LA46 fuel economy

LAST EDITED ON Sep-20-02 AT 04:44 PM (CDT)

We had an interesting discovery yesterday. Fred and I were helping a fellow club member with his Brodak Cardinal. He was powering it with a stock FP40 which had ~4 head gaskets. It was pretty anemic on the plane, which wasn't particularly light.

I suggested he try my stock LA46, an engine I had purchased used (=rc abused!) for $15. I was interested in how well it would run in a plane, but I don't have any planes this large.

So yesterday he showed up with my LA46 on the Cardinal and a 4 oz plastic clunk tank (setup as a uniflow, with the uniflow tube simply plumbed to the outside edge of the tank). He also was using a tongue muffler, and a cutdown Graupner 12-5 (to 11 inch). He had installed a stock fp40 venturi with an OS spraybar.

Well, the engine really did perform well. It grunted around in a strong 4 stroke. However he was only getting a little over 4 minutes on the 4 oz tank. We tried other props (APC 12.25x3.75), fuel (10% and 5 % nitro Sig Champion), tried to lean out a bit, but still the time was only a little over 4 minutes. Still the engine run was pretty impressive, but we felt like we were being teased by the short run.

Anyway to shorten this treatise a bit, he returned last evening after replacing the OS spraybar by a ST spraybar, and swapping out the tongue muffler with the stock OS CL muffler for the FP. Tank was left alone (still 4 oz).

Well he can now get ~8 minute flights, and the engine is still performing well (he plans to increase the line length (now 60 ft) to get the lap time into the 5.3 secon range).

So we were pretty surprised to see such a large change in fuel economy. We are guessing the biggest effect is that the stock muffler is more restrictive, but we didn't have time to swap the tongue muffler back on to see what would happen.

I promised not to say "Who" we we helping, but he should be at the St. Louis Contest this Sunday.

The ST NV is probably restricting the flow somewhat and giving you a longer run. I generally put a .35 venturi on my .46s (and some people will tell you the .46 and .35 venturi are the same, but when I measure them, they aren't), which is the middle size of the three available OS venturis 2 years ago when I needed them. Anyway, the muffler might also have an effect, but you can plug holes on the tongue and also restrict flow. I love lightweight tongues and I like to fly O.S.s, but my two .46 LAs are kinda the ugly stepchild in the "looks" department. Reliable as Heck, though. And pull like a tractor. Best $65 engine I've seen since I got back into this.

LAST EDITED ON Sep-20-02 AT 08:38 PM (CDT)

Alan,

I've been running an R/C LA 46 that I bought at a swap meet last January. I put in a small OS Venturi and a Double Star NVA. Later I added a Mac's One Piece Muffler (#6650).

With a 12-5 Zinger wood prop it runs like it is on rails. Absolutely no variation in rpm from launch to cut-off. I launch at 8200 rpm, and I can put no more than 3-1/4 oz and still get down in under 8 minutes. If I launch at 8400 rpm I can run as much as 9+ minutes on the same fuel.

The plane is not heavy (about 46 oz when new two years ago), and the 46 would probably be considered too much engine under normal circumstances. But, the Mac's muffler has a two-fold effect. First, to stealy power, but, most importantly, it gives a almost perfect run.

Just my 2 cents,

Bill Francis

Oh yes, I'm flying on 65 ft. lines.

>Well he can now get ~8
>minute flights, and the engine
>is still performing well (he
>plans to increase the line
>length (now 60 ft) to
>get the lap time into
>the 5.3 secon range).

Alan;

Just curious as to how much run time was on the engine - even though you say it was "RC Abused." I've picked up engines from RC flyers that were literally flown once - then cracked up, carb broken, and sold off for a good price.

My experience with OS ABC/ABN engines has been that they are real fuel hogs when you first start running them, but after 30-45 minutes or so of run time settle out and the result is much better fuel economy.

I'm running mine dead stock (no extra shims)on a 3-blade 10-7 prop. Using the standard OS NV. I get more than enought time to complete the pattern on 3 3/4 oz. of fuel. Most reliably starting and running engine I own.

I'm guessing mine was like yours; it had obviously been crashed, but the insides looked clean. I stripped the blue paint off because some had been scraped off during the crash.

My guess is that some beginner bought it with an arf. When he took it to the rc field, he was probably also abused since the FP's and LA's get no respect. When it crashed, he was probably happy to have an excuse to get rid of it, and get a "real" engine---you know, the ones with ball...bearings that is.

Their loss, my gain.

<>

Alan, how did you strip off the blue paint finish??

Steve

Well, I just dropped it into a jar of nasty paint remover--the good stuff with methylene chloride. The key is to make sure that the entire engine is beneath the paint remover level. I had one lug which was poking up and not completely covered and it turned out to be slightly discolored. The rest looked just fine. I just let it sit for 24 hours. Then scrubb with water and a stiff bristle brush.

I have heard that the crock pot treatment with prestone also removes the paint, but someone else might comment if that does work.

Gives you confidence, doesn't it, that they only charge five dollars extra for the paint which you can (and probably want to) remove with paint remover.

My LA 46 needs 4.5 oz for pattern plus maybe 5-12 laps on 55 oz, 610 inch airplane. OS stock venturi, ST NVA, no extra shims 7.5% 22% fuel, APC 11.5-4, tongue muffler.
Strong,gutsy, gurgleing 2 cycle, tons of power on heavy airplane, consistent and reliable.

4.5 oz. uniflow, 7800-8000 rpm, 11x6 prop, extra gasket, ST needle, stk. venturi, 10% nitro, 22% oil, 64x.018, 5.2-5.3 lap times, slightly heavy Brodak Cardinal, 2-4-2 as good as it gets!

Mark Boesen

Mark B.: Stock muffler? I am perplexed by Bill Francis' launch rpm with the Mac's #6650. I've been running this muffler on the .46LA all summer. The best prop is as Scott Riese predicted, an 11.5 x 4 APC, tho I have tried cutting down the 12.25 x 3.75 as much as 11". In any case, the launch rpm has to be 10k to 10.2k. The thing that puzzles me is that I got a Big Art tube muffler from Leonard, to approximate Doug Moon's setup. The 12.25 x 3.75 would not go nearly fast enough for my OTS, which is not a big surprise. I found a 12-5 APC worked fairly well, as did an 11-6EW Rev-Up. The surprise was that I still had to launch at 10k with the 12-5, and the airplane is slower. Run time is down from the run time with the Mac's, by at least a minute or more, close to 4 minutes on 4 oz. Going to install the .40LA and Mac's #6650 ASAP. Steve

LAST EDITED ON Sep-22-02 AT 08:15 PM (CDT)

I can't explain the run times. But, I have used both of the APC props you mentioned. I have found that they don't "load up" (if that is the right term) nearly as much as the Zinger. I ran the APC's with a Big Art Tongue muffler on the LA 46 and had to launch a much higher RPM ... appx. 9600, but not 10k. Also the power was much reduced. The same setup with a Zinger 12-5 results in a much more "apparent" power. I believe the launch RPM was closer to 9k to 9200 with the Zinger.

I haven't found the "flat blade" APC's to fit into any C/L nitch. However, I do run them on an OS 40 SF on a Sig Fazer (R/C). I don't know what the full throttle RPM is, but it must be 12k+.

I have found the APC 11-5 to be a pretty good match for an FP 40, launched in the high 8600 to 8800 rpm range with a tongue muffler.

I can't explain the fuel economy with the LA 46 and the MAC's 6650, but it is there and VERY repeatable.

Hi Steve, I'm running a Big Art Muffler, looks just like the old Super Tiger muffler, Hmmm... I also tried a Rev up 12x5 but lost all speed, and nice clean 2-4 break, the engine seems very happy with a reworked 12x6 Power Prop cut down to 11x6.

>to approximate Doug Moon's setup.
>The 12.25 x 3.75 would
>not go nearly fast enough
>for my OTS, which is
>not a big surprise.

I launch at 10000. I use the APC mentioned above. 5% nitro sig 4 oz gives me 7 minutes. 10% and I only get about 6:30 on 4 oz. It wouldnt go fast enough? That makes me curious.

>Gives you confidence, doesn't it, that
>they only charge five dollars
>extra for the paint which
>you can (and probably want
>to) remove with paint remover.
>
>
>Leonard Neumann

Why would you want to remove the Blue paint. My la 25 matches my P-Force. It looks cool.

>DMoon

>
>Why would you want to remove
>the Blue paint. My
>la 25 matches my P-Force.
> It looks cool.
>
>DMoon

Well, Allen Did because it got scratched up. I don't think it enhances cooling, and if the engine gets gunked up, it is awfully hard to clean without removing paint.

However, if you don't have problems with it and it matches your paint scheme, then you obviously want to keep it.

I flew with "him" Sunday in Intermediate. He was worried about crashing and breaking the borrowed engine. I told him if a "friend" loaned it to him, don't worry if he broke it, the "friend" would understand. That did not take away his worries, but he did fly well and stayed up for at least 7 plus minutes. I crashed and will NEVER use a Fox again, not even in OTS. I shall stick with my trusty, fuel economical OS Max .35 and 40 FP engines.

Well I'm glad that "he Who won't be named" was a little worried about my $15 engine. After seeing how his superb Tigre 46 was splatted across the asphalt at the Milwaukee Father's day contest, I was just a little apprehensive!

But basically if I'm willing to loan it, I'm willing to accept the consequences--besides I have another NIB LA46.

Reporting on "Who"

We aren't sure "Who" borrowed your 46. Are you sure it was
locked up good? "Who" do we know that has hundreds of engines
and surely must have many 46's? Bill Calkins pitted for a
L.A. 46 which finished 2nd in its class. Despite some early
problems with "what comes next" "Who" flew as well as we've
seen him. Be careful if "Who" returns you some poppit valve
stuff.

Russ Gifford