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Mar 23, 2006, 09:23 PM
Rochester, NY
JustGoFly's Avatar
Build Log

TwinJet Build, Tips and talk

I wanted to wait until I completed the maiden before posting the build thread. Wise move since it took a few weeks after completing the build that the weather broke to enable a maiden.

My setup is all components:
Dual JGF 450T Brushless Motor
Dual JGF 32 amp ESC's
Dual JGF 2100 15C 3S, LiPo's
GWS HPX ParkFlyer Servo's - .10 fast and 56 oz of torque
APC 7x7 Prop
Lots of Carbon Fiber

Maiden went very well. Plane took off with a 20 degree climb at 1/2 throttle. I actually backed down on the throttle once I got it up some. Trimmed it nose down some otherwise it flew perfectly. Switched to 60% dual rate with 50% Exponential and flew extremely well around the field. I flew very conservatively since this was the maiden, but I did tip the nose up and slam the throttle to climb quickly and without hesitation. I didn't fly full throttle for a fast fly by YET, since I wanted to make sure this survived the maiden and any attempts to push it was caught on video. Video will be posted once I fly with the guys at our flying field.

CF Tube and CF Rod to hold on the canopy.
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Mar 23, 2006, 10:21 PM
Registered User
My TwinJet is stock twin speed 480s, 8xNiCd 2400s, flys great. One of the best planes I've ever bought. 75+ flights by now!
Mar 23, 2006, 11:29 PM
Rochester, NY
JustGoFly's Avatar
No doubt stock will work well for this plane. But I doubt it stock will perform with unlimited verticle and provide the speed I'm seeing with the twin brushless. I intend to push this well past stock performance. The one or two pushes to full throttle I did on the maiden made it leap like nothing I've experienced before. Well the MicroJet did react as well on the single motor and due to less drag should have a higher top end speed, but this big 2+ lb TwinJet is just so gorgeous and such a nice flyer. I doubt you could fly a MicroJet as slow. I am very impressed with this setup. I'll post a video after the weekend, if the weather breaks.

Mar 24, 2006, 08:18 AM
Vampyre Inc
HoverDown3K's Avatar
Very nice build and super clean looking, I like the battery tray for the lipos, seems like something those kits should come with.

Looking forward to seeing a video!!
Mar 24, 2006, 08:20 AM
Molded Hotliner Destroyer
Magnum9's Avatar
Vinnie, nice! Great minds think alike, I just did EXACTLY the same thing with the CF rod and tube for holding the rear of the canopy on my build last week. Not sure if you have seen the update of my second build, but I have a potential 850 watts at my disposal although radio interference is still my biggest problem.

Looking forward to seeing some video.
Mar 24, 2006, 09:42 AM
Registered User
I especially like your battery protection system Vinnie. That's a very elegant solution and could help to reduce damage to the nose section should the unthinkable happen.
Mar 24, 2006, 10:58 AM
Rochester, NY
JustGoFly's Avatar
Thanks guys. I think we all put a piece of ourselves in our planes, which makes crash's so painful. I tend not to decorate a plane until it's flown 10 times, but I have read many of the threads on the TJ and heard what a great flyer it is. I've also read that the drag of the airframe causes it to hit a wall and not be able to achieve high speed. This is why I chose the lower KV and larger prop 7x7 which has a calculated static speed of 101 mph. We'll see if we can brute force this puppy into 100+ mph.

Magnum - your thread was a must read. I'm setup for about 600 Watts and my limit is about 1 HP. It would be interesting to compare the results to see what thrust and speed we can each achieve. I'm betting it will take exponentially more power to achieve significantly more speed. I may try a 7x8 or 7x9 prop to see if it it worth the battery blistering power. All I can say is the speed I have with this plane right now is far from boring. Once I grow into using more than half throttle and occasional fast flybys, I'll go closer to the one horse, as you have done. Do you think the differential had any negative issues ? Sorry to see the crash and loss of LiPo's and plane. Your thread did inspire the Battery protection I made.

One test I did to see if I had > 1:1 thrust was to slow the plane down to a crawl then tip the nose up and just prior to stall, slowly increase the throttle. It was freaky watching the plane slowly climb, then increase in speed as it pointed straight up. Ya just gotta love high thrust setups. My single motor thrust is about 2 lb's (900 grams) and 101mph (163 Km/h) - each of which is less than yours but also the power drops to about 300 Watts for each motor, so this is suitable for my batteries. I can change props and achieve higher thrust and speed when I grow into it. But also change bells to convert the motor into a higher Kv motor and run smaller props. I am betting the larger props on lower Kv is right for this draggy plane.

Xxrando - bit your tongue ! I hope the inverse of what's happened to the MicroJet will occur on this plane I usually have to crash a plane a few times before I get the handle of it, so this one I hope to be very different.

HoverDown3K - thanks. I'm hoping Dojo will come out to the flying field. He has a very good eye for fast flying objects and does a nice job of capturing video. I may have to dial in 99% exponential to eliminate the shaking I'm doing while flying this beast

Last edited by JustGoFly; Mar 24, 2006 at 11:32 AM.
Mar 24, 2006, 09:22 PM
Registered User
Thrust to weight > 1.0, now that's gotta be a blast. Just gotta save up some cash to overhaul mine :-)
Mar 25, 2006, 01:15 AM
Rochester, NY
JustGoFly's Avatar

Second Flight

I must say WOW. This is a GREAT Plane ! I flew it again today, thrust was insane, I did only one fast flyby and am progressively wringing it out. It is just so easy to fly. I landed her hot since I hadn't tried to see how slow it could fly. So the first 4 minute flight was fairly fast and landed at about 1/4 throttle and slid for about 15 feet. Next flight I brought it up high and backed the throttle down to about 20%. She justt crawled across the sky. I backed it down more and did high alpha a couple miles an hour and extremely stable. Sheesh - I wonder why I landed so quickly on the last flight. This plane can go slow and fast ! Climbs were insane and could only do about 5 seconds before I'd kill throttle.

ONE PROBLEM: On the straight up climb I had to hold the elevator all the way down to keep her from coming around on her back. I also have the trim set down and when I am flying level and hit the throttle - the plane will climb. So my angle of the motor mounts is off. I broke them out tonight and reglued with them being 90 degrees to the rear of the plane. I'm hoping this will make the plane fly true.

Video was captured, but more flying tomorrow and I gotta catch some shut eye.

Mar 26, 2006, 10:47 AM
Registered User

I am one of your 450TH fans that I have installed on my STRYKER and have to say your products are AWSOME! The work on this TJ is outstanding, I just have to wonder what the plane will do when you convert to the higher KV bells with smaller props???? Speeds should be blistering fast waaaaay over 100mph dont ya think?

Im 98 mph level flight with my Stryker running 4 cell on a 4.1x4.1 apc E prop. dont know if installing a 5x5 would help or hurt me, but if you run the high kv bell your plane should annihalate my bird. not to mention the fact i think your TJ has a better aerodynamic airfoil from what i have been told. cant wait to see your next project... hey maybe a STRYKER hint hint, i will say that those MEGA powered guys dont think your motor can compare.....
maybe its time you showed them what that 450TH is all about.. heehee
just a though
your loyal motor flyer
Mar 26, 2006, 09:20 PM
Rochester, NY
JustGoFly's Avatar
PZK - Thanks for the kind words - lots of guys have found the 450TH and Mega's are pulled as paper weights I put a 450TH on my MicroJet and it was an Este's rocket. Unbelievably fast. I didn't want to make that same mistake. Most of the problem was due to my using cheap extension cables I bought used, but crashed the MJ three times. I do not want to do that to the TwinJet. The speed this plane flys is scarey and until I get used to it, I won't try the higher speed 450TH. I have it setup so I can just swap the bells, exchange two of the wires going to the ESC and I'm on the higher speed motor. The two bells with props sit in my flight case. But the 450T on 7x7 is just soooo fun and I'm finding that I am not leaning on the throttle too much. I'm editing some video right now. So I hope to post the Video of todays TwinJet flying soon.

after the ESTE's launch of the MJ and the 450TH, I backed down on the throttle and here is a video of it's demise:
MicroJet - 6x4 prop - setup for 100 mph max down from 5.5x6.5 prop Glitching in one elevon and serious nose down pull led to a very short flight.

The guys at the field see the big 2 1/2 pound TwinJet come out and after they saw me tip the nose up and climb they just started laughing. 5 seconds is enough time for it to disappear into the clouds. I had alot of fun playing escort for a buddies 4 motor warbird. I could close the distance between his plane and my jet within a few seconds from anywhere on the field. Man this is just too much fun !

Mega ain't got nothing on the 450TH. I have whole flying clubs pulling the mega and putting in the lighter and faster 450TH. In addition to the speed it's more versatile since you can swap the bell and run larger props like my 450T - 7x7 prop. Swap the bells again and fly in a helicopter or geared in a large airplane. I was 3D'ing my 6 foot wingspan A.P. plane today - 3 lbs.

Mar 26, 2006, 10:08 PM
Begin with end in mind...
power's Avatar
Originally Posted by Magnum9
Vinnie, nice! Great minds think alike, I just did EXACTLY the same thing with the CF rod and tube for holding the rear of the canopy on my build last week. Not sure if you have seen the update of my second build, but I have a potential 850 watts at my disposal although radio interference is still my biggest problem.

Looking forward to seeing some video.

Just a thought on your interference, carbon to carbon chaffing can be a source of RF noise, this is exactly what you "could" have with your canopy hold down. It could be a problem if it is loose at all or is allowed to vibrate. A nylon tube would work just as well.

Mar 26, 2006, 11:37 PM
Rochester, NY
JustGoFly's Avatar

Thanks for the info. I do know about the CF potential to wreck a day, since I have built a purely CF airplane and fly it daily. The crash video was of the MicroJet - not the TwinJet. The MJ is smaller and has only a CF arrow through the underbelly. The glitching seems to be my poor selection of old extension wires going to the servo's. I'll have to double check your suggestion though to make sure those wires and the antenna don't come near any CF.

On the TwinJet the canopy CF rod and CF tube are completely covered by EPP, and the antenna doesn't come near it. If I were do do it again, I'd probably use a dowel and a plastic tube. The tubes that come in CD/DVD spindles would work very well.

The TwinJet is still very healthy and flying great ! I will post a video of my second and third flights with it. It is a very exciting plane and the throttle is directly hooked to adrenaline ! I'm using an Electron 6 dual conversion receiver and it is working flawlessly.

Mar 27, 2006, 06:18 AM
Molded Hotliner Destroyer
Magnum9's Avatar
Vinnie, I think the reply on the CF was directed at me, and yes I do have bare CF rod running inside bare CF tube for my canopy hold down. I would love other suggestions though. The antenna is running parallel to the CF LE about 1.25" away for a length of 10". Also the servo and ESC leads running to the Rx are basically bundled side by side for around 3" and I have ferrite rings on the ESC leads. The main battery power leads are running past the Rx within 1.5", maybe a rush of 80+ amps through these is generating a massive RF spike. I am to scared to fly this again until I sort it out and range test it properly on the ground first. I have too much time and money invested in it now to treat it as one of my usual "foamies".
Mar 27, 2006, 02:40 PM
Registered User
just checked out the MJ video you posted and that bird was movin pretty good till the end, it hurt to watch that . what amps were you pulling on the MJ with the 6x5.5 prop? here is why i ask
I am running the 450TH like i said in my stryker on 4 cells on a 4.1x4.1 prop pulling 28 amps and level flight speeds of 98 mph, with the 4.75x4.75 im pulling 32 amps and 100+ mph level flight , when i tried the 6.5x4 prop i pulled 46 amps!!! on 4cells
so on 3cells same prop,amps should drop alot shouldnt they? see i tried 3 cells with the 4inch props and speeds were around 65 70 maybe. thats why i have been running 4 cells. what do you recommend?

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