1967brutus

Awww... you've got one of them cute .30's... Those are the ones I am the saddest about dissapearing... Cute little sweethearts.

1967brutus

Meanwhile, in the Netherlands:


Clubmate Rob and his dad inherited an old long time unused OS FS40 (one of OS' first fourstrokes smaller than .60, so really an oldie, according to OS' timeline introduced in '81).
They also picked up an old unused Robbe Charter for free, so basically for the cost of a set of bearings and the conversion (ignition, solenoid-stuff and telemetry stuff) they had this very nice summer-evening-flyer.

From first start on gas to adjusted curve took them about 20 minutes of runtime.
Prop is an APC 11 x 6, initially engine peaked at 8100 RPM and was tuned down rich by about 300~400 RPM, so 7700~7800 on the ground.
After about 30 minutes of flying and groundrunning and general messing about, the engine all by itself gained allready 200 RPM and was hitting 8K on the ground despite its rich pre-flight setting.
Absolutely not bad for this old girl, and plenty power for the 60" winspan, 4.6 lbs trainer.... Yup, that is right, This plane, despite the "complicated and heavy conversion" weighs exactly what my own Charter back in 1982 weighed with a .25 glow engine in the nose...

Glowgeek

Nice old design, Bert. Flies great, sounds great. There's something to be said for relaxing Sunday flyers. No adrenaline, no knee knocking and trembling hands, just smooth sailing and sweet aero-bliss.

I've always been a push it to the edge kind of flyer. Never really understood the attraction to slow floaty flying, until I built this a couple of years ago.

1938 Sal Taibi Powerhouse, 88", 4.2 lbs, Saito 56, Osaka Silk

1967brutus

As you have figured out yourself, judging by the shiny Saito on the nose of that Taibbi design, the appeal of a slow flying plane gets greatly enhanced by the sound of a fourstroke...

Glowgeek

Slow flying, fast flying, pattern and 3D. I still fly one 2 stroke glow, just for nostalgia's sake.

By the way, that Powerhouse won at the FF nats powered by a "complicated and heavy" gasser. Lol

1967brutus

Damn right it did!

Cat 1

My Feedback: (1)

Beautiful Lonnie!!! - I have always had a floaty one in the hangar as on those calm evenings its so nice to fly and just "assist" . Touching up the path and bringing it back when needed..

Also beautiful!!!! I had an older OS .40 like this and should have never sold it - Even on glow it was a sweetheart. Found a similar vintage .60 that needs some attention, but will re-identify as a gasser when I get a chance

Rcplanedan

well with dremel carefully applied to the throttle barrel this brilliant twin cylinder was so easy to find a lose setting to get up and running..im amazed how easy the engine was to get started..and will hand start after stopping it

1967brutus

Dang, Dan! You're getting the hang of it a lot quicker than I did back then. Runs beautiful!
And indeed, they start extremely easy.

Keep an eye on temperatures when on the testbench, because cooling is significantly less than in flight. 5500~6000 RPM continuous with an 18 x 6 is about the max (but of course you can run it half a minute WOT, as long as you give it enough time at lower RPM to cool down a bit inbetween).
In flight, it will only run hot under really extreme use, use that this engine was anyway never intended for, as they never were built as aerobatic performance engines.

Rcplanedan

thanks bert.

yeah must say i got lucky..well it doesn't even hesitate from idle to mid or even a quick idle to full throttle..im amazed , i set it a tad rich on idle and 1 click at a time to get it up in rpm for full throttle..but ive only let it idle and a little 3k rpm..and cooling in-between short runs..its like 35 c again today..
it does seem to run a bit rich on the right cylinder..well it should come good..
what would you recommend for a prop on this engine?
Im running a 16x7 at present..i have to search for a aircraft aswell to fit the engine..

1967brutus

The right unit running rich is what mine did as well... If you flip over the carb, it most probably will shift to the other side. I think it is caused by the fact that the throttle barrel moves to the right when reducing throttle, causing a slight offset for the remaining air slit.

Any prop that allows the engine to spin up to about 7500 on the ground (peaked) is OK.
I myself run the APC 18 x 6W, which is a fairly heavy turning prop, and with that it peaks to 7700 on the ground. I tune for 7200~7300 to allow for unloading in flight, In the air it spins up to 8200 easily with that prop and mixture setting.

In all fairness, although I like the particular behaviour of the combo, the prop is not a perfect match, because airspeed drops a bit too much under towing conditions. I probably could do with a 17 x 8W (if that size exists).
16 x 7 is too light, the engine will probably exceed 9K even on gasoline, and that is bad

Rcplanedan

In all fairness, although I like the particular behaviour of the combo, the prop is not a perfect match, because airspeed drops a bit too much under towing conditions. I probably could do with a 17 x 8W (if that size exists).
16 x 7 is too light, the engine will probably exceed 9K even on gasoline,

got that loud and clear 😆
I knew that prop was too light ..onlone i had worth drilling a 12mm hole in its guts..il definitely source a more suitable prop..you knowcwhat its like blowing bucks on a prop that is useless!! well i. Happy with today's accomplishment..il set this brilliant engine aside ready for what? Airframe i may find for it..
time to figure the asp fs91 carb problem, see if i can get it usable

1967brutus

If you can't get the Saito carb working: the original ASP 91 carb also responds pretty good to the Dremel treatment. But it is necessary to place an isolator between head and header, and also between carb and engine body. I personally always "sandwich" the carb between two isolators (longer bolts needed) and wrap the part of the thread that is in the carb in teflon tape, to also eliminate the heat transferred through the bolts. It makes a significant difference. (this also goes for the solenoid-solution by the way),

Funny enough, on the Twin the carb remains cold enough even without isolator.

Cat 1

My Feedback: (1)

THIS JUST IN !!!!
Breaking news from Northern Canada as sources say there have been reports of a sweet sounding T4 rotary valve Webra running on gas!!!

Busy day today but just had to try this - all stock except for the ignition setup - 11x7 Graupner 3 blade - fuel mix a conservative 8:1- stock carb -

Runs awesome except (as expected) the mid range is thick.. but High and low end are very good - 8700 rpm with conservative needle setting - sub 2000 rpm idle. Very smooth and Quiet with a unique sound.

This was a 2 minute setup - just a quick set of the high and low needles - not electronic magic yet. Big smiles as I think this is going to be a sweet "Put-Put" style motor for the right plane.

https://www.youtube.com/watch?v=Gqcx...ature=youtu.be

Raleighcopter

Add a solenoid, air pump, and controller and show us how good it can be.

1967brutus

Brilliant! Congrats!

Very promising!

1967brutus

If those numbers are correct, that should be close to 0,75 hp... Which absolutely is impressive for an older 10 cc 4stroke on gasoline

Rcplanedan

ohh the saito carb runs perfectly on the 91 now ..
but when i tried the 91 stock carb it just wouldn't work..well i think there was some form of blockage and the hs needle takes a couple of turns from closed before it lets any fuel through..so i will now try that again 😉

Rcplanedan

That webra is running pretty sweet ..will be great to see fully tuned.
wish i had some cooler weather to play in ..another hot day for me

1967brutus

I'd say so, yes... because all my engines except for the radial run with the needle between 1/2 and 3/4th turn open from fully closed.

Cat 1

My Feedback: (1)

Dan.. somewhere between you and I there is a perfect spot to be . - The dam thing just keeps moving up and down.


Got a solenoid mounted so we will see how it behaves today...

1967brutus

Extremely curious!

Glowgeek

Is there any doubt? Of course it'll run great on the solenoid.........they all do.

Raleighcopter

Indeed, and I question most people saying they run well without modifying the carb or using some sort of method to control the middle mixture.

Glowgeek

They do run well........At idle and at 60%-100% throttle. If that's where you fly, all good.

I picked up a Saito 120 fathead, the one with that splended air bleed carb that has a midrange adjustment. I'm going to play with it to see if I can widen the throttle range that it runs well with gas.