Projeti on Steroids - ARC 28-47-1.5 Turn BL Inrunner - Page 2 - RC Groups
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This thread is privately moderated by ChrisWNY, who may elect to delete unwanted replies.
Nov 27, 2007, 07:15 PM
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Nov 28, 2007, 10:41 PM
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I use 20/30C 3s 2300packs all summer in a 600watt MicroDan powered Projettti and static they pull 56 amps with the Thunderbird 54 ESC, using an APC 4.1X4.1. holding 3.41 VDC per cell, once we lowered the motor by 3/8" 2/3 throttle hand launches are a cake walk. Thus why I'm convinced this airframe can easily carry more weight.

For first flights IMHO its best to prop down to lower pitch props for low end torq for hand launching ease versus starting with your extreme speed pitch props.

Once I figure out where the ARC 28-47-1.25 motor lives I'll send it off to MicroDan to figure out a sub 40 gram outrunner to equal its performance.
Latest blog entry: Cappys new Carden Hauler
Nov 29, 2007, 07:38 AM
Gone Flying.
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c/f -

Thanks for the suggestions - how about starting with a larger prop with lower pitch? Instead of 4.75x4.75, how about a 5.5x4.3 CAM speed? I know the larger prop would give more low-end thrust, which would aide those hand launches. If the prop doesn't give me enough thrust from the get-go, that Projeti is going straight into the ground in a blink...
Dec 03, 2007, 08:27 PM
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Motor Mount - c/f Arrow Shaft and Kevlar Thread

It may not look like much Kevlar thread was used, but I actually went through an entire spool of the stuff wrapping the motor mount and arrow shaft to ensure a strong and (literally) bullet-proof bond. I filled the voids full of epoxy where the corners of the inside of the mount (designed for a square 10mm stick mount) go around the round 10mm carbon fiber arrow shaft for a solid bond. The mount felt incredibly strong even though the epoxy had still not cured, once the Kevlar thread wrapping was complete, it felt like the mount could withstand hundreds of pounds of pressure.

After wrapping the mount and shaft (shown in the photos) with Kevlar thread, I coated the thread with epoxy to seal things off and form the strongest bond possible. You have to be careful with Kevlar thread, even an insane amount of tension will not break this stuff, it'll slice your finger way before it would have any chance of breaking. You start off by tying a knot, then wrapping the Kevlar thread around the mount and arrow shaft as tightly as possible until it feels very secure. Once the epoxy cures, it's permanent. No chance of the mount coming off, even in the most brutal crash.

For anyone else trying this, I'd recommend wrapping more thread around the rear of the mount, where there is that transition between the mount and the c/f arrow shaft. However, it doesn't take much Kevlar thread to ensure a solid structure once you add epoxy. I avoided creating a "lump" of thread anywhere on near mount surface, since it would cause issues with screw hole alignment when aligning the ARC 28-47-1.5 inrunner to the slots in the aluminum mount. There is some room for play, but not much.

Kevlar thread is available from for about $1.95 per 10 yd. spool. It is great for tying bass bugs and other applications that require very strong thread. I purchased the red aluminum light-weight motor mount, which can be used with an inrunner OR outrunner, from

I will start off by trying to mount the motor INVERTED, but will not epoxy anything until I determine whether or not it will work. An outrunner would be ideal for an inverted mount, since I could butt the mount right up against the tail. However, an inrunner must go between the mount and the tail, meaning I'd have to place that motor further back, which could really cause problems with c/g balancing, especially on 3S. Ideally, I'd like the motor to end up low on the airframe considering the high-speed potential of this Projeti...
Last edited by ChrisWNY; Dec 03, 2007 at 08:58 PM.
Dec 12, 2007, 04:34 AM
mkmkmk13's Avatar
can u hear me??
lol j/k
what happend man??
please update
Dec 12, 2007, 07:23 AM
Gone Flying.
ChrisWNY's Avatar
I've been in a "Projeti lull" the past week due to a lot of things going on - will be mounting the motor on the Projeti fuse shortly, hopefully by the end of the week. The weather has been awful up in my area lately - windy, cold, snow/rain, just not good for flying, so I've been pacing myself and watching the weather forecast closely to find out if I'll have a good day for a potential maiden.

I'll take more photos once the motor is on, and I've achieved a feasible c/g balance on 3S-5S. Bear with me!
Last edited by ChrisWNY; Dec 12, 2007 at 07:38 AM.
Dec 20, 2007, 09:10 PM
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Motor Positioning - Need Opinions

I cut the c/f arrow shaft down to size so that I could begin positioning the motor on the rear of the Projeti. I'm wondering if anyone has suggestions regarding the motor placement - I'm thinking it might be better off down low, for more than just cosmetic reasons.

If I flip it up, I'll be able to move the motor more toward the center of the plane, meaning that c/g balancing will be easier. I'm not sure if it will be possible to c/g balance the plane if the motor is placed where I have it currently, as shown in the photos. Yes, I haven't even set the batteries in the front yet to test out c/g.

I suppose I could cut a notch in the upper part of the tail to bring the motor in a bit further, up until the point where the prop would shred the airframe. What do you guys think?
Last edited by ChrisWNY; Dec 20, 2007 at 09:17 PM.
Dec 23, 2007, 11:59 PM
zoom zoom
gotboostedvr6's Avatar
did this fly yet?

good info
Jan 15, 2008, 04:50 AM
zoom zoom
gotboostedvr6's Avatar
bump fly yet?
Jan 15, 2008, 07:36 AM
Gone Flying.
ChrisWNY's Avatar
Not yet - I have been caught up in the home stretch of my new house that is being built, so the Projeti has been shelfed temporarily. I will definitely be getting back to it soon though, so keep checking...
Jan 17, 2008, 04:32 PM
Registered User

I tested the arc 1.5 on 5S 2500 mah EVO (rated for 25C) and you are right, It takes 64 amps static.

EVO 25 is rated for 62 amps continuous even so LVC kicks in after 15 seconds or so. Its brand new EVO cycled 3 times.

My next step is to cut and balance a 5.2 X 5.2 graupner to 4.2 X 5.2 and check the amps. I would like my static amps to be around 55 so that I could get at least 2-3 minutes of WOT flight from the pack.

Will keep you posted...
Jan 17, 2008, 08:17 PM
Gone Flying.
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Thumb - yep, your numbers are right on. I might have to prop down (at least in pitch) to lower my amp draw before I try a maiden. Keep me posted on how those other props turn out...
Feb 19, 2008, 06:06 PM
Registered User

The arc motor is off my funjet and trial fitted on the Projeti now.

If it doesn't rain this weekend then I will get a chance to test fly it. On the funjet the prop didn't bite well as I expected but it flew incredibly well at 154 mph. My funjet build thread has eagletree graphs (2000 + watts ). That is close to 3 HP.

I'm going to go with a 4.7 X 4.25 APC prop initially to keep the amps under 60 on the projeti but later planning to cut a graupner 4.7 X 4.7 small enough to stay under 60 amps.

How is your Projeti coming up?
Feb 20, 2008, 07:50 AM
Gone Flying.
ChrisWNY's Avatar
Thumb -

Projeti is still on the table, just haven't mounted that motor yet. It will definitely be ready by Spring, although a Winter maiden is not out of the question, especially considering the "natural cooling" I would have available.

I was out flying my "upgraded" FunJet this past weekend (in 20F temps with snow) with the new ARC 28-37-2.5 on a 5.5x4.3 Graupner CAM speed prop, wow does it haul. EagleTree airspeed readings topped out at 108mph in a slight tail wind. Very good speed on 3S at ~35 Amps. Expect even better results with 4S.

Here are photos of my FunJet in action from this past weekend. You can clearly see the Graupner spinner w/prop on the back. The strapping tape on the bottom keeps the fuse in good shape on those long landing skids. Landing was a lot of fun this weekend, the FJ would skid 20-30 feet on the snow before coming to a stop, as shown in the second photo.
Last edited by ChrisWNY; Feb 20, 2008 at 10:44 AM.
Mar 06, 2008, 09:22 PM
Fly it like you stole it..
Tram's Avatar
Can't wait to see your ProJeti..


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