Greetings,
I have an LT40 ARF. The covering wrinkles or smooths based on the weather.
Does it matter if the covering is wrinkled in places if you are going to fly ?

thanks in advance.

The wrinkles will have very little effect. Don't worry about them too much. Sometimes... its better to just not mess with it.
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If you REALLY want to get rid of the wrinkles.... You can take a household iron and get most of the wrinkles out.

If it has the self-stick covering (I think that plane does...) then the covering will not handle heat well... but it can be carefully shrunk a little. Start down in the delicates area... and be careful. (test on the TE of the aileron... where if you melt the cover it won't be a disaster. Hold for 5 sec, and if its going to melt... it will.)

If it has Monokote... you can set the iron right at the steam line with most irons. (start a little lower.. and if it won't shrink, turn it up a little.)

Wrinkles don't matter too much. Technically, there probably is a bit more drag and the aerodynamic are slightly effected, but not enough to notice except maybe on high performance planes.

Yes, weather changes will cause wrinkles to come and go. Typically after some time the covering will stabilize and the wrinkles happen less often and with less severity.

In short, minor to moderate wrinkles really don't effect a planes flight much. HOWEVER, loose edges can seriously effect flight. Be sure all seams are sealed, i.e. the covering is attached at the edges.

If it's monokote a heat gun would probably take those wrinkles out.

Don't worry about the wrinkles.... Just like skin, you will get them with age.
MOre exposure to the sun makes them more pronounced and more frequent.