-22 nozzles from its underbelly view many times, but only until today did I see this (don't know what's wrong with my eyes). It's a small tube shape right between the 2 exhaust nozzles. Does anyone know what it is and what's its function?

 

[roberto_yeager]

The stealth hook...

1Saludo

 

[flateric]

http://www.f-16.net/f-16_forum_viewtopic-t-8589.html