Jump to content

Sustained turn rate at 31.5 °/s with flaps on!?


EvMstein

Recommended Posts

Although I fly DCS Heatblur F-14B for years, this is the first time I can do sustained turn rate at 31.5 degree per second. I heard people talk about it, but I myself never achieved it before.. I thought 31.5 °/s is instantaneous turn rate but it turns out you literally can pull 31.5 in complete cycle, more and more.. I'm quite in shocked when looking at the telemetry data in Tacview.

 

I guess the community are familiar with topic like this and probably hate me for asking the same question about turn rate again and again, but 31.5 jeez.. I couldn't resist.

 

Is 31.5 STR really achievable IRL for the F-14B?


Edited by JUSOCOM
Link to comment
Share on other sites

Fastest I have seen as sustained turn speed has been Su-27S performing 360° circle in 12.7 seconds. That is about 28,5°/s as sustained.

 

31,5°/s circle means 11,42 seconds time.

i7-8700k, 32GB 2666Mhz DDR4, 2x 2080S SLI 8GB, Oculus Rift S.

i7-8700k, 16GB 2666Mhz DDR4, 1080Ti 11GB, 27" 4K, 65" HDR 4K.

Link to comment
Share on other sites

Would you mind elaborating the conditions to achieve that? Namely, your speed, altitude, outside air temperature?

 

Edit: Oh and payload and fuel

TAS: 275-280 kts (0.39), ASL: 250-300 ft, AoA: 11-11.5°, G-load: 7.6-7.7 G, outside air temp is 20°C

 

No missiles and ammunition / Fuel stats less than 1-1.5K lbs if I remember it correctly.


Edited by JUSOCOM
Link to comment
Share on other sites

Firstly, I wouldn't trust what the tacview data says; I've seen it give numbers that cannot be reproduced in-game. Secondly, you're testing the most favorable (non-realistic) conditions possible for sustained turn rate. The closest actual turn rate data we have is measured at 5000ft MSL, on a standard day (15 C), with 4xAIM7 4xAIM9 loadout at a gross weight of 55,620 lbs. This data is also not at full flaps. Your test is essentially at sea level with minimal drag at nearly empty weight, with full flaps. There is no validation data that can be compared to your scenario to know if that sustained rate is possible or realistic. We have added drag penalties to high speed full-flap deployments to prevent people from abusing and unrealistically misusing the flaps for a turn rate advantage in the exact situation you're trying to test. To my knowledge, this scenario has never happened in real life since it would likely result in damage to the airframe. The truth is that we don't know what full-flaps does to sustained turn rate since there is no data, and the best possible sustained turn rate speed is well above the maximum full-flap deployment speed.


Edited by fat creason

Systems Engineer & FM Modeler

Heatblur Simulations

Link to comment
Share on other sites

The first question to answer is can a Tomcat pull 7.5g at 275 kts at that weight at sea level. If the answer is yes, then it is just a matter of how much drag that generates vs the available thrust. At that really low weight with those very strong engines, it is probably within the realm of possibility.

[sIGPIC][/sIGPIC]

Link to comment
Share on other sites

The thing is, if you are faster than 225 knots with AUX flaps full down you are going to damage the plane, let alone over-g the airplane. While it may be possible in the sim at very light weight, a clean aircraft and at sea level, the plane might be written off or badly damaged in the end. Just the perks of not having FBW or any envelope protections - if you can do it, she'll let ya!

Link to comment
Share on other sites

To my knowledge, this scenario has never happened in real life since it would likely result in damage to the airframe. The truth is that we don't know what full-flaps does to sustained turn rate since there is no data, and the best possible sustained turn rate speed is well above the maximum full-flap deployment speed.

 

Could it be then expected that a such damage to airframe will be added if using full-flaps deployed in such scenario, or would it be ignored as there is no data?

 

This is one of these questions that what should be done, when there is no data and yet there is possibility in simulation to gain such advantage, that might (or not) fall in the abusing simulator limitations.

 

Very difficult to decide what to do, or not to do, right?

i7-8700k, 32GB 2666Mhz DDR4, 2x 2080S SLI 8GB, Oculus Rift S.

i7-8700k, 16GB 2666Mhz DDR4, 1080Ti 11GB, 27" 4K, 65" HDR 4K.

Link to comment
Share on other sites

Could it be then expected that a such damage to airframe will be added if using full-flaps deployed in such scenario, or would it be ignored as there is no data?

 

This is one of these questions that what should be done, when there is no data and yet there is possibility in simulation to gain such advantage, that might (or not) fall in the abusing simulator limitations.

 

Very difficult to decide what to do, or not to do, right?

 

Flap and slat damage is modelled already. Overspeed them and they get stuck or you get a skid/skew/asymmetry.

Link to comment
Share on other sites

So, there's no data to check against but the FM does well simulating drag and lift even in this exact situation plus damage. I don't see a problem then. It's not like you gonna be a king of the sky for long running on fumes.

🖥️ Win10 i7-10700KF 32GB RTX3060   🥽 Rift S   🕹️ T16000M HOTAS   ✈️ FC3, F-14A/B, F-15E   ⚙️ CA   🚢 SC   🌐 NTTR, PG, Syria

Link to comment
Share on other sites

I would also like to add that what Fat Creason means, is no charts, no hard data. However, we know from our SMEs and Grumman reports that the flaps deployment would drastically increase its turnrate below 250kts (and it is said at around 3° or even more per second, but that is a guesstimate). This was an overall accepted feature in general, and the flight model gives if you take it. Ofc there are penalties for that, which are modeled as well.

Heatblur Simulations

 

Please feel free to contact me anytime, either via PM here, on the forums, or via email through the contact form on our homepage.

 

http://www.heatblur.com/

 

https://www.facebook.com/heatblur/

Link to comment
Share on other sites

As Fat Creason and Iron Mike confirmed, no one ever tested the thing in that configuration and that regime, besides you are already breaking the plane if you deploy full flaps at that speed and g.

 

All that being said, let's do some math.

Sea level, standard atmosphere +15 degrees C.

 

Fighter configuration, full burner, maneuvering flaps deployed, 5g sustained turn. Right on the numbers. Hard wing (no maneuvering flaps or slats) 4.4 g.

 

Judging by the effect of full flaps on approach speeds (about 24% boost), with the full flaps down these 4.4 become 5.456. Take away the weight from the missiles and the extra fuel (clean bird, 1000lbs internal fuel) and those 5.456 become 7.09. Add the effects of decreased drag index from 50 to 0 (estimated by fuel consumption and climb profiles about 12%) and those 7.09 become 7.94 g.

 

280 knots, ASL, 7.94g sustained give you 31 degrees per second turn rate. It seams to me, HB have modeled the plane quite accurately :thumbup:

And as Draconus mentioned, at 1000lbs of fuel, you need to start planning your landing approach :D


Edited by captain_dalan

Modules: FC3, Mirage 2000C, Harrier AV-8B NA, F-5, AJS-37 Viggen, F-14B, F-14A, Combined Arms, F/A-18C, F-16C, MiG-19P, F-86, MiG-15, FW-190A, Spitfire Mk IX, UH-1 Huey, Su-25, P-51PD, Caucasus map, Nevada map, Persian Gulf map, Marianas map, Syria Map, Super Carrier, Sinai map, Mosquito, P-51, AH-64 Apache

Link to comment
Share on other sites

So the max rate speed drops to 280 kts when very light?

 

Not necessarily. Your aerodynamic properties are mostly dependent on your airspeed, so under normal conditions (maneuvering flaps only), your best rate speed should still be somewhere between 300-350 knots. What makes this case so specific is the full deployment of flaps. Short of a wind tunnel simulation, i have no idea how much will the increase in air speed effect the extra drag associated with them. When i made the above estimate, i took the OP's example of 270-280 knots purely because those were his test parameters. It helps that 280 knots isn't that far removed from 230-250, so even of some drop in lift-to-drag efficiency is present, it isn't gonna be that large. However, the situation may be quite different above 300. I still expect the best rate to be at a higher airspeed tehn 280 though. Maybe 300-310? Have you tried it in DCS?

Modules: FC3, Mirage 2000C, Harrier AV-8B NA, F-5, AJS-37 Viggen, F-14B, F-14A, Combined Arms, F/A-18C, F-16C, MiG-19P, F-86, MiG-15, FW-190A, Spitfire Mk IX, UH-1 Huey, Su-25, P-51PD, Caucasus map, Nevada map, Persian Gulf map, Marianas map, Syria Map, Super Carrier, Sinai map, Mosquito, P-51, AH-64 Apache

Link to comment
Share on other sites

dcs F15, configured as F14 above, same unrealistic 1000lbs fuel, sl, clean, turn rate ~ 24dgs

Dcs f18c l20, config as above: ~24.5 dgs

 

6.5 dgs advantage for the f14 (abusing flaps)

(All three with over-g)

 

That’s uhm, surprising.

 

Not really...

 

The F-14 has full span slatted flaps and LE slats (not to mention a way higher wing AR), the F-15 has neither, just two half span regular flaps.

 

The F/A-18 is FLCS limited with flaps down.


Edited by Hummingbird
Link to comment
Share on other sites

It also breaks your flaps, which in turn jams your wings weep mechanism. Both of these severally reduce your odds of making back home, from whichever place you were flying over. This on top of the fact that at 1000 pds of gas, you are already not likely to make it back.

 

A more realistic use of maneuvering flaps will get you more like 27 degrees per second or so sustained turn rate.

 

EDIT: do note that with the wings out, the F-14 has a very large wing aspect ratio compared to the other planes on your list. This in theory should make it a very good flyer at lower air speeds, akin to a glider at low weights.


Edited by captain_dalan

Modules: FC3, Mirage 2000C, Harrier AV-8B NA, F-5, AJS-37 Viggen, F-14B, F-14A, Combined Arms, F/A-18C, F-16C, MiG-19P, F-86, MiG-15, FW-190A, Spitfire Mk IX, UH-1 Huey, Su-25, P-51PD, Caucasus map, Nevada map, Persian Gulf map, Marianas map, Syria Map, Super Carrier, Sinai map, Mosquito, P-51, AH-64 Apache

Link to comment
Share on other sites

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...