HobbyKing.com New Products Flash Sale
Closed Thread
Thread Tools
Old Oct 10, 2008, 04:02 PM
Registered User
GryphonRCU's Avatar
United States, CA, SF
Joined Mar 2008
3,848 Posts
xyz-2-xyz,

Folks who have ran that motor can better answer you than me.


Meanwhile assuming you mean the 28-47-1.5 2800KV motor:

You didn't mention your ESC specs.

From what you listed in your last post, the 3S-2500 is going to be your limit.

Prop with regards to its practical amp limits and its temp...motor will have a real easy time of it because it will not be anywhere near its max power.

_______________

You can run (2) of your packs in parallel to stay at 3S voltage but double capacity and AMP rating. "C" rating will stay the same but it will become 3S-5000 and you should be able to distribute the weight well because of two packs.

You can then flow more amps and fly faster and have longer duration flights at cost to low speed handling capabilities due to increased weight.

Parallel connection is positive to positive, then negative to negative. You can make an adapter or buy the small adapter for $8 or less (Great Planes makes one for Deans Ultra plug connector).

Then you really do need to mention your ESC specs to see which one of the main 3 items is your bottle neck: Motor, ESC, or Battery.
{Assuming 20C packs then the twin parallel packs will NOT be your limiting factor}

_______________

*********
*********
With comment on your ESC specs and your desire to run parallel packs (or not), the folks who have run that motor can best advise you.

Here is a thread with lots of info on ARC motors:
http://www.rcgroups.com/forums/showt...630759&page=43

I think Thekid3418 is one of several guys who tested that motor with healthy AMPs.
Don't skimp on full size 28mm heat sink, or put it off...$4-$6


Gryphon
GryphonRCU is offline Find More Posts by GryphonRCU
Last edited by GryphonRCU; Oct 10, 2008 at 05:13 PM.
Sign up now
to remove ads between posts
Old Oct 10, 2008, 08:47 PM
So Cal FPV Aviator
EyeFlyPlanes's Avatar
USA, CA, Santa Clarita
Joined Feb 2008
3,575 Posts
Does anyone know of a better simulator for the funjet other than the crappy one from multipex? I try to trim it out and it is impossible to fly level, it will always roll left or right through the whole flight. I'm just looking for another simulator that will not be too expensive. I need a funjet or something like it to fly.
EyeFlyPlanes is offline Find More Posts by EyeFlyPlanes
Old Oct 11, 2008, 01:37 AM
Registered User
California
Joined Mar 2008
262 Posts
quick question will the 28-47-2 put me past the 100mph quota on 3s 2500 25 c batt? and to answer the esc i run is the thunderbird 54 but will be changing to the suppo 100 soon so i can run 4s. i want to get an arc motor for my funjet whats better fo speed an thrust 2win or 1.5 what props an will it be versitle when changing to 4s
xyz-2-xyz is offline Find More Posts by xyz-2-xyz
Old Oct 11, 2008, 04:15 AM
So Cal FPV Aviator
EyeFlyPlanes's Avatar
USA, CA, Santa Clarita
Joined Feb 2008
3,575 Posts
Quote:
Originally Posted by xyz-2-xyz
quick question will the 28-47-2 put me past the 100mph quota on 3s 2500 25 c batt? and to answer the esc i run is the thunderbird 54 but will be changing to the suppo 100 soon so i can run 4s. i want to get an arc motor for my funjet whats better fo speed an thrust 2win or 1.5 what props an will it be versitle when changing to 4s
Ya man ive got the arc 28-47-2 and this thing is insanely fast on a 4 cell with either a 5x5 or 5.1x4.5 apc prop. If you want a nice stady climb where it will glide out of your hand then go with a 6x4. Ive got the turnigy plush 60a esc and ts plenty for me. I've got the rhino 4 cell 2350 25c lipo. What a fantastic battery. U need a battery like this to get the right cg for that 110g motor.
but for the price, that motor is insanely powerful and very efficient.
EyeFlyPlanes is offline Find More Posts by EyeFlyPlanes
Old Oct 11, 2008, 05:25 PM
Registered User
GryphonRCU's Avatar
United States, CA, SF
Joined Mar 2008
3,848 Posts
xyz-2-xyz,

My simulation shows that you can fly at 100 MPH with your 3S-2500 25C, ARC 28-47-2 2170 and your CC 54A ESC if you run 6.5X6.5 prop.
None of the above 3 items will be getting pushed hard.
(Might be in the 40-45A range) Don't forget to mount the motor heat sink.

Should have a slight speed advantage along with MUCH better vertical climbing (unlimited) compared to the 4S in the previous post which might be running under 30A w/ 5X5 prop.


Graupner 6.5X6.5
If you buy one w/large 8mm bore it might need adapter. I use adapters that come with APC 6" or smaller E props. Might be available in 4.8mm and 6mm…not sure ask stores over the phone.

APC Pylon 6.5X6.5 (Competition)
They work great for my friends and I and are very heavy duty. Great for high powered electrics.

http://www.newcreations-rc.com/Produ...e=G&catlevel=2
GryphonRCU is offline Find More Posts by GryphonRCU
Old Oct 12, 2008, 10:08 PM
The Kid
Thekid3418's Avatar
Detroit, MI
Joined Dec 2007
2,586 Posts
IMO you'd probably have to go 4s to get to 100 on the 28-47-2. Run that with a 6x4 or a 6x5.5 and you should be good. And it'll draw about 45 amps. The 28-47-1.5 is a monster, everyone knows that. Unfortunately i ruined mine before i really got to push it. But that on 3s with a 6x4 would be a good combo. Or a 5.5x5.5 maybe.

The 28-47-1.5 is pretty versatile for going to 4s. You'll be around 60 amps with a 4.75x4.75 and you'll be up to 70 amps with a 6x4 (which is a known 150 mph setup on some flying wings). The 28-47-2 is an amazing motor. It could come close to 100 on 3s, could easily touch it on 4s, and could go far and beyond it on 5s. I ran mine in a pylon plane on 5s with a 6x5.5 and it probably went around 140. Thats about 65 amps and 1200 watts. And the motor would usually come down warm as long as you watched your throttle use. You could run it on 6s with a 6x4, which again draws mid-60s on amps at 32k rpm. That would be a MONSTER funjet!!!!

Unfortunately, my 28-47-2 has been religated to 3s duty because i think i may have damaged it. I ran it for about 40 seconds straight at 1250 watts and it got a little too hot i think. So thats a good idea as to your limits of that motor...

Hope that helps
Thekid3418 is offline Find More Posts by Thekid3418
Old Oct 12, 2008, 11:13 PM
So Cal FPV Aviator
EyeFlyPlanes's Avatar
USA, CA, Santa Clarita
Joined Feb 2008
3,575 Posts
Better simulators for the funjet anyone?
EyeFlyPlanes is offline Find More Posts by EyeFlyPlanes
Old Oct 13, 2008, 02:35 AM
Registered User
Joined Oct 2008
490 Posts
Good point.

In case anyone is interested Im using a Six Series 2700kv motor with a 2200mah 3S pack.
With a 6 X 5.5 APC prop Im drawing 42A (on the motors limit) at WOT.
Johannesburg is 5750 feet above sea level. A 6 X 4 prop draws the same current at sea level.
Im concerned that I will burn the motor out - can anyone tell me what the surface temperature limit of the motor will be ?



Quote:
Originally Posted by Aio_1
You're going to get tip vortices either way.
There's more wetted area with the tanks but I'm not sure how they effect the induced drag. I'd expect a small reduction in drag by removing them but surely that's not what this plane is about?

If you want a low drag airframe don't start with a Funjet. For me the idea of hacking off bits that are part of the character of the plane poses the question "why didn't you just buy an airframe designed to go fast instead." I'd chop off the tanks if I preferred the plane without them but I don't think I'd do it just for a small speed increase.

Aidan
War Machine is offline Find More Posts by War Machine
Old Oct 13, 2008, 04:28 AM
RC pilot by soul
Israel
Joined Apr 2005
2,494 Posts
Guys,

Just to add some more to the talk - im using a Medusa Research 028-040-2200V2 motor in my Funjet with a Graupner 6x5.5 making about 1KW (!!) at WOT on a fresh pack.

Needless to say. it is fast ! the same funjet was dopplered coming out of a dive at 131Mph with weaker batteries making onlt 700W, i wonder how fast it is now.
i3dm is offline Find More Posts by i3dm
Old Oct 13, 2008, 06:36 AM
Registered User
Joined Oct 2008
490 Posts
Nice fugures ! What pack are you using ?
What current you drawing ?

BTW - how is speed measured using doppler ?
War Machine is offline Find More Posts by War Machine
Last edited by War Machine; Oct 13, 2008 at 06:49 AM.
Old Oct 13, 2008, 07:37 AM
RC pilot by soul
Israel
Joined Apr 2005
2,494 Posts
im using a 4S 2100Mah 25C and 3700 Mah 25C. it was at about 65-68A.
and YES the little medusa can take it (MR heatsink installed) with no problem.
i3dm is offline Find More Posts by i3dm
Old Oct 13, 2008, 07:40 AM
Checking CG is for NERDS!
Smokescreen38's Avatar
Joined Jun 2005
5,347 Posts
Quote:
Originally Posted by Aio_1
You're going to get tip vortices either way.
There's more wetted area with the tanks but I'm not sure how they effect the induced drag. I'd expect a small reduction in drag by removing them but surely that's not what this plane is about?

If you want a low drag airframe don't start with a Funjet. For me the idea of hacking off bits that are part of the character of the plane poses the question "why didn't you just buy an airframe designed to go fast instead." I'd chop off the tanks if I preferred the plane without them but I don't think I'd do it just for a small speed increase.

Aidan
I think you make a good point... but it looks to me like most people did buy this plane because you can make it rip...

What would have been a better choice for a high speed foamy of this size and quality?
Smokescreen38 is offline Find More Posts by Smokescreen38
Old Oct 13, 2008, 08:32 AM
Registered User
Joined Oct 2008
490 Posts
Im suprised the motor can take it - its rated at 40A maximum.
My 6-series 2700kv is rated at 42A - I wonder how far I can push it ?

Quote:
Originally Posted by i3dm
im using a 4S 2100Mah 25C and 3700 Mah 25C. it was at about 65-68A.
and YES the little medusa can take it (MR heatsink installed) with no problem.
War Machine is offline Find More Posts by War Machine
Old Oct 13, 2008, 10:07 AM
RC pilot by soul
Israel
Joined Apr 2005
2,494 Posts
Yep, medusa motors can exceed their ratings by A LOT if cooled well, and used with proper throttle management.
i3dm is offline Find More Posts by i3dm
Old Oct 13, 2008, 11:52 AM
I buy, I fly, I buy....
Wingwrecker's Avatar
United States, OH, Toledo
Joined Feb 2008
1,969 Posts
Doppler reads the sound portion of a recording to determine speed. Not extremely accurate from what I've read, but lots of people use it in lieu of radar.
Wingwrecker is offline Find More Posts by Wingwrecker
Closed Thread


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Wanted Multiplex funjet ouluckydogu Aircraft - Electric - Jets (FS/W) 7 Jul 24, 2006 04:01 PM
Sold Multiplex Funjet NIB bruff Aircraft - Electric - Airplanes (FS/W) 4 Jul 06, 2006 04:46 PM
Video Multiplex FunJet - Full video (20 MB) Jeremy Z Electric Plane Talk 0 Jun 28, 2006 01:27 AM
Video Multiplex FunJET Indoor Jurgen Heilig Electric Plane Talk 2 May 01, 2006 06:31 AM