Brushless Baja with 2 Castle 1717s? - RC-Monster Forums

KaztheMinotaur · **Brushless Baja with 2 Castle 1717s? -** 12.21.2010, 08:35 PM

What are your initial thoughts on a brushless Baja running (2) Castle 1717s on 6s?

coolhandcountry · 12.21.2010, 08:41 PM

Go bigger and single motor.

Bondonutz · 12.21.2010, 08:48 PM

+1
Mo Bigger Mo better

12.21.2010, 08:56 PM

How many cells can a 1717 handle?

lincpimp · 12.21.2010, 11:31 PM

Well, you will have to have some small pinions and may run into issues getting the larger diameter 1717 to physically fit with those small pinions. Keep in mind the gas engine never gets much over 25k rpm, and the 1717 on 6s would be doing 35k or so. Maybe go down to 5s for 29-30k rpms? Just a thought... I would go for 6s and lower gearing, longer runtimes...

Stock pinion size is 18 IIRC, so you would need to go down to a 12t or so. Maybe throw that into BG's speed calc and see what it gives you?

As for power, I see no reason why 2 1717 motors would not move the baja just fine. A BL baja would not be twice as heavy as my lst and the 1 1717 I have in there throws it around.

2 1717, 2MMM and 2 of the zippy flightmaxx 5000mah 40c 6s lips would make a nice setup. Given the cost of 1717 motors right now you could almost buy all of the motors, escs, and lipos for the cost of a 22 series neu... 140 for the motors, 240 for the escs and 200 for the lipos. 580 total...

Keep in mind the dual vxl and similar emaxxs run just fine.

KaztheMinotaur · 11:39 PM

I'm trying to decide on that vs. a Leopard 5692 730KV on 12S. Probably use a Phoenix ICE 160HV w/ Pistix if I did that.

KaztheMinotaur · 12:26 AM

Theoretically the Leopard will produce 4882 watts and the (2) 1717s will produce a total of 5328.

The 1717 setup will weigh 1.1 pounds more.

lincpimp · 12.22.2010, 02:03 AM

Quote:

Originally Posted by KaztheMinotaur

Theoretically the Leopard will produce 4882 watts and the (2) 1717s will produce a total of 5328.

The 1717 setup will weigh 1.1 pounds more.

Hmm, if the 1.1 lbs is mainly motor then you will have a much more powerful system with the 2 1717 motors. OSE claims 3000watts from that leopard. I have a feeling that the 1717 would easily overpower that leopard. Why not go with 2 1520 castle motors? Easier to package than the 1717...

JERRY2KONE · **love to see it. -** 12.22.2010, 02:17 AM

I would just love to see this thing opperate with two 1717's. This is what prototyping is all about, right? Give her a shot and share your results with us.

12.22.2010, 05:02 AM

I'd say go for it! Two 1717s will beat a single Leopard motor any day. You do run into issues using two motors on a single gear though, I think I read somewhere on here that if the motors aren't within 3% they end up just fighting each other and you get a worse result.

lincpimp · 12.22.2010, 01:58 AM

From what I have read the leopard motors are not all that great...

Best part of the dual 1717 and MMM would be motor brakes and reverse. With a decent radio you could even setup a mix for front mech brakes and then be able to switch it off for reverse... That way you would have 4 wheel braking.

Arct1k · 12.22.2010, 10:21 AM

Honestly I think 2 x 1717s would do fine... the motors are cheap and 2 MMM,s is about the same or less than a MMM-XL

The challenge will be getting a motor mount made...

Although I was wondering about doing dual MMM-XL and Castle 1/5th scale motors for a bit of fun... I could ask mike what it would take to create a motor mount.

KaztheMinotaur · 12.22.2010, 10:27 AM

Kershaw Designs conversion can accomodate 2 1717s.

Can the 1717 run 7S?

Arct1k · 12.22.2010, 11:37 AM

Maybe but rated for 6S... Good luck with that but I much prefer mike's setup.

lincpimp · 12.22.2010, 01:44 PM

Had a look at the kershaw setup. Looks interesting.

Anyone know what size pinion he isusing to interface with the stock baja spur? Something like an 18t mod 1.5? That seems close to stock, IIRC.

Looks like he has a few options on spur sizes for the gear reduction, 40, 45, 50, 54, 60. He is using mod 1 gears by the look of it. So given the use of the 5mm shaft on the 1717 the largest easily obtainable pinion will be a 26t. If you calculate the distance between a 40t spur and 26t pinion, centerline to centerline you get 35mm, which should be enough to clear the 50mm diameter 1717, and the layshaft.

Here is the rc calc with my best guess of an 18t mod 1.5 pinion. Factored that the ratio of 18/57 is 3.166666, and then used the spur/pinion section to calculate the gear reduction section.

Differential Ratio: 1
Transmission Ratio: 2.4000000000000003
Other Ratio: 3.16666
Spur Tooth Count: 40
Pinion Tooth Count: 26
Total Voltage: 22.20
Motor KV: 1580
Tire Diameter (inches): 5.311
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor Coil Resistance: 0
Spur/Pinion Ratio: 1.54 : 1
Total Ratio: 11.69228 : 1
Tire Circumference (inches): 16.68 inches (423.8 mm)
Rollout: 1.43:1
Total Motor Speed: 35076 RPM
Vehicle Speed: 47.4 mph (76.14 km/h)
Effective KV Value: 1580

Check my numbers and see if that makes sense... Thought the baja 5b tires were taller than 5.3... I just used the numbers in the calc's drop down menu.

If so unless much larger pinions, or more voltage is used this will not be all that fast... I would like to see alot closer to 1:1 ratio on the gear reduction, however going much smaller with the spur will cause issues getting the gears to mesh with the 1717 motor diameter. Unless we can run alot larger mod 1.5 pinion where it meshes with the factory baja spur.