[CLOSED] wings break off at 4g

[Anatoli-Kagari9]

Honestly, and although I really like DCS World for what it is as a flight simulation platform, and because I am not interested in modern combat aircraft, the more I use it the more I tend to think that the models that go better with this way of modelling ( or better said, not modelling ... ) any sort of force feedback are still the helicopters. I

 

When I use the UH-1H, I believe I am acting the closest to real DCS can get in all aspects ( excluding the modern fightters which I do not own...)

 

After a few hours with the p51d, Fw190 and now the Me109, I managed to be able to fly without breaking many wings / wing tips ( well, I still break too many in the 109 K4 :-/ ), but I feel the kind of technique I taught my brain to use is far from plausible / realistic... A true pitty because, other than that, I find some aspects of these flight models really good!

[NineLine]

There is already a thread open on this topic. Closed.

[Anatoli-Kagari9]

Glue for wingtips!

 

Brand: "ACME Flaps"

 

Quantity: just one full turn of the flap wheel, or even less if you don't want to loose much energy in the heat of your dogfight...

 

Strength: Hmmmm, let me see... Yesterday at Gavagai's server I scored 8,5 G recovering from a dive. Wingtips were still there when I looked for them :-)

 

Side effects: A horn sounding all of the time, if, preferably, your gear is UP!

 

Does it make sense, aerodynamically I mean? I think it does... it certainly helps bringing the lift distribution more towards the root of your wings and changing the lift vector... This is probably accounting for the lesser loads on the wing tips ( ? )

Edited January 13, 2015 by jcomm

[NeilWillis]

Isn't there a maximum speed at which flaps can be safely deployed?

 

I'd be surprised if the real thing would behave in a way that meant flaps would be useful in dive recovery at speeds sufficient for you to generate 8.5 G

[gavagai]

The wings might have still been warped.

 

I've more or less cured myself of breaking the wings off the 109, but I had to force myself to stop rolling while pulling hard. It's the asymmetrical loading that is the kiss of death, not the G loading by itself.

[Anatoli-Kagari9]

Isn't there a maximum speed at which flaps can be safely deployed?

 

I'd be surprised if the real thing would behave in a way that meant flaps would be useful in dive recovery at speeds sufficient for you to generate 8.5 G

 

 

Yes, but, it's just a tiny bit of flaps... Just the sufficient to start hearing that irritating horn...

[Solty]

Wings for both Bf109 and P-51 are too weak. P-51 breaks wings at 7+ Gs. :(

[Crumpp]

Does it make sense, aerodynamically I mean?

 

Adding flaps reduces the load factor the wing structure is capable of withstanding.

 

I've more or less cured myself of breaking the wings off the 109, but I had to force myself to stop rolling while pulling hard. It's the asymmetrical loading that is the kiss of death, not the G loading by itself.

 

Same here, I have to watch those spiral dives in the P-51 or Dora.

 

Isn't there a maximum speed at which flaps can be safely deployed?

 

Depends on the amount of flap you are deploying. Small angles can be deployed at high speeds on most aircraft.

[Anatoli-Kagari9]

Adding flaps reduces the load factor the wing structure is capable of withstanding.speeds on most aircraft.

 

true, but probably, in this K4, also moves it away from the tips...

[Aginor]

Sometimes I think that ripping off the wings is not correlated to G forces.

Since the last update I ripped my wings off twice, once was when flying too fast in a dive, and the other one was while flying a roll (ailerons and rudder to get maximum roll rate, I didn't watch the Gs but I doubt you can achieve more than a few Gs in a roll)

Other times I pulled more than 8 positive Gs in one mission (but no roll involved or not much) and nothing bad happened.

 

So something is wrong there, I have to do more tests.

[Crumpp]

Wings for both Bf109 and P-51 are too weak. P-51 breaks wings at 7+ Gs

 

A normally loaded P-51D in clean configuration has a limiting load factor of ~6.75G's.

 

 

The FW-190D9 is limited too 5G's as a category H5 aircraft under the RLM system.

 

Load factor depends on weight and engineering safety factor. You have two types of load factor limits in aircraft, proof and ultimate. Proof is where the structure is going to take progressive damage and ultimate represents structural failure at a one time single axis load. Both limits assume an undamaged airframe in new condition.

 

Normally loaded P-51D = 9478 lbs

 

64000/9478 = 6.75G proof load factor

 

The Germans used a high safety factor so actual load factor the structure can stand is the same.

 

The UK and USA use a safety factor of 1.0 for proof (6g) and 1.5 for ultimate load (9G).

 

Germany used 1.35 for proof and 1.8 for ultimate.

 

H5 category limits to 5G.

 

5 x 1.35 = 6.75G under the USA/UK system for proof load factor.

 

So different safety factors = same structural strength.

 

It is good to finally see a sim that actually simulates an airplanes structure. If we can just get weather and gusting it will be even better!

Edited January 13, 2015 by Crumpp

[Crumpp]

true, but probably, in this K4, also moves it away from the tips...

 

It certainly could. 8.5 G is past proof and getting close to ultimate load factor so I think you got lucky.

 

The airframe damage exceeding proof is not only progressive, it can be insidious too. The pilot will not be aware of it until on the ground or the airframe fails at a much lower load factor.

 

Personally I think things are fine with the structural modeling and we should adjust our tactics accordingly. Off topic but related, the pilot physiological model needs more work than the airframe structure, IMHO. I think our pilot is modeled after a modern jet pilot with G-suit and straining maneuvers. I hear him grunting.

 

World War II pilots knowledge and training on load factor effect on the human body ranged the gamut form somewhat savvy to no useful training at all. The big advantage for the USAAF is the standard issue G suit that came into use in 1944 and the Germans the seating position. It will make a big difference in our dogfights when aircraft with upright seating come out.

 

At 4G's a pilot in an upright seat can pass out pretty quickly and even lower for gradual onset load factor exposure.

Edited January 13, 2015 by Crumpp

[Solty]

A normally loaded P-51D in clean configuration has a limiting load factor of ~6.75G's.

 

 

The FW-190D9 is limited too 5G's as a category H5 aircraft under the RLM system.

 

Load factor depends on weight and engineering safety factor. You have two types of load factor limits in aircraft, proof and ultimate. Proof is where the structure is going to take progressive damage and ultimate represents structural failure at a one time single axis load. Both limits assume an undamaged airframe in new condition.

 

Normally loaded P-51D = 9478 lbs

 

64000/9478 = 6.75G proof load factor

 

The Germans used a high safety factor so actual load factor the structure can stand is the same.

 

The UK and USA use a safety factor of 1.0 for proof (6g) and 1.5 for ultimate load (9G).

 

Germany used 1.35 for proof and 1.8 for ultimate.

 

H5 category limits to 5G.

 

5 x 1.35 = 6.75G under the USA/UK system for proof load factor.

 

So different safety factors = same structural strength.

 

It is good to finally see a sim that actually simulates an airplanes structure. If we can just get weather and gusting it will be even better!

 

NAA report no. 8679

 

 

7.5G was just for P-51D that was overloaded to 11.600lbs. We loose wings at 7G with 68% of the fuel load. 7.5Gs is only for the P-51 that has all tanks full and additional 110galon tanks under wings. Normal P-51D should withstand up to 10+Gs. Take into account the 1.5 ultimate load. At ultimate load the wings should break, not at safety factor. It is 1 ton heavier plane that has that limit.

Edited January 13, 2015 by Solty

[Crumpp]

7.5G was just for P-51D that was overloaded to 11.600lbs. W

 

That is an NACA report and the load factor is with 110 gallon wing tanks. Yes, they will pull the wings offs sooner than just adding weight. Lot of structural drag and twisting moment on the wing with the tanks.

 

The POH limits the type to 6 proof at 8000 lbs. Weights above that divide 64000/ weight to get load factor but never above 6G's.

 

64000/11600lbs = 5.5G's

 

5.5G X 1.5 = 8.2G's ...... 7.5G is the limit because of subcomponents and not the airframe.

 

Subcomponent limits set the actual in flight limitations, it is most commonly the engine mounts are limiting but in this case it is the tanks.

 

We loose wings at 7G with 68% of the fuel load.

 

Single axis, single exposure??

 

I have not seen this with my P-51 but I have not really checked it out.

 

Every time I have lost my wings and looked at the track I have discovered it was me not the model. Only when I fly around pulling asymmetrical loads and after several exposures above the proof limit have my wings failed.

Edited January 13, 2015 by Crumpp

[Nedum]

At 4G's a pilot in an upright seat can pass out pretty quickly and even lower for gradual onset load factor exposure.

 

Where did you get this iformation from?

4G's is "normal workspace" for an Fighter Pilot without any g-suits.

With old g-suits is nothing special.

With new g-suits ("giraffe") a Pilot can see now colors and can stay at 9 gs without special breathing technics for more than 3 minutes and clear the cubic!

 

look from 11:30 minutes

 

 

A healthy and trained pilot has no problems with 4 gs.

[NineLine]

 

I have not seen this with my P-51 but I have not really checked it out.

 

Every time I have lost my wings and looked at the track I have discovered it was me not the model. Only when I fly around pulling asymmetrical loads and after several exposures above the proof limit have my wings failed.

 

 

Yes, I have the same results, generally if I am damaging the P-51D it's pilot error, although I havent been in it in a few weeks.

 

That said, this is the 109 section, lets stay on topic.

[NineLine]

Where did you get this iformation from?

4G's is "normal workspace" for an Fighter Pilot without any g-suits.

With old g-suits is nothing special.

With new g-suits ("giraffe") a Pilot can see now colors and can stay at 9 gs without special breathing technics for more than 3 minutes and clear the cubic!

 

look from 11:30 minutes

 

 

A healthy and trained pilot has no problems with 4 gs.

 

Yeah, I have seen reports when testing G suits back in the 40's that state a pilot would start getting tunnel vision around 6-7 without a suit, so I think 4Gs is a little low...

[Crumpp]

Solty,

 

I do feel your pain with the wings coming off. Without a Mk II Cheek to Seat interface I have shed a few wings in both the Dora and Mustang.

[SlipBall]

I think it has always been clear to most of us that it has been pilot error...no fear of destroying the aircraft or even possible death, just select fly again :P

[NineLine]

I think it has always been clear to most of us that it has been pilot error...no fear of destroying the aircraft or even possible death, just select fly again :P

 

Well, with the K-4, there was/is an issue, but internal builds feel better so its getting worked on, but we are beta after all... that said, nothing is going to save me due to my skills, or lack there of :)

[SlipBall]

just fly like you have to return the keys to your base commander :D

[Crumpp]

Yeah, I have seen reports when testing G suits back in the 40's that state a pilot would start getting tunnel vision around 6-7 without a suit, so I think 4Gs is a little low...

 

I have not doubts on the results of the reports.

 

One has to pay careful attention to the onset rate, exposure times and disposition of the subject.

 

The median threshold for symptoms to appear is 4.1G's in a relaxed subject without a G suit and Rapid Onset rate. Out of 1000 subjects, 500 were asleep at 4.8G's.

 

 

Look in the P-51 POH, the dive recovery load factor is limited to 4G's because of pilot physiology and G tolerance not because of the airplane.

 

 

Onset rate has a huge effect on tolerance. Rapid Onset rate exposure is almost unlimited without effect for a few seconds. Gradual onset rate for 10-15 seconds will put most people to sleep.

 

 

A huge factor is stress. Stress lowers human tolerance to accelerations. Two human beings trying to kill each other is a pretty stressful event.

 

The charts come from the NATO Study on G tolerance. It includes a pretty summary of the history of G tolerance research.

 

During World War II and some countries just prior to the war, there was an explosion of G tolerance research with varying results and degrees of success.

 

IMHO, the most accurate World War II pilot physiological model would be based on an upright relaxed individual with a penalty for stress. Modifiers would be the few primitive G suits and seating position to give historical advantage where it existed.

[Crumpp]

One last thought on the subject.....

 

A world war ii pilot tailored physiology model would help us not break our planes too! Based on the graphical information above for onset rate vs exposure something like:

 

1. Breathing increase at ~2.5G's

 

2. Greyout at ~ 4.1G's

 

3. Blackout at 4.8G's

 

4. GLOC with 30 seconds (+) nap time at 5.4 G's

Edited January 13, 2015 by Crumpp

[Solty]

A normally loaded P-51D in clean configuration has a limiting load factor of ~6.75G's.

 

 

 

64000/9478 = 6.75G proof load factor

 

The Germans used a high safety factor so actual load factor the structure can stand is the same.

 

The UK and USA use a safety factor of 1.0 for proof (6g) and 1.5 for ultimate load (9G).

Show me that report that states this?!:huh: The lowest I saw is 7.5

[Crumpp]

I stand corrected, the POH limit is 8G's at 8000lbs.

 

Weight adjust the limit accordingly.

 

P-51D clean configuration fighter with pilot = 9478lbs equals a 6.75 G limit.

 

I missed the note on 8 G's in the manual.

 

Unfortunately none of the airplane limits trump the pilots....

Edited January 13, 2015 by Crumpp