Guys, I have a question regarding the new Inibuild A320.
I am using the tablet to compute take off performance, feed the data into the MCDU etc etc…
I find that using those data, it takes what seems to me to be way too long for the aircraft to accelerate on the runway, and I find myself being able to rotate dangerously close to the end of the runway.
My question is quite simple: is this a known issue with this particular aircraft, or am I doing something wrong (which I don’t know what it is) ?
Try using the one below. It has given much better results. The problem with the tablet is not the acceleration but instead the V1 value I believe. If you are in a long runway its almost 150 knots always regardless of your weight or flap config.
Try the same weight/config in a short runway and V1 calculated is much much less (meaning that you could have taken off in the long runway before)
Thank you for highlighting this. Following your post I have done some testing. In my case, my speeds are affected by weight. BUT, there is a big BUT: the EFB doesn’t connect very well with the MCDU, and it is necessary to click several times the REFRESH and CALCULATE buttons to have them actually work. Otherwise, I have a discrepancy between the EFB and the MCDU. Basically I need to make sure both show the same numbers. I don’t think it is intentional, I think it’s a bug. Once I do that, my weight does impact speeds.
I noticed the following though:
the FLEX numbers generated by Inbuild’s model are much too low compared to the online EFB you linked (which I presume is close to a real one ?). That’s why it takes the entire runway to take off.
runway length impact V1, VR, and V2. In the real one, it impacts only V1.
The modelling of this airplane is quite bad actually.
Just note that low Flex temperature means more thrust power and vice versa. Basically you are “fooling the FADEC”
I haven’t dig too much into details lately (I did during Beta) on how different they are but definitely the most impactful feature is the V1-VR speeds.
And V1=VR in 99% of the cases is a clear indication that is not accurate. V1 should be < VR the shorter the runway is otherwise there will be not enough stopping distance.
So yes what generates the delay in rotation is the increased VR as runway length increases. This shouldn’t be the case. Runway length doesn’t impact VR in the real plane.
This has already been investigated during the beta, and we can confirm that the takeoff performance calculations are accurate and as per real world specifications. The above linked GitHub is an approximate guide, as stated in the title of the web page, so we will not be using it as an official source for comparison at this time.
If the calculations have been confirmed to be accurate what about the a/c acceleration. It does seem to be sluggish and use an uncomfortable amount of the runway at times.
Sorry for pointing this back again, but have you tried to do an RTO just before V1 in a ~2000 m runway when V1~VR and you are rotating at the touchdown point on the other end?
That does not look to be accurate for real world specifications.
I would like to see how the TO calculator from Simbrief when is deployed compares to all the different options.
Guys, the person who responded above on behalf of MSFS is totally and demonstrably … let’s say “mistaken”: in the real A320 (and like any real aircraft actually), everything else equal, VR isn’t impacted by runway length. Unlike Inbuild’s model (which is therefore wrong).
Any ATPL student knows that. Read up on CAP698 (CAA JAR-FCL Examinations Aeroplane Performance Manual).
For your convenience, you can download it <here>.
Out of V1, VR and V2, only V1 is impacted by runway length (to be more precise, its TORA).
Let me prove it to you. I just recorded this RTO at LEBL, runway 06L. I intentionally took a runway with a long TORA, so that my VR was (wrongly) calculated to be 150kt. Acceleration is totally unrealistic at the calculated FLEX TO Temp, and the aircraft then can’t stop in time:
In regard to rotating at the touchdown point at the other end, this will depend on many factors. Weight, wind conditions i.e. tail wind factor, runway condition, runway length, elevation. Depending on the conditions input into the EFB, the takeoff calculator will read from different tables to ensure the correct speeds/flex temp etc. are applied. With your example of a 2000m runway, there is a very good chance you could be rotating on the touchdown point of the other end of the runway depending on the factors listed above! The real-world conditions required not just by Airbus by every regulation in the world are 50ft AGL by the end of the runway in dry conditions, and 30ft AGL in wet conditions.
It may seem to be aggressive compared to other takeoff calculators, however as noted this has been investigated after feedback given during the beta. If you’re loading onto an active runway in the sim to run some tests, and then using the EFB for takeoff calculations, make sure that you not only sync the weights in the EFB, but also to update the runway length if you’ve not spawned in at full-length of the runway!
Just to clarify, whilst I in no terms claim to be a real world expert flying these types of aircraft, when these interesting topics come to light I ensure to verify my sources of information with colleagues or other members of the community who do fly these beautiful birds! Any information I share on here has been verified with those who are type-rated on the aircraft!
Ah you mentioned rotating at the other end of the runway in your post, hence why I mentioned it!
There’s a really interesting discussion on this topic on the iniBuilds Discord server that may help provide some further clarification about the takeoff speeds calculation, which I’ll link below. V1 equalling VR is not uncommon by any means in the A320. You should be able to see the difference if you input data like wet conditions on a short runway into the EFB, and there can be a split in the V1-VR speeds.
When you have a 3500 m runway yes. But how a about a short runway?
SVMT for example. 2100 m long. V1=VR=131 knots, and the rotation happens close to the touchdown zone on the other end (not much stopping distance left to brake).
That’s still fine, its only on really short runways like 1800m and less that you begin to see a split in the V1/VR, it really isn’t an issue at 2100m, this really doesn’t need this much of your energy buddy
