Rubbing fan

[xmech2k]

Sorry if this belongs in the newb forums, since I'm a newb tro EDF's, so plz move if necessary.

My story: I just rcvd my Dynam Turbojet today , but while unpacking and spinning the fans a little(by hand), I noticed the RH fan rubbing. Closer inspection showed a very worn area where the fan rubbed the duct pretty bad. You can easily feel it with your finger, and it's at least 1/3 the circumference of the duct.

I called their support, and they wanted me to e-mail pics of both fans, and they'd send me a replacement. So when I go to take a pic of the LH one, i see it has rub evidence almost all the way around, but you mostly can't feel it.

From stuff I've read before, I thought EDF's shouldn't rub at all. Are both fans bad? Can someone educate me on this?

I searched and couldn't find anything on fan rubs here. I'd post my pics here too, but I'm having trouble with the uploading.

Thanks guys!

[tampaflyer]

fan rub is common. as long as they don't shake from imballance.
as the fans spin the blades expand and some times rub. the closer to the duct the better they perform. even the glow d/f had rubmarks.

even minor chips/nicks will not over all "hurt" the impeller.
sucking everything through them will.

[xmech2k]

Thanks tampaflyer. That gives me reassurance on the LH fan at least. That RH one is so deep though. I'm working with the vendor I ordered it from now, and I mentioned how I found the LH one as well, and asked if some is normal. Haven't heard back yet. I'll see what they say. The spare parts list has the fan and the duct listed for like $3 each, maybe they'll still send a new one.

It's obvious the RH fan is not centered well, I wonder if there's an adjustment I could make. I don't recall seeing an illustrated breakdown. I'll have to solder in a dean's connector to test it, so I guess I'll see what they say first.

[tampaflyer]

rubbing , maybe... not gougeing.

that is the problem with cheaper fans.. no quaility control. good news is that the fans are cheap. but digging them out of the foam can be fun.

[4stripes]

Usually an imbalance will cause the rubbing. I've had a number of fans that had half the motor mounting screws missing. The 64mm fas are often only held in with 2 screws and not the 4 possible. Take the spinner off and check. Once the mount cracks from being held on with only 2 screws, you will lose the fan with flexing.
If all is secured properly and you feel that it runs smooth, don't worry about it.

[xmech2k]

Thanks for the info, guys. I found a breakdown in the manual, and would have torn into it already, but I think I'll wait for customer support a day or 2 just in case. Hopefully, this doen't turn into one of 'those' stories...

[xmech2k]

They e-mailed me back and also said a little rub is to be expected, and will send me a replacement for the bad one, so that seems to be working out well. There is a parts breakdown for the fan and it doesn't look bad at all. The 'cowl' looks like it just has screws holding the halves together, so hopefully there isn't much digging to do, as tampaflyer mentioned.

Now I have to sort out pic uploading so I can post some pics of this good looking bizjet. Don't know why it's not more popular, other than people wanting military stuff more, I guess.

[tampaflyer]

had the big one flew great

[4stripes]

Forgot to mention, insure nothing is distorting the shroud circular shape in its mounting area. A little squeeze can distort the shroud enough to cause problems.

[xmech2k]

Thanks for the tip, 4stripes. Didn't think of that one. I'm hoping I didn't jump the gun going to an edf. I think I'm doing all right with the props, especially with that Phase3 P-40. I've upgraded the motor so it can actually fly(Also just went from a 10x6 prop to 9x7.5, to get some more speed, I have yet to fly with it), and after my first tip-stalling landing attempt with it(With the original too low power system), I always keep the speed way up when landing.

Tampaflyer, I didn't know there was a 'big' version of this one! Although your pic looks like a wood built-up version. Looks similar otherwise, even the flaps. Thanks for sharing.

[xmech2k]

Well, 4stripes, you were 1/2 right. I removed both fans from their nacelles, and neither eubbed, when I didn't give them a little squeeze! Although the RH one is still obviously not centered. So I reinstalled them carefully, and now the LH one is fine. Ran to full throttle no problem. The RH one is still no good. The fan units came out pretty easily, but the fan itself doesn't want to seperate from the shaft. Will try more tomorrow. Thanks again for the tip, 4stripes!