Performance charts, economic cruise and maximum range

[Sajarov]

Hi Viggenites!

 

I am planning a long ELINT mission in the Persian Gulf.

 

I Need the performance charts in order to choose the best flight level and economic cruise speed for longest endurance.

 

My payload in the Recce one ( KB, U22/A, 2 Rb.74 and the X-tank).

 

I tried the other day with this payload at FL300 at Mach 0.89 aprox ando I flew for 750 nm.

 

we already have in the RC2 manual the economic cruise speed with altitude. Usually highest the better, but no always.

 

Cheers.

 

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[MYSE1234]

You might find this spreadsheet that I've made usefull. There are some strange things going on with the performance of our Viggen.

 

These top values are when using Mil power, the second is 92% RPM (Nht).

There is also a 2nd sheet with fuel flow relative to temperature.

 

Spreadsheet

Edited April 13, 2020 by MYSE1234

[Sajarov]

Many thanks Myse.

I will take a look.

 

 

 

I found here The Viggen performance charts, specially this one for the Recce payload (payload number 1):

 

But Distans is Distance and Hojd is Altitude... Plane? Kavarvarande bransle? TID in minutes? I dont get how this chart works. Someone can help?

[Holton181]

Many thanks Myse.

I will take a look.

 

 

 

I found here The Viggen performance charts, specially this one for the Recce payload (payload number 1):

 

But Distans is Distance and Hojd is Altitude... Plane? Kavarvarande bransle? TID in minutes? I dont get how this chart works. Someone can help?

 

Gonna help with one word: plané = glidflykt = gliding

Somewhat old word I didn't recognize myself as a Swede, but I found the explanation. I guess it's for descending at idle power.

[tykbry]

Many thanks Myse.

I will take a look.

 

 

 

I found here The Viggen performance charts, specially this one for the Recce payload (payload number 1):

 

But Distans is Distance and Hojd is Altitude... Plane? Kavarvarande bransle? TID in minutes? I dont get how this chart works. Someone can help?

 

I think I get it.

The solid lines are time in minutes. So you can read on the chart how many km in distance you travel at a given altitude. The number is at the top of the line

The broken line is fuel remaining in %. You can then again read how much fuel you will have left at a given distance and altitude. The number is next to the line near the bottom.

 

The first sector called "Stigning" is your climp face. The middle one called "Planeflygt" is level flight. And if the comment above is correct, then the last "Plane", I think it is you cliding/descending, but don't quote me on that.

 

There are some speeds at the top. But I'm not sure about all the keys

Edited April 13, 2020 by tykbry
Clarifying where minutes and % is

[renhanxue]

"Stigning med max släckt" = climb at max dry thrust

"Plané med flygtomgång" = descent at flight idle

"Planflykt distansekonomisk" = distance-economical level flight

"Kvarvarande bränsle %" = remaining fuel in percent

"Tid i minuter" = Time in minutes

Vi = indicated air speed (in km/h)

 

Basically this chart tells you how far you want to climb to get the most distance out of your fuel. You want the dashed lines (remaining fuel) to go as far to the right on the chart as possible (you want as go as far as possible with as much remaining fuel as possible). Looking at the chart you can easily tell though that if you want to go a long distance this means that you climb to about 7000 meters with max dry at 675 km/h IAS or M 0.9, and then you stay there at whatever thrust level keeps you at M 0.9, and then you descend at flight idle, again at 675 km/h IAS or M 0.9. If you do this for as long as you have fuel you'll cover almost 1700km and it'll take you about an hour and 50 minutes. That's all the chart tells you.

Edited April 14, 2020 by renhanxue

[Sajarov]

Many thanks for the explanation Renhanxue.

 

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