PigMan Buggerus

My Feedback: (6)

After some pretty extreme modifications, and also running 30% nitro, I was able to squeeze 16,500 RPM's out of the yellowjacket. I removed the carb barrel and bored it out as well. Nothing like trying to drill through hardened steel. If you try this, make sure you are dumping oil onto the bit and barrel as you drill, it tends to get rather hot. Anyway after all of this, I was still only able to get 16,500. Also, the rules for SSC prohibit the use of a modified engine, it has to be stock. A guy at the field fired up a brand new OS LA .15 and was turning 16,500 on the first tank. So I guess the moral to this story is to not buy an AP engine, spend the extra $5 get an OS and be happy.

Oh master airscrew is now making a blue colored 8x3 prop that is specially made for SSC combat. My LHS Starfleet Hobbies has them. The prop seems to be stiffer than the normal black MA's. Should be more efficient, and the judges auotomatically know that you are running an 8x3, because it's the only blue prop MA is making.

RogerWilson

Did you bore it out as big as the hole in the carb body so that at open throttle it is completely filled with precious air/fuel mixture? You can do this and also back the needle valve compnent out a few turns to clear it from the middle of the venturi. This will give a little bit better top end as it restricts air flow a shade, but low end stinks when you do this because the fuel slides down the side of the ventury instead of mixing with air and turning to vapor. The guys at my field were raising cane about my measly extra 500 rpm over their peuny magnums and LA's so I've decided to buy a magnum so I won't get any more lip about it. If only AP would cut a bigger throttle barrel hole for their .15 then it would be a legal engine and would be my engine of choice. Then my measly competition would quit belly aching and get em too.

LaneO

Guys, The rules do say no mods to the engine. In my opinion, why buy a engine you have to work on to get it to turn up like the O.S. 15 or the Magumn .15, I have both of these engines and haven't had to do a thing to them.

Is't the cost of the yellowjacket about the same as the O.S. or Mag. anyway.

Lane

PigMan Buggerus

My Feedback: (6)

Lane,

You are correct sir. That is what I said. The OS LA is only $5 more than the AP. I was just mad that the engine didn't perform the way I expected it to. I went the extra mile just to see if it would perform a little better(not really caring at that point whether I tore it up or not). It will perform better, AP really needs to address these design issues that are restricting this engine. If they would only increase the size of the intake and the exhaust, it would be a screaming engine(Love the ball bearings).

Roger,
No I didn't drill out the carb barrel that big. It was a real pain in the butt to drill it as far as I did. I didn't feel like doing it again, especially when I was told I wouldn't be able to use it for SSC anyway. Oh well live and learn, LA or Magnum for me.

CaptainHowdy

Look into the Norvel .15. It's the lightest of all, I believe, and it screams bloody murder, pulls my HOR around better than my OS .20. The only drawback is the silly clip on muffler.

RogerWilson

I agree, I have one on my 1/12th scale pylon racer (progressive miniature aviation ME 109) and it's one of the fastest planes at our field. I used RTV on the muffler to help deter the nasty blow by that happens between muffler and crankcase. It's at www.nearc.rcclubs.com on the 1/12 scale pages.

PigMan Buggerus

My Feedback: (6)

There are 2 different Norvel's in the .15 class. 1 of them is too expensive to use for SSC, the other performs about the same as magnum and OS, no matter what the engine, you aren't allowed to turn over 17,500 RPMs in SSC. Actually, I got quite a bit of flying in this weekend with the OS LA at the helm. After a couple of tanks, I checked the RPMs and found I was running over 17,500. I was running somewhere around 15% nitro. I had to go out and buy a gallon of 5% nitro to bring the speed down a little.

This engine should be perfect.

RogerWilson

I've got a magnum on the way and the only reason I went with it was because of the longevity of the bearings versus the bushings. I know it will probably not matter but I've heard of bushed motors needing bushing replacements after several years of use because of the friction. The bearing roll rather than slide and it seems to me that they would last longer. A combat engine will probably not last that long anyway. I like how the LA has the remote needle valve though. We have half magnums and half LA's with one ASP and my AP flying at our field and they all are pretty even in performance.

boogerboy

My Feedback: (3)

Is that 30.00 shipped? Parcel post is fine with me! I'll take it! Do U take paypal? Cold checks? Dollar now and the rest never? Just kiddin! I'll take it! Let me know how to pay ya! Boogerboy!

PigMan Buggerus

My Feedback: (6)

Booger,
After doing all the mods to this engine, I think I am going to have to keep it. It does perform OK now, so i am probably going to look for a plane for it. Thanks for the offer anyway.

spyder0069

I had great success with my AP 15. I had a global focke wulf with a LA .10 that was horrible. It was mounted inverted and hydrolocked way to easily. Couldn't hand launch the plane and it could barely swing a 7x4 prop. After 12 tanks the LA was getting better but I lost my patience with the engine so I sold it on ebay and bought the yellowjacket. The AP 15 was almost a half ounce lighter than the LA .10. You could immediately see the power difference. Typical prop was a 8x4. An 8x5 seemed a little draggy until about the 5th tank. I ran this combo for many months with awesome success. Easy starts, great performance. Then I found out these have a head shim. After reading many threads I pulled the head shim on it. CRAP a whole different engine. I was just running 15% fuel and this engine felt like it gained an extra 20% performance. I couldn't believe the difference. I eventually sold the plane and then later sold the engine to a friend. I have tried to buy the engine back from him several times but he won't let it go. So I just bought another. I don't even have a plane for it yet but I liked the engine so much I figured I'd have one for when I do find a plane. I had tried the drilling of the carb before and I didn't see much of a difference. I did go one size bigger on the exhaust. The most difference was made with the removal of the head shim and enough flights to let the engine break in.

PigMan Buggerus

My Feedback: (6)

What were you taching with an 8x3? Even after the engine modifications, I could never get the AP to tach above 16,000. My OS LA 15 will swing an 8x3 well over 17,000, and that is withou removing the muffler baffle, which I understand should give even more power. My AP was a dog, of course I never removed a head shim, I didn;t know there was one. Also another member of the club went with the AP .15, and he didn't have any luck either.

spyder0069

Unfortunately at the time I didn't have a tach. Never ran a 8x3 (hobby shop never stocked them). I did also run a 7x4 on it and it would screeeeeeem. I would bet the 7x4 tached at 20k or better. I purchased this second AP .15 used so hopefully it has been taken care of and I'll try taching it. I would be worried about engine life running a LA over 15k. Those are bushed engines and I would be worried about premature wear. The AP has dual ball bearings and can withstand the higher revs. I'll tach this one and find out the rpms. Should get it in the next week.

PigMan Buggerus

My Feedback: (6)

Believe me if the AP had performed, I would have stuck with it. In SSC Combat to be competitive, you really need an engine that will put out close to the max 17,500. The AP just didn't give me enough power.

Allan

FlyingGreg

My Feedback: (4)

Allan: I didn't read every post on this thread, which I was suprised to see is still around, but the SSC rules have been modified to allow linkage adjustments to keep the enginer below the 17.5 rpm limit--as long as any adustments either mechanical or by the radio i.e.shortening the throttle travel, can't be over ridden by flipping a radio switch. Should make buying fuels with different nitro content unneccesary.

See you at the field.

FlyngGreg

PigMan Buggerus

My Feedback: (6)

Awsome! I guess I will be removing that baffle then, and mechanically adjust the engine down. I would think that the LA will turn over 17500 with no baffle.

spyder0069

Well I got my used AP 15 in. It seems to run well. I pulled all the tricks. Enlarged the exhaust, pulled the headshim, bored the carb the next size up. With 15% fuel it ran 16.3k on a 8x4 master airscrew prop. I put a 7x4 on it and got 16.8k. Its 24 degrees here so I don't know if that adds to the equation. This is mounted to a 2x4 woodstand so there is air resistance on both sides that you wouldn't have if it was mounted on a plane. The engine was screamin. Instant throttle response, and I can drop the idle all the way down and it just purrs so slowly you got see to believe. I didn't get a tach of the idle because my hands were numb from sitting behind the prop! But it was incredible. If your getting overr 17k with a LA that is amazing. I would figure the numbers for my 7x4 should be similiar to a 8x3. I'll still take my AP over the LA. Lighter weight, runs good inverted, and its not blue.

gunfighter

My Feedback: (1)

The OS LA will DEFINATELY turn more RPM than even the modified AP. Several piots have tried the mods and still can't get the rpm of the LA even if the mod's were legal in SSC.
As to the bushings - I have been running the LA in combat flying almost every week (I live in Texas so we fly all year) and the original engines are still running strong! No apparent wear in the bushing, although the heads do get discollored after running in the texas heat.
I now have 6 LA's and every one will turn over 17,500 on 10% in the winter (under 40) and will reach or exceed 17,500 in the Texas summer (over 100) on 15 or 20%. I have several LA's which will exceed 18,500.Last spring, I had one engine I could not get below 17,500 even on 5% which was the lowest nitro I had available. The new rule allowing adjustment of the carb barrell allows me to run this engine in competition. The only mods to these engines are removal of the muffler baffle and replacement of the "soft" muffler screws with hard hex head screws.
I have used one of my LA's in open "B" and turned 17,800 with an 8x4 on 25%.
The above figures are static - as I run a bladder tank, the engines unload much higher in the air!

PigMan Buggerus

My Feedback: (6)

That's the reason I got rid of my AP. Stock it's performance was sub-par, modifications to make it competitive also make it illegal for SSC. Plus the drop in OS LA .15, with no modifications, not even removing the baffle in the exhaust(Which is legal), is a great performer, and competitive, right out of the box. I have only had experience with one other LA, a 40 that came on a trainer. It ran OK, but not much power. I think the LA .15 is definately the best of the LA bunch, at least the best of the ones that I have seen.

Cajun

The LA series of engines is not particularly impressive, and the 40 is very unimpressivbe. BUT, the .15 is a hot performing little gem for SSC combat. Just make sure and seal all of the screws and back plate with silicone.

I'm trying a pair of LA.10s for a twin SSC P-38. Hope they are as hot as the .15s

Cajun[8D]

spyder0069

My .10 LA was a dog. My .40 LA rocks! I have owned brand new O.S. .40 FP engines and my .40 LA is every bit as good. BUT......thats because its on a .25 size plane. The .40 is a ounce heavier than a ball bearing .25 and it swings a larger prop, easy to tune, and cheaper. Plus they offer it in natural color in the .40 size which looks nice. I put it on a .25 cub that I intend to float fly with. The engine tached great all they way up to a 11x5 prop. Most importantly is its smooth idle so I don't have to swim after my plane come summer time. Speaking of weight, I did get a chance to pull my AP off the stand and weigh it. It came in a full ounce lighter than the .15 LA specs on tower. I know I am not swaying anybodies opinions on it. Just thought I would mention it as fact.

Matt Kirsch

My Feedback: (21)

Every discussion regarding OS LA engines needs this statement: The LA series was not designed for optimum performance. They were designed to be inexpensive beginner engines with the trademark OS reliability and user friendliness. You can't argue that the LA is not easy to start, isn't easy to tune, and doesn't make the airplane fly, because it does all three quite well.

thojo

That maybe true for most of the LA line, but the .15's are very competitive in SSC combat. They turn the 8x3 prop just as well as the Magnum's. There is alot to be said for reliability and user friendliness when you have 90 seconds to get your plane into the air...

mrfx2001

My Feedback: (2)

Mr. Wilson you have my curiosity up. What is a standard carb bore for a .15. And have you ever measured the exhaust, input and transfer port timing on the engines. Most sport engines are timed low. I have some numbers for .21 model boat racing but you need 60% nitro to run it with only two speeds. Fast and Very Fast.
Fred

Montague

Engine mods like opening carb throats, porting, and such aren't legal in SSC, but are fine in open and scale classes.