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HelicopterCentury Radikal G20-30 N640 Hawk Predator › Radikal Gear Ratio and Batteries
06-04-2010 04:58 AM  7 years agoPost 21
bobmoser

rrApprentice

Edmond, OK

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Gear/Batts.

Go with the 6.4 gear ratio and I use a 4.8v NiMH 2300 mAh for the EI and run a 7.4v lipoly 3600 mAh with an Arizona regulator for electronics. Those servos you got are pretty power hungry. Spend some time with the break-in and your going to love this heli. Great choice for a first one, you get to spend tons of time working on the hover skills while you break the engine in and then move on to the real flying after. Good luck and have fun, I sure do with this thing.

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06-04-2010 05:37 AM  7 years agoPost 22
teekay18

rrNovice

Northwestern​Ontario, Canada

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Thanks bobmoser!

I am going to use the 6.4 ratio. I have read that these servos are pretty power hungry, I'm hoping a 4.8V NiMH 3000mAh or 4200mAh will do the trick for them and a 4.8V NiMH 3000mAh for EI, I'm trying to keep it as simple as possible without regulators for now.
Great choice for a first one, you get to spend tons of time working on the hover skills while you break the engine in
Another reason I thought it would be a good choice, it would give me lots of time to get the hang of it with all the hovering it'll take. I'm very much looking forward to the break in process, getting to know the ins and outs of the engine.

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06-04-2010 01:44 PM  7 years agoPost 23
bobmoser

rrApprentice

Edmond, OK

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Battery pack

I tried a 4.8v NiMH 2300 mAh pack with my electronics once. Almost lost the whole thing when the receiver rebooted due to so much power draw from the servos. After that I decided to step it up to the 7.4v Lipoly and regulator. My regulator is set at 6.0V and rudder is running around 5V. I just don’t trust the smaller NiMH packs with those power hungry servos anymore. Granted my battery pack was a lot smaller than what your planning on using.

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06-04-2010 05:05 PM  7 years agoPost 24
oldfart

rrProfessor

Vancouver, Canada

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I tried a 4.8v NiMH 2300 mAh pack with my electronics once. Almost lost the whole thing when the receiver rebooted due to so much power draw from the servos
The problem I found with NiMh batteries is that there are so many types of them that the word NiMh should not be used in a general term for our applications.

One type of NiMh will do great for a particular application while another will be a dangerously dismal failure.

Some types are designed for LOW amperage draw and charging (slow charging only) for the purpose use in certain appliances that have low current draw but will not need recharging very often - those we used to find in electric shavers for example. Unfortunately, many various sized of these are sold every day to the unsuspecting modeler. Why, because they can spec them as having a very high mah rating for their size. But they will not be up to the task of powering our flight packs.

In Lipo's we have the C rating for this, but NiCds and NiMh where never sold with a "C" rating. SO the type above would be considered a very low C cell.

On the other hand, there are other types of NiMh batteries that are specially designed for high amp use and high amp type of fast charging (e.g. as sold for powering drive motors in the bigger electric cars). These are much bigger and heavier for the same mah ratings as those above - they are the same size as the bigger 2400 mah nicd's. These will work very well powering a flight pack of fully digital servos. In the LiPo world, these would have a relatively high C rating.

They also have very different charge criteria then the NiCds. Specially for the high current use. They must be firstly conditioned by cycling them at least 3 times (preferably 5 times) at a 0.5C. Then they will gladly put out the current and mah that they where rated for.

Phil

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06-04-2010 05:19 PM  7 years agoPost 25
teekay18

rrNovice

Northwestern​Ontario, Canada

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Thanks for the clarification Phil!

I was planning on using Sub-C NiMH batteries for both the EI and electronics. I was looking at the Sanyo 3000 HRSCU which is full Sub-C with a 7.0 mOhms impedance rating, does this sound like a good battery for the job ?

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06-04-2010 05:24 PM  7 years agoPost 26
Zman

rrKey Veteran

Florida

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Just another option to consider TK. I have and know several others who have been using the A123 life packs. On my radikals, I have a 6.6v 2100 on receiver and a 1600 A123 on ignition. If using stock ignition, you will need to bring that voltage down to 5v or so. Nice thing about life packs is they are lightweight and you can safely charge at 2 or 3c making for a quick recharge. Just an option.

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06-04-2010 05:37 PM  7 years agoPost 27
teekay18

rrNovice

Northwestern​Ontario, Canada

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Thanks for the suggestion Z, I've looked into A123 life packs and Lipos, the only thing holding me back from using these batteries is that fact that I am trying to keep things simple without regulators or stepdowns, even if it is simple to wire them in, it's just one less thing for me to worry about. Maybe in the future when I get better at flying I'll try some newer battery setups.

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06-04-2010 05:45 PM  7 years agoPost 28
Zman

rrKey Veteran

Florida

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I do step down the ignition pack but run the heli on 6.6v .....But you got the right idea, use what you are comfortable with.

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06-06-2010 09:08 AM  7 years agoPost 29
teekay18

rrNovice

Northwestern​Ontario, Canada

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Servo Horns

What would be the best(strongest?) servo horn to use on the jr 8717 cyclic servos that would accommodate the radikal Pitch Compensators using 4 screws without having to drill new holes ?

Thanks.

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06-06-2010 05:05 PM  7 years agoPost 30
oldfart

rrProfessor

Vancouver, Canada

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Thanks for the clarification Phil!

I was planning on using Sub-C NiMH batteries for both the EI and electronics. I was looking at the Sanyo 3000 HRSCU which is full Sub-C with a 7.0 mOhms impedance rating, does this sound like a good battery for the job ?
Yes, charged and cycled properly at the beginning, those would be fine.

Phil

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06-08-2010 07:52 PM  7 years agoPost 31
teekay18

rrNovice

Northwestern​Ontario, Canada

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Servo Horns

Servo Horns

What would be the best(strongest?) servo horn to use on the jr 8717 cyclic servos that would accommodate the radikal Pitch Compensators using 4 screws without having to drill new holes ?

Thanks.
Any suggestions ?

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06-15-2010 02:45 PM  7 years agoPost 32
Whtfld

rrNovice

Gainesville,GA USA

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gear ratios

My Radical is HD Carbon. 90 tooth main, 16 tooth pinion, 620 Rotortechs. Whats the problem with this setup?

I like my TOYS. No such thing as too fast!!

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06-15-2010 02:49 PM  7 years agoPost 33
Zman

rrKey Veteran

Florida

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What kind of flying do you plan to do? With a 5.6 gear ratio, you will need to run a scary head speed if you want the engine in its "zone". If you arent after performance, then you will probably be okay running around a 1900 head speed although the engine will only be running around 10500rpm or so. The sweet spot for the stock engine if you are after performance is 12000 to 12500k engine speed.

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06-15-2010 03:08 PM  7 years agoPost 34
Whtfld

rrNovice

Gainesville,GA USA

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gear ratios

Thanks Zman. I mainly sport fly working to 3d. So I guess I should get the 13 or 14 tooth pinion.

I like my TOYS. No such thing as too fast!!

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06-15-2010 03:13 PM  7 years agoPost 35
Whtfld

rrNovice

Gainesville,GA USA

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redirect airflow mod?

Where is this redirect mod posted?

I like my TOYS. No such thing as too fast!!

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06-15-2010 03:16 PM  7 years agoPost 36
Zman

rrKey Veteran

Florida

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No problem. I would go with the 14, should work great. The redirect mod is in the radikal FYI which is a sticky in this forum.

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06-28-2010 04:15 AM  7 years agoPost 37
teekay18

rrNovice

Northwestern​Ontario, Canada

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Questions ??

I'm about to make an order for all the remaining things I need for my radikal. The one thing I'm still unsure about and was hoping someone could point me in the right direction is what servo horns for my JR 8717's will accommodate the radikal pitch compensators without having to drill new holes? I can't seem to find any that list the dimensions I need.

Which one do I use for frame support between the canopy stand offs, the Aluminum Post(Part# HI6031S), or Frame Support Bar(Part# HW6113AS) or will either one of these work ? Also what screws do I need for them because there needs to be threads on both ends ?

Is it necessary to have switches for the RX and EI ? or would I be able to do without them ?

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07-01-2010 10:59 PM  7 years agoPost 38
teekay18

rrNovice

Northwestern​Ontario, Canada

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I ordered everything else I needed

I'm still wondering if it's okay if I go switchless on the RX and EI ??

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07-02-2010 11:08 AM  7 years agoPost 39
Zman

rrKey Veteran

Florida

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Sure it is. I prefer it, one less possible fail point. Just make it where the leads can be fairly easy to get to.

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07-02-2010 02:22 PM  7 years agoPost 40
Climax

rrVeteran

West London, United​Kingdom

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So which post did you buy in the end to put between the cannopy supports?

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