P-51 Landing Gear Fairings Incorrectly Modeled.

[QB.Shallot]

I understand that I am not bringing new research to the table. My objective was to format the research in a manner that clearly showed that the P-51 gear door fairings are not modeled with the same philosophy as other aircraft with the IL2 BOX simulation. Historically, there were maintenance issues with many aircraft shown within the IL2 simulation (the Lagg-3 and La-5 being perfect examples) that while in real life suffered from many debilitating issues, are modeled as though they exist in a perfect world. This is the only way to model aircraft in an accurate manner, as many maintenance issues had a wide variety of factors that affected performance.

 

The information provided below shows that the landing gear fairings detaching from the aircraft was, in fact, a maintenance issue and not an issue with the aircraft’s fundamental design. Thus, it would be inconsistent to model the issue (which was rectified by the time period of the BOBp expansion), while most other A/C are modeled in a “factory perfect” state.

 

The Claim:

The modeling of the P-51D-15’s landing gear fairings detaching at 505-520 MPH is inaccurate, and not in line with IL2’s aircraft modeling philosophy.

 

When questioned on the subject, Developer @Gavrick provided the following as evidence to refute it:

https://cdn.discordapp.com/attachments/588015716477960206/637004879445098526/image.png.f05ae0df463eb423f291304b57a0e145.png

 

 

What refutes the claim: 

 

Full report linked here: http://www.wwiiaircraftperformance.org/mustang/p-51d-dive-27-feb-45.pdf

 

Page 2 of  the report, point 8: “Following a failure of the left landing gear fairing door and strut fairing…”

Note, this merely reports a failure, not a complete detachment from the aircraft. 

Further, it does not list the failure as a recurring issue, but a single failure that occurred during a series of 31 dives. It was not reported as a recurring failure and was concluded to be a reparable maintenance issue.

 

The conclusion of the report states the following: “...critical nature of...deflection of landing gear fairing doors at high indicated speeds, the manufacturer should be requested to demonstrated the airplane at an indicated airspeed of 505 MPH.”

 

What shows the issue was concluded after the memorandum was written:

Page 2 of the report: “...tests were conducted and results wired to the manufactured...27 October 1944 on maintenance of up-latches on P-51B, C, and D airplanes”

 

Further evidence to support the claim:

 

It should be noted that the tests in the above report took place only a month after the technical order listed below, meaning it’s highly likely that the measures listed below were not taken as of yet.

https://www.avialogs.com/aircraft-n/north-american-aviation/item/4753-to-01-60j-22-inspections-of-landing-gear-uploack-and-main-gear-fairing-door-locks-p-51b-p-51c-and-p-51d-airplanes

 

To quote the Technical Order (Page 1 point 1), “Due to the possibility of improper adjustment of the landing-gear uplock and the landing-gear fairing door lock which may cause loss of the fairing door during flight, all P-51B, P-51C, and P-51D airplanes will be inspected immediately…”

 

The above passage confirms that the issue with the fairing door locks was not on a design level, but on a maintenance level. 

 

The following technical order all but confirms the rectification of the issue:

https://www.avialogs.com/aircraft-n/north-american-aviation/item/4857-to-60je-9-installation-of-landing-gear-uplock-system-p-51d

 

“1. To decrease the possibility of the landing gear extending during flight since only hydraulic pressure holds the gear retracted, a landing-gear uplock system will be installed….”

 

“2. The instructions for accomplishing this change as contained in Noth American Service Bulletin 51-188 dated 29 June 1944, are as follows:...”

 

All evidence shows that the issue of the landing gear fairing failure during high-speed flight was a maintenance issue that was A) Not consistent and B) rectified in short order. 

 

Conclusion:

The P-51D-15 should not be modeled with these issues within the IL2 stimulation, as it clashes with the philosophy of how aircraft are modeled in their “factory perfect” state. A more consistent way to model the P-51D would be to remove the detachment of the landing gear fairings, and simply maintain the detachment of various control surfaces at extremely high speeds. This is in line with how the majority of IL2 BOBp aircraft are modeled.

 

Proof of the phenomenon is demonstrated in the linked video: https://streamable.com/tvvh5n

 

Quick thanks to @KW_1979 and @NZTyphoon for providing data on other threads surrounding the subject.

 

Edited April 30, 2020 by QB.Shallot
Formatting

[357th_KW]

Bumping this as the P-51B development cycle has begun, and this issue will impact it as well.

[QB.Shallot]

@KW_1979 Appreciate it. I’ve PM’d to Gavrick who has reacted to the post, and another dev who confirmed that the post has been received by the team. I was hopeful that it would be fixed in the last few updates, but I think it’ll continue to persist until the 51B/C is dropped. Part of me hopes that a similar approach will be taken with the Razorback 47’s, and that the later variant might get an FM polish up as well. 

[Gavrick]

I accept the argument that the gear door locks should have been fixed in the regiments. At D-15, I think this really should not have been, I will correct it.

[QB.Shallot]

@Gavrick I appreciate your response, but I would say that it would not be accurate to model the gear doors coming off in the P-51B/C either. As I have noted, the test report that is used as proof had this issue occur one time out of 31 dives on a single example of a P-51D. There is no indication to show that this issue was occurring consistently, but rather as a result of repeated stress on the landing gear locks. 

I don't think it would be in the interest of realism to model this issue on the BoN P-51B.

[QB.Shallot]

Follow up to @Gavrick seeing as the P-51B development cycle is probably in full swing now. 

As shown by the chart above, dive speeds are shown to be in excess of 570mph near sea level. Now while this is important for a separate argument on the P-51's compressibility modeling, the important part is that issues with landing gear fairings are nowhere to be found in the report.

This indicates that even the Mustang III, equivalent to the P-51B/C, had no issues exceeding the current in game limit of the P-51 in excess of 50 mph. This means that the initial report that used to model the landing gear fairing failures in the P-51 in IL2 was a maintenance issue that was not at all consistent. In fact, it was inconsistent enough that the suggested dive limit is well in excess of the speed that the failure took place. It should be noted that this report was made in March of 1944, which is well before the maintenance order to rectify potential landing gear fairing problems was issued. 

 

In conclusion, modeling the landing gear fairing's detaching on the P-51B/C/D in a high speed dive is inaccurate, as it was a highly inconsistent occurrence. 

 

Note, the report was pulled from this link: http://www.wwiiaircraftperformance.org/mustang/mustang-tactical.html

Edited August 14, 2020 by QB.Shallot

[Cecil]

On 6/16/2020 at 6:21 AM, Gavrick said:

I accept the argument that the gear door locks should have been fixed in the regiments. At D-15, I think this really should not have been, I will correct it.

 

@Gavrick whatever happened to this?  The gear doors still rip off at exactly the same speed.

Edited September 29, 2020 by Cecil

[Bremspropeller]

Bill Marshall's book mentions gear-door uplock kits were introduced in the ETO in late April 1944 and wheel door fairing latches were modified and introduced in July.

Edited September 30, 2020 by Bremspropeller

[Gavrick]

On 9/29/2020 at 4:47 AM, Cecil said:

whatever happened to this?

I can't promise, but hopefully soon enough.

[Cecil]

On 10/3/2020 at 8:34 AM, Gavrick said:

I can't promise, but hopefully soon enough.

Hell yeah, it's fixed!!! Thanks!  ?