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Hobbico NexStar ARF to electric - 10/28/2009 8:54 PM   
Waterlogged


 

Posts: 206
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Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		This plane is easy to work on and cut weight in a few key places. Given a decent budget to buy the good stuff, and some research on what not to do.... I have started the project .

Here are the mods:

1st- Nose from firewall forward shaved. Make a 2.5" CF tube and set thrust angles the same, adjust the heigth of the tube to allow more prop clearance. Maintain the stock landing gear (cut off the top portion of the metal motor mount to act as the top brace for the front landing strut) and cut cooling holes in the firewall. CF tube has 8 "fingers" that protrude through the firewall and epoxied in place, with FG cloth on the front of firewall for cooling tube and landing gear mounting strength.

*The weight of the CF tube/motor face plate/FG firewall layer weigh 1.85 ounces........ the stock nose forward portion that was removed weighd 2.15oz... (Weight savings of .3 ounces.. NOT much but I raised the prop clearance 1.25 inches and made a better cooling solution, well that, and it'll be a tad bit stronger).

** This tube enables a Plettenberg Orbit 25-16 Outrunner and Pheonix ICE 75 ESC/BEC mounted inside to have a constant forced airflow**

2nd- Now a new cowl is needed... I used some scrap white foam and made a foam block which I then sanded to shape and layered 2x FG cloth and epoxy resin, it's curring. Hopefully I'll be able to make a plug out of it and be able to vacuum bag as many copies as I need.

I'll update later today.

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< Message edited by Waterlogged -- 10/28/2009 10:41 PM >

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RE: Hobbico NexStar ARF to electric - 10/30/2009 7:50 PM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Grrr.... the 4th coat (FINAL) of white epoxy caused the others to lift, it's all a curdled mess. I'll have to scrape off and wait a week for a full cure, then sand. At least the next run will have a smoother result, since I'll know where the "trouble" areas are, humm... maybe that's a good thing. =)

Off to start the wings!

-WL

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RE: Hobbico NexStar ARF to electric - 10/31/2009 4:38 AM   
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Posts: 206
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Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Installed the 88oz digital servos in the wings, great fit and in fact, Hobbico even had the string there for me to pull my extension through.

I weighed the flemsy center joiner, I think it's made of Nylon... and the 14inch long steel joining rod= 5.85 ounces. I think I can fix this, lighten it up, get rid of the dihedral and strengthen the whole wing at the same time.

There was already a "Box" for a square wooden joiner @0.25" x 1.25" x 6.5" in each wing, just had to cut the slot for it through the 3 ribs in each wing half.

Next: Made a 12"x1.25" (Almost the same size as the school 1-foot ruler) out of 1/8th inch ply and a matching 2mm thick CF ( I think it's 5-lam CF/epoxy board.... it came in a 12"x9" sheet @$30 from one of the helicopter parts shop here in town). The CF/Ply joiner is clamped down for an hour to let the 15min epoxy cure.

Once the wing has cured, I'll lay a 2" strip of FG around the joint.

-WL

< Message edited by Waterlogged -- 10/31/2009 7:00 AM >

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RE: Hobbico NexStar ARF to electric - 10/31/2009 5:05 AM   
snuts


 

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Last Login: 2/3/2012
From: camrose alberta, AB, CANADA
Status: online 		Your doing good.Sometimes it's nice to know someone is following. Maybe add a photo of your cooling air exit at some time.
-Snuts-

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RE: Hobbico NexStar ARF to electric - 10/31/2009 6:49 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		I'll probably be cutting the cooling air exit last =)

The wing has been joined and is curing. CF/Ply joiner weighed less than the Nylon center joiner..... and I didn't have to use the heavy steel rod =).... Wing's flat and stronger, while @4oz lighter. I should have gotten pictures of the wing joiner and the slot cut in the ribs...... but I WAS ON A ROLL! Anyway, you can't help but find it easy to do since the box is already there, just hidden.

I'm not going to touch the work bench for a full 24hrs while the wing is there.

Once dry, I'll install the forward pin (hardwood dowel) and glass the center section, then drill the rear wing bolt hole to complete the wing.

Next: Install the tail, radio gear and Motor/ESC, then assemble the plane and find the C.G. so I know where the 6S A123 cell pack needs to go.

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< Message edited by Waterlogged -- 10/31/2009 7:11 AM >

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RE: Hobbico NexStar ARF to electric - 10/31/2009 11:46 AM   
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Posts: 206
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Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Cousmetically speaking, the cowl isn't pretty but very light and fits. Once it's fully cured, say 4-5 days.... I'll open up the nose on it and align it to the motor/nosecone.

I just glassed the center section of the wing and will drill a hole for the front pin tomorrow. It looks nice and straight. Hobbico does a nice build job, everything is good quality.

-WL

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RE: Hobbico NexStar ARF to electric - 11/1/2009 12:21 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		2" long carbon .20" dowel in place and threaded with CF thread in a X pattern.

Assembled but still need to install Elev/Rudd, Rx and ESC.............. then it's time to work on the battery placement (w/front windshield as battery box access hatch), woot woot. Just a few minor things like covering the center of the wing and matching the color scheme on the cowl.

WL

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< Message edited by Waterlogged -- 11/1/2009 10:22 AM >

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RE: Hobbico NexStar ARF to electric - 11/7/2009 5:25 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Plane completed @112oz= 7lbs. I have run 6 WOT runs on the bench (Static).... A123 6S

1st- APC 12X8E 29A 520W 2100mA out of pack (110F Battery) (85F ESC)(112F Motor)
2nd- APC 12X8E 29A 520W 2100mA out of pack (112F Battery) (84F ESC)(113F Motor)
3rd- CAM 14.5X9.5 folding 44A 880W 2150mA out of pack (140F Battery)(145F ESC)(200F Motor) Too Hot! with current cowl opening...... Clearance is only 1/2 inch =/
4th- CAM 14.5X9.5 folding 44A 870W 2150mA out of pack (120F Battery) (88F ESC)(120F Motor) Opened cowl and added 2 cooling ducts...... Clearance is only 1/2 inch =/
5th- Zinger 14X8 wood 42A 790W 2100mA out of pack (113F Battery) (84F ESC)(116F Motor)
6th- APC 12X8E 29A 525W 2100mA out of pack (87F Battery) (83F ESC) (106F Motor) improved cooling!

Think I'll find an APC 13X9E for @37A with 1inch clearance..

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RE: Hobbico NexStar ARF to electric - 11/7/2009 10:35 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		CG set and ready to fly. -WL

106oz 6s A123 2300mA APC 14x8.5E 7850rpm 106oz thrust 49A 16.1V = 790W
* single 6s has a greater voltage drop at 16.1V

124oz 6s x 2 A123 2300mA APC 14x8.5E 8300rpm 118oz thrust 53A 17.9V = 950W
*2 x 6s1p see only 26.5A each therefore the lower voltage drop at 17.9V
= higher %efficiency.



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< Message edited by Waterlogged -- 11/16/2009 1:26 AM >

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RE: Hobbico NexStar ARF to electric - 11/16/2009 11:42 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		RTF at 106oz is great!
This Plettenberg Orbit 25-16 can run up to 7s and 50A....1300 watts 85%eff

I could switch to a CF foam core wing (Clark-Y airfoil) and a 7s1p2300 LiPoly and drop the weight another pound for @90oz at 1100W for a 195W/pound ratio. (159oz thrust)

-WL

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RE: Hobbico NexStar ARF to electric - 11/26/2009 4:41 AM   
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Posts: 206
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Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Got in the first 6 flights today. Not a single problem other than the flying baby spiders I kept running into, they loved crawling on my face while I was airborne.

A123 6s 2300mAh packs........ with 5A/6V BEC running..

Flight
#1= 5 minutes to trim the plane......1044mAh out of the battery

#2= 8 minutes........... 1470mAh out
#3= 9 minutes........... 1781mAh out
#4= 11 minutes........... 1930mAh out
#5= 11 minutes........... 1913mAh out
#6= 12 minutes........... 2007mAh out

90% of time @60% throttle
Max 780W 44A

-WL

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RE: Hobbico NexStar ARF to electric - 12/27/2009 7:07 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		27 Flights sofar, only thing needing to be tightened was the lower Nylon front landing gear strut brace.

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RE: Hobbico NexStar ARF to electric - 1/28/2010 2:13 PM   
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Posts: 206
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Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		This power system runs like a 5S 3200mA Lipo setup.

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RE: Hobbico NexStar ARF to electric - 2/1/2010 7:35 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Today I set up the Cg for a 6S 2200mA Lipo pack and timed the Castle Creations Pheonix ICE-75 for Normal Timing and kept the APC 14x8.5E prop.....

Motor pulls 70A @1610 watts for fast verticles and throttles down for 25 minute @30% throttle for sunday flying. All on a 2200mA pack.

I really like this set up as the plane takes off like a rocket! I flew the A123 cells and it wasn't the same =/ but the A123 cells charge in under 10 minutes where the Lipos are double that. The A123's seem to be the best for sport use.

There are 36 flights sofar on the model.

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RE: Hobbico NexStar ARF to electric - 2/4/2010 12:48 PM   
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Posts: 206
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Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		I ordered 2 more A123 cells to turn my packs into a 7s A123 2300mA packs. They weigh 20 oz each now, this makes the NexStar 110 ounces.

With an APC 14x8.5E on 7s-A123 it's right at 1250W/65A straight up at full throttle. @180W/lb. This is a great model, a real treat to fly. It cruises for 25 minutes @30% throttle on 2300mA.

The batteries are charged way before I need to land the plane. I did 8 flights in a row with only taking a minute or so to land and swap packs on the charger/model. I use a Hyperion EOS 720i Net 3 7S 20A 250watt Balancing Charger at 10Amps

I love A123!!!!!!

-WL

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RE: Hobbico NexStar ARF to electric - 2/26/2010 2:48 AM   
FightingGravity


 

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From: Simi Valley, CA, USA
Status: offline 		Nice Job Waterlogged, both the conversion and the write up.
Looking to do something similar this summer.

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RE: Hobbico NexStar ARF to electric - 3/24/2010 1:49 PM   
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Posts: 206
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From: Eugene, OR, USA
Status: offline 		I found out today that my huge deep cycle battery is good for only 12 charges of a 7sA123 2300 pack =/

12 x marathon of 15 minute flights landing only to swap packs on the charger........ 3 solid hours of relaxing 40% throttle.

LOL, I need another matching Trojan deep cycle battery and run them in 24v series. The 720i charger loves 24 volts!

Sofar 60 flights and about to stop counting. The batteries continue to take in 2230mA....... still act new. I love A123's and this motor!

-WL

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RE: Hobbico NexStar ARF to electric - 3/25/2010 11:24 PM   
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Posts: 206
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Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		GPS shows WOT of 78.0 mph in level flight on 7sA123 2300's and an APC 14x8.5E setup.


< Message edited by Waterlogged -- 3/28/2010 9:48 AM >

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RE: Hobbico NexStar ARF to electric - 6/1/2010 10:06 AM   
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Posts: 206
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Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Okay OK, I'm done counting at 80 flights. The 7sA123's continue to run like new, the plane still flies like new, the motor is smooth and never needs oil in the bearrings. It's a great model and has never touched a wingtip on landing.


-WL/DSD

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RE: Hobbico NexStar ARF to electric - 6/2/2010 4:10 AM   
FightingGravity


 

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From: Simi Valley, CA, USA
Status: offline 		Would you have made any improvements or changes now that you have logged plenty of flights?

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RE: Hobbico NexStar ARF to electric - 6/2/2010 4:49 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		The stock wing mounting system works perfectly fine. My nylon wing bolt nut is cracked but it's been fine the past 50 flights after I noticed it (the rubber sleeve around the nut holds it really tight and snug against the threads). I'm still using the original wing bolt at 80+ flights and should replace it......... But the ARF kit materials have been flawless.

I would like to have ordered a Clark-Y foam core wing and glassed it to save about 10 ounces over the stock nitro ARF NexStar wing. If you have foam core wing building experience you can get them from this link below. I made the ARF wing flat, no dihedral and the plane tracks extreamly well.

http://www.flyingfoam.com/CustomMain.html

I also used regular 1.6oz digital servos that came with my D7 Spectrum radio. A person could use (4) 1oz HS-225MG servos and be just fine.

With a new lighter wing and servos the plane would have better inverted flight charactoristics and weigh @93-94 oz. @215w/lb

The plane is a rocket at 106oz as is now, so why complain? I'm so happy with this setup! Like I have said..... I'm still in the air when the first 7sA123 is done charging. I use the 720i Net3 charger from Hyperion which charges at 250watts (7s balancing and 10A charging).

This is a trainer and slow flights of 20+ minutes can be boring, but you can go vertical any time you want. I still get a kick out of coming in for a slow landing and throttle up into vertical until 500 feet. It's like cheating.

I will post a few videos the next time I go out to the field. I'll have someone else fly it as I tape LOL. Cross your fingers.

-WL

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RE: Hobbico NexStar ARF to electric - 6/2/2010 5:10 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		From the data, this plane only needs @125W to maintain level flight with a small amount of climb, @5 degrees climb. If a person used a 4s Lipo pack and a 500W motor it would work just fine.

I just happened to build it with the ability of 1600W on a 6s Lipo pack, but I use 7sA123 2300mA packs because they DON'T CATCH ON FIRE

-WL

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RE: Hobbico NexStar ARF to electric - 6/2/2010 5:18 AM   
FightingGravity


 

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Status: offline
quote:

ORIGINAL: Waterlogged


I will post a few videos the next time I go out to the field. I'll have someone else fly it as I tape LOL. Cross your fingers.

-WL

Very Cool, can't wait to see it.

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RE: Hobbico NexStar ARF to electric - 6/7/2010 1:20 AM   
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Posts: 206
Score: 100
Joined: 10/2/2006
Last Login: 10/18/2011
From: Eugene, OR, USA
Status: offline 		Here are some of the logs. Now that I have a way to show them.

Longest level flight 7sA123 2300 apc 14x8.5E low timing... Plane only needs @85w to fly well =)

and

Last 6 flights.... Playing around shows power @450-600w for fast sport flying and manuvers =)


Each spike @1100watts is going full throttle after a slow flyby @30 into the 90 degree vertical pull out and up to 500 feet. Takes about 6 seconds to climb =)

-WL

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