Setting Up a Radian for ALES Competition and Sport Flying
Here are some articles, from our newsletters, about setting up a Radian for ALES competition. They are
written for folks with lots of experience building, setting up and flying RC sailplanes, not beginners. That's
why you'll find them to be anecdotal rather than how-to. Furthermore, these articles were published in a
February newsletter, hence the weather references.
It's Time to Spruce Up That Radian
With the upcoming club and ESL ALES contests it's time to start getting our Radians ready. If parts
aren't immediately available you could, as I have, end up waiting for a few months, so now is the time
to figure out what you'll need and place an order. I've had good results using a local hobby shop,
Willis Hobbies in Mineola, to order Radian parts. That's also where I bought my Radian. Willis did
better than Horizon Hobbies with a replacement Radian fuselage. I didn't have to pay shipping costs
and I didn't get a warped rudder from the fuselage being jammed into a box that was too small for it,
which is what Horizon did to me. Willis also has the servos, wiring and hardware needed to modify a
Radian.
A Radian has two outstanding design characteristics: it is built of foam and built light. That means
compromises all around, that, from a pilot’s perspective, can best be summed up as being in need of
constant inspection. Even between one flight and another, parts start moving around. If you’ve flown a
Radian through a whole flying season you’ve seen this. The battery slides forward on landings more
and more easily, thus changing the CG for the next flight. And the wings slide out of the fuselage from
flexing. Inspect!
If you are thinking of pumping your Radian up for better climbing performance, possibly with a different
propeller and battery, you should perform any required maintenance first and then go on with your
modifications.
Here’s what I do with a new Radian before that first flight:
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Replace those thumbscrews on the pushrods if the Radian came with them. The thumbscrews
break for me, even when I’m careful tightening them. They break for new pilots leaving them
stranded on the field with an un-flyable plane.
Relieve stress from the pushrods being bent to connect to the flight controls. That means putting in
new bends positioned where they won’t run into the pushrod tube. The same could also be done
inside the fuselage, at the servos, but it is much more difficult. Why bother? Less bending of the
pushrods results in less work for the servos and the battery to actuate the flight surfaces. In
general, they'll both last longer.
Install a nylon hinge at the bottom of the rudder. It seems to be a weak area. In my first Radian
fuselage it didn’t last long before cracking and in my second one it was cracked to start with.
Nail that ESC down so it stays in one location. A piece of Velcro glued to the ESC’s covering will do
the job. Gluing with silicone rubber or some glue that stays soft will help prevent putting undue
pressure on any single component.
Tape around the fuselage, just in front of the rudder, to help stop the pushrod tubes from pulling
away from the fuselage. Landing a little sideways is all it takes to pop them loose.
Tape around the fuselage, behind the wings where the back and front of the right side of the
fuselage come together. You should get some glue in there if possible before taping it. After a years
worth of flying mine came apart there and then that led to the fuselage splitting right up the center.
Tape around the thin section of the fuselage, just over the wing. This is another weak area. Less
tape is better, so the wing continues to be held in by friction.
Paint or tape the wings to make yours unique and so it shows up at a distance. Consider flying in
an ALES contest with ten other Radians. How do you tell one from the other.
Here’s what I do with a used Radian for repairs and preventative maintenance:
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Clean out the nosecone. It’s part of the motor and battery’s cooling system. If you land in mud, dirt
or grass or simply fly though a cloud of bugs or dust, it’s all the same: the cooling holes are being
clogged up; sometimes faster, sometimes slower. It’s cumulative.
Check the wiring. Wires fray. Connectors pull loose. Antenna wires migrate from one position to
another.
Check the motor's fuselage mounts. Take out the three screws at the rear of the nose, slide the
nose slightly forward and check that the plastic pieces the screws are screwed into in the fuselage
are secure. I’ve found as many as two broken loose at a time. When re-attaching the nose, make
sure the motor’s wires or any other wires do not rub against the outside of the motor. The reason is
the case of the motor turns and will rapidly wear down the wire’s insulation creating electrical
problems.
Horizon Hobby has a toolkit for the Radian, but I found the only new tool I needed was a 1.5mm
hex driver for the aluminum adapter attaching to the motor shaft. I got that from our local hobby
shop. By the way, if you replace the propeller blades, don’t remove the pins that hold them in. Just
slide them both to one side: the side that is easier to slide them towards, remove and replace the
prop blades and then slide the pins back in.
Check the leading edges of the horizontal stabilizer. The construction is a thin layer of plastic
covering over the horizontal stabilizer. Over time the covering splits right on the leading edge of the
horizontal stabilizer. It may look fine, but when flying it opens up to form a drag chute. I used to
place a thin strip of packing tape over the leading edge, but then I found the elevator starts getting
floppy at this point in its life. Now I replace the whole elevator assembly and save myself a lot of
fiddling around.
Check everything after flying and before putting it away: You don't want to start packing your
Radian up to go flying and find out it can't fly or worse: find out when you get to the field. Go over
the whole plane in detail. Make sure everything is where it belongs and secure. Are the servos
glued in securely? How about the receiver? Cracks or breaks in the foam; especially around the
nose? Cracks or breaks in the wings? Bent fuselage? Melted or overheated wires? Puffy
battery? Binding controls? Motor turns easily (taking the prop brake into consideration)?
Appropriate information affixed to the plane to identify yourself and that will satisfy the AMA?
Here’s what I do when repairs and maintenance go beyond tape and glue:
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Get replacement parts for the Radian at your local hobby shop or direct from Horizon Hobby. If you
use this link to Horizon, click on, Parts & Accessories, when you get there. As a matter of fact, now
is a good time to order spare parts.
Don’t forget to check and re-balance the sailplane after making changes. The center of gravity of a
stock Radian should be 2.5 inches (63mm) behind the leading edge of the wing, when measured
against the fuselage.
How to store your Radian's lithium polymer battery:
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Battery University
Visible in the picture, the thumbscrews are replaced with screw type connectors, pushrods are bent to
reduce friction and thus loads on the servos, a new lower rudder hinge is installed and the pushrod tubes
are taped over.
The fuselage is taped around a weak area: right where it goes over the wing.
A blob of silicone glue on the back of a piece of Velcro is used to hold the ESC in place (away from the
motor). A little is good. A lot inhibits cooling of the ESC.
The Velcro and ESC are positioned. After the glue cures the ESC can be repositioned and it will stay put.
Check out the LISF ALES Builds thread for more details.
References
• February 2012 newsletter
• LISF ALES Builds Thread
Pumping Up That Radian's Rate of Climb
Are you thinking of modifying your Radian for better climbing performance? How about
changing the CG to get it to indicate lift better? Well, it's good news, bad news. The good
news is you'll find some of our club members are ahead of you, so you'll be able to check out
the changes to their Radians and the improvements their changes made or, in some cases,
didn't make. The bad news is, with the weather going the way it is, you'll be lucky to see them
flying by March or April.
The most common change is using a different propeller and battery to be able to climb faster
and range out farther. Notice that key underlined word, “and”. A different prop is chosen to
increase the amount of bite the propeller has of the air as it turns. More bite means more
current draw and if the battery can't supply it, besides not getting the performance the
propeller is capable of, bad things start to happen to the battery. You need both.
One of the first things an engineer does, besides finding someone else to do the work, is
establish a baseline to compare changes against. This quick test gave me a feeling for what I
needed to accomplish by modifying my Radian so it could climb at a higher rate. When I say
Radian I mean the original RE Radian, not a full house Radian Pro. By the way, the Radian
Pro, being a little heavier than a standard Radian, and powered the same, can't climb as well.
I launched my basically stock year old Radian with a CAM altitude limiting device, the repairs
and modifications shown in the previous article, a fully charged year old battery and tried to
get to 200 meters in 30 seconds by flying at an optimal forty-five degree angle. As you might
expect, the motor cut off at thirty seconds, well before getting to 200 meters. I restarted the
motor and climbed again until the motor shutoff after about five seconds.
Since it took a total of about 30 + 5 = 35 seconds to get to 200 meters, the climb rate is 200
meters / 35 seconds = 5.71 meters/second. And the altitude climbed to when the CAM
altitude limiting device first shut off the motor was 30 * 5.71 = 171 meters. By the way, if I
were to repeat this test a second time without charging this battery, the launch altitude would
be lower.
Optimally, 171 meters or 562 feet is about what I can expect my stock Radian to climb to in 30
seconds for a ALES contest. Your altitude may vary. If I want to get to 200 meters or 656 feet
in 30 seconds something is going to have to be changed. Since this is a contest plane I don't
want to merely climb to 200 meters in 30 seconds, I want to get there in far less than 30
seconds, so I can use that extra performance to range out as well.
Here is a link to help justify the use of the word "optimal", above: Vertical Climb Rate Versus
Launch Angle.
You read the article, didn't you? You should, but here's the pertinent data in a nutshell:
To read the graph, follow the blue line (climb rate). It peaks at about 45 degrees.
45 degrees is calculated as the optimal climb rate for the Radian.
So how do you modify a Radian to get a better climb rate for a club or an ESL ALES contest
or plain old sport flying? I'll get around to that, but before I lose you, the bottom line is after
prop and battery modifications we measured 22.16 seconds to reach 200 meters. That's a
climb rate of 9 meters/second for the modified Radian versus 5.71 for the stock version.
For my climb rate modifications I removed the stock parts and used the following in their
place:
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Thunder Power 850mAh Pro Power G6 65C Li-Poly Battery Packs
Type: Pro Power TP850 3S (Light, but good for only two ALES launches.)
PPTP-850-3S65 $32.00
Aeronaut CAM Folding Propellers (Rudi Freudenthaler)
Size: Aeronaut CAM 11 x 6
AER7234/39 $13.00
BB Aluminum Spinner for Folding Propellers
Size: BB Folding Alum 50/4/8mm
BBMDK50403 $28.00
Ron Macklin used a Graupner CAM Folding Prop size 10 x 8 (6mm shoulders) costing $11
plus shipping. He said that, they installed fairly easy but required that you drill out the plastic
holes on each new prop blade so that they are larger to be able to fit the stock metal shaft.
So Ron used a less expensive propeller and didn't even need to replace the prop's spinner.
Smart!
Ron's cost conscious propeller modification. It even retains the stock spinner cooling hole. You can read
more about Ron's propeller modification online.
My overpriced propeller modification. Where's the prop spinner's cooling hole? Oops. They do sell a
version of this prop spinner with cooling holes.
Now that you have a Radian that climbs better, what is your strategy for using that capability?
I see pilots simply climb for the moon: going up as steeply as possible. Their motor turns off
before anyone else's and then they give up that altitude cruising towards where someone else
found a thermal only to get there and find they're too low to use it. Here's my strategy. It just
maximize my usage of the modified Radian's improved climb rate. I head out close to where I
want to be and then climb to 200 meters just before the 30 second motor on timer runs out.
It's a simple strategy to be sure, but if I know where a thermal is I can get to it and be higher
than if I went up to 200 meters first and then cruised over to it without power. Alternatively,
when I have absolutely no idea where a thermal is, I fly upwind as far as I can, about 45
degrees to one side or the other of the wind direction, climb to 200 meters just before the 30
second timer runs out and head crosswind while letting the wind blow the sailplane back. The
sailplane isn't fighting the wind after being powered off and it's seeing new air all the time
while looking for a thermal. Well that's my strategy. You can probably do better. Create your
own strategy or copy someone else's, but have a strategy before you go into a contest.
What else can you do to increase the performance of your Radian? My best suggestion is
practice flying your modified Radian on the field. Second best is practice flying with a
simulator. Third best is adding flaperons. However, adding flaperons to a Radian has the
drawback of adding weight and drag which can be a real handicap in light lift conditions.
What flaperons give you is the ability to regularly get landing points. You might want to
experiment further with them. I've tried, but haven't been able to see any consistent
changes/improvements to thermal turns that I can't credit to my imagination. The same goes
for using flaperons to change camber, except to say that at the very least they add drag.
Check out the LISF ALES Builds thread on RCGroups for more details. If you update the
thread with new information and pictures that would be a great help.
Reference
• Vertical Climb Rate Versus Launch Angle
• LISF ALES Builds Thread
Adding Flaperons to a Radian
Note: Since the original of this article was published, in October of 2012, Parkzone may have
stopped making and shipping new Radians with decalage problems.
Paul Naton put a free video on YouTube outlining
the modifications he did to a standard R/E
Radian to be more competitive in ALES contests.
Two of the modifications are corrections for the
Radian’s overly conservative design: removing up
decalage and moving the CG back. These two
modifications go together hand in hand. A more
neutral pitch control makes for more precise
flying and lift indication. Another modification is
adding flaperons. When the flaperons are used
as flaps the Radian is better able to capture
landing points in an ALES contest.
To perform these modifications on my Radian I
put everything together with parts and servos out
of my junk box, so it didn’t cost me anything
except time. The primary tools I used were a
screwdriver, razor blade, an exacto knife, a
soldering iron and a sharpened 1/4 inch brass
tube for drilling a servo wire hole in each wing.
The soldering iron was for extending my servo
wires. The electronic parts that were added were
just some used HS-82MG servos.
I decided to go with heavier servos that could
take some abuse: like forgetting to raise the flaps
just before landing or climbing with the flaps fully
extended. By the way they held up to both these
forms of abuse. To connect everything together I
used the control horns that normally go on a
Radian’s rudder, wire pushrods, some longer
screws for the control horns and lots of packing
tape. Since this is a foamy, I was able to get
away with using very little spit and hardly any
glue compared to doing the same things on a
woodie ship.
The Radian's AR500 receiver with its limited
number and placement of channels forced the
flaperons to be plugged into the aileron and gear
channels. In order to get flaperons to work with
this receiver I needed to dial in mixes in my
Spektrum DX-7 radio. The mixes were found on
the Internet (and are provided below). I ended
with two switch-selectable positions for flaps and,
as a bonus, the capability for snap-flaps when in
the normal flap position.
When acting as ailerons there is more down
movement than up, theoretically inducing yaw
during turns. The amount of rudder I have mixed
in and the polyhedral wing is probably masking
the yaw in turns or I’m incapable of recognizing it.
My intention is to avoid the problem altogether by
making thermal turns using the rudder only.
Alternatively, if the stock receiver were to be
replaced with a seven channel receiver, say a
Spektrum AR-7000 or AR-7010, the goofy mix to
get flaperons working would be replaced by
flaperons the way Spektrum intended them to
work with proper differential to eliminate the yaw
issue.
attempt to stop in time.
Obviously, if you want to continue using the DX-5
transmitter the Radian comes with, you could run
the flaperons off the gear switch and a y-cable.
But then they’d be flaps, not flaperons, and you’d
only have two positions: full on and full off. Still, it
might be all you need for landing control. You’d
also have to be on top of the elevator control to
prevent nosing up, which could be taken care of
automatically by the flap mixes in more complex
radios.
As far as test flying the modifications, I have to
say I’m happy with them. I tried the decalage
and CG modification first. Wow! Even on the
first hand throw I could see a big difference. The
sailplane flies very pitch neutral: it went where I
directed it using the elevator. Launching it for the
first time, I was impressed. It flew straight out in
a steep climb needing far fewer pitch corrections
than before.
I did the decalage and CG
modifications together and not one at a time. It
makes sense. The stock decalage is like having
up elevator compensating for a nose heavy
sailplane. Paul Naton tells us to reduce elevator
travel because the decalage modifications make
it more sensitive. I didn’t do this and had to use
small control movements during testing. You
may be sure I’m going to reduce it before I take
the Radians out again. Yes, “Radians”. I also did
the decalage modification on a motor-less Radian
with a hook in it for practice launching off the
winch. Both Radians, as expected, indicate lift
well. The flaps, even with only three positions,
work well enough to control landing angle and
speed. Maybe I’ll be able to learn to use them to
consistently hit the tape instead of landing short
when a little puff of wind comes along or
smashing my Radian into the ground in an
Reference
• November 2012 newsletter
• Paul Naton’s modification video
• Flaperon mix setup
Using the flaperons to give aileron functionality
adds some fun to sport flying the Radian. I use it
automatically, because the ailerons (mixed with
rudder ) are on the right stick in place of rudder
only. Rudder-only has moved to the left stick, like
a full house sailplane.
Hey, with these
modifications a Radian could be used as a
stepping stone for going to a full-house sailplane.
On the negative side the flaperons are moved as
flaps via a three position switch. This isn’t bad by
itself, but if you’re accustomed to using the
throttle to change the flap position you could end
up mistakenly grabbing the throttle out of habit
when landing. It might be better if the throttle
operates the flaps as we are accustomed to and
the motor be turned on by a switch that
automatically goes to off when you let go of it.
Bob Anderson’s Agima is set up like this. After
all, you only need the motor for thirty seconds of
full power in an ALES contest.
Some construction notes: 1). I didn’t need a
orbital sander, as Paul Naton recommends. I
used a new razor-blade to cut off a strip of foam
and create a bevel in the top of the flaperons for
the hinges. The hard part was accurately drawing
some straight lines to follow when cutting out the
flaperons. 2). I folded packing tape over itself,
leaving about one-third of the glue side exposed,
to be used as gap seals over the flaperons. 3).
After I cut out the wedge of foam for the decalage
modification, as Paul Naton shows in his video, I
moved it to the opposite side of the widened
horizontal stabilizer slot, to give the horizontal
stabilizer more support.
Two ways of looking at the same thing: setting up mixes for flaperons. The first has more
detail: snap flaps and the flap system has three positions. The second has better descriptions
of what each mix is intended to do.
Aileron on the receiver is connected to the right flaperon.
Gear on receiver is connected to the left flaperon.
Both flaperon servos point in the same direction as one is shown in the following pictures.
DX-7, AR500 & Dual Flaperons
Go to Mix#5 (Allows use of trim)
Setup: Master > Aileron
Slave > Gear
Rate +100%---+100% (May have to flick Gear SW)
Go to Mix#1
Setup: Master > Gear
Slave > Gear
Rate –100% -100% (May have to flick Gear SW)
This inhibits the Gear Switch
Go to Mix#2
Setup: Master > Flap (Aux#1)
Slave > Gear
Rate +100% +100%
This will allow use of Flap Switch (Flaperons)
Connect the 2nd aileron servo to the gear output on the RX.
Both flaperon servos point in the same direction.
Flaperon servo placement.
Flaperon top gap overlapped with packing tape to reduce drag.