Most Efficient Cruise Altitude and Speed

Australian fighter slang for out of gas .... "on the bones of your arse"

Thanks !

Another rule of thumb is start your descent at 1/2 of your altitude, so for the 30k ft example you would start at 15nm from the base

That doesn't sound right. Double rather than half your alt would give you a more sensible distance.

That doesn't sound right. Double rather than half your alt would give you a more sensible distance.

i was confused by this as well. double (or more) feels more right

Does this mean we will be able to refer to the FPAS page and be able to set super cruise with fuel flow? I hope so, I loved this feature in the VRS F/A-18E Super Hornet in FSX.

Thanks,

Wayne

That doesn't sound right. Double rather than half your alt would give you a more sensible distance.

i was confused by this as well. double (or more) feels more right

I don't think that is quite right. Of course this isn't an end all for all aircraft because it depends on glide ratio of each in idle power, but you aren't going to start your descent at 60nm from a field when cruising at 30k feet in most fighters. That would equate to roughly a 0.5 degree descent if my mental aviation math is right.

10 degrees not 0.5.

It's a rule of thumb and won't be exact, so yeah it won't be too far off for most fighters.

Can you descent from 30k with 15nm to go? Probably, but will likely result in you screaming in at 500kts with the airbake out :lol: Not very efficient! 60nm allows you longer at idle and a slower descent speed, both of which help with efficiency.

To be more specific, IIRC from The Figherpilot Podcast, for the F/A-18C it's double your alt (in thousands) + 10, with the throttles slightly forward of idle (this is to get the exhaust nozzle to close and provide a bit more residual thrust).

A 10:1 relationship would be 300,000:30,000 feet. This is 49.4nm. No way you're going 60nm idle glide let alone 70nm from 30kft. 11:1 is probably near the best you can do at no drag and low GW.

This double plus ten rule is a 14:1 ratio. You'd have to leave in substantial thrust over idle to get that although that may be what they do. It really helps keeping in formation not to follow lead at dead idle.

Sure, but remember if you're descending to ground level that's usually because you want to land. You need to give yourself some space to enter the patern.

10 degrees not 0.5.

 

It's a rule of thumb and won't be exact, so yeah it won't be too far off for most fighters.

 

Can you descent from 30k with 15nm to go? Probably, but will likely result in you screaming in at 500kts with the airbake out :lol: Not very efficient! 60nm allows you longer at idle and a slower descent speed, both of which help with efficiency.

 

To be more specific, IIRC from The Figherpilot Podcast, for the F/A-18C it's double your alt (in thousands) + 10, with the throttles slightly forward of idle (this is to get the exhaust nozzle to close and provide a bit more residual thrust).

Yeah I apologize, I was doing my math backwards. 15nm at 30k would be 20 degrees NL, pretty aggressive. 30nm at 30k would be 10 degrees, 60nm at 30k would be 5 degrees, so your math isn't correct either though. Using the rule of thumb it is a 5 degree descent, not 10. Using actually trigonometry, it is 4.8 degrees so still pretty close to rule of thumb. If the math is hard for people (like it apparently is for me lol) then just setup the intended airfield as a waypoint and wait for it to be 5 degrees nose low before starting the idle gliding descent, assuming the hornet can glide fine at a 5 degree descent which seems reasonable to me.

Haha whoops. My maths was ok I just used the wrong number! Shouldn't use the forum when in a rush.

I'd rather arrive overheard with an excess of altitude than to arrive a bit short. Harder to regain altitude than it is to lose height in the case of a fuel emergency.

Look up high key/low key approach.

In real-world (civil) aviation I always used 3nm for every 1,000 feet I had to descend. So if I've got 10,000 feet to lose, I'd start the descent 30nm out (at a rate-of-descent equal to groundspeed x 5, incidentally). Good rules of thumb.

But of course that was in aircraft that are WAAAAY less maneuverable than a Hornet. ;) And it was rare to get a single descent all the way down anyway; ATC almost always had a step or two in there.

This is a great discussion! I'll have to give some of these numbers a try in the Hornet over the weekend.

EDIT to add:

The CNATRA P-819 "Advanced NFO Strike Procedures" document says:

One technique is to multiply the altitude to lose in thousands of feet by two, then ad 10 NM." For example: if you have 10,000 feet to lose, start the descent 20 nm + 10 nm = 30 nm out.

This document is written for the T-45 Goshawk, but still probably applies to the Hornet. And this way you have an actual Navy rule of thumb to use. ;)

Link to the CNATRA publications, for those who haven't seen these yet (TONS of awesome information and procedures!) : https://www.cnatra.navy.mil/pubs-pat-pubs.asp

Does anyone have an idea when the FPAS page will be implemented? I would really like to have it soon!

It was mentioned by Wags a couple times already as an item the team (or parts of it) is actively working on. So I wouldn‘t be too surprised if we would already get it with the next OB update this Wednesday. I wouldn’t be surprised if we wouldn‘t either though...:)

Possibly this week https://forums.eagle.ru/showpost.php?p=3661070&postcount=80

It was mentioned by Wags a couple times already as an item the team (or parts of it) is actively working on. So I wouldn‘t be too surprised if we would already get it with the next OB update this Wednesday. I wouldn’t be surprised if we wouldn‘t either though...:)

I'm curious, how many devs are there working for DCS and do they work on multi projects at the same time...would you know?

Wags posting something about that too, in mini updates I think.

The short answer is 4.

I'm curious, how many devs are there working for DCS

No sure if it's still true but on the TBS site they say ED has 55 employees.

No sure if it's still true but on the TBS site they say ED has 55 employees.

Yeah I've seen 55 on some other websites that monitor companies all over the world. If you search for CH-660.2.221.000-8 you can find more information about ED.

Thanks all!

Fwiw in fighters because you are normally a pair you descend with some throttle so the wingman has some throttle to play with.

Twice the altitude usually works for a pair and then adjust for runway alignment. -5 for opposite direction descent etc.

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