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Author Topic: O.S. .25 LA-S hints tips experiences?  (Read 2931 times)

Offline jeffindayton

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O.S. .25 LA-S hints tips experiences?
« on: May 10, 2006, 05:41:06 PM »
O.S. .25 LA-S hints, tips, experiences?

Will be using on Scratch built FlightStreak.
 
Thanks StuntHanger!
Jeffindayton
yes OHIO

tmi?
« Last Edit: May 11, 2006, 11:57:17 AM by jeffindayton »
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Offline jeffindayton

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #1 on: May 12, 2006, 02:10:50 PM »
Well, I see Dan's info on the FP20 has informed all...and it is a great work...see the fp20 down loadable 37 page how to guide.....he really tells it all....HOWEVER I just ordered a OS 25 LA-S

I saw that Mr. Pratt (see photos of Primary Force) has changed some things about his OS 25 LA-S...like the needle looks like it came off a Super Tigre....and its not remote mounted....additionally it looks like the fuel hose goes over and then in some where on the engine....this is cool.... wish I knew his setup???

Maybe I should call Harry Roe...

What's this about P40 class.....is this in AMA rule book? %^

I am I living under a rock? ???

maybe this is the Brodak 25???? which I have never seen a photo :'(

Just Jeffindayton....mussing
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Offline Dennis Moritz

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #2 on: May 12, 2006, 05:51:07 PM »
I ran an LA25 for a season and a half on an ARF Flite Streak. Used Powermast %5, %22 (half and half.) Probably an OS no.3 plug. Believe it came with that plug. I used the stock muffler which has the same magic number that Mr. Rutherford recommends for the FP20. Ran about half a tank or less when starting out. Then flew it with no fuss or muss for the entire season. Along the way I put in a stock FP needlevalve through the original venturi. Didn't even bother to remove the old remote needle from the backplate. Flew it like that perhaps 150 trouble free flights. Tank needs to be elevated about an 1/8" above the center of the venturi. Used a chicken hopper and a smith tanks at various times. 9x4 or 9x6 prop. Whatever OS put in that manual. Muffler pressure and no uniflow. Usually set it in a mid level 2 cycle. The kitted Streaks use a more robust construction design. Probably run a little heavier. The LA 25 had plenty left, could have leaned it out anytime for more power. With this engine Streaks are excellent stunt trainers and a low key fun plane. My FP35s and FP40 made for a honking good time. But the LA25 is a cool way to study the simpler stunt moves.Also, had no problem with this set up when the weird winds blew. Would waddle back and forth, shaking it head, and continue on. Excellent forgiving combo.

I wonder about the engine lugging a Primary Force or a Twister for that matter. Although I've read where those of vast experience match the LA25 to that sized plane. My Twister uses a bear of an FP40 to pull it around. Feels good to me. Love the tug. Not too fast either.

Dennis Moritz
« Last Edit: May 12, 2006, 08:33:34 PM by Dennis Moritz »
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Offline Bill Little

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #3 on: May 12, 2006, 09:30:08 PM »
Hi Jeff,

I think I would agree with Dennis that the LA 25 should be a nice combo with the Flite Streak.  I usually hear of a 9-4 to 9-5 APC prop and the fuel Dennis mentions, from which ever manufacturer you get it.  I use Sig or Powermaster, 5%-10% nitro, 20-22% 1/2 and 1/2 Synthetic/castor oil blend.  A 2 cycle run as Dennis describes, not a 4-2.

I would suggest that you set the control horn length on the elevator to give you about 20* movement up/down (40* total), and use the inside hole on the bellcrank.  Use a guide about 1/2 way back on the pushrod to help prevent flexing.  I can't recall the CG, but I *believe* it should be around the spar.  A Streak can get real touchy if there is too much control input and the cg is back too far.  Even to the point of being unflyable for most.  y1

"PaPA" Dave Hemstraught was using a 25LA in a ARF Nobler for Classic last year with much success, so the engine is a good one.
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Offline jeffindayton

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #4 on: May 12, 2006, 10:53:07 PM »
HEY!  Thanks for the input....I just covered fin and stab tonight on FStreak
hoping engine hits the front door via the postal service soon

Fire it up f~

icon fit had to say it.... #^
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Offline Bill Little

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #5 on: May 13, 2006, 09:02:59 AM »
Quote from: jeffindayton on May 12, 2006, 10:53:07 PM
HEY!  Thanks for the input....I just covered fin and stab tonight on FStreak
hoping engine hits the front door via the postal service soon

Fire it up f~

icon fit had to say it.... #^

 **) **) x:

A nice benefit to the small OS (LA/FP) engines with the 2030 stock muffler is that they run a nice 2 cycle and are SO QUIET!  You can actually carry on a normal conversation with your buddies while flying!
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Offline jeffindayton

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #6 on: May 13, 2006, 07:04:57 PM »
So you don't think I should run it rich....

how can I get the laps down to 5 seconds or is this 5 second lap time of any importance?

Thank again,
Jeffindayton ^-^
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Offline Bob Reeves

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #7 on: May 13, 2006, 07:55:19 PM »
The trick is to let the engine run where it's happy and adjust your air speed with prop pitch. Never owned an LA 25 but if I had one I would start with a 9-4, set it so it is running in a rich two stroke and see what happens.

If you get a consistant run but the airplane is flying slow go up to a 9-5, if the engine seems to have plenty of poop but the airplane seems sluggish try more diameter. Many if this.... try that's so you just have to play with props till you find the right combination that makes both the engine and airplane happy.

To large a prop will make the engine lug and overheat so be careful about going too big.
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Offline Brett Buck

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #8 on: May 14, 2006, 08:22:14 PM »
Quote from: jeffindayton on May 13, 2006, 07:04:57 PM
So you don't think I should run it rich....

how can I get the laps down to 5 seconds or is this 5 second lap time of any importance?
 

    It's not of any importance. Just like airplane weights, slow lap times used to be a bragging point. But the important thing is not how fast it's actually flying, it's how   fast it *seems* it's flying. I've flown flights at 5.7 that seemed to be on the verge of getting away from me, and I've flown flights at 4.5 that seemed like slow motion. Naturally, you generally want the "slow motion" feeling.

      The magic of the 20FP/APC 9-4 system is that is has that "slow motion" feeling straight out of the box. I haven't seen quite as much of that with the 25LA, but in any case, you want the engine to be running in a medium 2-stroke, and you can only get 4" pitch props. So it will wind up in the 4.5-4.8 second lap range on reasonable-length lines (58-61').

       Brett
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Offline Bill Little

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #9 on: May 15, 2006, 06:46:20 AM »
Like Brett says!  y1

When I started flying my Tomahawk w/BBTU FP 20, I didn't use a tach or stop watch.  I just flew three flights which is what it took to get the needle set to where the plane was happy.  !st, too rich; 2nd, too lean; 3rd, just right.  THEN I tached it and never did put a stop watch on it.  It was at about 4.8 on 60' lines center to center,  but felt like 5.5!

If my son hadn't timed it, I wouldn't have believed it.  <=

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Big Bear <><

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Offline Brett Buck

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #10 on: May 16, 2006, 05:09:19 PM »
Quote from: Bill Little on May 15, 2006, 06:46:20 AM
  THEN I tached it and never did put a stop watch on it.  It was at about 4.8 on 60' lines center to center,  but felt like 5.5!

If my son hadn't timed it, I wouldn't have believed it.  <=


   You can get that with TP motors, too, and the 40VF does that quite easily. The other engines can take some work to get that feeling, which is why you sometimes see some unusual set ups for me and my buddies.

   Brett
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Offline Bill Little

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #11 on: May 16, 2006, 10:22:46 PM »
Quote from: Brett Buck on May 16, 2006, 05:09:19 PM
   You can get that with TP motors, too, and the 40VF does that quite easily. The other engines can take some work to get that feeling, which is why you sometimes see some unusual set ups for me and my buddies.

   Brett

I always enjoyed my 40VF planes on pipe.  I even got Paul's "outdated, too small prop" set up from him.  ;D

This year will see an Imitation (foam wings from a zillion years ago!) with my 40VF on a pipe.  %^
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Offline RandySmith

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Re: O.S. .25 LA-S hints tips experiences?
« Reply #12 on: May 16, 2006, 10:50:31 PM »
Everyone at stunt camp last weekend  had  that  slow motion  manouver  speed. It was a joy to watch, same speed ,up down, sideways , LOL

Bill Rich brought his  brand New  SV-22 EXEL  with a PA 65 in it. Very clean everywhere  and  very easy to fly well.
he may  do  very well at the NATs  this  year

Randy
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