1967brutus

You can't get more Cub-ish than a Bobber...

I mean, if Disney ever would do an adult version of "Planes" the Bobber character would be hanging of a polished pole in a sleazy bar...

Glowgeek

Re compression ratio: What Bert said. In addition, with 4 strokes, there can be a great deal of difference in static (calculated) CR and actual (dynamic) CR. Some of these little engines have racey cams.

That said there are some Saitos with very high CR (over 13:1) that would likely need some taming with a cylinder shim to handle well on gas. The high compression fa65 (version 2) and the fa150 (version 1) come to mind. Both prop chuckers on methanol even.

John_M_

You know the American ways too well Bert ... I do like the Bobber over the Savage Shock Cub... Zlin's got one in 1:3 and 1:2,5 scale, big enough to put a Valach 140cc twin boxer up front... 210cc in the 1:2,5 scale

https://www.zlinaero.com/prodotti.php?id=13&lang=2

1:3 Scale

1:2,5 Scale

Raleighcopter

i managed to install and play with fusion 360. here's my first attempt at a sensor ring for my magnum .30. just need to add a couple holes to clamp the ring at the gap.

1967brutus

Cool. is going to look good on that engine.

John_M_

That's not bad Raleighli' ... but the idea with 3D printing, you can get a bit more creative, Like adding a wire support strain relief with an all in one coffee cup holder ... just pulling your leg... I take it the hall sensor will fit in a recess where the rectangle protrusion is, from behind of course.

Raleighcopter

that is the plan. i modeled that protrusion to be hollow. the magnum 30 only has a 7mm space for the strap and the prop hub is also only about 7mm thick. the plan is to eventually share a parametric design where a user could simply change a couple dimensions and have a working bracket for many different engines.

1967brutus

Yup... It's tiny, innit?

Cat 1

My Feedback: (1)

Dave - Went looking for my sensor mount and can only find the working version that was not complete - I must not have saved the completed version or I have hid it on myself - Here is how I did the mounting - this is just the ring but it might give you an idea of how the tightening bolt is arranged - The ST .45 was a "skinny" mount too.



I will send the Fusion file in an email as it won't let me attach here...

Will keep looking for the other files

cmulder

Got the first pico pies in. Soldered pins and started to look how to program them.
Folowed the steps on the raspberrypi.org site and got this far.
So right now the pi and computer (pi400) are talking to eachother using thonny.
And pin 15 is working as output.

I know this is pyton and not c++ so the next steps will be getting the arduino ide talking to the pico.

Btw my programming skills are beginner or worse....



pico pi blink led

Raleighcopter

Download my code and read it. Ask questions. It won't run without modification on that platform but shouldn't be too difficult to port over.

cmulder

That savety nut is there for a reason.
My "starting procedure" is to close the choke, spin it by hand until its almost flooded, connect glow power and then bump it against compression clockwise with a chicken stick.
Vicious S.O.B.

goldberg piper

cmulder

Its fun challange.

Thinking ahead a little since the pico is 3.3v and recievers are 5v, should i get one of these;
voltage-level-translator-breakout

Glowgeek

Yessir!

Saito did a weird thing with the FA65. Version 1 had a fairly high CR and they raised it even higher on Version 2. Then they reduced the CR for Version 3, below what Version 1 had been. Version 3 became one of the sweetest handling Saitos ever produced. I've had all three at some point in my journey. Off topic, sorry.

Raleighcopter

You should check the datasheet but if you're only reading 5v channels and not sending data to the receiver, you can use a simple 2 resistor voltage divider (4k/6k resistors would work).

cmulder

Got the arduino ide to upload the "blink" sketch to the pico.
Again using the p400 and there 64bit os.
On my mac 10.12 there are pyton version (use 2 has to be 3) errors while compiling.
Not going to risk messing up my mac with upgrades that might break other programs so stick to using the p400.
One anoying thing is that you have to press the buton on usb-connect to set it to its
program mode each time you try to upload a sketch.
Also deleted any program files that thonny put in its memmory since that appeared also to make the arduino ide refuse to upload.
A new unused pico does not have that issue.
Next tomorrow is to make a image backup of the p400 so i have a return point when i break the os again.

So Far so good..

cmulder

[QUOTE=Glowgeek;12739031. I've had all three at some point in my journey. [/QUOTE] Got mine new around 95. Are there any markings to se what version mine is?

Glowgeek

Version 1 and 2 had the matte finished rockers (as shown in your pic) and airbleed carbs.

Pull the glow plug and take a peak at the piston top. If it has a center hump between the valve reliefs it's the highest compression version (version 2), if not, it's version 1.

These links should help.

Saito FA-65
Saito FA-65 (2)
Saito FA-65 update model

Cat 1

My Feedback: (1)

Got out flying tonite and got to try the Skinny bore carb on the ST.45. Magic!!! - Power might be down a bit, but I propped down to a 10X6, got the revs up and I think it as powerful as all but of a few of the .40 size glow engines I use to run. Not typical .45 power but a good solid sport .40 performance. Throttle transition is great and great response from long extended (cool right down) idles. Got some video but haven't processed it yet - It was super windy and I have to take out some content so you all don't think less of me ..

All in all the bore reduction project was a successful experiment in my books - Took away the need to leave very rich to insure good in flight mixture - I'm still on the rich side and sneaking down slowly as I'm a bit gun-shy from the big bore setup.. mixture is very "non-critical" now - still a little touchy around idle but very much improved.

I did notice one thing while playing with idle mix - You must be on the rich side of the "curve" almost to the point where you think it might be loading up a bit. When the engine is hot (just throttled back) it might seem a bit rich and leaning helps it run "better" but as the engine temp drops it need the extra fuel to maintain idle. Its understandable - but not an effect usually noted on a glow engine.

1967brutus

Over on RCG, user AA5BY reported having a couple of Saito's he had shelved because of their very nasty starting behaviour (vicious backfiring and fingerchopping) that after conversion to spark and gas became *****cats to get going...

1967brutus

I so far never have tried the bore reduction thing, but I can imagine its advantages. Motorcycle manufacturers play with carb bore sizes all the time to adapt a given engine to its intended use (same engine in a sportsbike or a cruiser, they ARE going to have different sized carbs/injectorbodies).

Bit amazed about the "idle mixture thing" though. So far, my experience has always been "as lean as i can get it", which for the singles is not so much an issue, but the twin and radial, due to their residual uneven mixture distribution can be a bit tricky to find, because one cylinder remains a bit rich and tending to load up while another tends to lean out and stop firing. So far all has been doable and even reliable (both Radial and twin have never quit in the air OR on the ground) but never as easy as a single. Also never been really problematic.

Cat 1

My Feedback: (1)

Here is video from flying last nite - Sorry for the flying it was a very "solid" wind and the Kavalier is not the best windy day machine.. engine ran the best ever.. still a bit on the rich side in a couple of the clips.

Two things of note -
It ran forever on 4 oz of fuel - With the video I took it was over 18 minutes I think. I was trying to "run it out" but then the wind picked up more and I decided not to tempt fate and end up on a long walk. (got tired too) I'm sure I could easily fly for 30 minutes at reduced power settings.
Its running very clean now - Residue is very light and very transparent.

Cat 1

My Feedback: (1)

Its not so much a problem Bert as it never "quit in the air" on me, just an observation - I just noticed it while tuning the idle on the bench. Once the engine warmed up my idle seemed a little thick, so I leaned it and it cleaned up - then on an "extended" idle it would suddenly die. had to go back to the slightly richer setting.. Not really noticeable in the air as I think the airflow pulls the temp down quickly and gets it in the happy zone. With the smaller venturi I am back on the bottom for the entire fuel curve again - I will try a smaller jet and see how it works. - but its running great now.

John_M_

Engine sounds good... I have a Sig Kavalier as well as a Komander mkII, never got built... nice airplane, but a bit too nimble for my old eyes... Have a Headmaster Sport 40 kit as well.

1967brutus

Ah, OK, yes... The way you describe it, is still conform how I do the "as lean as I can get it". As long as it idles indefinitely it is OK.
The fuel consumption sounds about right: I could get about 45 minutes of "very spirited flying" out of 8 oz of fuel with the OS FXi 46, and easily when used for for example flight training (puttering around at half throttle doing the figure of 8's and squares etc, it would typically consume approx 1~1,5 oz/10 minute session