crakey

A 4 cell lipo (I believe) is 14.X volts, way above the 11.x volts that the ESC can handle...so don't use the 4S lipo-ever. Anything that is 3S and has the C-rating near the stock Apprentice battery will work.

-Update on larger props-

I flew a 12x8 prop and was amazed at the performance, I still got20 minutes of flight time and when I landed after some real 100% throttle runs, the ESC was cool to the touch, very cool. Even the battery, which is usually very warm after a flight, was ambient temperature. The performance was amazing, it took off in 8 feet and climbed completely vertical to about 150'. If anyone can measure the amps, I would be interested to see what the motor/prop pull in amps at 100% throttle with a 12x8 or a 11x9 instead of the stock unit.

As for inverted flight, Iused to be able tofly mine inverted for 5+ minutes in large circles, or outside loops (with the stock prop).

Question: Lately, when I have flown and got some high speed (like in a dive), the plane "grabs the air" and does a nasty climb (with no elevator input), putting massive stresses on the wing.I saw it lift off the fus. today about 2". Scary. Also, now, when I fly inverted, even with full elevator, it will NOTstay level, it "climbs" towards the ground. Are both of these related to COG? Dr B, have you ever had to add weights to your plane? Where does the battery sit in the compartment- there is a 1/2" space between the battery and nose side or tail side of the compartment.

Also, I strapped a GPSto the Apprentice with the stock prop and hit a max speed of................................................ ......62mph!I can't do that now, with theproblems at high speed.
Thanks for your help guys!

Dr_Bojangles

Abso-freaking-lutely! If you’re flying your plane without checking CG, you’re rolling the dice every time you launch.

Take a trip to the Arts and Crafts store. If you don’t want to be seen going into the Arts and Crafts store, send your wife, but get a block of foam-rubber (two-inch thick or so). You’re going to use it to keep your battery from sliding around inside the fuselage.

Now, build a CG Machine – it’s cheap and easy. A block of wood with a couple of wooden dowels glued into it. You just have to make sure the dowels are square with the block – use a small carpenter’s square.
www.bobvila.com/images/HowTo/IHouse/WorkshopGarage/Combination-Square.jpg


Click here to see my DIY CG Machine:
i196.photobucket.com/albums/aa62/tkrahlin/RC_Plane/Motor%20Swap/Balancedwith15-grams.jpg


You can’t be sure until you balance your plane. However, if it were the CG, it would be tail heavy even when upside-down and wouldn’t climb toward the ground. I’m not sure, but it could be that big prop. That’s a pretty big screw cutting through the air and maybe it’s twisting the plane. You ever get a drill bit stuck?

rhampton

My Feedback: (66)

You have some really good advice Dr. Bojangles. I'm sure everyone here appreciates your help.

Reggie

crakey

Man, Ijust wrote a huge post and the battery died on the laptop.... go figure.
Dr. B- I was just asking if you ever need to balance the Apprentice with weights, my CG has always been really close to perfect.
The cause of the violent climbs was the entire battery compartmentcoming loose- I am SOOO gladI caught that.
Where do you install weights? Do you go with very small weights in the furthest end?
Oh yeah, I am just fine with going into an Arts and Crafts store!They have the best paint selection around! Did you shim the batteryto thefrontor back ofthe plane?

I understand the VERYbasics of the screw analogy, but I dont understand how it could pull "up" only at high speeds.

Thanks a lot for the help!

Dr_Bojangles

Yep! Even though I’ve had that happened to me too, I didn’t think about it.

Yes - The farther alway from CG you can get, the less weight you have to use.

Now that you put it that way, a properly trimmed and balanced plane should fly straight and level at about 50% throttle. Accelerating puts air over the flight surfaces quicker and will naturally produce more lift.

dribbe

This is not correct... You should have a look at the specs of the EFL controller.... In fact the BEC's in the 30, 40L, 40, and 60A EFL controllers are switch mode, and can deliver full current at all approved input voltages. The BEC in all but the 30 is VERYstout.

Of course more than the controller is involved in running 4s... it would need to be propped for a current similar to the 3s setup... just more wattage.
Be sure to make the appropriate programming changes.

http://www.horizonhobby.com/Products...rodID=EFLA1030

The 40 and 60 from EFL are great if you are adding more servos for flaps or something like that.

David

Dr_Bojangles

My older son and his family came by yesterday and one of the first things we do when they visit is take my 8-year old grandson to the local hobby store. Toward the end of the evening, my son told me to come and take a look at Kam’s hanger. He had parked all him planes with mine.

crakey

Sorry!

That's what I get for talking without looking anything up.
I didn't think the ESC was that versitile on a RTF trainer. I like the Apprentice more and more each day!

Dr_Bojangles

It’s sure great to see you here, Dave.

Have you been following the thread? We hope you stick around…

I was fortunate to have the benefit of a knowledgeable salesperson at the LHS. I almost went with the Super Cub, but wanted a TX that looked and felt like the interface I was using with the Real Flight G45 simulator. He showed me the Apprentice and pointed out the versatility of the electronics and how they could be used later in other models.

I bought -eBay auction- a few more Apprentice fuselages and parts (actually, a lot of parts). After Hot-Rodding the Apprentice, I bought a Sea Fury ARF and used the radio and ESC from the Apprentice to offset the cost of the build. It’s my second plane and my first ARF, low-wing, warbird. I just flew it for the first yesterday and I can’t wait to take it out again today.

Tim

crakey

$3 upgrade to Apprentice:

12x8 prop

I cannot tell you how much fun this prop makes the plane! The overall speed is increased, climb rate is out of this world, and Idid a prop hang with a trainer airplane! I have been careful notto go completely 100% power for extended periods of time, and I have also checked the ESCfor high temps, and it is cooler than normal (I don't understand this).This only negative is that flight time is decreased by about 2 minutes (down from 18 mins at 80-100% throttle).

****If anyone has a watt meter andsome time, could you please tellattemptanampdrawwith a 12x8 prop on the standard Apprentice motor and ESC?

-Clayton

crakey

[quote]ORIGINAL: Dr_Bojangles

Props-Shmops! I threw a Power-25 motor in her with a Castle Creations Phoenix-45 ESC. Video here:
http://www.youtube.com/watch?v=zhAHWLrXv84


Hey Tim!

I also just installed the Eflite Power 25 motor and a Castle Creations 60 Amp ESC.... can't wait to fly it tomorrow.
-One question: on the motor mount, where do the red spacers go? Did you still use them with the Power25 motor? Well, that' 2 questions.

Thanks,
Clayton

crakey

That Apprentice looks brand new!No dirt marks from impacts or weeds hanging from the gear

Dr_Bojangles

Yes, you have to use them - put them back where you found them.

crakey

Don't know where they came from! I can't find a IPB anywhere for it, either!

Dr_Bojangles

There are four holes that hold the motor mount to the firewall.

The red spacers go between the firewall and the motor mount on the top and bottom holes on the starboard side.

They are used to angle the motor up and to the left to counter-act the screwing effect of the prop.
See thrust angle: www.rcuniverse.com/forum/m_6306347/anchors_6306347/mpage_1/key_/anchor/tm.htm#6306347

crakey

Thank you! The plane flies great with the new motor setup... have you tried a lower pitch prop on the 25 motor yet?

Dr_Bojangles

Not yet - last time out I flew the heck out of my new Sea Fury. That's a real kick and diffrerent from the Apprentice. Not better, mind 'ya, just different.

JHMBB697

i think i've run into the same problem you did. do youhave pictures of your "overhaul?"

smalls_sandlot_11

i just bought the apprentice, i am loking for another spair battery, the existing one is a E-Flight 3S 11.1v 3200mAh can i use a Turnigy 11.1v 3300mAh 3S 20C Lipo Pack ??

JHMBB697

i dont see why not...but thats me

mickvk

My Feedback: (1)

Well I don't have the exact information you want, but you may find this interesting: The Great Planes Rimfire 35-48 840KV (which I think is pretty close to equivalent to the PnP840) with an 11x7e, at 0MPH, full throttle draws 30A and produces 49 oz of thrust. The 12x8e prop draws41.6A and produces 63 oz of thrust. According to Motocalc.

ThisIsKush

i've been flying this setup for a while now. the power is unreal. climbs straight up. i literally take off in 10 feet. and believe it or not i haven't noticed any less flight time w/ the standard battery. maybe because it climbs so fast i have more glide time. it's so powerful now, i was able to upgrade to a much bigger and heavier battery (3200 to 4500) w/ hardly any difference in flight, and much more flight time. this is the setup EVERY Apprentice owner needs. i swear by it. i would never go back to the stock setup after experiencing this. and get it from this site. shipping for anything and everything is $2, they have all high quality stuff, customer service is awesome, and they get it out immediately..

Heads Up RC
- 3548-09 Outrunner ($29.95)
- 40A Power Up Brushless ESC ($31.95)
- 11.1V 4500mah 20C 90amp LiPo (optional, but much longer flight time. if you climb and glide over and over, you can fly for 35-40 min on one charge no prob)($59.95)
- SG90 servos (highly recommended to upgrade these for your ailerons. the ones it comes w/ are cheap.) ($4.95 each)

roflmcwaffle

thanks for this post!
I just purchased my E-flite Apprentice and am taking it out to fly this weekend, all these tips and ideas are greatly appreciated, thank you!
Quick question, the charger that comes with it has only alligator clips to charge the battery. Do you guys just hook it up to your car battery or can i find an AC adapter for the charger?
thanks

LarryV

When I get this type of charger I cut the alligator clips off, replace them with a male plug that fits into the cars 12v system (cigarettelighter) To charge at home I have a 120 to 12 v converter that accepts the same male plug.

mickvk

My Feedback: (1)

I also like to do that or use a "power station" that has a battery in it. The inverter, jumper, compressor, light, etc comes in handy for other things and the plug can be at my flight line or in the back of my car...

www.amazon.com/Stanley-DPS109-Digital-Portable-Station/dp/B001U0FDAQ