RunRyder - Intrepid Gas Gear Ratios

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Bergen R/C Helicopters > Intrepid Gas Gear Ratios

heli_headcase
Veteran
Location: Hovering around Atlanta

It's too quiet in this forum - time to blow out the dust...

I'm in need of a gear ratio change in my gas Intrepid. Stock gearing, engine-to-main is 14/90 or 6.43 to 1. I need to go higher, more engine revs per main rotor revs. The four-bladed rotor setup (see my gallery) loads the engine too much and I'd like to give it a little break.

What gear combinations are available that will fit the existing engine adjustment slots in the frames? I'd rather not extend the slots.

Thanks,
Steve
.
.

HHC

So many heli's - too little time...

10-02-2006 08:04 AM

PaulH-MA
Veteran
Location: Boston, MA

Bergen offers the following pinions: 10T, 11T, 12T, 13T, 14T. Just go to their web site and type "Pinion" in the search box at the top of the page.

To clarify, you need a higher ratio, which is acheived through a lower tooth count on the pinion.

I do recall someone with an Intrepid Turbine running a four-blade head. I don't remember what pinion was used in it.

--Paul

TREX 450
Bergen Intrepid Gasser x2

10-02-2006 12:53 PM

charger
Senior Heliman
Location: Spencer MA.USA

I have two Bergen Intrepid camera ships using the 12T running NHP800 and V810,I also using a 14t on another Bergen Intrepid with 710V-blades.
All have G-26 engines,1 camera ship is Hanson balanced The other two are a Hanson Pro and Hanson (Al great guy)Pro plus
Agree on too quiet in this forum

Old chinese proverb.don't dwell on past crash, but look forward to future flight

10-02-2006 09:44 PM

heli_headcase
Veteran
Location: Hovering around Atlanta

Main gear info missing

Hi PaulH-MA,

As mentioned in my first posting, I'm trying to keep the distance relationship between the clutch pinion and main gear so the frames can escape being modified. any reduction in pinion diameter (or tooth count) will force the engine to sit more aft in the frames. Can't allow that to happen. If anything I'd prefer to slide the engine forward a tiny bit as the cross-mount that's bolted to the cylinder head is hard against the back edge of the adjustment slot.

I've seen no link to any larger main gears from Bergen. It's either 90T or nothing, correct? By drilling two new holes I can use a Miniature gear if one exists in the required tooth count.

Hi charger,

The 7.5-1 ratio of your camera ship sounds pretty good but again, the smaller clutch pinion must be combined with a larger main gear so the engine can stay forward. A 13T pinion and 93T main may work, gives a 7.15-1 ratio. Could be a good compromise and minimal shift in engine position. Let's see... 11,000 RPM engine, 7.15 ratio gives me 1540 on the head, approx.

How 'bout the stock 14T clutch and a 92T main. 6.57-1, 1670 approx on the head. Nah, that's too close to stock I think but it's an easy test to try and only shifts the engine forward about 1mm. That four blade head has a high parasitic drag and makes the engine work too hard. Time to order some gears and play.

Thanks for the brainstorming session,
Steve
.
.

HHC

So many heli's - too little time...

10-02-2006 10:17 PM

PaulH-MA
Veteran
Location: Boston, MA

All you have to do to modify the frames is elongate the holes a little. It's actually a pretty common thing to do. Moving the engine back the milimeter or so that it will need isn't going to throw your balance off by much, if at all.

Bergen only sells one main gear that I am aware of.

--Paul

TREX 450
Bergen Intrepid Gasser x2

10-02-2006 10:27 PM

heli_headcase
Veteran
Location: Hovering around Atlanta

Balance isn't the issue here...

Hi Paul,

The reason I don't want to change the holes sizing has nothing to do with balance. It's a policy of mine to make the fewest permanent changes possible in a heli unless there's no other choice. I collect heli's and would rather keep them in an easy-to-restore condition (just bolt the parts back where they came from) when ever possible.

Also there's the factor of glass dust being spread around. Carving on the frames will dirty things up and I'm not in the mood to take the frames back apart to do a clean job of it.

I think I've decided on a 13T pinion and 92T main. I'll have to set my lathe up and modify a misc plastic main gear (Don't know what it goes to - Gohbee maybe?) so it can fit Bergen's constant-drive main gear assembly. Would rather simply bolt something together but it's not to be.

Anyone else want to jump in here before I purchase parts?

Thanks,
Steve

HHC

So many heli's - too little time...

10-03-2006 08:22 PM

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Bergen R/C Helicopters > Intrepid Gas Gear Ratios

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