Glide distance [info]

[Pavlin_33]

To whom ever it may concern:

Slick Su-27 with about 3t of fuel oe less, needs 10 x height in km distance to glide safely back to base.
For example: height is 3km x 10 = 30km glide distance required in order to land safely with engines off.

Edited February 12, 2024 by Pavlin_33

[Ironhand]

Out of curiosity, what airspeed and/or sink rate did you use to achieve that 10:1 glide ratio?

[WildBillKelsoe]

5 minutes ago, Ironhand said:

Out of curiosity, what airspeed and/or sink rate did you use to achieve that 10:1 glide ratio?

and also meteo conditions. do they still have their wings? Is base commander cool with the results? important and even critical questions indeed!

[Ironhand]

1 hour ago, WildBillKelsoe said:

and also meteo conditions. do they still have their wings? Is base commander cool with the results? important and even critical questions indeed!

My assumption was that it was “0” wind. As for the rest? Well…

IIRC the best speed for glide distance in an empty Flanker was around 400 km/hr. So I was wondering what he found. I don’t think I ever bothered to check speed for glide time.

[Pavlin_33]

On 2/12/2024 at 2:41 PM, Ironhand said:

Out of curiosity, what airspeed and/or sink rate did you use to achieve that 10:1 glide ratio?

I usually never go below 400kph. I am not sure why, I guess 'cause the spedometer starts having finer scale there, so I imagine that might be the lowest drag speed.

Airbus A320 has it's best glide speed around 210knots which is more or less within this speed range. I could be totally wrong here, also.

 

[Pavlin_33]

On 2/12/2024 at 4:39 PM, Ironhand said:

My assumption was that it was “0” wind. As for the rest? Well…

IIRC the best speed for glide distance in an empty Flanker was around 400 km/hr. So I was wondering what he found. I don’t think I ever bothered to check speed for glide time.

Yes, it's for more-less calm winds. This is by no means a goto procedure to follow in case of both engines goin out, but rather a quick rule of thumb.

My procedure is:

- engines are out

- jettison all stores

- check height and distance

If within the simple rule, chances are high for successful landing.

Sometimes I run out of fuel when flying in MP

Edited February 13, 2024 by Pavlin_33

[Ironhand]

2 hours ago, Pavlin_33 said:

I usually never go below 400kph. I am not sure why, I guess 'cause the spedometer starts having finer scale there, so I imagine that might be the lowest drag speed.

Airbus A320 has it's best glide speed around 210knots which is more or less within this speed range. I could be totally wrong here, also.

 

Since asking the question, I made a few experiments of my own. I assume my engines are out due to having run out of fuel. That seems more likely than losing both due to battle damage since, when that’s the case I’m usually missing a wing or two as well.

At any rate, assuming empty tanks and nothing hanging off my wings, best glide speed for distance seems to be right around 400 km/hr. 300 km/hr, on the other hand gives significantly more glide time, if you’re searching for somewhere nearby (field, road, etc) to touch down.

[Pavlin_33]

18 hours ago, Ironhand said:

Since asking the question, I made a few experiments of my own. I assume my engines are out due to having run out of fuel. That seems more likely than losing both due to battle damage since, when that’s the case I’m usually missing a wing or two as well.

At any rate, assuming empty tanks and nothing hanging off my wings, best glide speed for distance seems to be right around 400 km/hr. 300 km/hr, on the other hand gives significantly more glide time, if you’re searching for somewhere nearby (field, road, etc) to touch down.

I sometimes have very low fuel, so I check if I can glide it in on idle power - most use cases for me.

[Ironhand]

1 hour ago, Pavlin_33 said:

I sometimes have very low fuel, so I check if I can glide it in on idle power - most use cases for me.

So does your original post reflect a powered glide (idle engines) or a non-powered glide? Just curious.

[Pavlin_33]

1 hour ago, Ironhand said:

So does your original post reflect a powered glide (idle engines) or a non-powered glide? Just curious.

Both - it works in no-fuel state as well as idle.

[WildBillKelsoe]

I would try with dry hump static thrust (donning on my techno garbage cape here) and report my findings! Get to work, potential base commander!

[average_pilot]

Best glide speed is actually an angle of attack. https://www.av8n.com/how/htm/aoa.html

Quote

Many of the airplane’s critical performance numbers are really angle of attack numbers:

• The stall occurs at a particular angle of attack.
• The smallest power-off descent rate occurs at a particular angle of attack.
• The best power-off glide ratio occurs at a particular angle of attack.
• The recommended “approach speed” is really an angle of attack recommendation.
• The best rate of climb occurs at a particular angle of attack.
• The best angle of climb occurs at a particular angle of attack.

The problem is often finding information about those AoA's for the different airplanes because aviation pilots are obsessed with IAS and rule of thumb mental calculations.

[AndyJWest]

If all else fails, you can always resort to armchair test-pilot stuff. It shouldn't be too difficult to get a ballpark figure for the best glide speed for a given configuration by careful observation of airspeed to rate of sink ratios, and a little maths. And if you have AoA information available, use that instead of airspeed.