breaking in a new engine

It really depends on the engine. Some ringed engines don't gain enough reliability until they have a couple of gallons through them. Many of the ringed Supertigre engines are like this.

Most modern ABC (ABN) engines can be flown after a couple of tanks to seat all the parts and get the basic settings done.

I agree with Paul.

You can break-in ringed engines in the air, but how many people have a model set up to facilitate such a process?

During break-in, a ringed engine will not be producing anywhere near the power that it will produce once it is broken-in. How do you fly-in such an engine on a model that needs all of the power that the engine can produce once it is broken-in?

Simple.

I used to fly Bridi Trainer .40 and .60 models quite a bit. For a long while, they were terrific fun fly models for the type of informal fun flies we used to have, in the "olden days".

A good friend of mine, Syd Clement, showed me his modified Bridi Trainer 60 one day. He had hacked off the nose material in front of the firewall and installed an Edson Universal Adjustable Engine Mount along with their tricycle nose gear accessory. The day that I saw Syd's model, he was running a rear exhaust Rossi .60 on its side with the pipe going down the side of the fuselage under the right wing panel. This thing was so fast, it was scary.

In addition to modifying the nose, he also moved the vertical fin forward. The old Bridi Trainer .60 did not have a full length rudder as did the Great Planes version that came along later. The top of his horizontal stab was exposed and the bottom had added triangle stock for reinforcement. He had inset a square of 3/16" plywood into the horizontal stabilizer, right behind the rudder. He then drilled and tapped the piece of plywood with 1/4-20 threads. Then strenghened the threads with CA and ran the tap through several more times to clean them up.

The idea was that he could run some really large engines (heavy Rossis) by simply mounting various metal Prather Spinner Weights on the horizontal stab with a nylon wing bolt. Voila, CG adjustment made easy.

I copied Syd's idea and flew the dickens out of that model for years. One day, I was curious and wanted to see how the Trainer .60 would fly with an HB.40PDP in place of the usual sixty sized engine. I removed the tail weight and the model balanced perfectly. For the first time, the Trainer .60 actually flew like a really good trainer. It was not underpowered at all and was still a brisk performer.

If you can find a model that will fly well with a .40 and is large enough to absorb the thrust of a .60 during break-in (nearly the same), you have the means to break-in a ringed, two-stroke .60 (or four-stroke .90) in the air.

Flying a ringed .60 size engine slobbery rich (necessary) in a sixty sized model requires quite a bit of piloting skill and lots of good luck.

Still, I would set up the engine on a well elevated engine test stand on the ground in order to spot any problems with the engine while running the first two tanks of fuel through it.

Ed Cregger

There are as many answers to this question as there are people who d

"their" thing. Me, I have a half full tank (carb on center with tank), run rich, lea it out a bit, run rich until it four cycles, lean out a bit, etc. I d this two or three times until "I" think it runs ok. Then just fly, a long as I know that the engine will not die on me in flight. When i is exactly "run-in", I have no idea. The worst time is trying to set u the needles correctly, especially the low-end one. Usually takes m about four or five flights. These engines just do not run the same "i flight" as "on the ground". It is very rare for me to have an engin die on me in-flight. So in the end, follow the mfg suggestions and yo should be OK. Why half full tank? Because "I think" that the engin runs different if the fuel tends to siphon into the carb

-- indoruwe

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I lean in your direction on this one, Gord. And I do agree that engine brand and model do make a difference in how I handle the break-in procedure and its duration.

There are some engines that I mount up and fly, but they are rare.

Ed Cregger

I prefer to break them in on a test stand using the manufacturer's guidlines. I see too many students coming to the field with brand new motors that are not broken in and too many times the results are not good for the student. I have also seen too many dead sticks by experienced flyers with brand new motors. Some motors like OS will generally run well right out of the box but I still like to break 'em in on my test stand. Once they run and idle well, bolt them on the 'plane and fly with confidence. Additionally, if you bolt a well broken in motor on to a 'plane and it does not run well then you know where the problem is. Gord Schindler MAAC6694

I always use a test stand to run at least two tanks of fuel through any new engine before mounting it in an airplane. I cobbed up a cheap test stand using a plastic ajustable engine mount, but found I used it so much that I finally sprung for a nice machined-aluminum adjustable stand (J'Tec) that would hold a very wide range of engines (1/2A to 2.5).

Break 'em in right and you'll save a LOT of heartache at the field!

Good flying, desmobob

IMHO, It's best to use a break-in stand and follow the manufacturer's recommendations. With the engine on a test stand you can easily adjust the settings and become familiar with your new baby. Troubleshooting is much easier. When the bird is in the air you can't adjust the mixture and a lean run, especially with no castor, can ruin a good engine. Furthermore many professional engine gurus and ABC/AAC engine manufacturers recommend 2-3 minutes running just a few clicks on the rich side at WOT followed by shutting the engine down and allowing it to cool off before the next run (thermal relief). Dub Jett's engines are among the best worldwide so check out his recommendations here:

Click on Tech Specs & Instructions. Kinda hard to follow his recommendations with the bird in the air. ;-)

It depends on the kind of engine.

My experience has been that ringed engines and four strokes require some time on a test stand to get a good result, and I usually use the mfgrs recommended prop size.

ABC or ABN engines I break in on the plane. As soon as an engine will idle without quitting or moving the airplane and hold a peak without sagging I back off peak five or six hundred rpms and go fly. Sometimes it takes a tank or three to get to this point, sometimes a tank or less. I like to "underprop" these type engines for break in, going down an inch in pitch or diameter or both from the mfgrs recommended size.

I also like to add two or three ounces of castor oil per gallon of break-in fuel for good luck. This can help prevent permanent damage in case of an accidental lean run.

Texas Pete

It sounds like we use similar techniques, Pete.

OS's "new" FL-70 is interesting in that it is the only four-stroke that comes to mind that does not utilize a piston ring. This would be perfect for folks that do not wish to bench run their engines, but instead fly them in on the model. I haven't ran mine yet, but I'm looking forward to doing so as soon as possible.

Ed Cregger

Been flying RC for 25 years. Started out with trainer OF COURSE! Went to pattern, then scale now ducted fan. I put an engine on the plane and fly it! Never had any problems at all.

First few flights I would run it a little rich and after 5 or 6 flights, set the neddle valve and have fun.

BTW I always run synthetic blend fuel not castor.

n 21 Oct 2005 19:44:02 -0700, "seany1124" wrote:

Agree. Works for me. Just set it rich and fly. Much better in my opinion than annoying every one at the field with it droning on and on tethered nearby. Or worse the neighbors who find it rather annoying in spite of the leaf blowers, edgers, lawnmowers they are using.

Red S.

I had several ringed engines that If I followed that advice, they would more likely be broken rather than broken in! Some of these (Supertigre) didn't become reliable enough until a gallon or more went through them. Then they were the strongest of the bunch!

As others have said , depends on the type engine.

Ringed engines are broken in differently than non ringed engines such ABC , ABN and so on. ABC , ABN and the others with a tapered liner need to be run hotter. There is more heat generated at the top of the cylinder and heat is needed to expand this to make room for the piston to freely move up and down. You can actually ruin these type engines by running too rich since this would not create the heat needed for a good piston/liner fit. Although I prefer bench running these engines , many get by just fine by breaking in during flight after establishing a good idle and high speed needle adjustment. I used to use my finger to constantly monitor head temp but I now have a nice little infrared temperature gauge to do this. Gets a very accurate temp when shot right into the glo plug area , and , sure is easier on the finger LOL.

Ringed engines normally require more break in time and richer needle settings. I would definately recommend bench running ringed engines as the others in the group have said. I will not fly a ringed engine without a decent run in on the bench. Also , it's more important to closely monitor head temp on the ringed engines. I would recommend anyone get a temperature gauge for these engines. They can be had for less than $30 US.

The main thing , IMO , is to follow the manufacturers instructions. This will pretty much dictate whether or not the break in process can be completed in the air or on the bench. As some others pointed out , you just can't reach up there and change the needle setting while flying around .