I have flown many RC Planes, mostly standard Brushless Eflite systems. I was looking into getting an F/18 or something from Nitroplanes but was told the break in was hard and very important. I dont know anyone personally that owns one so I dont know what I am getting into. What exactly entails this "break in"? I am wanting to get one of their plug and play versions and just stick my Spektrum receiver in it and fly. Is there more to it?

I'll let some of my more experienced fellow RCU members comment as to your choice of the F-18 for your first fuel model. Break in goes two ways. Take your engine out of the box screw it to the plane and do like some guys "break it in in the air". If you do you will never see the full power potential of your expensive engine. It may even have a short useful life. You may have difficulty getting it to idle and transition well. You may then abandon the fuel powered ranks disappointed. However, if you are patient and resolve yourself to the fact that you may run 1/2 gallon, 1 gallon, 2 gallons of fuel through it before it's really ready to perform - you are in the game. I believe that an ABC engine will require less break-in time due to it's prcision chrome bore. Feel free to correct me guys. Should your engine have a cast iron piston and steel cylinder liner a protracted break-in is advised. Don't look at engine break-in as drudgery. It's a great time to get to know your engine, it's quirks and needle settings for quick start-up at the field. I would run at least 20% lube on a new engine. I run 25% and 5 - 10% nitro. Run a prop that's on the small side in terms of diameter and pitch to keep the loads down on your new engine. Make five to ten short runs at 1/2 throttle with a very rich smokey mixture. Five to ten more with short burts to full throttle and back down. Remember to run small amounts of fuel for 3 - 5 minute runs. Let the engine cool completely between runs. I would, to be safe make 5 - 10 additional runs with the engine frequently at full throttle for more extended periods backing down the throttle occasionally. At this point you should be good to go if your engine will hold a steady full throttle needle setting and not warble or waver in RPM. Remember when starting your engine and setting the high speed needle, reach a maximum RPM listening to the engine pitch and then richen (counter clockwise turn of the needle) 1/4 to 1/2 a turn because your engine will lean out in the air and may cause overheating.

I'm sure you will get additional feedback from the guys - heed it. I'll be following this thread too.

Good luck,
Bill

I believe he is referring to one of the Electric EDF jets...

TxRCFlyer:

I've outlined the proceedure in one of the other EDF jet's here... I believe it was in the F-35.

More detailed info can be had by searching the Electric EDF forums.

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In a nutshell...

- You run the engine at a medium to 70% throttle speed for about 10-20 seconds then turn off the plane.
- You look for any areas on the EDF shroud that were rubbed by the fan.... you'll see some scratching created by the expansion of the blades.
- If you see none, run the engine at 100% power for about 10-15 seconds, and again look for scratching rubbing.
- Where you see this happening, fold over a sheet of sandpaper and insert it between the fan blades and the shroud.
- Manually turn the prop over to remove material from the outer edges of the fan blades.
- There should be about 2mm clearance from the blades to the EDF shroud all around.
- Once done take the fan out, and balance it on a magnetic balancer.
- While it is out, remove one motor retaining screw at a time, put locktite blue on it, and re-install. Repeat for the others.
- Put locktite on the shaft grub screw & re-install
- Balance the fan on a good magnetic balancer. This is very important!
- Re-install and perform the first few items again... check for any vibration.

2mm of gap is too much space to have inbetween your blades and shroud. You will definitely lose alot of velocity. on the flip side being to close is no good either. I strive for about 1-1.2mm distance. Now, take notice that this is in a "perfect" world. Given the fact that our ducting is not aerospace engineered for the most part. Now the cross sectional area of the intake needs to be the same as the exhaust. Unfortunately this doesnt work all the time. Most of out intake ducts are divergent. While the exhaust is usually a convergent meaning it shrinks. This does increases flow across the fan and reduces pressure at the inlet. It still causes a loss of flow at the blades, so try to strive for a smaller area of gap between the fan and shroud to maximize velocity and minimize air loss.

Yup, 1 - 1.2mm would be optimal.

The problem with these small EDF's is that often the shroud is glued in and out of round. The material is not very stiff and easily deformed by hand.

So 1mm on one side of the fan blade might mean 2mm on the other...

That is why it is important to run up the fan and look for any rubbing areas, and work from there. If the fan rubs too much the motor will build up heat ( the friction prevents movement ) and it can overheat or overdraw the ESC... IN THE AIR!

Once the clearance is established, the fan should then be balanced, re-installed, and another search done to see if there are vibrations or rubbing issues.