Any thoughts on , If I put a 13 x 4 APC on & a .315 intake . Straight fuel ( 18 % Oil )

Hold the nose straight up , set it 2 or 3 clicks out from lean , and let er rip .

( Trying to get full nasty weather control autority via slipstream prop flow over flaps/ stab. Rather than waffling along and dragged around the sky by twisters hurricanes & suchlike . )

Some people , who shall remain nameless , are of the opinion itll sieze up , or perhaps snap the crank .

Pickhard ran a STalker 46 hard out on a 9x4 for a few hours or gallons to see if it'd hack it . Maybe this'll hold . ?

Abrasive observations & comments if pertinant wecolmed . 

   I think most guys run Stalkers with more pitch. I think it would work ok but as not to waste a day at the field I'd bring a couple other props with me just in case .
  John L.

I got my first Stalker, a .61, around the turn of the century. I now own and operate about a dozen of them, sized from .40 - .81. I do not run Castor Oil in any of them, nor do I run Nitro. Their design and metallurgy is such that FAI/17%Syn. fuel is just fine. They seem to prefer running more pitch, lower RPM, in the torque curve, I believe, and that's how I run mine.

Stalkers are not "Schneurlly" engines. IMNSO,  they represent the peak of the old "Cross Flow", pre-Schnuerlly, engine designs. Perhaps the last, and arguably the best from that time, would be the Super Tiger .60, though the Stalker may run better, and without the shaking of that great classic Stunt engine.

Needle and run it similar to the Super Tiger. It's a good starting point.  At the beginning, consider using a proper length prop, with 6-8" pitch, and launch at 6-9K depending on the prop and pitch. The engine will let you know when it's happy, after its broken in.

When it's broken in, the fuel usage will stabilize. you'll notice it. you may be surprised at the low fuel usage.

You can run it with a flatter prop, at higher RPM, and it will take it, You can also tip the Nitro, but it's not going to be as good as a schnuerlly on a pipe or  header muffler. You might be happier going with a pipe engine in the first place.

Despite being designed to use synthetic oil in the fuel mix, if you just feel the need to add Castor, don't  go over 5%. The Stalker, like many other engines may "Coke" up, and require a de-coking after a period of time running more than this.  Running 5% castor with 12% good synthetic oil, the syn. should be able to keep the engine internals clean. 17 - 18% total oil, mostly, or all syn. should be fine. I've run mine on 17% all synthetic for all these years, and they have been fine.

Many in the past 20 years, have spent a lot of time, money, and frustration, trying to make Stalkers run like a modern pipe engine. They don't succeed at that most of the time. Ive seen examples where so much has been done trying to get to somewhere closer to a real pipe run that it was the ruination of a fine stunt engine.

I believe that if you cannot get the run, or the power you desire from, let's say, a Stalker 40, then go back to how it was designed to run. FAI fuel, and 6-7 pitch prop. Still want, or need more, step up to the next larger size, or, rather than try to make one run like a pipe engine, buy the engine and the pipe.

If you like the sound of a stunt engine running in a growler 4 stroke, switching to a 2 cycle when needed, a classic stunt run, that's where the Stalkers shine. Ball bearings, better balanced, and good power, IMO, is available, stock, with FAI fuel. There's plenty of power, size for size, and of course rear exhaust is the normal, though side exhaust is available.

John Miller

Just don't do it. Sheer idiocy on the .76

We ran early .61's on pipe at 10,000rpm and 20% nitro on 12 x 3.25 - 3 blade - but they are much happier to spin than the 76.

What are you going to fly it in, Matt?

Ive got it in the Five Ton Folkerts ,well 80 Oz Actually . But the loadings only about 15 per Sq Ft.

This sucker along with the 80 Oz Strega , has me thinking six foot 20 stone pilots  arnt what they used o be , and I may just have slightly overdone it .
Is a 57 incher scaled to 63 inch span . ( 1/7 th .  were told that that is 0.14285714285  BUT knacturely its that times that , wots really 1.30612244896 Area .)
VOLUME / - Displacement ( Amount of atmosphere it takes up- or displaces ) is MORE AGAIN .
So I shoulda gone to 60 inch . Or the gym & hamburger joint .

The P.M. 60 is good with a SF 46 OS on 15 % Nitro & a 12 x 6 . bit marginal on 6 Oz Fuel .


However , Thinking is if the 76 is at the ' Valve Float ' or ' lifter pump up ' limit , and the rests sound , It'd sit ' up there ' and under load increase tourque due to increased intake depresion ( suck = more juice ) .

Thats if there isnt an almighty bang .

Go to 4:30 . 

Id think a OS FSR 50 wouldve been maybe the right thing , wanting to run the nominal 4 inch pitch . The smaller ones HP 40 PRP rear intake was magnificent in wind - around 20 mph or better .
Thus, logic tells us  , A OS 45 SR rear intake , with the Std. liner , Shoud be the goods . But not bigenough . Will have to check on OS 50 rear intake schneurles .Al the 60 R I 's are 18 ounce or more,
or the Webra/HP sounds good . If the pilot was a appropriate size.

As I said , maybe a wentt a step past what I thought was Max Size to hold onto in a gale . for a 11 stone bloke, anyway .

The problems finding the controlled power to match a gale , to turn the prop . And a 60 mph plane ( 5.0 per lap on 70s ) Thereabouts. Will go backward in a 60 knot gust . Unless somethings done about it .
The Little Folkerts the needle was 1/4 turn , cowl on- cowl off , for the same rpm .rear induction. So wonder if the ' sealed engine bay - as it were , had some Force Feed effect, where the power came on with
extra intake pressure . As per a Plenum chamber . It would seem it would have to .

Finally,
As the Stalker 76 is in and fits ( a side Ex pumped oil all about - requireing remedies. ) If it'd hold together sorely abused , it may just work. Well. on a 4 in pitch . A bit tractor like on the 14 X 6 .
but thats the best for drive and least Tourgue ( or whatever - Gyro ) on slammed hard Square Corners .

Ive set it up to take the 46 OS etc & the S Tigre 60 , now. as well as the Stalker 66/76 . 66 wont hack that weight. to big an intake and it sags/ dries off , on hard corners .

Incidently , seen the Gold Head 61s here go well on 15 % Nitro . Brian Eather said he used 20 % in these two ( 66 /76 ) but Ive found they behave on no nitro , and dont like the stuff .Tend to lean off )

The HP 40 , being a rear induction pylon race motor , was safe to 20.000 PLUS. easy .
It would chunter round , with a seeming even airspeed , the revs fluctuateing ( Like a impulse tachometer ! even . ) to match any wind gust to be found  . Hence a prediliction to emulate this. But Bigger .

  Like I  say ,  the reason my crank broke is I was careless , a new , tight , high compression engine that I couldn't turn over so I used an electric starter.
          John L.

This is the sucker its in, for now . 63 Span, 820 sq in . 82 ounce . Likely itll be put in a less voluminous Hawker Hurricane, when thats finally got done .