ff4life4 Posted September 22, 2014 Posted September 22, 2014 Is the Boundary Layer Control system modeled on the DCS Mig-21. The only mention in the manual of it is in the general design of the Mig 21. This system is not mentioned in the landing system. It could have a huge impact on aircraft handling if its properly simulated. If it is modeled, where are the ports exactly. And is there any specific controls for the system. Thanks Devs
Tango Posted September 22, 2014 Posted September 22, 2014 System is activated when: * Flaps landing position * Speed < 380 kph IAS It is definitely modelled - if you reduce power to idle, she drops out of the sky faster than the speed bleeds off. Best regards, Tango.
ff4life4 Posted September 22, 2014 Author Posted September 22, 2014 Thanks. Is there anyway to turn it off? Or are there no controls for it
Eldur Posted September 22, 2014 Posted September 22, 2014 There's a switch on the left side labeled "SPS" when you hover your cursor over it, right above the throttle.
stray cat Posted September 22, 2014 Posted September 22, 2014 What is the BLC for and is it by default enabled? I find my mig dropping 20m/s on landing approach with 600 IAS and the nose being level.
Corrigan Posted September 22, 2014 Posted September 22, 2014 What is the BLC for and is it by default enabled? I find my mig dropping 20m/s on landing approach with 600 IAS and the nose being level. Throttle idle? Generally: http://en.wikipedia.org/wiki/Blown_flap Win10 x64 | SSDs | i5 2500K @ 4.4 GHz | 16 GB RAM | GTX 970 | TM Warthog HOTAS | Saitek pedals | TIR5
stray cat Posted September 22, 2014 Posted September 22, 2014 (edited) Throttle idle? Generally: http://en.wikipedia.org/wiki/Blown_flap No my throttle was at 55% (on the control indicator) I have attempted a landing with the BLC switch in the down position (default is up) and the plane seemed to behave more liked I expect and the landing worked. Can someone clarify what happens when the switch is up or down and how that affects the plane descending? Edited September 22, 2014 by stray cat
Tango Posted September 22, 2014 Posted September 22, 2014 BLC system increases lift by promoting laminar flow over the wing/lifting devices. The result is that it reduces the AoA experienced by the wing, and increases lift (you can see this effect on the AoA indicator - it reduces by approximately 2 degrees in the case of the MiG-21 when the system is operating). A stall is because the air flow is disturbed, and separates from the surfaces. This flow seperation is turbulent, and adds drag as well. Best regards, Tango.
scaflight Posted September 22, 2014 Posted September 22, 2014 (edited) Stray cat: Landing in the Fishbed at 55% throttle is an excellent way to conserve fuel for the ministry of state defense - not only does your litre count go down for this approach, but you won't spend any fuel on the next trip after crashing the aircraft! :) I rarely move under 75% throttle for an approach. The Fishbed won't punish you for reaching threshold at 350-60-70 kmh, so stay fast and stay safe. =) At the rest: Should this switch be manually toggled if flaps can not be lowered or during windmilling approach (p.164 in manual)? Edited September 22, 2014 by scaflight
stray cat Posted September 23, 2014 Posted September 23, 2014 (edited) If the switch is up, does that mean the system is on or off? The tooltip is confusing. Also what other things need to be set for the system to work? Manual says: 7. Maximum permissible airspeed for going around with BLC system operating is 360 km/h. Aircraft would sink by 25 - 30 m due to automatic disconnection of BLC Edited September 23, 2014 by stray cat
Robin_Hood Posted September 23, 2014 Posted September 23, 2014 Pretty sure it is on by default, so that would tell you it's off position (also, checklists don't say to turn it on, so it's got to be on already). 2nd French Fighter Squadron
Dirty Rotten Flieger Posted September 23, 2014 Posted September 23, 2014 Yeah I think that the engine via the BLC blown flaps is giving you a lot of lift on approach. I use 75 80% throttle on approach. If you are going too fast then try using air brakes to slow down rather than throttling back.
stray cat Posted September 23, 2014 Posted September 23, 2014 But this contradicts it: 7. Maximum permissible airspeed for going around with BLC system operating is 360 km/h. Quote: Aircraft would sink by 25 - 30 m due to automatic disconnection of BLC
Luzifer Posted September 23, 2014 Posted September 23, 2014 This contradicts what? BLC is only active with flaps fully extended. If you go faster than 380 km/h, the flaps would be pushed up by aerodynamic forces which causes the BLC to turn off. To prevent that and the associated altitude loss, you must restrict speed on go around to 360 km/h.
ruddy122 Posted September 23, 2014 Posted September 23, 2014 75-80% is about right for approach in the MiG-21. While looking around the cockpit I saw that the throttle has 4 labels pertaining to the approximate throttle position. In the English Cockpit version the second to last setting says "LND" in English (not sure what it says in Cyrillic Lettering) and the approximate throttle position is around 80% Bottom line like the previous poster said before, 360-380 Kmh on final is OK, the Chute will stop you (unless you cut the chute early) in plenty of runway. The key is a proper flare attitude and wings level with minimal sink rate. Cheers [sIGPIC][/sIGPIC] LUCKY:pilotfly::joystick: Computer Specs CPU: AMD Ryzen 5 2600 6-Core 3.4 GHz| GPU: Nvidia GeForce GTX 1660 6Gb | RAM: 32 GB DDR4 @ 3000 MHz | OS: Win 10 64 bit | HD: 500 Gb SSD
ObvilionLost Posted September 24, 2014 Posted September 24, 2014 (edited) 75-80% is about right for approach in the MiG-21. While looking around the cockpit I saw that the throttle has 4 labels pertaining to the approximate throttle position. In the English Cockpit version the second to last setting says "LND" in English (not sure what it says in Cyrillic Lettering) and the approximate throttle position is around 80% Bottom line like the previous poster said before, 360-380 Kmh on final is OK, the Chute will stop you (unless you cut the chute early) in plenty of runway. The key is a proper flare attitude and wings level with minimal sink rate. Cheers In Russian cockpit that "LND" label is labeled as "СПС" - "SPS". It is strange how there is SPS switch but on throttle it's labeled as "LND". Real world manual actually mentions when landing not to go beyond BLC stop. That is if you plan to land with BLC system active and not end up as a big fireball on the runway. :) Edited September 24, 2014 by ObvilionLost [sIGPIC]http://forums.eagle.ru/signaturepics/sigpic5472_1.gif[/sIGPIC]:joystick: Win 10 | i5-6600K | 16GB DDR4 RAM | MSI Radeon RX480 | TrackIR 5 | Saitek X52 Zeus Gaming Community
Joki Posted September 24, 2014 Posted September 24, 2014 In Russian cockpit that "LND" label is labeled as "СПС" - "SPS". It is strange how there is SPS switch but on throttle it's labeled as "LND". Real world manual actually mentions when landing not to go beyond BLC stop. That is if you plan to land with BLC system active and not end up as a big fireball on the runway. :) Try flipping that SPS switch while going 350 kph will full flaps. You'll notice the difference... :)
Dirty Rotten Flieger Posted September 25, 2014 Posted September 25, 2014 Oh thanks oblivion. I wonder why they translated LND to SPS for us english speakers? Thanks for the correction
AJaromir Posted December 16, 2023 Posted December 16, 2023 Just one info missing in this necro thread. There is in detail explained how could the auto disconnection happen:
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