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Old Dec 29, 2012, 08:18 PM
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they supposedly have a one piece rotor coming out. perhaps you can inquire as to when you can get one (or two).

Rich
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Old Dec 29, 2012, 08:27 PM
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United States, FL, North Port
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Quote:
Originally Posted by Odysis View Post
You can weigh them. I can't remember the numbers, but the CS12 thread has a lot of discussion about the weak rotors.

Given your ability to pop out a mould in about 3.8seconds, could you just cast a quicky and make some carbon blades?
These rotors are the lighter (weaker) rotors.. From HK

I thought about a carbon rotor, but that is one thing that requires more work than i'm interested in doing.. to much match and smarts involved in making something that spins at 40k+ rpm's
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Old Dec 29, 2012, 08:28 PM
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Quote:
Originally Posted by LuvEvolution7 View Post
they supposedly have a one piece rotor coming out. perhaps you can inquire as to when you can get one (or two).

Rich
Yea I have been waiting and watching for when that happens, no one who really knows has said if it will be a direct replacement for the CS 90 12 blade rotor though.. Either way, i've found a replacement rotor stateside, hopefully i'll have it by weeks end.
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Old Dec 29, 2012, 08:43 PM
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Today's work started out with rough cutting out the exhaust tube outlets:



Then I finish sanded those to size/shape.


Then I made up the EDF mounting tabs. Epoxied those into place and mounted the EDF units.. its starting to get heavy now!



Then I started working on the battery and steering servo mount plates. First up I made the ply blank for the battery mounts. You'll see the corners have been cut out, these help locate the aft end of the battery plate side to side.


Then the mounts for this were cut from 1" aluminum angle. one piece of angle was notched to fit around the nose gear and bolted to the nose gear bulkhead. The other end was bolted to the backside of the forward carry-through spar. This strengthened that carry through spray up allot, so it was worth the time to do.


Test fit the plate:


Initial battery positioning thoughts:




Then my buddy Tom came over and we made a thrust tube...


Then we remounted the fan unit and attached the thrust tube to the edf unit:




Suggestion from you guys in the know.. You see I have my ESC inside the thrust tube. Due to its weight, it hangs down into the thrust efflux until the power is applied, then it kind of "floats" there. I have gotten it all bundled together as tightly as possible, but it still does the above. Would it be best to leave it like this, or just relocate the ESC outside of the thrust tube?

Then the steering servo hole in the battery plate was cut out and the mounting holes for the battery plate mount bolts drilled. the aluminum angle was also tapped as well for the bolts, and the batteries mocked up into position:



We also did a little tuft test to see what the air was doing over the bat tail area. It doesn't really tell us much (because its only one fan unit operating), except that the air isn't really swirling (rotating) much (if any). It gives a idea of the sound this monster will have though:

http://smg.photobucket.com/albums/v4...84B9F4D33C.mp4
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Old Dec 29, 2012, 09:26 PM
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it's fine in the tube. anything above 90mm is fine behind the motor. I would try and keep it as centered as possible though. most make a U shaped bracket that attaches to the stator section/center hub and that holds the ESC centered.

Rich
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Old Dec 29, 2012, 09:29 PM
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Alright, sounds good. Maybe I can make up some Zip-Tie support bracket thing for it
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Old Dec 29, 2012, 09:31 PM
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yup, that'll work.
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Old Dec 29, 2012, 09:32 PM
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I've seen some that are simply two plastic bars glued to the center hub and then the ESC is zip tied to the bars. simple and it works.
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Old Dec 29, 2012, 09:58 PM
DELTAS RULE
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man its looking awesome!
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Old Dec 29, 2012, 10:13 PM
ich bauen groß modell flugzeug
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its Phsycadellic Man!
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Old Dec 29, 2012, 10:16 PM
ich bauen groß modell flugzeug
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Quote:
Originally Posted by invertmast View Post
Those blades as supposedly weaker than the blade from another company. If it comes down to it, i'll order a new rotor from HK, but after this one had a blade snap just by tightening up the bolt, come tax time I'll probably end up going with a pair of Jet-Fan 90's
you probably got one of the bad batch then my CS-90 from HK's Rotor is Fine! (running 5-6s)
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Old Dec 30, 2012, 01:24 AM
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upland CA
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You do not want the esc to just flop in the duct..put a stick down each side of the motor tube then zip tie the esc to them as you have posted above..if it moves around it can break a lead/wire off//but then I dont like to put them in the duct anyway..but that is me
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Old Dec 30, 2012, 05:41 AM
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Lake Charles, Louisiana
Joined Jun 2009
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Quote:
Suggestion from you guys in the know.. You see I have my ESC inside the thrust tube. Due to its weight, it hangs down into the thrust efflux until the power is applied, then it kind of "floats" there. I have gotten it all bundled together as tightly as possible, but it still does the above. Would it be best to leave it like this, or just relocate the ESC outside of the thrust tube?
I like to strip off the heat shrink and also remove the heat sink. Really lightens up the ESC.
You don't want it flopping around though, like turbo said, it will eventually break a wire. Use glue, zip ties, paste or bubble gum to attach a carbon rod or bamboo skewer (or 2) to the motor housing and zip tie the ESC to it.

It's also best if you can hang the ESC on edge instead of flat like you have it in the pics. It won't flop up & down as much.


...looking good, won't be long now.
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Old Dec 30, 2012, 06:12 PM
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3.5 Degree Negative Thrust Diflection...

Tom,

3.5 degrees should work fine. The B2's rectangular to cylinder then back to rectangular exhaust issues forced Chris Gold
to place a curved thrust diflector at the furthest most rearward point in the exhaust "trough". This loaded the airframe with
excellent flight results.

With the current amount of vertical space remaining above the current exit you can move outlet vertically to accommodate
additional diflection if required.

In our B-47's we are bifurcating the inboard nacelle and have a Jeti 300 sitting in the vertical stator blade the Dynamax is
mounted to. The entire blade and edf are removable from the pylon. This places the esc immediately behind the motor and
high velocity of the edf.

I am wondering what the thickness of your esc is and if it could be placed inline behind the motor to memic a vertical stator.
A side benefit to this is the axial flow is disrupted symetrically with the esc as a stator. You could move the position fore &
aft to see if doing so reduces axial even further...

We have considerably higher amps than you are dealing with and resulting temperature. This in my opinion negates your
concern for temp at the same time it helps straighten out the post fan flow....
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Last edited by FliteMetal; Dec 30, 2012 at 07:58 PM. Reason: Graphic Image
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Old Dec 31, 2012, 12:52 AM
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United States, OH, Dayton
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This is for you Thomas!
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