Have you ever tried V1 cut at field limit weight ? I have tried v1 cut with a runway of 2200 m. lenght. For that runway at sea level ONH 1013 14 degrees celcius field limit is 74.000 kgs for maximum takeoff thrust of 26k engine. I tried to takeoff with engine failure at V1 and I couldn't get off before the end of runway. The engines maybe producing less power than they should be at maximum takeoff thrust. (The definition of field limit weight states that in case of a v1 cut the plane should be able to rotate and climb 35 feet above ground level by the end of the runway) Do you have any idea regarding what might be wrong?

You're probably talking about the only aspect of NGX's performance characteristics that is directly and easily measurable! NGX, nee FSX just isn't high fidelity in that regard, it is a good approximation, but RTOWs are most likely to be inaccurate.

 

One specific observation is that single engine performance is much worse than the real aircraft at low speeds, like takeoff and climbout, especially when using assumed, derated thrust or double derating.

So a real 737 pilot shouldn't practice with pmdg! Do you know if there a high fidelity and accurate simulation of 737-800 for PC that a training pliot can practice at home with?

No such thing exists.

 

I suggest you make friends with a sim operator at your airline.

So a real 737 pilot shouldn't practice with pmdg! Do you know if there a high fidelity and accurate simulation of 737-800 for PC that a training pliot can practice at home with?

The only other PC based 737 sim I know about is the Aerosim FMC trainer, which is great for practicing automation, but hopeless at numbers.

 

The most accurate (book performance, systems and failures) PC flight simulator that I have seen is ELITE Pilot v8.0 which only covers GA aircraft, King Air and the essential basics of the MD80.

 

What is it you are trying to specifically practice? I use NGX to practice procedures I don't use very often for which it is pretty good. I don't really care about specific performance numbers too much, if anything it makes you think 'what would/should/can I do if...'

Was you using 'TOGA'?

 

The only other PC based 737 sim I know about is the Aerosim FMC trainer, which is great for practicing automation, but hopeless at numbers.

 

The most accurate (book performance, systems and failures) PC flight simulator that I have seen is ELITE Pilot v8.0 which only covers GA aircraft, King Air and the essential basics of the MD80.

 

What is it you are trying to specifically practice? I use NGX to practice procedures I don't use very often for which it is pretty good. I don't really care about specific performance numbers too much, if anything it makes you think 'what would/should/can I do if...'

I would like to practice non-normal procedures like v1-cut,Rejected takeoff, In flight engine fire. So the performance realism is important.

 

Was you using 'TOGA'?

Yes I was using maximum TO power with 737-800. (no derate or assumed tempature)

I did another test today with the same settings but and this time I used VR CUT in FMC Failures section and was able to climb out safely. Then I realised that V1 was 147 and VR was 148. So I thought 1 knots of difference shouldn't make a difference that much.I than did a V1 CUT again and I realised that engine failure happened before V1 at about 142 knots. So the problem maybe not in the performance of the engines but in the simulation of V1 CUT. Other than that I think PMDG 737 NGX is one of the the most realistic simulations ever. Almost good enough to be used in training.

I would like to practice non-normal procedures like v1-cut,Rejected takeoff, In flight engine fire. So the performance realism is important.

Of course it is up to you to decide how you would like to practice. But the accuracy of the performance does not change the engine failure/fire takeoff procedure. Just reduce the weight of the aircraft to ensure you get airborne.

 

I realised that engine failure happened before V1 at about 142 knots. So the problem maybe not in the performance of the engines but in the simulation of V1 CUT.

Just a piece of pointless but possibly interesting info: the RTOW is based on an engine failure 2 seconds before V1 which would probably be in the ballpark speed. As far as NGX is concerned, I have noticed that it is a bit quick to cut the power, try VR or V2 cut to delay the failure nearer to actual V1.

Some days ago, I took off (not in a simulator) from SBSP (Congonhas, São Paulo - runway extension 1940 m - altitude 2630 feet) in a completely passengers full 737-800 SFP and in a rainy day. Later, I simulated this with the NGX 737-800 SFP (26k) and yes, it's possible to take off safely if you loose an engine at V1 and follow the proper procedure.

 

Teo Halfen

 

Just a piece of pointless but possibly interesting info: the RTOW is based on an engine failure 2 seconds before V1 which would probably be in the ballpark speed. As far as NGX is concerned, I have noticed that it is a bit quick to cut the power, try VR or V2 cut to delay the failure nearer to actual V1.

 

Actually, the engine failure occurs one second before V1. Since the airplane is accelerating at 3-5 knots per second, the speed at which the engine fails should be 3-5 knots less than V1.

Thank you Vagabondo. Your advices were very helpful.

 

Actually, the engine failure occurs one second before V1. Since the airplane is accelerating at 3-5 knots per second, the speed at which the engine fails should be 3-5 knots less than V1.

If this is the case than the engines are a little bit under powered to practice a V1 CUT at the field limit weight. But I can lift off before the end of the runway when the engine failure occurs at VR.

 

Some days ago, I took off (not in a simulator) from SBSP (Congonhas, São Paulo - runway extension 1940 m - altitude 2630 feet) in a completely passengers full 737-800 SFP and in a rainy day. Later, I simulated this with the NGX 737-800 SFP (26k) and yes, it's possible to take off safely if you loose an engine at V1 and follow the proper procedure.

 

Teo Halfen

That could depend on your field limit weight that is listed in the performance dispatch section in 737 flight crew operation manual. If you took off from 17R/35L in a standart day with flaps 5 the field limit weight is 63 tons. So if you were at this and took off safely with an engine faliure at V1 weight than maybe I am doing something wrong.

Is your stabilizer trim setting correct? What speed are you achieving by the end of the runway? V2 for your scenario looks to be about 156 knots, which is the speed you should be at when you are at 35 feet height over the end of the runway. Liftoff should occur at a lower speed. If you are not achieving V2 speed without lifting off, then maybe the engines are "underpowered" as you say. But, if you are accelerating okay, but not lifting off, then it is either in the liftoff simulation, or possibly your technique or trim setting.

Good discussion.

 

Don't try to recertify the plane with NGX, just do the drills.

 

I read it that V₁ is V_EF + 1 SEC as well.

That could depend on your field limit weight that is listed in the performance dispatch section in 737 flight crew operation manual. If you took off from 17R/35L in a standart day with flaps 5 the field limit weight is 63 tons. So if you were at this and took off safely with an engine faliure at V1 weight than maybe I am doing something wrong.

 

In the simulation, I was taking off with 63.8 tons (175 passengers and 3.800 tons baggage) and 5000 kg of fuel. I bumped the power to 27k and applied almost full power before releasing the breaks. TOPCAT indicated that the optimal take off would be with flaps 25. Take off was easy with an engine failure at v1.