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Old Nov 20, 2010, 10:58 AM
Registered User
east coast
Joined Oct 2008
15 Posts
Hi

returned from my trip , looked very carefully at this yesterday ,
with all the CMP parts , airframe ,fan/motor ,retracts /struts
pilots - using a castle 80 amp esc and 6s 30c 4000 pack,reciver ,servos and
weighing everthing I get 2875 grams.
the stock unit(fan/motor) has a 1700 kv motor , this being my
first large EDF and reading through I feel like this stock setup
will not have enough power .

not looking super speed but not looking for a vastly underpowered
model

Please suggestion's are most welcome
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Old Nov 20, 2010, 01:50 PM
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Herb's Avatar
Irvine, Calif USA
Joined Feb 1999
12,159 Posts
Quote:
Originally Posted by Pied727-200 View Post
... using a castle 80 amp esc and 6s 30c 4000 pack, receiver, servos and weighing everthing I get 2875 grams....
Hi, you are quite a bit lighter than my estimate :

http://www.rcgroups.com/forums/showp...8&postcount=64

Your setup will be good for ca. 1300W which is a bit marginal on the T-45 ...

You need - as I mentioned above - a 20% headroom on the ESC to fly safely. Thus 64A x 6 x 3.5V = 1340W.

The Hawk / T-45 has a small thin wing with a relatively high wingloading no matter what batts you use ... it will not like flying too slow, it's not really a glider wing. For speed and acceleration you will generally need some half-decent power ...
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Old Nov 20, 2010, 01:55 PM
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Irvine, Calif USA
Joined Feb 1999
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Quote:
Originally Posted by jonnyspeed View Post
... I am wondering if 6s or 8s is the way to go. I wan to keep the amps down. I would rather have more flight time than max speed...
Welcome to the EDF world ... A jet needs speed and power which generally means shorter flying times - unless the setup is super-efficient. If you want long flighttimes get a glider

Having said that, you don't need to fly full throttle all the time. It is better (imo) & easiet on the batts, esc & motor to have a bit more power for takeoff & aerobatics and then throttle back a bit, than fly full bore all the time...
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Old Nov 20, 2010, 03:03 PM
Gilbert, AZ
chalmrast's Avatar
Gilbert, AZ
Joined May 2007
3,564 Posts
Quote:
Originally Posted by Pied727-200 View Post
Hi

returned from my trip , looked very carefully at this yesterday ,
with all the CMP parts , airframe ,fan/motor ,retracts /struts
pilots - using a castle 80 amp esc and 6s 30c 4000 pack,reciver ,servos and
weighing everthing I get 2875 grams.
the stock unit(fan/motor) has a 1700 kv motor , this being my
first large EDF and reading through I feel like this stock setup
will not have enough power .

not looking super speed but not looking for a vastly underpowered
model

Please suggestion's are most welcome
Pied,

If the fan you bought is indeed the Changesun unit as it appears in the CMPro photos, your kV is too low for 6S. You can either go up to 8S or get a motor with a higher kV... 1900. You should be the 1700-1800 watt range.

Last night I measured the dia of the exhaust tube at 72mm. This is the absolute lowest I would ever go but it will make for good top end speed. Testing will review how much thrust it robs though.

The good news is that today at the AZ Jet Rally I was able to procure most of the components I need for the build (servos, esc, wires, etc.)

Just need the retracts. I'm also thinking I may need an AR9000 because of the flaps, dual elevators, and rudder / steering servos. I have one in a 4 channel Kyosho Kelly that I may swap out since it's overkill for that plane.
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Old Nov 20, 2010, 04:20 PM
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east coast
Joined Oct 2008
15 Posts
Herb

thank you ,for your help. I have been flying Rc for many
years , electric almost 10 years , just new to edf
I have the HL f-4 and F-16 both 70mm and the HL
su-34 and they fly well , but this is my first kit jet
I was going to buy the fly fly Hawk - but when I saw this
and the price was so cheap , and I do see what your saying
about the high wing loading,

chalmrast : it looks like the one on there site , what
1900 kv motor would you recomend?
it better to have more power and throttle back , then
be under powered
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Old Nov 20, 2010, 06:08 PM
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Irvine, Calif USA
Joined Feb 1999
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Raining all day ... have a bit of time to get some work done on the T-45.

Waiting for the motor & fan not much else left to do.

Pictures of the balsa spar :
.
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Old Nov 20, 2010, 06:10 PM
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After gluing in the CA hinges, I added blenderm hinge tape on the bottom side for added safety & hinge gap seal.
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Old Nov 20, 2010, 06:13 PM
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Irvine, Calif USA
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The two $7 PZ pilots turned out satisfactory ... they really improve after getting rid of that bug green uniform .

.
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Last edited by Herb; Apr 06, 2011 at 11:59 AM.
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Old Nov 20, 2010, 06:27 PM
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Irvine, Calif USA
Joined Feb 1999
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I was writing down for fun and reference the specs on various EDF Hawks/T-45's (approx figures) :

E-Flite Hawk: WS=33'' WA =206sq in WT rtf 2.8 lbs price $160 (70mm)

Sapac Hawk: WS=37'' WA =279sq in WT rtf 3.7 lbs price $210 (70mm)

JetTeng Hawk: WS=43'' WA =?? sq in WT rtf 9.8 lbs price $600 (90mm)

CMP Hawk: WS=46'' WA =372 sq in WT rtf 7.1 lbs price $200 (90mm)

DS Hawk: WS=48'' WA =464 sq in WT rtf 7.5 lbs price $1150 (90mm)

Sapac Hawk: WS=52'' WA =524 sq in WT rtf 10.5 lbs price $650 (100mm)

Fox Hawk: WS=53'' WA =?? sq in WT rtf 12. lbs price $830 (110mm)

AMD Hawk: WS=55'' WA =992 sq in WT rtf 9.8 lbs price $300 (120mm)

Sapac T-45: WS=67'' WA =?? sq in WT rtf ?? lbs price $980 (JL Hawk)

All prices airframe only.

Edit: Quality often - but not always - comes at a price

.
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Last edited by Herb; Dec 30, 2011 at 12:36 PM.
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Old Nov 20, 2010, 06:33 PM
1.21 Gigawatts!
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Irvine, CA, USA
Joined Oct 2000
7,429 Posts
Herb did you add any reinforcements to the cockpit base? I am not sure if the thin plastic can hold those pilots. They might puncture through on a hard landing!

What about that balsa spar? Did you do anything to reinforce it?

Wow based on that list this CMP Hawk is a bargain!
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Old Nov 20, 2010, 06:56 PM
MFALLON's Avatar
Sapac Fl.
Joined Oct 2007
931 Posts
here is another two

Sapac 100mm

Wing Span: 51.51"

Wing Area: 3.64 SQ./FT

All Up Weight: 10-11 lbs

Wing Loading: 44-48oz SQ./FT
$649.00

1/6 scale sapac 127mm

T-45 ARF
Scale: 1/6
Wingspan:67"/1700mm
Length: 71"/1800mm

$980.00
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Last edited by MFALLON; Nov 20, 2010 at 07:07 PM.
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Old Nov 20, 2010, 07:06 PM
Gilbert, AZ
chalmrast's Avatar
Gilbert, AZ
Joined May 2007
3,564 Posts
AMD Hawk

Here's another:

AMD BAE Hawk $299.00:

Wingspan = 55.1"
Wing Area = 64sq. dm
AUW = 4300-4500g
Wing Loading = 76.9g/sq dm

http://www.rcmart.com/catalog/rc-pla...a-p-12059.html

AMD T-45 Hawk W/ 120MM Dyn-E-Max Fan 2nd Flight (4 min 24 sec)
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Old Nov 21, 2010, 01:15 PM
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Irvine, Calif USA
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Quote:
Originally Posted by Steph280 View Post
Herb did you add any reinforcements to the cockpit base? I am not sure if the thin plastic can hold those pilots. They might puncture through on a hard landing!
The PZ pilots, besides being a really good bargain, are quite light. The whole cockpit dressing (with pilots) only added 0.9 oz

Quote:
Originally Posted by Steph280 View Post
... What about that balsa spar? Did you do anything to reinforce it? ...
I looked at the mains retract mounts again, from the other side ... there's plenty of thin ply. I was wrong. It seems they are well made, I will keep it the way it is for now. I added a thin fillet of 30min epoxy mixed with microballons to where the ply retract boxes join edges. It should be fine, I hope . It is really a well designed kit for it's price.

.
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Old Nov 21, 2010, 01:20 PM
Renegade Fun Forever!!
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Fontana, California, United States
Joined Jul 2004
27,297 Posts
I agree Herb I went in with hysol around all the wheel well boxes but didn't think it really needed any beefing up.
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Old Nov 21, 2010, 05:38 PM
speedin n da weeds :)
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USA, AZ, Glendale
Joined Feb 2008
595 Posts
Any flight reports yet??

BTW whats hysol??
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