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For virtual pilots the question of when to ditch your drop tanks is an easy one, that’s right when you feel like it! Of course but when it comes to real world use it has never been that straight forward. So how have they been used in combat over the years? Older viewers may remember the Yankee Air Pirate team actually disabling tank jettison in some of their missions for Wings Over Vietnam to stop players dropping them ha. Quite frankly no one gave a toss about these rather mundane items until the F-35 showed up it seems when all of a sudden they became a massive burden on older generation jets with arguments going to the point of stating they couldn’t even be jettisoned! So now for a rather exciting history of some drop tank usage in combat. A bit of background Drop tank usage became common in WWII, and most will know about P-51s and P-38s on Escort over Germany with drop tanks which were jettisoned when the German fighters showed up. The need for this was to extend the range of the aircraft. [doh really] P-51 flight with drop tanks (Historylink101.com) So, couldn’t they just put more fuel internally? You may notice that tanks used in WWII were relatively small……..piston engines didn’t need that much fuel compared to jet engines. But, by the late 1950s drop tanks had become much larger because the Jet engines were getting more powerful and thus needing much more fuel. More Jet fuel means more weight and fuel is very heavy and takes up space, so if someone is designing a fighter with a set of performance requirements they often had to keep internal fuel to a minimum and put the fuel to meet the range requirement externally in drop tanks. The idea being that the pilot flies to the combat zone on drop tanks but has to jettison the tanks when performance was required. Into the Korean War era Jettisoning tanks was not always as smooth as in flight sims. May 20 1951 James Jabara was part of a 4 FIW fighter Sweep over Sinuju. As soon as MiG-15s were sighted the order came to drop tanks and Jabara punched them but only the left (Port) tank dropped. Stuck with one tank he was supposed to return to base but disregarded orders and managed to get one confirmed kill (by both sides) and damage a second despite the asymmetric control problems he must have been having. F-86 v MiG-15 over Korea (Troy White) F-105 and Vietnam era In this era dropping tanks was common but again didn’t always go without drama. “We never did figure out why they had to drop them right on top of us, and I can assure you that a 20 foot long fuel tank in the face can ruin your entire day.” (J Broughton) So wrote Jack Broughton in 1969 regarding his F-4 escorts, and in Vietnam, flights sometimes even dropped tanks just to go into the combat area clean. This also applied to some Thud drivers as well it appears although Broughton states he preferred to hang on to the tanks if he could for ResCAP. Basically in a ResCAP [Rescue CAP ] situation if the F-105 gets low on fuel they would leave the combat area to Air to Air Refuel, but it needed the tanks to get back to the combat area again for any useful period of time. If they knew they wouldn’t have to refuel again during ResCAP (e.g. getting dark) dropping the empty tanks was done anyway to increase endurance [due to the reduction in Drag and weight]. F-4s had to drop their centerline tanks at least to be able to fire AIM-7s, and ideally ensure they were flying at a speed and attitude / AoA [Angle of Attack] where the tanks didn’t hit the aircraft after jettison and ruin the pilots day! In 1973 Paul Howson fired two AIM-7E-2 Sparrows and both hit the centerline tank although luckily they didn’t penetrate it. Although he thought he had jettisoned the tanks earlier the centerline tank was still attached due to a failure. F-105D Thuds with a KC-135A (USAF) “It is hard to figure out how we can go to the Moon, yet we can’t build a fool proof system that will allow you to let go of a big blob of a tank when you want to.” (J Broughton) Picking up SAM activity the flight of Thuds dropped the tanks, but the curse of the hung drop tank affected one of the flight. The drop tanks now being bigger was a bigger problem because that one aircraft with a hung tank now needs to use a lot more fuel to keep up with the flight, or the rest of the flight needs to fly slower through the danger area! On one mission Jack discovered a failure on the 650 Gal tank that meant he couldn’t transfer fuel from the A-A tanker (KC-135) so opted to jettison it when empty on the way there. Again, getting rid of the tank when empty increased endurance enough for the mission by reducing overall drag and weight. Meanwhile over Israel Typically, Israeli pilots jettisoned the drop tanks when they were vectored towards any suspected enemy aircraft. During the Yom Kippur War this got to 50 drop tanks jettisoned per day, and they were jettisoning them even if the contact they were vectored to was false or friendly. To avoid such waste the policy was changed so they would only drop them once they had visually acquired their targets! On the 14th April 1969, Rouven Rozen had a bit of a pilot fail when he forgot to jettison the centerline tank on his Mirage IIICJ and ended up with a MiG on his tail after some rather sub-par maneuvering. Luckily the MiG pilot wasn’t so hot and he managed to pull him into a scissors and turn things around by getting behind the MiG. In another instance Iftach Spector was flying towards contacts they were vectored to on their radar which turned out to be Drop tanks that had been jettisoned by MiGs falling from the sky. IDF Mirage IIICJs (dailykos.com) The 4th Generation arrives When the F-15/16 came along they had the same design concept as the previous generation F-4s which was fly to the target on external fuel and jettison them for combat however there was one major change. The drop tanks were manufactured to a higher quality and could be used at 9G when empty. Most of the F-4 drop tanks in Nam were ferry tanks and were not really stressed for combat as such but made good canoes. This change no doubt drove up the complexity and cost of the tanks and provided more incentive for the air force to not just jettison them for the hell of it. Some of those drop tanks were converted into canoes by enterprising Vietnamese farmers (Aviationist.com) Into the Storm Now for some examples from more recent conflicts, typically they are jettisoned in emergency situations which includes any A-A engagement, flame out or SAM being fired at you. Desert Storm had its fair share of A-A and A-G action, here Jerry Oney in an F-15E taking a big risk: "Well there we were, a couple of the USAF’s finest, flying the mighty Strike Eagle at around 2000ft below a mostly scattered cloud deck in a two-mile trail at 500kts conducting a road recce for some scuds. Even then I was thinking “this isn’t the greatest idea in the history of the earth”. I was soon proved correct as we flew past this Iraqi airfield and saw the smoke trail of an SA-7, or maybe an SA-9, heading past us and towards lead. The next bit of action seemed compressed into about two seconds or less – lead broke hard into the missile in an attempt to defeat it, I watched the thing overshoot and detonate about 500ft above lead, Bill [the pilot] manoeuvred hard to avoid lead as we now had a face full of F-15E heading towards us. Damn an Eagle can turn. I felt all our ordnance come off the airplane as Bill calmly punched the jettison button as part of our attempt to avoid hitting lead and get our weight down in anticipation of another shot coming our way." F-15Cs with drop tanks (USAF) Cesar Rodriguez flying an F-15C describes one engagement with a MiG: "…so the western AWACs called on GUARD, Pop up contacts, 330 degrees for 13 miles. At 13 miles I had no option but to engage without any SA [Situational Awareness] , so I directed an in-plane turn to 330 degrees, jettisoned wing tanks and put my radar into the location of the target….." Here is another account from Rhory Dreager and Rodriguez of a different engagement in an F-15C: "We do not want to get into any turning merges if we did not have to, so we get our MiG-23 EID [Electronic ID] and AWACS clearances out of the way well before we could shoot. The MiGs were flying at 500ft, and we were flying a cut off intercept on them. At about 40 miles, AWACs told us that one of the MiGs had returned home, so we now had a radar picture of a three-aircraft “Vic” – one guy out in front and the other two guys flying behind and either side. Rodriguez added that RC-135 Rivet Joint also confirmed the EID on the MiG-23s. Dreager ordered a jettison of wing tanks to allow better maneuverability and greater speed with which to increase their WEZ." 17 Jan 1993 F-16C pilot Craig Stevenson was on a no-fly zone patrol with an F-4G over Northern Iraq when a MiG-23 started darting to the no-fly zone. As soon as AWACs had identified the MiG as hostile and called “commit” Craig jettisoned his nearly full fuel tanks but held onto his bombs. “At .95 mach I was well above the selective jettison design limitation for the fuel tanks, and the aircraft was quick to let me know. The jettison was so violent I remember looking back at my horizontal stabilizers to make sure they hadn't been damaged by the fuel tanks.” Air Force Magazine Note that even aircraft that use drop tanks do not always have to use them in combat, especially where A-A tankers are available. In Desert Storm F-16s of the 363rd FW(P) Forward deployed to King Khalid Military City AB in Saudi Arabia with A-10s meaning they could deploy with 4 x MK-84s as standard load-out with no drop tanks: USAF F-16s at KKMC during the Storm - foreground is Block 25D #84-1257 of 17TFS (USAF) Fighters without drop tanks Just to be awkward there have been a few fighters designed post Korean war that have not had the option of using Drop Tanks, these include the F-8 Crusader (non J), Su-27 Flanker, and the F-35 Lightning II. F-8 Crusader (worldwars.net) This means that when fully fueled on take off they have a much higher relative internal fuel load-out and weight because they are carrying the fuel that others carried in drop tanks. So, until the Su-27/F-35 get their fuel down to about 60% say their relative performance is significantly reduced in terms of subsonic climb, acceleration and overall turn performance. However, the lack of drag from large drop tanks will mean they can have better acceleration and higher practical speed through the transonic and supersonic regions of flight when only carrying light to no external stores. These jets also include fuel dump mechanisms that allow them to dump fuel for emergency situations such as an emergency landing. With this approach you also need a very high thrust engine to overcome the extra fuselage size, weight and drag that was put there to hold the extra fuel in the first place. Su-27 intercepts a Swedish ELINT aircaft (Swedish AF) Are drop tanks really the best way of doing things? Valid arguments against include that they take up pylon space, can cause problems if they fail, and impose performance limitations on an aircraft. Also some of the fuel in the drop tank is needed just to offset the extra weight and drag. Logistics of Drop Tanks can be an issue in terms of maintenance and getting enough to a squadron. Did any squadron ever run out of drop tanks post Korean War? [Answers on a post card because I am not aware of any on the Western side]. Cost is another thing that is brought up, it is however much cheaper to jettison the tanks rather than lose the entire aircraft and pilot. Any plus points? Rather good at extending range [duh] You can jettison them, unlike CFTs and bigger airframes. Erm….sometimes can be used to land on if they are empty and the gear fails [or you forget to lower it]: F-16C Block 25 lands on tank at Luke AFB June 17 2004 (F-16.net) The Future Seems the arguments are mute because with F-22, J-20 and Su-57 using drop tanks, and talk of some being developed for F-35 they are not going anywhere in my lifetime. Chegndu J-20 February 2017 (Elephant) Sources Thud Ridge (J.M.Broughton, 1969) Crecy Publishing James Jabara (Sherman S 2001) online Acepilots.com http://acepilots.com/korea_jabara.html Israeli Mirage and Nesher Aces (Alomi. S, 2004) Osprey Publishing F-15E Strike Eagle Units in Combat 1990-2005 (Davies.S, 2005) Osprey Publishing F-15C Eagle Units in Combat (Davies.S, 2005) Osprey Publishing USAF F-4 Phantom II MiG Killers 1972 -73 (P.Davies, 2005) Osprey Publishing Sukhoi Su-27 (Gordon.Y, 2007) Midland Publishing Title Photo credit USAF