ST60 Reverse Rotation

[frank williams]

I had to try it and it's not bad at all. 

I had an ST60 with a reverse rotation crank that was stashed away and I had to try it with a pusher prop, just to see how it would work.  I used one of the wide blade APC 12x6 props from Dennis.  I put it into a 20+ year old plane and headed to the field.  The engine ran really nice in a good four cycle without any effort at all.  One of the 5.5 pitches would probably be better though if I were to persue it.

The line tension overhead was much better than I remembered with a regular tractor prop.  Good vertical eights and hourglass, and the best overhead eights I've ever done with an ST60.  (of course I never really been known for my overheads :-) )

Something to consider now that more pusher props are available.  I know Jett has some reverse cranks for 51, 60, and 65's.

[Bill Hummel]

I gotta ask:  where did you find a reverse crank for an ST 60?

[Dennis Adamisin]

YIKES! I only props I sent you were for ELECTRIC use, not IC.  I hope Bob Reeves checks in here, he has had some great results reversing Saito's (Otias's) and he may have a lead on suitable props for the ST-60.

Fox used to offer reverse cranks for the 35, but they discontinued them.

[Lauri Malila]

 Just to let you know, Yuriy can make a pusher version of the DR.60 prop (13,4x5,9"). I've seen the std. ones work nice with a ST.60. I use the 14,2x6" pusher blades to make my 3-blade props but now I'm thinking to try the smaller ones.

 Lauri

[frank williams]

Bill, the engine was a stock ST, it came with that crank, I've had it a number of years, probably back from the early 70's.  ST made at least one of everything .... dykes ring, right rotation, twin rings, etc .

Dennis, I was gonna put a carbon or wood prop on but that was the only pusher 12" dia that I had handy.  Not enough ground clearance for 13".  It worked pretty well too.

Lauri, is the DR 60 the Yatsenko motor?  What lawn mower engine do you run a 14" 3blade on?

     Otias -  I love it.  ........ my son used to get Otitis Media when he was a kid .....

[don Burke]

I think you'll find from APC that using an E prop on an IC engine is a bad idea.  The hubs are not designed to take the cyclic vibration loads and WILL FAIL if used long enough.  You're playing with fire, hope no one is in the blades paths WHEN they come off.

IMO, if enough people insist on doing uninformed things like this, APC will probably be forced to remove the E props from the market due to idiotic liability lawyers.

[Randy Cuberly]

I think you'll find from APC that using an E prop on an IC engine is a bad idea.  The hubs are not designed to take the cyclic vibration loads and WILL FAIL if used long enough.  You're playing with fire, hope no one is in the blades paths WHEN they come off.

IMO, if enough people insist on doing uninformed things like this, APC will probably be forced to remove the E props from the market due to idiotic liability lawyers.

I'd be careful about calling Frank Williams uninformed.  He's been around a long time doing this stuff and probably carefully considered what he was doing.

Randy C.

[proparc]

Frank knows what's up. I for one, am interested in this APC wide blade business,and would like to know more.

[Bob Reeves]

YIKES! I only props I sent you were for ELECTRIC use, not IC.  I hope Bob Reeves checks in here, he has had some great results reversing Saito's (Otias's) and he may have a lead on suitable props for the ST-60.

Fox used to offer reverse cranks for the 35, but they discontinued them.

I've pretty well settled on the JFX 13-6 for both the Saito 56 and 62 running reverse. Wished they made a 13-5 because they are almost too efficient (or effectively pitched a little high). Have to set the 56 in my Latency at 7850 and would like to be closer to 8100.

http://www.himodel.com/plane/JXF_13x6_inch_Beechwood_Propeller_Counter_Rotating.html

JFX makes an electric version that I actually tried but the blades are too thin and the prop blades vibrated badly.

[jose modesto]

Frank. Jose Modesto,thanks for the props they have arrived. Attached a couple of photos of the Yatsenko pusher wood prop.
i have been using them on my Esharks and they work great. Here in NYC we use the tractor prop 13.4x5.9 on our Big Jim ST60 5% nitro with real goos results.
Jose Modesto

[Howard Rush]

You could put it on the back of your airplane.  Then you could use a regular prop.  That wouldn't give you the benefit of the backwards rotation, though.  Alternatively, you could put a Supertigre .60 with a regular crankshaft on the back of your airplane to get the rotation benefit, but then you'd need a backwards prop.

Hope this helps.

[Larry Cunningham]

I was wondering if a backwards rotation ST .60 was as seriously bad vibrator as the conventional ones. How could that not be the case?

I remember these engines having absolutely fantastic stunt runs, in spite of the nose of the ship (e.g., SIG Magnum) shaking into a visible blurr.

But I can only imagine how poorly an electric prop would hold up in that application.

L.

"Teeth extracted by the latest methodists." -Hong Kong dental advertisement

[frank williams]

don,
I only ran the e prop for a few runs.  You are right the cyclic vibration loads of and ic are certianly a factor on prop structural loads.  Best I not tell you of some of the other props I've run.
and
Larry,
yes it shakes just as much as a normal ST, but such a nice sound.  It really ran pretty well right out of the gate.
and ,
Bob,
I've got some reverse cams I'm gonna put in some Saitos sometime soon.
and,
Jose,
I assume the Shark e props are made from a lite weight wood.  Constant pitch or progressive?
and,
Howard,
Thanks for the help

[Darkstar1]

Sometimes what happens at Scobee stays at Scobee! 

[bob whitney]

Frank  i have just done up two APC E wide blade props in cacbon  ,One 12/6 RH and one LH .i am going to try the RH prop on my S/T 60 tomorrow . would love to have a LH crank, Rad Racer .i also have a 13/4.5 LH also in carbon

[Lauri Malila]

Lauri, is the DR 60 the Yatsenko motor?  What lawn mower engine do you run a 14" 3blade on?

     
[/quote]

 Yes, that's what I mean. The props are constant pitch but they can be tweaked easily. Made of maple.
 The big props are for MB .77 engine. L

[dankar]

Interesting post but I like my ST .60's the way they are. Best luck with this.

[Joe Yau]

Frank  i have just done up two APC E wide blade props in cacbon

Hi Bob,

Could you post a pic of your CF version of the APC-E wide blade (12x6.5 WEP)?  thinking of using it on the Otias .56. 

[Dan McEntee]

  I imagine a stock out of the box ST.60 with reverse crank was intended for a Class II (or .60 size) Carrier model? Look in the old mags from back in the day and several guys used reverse cranks and left handed props to help keep lines tight on takeoff, and on low speed laps. I've been wanting to try a left handed engine well before all the electric stuff came about. I would like to do a Sheeks Mosquito with two LA or FP.25's with counter rotating propellers just for giggles and grins. I'm gonna try the reverse Saito deal as soon as I get the time to convert one of my engines.
   Type at you later,
    Dan McEntee

[bob whitney]

send me your E-mail, and i will send you pictures , i just put one on my big job  with a S/T 60 this morning and it really felt good ,plenty of pull

[Chris Wilson]

I had to try it and it's not bad at all.  

I had an ST60 with a reverse rotation crank that was stashed away and I had to try it with a pusher prop, just to see how it would work.  I used one of the wide blade APC 12x6 props from Dennis.  I put it into a 20+ year old plane and headed to the field.  The engine ran really nice in a good four cycle without any effort at all.  

Hi Frank,
             I have heard of reverse rotation engines suffering from a slight lack of power for two reasons.

1. The crank swirl is now going against the porting so that you lose some of the forced charge into the transfer port,
2. The above can give rise to having to run a slightly richer mixture to compensate because charge wants to linger longer down below.

At least point 2 is the experience of a friend of mine who has flown an old horizontally opposed Fox twin that has identical but mirrored cylinders, he had to run the 'reversed' or mirrored cylinder very much richer in order to match both pots whilst running, and strangely the mirrored pot tended to overheat when run at the same setting as the other one.

How is point 1 working for you mate?

[RC Storick]

No to be a smart Ass but do you think better line tension could be because of more concentrated weight in the nose? Seeing as the Nobler was designed for a FOX.35 at 6 oz and the super tiger is 13 oz.

[Bob Reeves]

No to be a smart Ass but do you think better line tension could be because of more concentrated weight in the nose? Seeing as the Nobler was designed for a FOX.35 at 6 oz and the super tiger is 13 oz.

Nope, the increased line tension overhead is real and a direct effect of running a reverse rotating prop. I have flown two different stunt ships with both normal and reverse rotating Saito 62's with no other changes and my findings are the same. This is the reason most electrics are running reverse rotation, it's very easy to do on an electric and well worth the effort on a Saito 4 stroke..

[frank williams]

Chris,
Haven't noticed any ill effects yet, probably not too big a deal for a stunt motor, but you never know.

Sparky,
It not exactly a "stock" Nobler.  Placed 12th at 1991 Nats and 9th at the team trials that year.  Built for an ST60.  Bearcat like wing with swept te and "huge" tail area (Al calls them "horizontal bi-planes").... will turn on a dime.

Dan,
Carrier or Scale .... it was in the red and yellow ST box  (dates it) ... also had carb and really tall headfins.