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Exact readout of flight parameters


frumpy

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Hi there,

I am not (yet) a customer of the JF-17, but might become one.

One thing that bothered me during the free-to-play periods were the exact readouts of altitude and fuel (I think VS and maybe others too). I've never seen an aircraft giving exact readouts like 23,456ft or so, should be rather rounded to 23,460ft or so. Perhaps chinese a/d-converters are different and this is a feature, but I believe not.

Is this a known issue or has this been worked on lately?

 

Thanks, Olli

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7 hours ago, frumpy said:

Hi there,

I am not (yet) a customer of the JF-17, but might become one.

One thing that bothered me during the free-to-play periods were the exact readouts of altitude and fuel (I think VS and maybe others too). I've never seen an aircraft giving exact readouts like 23,456ft or so, should be rather rounded to 23,460ft or so. Perhaps chinese a/d-converters are different and this is a feature, but I believe not.

Is this a known issue or has this been worked on lately?

 

Thanks, Olli

In all available data, and videos of simulators, the altitude is displayed to the foot, no rounding. 

 

So what we have is accurate. 

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Thinking about this... is this the same scaling, regardless of altitude? Like there is still a 1ft resolution at FL300? Is this a real barometric reading or INS or INS with laser?

And is the increase of radar alt with increasing bank (like 30-45°) simulated?

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On the alt readout. I found a video which is supposed to show the HUD, watch at 7:48 (speed x.5 helps).

This is 2-3ft jumps at 2500ft. With increase in altitude, the spacing should enlarge by factor 3-4 at FL400 due to the lower pressure diffrences.

 

Well, I bought the JF-17. Would you be willing to adapt this and intruduce a radar alt increase with increasing bank? 🙂

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11 hours ago, frumpy said:

On the alt readout. I found a video which is supposed to show the HUD, watch at 7:48 (speed x.5 helps).

This is 2-3ft jumps at 2500ft. With increase in altitude, the spacing should enlarge by factor 3-4 at FL400 due to the lower pressure diffrences.

 

Well, I bought the JF-17. Would you be willing to adapt this and intruduce a radar alt increase with increasing bank? 🙂

Good eye

 

Paging @uboats!

 

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2 hours ago, uboats said:

ralt has no issue within roll +/- 40, if more than +/-40, no readout

 

I meant the radar alt is supposed to increase with the bank, until max. RA is reached. Try e.g. with the Su-27 or L-39, until about 30° bank RA stays constant in level flight, between 30-45° it increases with a function like sin((bank-30)*2)+RA. Like 0-30°= 100 ft, 45°=140ft, 60°=190ft or so.


Edited by frumpy
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37 minutes ago, frumpy said:

 

I meant the radar alt is supposed to increase with the bank, until max. RA is reached. Try e.g. with the Su-27 or L-39, until about 30° bank RA stays constant in level flight, between 30-45° it increases with a function like sin((bank-30)*2)+RA. Like 0-30°= 100 ft, 45°=140ft, 60°=190ft or so.

 

for jf17, within 40, readout is correct. >40, readout invalid

also the balt readout can be continuous, per pilot's comment. we don't know whether the video was postprocessed (i.e. sampled frame, this is quite normal).

will further investigate later.


Edited by uboats

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53 minutes ago, uboats said:

for jf17, within 40, readout is correct. >40, readout invalid

also the balt readout can be continuous, per pilot's comment. we don't know whether the video was postprocessed (i.e. sampled frame, this is quite normal).

will further investigate later.

 

Thanks. I think the frames of the video do not play a role. At 7:51 between 2580 and 2577ft you can see the HUD moving, but altitude stays the same.

These 2-3ft jumps may be due to sensor resolution or maybe there is even an internal meters-ft conversation, maybe both, I don't know.

 

So for the RA you say the bank angle is compensated and cut at 40°?


Edited by frumpy
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42 minutes ago, frumpy said:

The frames of the video do not play a role. At 7:51 between 2580 and 2577ft you can see the HUD moving, but altitude stays the same. This may be due to sensor resolution or maybe there is even an internal meters-ft conversation, maybe both, I don't know.

 

So for the RA you say the bank angle is compensated and cut at 40°?

the balt jump almost every 3, looks like the data round in meter, then converted to feet. Or just because the refresh rate

 

yup, RA w/ pitch/roll within +/- 40 works fine. i don't know whether it's compensated or actually it can work in that bank. but within 40 fine, beyond 40, invalid


Edited by uboats

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Hey uboats,

In the same topic, what about the hud refresh rate ? In the video of the hud tape listed above and in the video in the simulator that you listed, we can see that the refresh rate of the digital adi, speed/altitudes gauges and heading tape are not sync at 60fps or more, like they are in DCS.

Accurate HUD refresh rate always adds a layer of finish, a realistic taste. ED and HB modules do that pretty well, what about the Jeff ? :)

Thanks

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The uboats-video shows a referesh rate of ~16 fps (similar to already simulated RA), with larger jumps. I am not sure how accurate this is compared to the real one, but if this effect could be reproduced in DCS I'd be very happy and immersed 🙂

 

As for RA... does the handbook say it's accurate between +-40° bank or it's measured between +-40° bank?

 

Also, in other aircraft like airliners, there is a 2ft resolution of RA near the ground and larger steps (I think 10', I'd have to check) at higher altitude. Do you have definite info that RA display of 1ft is correct? I am not trying to prove anyone wrong, I am just looking for realism, complexity and immersion with this. I like the JF, right now it's the plane I fly most (with Helios).

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Nice. What about the HUD himself refresh rate ?

@After the update edit : Nice little change with this update. :) It's surprising that the pitch ladder is so smooth while the speed and altitude indicators have a very low refresh rate.

Thanks for the change

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@uboatsYes, thanks for changing this! 🙂

 

Still, I wonder if the altitude steps at higher altitude stay the same? You guys set it at 3ft, I think. At 40000ft the baro pressure is only about 1/5 than at sea level. That means the altitude differences which is measured by the baro sensors with a certain resolution (smallest measureable difference) get larger too. I am just deducting here, but judging from this, altitude steps at 40.000 ft should be at around 15ft.

 

Also one thing I noticed: When going at full afterburner, the fuel display in the MFD counts down in steps larger than 1. The HUD fuel display however, still reduces by single steps. Why is this? Perhaps it's a feature, don't know.

 

@Wawar: If you look at the JF-17 commercial video posted above, you can see the HUD itself refreshes faster than the altitude readouts. So I suppose it's pretty much realtime, unlike e.g. the HUD of the F-14. Alt indication is limited by the signals from the barometer, while the HUD itself can refresh faster.

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Just a matter of sample rate and resolution for HUD.

 

In ADC (Air Data Computer), the static pressure has a resolution of 0.0005hg and the dynamic pressure of 0.001hg, with a gradient tolerance of -/+ 0.3%.

 

For comparison, the Flight Control Computer samples and monitors them every 60ms. (Even less for AOA, angular rate and acceleration sensors.)


Edited by LJQCN101

EFM / FCS developer, Deka Ironwork Simulations.

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  • 4 weeks later...

Because the JF-17 is a Chinese aircraft, its instrument outputs the signal in metric units, but it is displayed in English units after conversion, so the data is not rounded.

My native language is not English. This is the content translated by the translator. It may lack enough politeness, may unintentionally offend others, and may not be able to express my accurate meaning.

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