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Author Topic: reworking LA46  (Read 1791 times)

Offline Jim Morris

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reworking LA46
« on: July 15, 2011, 06:50:31 AM »
Hi guys, after a long lay off(actually just flat out quit ) after running my two best ships into the ground within a week just before a contest, but anyway, Im seriously thinking of going at it again (miss it) .So all I have left over is an LA46 and a NIB Stalker 61RE. I want to start with a modified Twister or Banshee for the 46,but was wondering if anyone could rework it for a nice 2-4-2. Im sorry if this has been covered before, and I am aware that people get that with their set ups,but I would rather cut to the chase if I can send it off to have it done. Thanks.

Offline Andrew Tinsley

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Re: reworking LA46
« Reply #1 on: July 15, 2011, 07:00:33 AM »
Hello Jim,
  I would leave well alone and just use the LA46 as is. It is an excellent engine straight out of the box and reworking is liable to leave you wth an engine that is down on power. I run my LA46s with the standard large OS Venturi (FP 40 type) and standard OS NVA. I run mine in a wet twostroke, but others use the smaller FP 20, LA 25 venturi and get good results. I am about to try this. Take a look at the pinned topic near the head of the index, that shows you what people use. I understand that a 4-2-4 style run can be had, but I have never gone this route.
  Think twice before any major mods, just play around with fuel, props, venturis and NVAs. One of my LA 46s needed an extra head gasket, but apart from all this, just run them stock.

Regards,

Andrew.
BMFA Number 64862

Offline Steve Helmick

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Re: reworking LA46
« Reply #2 on: July 15, 2011, 10:36:25 AM »
I'm with Andrew (but use a PA NV assy.). My next .46LA powered plane will be a stock .46 with a tuned pipe...a modified kit Pathfinder.

If you really gotta get your .46 reworked, call up Randy Smith.   y1 Steve
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Offline Andrew Tinsley

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Re: reworking LA46
« Reply #3 on: July 15, 2011, 10:50:18 AM »
Hello Jim,
  I agree with Steve, the PA NVA is about as good as you can get. It is a little bit more expensive than an OS assembly, but ease of adjustment and quality (no leaks) is outstanding. I am just a cheapskate and my flying abilities are .......well let us just say not the best, so I tend to use a cheaper fix!

Regards,

Andrew.
BMFA Number 64862

Offline Mark Scarborough

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Re: reworking LA46
« Reply #4 on: July 15, 2011, 11:37:14 AM »
On the LA 46, trying to get a Fox 35 style run is not really beneficial, nor is it desirable IMHO.
The LA 46 runs great right out of the box. Its light, reliable, reasonable on fuel and inexpensive. Just what you want when there is a chance you will find the ground in an unfriendly angle...

Latest news on setup,, take it out of the box, put a .272, - .275 venturi on it, with a ST or PA needle assemble THROUGH the venturi, in other words, dont use the remote needle ( this isnt a deal breaker, but if you dont use a through the venturi needle of the same size as the ST or PA needle, then you need to recalculate the venturi size) Use an APC 12.25 x 3.75 prop, 10% nitro fuel with 22 % oil, equal parts castor and synth. I would reccomend a 5 oz Uniflow tank with muffler pressure, ( it makes certain things more consistant) Needle it for 9600 to 9800 depending upon your airframe and tank setup. release it and enjoy.
Break in would be several tanks on the ground, but you will find the run " sweetens up" as it gets closer to a gallon of fuel through it
I have not ever needed to add shims, remove shims, alter ports or timing.
the only thing I noted was that one of mine needed a bit more castor to be happy. IOW it would pick up rpm noticable when I flew the square eights, and then stay at that rpm instead of coming back down. a couple ounces more castor added to the gal of fuel solved that problem.
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Offline Chris Wilson

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Re: reworking LA46
« Reply #5 on: July 17, 2011, 11:30:56 PM »
Hi guys, after a long lay off(actually just flat out quit ) after running my two best ships into the ground within a week just before a contest, but anyway, Im seriously thinking of going at it again (miss it) .So all I have left over is an LA46 and a NIB Stalker 61RE. I want to start with a modified Twister or Banshee for the 46,but was wondering if anyone could rework it for a nice 2-4-2. Im sorry if this has been covered before, and I am aware that people get that with their set ups,but I would rather cut to the chase if I can send it off to have it done. Thanks.

I read an article in the Australian Control Line News on the LA 46 and it stated that you 'could' adjust the transfer timing by very slightly filing the piston crown to achieve a better break.

Off to find said article right now!

P.S. This link trashes the above idea soundly though!  http://stunthanger.com/smf/index.php?topic=16924.0;prev_next=next
MAAA AUS 73427

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Offline Andrew Tinsley

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Re: reworking LA46
« Reply #6 on: July 18, 2011, 07:04:06 AM »
Hello Chris,
  The article you want is called Bluer than Blue and is by Derek Piccard (Sp?). It appeared in AMI magazine and was first published in Vic Stunt. He recommends that the tops of the inlet port are filed by a few thou to angle upwards. He gives an alternative of filing slots in the piston, which align with the inlet port. All this is to get a better 4-2-4 break.
  I suppose if you must have a 4-2-4 set up, then it is worth doing this. BUT the engine runs like a sewing machine in a constant 2 stroke. This gives a super performance, much better than a 4-2-4. Why anyone would want to do this is beyond me. Please try the engine unmodified, you will really like the constant 2 stroke run. I run mine in a wet two and that works for me.

Regards,

Andrew.
BMFA Number 64862

Offline Greg L Bahrman

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Re: reworking LA46
« Reply #7 on: July 18, 2011, 09:07:36 PM »
HI Chris,
I read the article and followed the advise for modification of the LA46. Mine runs really good, a solid 4 stroke and a little break to the top of manuvers so I am very happy. The other side of the coin is that there are many LA46's at the field I fly at that are stock motors and they run every bit as good as mine. I wouldn't say it was a waste of time, but I feel it just really wasn't necessary. OH and I should mention that my modified unit uses more fuel than the stock ones I've seen. I use the popular apc 12 3/4 x 3 3/4 prop. It may have softened the power a little so I got it back by using a larger venturi than most. Launch is 9600 to 9800. Mine works great but the stock ones are just as good. I just can't say mine is better so I will not do it again. Plane was a 50 oz. profile cardinal.......Grins
« Last Edit: July 18, 2011, 10:25:46 PM by Greg L Bahrman »
Greg Bahrman, AMA 312522
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Offline Chris Wilson

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Re: reworking LA46
« Reply #8 on: July 18, 2011, 10:54:32 PM »
The article is in ALCN 70 4 and is indeed called 'Bluer than Blue' by Derek Pickard.

Interesting to note that two shims were used in that modified engine to give an 8.5:1 compression ratio (down from 10.2:1) along with an air filter, 10% nitro fuel (up from 5%) and a 11.5X5 Bolly prop.
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 Nothing in life is so exhilarating as to be shot at without result.  It's not enough that we do our best; sometimes we have to do what's required

Offline Geoff Goodworth

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Re: reworking LA46
« Reply #9 on: July 19, 2011, 03:23:11 PM »
Chris, ACLN 70 4? Can you give us the month and year or issue number, please?

Offline Chris Wilson

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Re: reworking LA46
« Reply #10 on: July 19, 2011, 04:16:29 PM »
Chris, ACLN 70 4? Can you give us the month and year or issue number, please?

Issue September 2003 - from http://www.vicstunt.com/

Go to 'newsletters' top left then ACLN on the right, scroll down to September 2003 and click that and a pdf file should down load for you but will need Acrobat reader to view it.
(Dang good source of info on this site!)

Just Googled 'ACLN 70 4' and it was instantly useless as a search code, sorry about that!
MAAA AUS 73427

You have enemies? Good. That means you've stood up for something, sometime in your life.
 Nothing in life is so exhilarating as to be shot at without result.  It's not enough that we do our best; sometimes we have to do what's required

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