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Jun 13, 2019, 07:26 PM
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seng30904's Avatar
Iím not sure of itís rated specs, however, motor temps are usually a pretty good indicator. Check them often when upping the prop size. I think the 9 inch prop sizes are a better choice on 4s, and as you stated, 8 inch sizes for 5s
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Jun 14, 2019, 11:19 AM
Julian T
Quote:
Originally Posted by johnnyrocco123
I ran the motor on this setup and got 74.95 amps static. I was using a F3A 5000mah 35c 5s pack.

Seeing that the proposed prop is square, I can't see it pulling less in the air. Or at least not much


So the important question is, what is this stock motor rated for? I can't find any info on it.
I haven't seen any specs either. According to my tests, my setup with 8x8 APCE, 5s (2700 Graphene), stock motor and HW ESC pulled 70A giving 1260 watts into the ESC and turned at 14,700 RPM. (That equates to a theoretical pitch speed of about 111 mph and thrust of about 4.5 lbs.) That gives a very low theoretical efficiency of 43% based on a calculated power at the prop of 544 watts. However, I have found calculated efficiency on square props static is nearly always abysmal and this is not out of line with other similar tests. I am pretty sure my setup does unload in the air in spite of the square prop.

If you can measure watts instead of or as well as amps, and rpm then a rough efficiency calculation can be made.

So far mine has held up fine - I flew it today - and motor came down relatively cool, about 45 C at a guess. It is certainly a LOT cooler than the setup in my RB gets on 6s. I tend to fly flat out for about 2 minutes and that was enough to drop the pack to ~ 3.75v / cell resting. That would imply about 60A in the air if the pack capacity is still 2700 - if it's less then the amps are correspondingly less. I can't check how much the packs take back to get to full charge as my mate has taken the packs home for his own use (it's his packs!).

But like seng says, motor temp is golden to knowing if you are about to fry it.
Jun 14, 2019, 04:46 PM
You down with EPP?
johnnyrocco123's Avatar
Quote:
Originally Posted by juliant
I haven't seen any specs either. According to my tests, my setup with 8x8 APCE, 5s (2700 Graphene), stock motor and HW ESC pulled 70A giving 1260 watts into the ESC and turned at 14,700 RPM. (That equates to a theoretical pitch speed of about 111 mph and thrust of about 4.5 lbs.) That gives a very low theoretical efficiency of 43% based on a calculated power at the prop of 544 watts. However, I have found calculated efficiency on square props static is nearly always abysmal and this is not out of line with other similar tests. I am pretty sure my setup does unload in the air in spite of the square prop.

If you can measure watts instead of or as well as amps, and rpm then a rough efficiency calculation can be made.

So far mine has held up fine - I flew it today - and motor came down relatively cool, about 45 C at a guess. It is certainly a LOT cooler than the setup in my RB gets on 6s. I tend to fly flat out for about 2 minutes and that was enough to drop the pack to ~ 3.75v / cell resting. That would imply about 60A in the air if the pack capacity is still 2700 - if it's less then the amps are correspondingly less. I can't check how much the packs take back to get to full charge as my mate has taken the packs home for his own use (it's his packs!).

But like seng says, motor temp is golden to knowing if you are about to fry it.
Well it is hot as hell here in Texas. But, I am still going to try it. Maybe around 9am before it gets scorching hot.
Jun 14, 2019, 05:17 PM
You down with EPP?
johnnyrocco123's Avatar
Going to stick with the AP 8x8e. Bringing a 4s 3300 65c and a 5s 2700 70c
Jun 15, 2019, 12:36 AM
Registered User
That looks cool in all white. Is that just with included stickers?
Jun 15, 2019, 01:17 AM
Julian T
Quote:
Originally Posted by johnnyrocco123
Well it is hot as hell here in Texas. But, I am still going to try it. Maybe around 9am before it gets scorching hot.
Ah yes, I forgot that! It will make a difference.
Jun 15, 2019, 12:22 PM
You down with EPP?
johnnyrocco123's Avatar
Quote:
Originally Posted by Herrsavage
That looks cool in all white. Is that just with included stickers?
Most of the stickers came with the kit. I added the EF stickers from my Pantera

BTW, I didn't end up using the majority of the stickers. If you used them all, it looks painted. I would recommend the white scheme. So many possibilities. And it is priced quite well. Even for Multiplex . lol
Jun 16, 2019, 12:20 PM
Registered User
Thanks for the info. That does look good in white with the stickers.

I was wondering - I have a bunch of Parkzone T-28 props(9.5x7.5), AND an SK3 3542 1185kv motor. That setup in a Parkzone P-47 is pretty awesome. Well, it is with the SK3 1250kv version of the same motor. Can't be that far off... Anyway, was wondering if a setup like that would have more potential than the stock setup.. I also have F-27 motors, and an oder spare EFXtra motor. Plus the FMS 770kv motor out of the 980mm P-40.... I will be putting in a YEP 80a ESC right away.
Jun 16, 2019, 12:44 PM
You down with EPP?
johnnyrocco123's Avatar
Quote:
Originally Posted by Herrsavage
Thanks for the info. That does look good in white with the stickers.

I was wondering - I have a bunch of Parkzone T-28 props(9.5x7.5), AND an SK3 3542 1185kv motor. That setup in a Parkzone P-47 is pretty awesome. Well, it is with the SK3 1250kv version of the same motor. Can't be that far off... Anyway, was wondering if a setup like that would have more potential than the stock setup.. I also have F-27 motors, and an oder spare EFXtra motor. Plus the FMS 770kv motor out of the 980mm P-40.... I will be putting in a YEP 80a ESC right away.
After the stock setup on 5s with 8x8, I might try my big boy inrunners. But they are so heavy. I am talking like 100-110 grams heaver than the stock motor. Then it would require a bigger battery.... ugh.

I would just try the stock motor and push it to the limit. No big loss if it sizzles. Then drop one of your others. These airframes make for great test subjects lol
Jun 16, 2019, 01:02 PM
Registered User
I flew my V900 today, and thought I had the hand launching down. Nope... Torque roll into a ground-cartwheel. Two "successful" launches which were very squirrely... I kind of hate most about the V900 -design, quality, etc.. BUT - it is really quite fast on 4S, and the big factor for me - it is VERY quiet for its speed. I reckon it is about as fast on 4S as the EFXtra on 5S - but in the spot where I was flying today, right next to a village on a quiet Sunday evening in a quaint spot next to the river, the EFXtra on 5S would have terrified pensioners and woken children...... It's a bit of a dilemma. Hope the FR isn't as loud... - AND more forgiving than the V900.
Jun 16, 2019, 01:34 PM
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john2kx's Avatar
I’ve hand tossed v900s, efxtras, FRs, and RBs for many of my club mates. The v900 has the best launch characteristics of the 4 mentioned in my opinion.

I have yet to see anyone crash a v900 during launch at my club. I feel certain the as3x helps.

Keep a eye on the vertical stab as I have witnessed fractures where stab meets fuse on a few. Changes in pitch (at speed) is a indication you have this issue.

It does fly well and is quiet. If one wants to go fast (130 mph+), I would choose a different airframe as there are other issues with the design that need upgrading as documented in the appropriate forum.

John
Jun 16, 2019, 02:04 PM
Registered User
I only have hand launch planes - including an EFXtra, EFX Racer, various warbirds, various wings, etc etc... The V900 is right up there with the hardest and most unpredictable to launch. I have no AS3X and don't want it.. I know I know - but still, I don't like gyros. I just have to figure out what tricks it requires to get it to launch right... It is very torquey. The EFX planes I could practically launch with my left hand in comparison, and if asked to touch my nose with my left hand I might poke my eye out...


Also, launching for somebody else is (very much) a different thing than launching on your own. Especially with no gyro help for the guy on the sticks...

I definitely have to up my expo way up.. On my two non-unsuccessful launches today, the squirelliness was totally different to how my other planes respond... Squirrely.
Jun 17, 2019, 03:01 AM
Julian T
Launching the FR has been a topic before. See https://www.rcgroups.com/forums/show...&postcount=443
I followed this advice and coupled with a launch condition of slight right rudder (2mm) and slight right aileron (1mm) the launch ceases to be an issue. I used to find the RB a tricky one for torqueing too but this has also tamed it to the point launches are a non event. I should add I never self launch as I am worse than useless at it.

Julian
Jun 17, 2019, 03:11 AM
Registered User
I fly exclusively solo, so have to manage it alone. I generally consider myself pretty good at it. I mean I have thousands of flights doing it with all kinds of planes. The V900 (and Sonicmodell HD 1213mm wing..) just kind of confounds me though.. Which is weird - because the first 10 flights were effortless. Then I had the blown ESC, a stall before landing, then a dodgy launch, and since then I feel kind of psyched out about it. Probably just need to think less..

The RB can be tricky - but for the most part with it I find the main issue is if you give it too little throttle. Otherwise it's not too bad I find..
Jun 17, 2019, 08:28 AM
Julian T
I think you are right that you can think yourself into failure. I always used to self launch up till around 10 years ago. Then I had a couple of bad ones and I seemed to just get worse and worse. If I were to try it now I know I would be expecting it to fail and such thoughts can be self fulfilling


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