snewpy

I just put together a GWS F4U with a brushless outrunner with a 9x7 prop and a 9 cell NiMh pack. It flies well and is very fast compared to what I'm used to. At full speed it makes a very loud vibration-like noise. Kind of a "honk" sound. I can't tell if it's the cowl vibrating or something in the fuse or what. Anyone else had this problem, do they all do this? The foam really seems to amplify the sound. I installed the landing gear (many people don't) and used a single servo for the ailerons but decided to use straight rods so they work better accross the bend of the wing so they are exposed. Any ideas?
Darren

IFlySlowPlanes

Wait....did you say the control rods for the ailerons are exposed and extend from the fuse across the wing to the ailerons themselves? Is the control horn on top of the aileron then? If this is the arrangement, I think you can bet the control rods are the culprit. Although I can't imagine anyone doing this. i'm assuming I misunderstood your setup.

snewpy

No, there are no control horns with this setup. The ends of the rods are bent and glued into the center of the ailerons. Only a small section in the middle of the rod is exposed on the upper surface of the wing to "cut" the corner of the wing bend. You can't rotate the rod if you bend it to fit the wing. I could post a pic if you still don't get what I mean. They are very solid and won't cause much drag (much less than landing gear) so I don't think they're the culprit. I will try a few things next time I fly it like a different prop, removing the cowl, removing the battery cover. I just seems like it isn't meant to go that fast and is going to shake apart.

Jagzilla

Are you using a gws prop? If so, it might be the sound you are hearing is the prop loosing all its pitch and starting to howl. All gws props I've owned on higher speed brushless motors have done it. If that is the case, go and get an APC prop, and your problems are gone.
J

snewpy

It is a GWS prop and it is pretty flimsy. I'll try to find a better one. Thanks.