Airbourne in Japan

My Feedback: (3)

hi, i am thinking of getting a multiplex twin jet and putting brushless motors in it. i was wondering first what the max prop size is. i was thinking of getting another warp 4 turn motor as i have one in a plane i'm pulling out. with something like a 4.7x4.7 prop it pulls about 15 amps. also is the battery compartment quite big ? i would be using something like my hyperion 2500 mah 3s 20c. what brushless setups are you guys using ? thanks

Kensonic

Airbourne in Japan,

I just setup my twin Jet with two Warp 4 BL4-15-5 (5-turn speed 400 sized inrunner) using two Castle Creations Thunderbird 18 Brushless speed controllers and 2 -2100 mAh 3S Lipo batteries. I started with two APC 6.3x4 combat props and while they did clear, there were heavy and difficult to get to run smoothly (prop balance issues combined with the weakness of the foam). So, I added carbon fiber strips around the outside of the foam motor mounts and switched to Master Airscrew 6x4 3-blade propellers. The clearence is better, and they have better dynamic balance. Also, I was able to get a normal and a pusher version of these props and then run the 2 motors opposite so as to cancel out the torque. On a brushless motor you can reverse the rotation by swapping two of the control wires and there is no efficiency loss. This works great as there is NO tendency to rotate on launch due to prop torque. I went for thrust and not speed, so my tops out at 50 Miles Per Hour, but it can really climb. This setup draws about 11.6 Amps per motor which is no problem for the motors, ESCs, or batteries. After a flight everything is cool. After a typical flight of 8-10 minutes, I have only used about 1000 mAh from each battery (1/2 of the capacity)!

tIANci

Airbourne - how about a single big motor set up? Seen a couple around and it looks kewl. Saw one with a gear box turning a nice big prop of about 12" I think

Airbourne in Japan

My Feedback: (3)

naa, i want to stick with the twin motors, this is my first twin to fly consistently well. i think i'll probably stick with the warp 4 turn motors, but maybe a 3 turn version in the future

carlrich

I bought two Nippy Black 1608-160 motors for $15.90 each as they are currently on close out from Hobby Lobby. Intalled with two cheap towerpro 25A escs at $24 each and am using 6.5x6.5 graupner speed props from hobbylobby. Using one 2000 mah 15C kokam pack that puts out 30A and is 120 degrees F after moderate to hard 6min flight. With 3150 15C pack it worked even better. I am getting right around 100mph and really nice vertical. Not quite unlimited but it really goes high on vertical while I make it spin like crazy. Very fun plane! Faster than my hopped up Alpha Sabre with 2025-5300 himax on 3 cell 2100.

Carl

jonnyjetprop

My Feedback: (3)

I'm using Mega 16/15/4, CC Phoenix 25, APC 6x4 props and a single 3s3p TP prolite. Been flying for two years now.

John

nomorebikes

Hi Carl,
I read that you used the NB 1608/160's in you Twin. I'm really curious how you mounted them. I bought a twin awhile back and took advantage of the same sale at HL, ending up w/ four of the motors. I'm still fairly new to this stuff and am trying to soak up as much knowledge from you "seasoned" guys as I can. I appreciate any info you can offer.

Thanks Carl!

JC

carlrich

JC, I positioned the NB motors w/ mounts into the motor area and made a mark on the back side of the motor mount at the point I wanted them mounted. I recessed the motor into the motor area to keep as much weight forward as possible so I wouldn't have to add much weight to the nose of the plane. The motors aren't that heavy but every ounce counts. I've tried all the APC props and found 6x5.5 the best but it doesn't pull as many amps as I'd like and thus is not giving all the performance the motors are capable of (2100mah 15 to 20C pack is fine). For considerably faster performance and vertical you'll want the Graupner 6.5x6.5 props from hobby lobby. This set up uses all the power available and you'll want 3000mah 15-20C pack or you'll really heat up a 2100mah pack and not get as much performance. www.commonsenserc.com has a 3150mah 10C pack that actually worked really well. MOst battery co. lie about their performance but I think CSrc underrate their packs.
Check to make sure you have the correct prop adapter. I think I ordered two from HL with the props.
I then cut out two pieces of 1/8" plywood to be the same depth as the opening where the motors go in the twin jet. I made them a little bit wider than the opening and cut small channels on either side for this 1/8" rectangular piece of ply to fit into. You'll find you need to round off the corners of the rectangle that is going in first as the motor mount area is rounded. Make sure that the channels are straight up up and down with the plane and that they are parallel with the groove in the bottom that shows where the standard 480 motors are to end. This keeps your props pushing straight back and not at an angle. Slide ply into position and mark outside edges where ply meets all foam. Mount motor so that top of motor wont rub on top of motor housing foam. I cut out rounded area on both sides of foam to allow motor to recess without rubbing. I left my escs exposed to the air as they are only 15A escs I think, might be cheap 25A tower pro escs I can't remember at the moment. Anyway I mereley super glued the esc casing to the bottom of the wing and superglued (C/A thick) the wood into the channel. If you land hard the motor and wood former will come out until you've superglued into place several times. Now mine wont come out after about 2 times of reglueing back in.

Get the bigger battery and the Graupner props. This thing is smoking fast. I have an Alpha Sabre that is supposed to be 89mph with the setup I've duplicated. I have an awesome 2100mah 15C pack from CSrc in it and it may be faster than the 89mph. This Twin jet is just as fast or faster with the 3150mah 10C pack. The twin will spin something crazy while ripping up vertical! The vertical is not forever but it is fast as stink while going vertical for a very nice climb. There is no drop at all on hand launch. It is an awesome plane for the little $ invested!

Carl

carlrich

JC, If I am successful there will be 6 pictures attached here.
I ended up needing to put wooden control surfaces in place of the foam ones as the foam was deflecting under high speed. Cheap and easy. Buy wooden aileron stock from hobby store and use a razor and sand paper to create an angled front instead of the rounded front supplied on wooden aileron. Use hinge tape to attach.
Two other places I use the Nippy Black $15.90 motors.
72" span C-47 from Polks hobbies $100 for whole arf
52" span P-38 from Nitro models $129 for ARF.

Carl

TOMAPOWA

My Feedback: (1)

Hey JonnyJetProp,
What size LiPo you using (maH) ?
I'm almost finished with my Twin-Jet and all I can say is "WATCH OUT". I have installed two cheap-o 3000rpm brushless motors (Walera 380S), spinning two 5x5 APC props using two PH-35 amp controllers and I plan to use two 2100maH 3S LiPos (11.1v, 4200maH). I'll try to post some pics soon.... It appears a little heavier than I like (due to 2 large brushless motors mainly) but I'm sure it'll go FAST! (my main goal).

Tom

Sluf7

Mate had one with kontronic system in it was clocked at 220kph.[8D][X(]

Then converted to EDF AP900 fan 650 watts here's he video http://www.wattsup.co.nz/phpBB2/view...t=45&start=30;)

TOMAPOWA

My Feedback: (1)

Awww... No video of that 200+ run ????
[&o]

By the way, I posted some build pictures here...
http://www.rcuniverse.com/forum/m_46...anchor/tm.htm#