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Old Jan 27, 2013, 03:41 PM
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My next FPV build: wild questions

Hi all,

I'm starting my next FPV build. Learned a lot from my current quad and FPV setup but now is the time to try something new.

I really love the Vtail design and shape by DiaLFonZo & Bledi so it would be great if that could be my new frame. First some research. Maybe my questions seem odd or totally unrelated but hey, that's how my mind works

1. Keeping all parts (motors, ESC, props, LiPo, etc) the same and under similar weather conditions, is the VTAIL more or less power efficient than a "normal" X4 quad configuration?

2. Out of the box thinking: using a VTAIL quad and one or two additional props (or EDF's) pointing straight back for horizontal thrust, would this increase efficiency?

I mean the four VTAIL props would then act more like wings and rotate at a lower more efficient RPM and the two additional props are also used more efficient and provide the speed forward. These can be switched on/off on an Aux channel and run on a separate LiPo.

3. I'm currently using a Spektrum TM1000 for telemetry, it can only monitor the RPM of one motor. Is there some way to monitor the RPM on all four motors (either by using the TM1000 or something else) ?

4. I'd like to run two 3S LiPo's in parallel however the cell voltages are not exactly the same. LiPo A) 4.15v / 4.20v / 4.16v and LiPo B) 4.16v / 4.13v / 4.20v
Wat is the maximum voltage difference between LiPo cells you would allow when connecting two LiPo batteries in parallel?

5. I would like to re-use my DJI 2212/920KV motors and 10-5" Graupner e-props on the VTAIL, wise choice or better (more power efficient) solutions?

Yup, key is power efficiency as my goal is a 6-mile FPV roundtrip based on something light and portable but still able to carry the GoPro (Hero3), all the FPV stuff

Looking forward to your replies, ideas and maybe some out of the box stuff

Cobalt
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Old Jan 27, 2013, 11:41 PM
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MayMayDay's Avatar
Canada, BC, Vancouver
Joined Mar 2012
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Quote:
Originally Posted by Cobalt3000 View Post
Hi all,

4. I'd like to run two 3S LiPo's in parallel however the cell voltages are not exactly the same. LiPo A) 4.15v / 4.20v / 4.16v and LiPo B) 4.16v / 4.13v / 4.20v
Wat is the maximum voltage difference between LiPo cells you would allow when connecting two LiPo batteries in parallel?

Cobalt
I'm more worried about the varying cell voltages per battery, let alone whether you can run them in parallel (which you can if they have the same specs). When was the last time you balanced those suckers?
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Old Jan 28, 2013, 05:24 AM
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Actually I always balance charge them. The first LiPo does show 4.20v for each cell when my charger says "full" (takes about 70 mins at 1C). The values in my original post are from a separate voltage meter several hours after charging finished.

The second LiPo never got to full because the charger doesn't seem to get one cell up to the same level, so it stops when the timer hits the two hour charge limit.
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Old Jan 28, 2013, 05:51 AM
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Canada, NS, Halifax
Joined Feb 2010
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Sounds like your lipos are bad. I wouldn't use them in parallel.

As to the rest of your questions it all sounds complex and heavy to be honest.

The vtail is probably less efficient as the front motors do more lifting than the rear as the rear are more setup for yaw control with the tilt so not producing as much pure vertical lift.
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