Lower side frame broken often....

[mplourde]

Hi,

I want to know if there anybody have de same problem on Raven/Falcon/Hawk heli.

On my Falcon, it's the third set of Lower side frame I changed this summer because they crack on the corner of the " L " form, at the back. :? Ok, maybe some Autos was a little bit hard but god, not to broke my Lower side frame.

I think it's a bad design from Century. Having a plate to put below both lower side frame likes Predator should relsove the problem. Need a hop-up Century!!! Please... :roll:

[trace]

Yep, hard autos are the culprit. Bends the L even more and then vibration finishes cracking it for you. One way to stop it is add a small angle piece which parallels the strut but spans from lower frame to lower frame and picks up the strut attach fasteners. No need for a full bottom plate.

[SteveH]

You are right, over time they will break on the bend, especially on the 50's. However, I have found a cure that virtually eliminates the problem...fabricate a spacer that goes between the two bolts that hold the boom supports. I'm using plastic from old broken landing gear now. The older Falcons and Hawks used a one piece boom support and it had a spacer between the frames there and I used to use them also, but ran out of them.

[RAV50]

Seems like Steve and Trace have a similar solution. I have used both and they both work. Mind you I find that, like Trace, I prefer cutting a small crosspiece of aluminum to fit between the top of the landing gear struts and the lower sideframes, running from the left side to the right. This is how my old X-Cells were set-up.

Just to stiffen everything up I use one on the front strut also.

[tailboom]

I do the same as I have JR vibration dampners between the gear and the lowers. It also helps to prevent fuel foaming.

[mplourde]

Thanks guys for your reply. So, if guys could please send à picture of it to understand well what you have done, It's well be very appreciate!!

Thanks,

[tailboom]

sorry for the quality of this pic. but you get the idea. :wink:

[mplourde]

Thanks for the pic. But, my lower side frame crack on the corner at the end. Click on picture and check where the red circle. Do you think this can relsove my problem??

[tailboom]

Thanks for the pic. But, my lower side frame crack on the corner at the end. Click on picture and check where the red circle. Do you think this can resolve my problem?? You might also add the JR landing gear vibration dampeners like I did as well as the spacer. Heavy duty landing gear will also help.

[mplourde]

OK, thanks guys!!! I will work on it!!!

Thanks for your support... :cool:

Regards,

[Rckrzy1]

My pmax kept doing that and now I have a CF frame, got tired if replacing the same pieces.

[mplourde]

But, on Raven / Falcon 50, we haven't lower side frame in carbon pieces. It doesn't existe...

[RAV50]

As with any ali framed heli, it is CRITICAL that the bottom of the lower frame is aligned in all planes with each other. This insures there is NO preloading happening which will always bring on metal fatique cracking.

So before you tighten down all the bolts involved on each side (4 on upper frame, 4 on engine mount, 2 on servo frame) place the heli FLAT on a plate of glass or something similar, and insure the bottom of the each frame lies flat on it. Then tighten them all down and remove them one by one and apply appropriate locktight and reinstall.

You will find that the frames will last a LOT longer. And adding cross braces across the front and back of the frames, between the bottom of the frames and the top of the landing gear struts will insure 100's of flights with no cracking. (I have one with over 400 flights on the original frames.)

[mplourde]

What's the piece of cross barces are you using ? Is it home made??

[RAV50]

I make the crossbraces from two flat pieces of aluminum (85mm x 15mm) with 3mm holes drilled on each end at the spacing of the bolts for the landing gear.

[tailboom]

I took the top front brace from the Raven front servo support, and cut off the excess, then machined (using a drill press) the ends to 90 degrees. If you do this you must note that holes in the ends are not the same depth, so you might have to take off more on one end. I first screwed in a hex key collar screw to lightly bottom out inside. This allowed me to chase the threads after machining it. Be sure to measure very precisely.

[jko1]

Hi mplourde
Carbon lower side frame in carbon pieces. It does existe...
I just bougt some in USA. :wink: