jonboede

I think any gamer here could be taught to solo the real thing in 5-7 hours if they studied hard and fully loaded the dash-1 in their heads. But taxiing for style points... that... THAT takes a lot of hours of practice.

Easy to full-stick the real aircraft, just at really low airspeeds, just have to have low G loading. My favorite thing was to take airline pilots up and ask them, "If stall speed is proportional to the square root of G load, what's the stall speed at zero G?" This would momentarily fry their minds but most would say, "I guess it's zero?" I would take a strong upline when doing this and push the nose over at the top to almost completely unload it and then roll the airplane around smoothly at 30 KIAS while going through the top of the ballistic arc. Did it beautifully. Both hands on the stick, tho' for when the control surfaces start to grab some air again. The L-39 loves to snatch the stick when it's flopping around.

I read the other thread and I concur that this airplane stalls WAY too easily compared to the real thing. Might just be that I have far more ability to over-control the aircraft because a joystick is basically fly-by-wire, but it still doesn't feel at all like the real thing. This goes back to my statement that none of the planes in DCS seem to have any "weight" or "momentum" to them... they prance around far too much for something that weighs 10,000 lbs and has (literally) tons of air flowing over them.

Cockpit noise... at 0:15 you can hear me say something even though I'm in the front and the camera is in the back. Also, conversations in the last 30 seconds. https://www.facebook.com/jon.boede/videos/vb.1167655370/10203697574537700/?type=3

Just a few things I've noticed that don't feel right to me in the Albatros: 1. L-39s are never left on the ramp with the flaps down and gear doors open. The only time I have seen this is with L-39s that have been sitting out to rot for years on Kharkov air base in the early 2000s (probably so that they can be inspected to make sure no small creatures were making a home in the gear wells -- but even then, flaps were in the up position). The doors are latched and will not "bleed down" over time, even with zero hydraulic pressure in the main and emergency systems. In operational situations the aircraft are always doors closed, flaps up. In order to get the gear doors open when the gear are down, you have to pull the emergency gear lever (when pressure is still in the system), which you will see is not a procedure in the checklist. I checked with my friend who was in charge of the East German L-39s and he said no, never are gear doors left in this condition. Also, flaps in the up position. Leave the flaps down after parking and guess who's buying the beer? 2. When sealing the canopy there there is a slight hissing sound as you go through the middle of sliding the seal/air-conditioning lever. Over about 5 seconds the outside noise is gradually reduced as the canopy seals come to full inflation. The current sound level in the cockpit sounds like an unsealed canopy. I would say the sound gets cut by at least 1/3, almost 1/2 of the current noise level after the canopy seals. The L-39 is a very quiet aircraft. When the person in the rear seat records a flight with a handheld camera, you can almost make out their normal conversations on the video. If they're shouting something like "oh sh!t!" it's perfectly clear over the engine noise. It takes a long time for the air conditioning valve to open, so there's a sequence of hissing, then noise reduction, then the conditioner emergency C&W light going off that has a certain "feel" to it. In the sim, you just move the lever and wait a long time... in the real plane there are these other things going on and so it feels like it takes less time even though it still takes forever for the a/c bleed valve to open. 3. When the flaps finish moving into the selected position, there is a very positive, satisfying GLUNK noise that comes from deep within the aircraft body. This is the sound of the electrohydraulic valve closing to discontinue flow of the hydraulic fluid to the flap actuators. This is most noticeable at low RPMs of idle or during taxi. The combination of the GLUNK at the same time the selector switch pops back to your finger provides very nice feedback that the aircraft is in the configuration you asked for. 4. One of the things that would be nice is: instead of hitting RALT+HOME to put the throttle in the idle position, sliding the throttle up and back would put it in the idle position. In the real airplane the recommended procedure is to quickly and smoothly move the throttle from stop to nearly all the way forward and then back to the idle position (where the lockout prevents it from being moved to the stop position). There is some slop in the throttle linkages and coming back to idle instead of going forward to idle apparently is the better way to do it. Jan Vlček's son, Václav told me this and he was an "engine guy" at the Aero factory, so I take it as gospel. Plus, I'd rather move the throttle than some key combination. 5. I don't know about all the failure modes that are modeled in the sim, but one that is common is that the "music box" that sequences the start looks for oil pressure in the safir at 30 seconds after the turbo button is pushed. If it doesn't get the oil pressure (because a small filter likes to get clogged), it cuts the starter. If a pilot doesn't wait until after the 30 second mark in the start to push the main engine button there is a danger of fuel and spark being introduced to the engine just at the time the air starter is dropping out. Can be very bad. This is one of the many reasons the stopwatch should be clicked for both the turbo and the main engine start. 6. My only other observation is that "momentum" doesn't seem to be modeled too well in any of the aircraft in the sim. The L-39 flies right at all the numbers but doesn't "feel" like a 10,000lb aircraft. In the real aircraft you can grab the stick and "stir the pot" by making a circle 9" in diameter in a 1/2 second and the airplane doesn't move much, it just wobbles slightly. In the sim, aircraft are properly responsive, but they don't feel like they have "weight" to me. Otherwise, this is an almost perfectly modeled L-39 sim. Feels and looks like starting and flying the real thing!

Like the L-29, the shortest takeoff in the L-39 can be made by over-rotating and "hopping" the airplane up in to ground effect then allowing it to accelerate. This is done with a sharp stick pull-push but great care must be taken not to get too far off the ground or to maintain too much AoA or the airplane will mush back to the ground.

I'd like to try this as well. Need to get a comm headset. Both front seat and back seat... I have 400+ hours in the real L-39 and never did have the guts to try flying the "drunk pilot routine" -- it's much harder than it looks! [ame] [/ame] For style points, learn to do a touch and go never letting the nose wheel touch.

When the canopy is sealed / air conditioning is turned on in a real L-39 the cockpit is much, MUCH quieter than in the sim. Especially in a good helmet. In videos we made the guy in the back seat is talking while he's making the video and you can almost hear what he's saying. If he's talking loudly you can definitely hear what he's saying (usually, "holy! shiiiiit!")

Here is the checklist I used for my L-39ZA. Note airspeed is in knots, altitude is in feet. L-39ZA Checklist.pdf

Note he is wearing ZSh-5 not ZSh-7. Nice contrails... the tip tanks on the L-39 put out beautiful coils of contrails when the weather is just right.

This is why you turn it on at 2,000 meters. But with pressurization system no problem flying even above 6,000 meters because the cabin altitude is quite low. System failure? This system is almost too simple to fail. Besides, it's a trainer... if something isn't working, go back to base and have lunch.

Oxygen on/off is done going through 2,000 meters. The cabin is pressurized... leave oxygen off unless you're going above 4,000 meters (probably even 5,000 meters).

Agreed. No shaking at all when flaps are extended. There is a minor pitch change. And it only needs to be re-trimmed because you're slowing down, not because of the flaps.

My friend who's flown both says, "The L-39 is an underpowered Hawk". They're almost the same plane excepting for the fact that the Hawk makes much, much more smash. He does allow that the L-39 has a roomier cockpit. The only thing you'd want to fight with the L-39 is another L-39. If he had to chose an airplane to own, L-39 all the way... $$$$.

Engine in the sim runs too hot. On start it should go to about 450 + OAT. If I see over 520 on start, I am pulling the throttle off. Because if it goes above that it's going to keep going and then it's time to empty the fire bottle and go have some beers. At max power it should be 580 + OAT. The engine in the videos so far shows higher than that. Maybe that's why it smokes so much. :-) The overhaul facility would be very happy to $ell you a new engine. Very, very happy.

Braking is proportional to pedal displacement, but nobody does it this way IRL. Instead, full rudder input left or right, and modulate the amount of turn with the amount of pressure on the brake lever. A series of small squeezes on the brake lever gets the best result. You would be flying solo in a real L-39 with 5-7 hours of instruction. To taxi it for style points requires at least another 15-20 hours of practice. :-) Keep speed above a walking pace and this makes it easier. The Russian system is superior in some ways. Since the nose wheel is not connected to the tail you can use the crowning of a taxiway and the wind to "sail" the plane straight down the yellow line using only the rudder. Also, you cannot take off or land with full rudder deflection in a plane that has nose-wheel steering. This gives planes with differential braking a higher crosswind component rating. When doing a formation takeoff in planes with differential braking, line up closer to abreast than you would with nosewheel steering. Usually dash-2 has to make some initial corrections during the takeoff roll and when those corrections are made he will drop back and be right on the bearing line.

There are several internal fuel bladders in the L-39... feed tank, saddle tanks, inverted tank. To fuel one involves much sloshing and glug-glug-glugging and waiting for fuel to find all the places to go. There are no fuel pumps other than the main pump from the feed tank. Fuel from the drop tanks and tips are pushed to the feed tank via bleed air. At lower engine RPM there is not enough pressure to push external fuel in so on the ground you are always burning from internal tanks. First the L-39 burns fuel from the feed tank, when some of that is gone it starts allowing fuel from the other tanks. This is done with a float in the feed tank. What you will see is the fuel gauge drop to ~700Kg and then it will stop dropping... what is happening is you are now on external fuel. It will start dropping again after all the external fuel has been pushed to the feed tank. The system is ingeniously simple... push bleed air to the drop tanks, then the output of the drop tanks goes to the tip tanks, and back to the internal feed tank. So drop tank fuel goes out to the tips before coming back to the plane. When the drops are empty the air goes to the tips. Also when there are no drop tanks. If you take off with fuel in the drop tanks but not the tip tanks you can actually land with full tip tanks. When you are on the ground with low RPM there is not enough pressure to activate the drop tank pressure sender and so it thinks the drops are empty. Low pressure = it thinks air is pushing on the sender not fuel. This is why you have a switch to turn off the drop tank light. You only turn it on when you have drop tanks. PS. It's almost impossible to get this airplane out of CG. The front pilot can eject and the airplane will still be in CG. :-)

Fly the real airplane with your feet on the floor... rudder is for takeoff, landing, and taxi only. :-)

Real L-39 stalls like a pussycat... stick talks to you a little bit and let the nose drop and it stops. Deep stall is a lot bumpier - the airplane says "stop doing that to me". But even a deep stall doesn't need much rudder input to keep the ball in the middle. One thing to note is that the L-39 has very substantial secondary stall characteristics. Stall it a little, let it recover and it will stall again when you pull back on the stick at 20 KIAS higher than the first stall. When you get into a good stall or spin the L-39 is a real stick snatcher. Both hands on the stick to have good control of it. To properly simulate this the sim should throw your joystick off your desk if you don't hold on tight. :-) The L-39 doesn't like to spin. The L-29 loves it, the L-39 will make you not want to do it a second time. Also note it's very easy to get on the back side of the power curve during slow flight. Gear and half flaps and when you get a very high alpha it just mushes along. You can have climb power (102%) set and it will plow through the air with the nose up. Also because of this it doesn't pick up airspeed easily when the airplane is dirty. Dropping the nose on landing doesn't do much, you have to add power AND drop the nose, and add power early because of the long spool-up time. Best to set 78% at the perch on a break, leave it there, and manage the descent with angle of bank instead of pitch. There can be some advantage to this - if you are a bit high on the landing you can push the nose down and it doesn't pick up speed. You do not, not, not want to be low and slow on landing in an L-39. Inverted spin is a prohibited maneuver in the L-39. AI-TL is very robust engine. As demonstrated by the crash near Boulder City NV, the plane pancaked into the desert, probably 20-30G impact, and the engine was still running. You can tail-slide the airplane, but I wouldn't recommend it.

When you pull the stick back to round-out the airplane prior to landing, the term for this is "to flare" or "landing flare". If you do this with too quickly the aircraft will rise and this is called "ballooning". I am sure this is what you mean by the term "parachuting". I have 400+ hours in the L-39ZA and am friends with Jan Vlček's son, Václav who was an engine specialist for Aero (now works for Honeywell, I think). If you are interested, I have some phrasing and grammar suggestions for the manual. One thing I noticed right away is that the L-29 is called "Dolphin" in the beginning. While no doubt this is correct, I have always seen it spelled Delphin, even in English.

Do the flight models in DCS have understated pitch sensitivity? I was watching a youTube video of two DCS aircraft in formation and they were flying really good formation, but dash-2 was making these +/-2 degree pitch changes and his aircraft wasn't moving much. At 275 knots, a 2 degree pitch change results in a 16 foot altitude difference in one second. That's plus or minus a house. I've flown lots and lots and lots of close formation in the L-39 and you just don't see pivoting pitch changes like that, rather dash-2 will oscillate up and down and it will look more like porpoising smoothly in a sine wave but you don't see the aircraft "pivot" around the CG. What am I missing? To me it seems like the aircraft needs time to "bite" the air and accelerate into the pitch change rather than just "pivot".

Anybody ever see an English manual for the real plane? I am curious about a few things.. What is Vle and is Vlo any different? What's Vfe for the takeoff/maneuvering flaps, all the way up to Vne/Mmo? What's Vfe for the fully extended flap position? When landing, what comes down first, flaps or gear? If Vfe is higher than Vlo then seems like first flap position to get a little drag and drop the airspeed to Vlo... but maybe it's the other way around? Dive brakes seem a lot like the boards on the L-39... below 350 kph, no effect, above 500 kph feels like you deployed a parachute, above 700 kph better have your harness tight. :-)

Looking forward to a DCS MiG-23 module. This is me driving...