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Old Feb 27, 2011, 03:43 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Quote:
Originally Posted by Air Head View Post
How much clearance do I want when I trim the rotor?

On my new one, the motor isn`t exactly centered. So, on one side the gap is just less than 1/16" and on the other side it`s aprox 1/32". It shows no signs of rubbing on the 1/32" side.
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Old Feb 27, 2011, 03:44 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
7,724 Posts
Quote:
Originally Posted by ca_fingers View Post
lee, what is the diameter of the spinner on the 4.5" fan. thanks

The OD on the 4.5" spinner is 1 13/16", but the Turbax center hub is larger than that, aprox 2".
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Old Feb 27, 2011, 03:47 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
7,724 Posts
Just go back from flying my Falcon with the new fan/nacelle. It kicks ass. The thrust line is set exactly in line with the Falcon`s motor mounting plate and it was fine. When I get a calm day I may need to shim the back end up slightly, but as far as I could tell in the windy/gusty conditions today there is no diff between power on and power off.
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Old Feb 27, 2011, 03:58 PM
Lee Liddle
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Carrollton, Tx
Joined Dec 2006
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Motor Temp News......Good News

I finaly found my infrared temp sensor. That`s a good thing.

The air temp today was 75 F. After a 3 min powered flight and one low powered circut to land, I carried the plane back to the pits motor off, no cool down other than what it got during the flight.

Aprox 30 sec after landing the back of the case temp was 50 C. For about 30 sec to one min the tem continued to rise and reached a peak of 62 C. By that time I had removed the nacelle and efflux tube so that I could get a reading on the windings. They were at 73 C at the same time the case was at 62 C. Then both the windings and the case began to cool.

I think that if I had done a 1 min cool down run, as is my habit, the windings would have seasily stayed below 65 C and the case below 55 C, those are guestimates of course.

I say, put this sucker in a full Turbax on 12s, with the stand off and it will hold up at 6kw+ with careful operation.
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Old Feb 27, 2011, 04:19 PM
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Joined Jan 2005
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I have a standoff and mounted a motor in the fan

I have two of these setups. One the motor mounted inside the fan housing, the other on the standoff.

Any thoughts on the internal mounted motor? It sounds like it should work out.

I am making the fan easy to remove so I can do any work on it if need be. I can go both ways.

I have the thickness of two playing cards all around on my trimmed down rotor - I am thinking it may be a bit tight.

Time to start a build thread. I am almost ready to glue the fuse together.
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Last edited by Air Head; Feb 27, 2011 at 05:17 PM.
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Old Feb 28, 2011, 12:38 PM
PH.D in Scratchbuilding
Denmark, Region Zealand, Holbaek
Joined Sep 2005
325 Posts
A little video of the static test.....

søndagens flyvning 003 (0 min 46 sec)
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Old Feb 28, 2011, 12:42 PM
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Have you ever seen a fan let loose?

Looks dangerous from here.

I take it that you have never seen a fan come apart. With the power levels this operates at I suggest a bit of caution. Looking straight into the intake a few inches away.... Keep your fingers crossed that you don't have a problem.

Good luck - it seems that its working.

I just loaded up the batteries in the nose to get a look at the fit. I may have underestimated the size a bit. I think I may mount the receiver behind the exhuast ducting, I planned to mount it behind the battery but I think after the intake ducting is figured out I wont have any room up front.

I am tossing the idea around to cut the front of the fueselage and add a few inches.
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Last edited by Air Head; Feb 28, 2011 at 12:58 PM.
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Old Feb 28, 2011, 01:19 PM
PH.D in Scratchbuilding
Denmark, Region Zealand, Holbaek
Joined Sep 2005
325 Posts
no one is looking straight into the intake...... thats the rear end


Your design looks interesting.....
where do you plan to put your intake?? The intake needed on this fan will give a lot of drag for a glider...... would be cool to make some intake hatches that open when the fan is powered up and closes when power thottle goes to zero....
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Old Feb 28, 2011, 02:13 PM
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"no one is looking straight into the intake"

Ill say it again - I take it you have not had a fan come apart.

A fan failure is similar to a hand grenade - it "EXPLODES" - It seems to me that you could not pick a riskier place to sit.

__________________________________________________ _______________

My intake would be infront of the fan behind the batteries - right about where GI Joe would be sitting. There will be a big hole where his head would be for the intake.

This is a prototype, and I have already stumbled quite a bit with this build. I want to try to make this one work but I have a lot of changes to make on the next one. There has been a lot of trial and error, and error, and error.

The idea of an intake that can close up I have been tossing around and don't see why that could not be incorporated. I think on this build ill just leave it open but on the next one I think I may try to figure it out. I am just about ready to cut my plug and insert a few inches. I wanted to get a scale like setup and have the ducting behind where the pilot would sit. This got a little small and there is no room for it on this build.
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Old Feb 28, 2011, 02:30 PM
Keith Thomas
United States, NM, Portales
Joined Feb 2010
923 Posts
Nice looking bird Air Head. Is the exhaust coming out the side going to have any effect on forward thrust? To me, it looks like it may suffer unless you are planning on making some type of “S” turn. I hope all works for you.
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Old Feb 28, 2011, 02:50 PM
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Is the exhaust coming out the side going to have any effect on forward thrust?

Id imagine it will but how much I dont know. I keep changing things around and have not glued anything together yet. I think I should rig something up and test it on the bench to see. I could go straight out the bottom of the fuse I think - and keep everything straight. Perhaps that is the way to go.

I am almost ready to make a second fuselage with a lot of changes.

Ill start a build thread and keep from cluttering Lees $100.00 Fan Setup Thread.
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Old Feb 28, 2011, 03:07 PM
PH.D in Scratchbuilding
Denmark, Region Zealand, Holbaek
Joined Sep 2005
325 Posts
I have seen fans come appart... explode. I have seen models cut open by a loose blade. Sure it's dangerious...... But if a blade should come loose in this model, it will stay inside.
If going anywhere it will come straight out to the side through fanhousing and carbon/glass skin... The fan sits right under the tailfin. If anything should be any means go forward it will stay inside the duct.

So no... I'm not worried sitting where I at.....

----------------------------------------------

Anyway we all know it's not kids toy...... this is deadly "grown-up toys" which have made a lot of people hurt.
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Old Feb 28, 2011, 03:09 PM
PH.D in Scratchbuilding
Denmark, Region Zealand, Holbaek
Joined Sep 2005
325 Posts
Looking forward to se the changes you have made to the second fuselage.... please drop a link when the build thread is started....
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Old Feb 28, 2011, 08:11 PM
Been there , Crashed that
Joined Mar 2010
104 Posts
hi all , i ordered 2 fans and 2 motors the other day . 4 " fan with 1100kv motor for the f 18 and a 4.5" with 880kv for the mirage . ducting for the mirage is almost ready to mold . im going packing tape/ lost foam method as its only a one off job. what weight of glass do you use for your ducts? ive got a bunch of left over 6 oz. cloth that i could use. is one layer enough or should i go 2 layers of the 6 oz.? using epoxy lam. resin if that makes any difference. thanks
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Old Mar 01, 2011, 02:55 AM
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Molde, Norway
Joined Jan 2001
2,430 Posts
Nice wood work!

I would go with 2 layers of 6 oz. One layer will be a bit thin and will most likely need carbon tow reinforcement to prevent collapse.
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