A few questions on a FASTech.

I have a mostly stock FASTech. It has a 60A Seaking ESC v1 in it and my Spektrum Rx.

The plan is to put in a 642 prop from Egneg, and was wondering if the ESC will handle it? Stock motor, I have 2x 2S 5000mAh and 2x 2S 3800mAh batts in series.

Next, I read that the brass insert in the stock prop will make the Octura prop fit, but it seems pretty fixed in there - do I just whack it out, or grind away the plastic prop? Can I buy the brass bushings anywhere?

I have bent the turn fins, as posted here. Other than that is there any other recommendations for a new guy?


Jason

-X642 will work with your ESC fine on 4S
-if your batts are LiPo in series you are running 4S right? If so you are ok
-the adapter inside of the prop shoud come out with a little more than little push and yes it will be fine with X642
-try pushing it with wood stick that will grab the inside area of the prop
-for replacement prop adapter try contacting Horizon or here with Steve OSE

Cheers
Robert

just be careful with prop adapters, the OD of the shaft on the FASTech is 3mm and not 1/8" (3.175mm), you can make the difference with a piece of paper.

I believe the HH prop adapter is 3mm ID and 3/16" OD, while OSE might have 1/8" to 3/16".

Quote:

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Originally Posted by schnellschnell

I have a mostly stock FASTech. It has a 60A Seaking ESC v1 in it and my Spektrum Rx.

The plan is to put in a 642 prop from Egneg, and was wondering if the ESC will handle it? Stock motor, I have 2x 2S 5000mAh and 2x 2S 3800mAh batts in series.

Next, I read that the brass insert in the stock prop will make the Octura prop fit, but it seems pretty fixed in there - do I just whack it out, or grind away the plastic prop? Can I buy the brass bushings anywhere?

I have bent the turn fins, as posted here. Other than that is there any other recommendations for a new guy?


Jason

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The 5000mah are fine, but the 3800mah batts might be to low and not supply enough amps, all depends on there c rating but they are pretty low. If they are not up to the task bad things can happen i.e lipo failure which could result in the loose of possible esc & motor.

The 3800 batts are 35c, and get a bit warm after a run but nothing worrisome.

And I managed to get the brass bushing out of the stock prop - just a bit of a whack - thanks for the tip!

j

Quote:

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Originally Posted by schnellschnell

The 3800 batts are 35c, and get a bit warm after a run but nothing worrisome.

And I managed to get the brass bushing out of the stock prop - just a bit of a whack - thanks for the tip!

j

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When you add that x642 prop, your amp load is going to go up. The prop has more pitch and a little more diameter over the stock prop and does not flex under load like the plastic stock prop will. What's that all mean, if your 3800's are getting a bit warm on the stock setup, its only going to get worse with the x642... JMO

Diesel, I thought the heat was helped by higher C ratings, not the capacity. How does the battery capacity relate to heat under load?

j

Quote:

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Originally Posted by schnellschnell

Diesel, I thought the heat was helped by higher C ratings, not the capacity. How does the battery capacity relate to heat under load?

j

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A lot of people think mah is just like a gas tank based just on runtime. That's a half truth, but more importantly the mah x c rating will tell you how much amperage your batteries can deliver. The higher amp load the better. Your 3800s have a good c rating so they can supply over 100amps cont which is good for your application, but more mah and c rating the better. The more amps from batts the less stressed they will be and less overworked. When they get overworked because they can't supply enough amps then they heat up a lot and possible puff and/or fail.

aH x c rating = amps.

3.8 (3800mah) x 35 = 133amps

133 x 80% (lipos are never discharged fully so 80% is typically used and needs accounted for) = 106amp. So a good guess is your lipos are suppling roughly 106 amps to your system. Now your motor can spike in the 60 amp range depending on prop/driving/setup ect. So your batteries are doing there job for this application, but in a different setup they may struggle and a larger prop may work them harder. Always try and get the biggest mah and highest c rating you can efford. (and make sure the larger mah packs will fit in your hull lol).

Another question people ask is well my batteries are putting out 100+ amps but my esc is only rated at 45amps. The esc's amp rating is related to amount of amps the motor can pull not the amount of amps the batts can supply. More amps from the battery the better! Another thing that can happen if the batts can't supply the system with enough amps is the motor will pull amps and the batteries can't supply that demand the esc gets caught in the middle of a tug-of-war between the motor and batts and poof she goes.

Hopefully this makes some sense.