ARBS reduces the maximum pitch angle available.
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I'm still waiting for Ken to explain why the required fuel pressure for a mid-span fuel hose increases when an aeroplane banks.
PDR |
Beagle is correct SG is important - a change 0 0.05 in the SG figure makes a difference of 0.05 of a tonne
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Originally Posted by PDR1
(Post 10380918)
I'm still waiting for Ken to explain why the required fuel pressure for a mid-span fuel hose increases when an aeroplane banks.PDR
1. I never made such a claim. But nice try anyway. 2. If you're referencing the discussion of fuel having to move "uphill" due to dihedral and/or anhedral, the fuel system is not only designed to accommodate such features, but is designed to accommodate the worst possible unbalanced/uncoordinated bank condition (be it a slip or a skid) within the aircraft's performance envelope. Clu4U: aircraft are equipped with turn and slip/turn coordinator instruments for a reason. And if it has escaped you, the "uphill" condition created by a slip/skid far exceeds the "uphill" condition created by an/dihedral. And for the KC-10, the "uphill" condition of the tail engine far exceeds the "uphill" condition created by dihedral. Clear enough? |
Originally Posted by Just This Once...
(Post 10380915)
ARBS reduces the maximum pitch angle available.
But wait. Voyager does not have ARBS. So if ARBS is why MTOGW is reduced, why is Voyager's MTOGW reduced? Something does not add up. |
Originally Posted by Tengah Type
(Post 10380712)
BEagle
The problems at Scampton were not caused by the wing mounted AAR pods but by the ground clearance below the Underwing Fuel Tanks on the K2. The pods were head high, whereas the clearance below the tanks was only about 18 inches. So low that they were likely to hit any snow depth warning indicators next to taxiways. At Paine Field (Washinton State,USA) my Nav Rad and Crew Chief had to navigate us about 2 miles, on foot, over these as we taxied in to the parking area for an airshow. One other snag at Scampton was the "lumpy" nature of the runway construction which would have had severe consequences for the Victor fatigue life. This together with the need to remove concrete kerbs and refuelling pipes at all the dispersals was too expensive to rectify for the, then, proposed life of the Victor K2. The choice of using the wing pods or centre line HDU was also a function of the flow rate of the various receiver types. The Mk 20 pod on the Victor, which had an integral 1000lbs fuel tank, had a flow rate of 1500lbs/min whereas the HDU was 4000lbs /min. With aircraft such as the Lightning and Jaguar, which took fuel at 1100 lbs/min, it was quicker to refuel a pair on the pods rather than sequentially on the HDU. The F4 took fuel at 4000lbs/min, so would empty the pod fuel tank fairly quickly, which would not pass any more fuel until it had filled to half fuel again. Hence it was quicker to refuel a pair of F4s one at a time, with continuous fuel flow, on the HDU. The VC10 had the Mk 32 pod, which did not have an internal tank, and gave a fuel flow of 2800lbs/min, however the VC10 fuel system only allowed 2200lbs/min if both pods were in use together. The HDU was the same on both types. So, again it could be quicker to use the HDU for a pair of F4s than to use the wing pods. All of the above figures are from memory of 30+ years ago, so anybody with the reference books can challenge me without me getting upset or descending to personal abuse. |
Originally Posted by KenV
(Post 10380936)
Two comments:
1. I never made such a claim. But nice try anyway.
Originally Posted by KenV
(Post 10380126)
KC-10 has a significant dihedral. Lotsa "uphill" flow there. And besides, the plumbing and pumping is sized to provide good flow even when the tanker is flying in a bank where the "uphill" may be much more pronounced than the "uphill" provided by dihedral.
but is designed to accommodate the worst possible unbalanced/uncoordinated bank condition (be it a slip or a skid) within the aircraft's performance envelope. Clu4U: aircraft are equipped with turn and slip/turn coordinator instruments for a reason. And if it has escaped you, the "uphill" condition created by a slip/skid far exceeds the "uphill" condition created by an/dihedral. And for the KC-10, the "uphill" condition of the tail engine far exceeds the "uphill" condition created by dihedral. Clear enough? PDR |
Ken As for your claim about being the first to say anything here about the F-35's strike-dominated design: maybe you are right but in order to know that, you would have had to read the 200+ pages in the F-35 thread that were there before you joined this forum. If that is so, there are places to get help: On the HMD, you made the specific claim in 2015 that a Block IV version existed and that it had eyeball tracking. This was false, and I am aware of the source you claimed. I have met the person myself and I suspect that you misunderstood him. |
Originally Posted by BEagle
(Post 10380135)
Pressure drop and the need for higher volumetric flow rates to provide the required pod pressure for the TriStar pod programme led to the need for larger pipe bores than initially specified - getting the fuel all that way to the pod pylon wasn't very easy. Whereas the A330MRTT has the huge benefit of taking advantage of the redundant outboard engine locations of the A340 and the existing fuel feed pipework.
1. Sounds like someone screwed up twice if they had to enlarge the fuel tubes. First in under specifying the tube size to begin with, and second in not adding a jet pump down the line to up the flow and increase the head pressure to the pod. On the other hand, upsizing the tube by one standard size may be easier than adding a jet pump. 2. Consider that the A340 uses CFM56 engines. The highest thrust version used is the CFM56-5C4 @ 34,000 lbf. Fuel flow at max static thrust is about 187lb/min. (see here) For simplicity let's call it 200lb/min. Will a pipe sized to deliver 200lb/min satisfy a fuel pod that is supposed to deliver as much as 4500lb/min? I think not. So yes, having existing piping in the area of the pod is an advantage, but no, that existing piping is woefully undersized and would make the undersized Tristar pod piping problem you described above seem like child's play. The localized wing strengthening of the A330 wing to accommodate the outboard engine pylons is an advantage, but serious overkill for the much much lighter WARP that also, unlike an engine installation, generates almost no torque loads. |
Originally Posted by PDR1
(Post 10380972)
Can you show how have I misinterpretted that?
Sorry, but I still recon you're probably a Walt. |
Originally Posted by LowObservable
(Post 10380979)
Ken
As for your claim about being the first to say anything here about the F-35's strike-dominated design: maybe you are right but in order to know that, you would have had to read the 200+ pages in the F-35 thread that were there before you joined this forum. Another one taking personal potshots. Probably an effort in futility, but OK, here goes. Really? Reading every word is the only way? Fascinating claim. Are you asserting that this forum does not provide a word search for key words such as "bomber", "air to ground", "tactical strike", etc? Clu4U, with the search function one can research a subject quite thoroughly without reading every word in a thread. Further, if (a damnably big if) the subject of the F-35's air-to-ground dominated design had been previously asserted and confirmed, why would dozens of folks take such extreme umbrage with the assertion being made again? I assert that it is reasonable to assume that if a particular claim draws such deep and wide spread ire, that the claim is a new one, and not an old one. So mayhaps you should take your own advice and watch that cartoon yourself. On the HMD, you made the specific claim in 2015 that a Block IV version existed and that it had eyeball tracking. This was false, and I am aware of the source you claimed. I have met the person myself and I suspect that you misunderstood him. On the subject of Walts: you just claimed to "have met the person" yourself. If so, what is his name and how do you know him? And on the subject of schoolboy (not your subject): dredging up stuff from four years ago and then getting it wrong....yeah, pretty schoolboy. Using that four year old stuff you got wrong to justify the unjustifiable? Well below schoolboy. Try to have a nice day. Mine is wonderful, thank you. |
I just made my last reply in this thread to the various folks who made and are making personal attacks. I suspect they're attempting to get this thread shut down, and that would be a genuine shame.
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Originally Posted by KenV
(Post 10381133)
You're a PM? For both Dod and MoD programs? Sure you are!
PDR |
The TriStar fuel pipe issue came about due to someone's clever idea :rolleyes: to have an operational reason to refuel from both pods and the centreline hose simultaneously. Under such circumstances, the original pipe size would have been inadequate... Then those with a little more operational knowledge than some of the MoD advised that 3-point simultaneous prodding would be highly risky anyway and would also require the pod hoses to be extended so that all 3 receivers could keep an eye on each other. By then the whole TriStar pod issue was getting increasingly late and doubtful, plus the VC10K4 and VC10C1K would soon be entering service...
A pity that the TriStar never had pods - it would have been extremely useful with multi-hose capability and a massive fuel offload potential. All history now though. As for the F-35, I thought that it was originally seen as an F-16 / F-18 replacement, low cost (hah!) and stealthy? Which meant that it would cover all the roles of the F-16 / F-18 (and Harrier), so was never conceived as a single role fighter. That's the job of the superb F-22 - a great pity that the USAF order was curtailed. Anyway, back to tankers. How's the KC-46A going down with the end users now that they've finally got their hands on it? |
Sandiego89 # 883
The Flight Refuelling Mk 20 AAR pod was designed as an underwing store to be carried by Royal Navy aircraft such as Buccaneer, Sea Vixen and Scimitar for Buddy-Buddy refuelling. To this end it was mainly a self-contained unit, carried on a drop tank pylon, and requiring minimal input from the host aircraft. 28v DC, Air Pressure and of course a fuel supply. The Air Pressure was to pass the fuel back to the host aircraft for its own use. On the Victor the pod was filled from the main aircraft fuel system at normal Booster Pump pressure and could be isolated from the main system. The pod was normally kept full in flight to assist with wing relief (empty for Take Off and Landing). It was possible to jettison fuel (used to "Mark" to give a visible vapour trail to assist with visual RVs) or in emergency. The fuel in the pod was usually recycled with the main supply to reduce cold-soak which could be harmful to some receivers. The main motive power to the pod was provided by a Ram Air Turbine on the front of the pod. This drove the Hydraulic system which held a "Balanced Hose" during refuelling or to wind the hose in after use. The RAT also ran the internal fuel pump when passing fuel. This was controlled by the electrical system and was activated automatically by microswitches after the receiver aircraft had made contact and pushed the hose in 6-7 feet, and also switched on the Green Light. The fuel tank contained 3 Float Switches, The High Level float switch shut off the fuel supply into the pod. If the pod fuel tank emptied the Low Level float switch cut the fuel pump. When the fuel tank was half full the Mid Level float switch put the pump on again . I will add the caveat that this is all from memory. I have not operated the pod since 1971, or flown with it since 1982. My Sex and Drugs and Rock and Roll lifestyle may have impaired my memory. Mind you these days the drugs are Viagra to assist with the first part of the lifestyle, and the Rock and Roll is my gait after the obligatory nightly litre (liter) of Rose. If any ex-Victor Nav Rad has any corrections to make, feel free, I will not be upset or insult you. I will now end and let the kiddies squabble amongst themselves |
Thank you Tengah for taking the time to write up that on the MK 20 pod in #892, I do appreciate it. Good stuff to satisfy my curiosity. Did not know the F-4 could receive so much fuel that quickly- thirsty beast.
I will avoid the squabble as well. |
Tengah Type , I need to query one of your facts.
You stated that your nightly rose consumption is a litre. One litre? Surely that's an underestimate?? Hope all's well - TBs again in the Spring? |
Ken, Ken - When I start being personal you will know about it. Have I called you a poxed-up Bedlamite? A thrice-unlaundered molly-boy's codpiece? A grits-for-brains Simonist? I have not.
As for search engines: sorry, no. They are good for phrases. Lousy for meanings and intent. In a few years you'll be able to go site pprune.org "poxed-up Bedlamite" and hit this post right on the nose. Look for posts with people being mean to Ken and the results will be incomplete. Also, as I know all too well, posts commenting on the F-35 draw exactly the same response time after time. Mention its delays and someone will go "what about Typhoon and Rafale?" Drew Brugal, VSI boss for four years. Talked to him a few times. I believe, however, you may be mis-speaking or mis-remembering the sequence of events. First you said that the F-35 helmet used eyeball tracking. Then you said it was in the "Gen IV" helmet, being prepared for Block 3F. Then you admitted that you were thinking at best of a technology demonstrator. Retreating from one misleading statement to the next, like the Wehrmacht retreating from one bombed-out wreck to the next in Stalingrad. |
BEagle
More than a litre? Maybe! Sometimes it is of a darker hue. The local Bordeaux is quite palatable also. I got an email from Nic to say he is handing over the TB reins. Hope somebody else will take over, as I enjoy them when I am in country. Hope to see you there. |
Originally Posted by BEagle
(Post 10381210)
The TriStar fuel pipe issue came about due to someone's clever idea :rolleyes: to have an operational reason to refuel from both pods and the centreline hose simultaneously. Under such circumstances, the original pipe size would have been inadequate...
A pity that the TriStar never had pods - it would have been extremely useful with multi-hose capability and a massive fuel offload potential. All history now though. As for the F-35, I thought that it was originally seen as an F-16 / F-18 replacement, low cost (hah!) and stealthy? And it was always supposed to be optimized for air-to-ground while preserving air-to-air capability. It was never supposed to be the 9G turning fighter the F-16 was. F-22 was to cover the really critical air to air missions. USN took a decidedly different approach and always viewed F-35 and stealth in general as but one piece of their air power puzzle. Looks like USAF is now going down that path also They want to not only preserve their legacy non stealth F-15 fleet, they want to recapitalize them with new-build F-15Xs. Round and round we go. Anyway, back to tankers. How's the KC-46A going down with the end users now that they've finally got their hands on it? |
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