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PostPosted: Mon May 03, 2004 7:37 pm
by nightwave51
I'm not in possession of my Lazair yet, so I don't know exactly what the velocity stacks look like. I don't have any tube flairing equipment in my shop but could probably produce the jigs if needed ( a lot of work). I could investigate contouring some out of solid stock - a bit of cutting but rock solid results.

PostPosted: Wed May 05, 2004 7:39 pm
by nightwave51
The 90degree flair at the end might be a bit tricky without stretching the aluminum to the point of fractures forming - the correct alloy (and heat treat) would be critical. It is definately doable - just a matter of getting the correct approach to the problem. I'll definately take a close look at these when I get my bird in July - might be a good fall project.

PostPosted: Thu May 06, 2004 1:01 pm
by Born2Fly

PostPosted: Thu May 06, 2004 1:27 pm
by Born2Fly
ok Velocity stacks,
Check out this place

EC-302VS b Ram Flow Veloctiy Stack for HL-227, HL-314, and thru HL-336 B $12.95 ea. 1 $12.95

Good Luck

Also - use tube -- spin the flange and tig it to a base plate to carb.
don;t forget to indent the tube before welding for the screws.

Hope this helps you guys.

PostPosted: Mon May 10, 2004 8:20 am
by b diedenhofen
I installed my backing plates from aerocrafters, last week. I used a dial guage to center them as per their instructions and had both mounted in less than an hour. The process described is pretty straightforward, and with a bit of patience, the plates are nicely centered and the spinners are true with no wobble. The plates themselves appear a bit thicker than the originals so they should last a little longer. Most spinners, on larger applications, have an extra mounting disk forward of the prop to stabilize the spinner. I suspect that this is the primary reason why the Lazair backing plates fail. It's virtually impossible to be certain that the spinner is completely balanced. Even a very slight imbalance at high rpm will, likely, stress the backing plate and develop cracks over time. Check them regularly, as part of the normal pre flight. My original plates lasted for a very long time before they failed. Interestingly, they both failed at the same time.


PostPosted: Tue May 11, 2004 11:54 pm
by Chappy

Tonight, while digging through my old Hill-Chase Steel catalog to make up an order of steel tubing from my local steel yard, I found that H-C sells (sold?) 1 .125 OD, 0.058 wall 3003-H14 seamless aluminum tubing. I'll bet this is what my shinny new 20 year old velocity stack is fabricated out of. 3003 is described as a non-heat treatable alloy with excellent forming, welding and corrosion resistance characteristics, used for deep drawn and spun parts. It's stronger that pure 1100 aluminum. It holds a polished surface well too. 3003-0 comes with an Alclad like coating, but I think that material is only available in smaller coiled tubing.

Now the challenge will be to get some to play with. BTW, Hill-Chase listed it only in the .058 wall thickness for 1 1/8" tube. Maybe your stacks were made out of annealed 6061-T6 tubing.


PostPosted: Fri May 28, 2004 9:56 pm
by Chappy

I found the original Ultraflight carb stacks from my Pioneers! They are two-piece: a straight tube welded to a flat baseplate. I have no idea why they have holes drilled through the tubes, unless it was to attach the throttle cable housing. Not elegant, but they worked.

One of my old Rotax velocity stacks, like the one in your picture above, still has the red making on it, and I suspect it was 6061-T6, as you have thought all along. I had never polished this one. You can see that a fair amount of heat was applied to it during forming, which you would expect if it was formed from 6061-T6.


PostPosted: Sat May 29, 2004 1:45 pm
by Lazair_guest_please_registershan
Hi Chappy,

Wow, those Pioneer stacks are crappy looking but as you mentioned they work.

YES, it does look as though the OEM 185 stacks are made from ordinary heated 6061 T-6. Exactly what I suspected all along.

Awaiting further details but it is all together possible that some NEW OEM reproduction 185 stacks will be forthcoming and available in the near future.