As they say in Brooklyn, ****edaboudit![&o] (umm... "forget" OK with auto-censor?)

But there are exceptions, such as Black Dirt Squadron. Home page [link=http://www.blackdirtsquadron.org/]here[/link] with a link to a video (on the home page) giving an aerial tour of the area. Lotsa room to open up and let 'er rip. And the club owns the land!

I am in process of installing the velo stack. I'll take a couple snaps tonight after I'm done and post here. The baffle is unusable

Looks like I will be able to choke the carb through the firewall by simply blocking the velo stack from inside of fuse. Obviously requires a hole in the firewall, which I already had in place. I'll have to wait until Saturday at the contest to see how it works

Thats unfortunate.   I modified it by cutting off the rubber tube from the foam insert (right at the base of the tube and removed enough of the rubber) and it slides right over the velocity stack.   Do think it is worth trying to increase the area of intake on the baffle.  I may give it one more try.  I purchased some Sonic Barrier 1/2" Acoustic Foam that I plan to line my motor box with.  I'm a musician and this is the stuff we line speaker cabs with.   It dampens the high frequencies out well.   But other than that I don't plan to pursue the intake silencer approach any further. 

By the way, my reason for using the velo stack has little to do with noise.....I've decided that the noise footprint is fine on my set-up. The 17x12 being turned at around 8K produces similar noise to the Webra 160 I was using.

The main reason I am going to use it (unless it totally bombs) is to keep the fuel spitting from messing up my fuse insides. If it helps breathing, all the better.

Choking will not be much of an issue. I have clear access from the canopy area to stick my finger on the stack and rock the prop. I abhor using the meat grinder on my spinner and generally hand crank. Of course, once started, engine starting subsequently is trivial.

Here're a couple photos. The choke baffle was removed and just as I thought, the stack fit is exactly where I can reach it. I just hope there is enough air getting into the fuse from the canopy area and firewall hole

The sunset was taken on the way home Sunday...NJ Tpke. Just happened to have my Nikon at the ready

I also shot the exhaust header. Header is holding as tight and as clean as when I installed it 3 or 4 weeks ago. Not a drop of oil goo anywhere to be found after a solid 4 1/2 - 5 hours of running. I think the exhaust situation is well under control

No, the engine was not re-cleaned before taking the snaps. That's what it looked like upon extraction from the fuse. Just love clean se-ups

Curious if you will have to richen your needles a tad and if you do the ol' Bernoulli's Principle is in effect. 

Bravo, Matt, you're really getting it tweaked and tricked!! A solid, clean set-up worthy of a fine airframe.

Will you get to fire it up today to see how the velo stack works before flying at Poconos?

My header is still holding tight as well, and still only few drops of residue after a long flying session. However, if the velo stack works I will probably get one to install, and while the engine is pulled I might take the opportunity to reinstall the header with some gasket material.

Maybe a tad, but that is such a short run it may not affect it at all. Perhaps that's why the stack has the angled cut, to increase the inflow area enough that it doesn't lean the mixture.

Well, Matt will know soon enough!

I am finding that I really do not need the choke most of the time anyway, with the accelerator pump carb, it starts by blipping the throttle a couple of times. This assumes there is gas in the carb of course! Hopefully, I will get some more time on it this weekend and see if the button heads, clamps and teflon tube from Cody allow me to fly it for more than a couple of minutes before the pipe blows off!
For the velocity stack, did you guys ever consider the OS GT-55 stack? I don't want to take off my Syssa right now, what is the center to center distance of the Syssa carb screws? I measure the OS carb screws to be about 1.25 inches c/c. Tower has it for $21.99 BTW.

Has the Teflon you are using been tested on gassers? Probably OK, but as I found out not all Teflons are created equal. Matt got the right stuff and I got the wrong stuff and it promptly burned out.

You will see that the buttonheads make a world of difference. Should not come off with the spring clamps, although there may be a little exhaust residue that makes its way out.

I am not sure, but it is what Cody is using with success (so far). I think he got it from McMaster-Carr.

I think I "talked" with Cody about the differences a few months ago. It should be in the Xtra 300 thread.

You want Teflon PTFE. Stay away from Teflon FEP and Teflon PFA.

DuPont is about the only mfr of these types of materials (fluorocarbons) that uses their tradename "Teflon" for all of their fruorocarbon lines...there are several.

They differentiate between the different types by also including the chemical name of the substance. Other makers of the stuff have different tradenames for the different chemicals

Bob,

I will try to squeeze out of the office a couple hours early today and head out to the field. I am very curious to see how this thing behaves. I suspect it's all smoke and mirrors stuff but we'll see.

On a dfifferent note, I mixed 5 gallons of gas back in March and still burning this stuff today. Regular auto gas isn't really as good after this length of time in the can as fresh gas is. I need to get some more oil but only will mix 1 gallon at a time from now on.

Not to mention that 5 months ago, it was a different blend, Winter gas is different than Summer gas.

The velo stack appears to be just as I thought...smoke and mirrors. Maybe there is some advantage on large engines but it doesn't amount to much on the 180. It mutes the reed sound some because it is located inside the fuse

One thing about choking the carb using the finger, it is much more effective than the baffle. Rocking the prop 15-16 times with finger choke, promptly flooded the thing.

I think it may only need 3 or 4 cycles and would be ready to fire.

At the contest this weekend I found I needed to open the canopy to access the velo stack practically every time I needed to start the engine. It needed one choke cycle and it would fire up pretty much immedietaly, but then I had to re-install the canopy....it was inconvenient.

With the regular choke baffle on the engine, it seemed that I didn't have to re-choke the engine but that could be because it was not idle for a couple hours between flights. Even if it needed choking, it was much simpler to actually do.

In my opinion, the velo stack just isn't worth the hassle as it is set-up today. If it also had some means of choking without opening the fuse up, then it would work fine. I think I will return to Todd's baffle set-up.

There was considerable interest in my set-up and Bob Moulder's. Several guys asked questions. A couple of them actually own the SAP180 but have not run it as yet.

Matt,

Jim Quinn also got the information about the SAP from me, so maybe there will be something about it in K-Factor.

It was interesting that just on the heels of our discussion about the keen interest in gasoline engines from Europeans and Asians the gentleman from Spain was very intent on getting the particulars of the entire set-up.

Did you try working the throttle a few times to squirt some gas in there, then try to start it w/o the choke?

Yes, I did but that doesn't mean it won't work for someone else. It didn't work for me.

Anyway, it was a worthwhile experiment to see first, what would the velo stack actually do regards to noise? Second, would it result in any improvement in output (power and throttle response)? Third, how user friendly would it be?

Well, having had 7 flights with it, about the only thing I noticed besides the choking, was that in both the 8 point roll and 4 point roll, the engine would burble as it entered the 5th point or 3rd point respectively. That is, when top left rudder was being applied. Very strange behavior that was not there when the engine was set-up with factory baffle. I don't know what to make of that.

There was no improvement to power output. No improvement to noise either. Fuel spitting got on the tank, almost a foot away from the velo stack. I now have two velo stacks for sale....cheap. And one intake muffler even cheaper

Oh well, it was a worthy experiment. As we said at TRW, 1 test is worth 1000 opinions! A foot away, wow, I am glad I added the additional firewall at the end of the engine box.

Ok, I finally got around to flying, and when I got home I wanted to adjust the throttle curve. I rigged up this ultra sophisticated dyno/thrust rig made from a dog leash and a fish scale. What is cool is that I got it so at about 1/2 throttle, I get just a little more than 1/2 thrust. It should make it a little smoother and besides, that 1/2 throttle is just about the hover thrust, i.e. 12 pounds of thrust. The max thrust was 22 pounds, 15 oz with the 5/8 spacer between the header and the pipe and a Vess 18-6, but that is what was indicated, and I know there are losses in the wheel friction, ground effect, and a bunch of other things, but I think that is pretty good anyway.. Nothing came off, but my red anodized header is now pumpkin orange, but I figured that would happen. The M5's on the header flange with the Nordlocks are tight.


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Probably about 95-98% as accurate as an engineering-grade unit.

You probably already know this, but it's better not to run the engine too much with the wings off the model due to reduced mass damping.

But that is one schweeet lookin' model! The tuned-pipe stinger sticking out has a bad-ass look to it. [sm=thumbup.gif]

Thanks! But that brings up a question I have. Can I cut off some of the stinger without suffering engine performance?

Todd cut his shorter. I didn't want to cut it so I used a rubber grommet on the Dave Brown mount instead of the sandwich mount that was provided and it got me another quarter inch or so into the pipe chamber. A dremel with a carbon wheel will do the trick. The dogs don't appear to be too interested in your plane. No decals, looks good. I have been out a motor for four weeks now...hope to get it back soon.