P-38 Wing Flap Carriage Connector?

[Hugh_T]

I am currently researching the wing flap geometry for the P-38 Lightning and came across a small issue that I hope you can help me with.

The wing flap connects to the track carriage at 2 points with the upper connection being directly connected to the carriage arm and the lower connected to a 13" rod. This rod is attached to a spherical bearing to the carriage arm which gives it multi-directional movement...however, the smaller tie rod (blue item) on the wing flap itself is attached to a normal AN200 bearing which is not multi-directional.

The geometry setout is set to the default position which indicates a mismatch between the 2 rods. There are options to adjust the alignment of the carriage itself on the main track but not sufficient to correct this misalignment. In addition to that, there is a small elongated nut to attach the 2 rods (#233021) which unfortunately I do not have details for...I am hoping that someone may have those details.

I wonder if someone could provide some information on how this connection actually works as the misalignment does not seem to provide the opportunity to achieve a satisfactory aligned connection between these components... is there a reason why the smaller tie rod does not also attach to a spherical bearing?

 

[SaparotRob]

I have no clue but that rendering is cool!

 

[cammerjeff]

If I understand your question correctly, both ends of a control rod usually have a Heim joint that allows some movement on both ends of the control rod, so the rod does not have to be in perfect alignment to function thru-out its full travel. Each rod end had a Heim joint that allows inner ball end to swivel. Thus not bind when the geometry is not perfect.
I hop this answers your question. If not I am sure others with more knowledge will add to this tread.

Source - the web

 

[cvairwerks]

Hugh: What's the drawing number you are looking at?

 

[Hugh_T]

Hugh: What's the drawing number you are looking at?

There are various layout drawings that show this configuration similar to #237500 and #249131. The main attaching brackets for the flap are #238181 and #238180 which cover model variants E, F, G, H, J, and F5B which defines how the blue rod end tie is typically installed.

 

[Hugh_T]

If I understand your question correctly, both ends of a control rod usually have a Heim joint that allows some movement on both ends of the control rod, so the rod does not have to be in perfect alignment to function thru-out its full travel. Each rod end had a Heim joint that allows inner ball end to swivel. Thus not bind when the geometry is not perfect.
I hop this answers your question. If not I am sure others with more knowledge will add to this tread.

View attachment 715832

Source - the web

Thank you. That is how I expected the tie rods to be connected when I first started this study. Perhaps the attached images showing the exploded view for each connection will clarify.

 

[MIflyer]

I don't think I understand your question. As Cammerjeff says, the color drawing you provide shows an ordinary control rod with two rod end bearing, one at each end, that allows the rod to self-align. The control rods on my Ercoupe look just like that, although they use threads in the rod itself rather that the coupling barrel.

I do not see an AN200 in that drawing. See attached.

 

[Hugh_T]

I don't think I understand your question. As Cammerjeff says, the color drawing you provide shows an ordinary control rod with two rod end bearing, one at each end, that allows the rod to self-align. The control rods on my Ercoupe look just like that, although they use threads in the rod itself rather that the coupling barrel.

I do not see an AN200 in that drawing. See attached.

View attachment 715852

The AN200 is specified in the tie rod assembly drawings; that is a planar bearing. The essence of the problem is that at the default settings, the Track Carriage and the Flap are slightly out of alignment but as I said there is the capacity to adjust this carriage alignment, however, that is dictated by the top fixed connection. All the key interfaces are toleranced dimensions and depending on how this is manufactured will either give a reasonable alignment or not...I know I have spent a great deal of time checking this. To recap I am looking for details of the connecting nut #233021 and a question as to why the tie rod does not have spherical bearings at both ends.

 

[MIflyer]

So you assume that the other end of the control rod, the end that you do not have colored blue, has a bearing but not a spherical rod end bearing?

 

[MIflyer]

There is more in this section of the manual.

 

[Hugh_T]

So you assume that the other end of the control rod, the end that you do not have colored blue, has a bearing but not a spherical rod end bearing?
View attachment 715864View attachment 715865

I stated in my first post "This rod is attached to a spherical bearing to the carriage arm which gives it multi-directional movement...however, the smaller tie rod (blue item) on the wing flap itself is attached to a normal AN200 bearing which is not multi-directional." I also demonstrated in a later post a close-up exploded view of each connection.

I appreciate your assistance but I am not sure what your point is. There are no assumptions being made here...actually, as an engineer, I generally don't do that.

I have studied the manufacturing tolerances and adjustment parameters of the carriage arm and there remains a likelihood of a misalignment between the tie rods...so I am wondering why they did not include a spherical bearing on the small blue tie rod which would eliminate any alignment problems.