DCS: AJS-37 Viggen Discussion

[OnlyforDCS]

Some great info in that blog. (Using google translate here). It seems that the pilot control systems gave some kind of feedback to the pilot. (Or maybe its the elevon controled delta wing). But the pilot definitely had a feedback system in the stick.

[RaXha]

Translation of the first blog post

A tough lady

 

Since I’m not yet old and experienced enough to write my memoirs I’m going to settle with writing about individual episodes that these days are relegated to the memory bank. The event in question I’m going to tell you about happened during my GFSU (Grundläggande FlygSlagsUtbildning, translates to something like ”Basic Aircraft Variant Training”).

 

We were going to practice high altitude photography with the SF-37 according to the old model that was used against targets without proper air defenses. This was the same kind of procedure that SWAFRAP (Swedish Air Force Rapid Reaction Force) was supposed to use with the AJS37 since you kept a constant semi-high altitude (~3-5000 meters, 10-16000 feet), the procedure was used when the enemy force was known to have no qualified AA defences, only AA guns, aswell as hand carried AA in the form of the SA-7 and fine caliber weapons.

 

First a few notes about the Viggens navigation systems.

 

The SF37 had a very good navigation system that was initialized very quickly. There was no need to worry about the gyros present in more modern inertial navigation systems (before GPS) had spun up. As a comparison I can point to the F111 that i had the pleasure of starting during a airshow in Denmark. From cold and dark it took 45 minutes before the pilot could start taxiing. The major part of these 45 minutes was to make sure that the navigation system was in full working order and calibrated.

 

The system was built around dead-counting using accelerometers that calculated how long you had been traveling during a specific time and in combination with doppler reading from the radar it was surprisingly accurate. Doppler didn’t work very well at altitude or over sea, so in those situations the SH37 needed a partner that could use radar to measure distances to know locations on the coast. A fun fact is that the SH37 could identify the morse code sent out by radar beacons to easier identify the beacon. In connection with the AJS modification TERNAV was also added where you could update the navigation systems further by comparing the radar altimeters measurements with previously stored radar height maps. The same principle was used in many cruise missiles.

 

During takeoff the system got two fixes, that is updates of position and course. The course was given by measuring the aircrafts heading in comparison to the take of runway direction. This was done at a certain speed just before rotation. If there was a lot of wind the recon pilots would normally fix the course just before rolling using the course on the HUD, the aircraft was aligned with the runway and then then the course fix button was pressed. This worked fairly well if taking of in singles but not as well if taking of in pairs. The position fix was given during rotation, the computer assumed that this was at the mid point of the runway, this of course gave a slight error depending on current weight of the aircraft as well as the amount of throttle given.

 

Due to the above errors a good recon pilot always had a good fix point to use to make sure the nav system was working as good as possible after takeoff, and then a few more on the way to the target area. The fix points mainly improved the accuracy of the heading readings. Before flying over the target you always wanted to have a very exact point to fix against, often the point of a headland on a lake or similar. In the winter you had to check twice since discerning a snow covered lake from a snow covered field is very difficult.

 

In this actual case we were four GFSU-trainees that were going to do high altitude photography. Out PL (flying service planner) had a very poor imagination so we were going to do the same pass four times. Two in the morning and two in the afternoon, a total of 16 flights. We started with time separation to avoid collision between the aircraft.

 

A recon flight often starts a bit hight (at about 500 meters, 1600 feet) to avoid noise in the area around the airbase. After that the altitude is gradually decreased to 100 meters (330 feet), 50 meters (160 feet) and finally 30 meters (100 feet). The reason is for the pilot to ”warm up” and to check that the navigation is working well before descending to the really low altitude. Initially you stay at a fairly low speed, usually around 500-700km/h. Thereafter you normally increase the speed gradually to Mach 0.8-0.9 and finally Mach 0.92. In the final speed the Viggen is stampeding. You can feel in the stick that the control system is working using the trimming system is working to avoid the pitch caused by parts of the aircraft closing in on supersonic flight (the centre of lift is moved from 25% of the chord in subsonic flight to 50% of the chord in supersonic flight). With regard to the environment and civilians we never enter supersonic flight over land in peace times, and over sea we always make sure there are no ships in the line of flight before going supersonic.

 

During my first flight i passed the final break before the target and was at the lowest FL and the highest speed. My navigation system was ticking down and the computer was showing me how many km i had left before i was going to climb to ensure the correct altitude over the target. I had requested clearance to climb to 10000 meters (32000 feet), a feat not always easy with regards to civilian traffic and the poor radio coverage at altitudes this low. Sometimes you had to initiate a climb at 60° and be ready to quickly abort in case the climb was denied. Just as the distance meter reached 0 and i lit zone 3 of the afterburner and pulled the stick towards me to commence my climb i saw something red swoosh below me. I didn’t think much of it and instead concentrated on keeping the correct speed and not overshooting my target altitude. At altitude i rolled over and checked the sight to ensure the target area was passing below me and let the cameras roll. I proceeded to make a few half rolls during descent and retuned to F17 (note: A Swedish airbase).

 

During my second flight i repeated the same procedure. But this time i had time to notice the red thing that swooshed by. It was the roof of a small cabin. Out maps showed roads and villages but did not always include small lone houses in the woods.

 

When us four students had finished our third pass and was commencing planning for the last one, the phone at the flight planner rang. It was an old lady that had reached out to us at F17. She said ”I like the air force very much, but you have blown the tiles of my house.” Whoops… OF course the flight planner quickly apologized and the flight path of the final flight was moved.

 

What is interesting in this story is the patience the old lady showed after this incident. She wasn’t mad or even annoyed, she just stated what had happened. Despite four very loud Viggens had past her house at less than 30 meters at speeds close to mach 0.92 with full afterburner, no less than 12 times within a few hours. Anyone who has had a Viggen pass over them at low altitude knows the pressure wave it creates, horses stamped, dogs bark, old Swedish ladies can take it until the tiles start coming of the roof.

 

*The last part is about how the old ladies are no longer as resilient and that the national tolerance for things like the airforce is very low etc, not interersting enough to translate*

Edited December 14, 2015 by RaXha

[renhanxue]

Chefsingenjören's blog is great, there are a lot of cool posts there worth reading.

 

Related to the story about blowing the roof shingles off of houses, there was an incident back in 2002 where a JA 37 actually burned and seriously hurt several people on the ground with the afterburner exhaust flame. The full investigation report is available in English, but in case you can't be bothered to read it, I'll post some choice quotes below.

 

[ame]http://www.havkom.se/assets/reports/rm2003_01e.pdf[/ame]

 

After the weather and flight briefing that was given before the flight, the guides gathered the visitors into two vehicles and drove to the end of the runway in use (runway 26) in order to watch the aircraft take off. The visitors chose to stand on a hill, which was approximately 2 meters high and 10 meters in diameter. The hill was situated 97 meters south of runway 26.

 

(...)

 

The pilot of P 11 (the leader) carried out a take off with a lit AB (zone 3). After rotation and retraction of the landing gear, the pilot turned to the left, after passing the intersection of the runways, and flew over the grass infield at a very low altitude towards the hill on which the visitors stood. The pilot passed over the hill under a weak climb with such an aircraft attitude that three persons in the group were seriously injured due primarily to the AB flame and pressure wave. Several persons threw themselves out of the way or attempted to take cover. A woman was thrown 15 meters from her original position.

 

(...)

 

The radar-measured altitude that was registered in RUF at time 1513 as 2.2 meters and the aircraft attitude was 6°. This indicates that the lowest point on the aircraft was in the interval 0–1.9 meters above the ground.

 

(...)

 

At the request of SHK, the engine manufacturer Volvo Flygmotor has submitted a report about the engine's exhaust temperatures. The report gives the exhaust temperature radially and axially behind the aircraft when the AB is lit (zone 3). Axially behind the AB exhaust nozzle the temperature is 1100 °C. The same temperature is found out to a distance of approximately ten meters behind the aircraft with a radius of about 0.5 meters, after which the temperature drops drastically. At a radial distance of 1.5 meters from the centre of the jet exhaust plume, the temperature is essentially the same as the surrounding air temperature.

If you watch the first 15-20 seconds of this video below it becomes very apparent that Volvo Flygmotor wasn't kidding - the visible part of the AB exhaust flame is almost half the length of the aircraft (which is about 16 meters long in total) and it gives the pavement a good grilling on rotation:

 

[ame]

[/ame]

 

Some great info in that blog. (Using google translate here). It seems that the pilot control systems gave some kind of feedback to the pilot. (Or maybe its the elevon controled delta wing). But the pilot definitely had a feedback system in the stick.

That's the transonic stabilization/artificial stick forces thing I was talking about earlier.

Edited December 14, 2015 by renhanxue

[OnlyforDCS]

That's the transonic stabilization/artificial stick forces thing I was talking about earlier.

 

Thanks for the clarification.

[RaXha]

First part of the second blog post:

 

At the edge of the envelope

 

Lately I have been writing a few nostalgic posts about how we used to fly in the past. At the time we had analogue aircraft that demanded more of the pilot when it comes to the actual flying. Today with system aircraft like the Gripen you have so called ”carefree maneuvering” where the aircraft itself is surveying the pilot and make sure that he doesn’t make any mistakes. This is, if course, good since it gives the pilot more capacity to handle all the new complex systems. The Gripen also has a very good user interface, enabling the pilot to do most of the tasks that on foreign machines would require both a pilot and a WSO in the rear seat (examples are F-14 A/B/D, F-15B/D/E, F-18B/D/F/G).

 

But, sometimes you’d like to do more than was is allowed.

 

In the ”good old days” the pilots sometimes flew outside of the rules. Sometimes consciously, and sometimes by mistake.

 

Since the Viggen system is no longer in use and that i have already been fired, i can in this post talk a bit about the times when i have been at the limit or even beyond the limits in a 37.

 

Low

 

Low flying has always been a Swedish specialty. Our country is unique in the way that it is large and sparsely populated. Because of this we have a rule work that allows low level flying in large parts of the country, all though in later years these areas have decreased in size more and more. The cellphone network with all of it’s masts make it more dangerous since the masts are not always where that are supposed to be according to the maps, and sometimes there are several masts where the maps just point to one mast. Masts below the height of 30 meters doesn’t need to be reported to the aviation agency. My closest contact was during a highway recon flight in a group of 4 SK60 in the light attack wing. We had clearance to go down as low as 20 meters above ground, and 10 meters above sea, but often it was even lower than that since we defined it has 20 meters assessed over ground, and the trees in Sweden are fairly high. In this case we were flying along the railway tracks between Luleå and Torneå. I was number four in the flight and all of a sudden after a turn there is a mast between me and my third. He never saw the mast that passed under his belly. I saw it clearly since it passed just above my canopy. When we checked the map later there was no mast, but it turns out that the railway company has a number of masts used for communication between railroad switches, these are of course lower than 30 meters and thus are not reported.

 

For heavier aircraft in the form of Viggen, we had clearance to fly down to 30 meters AGL, and 20 meters SGL. Earlier it was the same regulations as the light attack, but after a pilot from F15 cut the phone lines between two islands at 8 meters above the water (he was cleared of charges since 8 meters is 10 meters assessed) and was force to land with hundreds of meters of telefon wire hanging from his drop tank and body, the limits was raised by 10 meters.

 

The Viggen was harder than the SK60 to fly low with. The high speeds combined with a multitude of birds at low height meant a great deal of serious damage. A Seagul at 1000 km/h will go straight through the intake and will seriously damage the front of the canopy. You had to be careful, since turing at low altitude was dangerous and there was a big risk of the wingtips touching the ground when rolling (the wingspan was 10 meters and the roll centre was above the wings). There is a number of incidents through the years with aircraft having parts of the wing being submerged in water. Furthermore it was hard to increase the height if you were to get to low and entered ground effect, causing the nose to pitch down. A sudden nose up motion in this situation let to alpha increase, and since the rotation point was about halfway along the aircrafts length the tail can descend by several meters, the risk of the tail hitting the ground was big risk unless you were carefull.

 

My ”record” was wen i was supposed to photograph a low bridge with a SF37. Wen i closed in on the bride at Mach 0.85 i saw that it wasn’t a bridge but a culvert. The only camera that would be able to get a good shot of it was the nose camera, so instead of climbing to 100 meters i proceeded to ”descend” towards the target from 30 meters. The photo was good, but in passing the radar altimeter was indicating 0 meters (this is also visible in the photo). It isn’t entirely correct, the resolution of the radar altimeter at low altitude is 5 meters,but the foto interpreters that inspected the photo descided it was best o retire the photo the round archive (not: Swedish slang for the recycling bin)

[Kilrah]

I just love this story from the blogg previously linked to:

 

For the Viggen we had permission to fly as low as 30 meter over land and 20 meter over sea. Previously it was 20m and 10m, but after an incident where a pilot cut the phone wires between two islands (at 8 meters height) and forced to land with some hundred meters of wire hanging from the fuel tank, it was raised to the new levels.

 

Amazing story! I really hope they implement this "feature" in the game :megalol:

 

EDIT: and yes... the swedish population have become so "comfortable" and will cry and complain as soon any swedish forces are exercising. It´s really sad!

Edited December 14, 2015 by Kilrah

[QuiGon]

A huge thank you @RaXha for those translations :thumbup:

Rep inbound ;)

[BaconSarnie]

A huge thank you @RaXha for those translations :thumbup:

Rep inbound ;)

 

 

Same, also to BravoYankee4 for his translations and insights

[QuiGon]

Amazing story! I really hope they implement this "feature" in the game :megalol:

 

EDIT: and yes... the swedish population have become so "comfortable" and will cry and complain as soon any swedish forces are exercising. It´s really sad!

 

Yeah, same thing here in germany. After the end of the Cold War all low flying areas in germany have been closed :mad:

[RaXha]

A huge thank you @RaXha for those translations :thumbup:

Rep inbound ;)

 

More translation incoming! :D

[Einherjer]

Yeah, same thing here in germany. After the end of the Cold War all low flying areas in germany have been closed :mad:

 

 

Here in the black Forrest, they still fly relatively low... But I miss the sonic booms from my childhood ;)

[El Hadji]

Back in the 80's and early 90's the Swedish armed forces got away with a lot that would make headlines today. Not long ago people complained about JAS39's flying low and fast while on their way to intercept Russian Su's over Swedish waters outside Gotland. This made headlines about the outrageous behaviour of the Airforce...

 

It was different back in the days... I know about an incident in the early 90's where a Viggen pilot flew low over a friends garden party. Unfortunatly he broke the sound barrier over a farm scaring two cows to death. The farmer called the Airforce a bit upset, but they paid for the cows and the incident never even reached the media.

 

I know about another incident where a Viggen almost killed a group of part time soldiers from Hemvärnet (National Guard) when setting tree tops on fire while flying low over a forest where the soldiers had their camp. This never reached media either.

[RaXha]

Translation 2 of the second blog post:

 

High

 

To high is something i have always tried to avoid. When I was attending TIS (”Typ InflygningSkede”) learning to fly the 37 we had a session of high speed flying were the group before me for fun ended their session by rocking from 11000 meters i Mach 1.8 to a considerably higher altitude to reduce to subsonic speed. One of the students got the engine to start pumping at an estimated 18000 meters ASL (60 000 feet). For some reason the engine started again, and he should feel very lucky abut that. Without engine power the cabin pressure will quickly decrease and the blood will boil at body temperature.

 

Cabin pressure loss is one of the worst case scenario since the pilot needs to quickly dive to an altitude were the pressure is sufficient (approximately 3000 meters, 9800 feet). In addition we were not very well trained in the fact that to avoid decompression sickness, you should be breathing pure oxygen for a few minutes before climbing to high altitude. This is part of the manual for the Gripen. Because of all of this i have tried to stay below 16000 meters and have performed control flights at around 14000 meters maximum. At this altitude you can start to see the curvature of the earth and the sky goes darker as you get closer to the tropopause. It’s still a long ways of to getting a pair of astronautswings that in the US are given to those reaching altitudes in excess of 80 000 meters.

 

The J35 Draken was initially designed to meet bombers up to 30000 meters (98 000 feet), because of this there was a pressure suit that was used during trial flights. How common it was for this suit to be used in practice at the bases i don’t know. For the Viggen there never where a pressure suit, so you had to rely on the pressurized cabin, pure oxygen and the pressurized G-suit.

 

In connection with JA37 interception of the SR71 over the baltic sea there where pilots that were over 20 000 meters (65 600 feet) with the Viggen, but you have to be very careful with how you maneuver the engine. According to the emergency instructions in the pilots manual there was a risk of a ”hammershock” on the JA37, a very severe form of pumping that can cause the intakes to explode. The SR71 also had this problem and a hammershock at Mach 3 caused the aircraft to more or less disintegrate.

Edited December 14, 2015 by RaXha

[Derk]

Thank you for the translations! (rep inbound)

 

I remember hearing similar stories when i was in Arvidsjaur for arctic survival training some 13 years ago, those guys (rangers?) seemed very fond of their airforce, unlike our land forces haha. The Viggen is a childhood favourite and the swedish military have always had my greatest respect.

I am very much looking forward to the module. But more than that, it makes me want to go back.

[RaXha]

Translation 3 of blogpost 2

 

Fast

 

A Viggen is like a bumblebee. It doesn’t realize it’s limitations and flys faster than what it really should be. At about Mach 1.5 the wave resistance goes up significantly. Most aircraft designed for higher speeds have so called variable intakes where instead of a single straight shock (speed decreases from supersonic to subsonic) you get several smaller slanted shocks. (A normal jet engine can’t handle airflows at supersonic speeds, so the airflow through the engine is always subsonic). But the Viggen has one important property. The RM8 engine is massive and with a powerful afterburner the engine starts to behave like a RAM jet at high speeds. The big intakes creates a lot of resistance, but also provides the engine with a lot of air for combustion.

 

My first supersonic session in the Viggen was in the form of the so called ”motivational session” of the type training in a two seater SK37. The acceleration at low altitude between mach 0.6-0.9 with the afterburner in zone 3 is brutal and climb up to 11 000 meters is done with an altimeter that looks like the needle is about to come off.

 

During my first pass in a one seater AJ37 i was given a lesson about how much fuel the RM8A consumes with full afterburner. I was warned that the engine would consumer more fuel than the tank system could deliver and because of this the central tank could be emptied before the other tanks had a chance to top it off. Said and done i got a 24% fuel warning around Sundsvall (24% indicates the central tank is about to deplete). I throttled back and to my surprise the fuel gauge did not start to climb (like it would when the tanks refill the central tanks), but instead kept dropping.

 

I reported that i had a fault with the fuel system and started descending towards F15. I was a bit worried since the fuel gauge showed that i had less fuel than i would need to land within the proper margins. At touchdown i had only 8% left of my fuel, well below the limits of student pilots and close to where the engine could start cutting out due to air in the fuel system. The technicians measured my fuel and it appeared that the gauge was correct. How i was able to use that much fuel is to this day a mystery. According to the calculations we made afterwards i should have had well above 30% on touchdown. The only explanation would be that i had flown longer than planned.

 

Personally i have in a SF37 without cameras (just balast weights) reached Mach 1.97 in a straight flight path. The aircraft was still accelerating, but since the fuel ran out i had to abort and RTB. To dive in this case would not have helped, since the increased air density would result in a lower Mach number. To my knowledge there is no unit pilot that has reached speeds above Mach 2.0 in a Viggen. To reach higher speeds you would need energy raising climb profiles. The Finns had an interesting one with the their Mig-21 that meant climbing to 11000 meters at Mach 0.9. Then descending to reach Mach 1.1 and finally ascending to reach above Mach 2.0. To my knowledge the J35 (Draken) is the fastest aircraft ever in the Swedish Air Force. It has the same limitations as the Viggen with it’s big intakes, but compensates with a lot lower drag as long as you aren’t turning. Unfortunately i was never given the opportunity to undergo the SK35 Superstall training, but all of the 35 pilots considered it (the SK35) the turbo version of the Draken, since it didn’t have any of the heavy weapon systems.

[RaXha]

Part 4 of post 2. This is all i have time for today, time to go home! :pilotfly:

 

Slow

 

With a delta winged aircraft like the Viggen you always avoid going to slow. The risk of a superstall is big and the induced drag is very high at high AoA. Even the powerful RM8 is not enough, you need a dive to get the speed going. The combination low speed and low altitude is in other words not particularly desirable. I have because of this never exceeded the limits. But my record came in a SF37. Because of the edged nose with all of the cameras the limit of the SF37 was set at 17° AoA. in addition to this vortexes from the nose could enter the intakes and cause pumping. Pumping meant a significant loss of power and at low speed to make the problem more severe.

 

This incident happened during when i was number two in a flight. I was flying close to number one and had all my attention there as he was just meters in front of me. During a swing i felt the aircraft was very soft in the controls system. At the same time i heard ”oops” on the radio from my wingman. Exactly how much we had reached is hard to determine since the gauge stops measuring at 26° AoA. A filly initialized superstall in a Viggen starts at abut 30 alpha. Though i was flying as you say, ”in the middle of my clothes” (any other swede with a proper translation of this term is welcome to PM me! xD) and for some reason the engine never started pumping. If it did it would have been a very interesting experience to have two Viggens in a connected superstall…

 

Short

 

The shortest flight i ever flew was in a SH37 were i instantly after takeoff got a SA-06 failure (control system failure). I was very heavy with a full drop tank two jammer pods (U22+KB) on the wings. The weather was poor with rain and a low cloud base. I quickly decided to fly around the field at 100 meters and immediately land. The decision was probably not very smart in hindsight since i came in at very high speed. A failure of SA-06 meant that the steering system connected to GSA (Grund Styr Automat, Basic Steering Automation) and in because of this using the reverser was not possible in high speeds because it would cause instability. (of you look at a video of a reversing Viggen you will notice the rudder working to keep the aircraft going straight when reversing, this is not possible when SA-06 has failed). When i passed the halfway mark on the runway i was still doing 250 km/h and the brakes were not working in the heavy rain. My division buddies that was standing by the sidelines were completely convinced that i would end up in the net at the end of the runway. I was finally able to get the speed down enough to enable the reverser and stopped it within just a few meters of the end of the runway.

 

My shortest flight in a fully working Viggen was 11 minutes. The Viggen had a Pratt & Whitney JT-8D (RM8A) double stream engine that was very fuel efficient. On the other hand there was an afterburner that, if i’m not mistaken, had a fuel pump at 108 horsepower and the diameter of the fuel line to the AB was 10 cm (4 inches). Fuel consumption at full throttle was 1000 liters per minute. This was one of my last sessions at the TIS at F15. We started a flight of AJ37 and flew advanced maneuvers overhead. Start with lit AB 3 and kept the AB lit the entire flight until the gear was deployed for landing. No need to say that the student exiting number 2 after that session was very sweaty.

[OnlyforDCS]

Although I already got the gist of it through google translate still a big thanks for the efforts Raxha and a big :thumbup:

[T0x1s]

Cobra has mentioned in the past that the two unannounced aircraft that they have in development were further along in development than the F-14 is, and that they would be released by the end of the year. The last part is probably no longer true though since the announcement of the modules was planned a few months ago and Cobra being sick for a long period of time among other things has pushed it back a bit. But if they are to be believed they are a lot closer to release than the F-14. :-) :pilotfly:

 

Oh thats nice, thanks. Hope Cobra gets well soon.

 

I'm happy with it being closer than the F-14 since I love the Viggen.

 

I guess we will get our hands on it early next year maybe :)

[BravoYankee4]

Back in the 80's and early 90's the Swedish armed forces got away with a lot that would make headlines today. Not long ago people complained about JAS39's flying low and fast while on their way to intercept Russian Su's over Swedish waters outside Gotland. This made headlines about the outrageous behaviour of the Airforce...

 

It was different back in the days... I know about an incident in the early 90's where a Viggen pilot flew low over a friends garden party. Unfortunatly he broke the sound barrier over a farm scaring two cows to death. The farmer called the Airforce a bit upset, but they paid for the cows and the incident never even reached the media.

 

I know about another incident where a Viggen almost killed a group of part time soldiers from Hemvärnet (National Guard) when setting tree tops on fire while flying low over a forest where the soldiers had their camp. This never reached media either.

 

Yes, it was indeed more "cowboy style" back then, which probably ended up in better pilots and soldiers. Unfortunately that also ended up in a lot of casualties and injuries. However war is dangerous, and then most people accepted that preparing for war was also dangerous.

 

 

For many years it has been ridiculously away on the other end of the scale, which is no good either. If the situation turns ugly the armed forces and the population isn’t prepared to handle a crisis. With the last years events it is starting to swing back again, but is going slow.

 

Living in Sweden during the cold war era was for sure interesting. Myself might be a little biased (as in pro military) being a third generation in a military family. There are many stories that could be told, everything from great exercises to the polish students selling paintings (however never visiting the neighbors, just our family). And I have fond memories of Drakens and Viggens in the skies on a daily basis, and road trips that suddenly was halted temporary because of Viggens landing on a road base... :)

[RaXha]

Last part that i'm going to translate. :P

 

Long

 

RM8 is its foundation a civilian engine with a high bypass ratio. (If i’m not mistaken it was close to 1:1, meaning 50% of the air entering the intake was not part of the combustion in the engine, and instead passed straight through to the afterburner.) This has a number of advantages. It cools the engines combustion chambers, it lowers fuel consumption, and most importantly it gives a lot of extra air to the afterburner. (it also makes the engine quite resilient to bird strikes since most of the time they pass outside of the core engine.)

 

If you were careful with the throttle this meant you could be flying for a long time.

 

In the early 90s we were still performing submarine hunting. A there was that there was ”miscreant ships”, civilian ships that the enemy used and kept close to to mask their sound signature. We at reconnaissance therefore had to fly very long sessions at low altitude to hunt down these ships. WE learned that by using time economic speed instead of distance economic we could keep flying for a long time. My record is 2h30m. During one of these flights when i was flight lead we decided to keep flying for as long as possible and land with the minimum allowed fuel quantity. To avoid putting us in a bad position i contacted the flight control in Ronneby to get a weather forecast. CAOS! The weather had all of a sudden turned really bad with snow coming in over the airfield. Why no one had warned us in the air is still a riddle to me. This was a Sunday so all the other military fields were closed. In southern Sweden all of the civilian fields were closed due to the snow.

When we took off the weather forecast was good and we flew without an alternate airfield. With the help of the flight controller we decided that the closest alternate was Arlanda (Note: One of Stockholms civilian airport, about 385 km north of Ronneby). I turned my flight towards Arlanda and joked with my wingman that the 37 was tall enough to park at a gate and go do some shopping in the tax free zone.

En route to Arlanda the flight controller contacted us and informed us that Visby would be good for landing and that we could be down within 20 minutes. We turned around towards Visby, we landed and performed a quick refuel with the engine running. We took of again heading towards F17. At 90 meters AGL i saw the landing lights and could finally after 4 hours exit my 37. Without A-A refueling this was a very long session at the time. The single seater we had in the air force was the J26 (P51) Mustang that with drop tanks could keep flying for as long as the Gripen can when using AAR. Not everything is improved with new technology…

Edited December 15, 2015 by RaXha

[mattebubben]

Sorry but i just have to clarify one thing in ur translation =P.

 

Its on the last row.

 

J-26 is the Swedish Designation for the P-51.

 

J-29 would be the 1950s Jet Fighter "Tunnan"

 

a slight mixup but i just wanted to clarify =P

 

But thanks for translating for everyone who is not so fortunate as to speak the Swedish Mother Tongue ^^

[RaXha]

Sorry but i just have to clarify one thing in ur translation =P.

 

Its on the last row.

 

J-26 is the Swedish Designation for the P-51.

 

J-29 would be the 1950s Jet Fighter "Tunnan"

 

a slight mixup but i just wanted to clarify =P

 

But thanks for translating for everyone who is not so fortunate as to speak the Swedish Mother Tongue ^^

 

Of course, you are correct, fixed!

[mattebubben]

im sorry =P i did not want to be "that" guy but... xD

[RaXha]

im sorry =P i did not want to be "that" guy but... xD

 

Well I don't want to be spreading false information! :P

[mattebubben]

if you find any other good viggen posts / threads i could help with translation aswell if you dont feel like you have the time to do it all urself xD