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Old Aug 14, 2012, 10:25 PM
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Is there a way to calculate thrust or do i need to have the plane attached to some kind og scale to get that measurement
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Old Aug 14, 2012, 10:34 PM
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Ispintechno's Avatar
London, ON Canada
Joined Nov 2009
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Quote:
Originally Posted by M3ATpl0w View Post
Here is a link to the known test results...

http://www.rcgroups.com/forums/showthread.php?t=1601868

I think Ispintechno is right about your esc...

Turnigy L2855 – 2800KV
4S 4000 40C
Vm 14.36
Ap 63.47
Wp 950.0
Thrust(Kg) 1.6
g/w: 1.67

Perhaps a 2300kv motor would be safe for the exceed ESC.
I think I saw a video on youtube with a de havilland vampire 70mm EDF on 4S 2300kv CS10 and it flew pretty darn well.
Seems to me 2300kv with a CS10 would be comparable to a 2800kv 5 blade rotor like our stock set-ups. Be around the same amps/watts/efflux speed but get the sound your after.
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Old Aug 14, 2012, 10:41 PM
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Ispintechno's Avatar
London, ON Canada
Joined Nov 2009
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Quote:
Originally Posted by xfatdannx View Post
Is there a way to calculate thrust or do i need to have the plane attached to some kind og scale to get that measurement
I've only seen video on scales, like the scale on it's side with the nose of the airplane against it. However that way would probably lose some thrust to friction due to the landing gear.

Maybe scoop out some Styrofoam with a nose shape indent, scale on the ground, jet straight up and down nose first on the scale in the styrofoam (to not compress or damage nose tip), tear scale to zero and throttle up!

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Old Aug 15, 2012, 07:20 AM
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i remember someone asking about using the rudder as a kind of air brake...never even thought it was a real thing just something they wanted to try...check this out..





They really do that...
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Old Aug 15, 2012, 08:52 AM
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Quote:
Originally Posted by Ispintechno View Post
I think you're going to need a new ESC for that motor and fan, the stock exceed ESC is only 50amps I think. I'm in the same boat, going to try a 2800kv motor with the CS fan. The stock motor and fan pulls around 41 amps as is, with a CS10 load at around the same KV I suspect it might surpass 60amps on high timing.

The only way to know for sure I guess is the ole' bench test with a watt meter, but I imagine CS10 and 2800kv on 4S will cook the exceed ESC.
I'm going to try a Turnigy plush 60amp ESC, if it's over taxed I`ll grab a 80 amp one eventially. For a few bucks they come with a programming card that is super easy to change the settings without fiddling with transmitter, from ESC timing to what kind of song the airplane starts up with when you plug in the battery lol
Thanks to those that responded. I have a Turnigy 80 amp ESC still in the wrapper waiting for another plane. I'll give that a try and see what happens. Maybe someone in my club has a programming card I can use to check and set the timing on this ESC. That way I won't have to wait for an order from HK.

Also. On the subject of testing. I tested the stock fan against the CS10 with Turnigy 2800kv motor by setting the plane on the bench with the noise pointing at a small scale against the waill. This seemed to produce some reasonable numbers for comparing the two. I expected a small to moderate increase with the new setup but the difference was very small. I don't think the limiting factor was the battery so I'm thinking ESC or ESC timing. Since the ESC did not heat up noticably I'm leaning toward timing.
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Old Aug 15, 2012, 03:31 PM
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ok so i got almost everything done on my plane...a few small things that i was at least able to set on the plane while on the scale. Came out to 1451g. What do you guys think? Running on Bl15 3200kv w/ eflite dv fan on 4s 3300mah 35c. Think i should do okay? Kinda scared of the weight, i didn't put any ordinances or gear door. I think it will be ready to maiden this weekend if weather cooperates.

p.s. 80 amp esc so i don't THINK that will be an issue...i could be wrong though!
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Old Aug 15, 2012, 05:49 PM
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If the CG is right Fly it!
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Old Aug 15, 2012, 07:33 PM
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London, ON Canada
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Quote:
Originally Posted by MERLIN V16 View Post
If the CG is right Fly it!
Heck ya! And vid or it didn't happen!

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Old Aug 15, 2012, 08:32 PM
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Quote:
Originally Posted by carlcorn View Post
Thanks to those that responded. I have a Turnigy 80 amp ESC still in the wrapper waiting for another plane. I'll give that a try and see what happens. Maybe someone in my club has a programming card I can use to check and set the timing on this ESC. That way I won't have to wait for an order from HK.

Also. On the subject of testing. I tested the stock fan against the CS10 with Turnigy 2800kv motor by setting the plane on the bench with the noise pointing at a small scale against the waill. This seemed to produce some reasonable numbers for comparing the two. I expected a small to moderate increase with the new setup but the difference was very small. I don't think the limiting factor was the battery so I'm thinking ESC or ESC timing. Since the ESC did not heat up noticably I'm leaning toward timing.
What battery did you use (mah and C rating) for your test and what was your voltage sag at? How many amps did it pull? I've got this combo on order and from what I've read the 4S setup demands a lot of power and I'm not exactly sure what C rating and mah size battery will be needed to not eat up batteries.
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Old Aug 16, 2012, 01:15 AM
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xfatdannx's Avatar
United States, NE, Omaha
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Quote:
Originally Posted by Ispintechno View Post
Heck ya! And vid or it didn't happen!

It might not "happen" then haha. I don't have a decent camera. I will see if i can borrow my moms flip. hoping i can have someone there to film or at the least photograph.
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Old Aug 16, 2012, 08:18 AM
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Quote:
Originally Posted by AirChime View Post
What battery did you use (mah and C rating) for your test and what was your voltage sag at? How many amps did it pull? I've got this combo on order and from what I've read the 4S setup demands a lot of power and I'm not exactly sure what C rating and mah size battery will be needed to not eat up batteries.
Unfortunately I don't have a proper meeter to measure amps or voltage. Something I will be ordering soon. I tried with a 4S 2200mAh 30C and it seemed to run OK. I also tried with a 4S 3000mAh 30C and it ran essentiall the same (same sound and thrust). That is why I want to try a different timing setting on the ESC. It will be a week or more before I can try again. I may order a proper watt meeter and ESC programmer to see if I can get more from this setup. This seems to be what I'll need to work with power systems like this. From what others are saying this fan/motor combo may work well on 5 or 6 cell packs. Unfortunately I don't have that option at the moment.
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Old Aug 16, 2012, 10:29 AM
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I will have Numbers for the Stock setup using a 3300 40C 4S with an Eagle tree Data logger as soon as my friend sends them. Turns out it is faster than my Micro Corsair.
MERLIN
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Old Aug 16, 2012, 03:26 PM
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Eagle Tree Data

Totally stock Plane with a 4S 40C 4S. Fixed gear hanging in the breeze.
MERLIN
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Old Aug 16, 2012, 04:26 PM
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Merlin,
Thanks for posting. I purchased this jet a couple of weeks ago and it is resting nicely just waiting for it's maiden. I also have stock set up as I wanted to see how it flys before replacing items and I have plenty of the same batteries on hand that you used. Those numbers seem fine to me. But I'm a prop warbird pilot just getting introduced to jets. So what do I know? As I don't have an asphalt runway near by I will be hand launching on a great grass field. Hope it goes well Any one with help on how to hand launch this bird will be appreciated. Is it similar to launch as the PZ-51 etc.
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Old Aug 16, 2012, 04:38 PM
Progress with the process...
M3ATpl0w's Avatar
NE Alabama
Joined Feb 2011
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Quote:
Originally Posted by MERLIN V16 View Post
Totally stock Plane with a 4S 40C 4S. Fixed gear hanging in the breeze.
MERLIN
I think with some thrust tubes you could pick that # up quite a bit. After discussing this briefly with 3rd-dem back a few pages, I broke my kit out and carefully measured my exhaust. Both are quite elliptical and together add up to 101% FSA. Had to delay my build a few weeks, so Im having to get my jetfix via videos and these forums.
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