Flying Information
In Depth...
Hirobo Freya Evo 90
By MHtjef
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Inverted Baby!!! |
The Freya line of helicopters have been
around since 2000 when it was first shown
and flown at the IRCHA Jamboree, when
the Jam was at the Hebron site ... and with
Bennett at the controls no less! Jeff Green
told me that even Hashimoto was there to
show it off. Remember that old spindly
landing gear? This latest version is the
result of MRC’s heli guru and all-aroundgood-
guy Jeff Green plus Hirobo putting
their collective brilliance together to make
a five year old design even better. That
whole refinement process is what has kept
many in the machine making businesses,
like Porsche or Acura, at the top of their
game and provides us machine lovers with
continually improved products. The fact
that the basic Freya has only needed a new
rotor head and a few frame tweaks to
become this latest version is a tribute to the
knowledge of the engineers, the R&D
pilots, and the Freya’s basic good design.
The original Freya has become sedate by
2006 standards and was in need of some
upgrading to suit the furious 3D that goes
on here in the USA. Old Freyas are still a
good bet for a beginner, but beginners here
in the USA don’t seem to stay beginners
very long lately. Having had success with
the Sceadu Evo50, the decision
was made to pursue shooting
steroids into the Freya. I heard,
from Mr Green, that Hirobo was as
serious as an IRS agent about
getting the right combination to
wow the USA 3D intermediate
market.
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There is no denying the fact that
I like the Hirobo lineup. The quality
of the parts, slick assembly of the
machines, and their knowledge of
how to build molds to make parts
and machine aluminum is very high.
I’ve designed many an injection
molded part in my career as an
industrial designer, and have been
involved in many complex machine type
projects so I respond well to a product
that clearly exhibits it’s commitment to
being above expectations. Because of
being complex by necessity, it’s not an
easy task to create a good RC helicopter
... or even a bad one. If it was easy, we’d
all be slapping them together like plank
pilots. Hirobo makes planks too, but have
a longer history of making good RC
helicopters, so they have gathered a large
base of knowledge of how to do it. Another
thing worth mentioning is that Hirobo
never seems to fall prey to the lure of
cheap, crappy molding resins or shoddy
manufacturing techniques. Does all this
love language leave me a hopelessly biased
reporter? Not at all! Not even when MRC
supplies us with a machine, gratis. I think
MHT readers realize this by now, but it’s
good for me to restate it in print, for my
own invitation of accountability from you.
Not being biased has caused us a few
problems along the way, but that goes
with the turf I guess.
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Putting bravado aside, I was thinking that
a word from the sponsor would be a great
addition to this review. I’m betting that you
might like to hear the inside skinny about how Mr. Green and Hirobo put this machine
together. I told Jeff he could have the space,
but that the caveat is that he needed to be
honest and authentic ... which I have come
to know is a big part of who he is ... which is
why I thought that offering him this
opportunity might be something good for
the readers and MRC/Hirobo, and Jeff Green.
Here is what Jeff had to say:
“MRC’s involvement in the Freya Evo project
began in the summer of 2004 with a market
report and a USA helicopter wish list requested
by Hirobo. There were many conversations
and trips prior to the report and wish list, but
the submission of the market report and wish
list was the real
beginning of the
MRC’s involvement
with the Freya Evo
project. The “wish list”
was comprised of
thoughts, ideas, and
suggestions from the
Team pilots and
consumers together.
Each idea was
considered and a
formal list was created.
In November 04, we met
with Hirobo’s R & D staff. At the meeting were
Mr. Uebori, Hirobo’s engineering manager, Mr.
Hashimoto, Hirobo’s multiple World Champion
pilot and his Mentor, Coach and Top Hirobo
adviser, Mr. Kurokawa, an experienced, very
knowledgeable heli “guru” to say the least.
From this list, Hirobo accepted and eagerly
incorporated the ideas we jointly created for a
basic model and added even more performance
enhancing features from the Eagle WC3 and
Freya Ex -II. During that visit, we also tested
an initial version of the new rotor head with
good results. The meeting was very productive
and Hirobo was finely focused on this updated
Freya.
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A year or so ago MHT showed you how to install
strain reliefs on the tank clunk line. Use the system
here and you will be rewarded with a bulletproof
tank. |
In March of 2005, the first Evo 90 core parts
were tested in Japan. This was a big honor for
me personally, as this was the first test of
many and I was asked to be part of the
Hirobo in house development team. Really
cool! The experience that week was a lot of
fun and a lot of wrenching. The end result
from that week was “thumbs up” and now
planning for release was started. At the
Toledo show in April of 2005, the very first
full Freya Evolution 90 was was first shown.
This particular model almost did not get
tested as the airline lost the model while
flying home from Toledo. Fortunately it
showed up about a week later. Testing of this
model went well with about a gallon of fuel
per day being run through it. From the
beginning, there was a noticeable difference
in this heli. It felt light, nimble and was very
comfortable to play with. In May, selected
team members received more test parts and
testing was at full speed. Three of these test
helis were used at the XFC 2005 amongst
much more costly models with good results.
The Freya Evo is continuing to impress and
delight its owners (be careful Jeff! - ED). Hirobo
is listening to the USA market intently and a
good sign of that attention is this USA only
version of the Freya Evo90. The USA kit is a
90 size engine ready kit that also includes the
metal radius block, a third main shaft bearing
block, 8.45 gear ratio, and Teflon rudder control
rod protection sleeves. The kit does not include
main blades. The price of the kit was also
heavily considered and hits the streets between
$600 and 650.”
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A word of Note before we start. Be sure
you read all the instructions INCLUDING
the separate Appendix sheets. I could have
avoided a problem, involving the above
mentioned teflon sleeve I might add, had
I been more fully conscious of those sheets
- more on that later. On to the review....
First off, there are a few steps in the
build process that need to be singled out
for clarity or improvement. Some of the
improvements are from the experience I
have had building and flying Freyas over
the past few years.
Step 1: Elevator assembly. Four of the
pivot screws that come in the kit are of the
sheet metal type (M2.6x8TS-2) and can be
hard to get through the pivot bushings
(Brg. 03x06X2.5FZZ). To solve that on the
three Freyas I have built, I substituted
four 2.6 Pan-Head Cap Screws, 8mm long.
These work very well, take up very little
space inside the frames, and have
presented no long term problems. Be sure
that the bearings go fully into the arm and
that the links up to the swashplate pivot
freely with no slop. Using the cap screws
allows you to easily tighten things up later,
if wear shows up, without having to work
a JIS screwdriver between the frames.
Step 3: You will need to be sure that you
attach the canopy standoffs before you
screw the frames together (duh-o). Another
trick here is that the central set of the
Freya’s stacked main frames came in the kit
loosely fastened together. I’ll bet this was
done to insure against warps after the
molding process.
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Shown is the Velcro strap around the frame to prevent
the pressurized tank from wearing againt the frame. |
Steps 5-6: The tank is located in six newly
designed rubber mount cushions and this is a
huge improvement over the original Freya and
the XSpec. You do not have to glue them in so
you’ll have them around for rebuilding. They
hold the tank very well. There are three
of them each side. I needed to add a
strap of Velcro around each rear frame
side to help keep the tank from abrading
against on the frames, due to the mighty
YS pressure system.
Step 9 is confusing. Step 9 appears
at the front of the instructions, before
Step 1 and reappears later in it’s
proper place in line. Ignore the first
one and build to the real Step 9.
Step 11: This is the most important
step in the Freya’s assembly. Follow the
instructions carefully, but heed the
following: There are two screws
M4x10CS and M4x12CS. These are
SUPER IMPORTANT as they keep
the head on and are known for
loosening up. Their security is noted
in the instructions by cartoon tubes of
“lock”. When these screws loosen,
you will note a change in tracking, or
lots of blade noise, or an irritating
vibration in the tail boom, or lack of
“crispness” in flight, or all of the above.
Red LockTite is what everybody uses
but I have found better results with
LockTite 601. It’s green but very thick (it
cannot be added to a finished assembly - it
has to be on the threads before assembling).
This stuff grips like an angry Pitbull, but is
less of a hassle to break free when you
have to repair things. Check the LockTite
site for more info on 601. LockTite is best
applied with a medical product turned heli
tool called Micro Brush. The best part of the
MB is that it can be cleaned and reused. I’ve
had these for years as well. A roll across a
paper towel will clean it fine.
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Step 14: There was a problem with early
versions of the metal cross member. The
part would break right beside the ball. I had
this happen on my machine and noted that
the only symptom of it’s failure was
vagueness in the cyclic controls. Only one
side suffered this malady. I figured out a fix
that was to be the subject of a future
HeliSmith, but J Green beat me to the punch
with a set of replacements. These are much
beefier around the ball feature, so that
shearing problem is no longer an issue.
These are included with current kits.
Step 15: Nothing to note here other than
the design of the flybar control system.
After you get this all assembled, you should
note that there is 170mm of flybar buried in
the control arm assembly within the head ...
so there is only 120 mm of exposed flybar
between the head and the paddles! There
will not be much flexing going on there and
that is evident the first time you fly: control
is crisp! Regular readers of MHT may want
to consult the Sceadu Evo review on how to
modify the flybar to make it easier to remove
and replace.
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Inverted Baby!!! |
A word about this new head design. It is
basically an enlarged Sceadu Evo head. Most
notable are the manner in which the mixer
arms are located and how
they act on the disk. This
head is called the FFZ III,
and is different from the
Sceadu head only in the
dampening method. Hirobo
is committed to the central
pivoting head feature on
their larger helicopters and
this head represents the
next step in that design. The
basic concept goes way back
to the early days of the RC
heli, and so it should be
considered to be proven.
How it differs from the
typical rigid configuration of
other helis is that the
spinning disk pivots at a
central point, just above the
disk, with the dampening in-line with the
feathering shaft, but just below the pivot. Time
for a proof of concept illustration. If you set the
center of a dinner plate, flat on
the tip of your finger and start
tilting the plate, you will get
a sense of how Hirobo rotor
disks function. It pivots
around your finger. Most
other helis use a feathering
shaft, supported by o-rings
either end. This system freefloats
with no central locked
pivot and is dependent on the
dampeners to carry a lot of
the load, both flight and gust.
The illustration here is putting
two fingers, closely spaced,
under the dinner plate and
tilting it. Now lest you think
that one is superior over the
other, you need to consider
that these systems affect what’s carried under
the disk rather than the spinning head itself.
Bottom line is that they fly a bit different but
do the same job. The big difference, from my
point of view, is like this: in Hirobo systems,
the disk as a whole “plate” moves to
change directions or compensate for gusts,
whereas the double supported system
uses half the disk to do the same. I
know I’m going to flamed on that one,
but think about that for a moment
before you send me the “you’re so
stupid” email. Grab a plate and try it
first. Hirobos have always been known
for smooth and predictable flight and
the above is a simple explanation of why.
The Freya system is more sensitive
to flybar paddle weight and design and
so tailoring this head design to your
flying style is simple. That is a reason
why you get the opportunity to play
around with with paddle weight
options.
Now to satisfy the USA market, the
Freya uses a new white dampener
rubber of harder durometer than the
older versions or the XSpec. These
dampeners generate just what I like:
crisp and predictable handling. I tried
a set of the Xtreme poly dampeners on
the older Freyas and did not like the
touchy feel they left me with: I do like
to hover some. These new white
dampeners are a way better compromise
than any other option.
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Inverted Baby!!! |
With the weights out of the paddles
the rotorhead is very agile. Flips and
direction changes happen right now! I
admit that I liked it best with the
weights in, however you could easily
experiment with different weight
combos by getting a few sets of weights
and cutting them to different lengths.
The FFZ III head also has a bunch of
optional ball-link locations for
Bell/Hiller mixing ratios to take you
from slow and steady to fast response.
Missing from the instructions is that
wonderfully simple High Mobility to High
Stability chart (XSpec) for clearing up
confusions over which holes to use in the
mixing system to hit your flying style. Too bad
too. Make your life simple: Setup your model
to the instructions and tailor the flight
characteristics with paddle weights. You will
be amazed how much an effect the paddle
weight has on this ship, no matter what blades
you fly.
Good news: this head accepts 690 to 710mm
blades. The bad news is that the grip opening
is huge, 17mm wide, and will require spacers
to accommodate your existing supply of blades
(although VBlades now has root thicknesses
to fit the Freya grips). I believe with the power
of the modern 90 2-stroke, this trend towards
the heavy duty stuff like larger roots and
bigger diameter blade bolts will become
standard practice. For example: The new
Synergy will be sporting a 5mm flybar!
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Inverted Baby!!! |
Step 18: SURPRISE! You get the top of the line,
blue anodized, aluminum EX Radius Block! Apart
from the motor mount, this is the only effective
bling you could add to make this ship better! Make
sure you set the swashplate phasing before you
fly. Otherwise your ship may do weird waltz moves
at the top of loops and such.
Step 17, 18, 19: Man it’s fun to spin these
bellcranks around and around. All controls are
closed loop.
Step 26: Boom supports. I didn’t glue the
ends on due to their mammoth construction
plus the use of a screw to hold everything tight.
This works well. How do I know? Because of not
reading the addendum sheet about adding the
plastic sleeve over the tail pushrod. Vibration
almost killed that rod but did not effect the boom
supports.
About that tail control rod: This is the only
place I can fault the Freya (see step 38 note). I
needed to refine that control run and we have a
how-to process with pics somewhere among
these pages.
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Inverted Baby!!! |
Step 27: I like the way that horizontal fin
looks but the sucker is too heavy!
Step 28: Worst part of the Freya build for us
lazy types is dial indicating the clutch shaft. I hate
doing this. Mike Fortune just did a great article
(#48) on this process and that can take some of
the pain away. If you do not get this right you will
be chasing the vibration virus all over your
machine and there is no antibiotic to cure it.
Luckily Hirobo get really close to 0 runout and
indicating doesn’t take long at all. Still, you have
to do it. My particular clutch was out .003. I
thought I could get that closer with the Foutune
Technique and I certainly did. Rotate the whole
clutch to get closer to zero and then dial indicate
the start shaft to get as close to .0000 as you can.
Step 29: You will have to either remove the
carb or the needle valve screws to get the
engine in to the frames. However, it is easier
to get the engine into the Evo than the XSpec,
due in major part to the molded-in cooling
ductwork in the Evo90’s frames. MHT has
an Avant here for review and because of that
fact I was able to steal the optional engine
mount off the XSpec for the Evo. I hear
that mount saves an ounce.
Step 30: I used JR 8311 servos for this
machine and am glad I did. The performance
that really good high end digital servos
provide will make any machine inspired. If
you have to spend money on blinging out
your heli, start with switching out the servos
to high end digitals. It’s money well spent.
The 8311s make the Freya Evo dream to fly.
Tic-tocs have sharp stops and starts.
Pumping moves are quick and positive. If
you like super snappy cyclic action, the
8311s combined with removing the weights
from the stock paddles makes that happen.
MHT’s Freya will flip in it’s own length
and pumping actions rival are no different
than the CCPM machines.
Step 34: Use the servo wheel
recommendations in the manual: you will
not be disappointed!
Step 38: Here is where my lack of following
directions caused me some grief, but also
led to the one area of the build that I think
is not up to Hirobo’s standards. The tail
control rod assembly is continued in the
#0414-927 Additional Instructions Sheet.
You need to read and follow the
instructions here carefully but you will also
need to follow the extra instructions on
page 36. I did not add the “fluoride” shrink
tube to the tail control rod initially. The
result was accelerated wear on the rod (see
pics), but adding the shrink closes the gap
in the guide-rings too much and that causes
the servo work too hard to move the
tailrotor. The fluoride (teflon) shrink also
cuts vibrations. Because I didn’t do the
shrinky thing, I wound up having to send my
faithful and hard working 601’s servo back
to Futaba service for fixing (and not total
replacement ... I hope!). So plan on at least
checking the assembly as you build step
38 ... take it and learn from the man who
made the mistake. By the way, the tail is belt
driven off the constant drive auto system.
Conclusions
All in all, this machine builds like all the
other Hirobo machines.The quality is
sublime and it’s hard to commit to getting
the machine all full of glow-slime.
And how does the Evo fly? Better than the
old version that’s for sure! If you want a
smooth FAI machine you can adjust it to do
just that. Want a hover only beginner
machine? It does that too. Yeah, but how
about pushing 3D? That too! Mr. Green has got a
good solid machine on his hands ... a much improved Freya.
I am very comfortable with way it flies and found that building
it exactly to the instructions was the best route to a happy
combination of 3D and smooth, fast, solid FAI-like performance.
It needs no bling. The negatives were the tail control rod
system needing some out of the ordinary attention and that
heavy tail fin. This heli will not fight you in long fast lines, and
more importantly remains predictable everywhere. Being
“predictable” is a wonderful benefit for advancing your skills.
“Predictable” provides a level of confidence that will inspire
you to advance. Well, that and cheap spares. The Freya Evo
90 is an inexpensive 90 powered machine that you need to
seriously consider for advancing your skills. You can try stuff
on this machine that you might not dare to with your Synergy,
and it will do things that a 50 can’t get to. A nice second level
feature of the Freya is the gobs of space under the canopy. It’s
gratifying to have options about where bulky avionics
equipment can get mounted. The finished ship weight in at
10lbs 13 oz. The Evo90 head handled 3D bursts very well. I
never feared that the blades and boom would meet, especially
during rapid pumps in any direction (8311s), or in outside
maneuvers. With the right blades on it, autorotations, even
with the drag of a belt tail, are excellent. In fact the VBlades
I was flying during the first gallon retained so much inertia
at the bottom I couldn’t botch one if I tried. This is the
machine to learn aerobatic autos on. I found that I could easily
move around to spot land, something new for me .... Look out
Lund! At around 625.00 a copy you’re not spending your
Starbuck’s money to have one plus a backup. It is a great
looking machine too. And it’s a 90! There is just no substitute
for cubic inches, eh!
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