Register Now

maui80 · 02-21-2012, 12:50 PM

Hi what the price for the bell conversion?

Is possible buy One with shipping in italy?

TomC · 03-25-2012, 11:04 PM

I don't mean to rain on anyones parade but this belt mod looks like a recipe for disaster imho. The belt pulley ratios are way too high (72/16 = 4.5:1). By comparison, the SAB Goblin is 60/22 = 2.7:1

The main problem with high pulley ratios is that the contact area on the small pulley becomes too small (not too many teeth of the belt actually on it). This is going to require pretty high belt tension which will result in pretty poor belt life, poor eff/power, and high motor temps. The fact that this mod uses a wider belt, compared to the Goblin may help a little bit.

For your sake I hope I'm wrong, but I don't think so.

Cheers,
TomC

osat · 03-26-2012, 12:40 PM

There is no problem to run down to 13T pinion because there is belt tensioner. I`m flying it with 14T pinion for one year and no problem at all.

TomC · 03-26-2012, 03:30 PM

Quote:

Originally Posted by osat

There is no problem to run down to 13T pinion because there is belt tensioner. I`m flying it with 14T pinion for one year and no problem at all.

So, you have been running this belt mod for one year now with a 14t motor pulley and 72t secondary pulley (~5:1 ratio) with no problems?

Cheers,
TomC

desertstalker · 03-26-2012, 11:05 PM

Quote:

Originally Posted by TomC

So, you have been running this belt mod for one year now with a 14t motor pulley and 72t secondary pulley (~5:1 ratio) with no problems?

Cheers,
TomC

See https://www.helifreak.com/showpost.p...7&postcount=44 and following

There is an idler pulley to make the belt wrap farther around the motor pulley, so shouldn't be an issue with contact there. The Protos uses a similar setup and gets around 6:1 (IIRC) without issue.

TomC · 03-27-2012, 01:21 AM

Quote:

Originally Posted by desertstalker

See https://www.helifreak.com/showpost.p...7&postcount=44 and following

There is an idler pulley to make the belt wrap farther around the motor pulley, so shouldn't be an issue with contact there. The Protos uses a similar setup and gets around 6:1 (IIRC) without issue.

Thanks desertstalker. To be honest I did not see this idler, lol! Should help quite a bit. Still going to need quite a bit of belt tension and hence belt and bearing wear may be an issue in the long run imho.

I have looked at and flown a local guys Protos 500 and as much as I don't like belts, I had to agree that it seemed to work fine. Not sure how the Protos 500 design (~1.5kw power) is going to translate to much larger 8-10kw power heli's though? Guess we'll find out with the Protos 700!

Thanks again and cheers,
TomC

mkovalcson · 03-27-2012, 08:18 AM

Frankly I think the Protos design starts to lose its appeal in a larger heli.

I really like it for a beater heli as it is very easy to repair and pretty bulletproof, but it doesn't have long flight times.

In a larger heli I think efficiency is more of an issue.

helicraze · 03-27-2012, 02:42 PM

I could not believe how it does not spin easily (protos), the 700 main gear can used as a serving platter

mkovalcson · 03-27-2012, 06:54 PM

Quote:

Originally Posted by helicraze

I could not believe how it does not spin easily (protos), the 700 main gear can used as a serving platter

I was just getting excited about bringing my TDR in after 5 minutes of flight at 48% throttle and having 72% left in the batteries!!!! Looks like I can fly at this setting for 10 minutes and not be in danger. Very Cool!!!! It responds very well at this speed but it not hyperactive. It's actually very relaxing and confidence building to fly at this speed. I think I'll hang around at this speed for a month or two before bumping it up to 60% throttle.

My Protos 500 is spent at about 4.5 minutes and typically comes back at about 3.8V, but it's running a pretty hot head speed.

TomC · 03-28-2012, 01:40 AM

Quote:

Originally Posted by helicraze

I could not believe how it does not spin easily (protos), the 700 main gear can used as a serving platter

Ya, I'd hate to have to auto one in!

BTW, how free-wheeling is Craig's TDR (with this belt mod) compared to stock? Also, compared to your now broken-in Goblin? Thanks.

Cheers,
TomC

helicraze · 03-28-2012, 05:01 AM

The TDR with belt free wheels fine as far as i know. The goblin not very well, due to belt and brass bush surrounding one way

TomC · 03-28-2012, 05:42 AM

None of these belt drives are going to free-wheel as well as a properly meshed geared system imho. Same goes with a belt vs a TT tail.

helicraze · 03-28-2012, 06:29 AM

A first stage belt drive has no effect on drag in an auto, the 2nd stage that spins in an auto is a pinion and gear one both tdr and goblin.

HSC · 03-28-2012, 08:30 AM

Well boys, I have belt drive hear and it works pretty fine for 30 starts (just read out j_log files), but I do not have particulary strong motor (rewinded MX 700 ), only 8kw in spikes.
There is plenty of mashing hear thanx to bigg diameter tensioner, soo no problems at all with jumpowers !
I have now tension set too 80 N and it works prety fine ( data sheet for belts say 150N, but I thing is a bit too much).
The true is wee have tested several diferent producers of belts, some are good (dinadrive and contitech) some not soo ( 3M ).
Soo up to date works for mee just fine.......

TomC · 03-28-2012, 12:55 PM

Quote:

Originally Posted by helicraze

A first stage belt drive has no effect on drag in an auto, the 2nd stage that spins in an auto is a pinion and gear one both tdr and goblin.

Your right mate. I was still thinking about the Protos, lol! Just the belt-driven tail like on the Goblin (or Diablo) is going to adversely effect the auto, esp. if the belt tension is a little high.

Quote:

Originally Posted by HSC

Well boys, I have belt drive hear and it works pretty fine for 30 starts (just read out j_log files), but I do not have particulary strong motor (rewinded MX 700 ), only 8kw in spikes.
There is plenty of mashing hear thanx to bigg diameter tensioner, soo no problems at all with jumpowers !
I have now tension set too 80 N and it works prety fine ( data sheet for belts say 150N, but I thing is a bit too much).
The true is wee have tested several diferent producers of belts, some are good (dinadrive and contitech) some not soo ( 3M ).
Soo up to date works for mee just fine.......

Good to hear it's going well and you are experimenting with diff belts. Your large idler (tensioner) is a good idea, as is your wide belt, but it still will require a fair amount of belt tension which is going to adversely effect overall eff's and belt life. If you could do a few logs before/after you might see this diff. I'd still expect motor temps to be a bit higher as well. Please let us know how the next 30 flights go. Thanks.

Cheers,
TomC

johnjonfenomenon · 04-06-2012, 05:22 AM

Ok so my name came up on the list to buy one .. Now based on my calculations using the ready heli HS calculations and the info provided to me the main gear is a 72t and the pinion option is (14,15,16) Given this calculation with the stock pyro 700-52 setup using a 12s 45c battery, the lowest hs on a 14t to be 3764

.. Can soeone explain to me what I am missing or actually calculate for me the best pinion option to obtain HS of 1450 - 2150. This will be governed by a helijive 120.

Thanks,
John

AcidDrink · 04-06-2012, 05:34 AM

Quote:

Originally Posted by johnjonfenomenon

Ok so my name came up on the list to buy one .. Now based on my calculations using the ready heli HS calculations and the info provided to me the main gear is a 72t and the pinion option is (14,15,16) Given this calculation with the stock pyro 700-52 setup using a 12s 45c battery, the lowest hs on a 14t to be 3764

.. Can soeone explain to me what I am missing or actually calculate for me the best pinion option to obtain HS of 1450 - 2150. This will be governed by a helijive 120.

Thanks,
John

Two stage power drive.
Please refer to the post below for correct info.

johnjonfenomenon · 04-06-2012, 05:58 AM

Quote:

Originally Posted by AcidDrink

Two stage power drive.
Put main gear size 160.65 and all will start to make sense.

Thanks Thats the number I was looking for.

Stolla · 04-06-2012, 06:14 AM

That will only help with the stock gear not with the 72t belt, formula for belt (and gear)
72(belt teeth) divided by pulley t count (16 tpulley =14tgear) x 2,55 will give you the correct ratio. For the pyro you want 16t.

AcidDrink · 04-06-2012, 07:39 AM

Quote:

Originally Posted by Stolla

That will only help with the stock gear not with the 72t belt, formula for belt (and gear)
72(belt teeth) divided by pulley t count (16 tpulley =14tgear) x 2,55 will give you the correct ratio. For the pyro you want 16t.

That's correct. Sorry, I shouldn't reply to posts when I am half asleep.

03-25-2012, 11:04 PM	#122 (permalink)
TomC Registered Users Join Date: Apr 2005	I don't mean to rain on anyones parade but this belt mod looks like a recipe for disaster imho. The belt pulley ratios are way too high (72/16 = 4.5:1). By comparison, the SAB Goblin is 60/22 = 2.7:1 The main problem with high pulley ratios is that the contact area on the small pulley becomes too small (not too many teeth of the belt actually on it). This is going to require pretty high belt tension which will result in pretty poor belt life, poor eff/power, and high motor temps. The fact that this mod uses a wider belt, compared to the Goblin may help a little bit. For your sake I hope I'm wrong, but I don't think so. Cheers, TomC __________________ Blade nQX,mCPX-BL,450x,500x Bell 222(bd3sx),550x(bd3sx) TT X50E, 10s, bd3sx Ion-x, Actro 32-3, SS, 10:1, PJazz esc, 10s Now also a FPV addict; Quads and Planes (soon to try heli's!) Last edited by TomC; 03-26-2012 at 03:27 PM..

03-27-2012, 08:18 AM	#127 (permalink)
mkovalcson Registered Users Join Date: Apr 2011 Location: US	Frankly I think the Protos design starts to lose its appeal in a larger heli. I really like it for a beater heli as it is very easy to repair and pretty bulletproof, but it doesn't have long flight times. In a larger heli I think efficiency is more of an issue. __________________ Mark Dusty Shelf queens: TDR2, TDR, Protos Max, Logo 550SX, Protos 500, Jeti DS-16, etc....

03-28-2012, 08:30 AM	#134 (permalink)
HSC Registered Users Thread Starter Join Date: May 2006	Well boys, I have belt drive hear and it works pretty fine for 30 starts (just read out j_log files), but I do not have particulary strong motor (rewinded MX 700 ), only 8kw in spikes. There is plenty of mashing hear thanx to bigg diameter tensioner, soo no problems at all with jumpowers ! I have now tension set too 80 N and it works prety fine ( data sheet for belts say 150N, but I thing is a bit too much). The true is wee have tested several diferent producers of belts, some are good (dinadrive and contitech) some not soo ( 3M ). Soo up to date works for mee just fine....... __________________ A je to ?

04-06-2012, 05:22 AM	#136 (permalink)
johnjonfenomenon Registered Users Join Date: Oct 2010	Can someone help me with calculating the HS Ok so my name came up on the list to buy one .. Now based on my calculations using the ready heli HS calculations and the info provided to me the main gear is a 72t and the pinion option is (14,15,16) Given this calculation with the stock pyro 700-52 setup using a 12s 45c battery, the lowest hs on a 14t to be 3764.. Can soeone explain to me what I am missing or actually calculate for me the best pinion option to obtain HS of 1450 - 2150. This will be governed by a helijive 120. Thanks, John __________________ After every crash just remember .. “We can rebuild him. We have the technology. We can make him better than he was. Better..stronger..faster.” Intro from Six Million Dollar man RIP Roman Pirozek Jr. 1/11/94 - 9/5/2013

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

02-21-2012, 12:50 PM	#121 (permalink)
maui80 Registered Users Join Date: Feb 2007	Hi what the price for the bell conversion? Is possible buy One with shipping in italy?

03-26-2012, 12:40 PM	#123 (permalink)
osat Registered Users Join Date: Jan 2009	There is no problem to run down to 13T pinion because there is belt tensioner. I`m flying it with 14T pinion for one year and no problem at all.

03-27-2012, 02:42 PM	#128 (permalink)
helicraze Registered Users Join Date: Apr 2008	I could not believe how it does not spin easily (protos), the 700 main gear can used as a serving platter

03-28-2012, 05:01 AM	#131 (permalink)
helicraze Registered Users Join Date: Apr 2008	The TDR with belt free wheels fine as far as i know. The goblin not very well, due to belt and brass bush surrounding one way

03-28-2012, 05:42 AM	#132 (permalink)
TomC Registered Users Join Date: Apr 2005	None of these belt drives are going to free-wheel as well as a properly meshed geared system imho. Same goes with a belt vs a TT tail.

03-28-2012, 06:29 AM	#133 (permalink)
helicraze Registered Users Join Date: Apr 2008	A first stage belt drive has no effect on drag in an auto, the 2nd stage that spins in an auto is a pinion and gear one both tdr and goblin.

04-06-2012, 06:14 AM	#139 (permalink)
Stolla Registered Users Join Date: Jul 2009	That will only help with the stock gear not with the 72t belt, formula for belt (and gear) 72(belt teeth) divided by pulley t count (16 tpulley =14tgear) x 2,55 will give you the correct ratio. For the pyro you want 16t.

Register Now

Log-in