Megabar Plug is cut
 

or this one

Air Intakes
 

Hi Eddie,
Nice project. As far as intake ducts go for our models the more volume you have in front of the engine the better. General rule is that any duct that expands in volume should not have a sidewall slope of more than 7 degrees to prevent seperation of the airflow. This means that the air in front of the turbine is moving slower than at the intake and thus has more pressure, helping the compressor a bit and countering the negative pressure effect of the exhaust venturi effect in our bypass sytems from reducing the pressure the inlet sees. Narrow inlet duct + lots of bypass = easy flameout of the engine.
Cheers,
Andre

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We started cutting the nose sections at 7:00 pm
and finished about 4 hours later.


Here is the computers ver of the nose.

Megabar Plug is cut
 

I did not get any pics of it cutting but when I
took a few when I got home.

It looks just like the drawing except it's BIG.
This plane is bigger than I thought it would be.

Megabar Plug is cut
 

btw.. the hatch fits perfect.... non of these pices
have even been sanded yet.

Eddie Weeks

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You need to start on a pocket sized model - the millibar! :p

Hi Eddie
 

What is the diameter of the inlet throat on your bypass?

You mentioned a .75 clearance around the turbine, is that correct?


TIA

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I just wrote this long post about bypasses and how
to design them....

I attached a pic that was too large, I hit the back
button and RCUniverse lost my post... :confused:

Eddie Weeks

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Eddie,

That engine looks like a JetCat, what with that nice looking purple inlet cover!!! Glad to see you finally saw the light.

DR

PURPLE INLET
 

David,


Wrong again Buzzard Breath!!! :eek: As Eddie calls it, that is a Purple Faced Pegusus.. Just like the one I got.. AMT Netherlands Pegusus HP... :D Tell everybody Merry Christmas over there.. see ya'll at Florida Jets!!!

Danno :cool:

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Hey Danno,

Imitatioin IS the most sincere form a flattery! But tell the guys at AMT that it is not the purple paint that makes the thing so damn reliable!

DR

update
 

Well its safe to say, what ever engine the Megabar will have
it will have some ass.

We spent all night trying to cut the two parts below
and every thing was going well till the cutter running
at 350in/min knocked off a large section of the fuse.
It was not a error, it was just not glued down well
enough. (my fault, long story)

We also had some problem getting the machine to cut
such a large part. There was only 0.300" to spare out
of 38".

Tonight we decided to just cut one part at a time. I made a
stack of nine 3/4 inch boards of MDF. Drilled five 5/8 holes
through the 7 inches of wood and inserted five, 1/2" all tread
rods. After gluing together, nuts were tighten to smash
the boards together a tight as possible. Later the all tread
was removed and replaced with 5/8" dowel rods..

This smaller part took 60,000 lines of G code and was finished
in 1:20 flat using a 2 inch fly cutter at 350 in/min at 5100 rpms
with a depth of cut of 0.175. Then two different finish passes
of the 1" ball endmill, 8 inchs long at 7000 rpms

The part came out perfect.

I will have some pics tomorrow after we cut the other side.

Eddie Weeks

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right tail section

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I sanded on this one for about 15 min

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they match... They are accurate to 0.001"

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Very very nice. How ya gonnna lift it when its all glued together?

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After 10 nights at the machine shop, Darren and I
are done with the Megabar plugs. They are big,
heavy, solid and accurate and are just like the
drawing. Here are a few pic, and Rocketboy
I don't know how I am going to lift it because
just the mid section plug of the left side is a job
to carry around.

Maybe I will not have to move the plugs much..

Eddie Weeks

Congrats Eddie
 

Great job.

BTW how did you get access to a 5 axis CNC? AND SurfCAM???

We are having a prototype product machined out of REN-Shape, I can only imagine how much a chunk of REN big enough to do that plug of yours.

It probabaly would weigh about the same as that wood, it is about 30 pounds per cubic foot!!

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Thanks Matt

I was on my way to buy a large chunk of Polyurethane Tooling Board from Freeman but the cost for the cheep stuff was
over $1000. The MDF wood was ~$16 for 4x8 sheet of 3/4".
And we cut it at 350 in/min. The wood is far heaver at around
~60 lbs/ft^3

A good friend of mine, Darren, who I have know for years
owns the company that has the 4th axis CNC and Surfcam.
Darren is a Master Programer in G code and just a few hours
ago he ran a 170,000 line program in 4 hours without stopping
once. (we did stop to take a few pics)

If you want I can make a MDF board for you. Any thinkness
, any size, (you pay shipping).

Eddie

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.

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This pic show how big the Megabar is.

Its 90 inchs long and takes up the whole 8 foot table.
I should be able to see it ok in the air..

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This is how the parts are going to be molded

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There are more, bigger pics and one movie click here

http://www.corpcomp.com/weeks1/mb/mb.html

Eddie Weeks

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It'll NEVER get offthe ground! It's too heavy. Ha HA ;) :D

Kool Job , Eddie.

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I like the layout but why did you make the plane so short coupled?

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Eddie, Be sure to include a handling charge for those glued up MDF stacks. Your going to need it to pay for new knees when your done.

Just Kidding - Your Dude

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sup Juice...

Terry, I have a J-79 laying around here some where.
That'll fly it.

RC_Man When I started on this plane
I wanted to lengthen the dist between
the wing and the stab, so in the first
drawings, the wing was much farther forward.
After installing the 5-6 lbs turbine, I felt it
would be tail heavy, so I moved it back a bit
and that is where it is now. The Isobar is very short
tail coupled, and everything is fine. It ouly requires
more elev movement. So to answer your question
I have no real answer.

Eddie Weeks

RE: Megabar Plug is cut
 

How do you model that compressor in SW.
I have been using SW for a couple of years now and there are some things that I have not figured out yet.
This is one of them.

Do you draw the pre-load spring a "Compressed Length"?
How do you get it to fit in the assembly?

Are you open to answering a couple of other questions on SW?

Thank you.

Regards,
Dale

RE: Megabar Plug is cut
 

So... is the MegaBar available? Kit? The web pages referred on this post no longer exist...

RE: Megabar Plug is cut
 

Contact RCU member SeanReit, he is the Megabar producer.

RE: Megabar Plug is cut
 

Eddie your still alive !!!!!  Where you been man? Get caught in a tornado or what?

Tim

RE: Megabar Plug is cut
 

Anybody have any info on either an isobar or megabar setup? I could really use manual, plans or even pictures of the internals would be very helpful. I just came into 2 isobars and 2 megabars... Although i can easily wing it, any help would be appreciated. (I also posted this in the Isobar thread) thanks