Weird noise! I know. I know but need help!

I had an rv with a noise that drove me nuts and I chased it on and off for a couple years. Almost sounded like sheetmetal sorta rattling against something. It would come and go but when it was there it would start at a slow speed like maybe 35mph to about 60ish and then quit. Finally found out that the problem was related to the galley sink trap that would sometimes run dry and with the air blowing across the sewer vent on the roof it would make this noise sorta like if you blew across the top of an empty soda bottle. The solution was to always keep the sink drain plugged with the stopper.

Look at steering axle tires for divots and flat spots on outside and inside edge, perhaps.

Sounds like metal on metal! Just to clarify, when you said it "it keeps same rhythm", do you mean in sync with speed or same rhythm regardless of speed?

sounds like the wind spinning up a fan that is not powered up like the stove hood fan or a fan behind the refrigerator

I did check to see if my hubcaps were loose but didn't think about the hubcaps rubbing! That would make sense. At low speed and when slowing down below 10mph the noise is at a slower pace then speeds up and stays constant till about 35-40mph and stops. Will give that a try. Thank you all!

Is the noise wheel speed? Do you happen to have hub caps that might touch the tires?If so.spray some WD around the cap on that side.

Looking at the floorplan, that's right around the right rear tire. I can hear the pitch change with your speed. Sounds like something rubbing on a tire.

Quick update. Checked all the exterior vents and nothing seemed loose. Checked for air holes inside and same. Noise is persistent and it is driving me crazy! I was able to record the sound. Please take a listen. The speed was pretty much from zero to 40 where the noise goes away sparatically.

https://youtu.be/atEeqGL8Poo

I had a strange noise when parked a few weeks ago. It was coming from the outside of the fridge compartment. Sounded like the cooling fan was hitting something. Got out the ladder and removed the the top panel to see some no longer sticky duct tape flapping in the breeze from the cooling fan.
Hope your fix is as easy as mine was.

Check for a loose hub cap on the rear wheel...