How do they work (Russian aircraft)

[JLZ]

msvgas, mig29 emergency pump is driven by fuel pressure.

What I meant is... When you compress gas you can accumulate it for later use. Compressed gas is hot and in that heat is part of it's energy. So it's very important to preserve that heat bcs you get more energy later. Link

Now, I had mentioned that oil is cooled bcs that would be indication that no accumulation of energy in hydraulics is important and that it is wasted in purpose. Basically, it is transfer media and it needs pump to be effective.

 

BTW Hydrozine will last 10-15 minutes according to info from that site (if both engines are out). I suppose it's enough to land plane in emergency?

 

 

AlphaOneSix, you are right. There are Hydraulic Accumulators in MiG29 also. One for Main and other for Boost line. These are pressurized with nitrogen at 8MPa. I think their effects last only moment bcs needed P is 2.5 times more. (and capacity of accumulators can't be big because there is only 4.5l of oil in system in first place. - wrong)

 

 

I'm sorry for my English and inability to explain things in proper manner :)

Edited August 19, 2010 by JLZ

[Rambler91]

I think that this would help: The higher pressure of a fluid, the higher boiling point is (e.g. water on pressure of 1 atmosphere has a boiling temperature of 100 degrees of celsius, but if pressure is on 2 atmosphere or, two times that of a normal outdoor pressure, boiling temperature is 120 degrees of celsius)

So, if compression pressure of an oil in hydraulic system is higher, the oil could get as much as 300-400 degrees of celsius (or more, i don't know specifics about Russian, nor US aircraft) and still retaining enough energy to convert it's energy to useful mechanic work.

[mvsgas]

msvgas, mig29 emergency pump is driven by fuel pressure.

What I meant is... When you compress gas you can accumulate it for later use. Compressed gas is hot and in that heat is part of it's energy. So it's very important to preserve that heat bcs you get more energy later. Link

Now, I had mentioned that oil is cooled bcs that would be indication that no accumulation of energy in hydraulics is important and that it is wasted in purpose. Basically, it is transfer media and it needs pump to be effective.

Got you. I understand you meaning now. I think what was confusing me is that I do not know of any other way for a dynamic or moving pressurize hydraulic system to maintain pressure without pumps, so I was having trouble understanding why temperature was being mix with pressure. Again, going back to my experience with F-16 and trying to apply and compare it to other aircraft. F-16, temperature changes affect the level of hydraulic fluid, not the pressure. Same goes for any pressurize fluid, like engine oil. Pressure is regulated my accumulator, relief valves, the pumps themselves, etc, so temperature changes do not affect pressure.

Now for the nitrogen used in the accumulator, temperature affects their pressure. I hope this makes since.

Are there aircraft out there with a hydraulic system without pumps? How does that work?

 

BTW Hydrozine will last 10-15 minutes according to info from that site (if both engines are out). I suppose it's enough to land plane in emergency?

Keep in mind the reporter on the video is a bit ignorant on what she is talking about. The emergency pump only has to worry about flight controls, everything else has more back ups. Landing gear for example can be extended pneumatically, brakes have their own set of accumulator that just sit there pressurize. If the brakes fail he can also use the tail hook to stop.

By both engine, I assume, you mean main engine and JFS or are we talking about another aircraft besides F-16?

How come Russina fighters do not have a tail hook like western aircraft, how they get the aircraft stopped without hydraulic pressure?

Edited August 19, 2010 by mvsgas

[Sov13t]

How come Russina fighters do not have a tail hook like western aircraft, how they get the aircraft stopped without hydraulic pressure?

 

Russian air force is very new to Naval Based operations. Initially VTOL was chosen to "pioneer" modern carrier ops, later Kuznetsov and SU-33s were introduced. However, shortly after the introduction of the first true Aircraft Carrier the USSR dissolved and as such put everything on halt.

 

So, naval craft are very few since there is only 1 carrier in the navy.

 

For land based ac there are drag chutes, that if I am not mistaken have their own set of back ups for proper deployment in emergencies.

[mvsgas]

I was mainly inquiring about land based aircraft, but thank you for the information about naval aircraft.

I ask because many aircraft in the US inventories past had both tail hook and drought/landing chute. F-100, F-104, F-105, F-117 etc.

[JLZ]

Good that you've understood. I always make my explanations complicated. In foreign language it isn't easier too.

 

F-16? I thought we were talking about F-15 (although nobody have mentioned it) :megalol:

 

Concept works. Good. Reporter is hilarious :D (pilot heavy breaths... he put effort to keep aircraft nose up...)

 

Landing gear system is actuated by hydraulic. Emergency LG is pneumatic with backup compressed air containers.

 

Brake system is pneumatic. Emergency Brake system is also pneumatic (2nd line).

 

Sov13t explanation might be correct one. I thought that 'trap landing' requires stronger airframe to maintain structural unity and that mean more cost and that lower number of aircraft and the chutes are cheaper).

 

Drag chutes also have installed backup canister of compressed air.

[mvsgas]

Well the F-16 wouldn't "Trap" on the runway like navy aircraft do on the carrier. Normally arresting gear on USAF bases are place opposite side from approach/landing runway.

If an F-16 would attempt to "trap" would look like this

http://www.f-16.net/gallery_item15616.html

Just my guess.

 

Anyway, what about SU-25, anybody know how do they operate? We have great insight into the MIG-29 thanks to the manual. What about other aircraft? How are they different or similar?

 

Thanks for the conversation guys :thumbup:

[Case]

Anyway, what about SU-25, anybody know how do they operate? We have great insight into the MIG-29 thanks to the manual. What about other aircraft? How are they different or similar?

Geier started this thread a while back. I do not read Russian, but perhaps some of our Russian friends can dig out some information.

 

But great initiative mvsgas, very interesting thread!

[mvsgas]

Thanks Case

 

Could any of you guys maybe start the same thread in the Russian side of the Forums?

I could use one of the online translator, but I'm sure it would confuse meaning more than anything. I can read Cyrillic but do not understand it ( except for simple words and sentences; Gde Vodka? где водка? gde gastinitsa где гостиница?, you get the picture )

[mikoyan]

here is a fantastic video for this discussion:

mig-23 walk around!

 

 

[Krippz]

here is a fantastic video for this discussion:

mig-23 walk around!

 

 

 

Great find. Thanks for posting!:thumbup:

[JLZ]

Mikoyan, excellent finding.

 

More their videos: Coldwarair's Channel

 

Cold War Air Museum Web-site

 

If you check their blog you'll see they have SR-71 simulator (not yet operational, though)

[mvsgas]

Thanks guys

[JLZ]

Are there aircraft out there with a hydraulic system without pumps? How does that work?

 

I don't know for aviation but on the ground, instead of hydraulics pump you could use vacuum booster.

We have one in the car that assists braking.

[mvsgas]

I do not think they can use that type of system on supersonic fighter aircraft. I have been looking around the net see if I can find more info.

http://www.allstar.fiu.edu/aero/hydraulics.htm

I just started reading some of this sites, but, the reason is that type of system I do not think can produce enough pressure. For example, if I converted the pressure on the MIG-29 manual correctly, MIG-29 uses around 2600 PSI for its hydraulic systems. All other aircraft I have worked on have very high pressure systems as well. I will read more and come back later.

Thank for the info tho

[JLZ]

You are right. From link that you had provided, at very end of chapter it said:

• It requires a very large booster stroke to meet the requirement
  

If a 3 inch piston stroke is needed from the actuating cylinder moving the control surface, then the total volume of fluid moved by the actuating piston's movement is stroke x piston area = (3 inches) x (10 square inches) = 30 cubic inches

This is the volume of fluid that must move out of the booster to the actuating cylinder. Thus the smaller piston in the booster must stroke a distance equal to the volume of fluid needed divided by the piston area = (30 cu. in.) / (1/2 sq. in.) = 60 inches = 5 feet!

 

• Pressure Boosters must be built into the aircraft during the aircraft's construction, if high pressure is needed in the hydraulic system.
  
• Weight of the pressure booster is high if it is put into the aircraft, thereby reducing payload aircraft can carry.
  
• Leakage from the pressure booster is an important factor and will increase possibility of fire hazards.
  

 

Good to know, thanks

[mikoyan]

Watching the mig-23 video can we speculate that the su-27 also uses compressed air to open the cockpit?

Is there anyway we can find the su-27 translated to English ?

About the cold war museum, they need to get a hold on a mig-25! also can we find the mig-25 manual?

Now look at that afterburner!

[Sov13t]

Watching the mig-23 video can we speculate that the su-27 also uses compressed air to open the cockpit?

 

Nitrogen is used in all of the Russian aircraft to open/close the canopy besides the manual ones of course. Not compressed air.

Edited August 20, 2010 by Sov13t

[zakobi]

Watching the mig-23 video can we speculate that the su-27 also uses compressed air to open the cockpit?

Is there anyway we can find the su-27 translated to English ?

About the cold war museum, they need to get a hold on a mig-25! also can we find the mig-25 manual?

Now look at that afterburner!

 

Didn't knew there was a private owned one... On another hand, am I the only one seeing some similarity between this two-seaters front section and the f-4 front section?

[mvsgas]

So far I think we got more questions than answers :D I like tho

I wonder why did they choose to use pneumatics on so many different systems? (Cockpit, brakes, etc) F-15 uses hydraulic accumulators for their canopy, F-16 and F-117 are electrical motors.

[Krippz]

So far I think we got more questions than answers :D I like tho

I wonder why did they choose to use pneumatics on so many different systems? (Cockpit, brakes, etc) F-15 uses hydraulic accumulators for their canopy, F-16 and F-117 are electrical motors.

 

Are the use of pneumatics cheaper and more flexible than using hydraulic accumlators?

[mvsgas]

Depends, I have not finished reading the MIG-29 manual. If they are self generating, meaning the aircraft refills the pressurize pneumatic reservoirs, yes it would be cheaper. Also you got lees chance of a fire. ( Hydraulic fluid has a high flash point but it can still burn) Also you do not have to worry about Hazardous Materials (HAZMAT) The storage and disposal add to the cost and logistics.

 

You have good point it is cheaper, cool.

[JLZ]

Nitrogen is used in all of the Russian aircraft to open/close the canopy besides the manual ones of course. Not compressed air.

 

I've mentioned compressed air before in posts but it was high pressure nitrogen. I saw 'System filler' and assumed it was part of aircraft accessories but it was connection point?!

Sorry about that...

 

Su-27 also uses high-pressure nitrogen for canopy operation and sealing.

[mvsgas]

Some thing else I was wondering about is weapons separation. For example for us, bombs are thrown away from the aircraft and missiles just slide off the rails, except for airframe mounted missiles (i.e. F-4, F-14, F-15, F-18) that are also thrown away from the aircrfat.

 

How are weapons release from an SU-25?

[mig29movt]

Depends, I have not finished reading the MIG-29 manual. If they are self generating, meaning the aircraft refills the pressurize pneumatic reservoirs, yes it would be cheaper. Also you got lees chance of a fire. ( Hydraulic fluid has a high flash point but it can still burn) Also you do not have to worry about Hazardous Materials (HAZMAT) The storage and disposal add to the cost and logistics.

 

You have good point it is cheaper, cool.

 

It's less complicated (read: cheaper) also because you can release air where and whenever you wan't into the atmosphere but you need a closed circuit with a tank when you're using oil. Also air is always avalaible and compresses itself at high speeds/temperatures (e.g. Ramjet).

 

But I don't get it why they're using Nitrogen...

 

Note: If you're using Win7, you can use your calculator to convert pressure, lentgh... units (win-key+r, type calc and hit enter, switch it to "scientific" via the view menu)