Conference vmszoo::rc

The first order of business was to decide upon a scale to build to. After 
making some measurements I decided that 1/5.25 would be perfect. Then came
the task of drawing up a side view to proper size. When I built the Jet Ranger
I used a side view I had to make an overhead. I then projected the overhead
on a sheet of paper and traced the lines when I had it blown up to the right
size. I tried that this time and noticed that it resulted in some distortions.
One of the problems with my Jet Ranger is that the side profile doessn't quite
match the side view. I think I know why now.

I decided to cheat at that point and used a copier to blow up sections of the
side view and then taped all of the sections together. That blew all my careful
scale calculations to heck and I've ended up with a scale of 1/5.5. With a side
profile to work with I started work on getting the cross sections made up. I
have to admit to having no talent in this area. If I had to draw up cross 
sections by hand this project wouldn't get done. 

To get the cross sections I took a plastic kit of the Hughs 500 and built half 
a fuselage. Working with a little bit of polyester resin at a time, I filled 
up the fuselage half so it could be cut into cross sections. I stress the 
'little bit' here because polyester resin generates heat as it cures and if 
you pour too much at a time you'll melt the plastic model. Before I cut the 
model up I mounted it on a piece of board. The board was marked up with lines 
for eash cross-section and then a reference line that ran across all of the 
divisions. Each section was labled for later identification.

Once I had all of the sections cut out on a band saw I took pictures of them. I 
took a slide shot of each section against a backdrop of graph paper. The graph
paper gives you something to focus with when you project the slides. Next I 
matched the cross sections up with the coresponding points on the side profile.
I took some file folders, marked the width of each section on the folder, and 
then projected the corresponding profile on the folder to line up with the 
marks. Trace the outline of the cross section and you're all set.

At this point I had a side profile blown up to the correct size and a set of
cross section to match the corresponding points on the side profile. Next 
installment will cover building the plug.

You might try some of the micro balloon fillet materials since they have a good
strength/weight/cutability

I have some fiberous casting agent left from my cowl making attempts. Sort of a
cross between paper mache (sp?) and plaster of paris. No shrinkage or solvents. 
I got it at an art supply store.

Must have been fun cutting the sections so as not to distort them with the 
bandsaw blade heat (but you didn't want to think about that right? ;^)

>You might try some of the micro balloon fillet materials since they have a good
>strength/weight/cutability

If you want to keep the weight down try the new micro balloons with the
"helium" - it is suppose to be 30 percent lighter with the same strength.

Bye          --+--
Kay R. Fisher  |
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RE: last few

>You might try some of the micro balloon fillet materials since they have a good
>strength/weight/cutability


    That's an interesting though but I think I'll stick with the resin. I
    know it works, its readily available at the hardware store, and does a 
    great job of supporting/protecting the plastic. It's only drawback
    (other than smell) is the heat generated during curing and that can be 
    managed by doing small layers at first. 

>Must have been fun cutting the sections so as not to distort them with the 
>bandsaw blade heat (but you didn't want to think about that right? ;^)
                                                                     
    

    I must be lucky because I've never seen any evidence of distortion
    caused by the blade heat.  I just started thinking about it and I
    don't think you could get distortion. The blade is being pulled
    downward thru the plastic and then the resin backing. That means that
    when the blade touches the plastic it's had a chance to cool down some
    what during its upward trip on the loop. Then again, the sections I've
    cut have either been 1/2" to 3/8" inch thick so maybe there's too much
    mass there to be affected. If I ever try cutting thinner sections I'll
    have to keep this in mind.

    Thanks for the info.
    
    Dan Eaton

Time to get started on the plugs. There's only three steps involved.
1. Build a big block of styrofoam.
2. Cut away anything that doesn't look like a helicopter.
2. Finish the surface as smooth as possible.

To do step one I took the side profile and traced it onto two pieces of wall
paneling I had laying around. These were then cut out and bolted together for 
a final sanding to shape. These will be the base for the left and right side
of the plug so their outline must be identical. Then I transfered the marks
showing where the cross sections where taken from the side profile onto each
side.

Now we're ready to make a mess. There's probably better stuff to use but the
hardware store had white foam cheap so that's what I bought. It came in about 
3/4" thick panels that ran around 1' x 4'.  I'd stack two sheets together and
then pin a cross section on top of the sheets. Remember that those cross 
sections where cut from the tracings made on the file folder material. Since its
really a half of a cross section, you cut two pieces of foam to come up with
the full section. Take the sheets over to your hot wire jig saw and cut them 
out. Do that for all your cross sections. Do it in a well ventilated area.
Like maybe outside on a windy day.

When I got to the part about a hot wire jig saw I had a problem. I didn't have
one. I built one by taking my portable table saw and adding a 1 x 2 vertical
to each side. The vertical sections stick up above the table surface about a
foot. Then I put a piece of 1 x 2 horizontally across table supported by the
uprights. 

A visit to the hobby shop yielded some .015" thick music wire.  I drilled a 
small hole in the table and a matching one in the cross piece. Make sure these 
holes line up at a right angle to the surface of the table. Take one end of 
the wire and wrap a few turns around a bolt. Then tread a nut onto the bolt to 
lock the wire down. Now thread the wire down thru the cross piece and the 
table. To provide tension I C-clamped the wire to a heavy metal bar so it was 
suspended underneath the table. If you did your work right the wire is square 
with the surface of the table so your cuts in the foam should be square also.

To power the beast I attached a clip lead to the bolt on top and another to the
wire where it exits underneath the table. The other ends of the clip leads got
hooked up to an old Lionel train transformer I had. Just barely turning it on 
got the wire hot enought to cut the foam. Turn it up too much and the wire
breaks fairly often.  

Once you have all of the cross sections cut out then start glueing them to the
panels. Line up the foam sections such that one face is over the marks locating
the cross section and the rest of the thickness is overhanging the panel. Since
the edge of the panel is all curves there's always going to be some overhang.
When all of the cross sections are glued onto the back panels you can clamp them
together for a rough look at the helicopter.

Hopefully you made sure that all of the foam sections were parallel when you 
glued them on the board. If you didn't, (like I didn't) it makes life a little
more difficult for the next step. What you have at this point are two back
panels with the foam sections sticking up from their surface looking a lot
like formers in traditional balsa construction. Between the foam sections will
be spaces anywhere from an inch and a quarter to two inches in width. I filled 
these gaps up by using the foam cutter like a table saw. I took the fence from 
my table saw and adjusted it for the size of each gap. Then I'd run a foam sheet
thru it untill I had enough layers to fill up the gap.

That pretty much does it for step one. We're ready to begin shaping the thing 
now but I'll save that for the next update. A couple of notes on things I
might mention. I used white glue on the foam. I found after a while that I
was getting carried away on how much glue I was using. Try to avoid getting
the glue near whats going to be the surface. White glue on white foam doesn't
doesn't sand/shape, it tears.

Dan Eaton

Step two in making the plug is as I said before;
2. Carve away everything that doesn't look like a helicopter.

Before doing anything else take a marker and outline the edges of the foam
cross sections that are lined up with the marks on the back board. Those edges 
are the true outline at that point. Now take the whole thing back over to the 
hot wire jig saw and run the wire completely around the edge of each half. The
outline was probably pretty broken up by the fill pieces and this step will
restore it. 

Now comes the part I hated. Take something like a Stanley Sur-form rasp and 
round the fill strips down untill they're about level with their adjacent
cross sections. Now go back and finish smoothing things out between the foam 
cross sections. Remember not to sand the edges you marked. When you're done 
you should be looking at a Hughs 500 C. It doesn't have a smooth surface but
it is recogniseable. The only exeception to this will be the very front. The
sides need to be brought in and it has to be done free hand. Just work slowly
and take a little bit off eash side at a time.

You can further smooth the surface by going back over it with a sanding block.
I found that 80 grit paper seemed to work well for me. The part I hate about
the procedure is that in the process of shapeing it you make about a zillion
little bits of styrofoam that stick to everything. I'd sit outside in the grass 
with a hose from my air compressor to blow things off when I'd need to clear the
work surface to see what was done.  Something else I didn't care for was the 
texture of working with foam. This may sound funny but I really enjoyed working
with balsa when I put my Jet Ranger together. Kay Fisher's "Stop and smell the
Balsa" quote really hit home when I started working on the foam. It may be quick
but it's not as satisfing to work with.

The good thing about this process is that you don't have to have any talent at 
sculpting to be able to produce something recogniseable. Before I built the 
Jet Ranger, I had a go at making a plug for a AH-1G from scratch. What I ended 
up with was asymmetrical and couldn't even be finished because I didn't have 
enough talent to shape one tricky section. With this method I know that unless 
I really screw up, both sides are symmetrical and the shapes are all built in. 
Another good thing about foam in general is that if you screw up you can cut 
the bad section out, glue on a foam block, and then and it down to the proper
shape.

Dan Eaton

    I thought I'd better put a little note in for the people who were
    interested in this topic. I haven't forgotten the Hughs 500. It's
    stalled for right now while I correct some problems I found after
    flying my Jet Ranger.
    
    The Jet Ranger weighed in at 11 1/2 pounds when I took it to the
    field. Although I was able to hover my poor little OS50 couldn't
    keep the rotor rpms up and it would eventually settle back in.
    After giving it a lot of though, I decided to strip the Ranger back
    down to the balsa, take some weight out of the tail, correct a couple
    of things that bug me, and then recover with glass cloth as per
    Al Casey's advise. 
    
    I've got at least three more weeks of work to do on the Jet Ranger
    before I can get back to the Hugh's 500. Sorry for the delay.
    
    Dan Eaton

    re .-1:
    Just a little clarification: Hughes is spelled "H U G H E S".
    There's an E in there. And no apostrophes. The plural is Hugheses.
    The possessive is Hughes'. The plural possessive is Hugheses'
    (We're going to the Hugheses' house today). The marvels of the
    English language!

    (no, I'm not mad, just want to set the record straight. And as long
    as I'm setting the record straight, I unfortunately have no ties
    to the aircraft company bearing my name. I think my father sold
    the rights for $1 to some imposter named Howard who claimed to be
    a relative.)

    Dave Hughes

    re:-.1
    Thanks Dave. I get cornfused sometimes. Especially since now days
    its spelled "M C D O N N E L L   D O U G L A S".   ;^)
    
    Dan Eaton