New Bix3 Owner - Prop/Motor/ESC Question

[MPSchenck]

Hello All - THIS IS MY 1ST POST ON THE FLITE TEST FORUMS! - Sorry for the shouty caps, but it's good to be here officially and no longer lurking.

I've been flying RC planes for a month or so, before that just small helis and a quad.
I started planes with a Sport Cub S w/ SAFE then I got a UMX Radian for Christmas.

Those are very fun, but I wanted something bigger, plus flaps. So...
I ordered the Bix3 PNF, a 2200 3S, and a couple of MG analog 9g servos from HobbyKing and a Lemon DSMX 7Ch w/ stabilizer from Lemon on Jan 10th. The HobbyKing order arrived on Jan 14th, but I'm still waiting on the Lemon. I was kind of disappointed to learn they are shipped from Hong Kong, but hoping for a US warehouse was a little much, I guess.

The night I got the plane I stripped all the decals, assembled it (minus the landing gear), installed the flap servos, epoxied in the wing spar tubes, and taped the leading edges of the wings and the horizontal stabilizer plus the bottom of the fuse - all with extreme packing tape. I also painted the FPV canopy black. And now she sits waiting.

I have, in the meantime, read almost every post in the RCGroups Bix3 thread, and looked through all the Flite Test threads about the Bix3.

I have almost no experience with brushless motors, just 1 RC car (that is an inrunner), but even I think the Bix3 motor seems very cheap, plus all the posts and videos of the vibration all but prove it. I actually think it's binding against the foam a little.

Surprise, surprize I want to change my motor.
I also would like very long run times per battery. Like I said earlier, I have read almost every post in the thread over on RCGroups and I've payed attention taking some very brief notes.

Sorry I don't know who posted these over there…

For more duration and less noise, go for a 8x6 or 9x6 APC (style) prop and appropriate motor, say a 2830mm/2836mm 950-1050KV outrunner.

...and efficient prop (8" or 9") and a 2830 or2836mm outrunner of 1000-1100KV keeping the power down to 130-200watts...

...2830mm 1000kv motor with an APC 8x6. Cruising around 4-5 amps equalling 20-25 minutes on a 2200mAh battery...

Yesterday I ordered the Small Parts CNC Bix3 Adjustable Motor Mount, which if you aren't familiar lets you mount up to a 10" prop. I'm about to pull the trigger on the motor and essentials order and need some confirmation that I'm on the right track, and not about to blow the thing out of the sky.

Short List w/ Links
APC style propeller 9x6-E http://tinyurl.com/pxsejhv
APC style propeller 8x6-E http://tinyurl.com/pg4sodo
Turnigy Aerodrive SK3 - 2836-1040kv http://tinyurl.com/lqbqbng
HobbyKing 30A BlueSeries Brushless Speed Controller http://tinyurl.com/plnb6vh
Turnigy 5000mAh 3S 25C Lipo Pack http://tinyurl.com/pdydno3
HobbyKing Cell Checker with Low Voltage Alarm http://tinyurl.com/l4yg7lx

(I actually stopped by my LHS and bought an APC 10x4.7 SFP today also.)

This is my main question...
I'm not sure which prop/motor/ESC would be the best for extended flight times?
I have asked this question over on RCGroups, but I've gotten no real answers so I was hoping the AWESOME and VERY HELPFUL Flite Test Forum crowd could help a newbie out.

Also, I know that is a big battery pack, but it's lighter than some [read: most] dual 2200mAh 3Ss with a parallel harness, but I'm told I wont be able to balance the CG as easily with a single large pack.

Like I said earlier I want super long flight times and, currently, I only kind of want to strap a solo Mobius to the FPV canopy.

Thoughts?

 

[IFlyRCstuff]

Welcome to the forums!!!
The setup should look like this to be most absolutely efficient (almost impossible)
amp draw= minimum on motor= half on ESC+low wing loading all of which is determined by a lipo (usually a 3s)
the motor setup you named seem pretty good and you can expect 15 minutes if you run it a little lean.
Strapping a mobius should be fine, so long as the C.G. is fine (and you can move the battery back accordingly.
Since you have 7 channels you may want to consider crow, camber, reflex and various other combinations.

 

[MPSchenck]

Welcome to the forums!!!.

Thanks!

amp draw= minimum on motor= half on ESC+low wing loading all of which is determined by a lipo (usually a 3s)

I'm sorry, that's the first time I've seen it written (or figured) like that, and I'm confused now more than before.
How do I know what the minimum on the motor is when the site only tell max loading (in this case 28A)?

I just sub'd to eCalc for a year so I'm gonna play around with that for awhile. How accurate is it?

Since you have 7 channels you may want to consider crow, camber, reflex and various other combinations.

I do want to try those.

I'm super interested in powered gliders. My "baby" Radian is pretty awesome, but it feels limited by the lack of ailerons. My plan is after I have a grip on the Bix3 I'm going to set up a Radian Pro or a Phoenix 2000.

 

[quorneng]

MPSchenck
For any given airframe (a Bix 3 in your case) its endurance is basically controlled by just 2 things.
Its weight and its motor/ prop efficiency.
Of course how you fly it makes a difference as well.
Increasing the size of the battery is a trade off. More capacity = long flight times but the extra weight means more power is required so using up some of the extra capacity. At some point the extra weight of the plane will make it un-flyable.
Motor/prop efficiency is also complex. The prop has a most efficient rpm speed as does the motor furthermore this combination then has to be matched to the planes speed and that depends on the its weight.

The power required to fly a given airframe is proportional to the its weight and drag.
You can't do much about the airframe in this case but anything that smooths the airflow will help (as long as it doesn't add any weight!)
Weight is the real key to endurance. Every gram you can save can be transferred to a bigger battery without needing any more power to carry it.

Flying at the most efficient flying speed (in terms of power) will be quite close to the stall. It takes a bit of practise to maintain (too slow, you stall and waste power recovering, too fast and you just waste power!) however it soon becomes pretty boring!

Of course if you build a plane designed with the sole purpose of flying for as long as possible even at Bix 3 sort of size the limit is likely to be your endurance not the planes.

 

[MPSchenck]

MPSchenck
For any given airframe (a Bix 3 in your case) its endurance is basically controlled by just 2 things.
Its weight and its motor/ prop efficiency.
Of course how you fly it makes a difference as well.
Increasing the size of the battery is a trade off. More capacity = long flight times but the extra weight means more power is required so using up some of the extra capacity. At some point the extra weight of the plane will make it un-flyable.
Motor/prop efficiency is also complex. The prop has a most efficient rpm speed as does the motor furthermore this combination then has to be matched to the planes speed and that depends on the its weight.

The power required to fly a given airframe is proportional to the its weight and drag.
You can't do much about the airframe in this case but anything that smooths the airflow will help (as long as it doesn't add any weight!)
Weight is the real key to endurance. Every gram you can save can be transferred to a bigger battery without needing any more power to carry it.

Flying at the most efficient flying speed (in terms of power) will be quite close to the stall. It takes a bit of practise to maintain (too slow, you stall and waste power recovering, too fast and you just waste power!) however it soon becomes pretty boring!

Of course if you build a plane designed with the sole purpose of flying for as long as possible even at Bix 3 sort of size the limit is likely to be your endurance not the planes.

Ok, that makes sense. I'm going to build my plane out so I get the actual AUW and then start trying to prop it.

Thank you!

 

[Pierrot]

Im new to the forum too and find your post really good and instructive! Hope u r having fun with your bix3!