NVA Range

Putting the first flights on my ARF with LA .40 and trying to get the engine running good. First flights were too rich to do manuvers of course then, 1/8 turn leaner every flight.

As I got closer to the setting I noticed how heat plays a part. If I take a slow walk to the handle the engine 2 strokes more in the first half of the pattern untill it cools. OAT was 65 so might be different in summer.

Never got a clear 4/2/4 and, I'm not really sure if it's important to make it do that trick, I just want enough power to pull through the manuvers but not run away.

After the first runaway flight I noticed there seems to be about 1/4 turn between too rich and too lean. Is this typical? Is there a way to extend this range to maybe a 1/2 turn?

Here's some set-up info:

ARF Carndinal
OS LA .40 with tongue muffler
Zinger 11-5 wood
3 oz. uniflow tank
10 nitro, 20 castor
OEM venturi with PA NVA

I'll have to pop the head to see how many gaskets or if it's cut for less compression. Anyone know how many CCs or, a good compression ratio for stunt?

I really think that you'll be happier with an 11 X 4 prop...preferably a Power Point if you're into wood.
And a 2-4 isn't where that motor likes to be....try a wet 2 cycle.
3 ozs. should do the beginner pattern.

See Ya

I've never gotten what I would consider a great run from an LA40. It is as far as I'm concerned not in the same league as the LA46.
I've had one for 3 years that has had up to 3 gaskets, 4 different fuels,2 different venturis, and lots of prop experimentation,Also tried both stock and tongue muffler, pressure/no pressure.
Best that I get out of it is 1/2 flight with a perfect run and then a continuous windup from then on. I've done tank shims,never had the plastic backplate /remote NVA on it, have used Thunderbolt,Fireball, Merlin,Enya,Rossi,Sig,Fox plugs all to no avail.
A lot of fuel has gone through this motor and it still looks and feels as new as it was 3 years ago. I've never had a lean run believe it or not but I've also never had a consistant run from beginning to end. This seems to be the only motor in my stable that dosn't respond to most of the obvious cures.
Strange that in this area there are tons of FP 40's running quite well, mine included but I really do not see anyone else even trying to run the LA. Perhaps Peabody's admonition that they don't run well in Jersey also applies to Pa,
Interesting fact is that if you set the NVA actually a little too rich to do the maneuvers it will hold that setting perfectly the whole tank. One or 2 clicks farther to get into the correct setting and your problems start.
Perhaps some of you have an answer that I've overlooked.
Dennis

I thought that 11-5 might be too much for that engine. I'll cut it down to 10-5 while I'm waiting for my TF 11-4 power points. I was thinking if you load the engine down too much it gets sensitive on the needle.

The best flight I had Sunday was breaking in and out of a 2 stroke. If I go full 2 stroke I might have to make a smaller venturi to slow it down. When that thing leans out at the end of the tank it starts pullin' like a rat racer.

Giffy,

Careful what you wish for with a real broad needle. Personally, every time I hear someone bragging of not having had to change their needle setting over a period of months I kinda wonder if the thing is really dialed to perfection, or is simply within a fairly broad range of acceptable.

I suspect the latter situation applies more often than not.

While none of my CL Stunt engines are tuned to every cloud in the sky, I find it best to be operating with one or two clicks--or the equivalent on a non-clicker NVA-- being the difference between *the setting* and too rich or too lean.

Uh, that means not being off enough to bail on flying a full pattern, just not the ideal setting, to be corrected prior to next flight.

For what it's worth, few things serve to build more confidence at a contest than doing a test flight, flying the full pattern, but seeing engine is just a touch rich, going in one click back in the pits, knowing that sucker is dialed and ready to go.

I am one of the leave the needle alone crowd. Lately, I've been flying a Tower 40 in OTS. What I go by is how many laps I get after the pattern is finished. If the lap number goes up or down more than a couple of laps, I make a small needle adjustment. I flew at the VSC at 2500 feet at the same setting that I fly near my house at @1200 feet. I flew the same setting at the Dallas June contest. I think I fiddled with the needle some before the Labor Day Dallas contest. Then left the needle alone to fly at St. Louis at @500 ft. and havn't changed it since. I think Dan is right about being in an acceptable range, as I have flown the airplane OK with settings somewhat leaner or richer.

Back when I was flying Foxes on relativly heavy airplanes, I did some needle fiddling based on weather, altitude, etc, because I just didn't have that much margin of power.

Well, if your using the stock OS remote needle....your hooped.....they will never work....they all leak....You will notice it when you start to lean the engine out and it just won't run consistant. They leak a very small amount, when your rich, its not as noticeable.....when you get to where you want to lean the engine to a wet 2 cycle (where it should be), that is when it will run away as soon as the load starts. We have run across this numerous times with the stock OS remote needle.
I tried and tried this set-up with an LA 46 and gave up. Went to the tigre needle assembly in the venturi (where it should be) and never looked back.
We had this same scenario again this last summer with no luck after repeatably mentioning to chuck the remote. The only change we made was a tigre needle and away it went....Perfect engine runs....
Take the stock OS needle (remote) and sell them on ebay....Lots of rc guys buy those things....

>Well, if your using the stock OS remote needle....your
>hooped.....they will never work.

Think he beat you to the draw on this one, Rob.

"OEM venturi with PA NVA"

Hey Giffy,
I also have an ARF cardinal and I'm running the same set up.OS LA 40, 11-5 prop. It seems that what you are experiencing is pretty typical with this motor. Not a whole lot of leeway on the needle. I've got mine running really consistent but I've also made some modifications.I added another head gasket, got rid of the plastic backplate and junction box that comes stock and got a back plate from an FP 40. New spray bar and venturi so the fuel is direct (venturi from Muggleton). I get a good 4-2-4 break. It's very finicky. Early morning no sun runs different than 8:00 AM with sun, I have to needle it the warmer it gets. RPM prior to take off roughly 8600. 5% nitro is all you need and you'll get better mileage, with a 3 oz. tank I dont think you would be able to complete the pattern...are you? Anyway this is what I got going and its working good. I love my Cardinal ARF!!! It flys really well and jones to fly every day. Good luck and happy landings.

There are two things I see here as red flags--3 ounce tank and PA needle valve. What venturi is on the engine? I have to ask because even OS won't know the answer. They just seem to be cleaning out their inventory these days. If you have the original .265 venturi on it with that needle, the venturi is too small. And that may be why you are getting such good mileage. I always say the .257 on the 25 is too big, but you would be running the equivilent of a .245 on that 40.

You should be running at least a .287 with that needle. Maybe a .290. Maybe a .300. This is a blocked boost port engine. Open the venturi and you will have more power and a lot better ability to needle. Of course you will now also use more fuel (remember that 3 ounce tank? Too small.)

I will agree on not liking the rear needle, but you already solved that. You may have a problem with that plastic back plate loosening if you haven't changed it out.

There is also a deck height issue here in that this is one measurement that will vary from engine to engine and can affect one, but not another. That aside, the bore, stroke, and timing are the exact same as the FP. There is no reason there should be issues here of the engine not running except for some of the things I mentioned above.

I use the 10/20 fuel because, it's the spec racing fuel I have left over from racing. I guess I could cut it in half with FAI fuel to get a 5/20 mix. I'm almost certain I could run 15% castor in that engine with no problems.

Does less nitro make it less touchy on the needle or, is it a balance between nitro and compression?

I can do the beginner pattern, running slightly rich, with the 3 oz. tank. From signal to landing is about 5 minutes. I wish I knew how long they give you to complete the pattern.

I have ran 10% nitro all the time in my LA40 with 23% 50-50 lube Coopers.I have a FP metal back plate and OS venturi needle valve assembly in a .280" venturi.I have most the run time on a 11x4 APC but have run a 11x5 APC also.I run a wet 2 stroke with a slight burp in level flight .As for tank a sullivan rectangle 4oz tank plumbed uniflow.I did add one extra head gasket which made the motor very consistant from start to finish.I also run a 4 stroke plug.This combo gives me 6min 50secs of run time so the pattern is no problem.The needle has about a 2 click range on either side of perfect to work with,any farther and something is wrong.This fall I was starting to have a problem and it turned out to be a leak around the outside of the venturi.(new O ring time)With 200 plus flights on the motor it is still going strong.They are a great motor at a bargain price.

>Putting the first flights on my ARF with LA .40 and trying
>to get the engine running good. First flights were too rich
>to do manuvers of course then, 1/8 turn leaner every flight.
>
>As I got closer to the setting I noticed how heat plays a
>part. If I take a slow walk to the handle the engine 2
>strokes more in the first half of the pattern untill it
>cools. OAT was 65 so might be different in summer.
>
>Never got a clear 4/2/4 and, I'm not really sure if it's
>important to make it do that trick, I just want enough power
>to pull through the manuvers but not run away.
>
>After the first runaway flight I noticed there seems to be
>about 1/4 turn between too rich and too lean. Is this
>typical? Is there a way to extend this range to maybe a 1/2
>turn?
>
>Here's some set-up info:
>
>ARF Carndinal
>OS LA .40 with tongue muffler
>Zinger 11-5 wood
>3 oz. uniflow tank
>10 nitro, 20 castor
>OEM venturi with PA NVA
>
>I'll have to pop the head to see how many gaskets or if it's
>cut for less compression. Anyone know how many CCs or, a
>good compression ratio for stunt?
>
>Thanks,
>Giffy

1) Try an 11-4 APC. More revs, more thrust, less load.
2) Maybe the tongue muffler is too restrictive? Drill out holes or remove screws.
3) I've not run a .40LA yet (soon, CardinARC), but Mike Haverly and Jerry Day have run them, with front NV and homemade venturis. Run fine. Not sure what Mike's setup is, but he did say it ran exactly like the .46LA (very well). I know we put an 11-4 APC on Jerry's, because it was mine.
4) I might try adding some Klotz to bring the oil content up to 23%/25%. I ran my .46LA on 10-29GMA (all castor) and had no complaints, but used the Macs Muffler on it. Then changed to 10-22GMA, and I couldn't tell the difference. Maybe I'm just insensitive. Jim Johnson tried 10-29 and could not make it work on his .46LA...not sure about his muffler, maybe tongue muffler, but probably running richer. 10-22 fixed that to Jim's way of thinking.
5) Check the venturi bore. Maybe it's too small. For the .40, I'd think .275-.285 would be ok. I tend to use large-ish, but then tend to also use a Bruline filter. The PA/Randy Aero NVA is da bomb!
6) Pressurize the crankcase with an airhose (at maybe 5psi) and check for leaks at the backplate, backplate screws, venturi base and NVA nut/flange with soapy water.

You don't have to cut on these things to make them run real well. Did you replace the backplate with an aluminum one, and a new gasket? Did you take it all apart, maybe put the rod in backwards? I firmly believe in getting any engine all "setup" before ever running or flying it. Less hassles at the field, and MUCH less chance of dorking your model. I have seen a glowplug change (to Thunderbolt or other Ohlsson product) make magical improvements. Steve

"I've been running my LA .40 with plastic back plate and no problems so far. Giffy"

I copied and pasted the above from Giffy's response on the Tower Backplate Thread started by Ian Russel (aka Rustler). Either the problem has been solved, or it's been forgotten. If Giffy has solved his .40LA problem, it would be very helpful if he was to post his findings. Steve

I want you to understand, I don't have a problem with my LA .40.

I just want to know if there's a way to make it run in the "zone" with a wider range of needle valve adjustment. I want it to be easier to set so I don't waste all those flights getting a perfect setting.

I think one difficulty with this is the heat climbs so fast in a narrow rpm range between 4 stroke and 2 stroke which amplifies any change in needle setting.

When I find a prop I like I will have to keep notes on the O.A.T., where the needle is set and ground rpm.

Ah. Well, the heating issue could easily be cured by less pitch, more free flow muffler, and/or more oil in the fuel. Set the NV for peak, back off 1,000 to 1,500 rpm, and launch. Pitch of 4" is about right, maybe even a bit much, depending on wingloading, altitude, ambient temp, etc., with around 10k launch. Steve