Matt, a lot of guys will be happy in the spring for the accurate tuning info and tweaking you're doing now!

Stretched the pipe by 3/8" and that, combined with leaner low end, eliminated the jumpiness at 1/3 throttle.

This is a big development. I was kinda worried about that because mine jumped pretty big thereabouts.

the distance from the plug CL to the end of the pipe (not including the stinger) is 33 1/2" straight line. That's approximately 27 1/2" plug to baffle.

Very handy number, so we don't have to stick something down the pipe to figure out where the baffle is.

Top end rpm is higher than my ear perceived originally...I tached it at 8200 after the changes. Pretty terrific!! Throttle response is now about as linear as anything I've played with before and with the amoun

The thorobred can be tamed. Excellent developments.

Bob, thanks,

I want to make sure that folks get the fact that these numbers are true only for the ES 30G pipe. If someone has the ES 40G or the smaller 26G, the numbers would be different to the end of the pipe. BUT the numbers to the baffle should be very close to what I've determined so far on the 30G.

The Mintor aluminum pipe for the 37 cc engine has the baffle at very similar location to the ES30G. I wish I would have held on to that pipe. It would have made for good comparisons.

Matt

Great news! I like what I'm hearing.

MattI'm one of the guys who will benefit from this very important info. Thanks much for your willingness to share your experience which helps guys like me.

No problem Dan, that's the reason Ed and I went to Todd's place to begin with. Engine is too good not to share the info. Glad to do it.

About the only negative, and pretty slight at that, was a fuel draw problem during start up, early on, that Todd fixed for me.

I suspect that when folks see the whole set-up up close and and see and hear it perform, there will be more interest.

March and better weather is around the corner. Need flying info in a pattern setting

Matt

I was hoping to run my SAP 180 this week end, but we got hit with 6 more inches of snow with a couple more inches due Saturday, so I can only look at my engine. But I hope to get started on my Focus II this week end. About the fuel draw problem, was it only when you were starting the engine ? And what was the cure ?


Thanks, Dan

Yes only during start up. There was a problem with something being blocked in the carb. Once the carb was cleaned out, starting has been pretty trivial

The better method to draw fuel is to rock the prop between TDC and BDC, as Todd recommends. If you smell the gasoline there is enough fuel in the carb to start. Usually takes two or three flips after the carb is primed, and it's running.

Matt

How did you go about cleaning the carb ? Did you have to remove it from the engine ?


Thanks , Dan

[/quote]


How did you go about cleaning the carb ? Did you have to remove it from the engine ?


Thanks , Dan
[/quote]
Well, normally that's what you would do. I didn't know that at the time so I sent it back.

Matt

Dan, glad to hear your Focus assembly can get underway, even if the engine running will be delayed a bit. Oh boy, doncha just wanna crank up that little jewel??!! We also got about 1.5 feet of new snow... sloppy, wet stuff. At least crappy weather encourages us to stay indoors and build.

Speaking of which, my best advice on the Focus II is to place the fuse on a very flat work surface and insert the wing tube, then cross your fingers that the fuse is fairly straight and that the wing tube socket is square with the fuse. I had no such luck with either the Focus Sport or the Focus II, but along the way I figured out a sequence of assembly to ensure that at least the fin, stab and wings come out square/perpendicular to each other, and a quick fix for a crooked wing tube socket. If you are super-anal about having a straight fuse, you'll need a combination Medieval rack/Japanese steam bath to straighten that puppy. I decided just to cheat a little.

Maybe everything will be straight and this will all be moot.

I don't want to stray too far because this isn't a Focus II thread, so if you wish, PM me after you've laid out the pieces and figured out what the heck you're up against. But when actual work begins, you want to do the engine mount and pipe tunnel first. And then the STAB. More on that later.

Just keep thinking all the while, there is a damn nice flying model at the end of the process, and it's okay to cuss while you work.[sm=what_smile.gif]

Nothing wrong with a little building advice. FWIW- I always set the stab to fin relationship first....it's as important a relationship as building flat surfaces. This needs to be as square as possible...even a slight misalignment of a couple degrees will affect flight precision. A simple way to do this is to make a large isosceles right triangle template from 1/16" lexan sheet. Scribe cross-hair from the right angle to the hypotenuse and also scribe a series of parallel lines to the hypotenuse. Make the cross hair as accurate as possible, not to belabor the obvious. Anhedral stab? No problem with the template

Then carefully drill 1/32" holes on the lines such that the template may be pinned onto the fin. The stab needs to align with the hypotenuse parallel lines. I prefer the template because things are held in place while the glue dries. Also, the template should be large enough to serve to prop up the fuse on the work bench while the glue dries. Always a good idea to check fin and stab CL's with a cross laser, making final adjustments as necessary.

The wing socket in the fuse often has to be adjusted to square everything. One should never assume that the factory placements were correct. My current design on the building board started out as a Brio fuse. Once the stab was set, the wing socket in the fuse had to be adjusted 3/32" to get the stab and wing parallel. Unfortunately, factory installation of wing adjsters and all the holes cut for servo wires and such all had to be filled and redone.

I've had to do these adjstments on all composite fuses I've build so far from, cheap to expensive, from Piedomont models to ZN Line.

Matt

Bob, "It's OK to cuss while you work". I already started cussing, and I'm off to Home Depot to find a Medieval rack/Japanese steam bath. As usual, thanks for your valuable input.

Dan

Matt, Thanks for your valuable input. Appreciate it.



Dan

Matt,

Your method is definitely a lot more accurate than mine, but I can't quite envision the template from your description. No rush, but if you have a photo that would be nice. I've found myself more than once thinking '"There has got to be a better way to do this!"

Now, I measure-eyeball-measure-eyeball, and then repeat that about 20-30 times, then have my wife come take a look at it and do the same thing before gluing anything. Pretty good so far, but I always breathe a huge sigh of relief when everything lines up, because it isn't exactly a sure-fire thing.

Yup...that was mine as well, until I came up with this technique.

I re-read what I wrote and I see it wasn't clear. To visualize it, take a piece of square paper and fold it diagonally. You now have a right isosceles triangle. Fold it again, bisecting the right angle. You now have the makings of the template.....open the second fold back to the original triangle. The second fold line is the vertical that attaches to the fin. Draw a few lines parallel to the hypotenuse (the bottom) and you have a scale model of the template. Note, the vertical fold and the parallel lines are perpendicular to each other

My original template was made from cardboard which worked okay but was not transparent and was a little too flexible. Lexan of course, is transparent and has about the right flex. I'll take a snap tomorrow and send it to you

The technique requires careful scribing of the fin's post and stab's elev facing. But if that's done accurately, fin to stab alignment will be within 1/10 degree and probably better

Matt

MTK if you can please pm one for me to. And a few photos of how it works I'm new to this and wont to see and learn.
Thanks Bill

Matt, Ditto. One for me too pretty please.

Been looking fo the template; haven't seen since the move 5 years ago. Guess what? I finally found it but it has a break on one side. Oh well...it will still convey the message I want. I'll post a photo or two tomorow

Matt

Thanks, Matt.

Flying today??? I am always awaiting further data!

I hope to get out later today - I have been looking forward to lengthening that coupler getting some serious tuning and trimming done.

Bob,

Ed and I are planning to head out sometime today. He has his Aquila ready with SAP up front. Mine is down at the moment...Enigma test bed was dismantled temporarily to do some bench running with different props. Just hasn't been practical to work with the whole plane in the garage.

On bench running, discovered that the spring in the spark plug lead had been sucked back just enough to cause some misfiring. I don't remember this engine ever missing a beat except on low battery when running the the test bed, so I must have done something to the wire when removing it from the plane. Todd is on it.

The last data I have is running the 18x12 hybrid prop. I'll take the prop with me so Ed may try it on his set-up. Well, on second thought, I don't think Ed put a pipe on the Aquila so I doubt if the engine will turn the load unpiped, but we'll see. Ed also has the 19x10 hybrid...it will be interesting to see how the engine turns this prop. On my piped set-up, you may recall, the 19x10 turned up around 8500 in the air, ripping the air loudly. Without the pipe, it may be just right.

Matt

Guys,

Here are a couple photos of what I talked about. The triangle is actually an obtuse isosceles such that the large side could cover the stab's elevator facing.

I can only upload one file at a time

and one more. The lines are carefully scribed with the back of an Xacto blade to make a shallow groove. Then I used crayon for the color and contrast

We finally got a break from all the cold & snow, so I flew My SAP-180 today. I'm starting out a little differently through the break-in period, using the stock muffler while I get to know the engine. My main reason for doing that is to make sure I have a good handle on baseline performance and behavior before adding the pipe. Using Lawnboy ashless at 32:1 and an APC 17x10 for initial runs. My engine is the one that Todd Syssa made some minor mods to, effectively reducing exhaust timing by a couple of degrees. Compression is just a little higher than the stock engine. Overall, it's not much different.

The engine started very easily the first time, and every time afterwards. Initial start using the prop rocking method with an open throttle and closed choke pulls fuel to the carb very quickly. Subsequent starts for the day never required any choking and were 1st flip events every time but once (I experienced a 3 flipper). It was necessary to open the high end needle about 2/3 to 3/4 turn from the factory setting to get the type of setting that I like for break-in. Temps were in the high 40's.

Performance pulling an Aqulia was very good, using the Masters sequence to gauge things. With only a 17x10 break-in prop, the engine unwound nicely in the air and had good throttle response all around. It died a couple of times in 2 1/2 turn inverted spins, I think because I set the idle too low for an engine that has not yet been broken-in. I had set it for about a 1500 RPM idle, so being set rich, running in cool weather and so forth, I'm not suprised that it quit at that setting in a spin. A couple of clicks higher and it was fine. Top end RPM was 8200 to 8250 after 3 flights. I recall from when Matt and I did the initial tests at Syssa with a pipe, that this 17x10 prop turned 8900. It's certainly a light load for the engine, but that's what I like to do when an engine is new. All-in-all, I saw some improvement through the day as running time increased. Compression is very good, and the engine now doesn't have that tight feeling like it did out of the box.

Can't wait to get the nose ring and try this in my Prestige.

Thanks for the photos. I can see how this would help remove a lot of the guesswork!

Ed, glad you got to fire up the new engine and fly!

Unfortunately, I was not able to fly the Focus yesterday because of snow cover remaining at Black Dirt. Had to go to work this afternoon, so I was only able to fly a small nitro plane locally this morning. What a waste of nice weather, ugh.

How was your soft mount without the nose ring? I assume you are anticipating the Syssa nose ring protoype for the Prestige... Will it work with a stand-alone cowl like the Focus has, or must it be used with a chin-cowl design?