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Old Nov 19, 2011, 02:23 PM
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Guys...PLEASE read the NitroPlanes T-45 thread...If the published CG of the HK Hawk is the same as the published CG in the T-45 manual you WILL crash!!!...A good starting point for the T-45 CG is 110mm measured from the leading edge of the wing where the wing meets the fuselage...The published CG in the T-45 manual is about 130/135mm...The suggested way to calculate the CG in the T-45 manual is overly complicated---CMP suggests that you measure out 280mm from the center seam of the fuselage toward the wing tip and then 60-65mm from the leading edge of the wing from the 280mm point...

Again, read the T-45 thread and Herb's build log or you could repeat some of the mistakes that have already been discovered...

Kevin
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Old Nov 19, 2011, 02:39 PM
"Take Off" eh!
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Canada, ON, Beeton
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this sounds allll to familiar.

Thanks for the heads up Kev

Trev
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Old Nov 19, 2011, 02:44 PM
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again if he had set the CG according to manual he should have been tailheavy .. not noseheavy
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Old Nov 19, 2011, 03:04 PM
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Quote:
Originally Posted by pavcon View Post
again if he had set the CG according to manual he should have been tailheavy .. not noseheavy
He moved the batts back to get the REARWARD placed CG...He was tail heavy as described by the snap/stall that he experienced...I know you just misread his post as he said he had to place his batts all of the way back AND add lead to the tail to get the plane to balance @ the published CG...The plane appeared to be nose heavy if you go by the published CG...He found out that the published CG is wrong when he attempted to fly it...Re-read his post...


[Good news is I got mine delivered last Monday and it is one beautiful model..
Bad news is she had her maiden today and didn't have enough power, and too tail heavy.. Got 3ft of the deck, pitched up and rolled onto the wing.. Repairable but upsetting just the same..
Setup was a jetfan90 with het motor on 6s, 5000mah no where near the power needed, thrust tests before the flight kind of told me that but since it was a bungee lauch i figured give it ago..so I'm gonna have to build a thrust stand to test what output I'm getting.. If anyone knows of a good build thread for one let me know.
I followed the manuals cog position which meant putting the battery as far back as I could, and all the electrics far back between the ducts and yet still had to add a lot of lead to the tail to get her to balance on the stand as per manual but flight characteristics point to her being tail heavy?
When you get your models could you let me know if you think the manuals cog is correct as she seems to be way to nose heavy with components in normal positions without landing gear..
Anyway on with the repairs...
I too wanted to put my p20 in this but conferring with my fellow flight buddies I don't think a p20 will have enough guts..]




Kevin
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Last edited by Kevin Greene; Nov 19, 2011 at 03:09 PM.
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Old Nov 19, 2011, 03:23 PM
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oh.. sorry..
still I havent got an answer for the motor. for a 6s setup I would have used the 2100kv motor.. and have plenty of power..
the 1680kv should have been enough to fly .. can't really see where is the lack of power.

unless you have the 36mm series which again you should have been around the 2000kv range
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Old Nov 19, 2011, 03:38 PM
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btw guys is it a cmpro or JTM ? ?
Jet Teng Bae Hawk with Wren 44 (4 min 46 sec)
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Old Nov 19, 2011, 04:00 PM
Fly now crash later
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Canada, ON, Newmarket
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Changesun 12 blade 90mm. Herb ordered it over on the T-45 thread, I'm going to watch and see what he thinks of it. They want $45.00 for.

http://www.x-flight.com.hk/index.php...20Expiried!&s=
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Old Nov 19, 2011, 04:15 PM
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Originally Posted by davecrash View Post
Changesun 12 blade 90mm. Herb ordered it over on the T-45 thread, I'm going to watch and see what he thinks of it. They want $45.00 for.

http://www.x-flight.com.hk/index.php...20Expiried!&s=
we need to know how much abuse they take and if just the first batches come balanced..
and what's the amp draw on which kv.. we literally have no feedback so I wouldn't risk it.
you do the tests for me I'm going STU
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Old Nov 19, 2011, 05:07 PM
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correct registration no and all flying tail deffo jtm
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Old Nov 19, 2011, 06:02 PM
Fly now crash later
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Canada, ON, Newmarket
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Quote:
Originally Posted by Kevin Greene View Post
He moved the batts back to get the REARWARD placed CG...He was tail heavy as described by the snap/stall that he experienced...I know you just misread his post as he said he had to place his batts all of the way back AND add lead to the tail to get the plane to balance @ the published CG...The plane appeared to be nose heavy if you go by the published CG...He found out that the published CG is wrong when he attempted to fly it...Re-read his post...

Kevin
What was your setup?
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Old Nov 19, 2011, 06:50 PM
Bypass Ratio = Infinity
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Quote:
Originally Posted by pavcon View Post
we need to know how much abuse they take and if just the first batches come balanced..
and what's the amp draw on which kv.. we literally have no feedback so I wouldn't risk it.
you do the tests for me I'm going STU
Umm...Flip Flop has flown one of these already so numbers exist for a HET 700-60 1485Kv motor on 8s. Its over on the 90mm CS fan thread.

http://www.rcgroups.com/forums/showthread.php?t=1520120
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Old Nov 20, 2011, 05:26 AM
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For the motor I went with the het-700-68-1200 on Jetfans recomendation.. I wanted to use my existing 6s 5000 packs..
Would you think the KV was too low?
I could use either my 2x 4s 3200 packs in series for 8s or 2x 5s 3000 packs for 10s I have both available..
The esc im using is the Turnigy kforce 150a but looking at the speck it is only for 2-6 cells?

http://www.hobbyking.com/hobbyking/s...ess%5FESC.html
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Old Nov 20, 2011, 06:13 AM
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that is a jet tang there almost 1k Aud great plane but

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Old Nov 20, 2011, 06:22 AM
Bypass Ratio = Infinity
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http://www.rcgroups.com/forums/showt...1504718&page=2

Yes 1200 is too low on 6s. Per the JetFan thread a 1200Kv motor is recommended for a 10s setup. You need an 1800-2000Kv motor according to their testing. That thread actually has very nice lists of motor type, cell count, thrust, and other data points that are very helpful for picking the right motor for a given application.
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Old Nov 20, 2011, 06:38 AM
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Denmark, Nordjylland, Gistrup
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Quote:
Originally Posted by ghettotige View Post
For the motor I went with the het-700-68-1200 on Jetfans recomendation.. I wanted to use my existing 6s 5000 packs..
Would you think the KV was too low?
I could use either my 2x 4s 3200 packs in series for 8s or 2x 5s 3000 packs for 10s I have both available..
The esc im using is the Turnigy kforce 150a but looking at the speck it is only for 2-6 cells?

http://www.hobbyking.com/hobbyking/s...ess%5FESC.html
That was way to low, take a look here under news/ neue messungen: http://www.ejets.at/
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