2.6m Yak-55SP Hints, Tips & Information
This page contains items that may help you whilst building and flying your Composite-ARF 2.6m Yak-55SP. The items are in no particular order.
It should be noted that you will still have a 100% capable model should you choose to build your Yak exactly as per the standard instructions.
Check the gallery here and equipment list here
latest set of 2.6m Instructions can be downloaded
here (they are in .pdf format):
Carbon U/C legs are a loose fit in the glassfibre U/C sleeves
|Some people have noted that the carbon u/c legs are a slightly loose fit in the glassfibre sleeves. The best solution so far to this is quite straightforward. Use some tape wrapped around the legs - as much as is needed to increase the diameter of the legs so that they are a snug fit in the sleeves. Simple eh?!|
tailplane anti-rotation pin supports are missing
the earlier 2.6m Yak kits were shipped without the anti rotation
pin's ply support ring on the inside of the fuselage.
you can fly the model without this ring (you would need to keep an
eye on the area to make sure it didn't open up and loosen over time)
it is worth fitting a plywood 'ring' on the outside of the fuselage.
It needs to go on the outside of the fuselage due to the lack of
access from the inside. The following shots show a good way of
carrying out the fix....
Thanks to Vicster for these shots.
Metal Arms for
Aileron & Elevator Control Linkages
the standard phenolic servo arms supplied with the kit are more than
adequate (ensure you take heed of the info here) several people
prefer to switch to metal arms. I have switched to metal arms to see
if I can find any advantages. I use the recommended JR8511 and have
use 1.5" SWB metal arms. I can thoroughly recommend these arms as
they often extra security from the 'Double-Loc' feature which means
that as well as the standard servo screw they are also clamped to
the output shaft via a second nut and bolt. For more details you can
These arms come with a 4-40 thread which is popular in the US but as I had a lot of 3mm bits and bobs floating around I simply tapped the holes to 3mm.
Fitting these arms will require you to widen the slot in the tailplane for the control arm by about 4mm as the arm sits a lot closer to the servo than when using the standard setup. This is dead easy to do with a sharp blade. The aileron horn slots won't need widening if you fit these arms whilst building the model and position the servo mount suitably to ensure the arm is central to the slot. If, however, you retro fit the arms, as I did, you will need to widen these slots too. I simply used a file to open them up about 3-4mm.
The best control linkage method with these arms is to use a ball link on the servo end. DO NOT USE A BALL LINK ON THE PHENOLIC CONTROL HORN END. The phenolic horn is more than strong enough in the direction of force it needs to be - years of use and abuse has proven this to be the case but using a ball link introduces a twisting force which will snap the horn. This has been proven so please take note!
A couple of shots of my linkages are shown below
had a few mails asking how I have installed the gear in my Yak. The
pictures below will show what is where. So far this has turned out
to be a reliable installation and resulted in the CofG being just
right. Bear in mind the position of the batteries is due to having
cannister mufflers installed.....
I have my aileron matchboxes installed at the wing roots and have one lead coming from the RX to the matchbox - keeps the rigging as simple as possible at the field. Also worth writing which servo is which on the root web to help with setup etc. See the pics below...
Positions for the closed loop cable exits
question is 'where do I make the exit holes for the closed loop
cables?'. Well, several builders have agreed that the following
dimensions should be followed as an answer to this question!! It is
important to note that this is based on a closed loop setup that
does NOT have crossed cables but has the cables running parallel to
one-another all the way to the rudder horn.
Making your fuel tank tray removable
the size of the tank tray and the fact that it covers most of the
radio compartment, it is a great idea to make the tray removable.
This way, maintenance is made a lot easier as when access it
required to your radio equipment. It is a very easy modification to
make and certainly worth doing. The pictures below give a good idea
of how such a set up can be easily achieved. Remember to use some
ply plates as shown so as to allow the tray to be tightly secured
without crushing the balsa.. The captive nut and bolt show in the
first and second photos is for illustrative purposes only and shows
the captive nut and bolt concept used to hold the tray in place.
Thanks to Joe Gredler for these great shots.
Template for cannister muffler installation
a template to help you if you plan to fit cannister mufflers in your
Yak. If made exactly as per the template, a pair of 60mm diameter
cannister mufflers will be a nice snug fit in the holes once they
have been lined with tygon tubing as shown in the photo. Obviously
you can make the holes to suit your whichever cans you have used !
a few e-mails asking what length engine stand-offs are required for
the DA100. The simple answer is that no engine stand-offs are
required. The engine needs to be about 6mm away from the bulkhead in
order for the prop to clear the cowl. I simply use a washer and a
wheel collet between the bulkhead and the engine backplate. The
photos below show the setup on my Yak and also the clearance the
setup gives me...
than messing about with large tanks of hot water and dyes, simply
use some 'tint' spray that all the R/C car boys use - anywhere that
sells model cars will probably sell the cans of tint. The darkness
of the tint can be built up until you are happy with the look. One
thing to ensure with this approach is that you thoroughly wash your
canopy in warm soapy water - take it in the bath with you!! If you
simply give it a dust beforehand then the tint will not adhere
equally as there is a releasing agent of some description on the
canopies which the tint won't stick to properly. Make sure,
obviously, that you thoroughly dry it too before spraying!
You can see the overall affect the tint achieves in the picture below.
Alternative 'bolted on' canopy method
hate gluing canopies then another option that I think looks quite
cool is the 'bolted on' canopy. I have used 3mm bolts and nyloc nuts
spaced every 2" although 2mm may look better due to the slightly
smaller size. Use masking tape all round to hold the canopy securely
in the correct position within the canopy frame. It is best to do
this with the frame on the fuselage so as to ensure you don't twist
the canopy frame or at least mount the frame on the fuselage
afterwards to ensure you haven't twisted it. Now drill through the
frame and canopy at the top rear centre and the front centre
approximately 1/2" from the edge of the frame and secure with a nut
and bolt. Mark the rest of the holes on the masking tape, drill the
hole and fix with the nuts and bolts as you go checking every now
and then that the frame is not twisting in any way. The photos below
help highlight the process..
and when you're done your canopy should look something like this.....
Throttle Servo Arm Slot Position
had a couple of e-mails asking where the slot should be cut for the
throttle servo arm as this is not in the instructions. The following
diagram shows where I have my slot cut. Bear in mind that these
dimensions are for a DA-100 installation. If you are using a
different engine then do not assume these dimensions will work for
Alternative aileron servo mounts
rather not use the plywood servo mounts supplied in the kits then
the JR servo side mount is as excellent alternative. Rather than
gluing the mounts to the servo bay covers I prefer to use 3mm bolts
and nyloc nuts. This results in a very strong setup. When
positioning the servo mount remember to take into account the
thickness of the servo arm you are using so that the arm is
positioned centrally to the slot in the servo bay cover plate. When
finished you'll end up with a servo setup like this....
Due to the curved nature of the Yak's fuselage, your money will be best spent on a tailwheel of the 'wire' design. These are available from Composite-ARF's website but when mounting the tailwheel you will need to bend the clamps to conform to the shape of the fuselage. This can easily be done with some pliers. Take note of where the plywood support is inside the fuselage before you start drilling! The following photo shows how the clamps have been bent to shape.
Yellow paint to colour code the cooling vents
|If you wish to colour code the two white cooling vents that cross the yellow stripe of the fuselage I have found that Humbrol Enamel number 69 Gloss Yellow is an almost perfect match.|
Header Pipe Couplings
|Ditch the spring clips that often get supplied with headers/cannister mufflers!! They are not tight enough to stop exhaust residue from seeping out and caking your model! Get hold of some suitably sized jubilee clips and tighten them right up. Leak free for ever!|
to ensure that the exhaust system you employ is kept a suitable
distance from the U/C leg sleeves so as to ensure the heat from the
exhaust does not soften and damage the resin. Joesef Gredler
produced these very neat items to help reflect the heat away from
Thanks Joe, very neat!
people have asked whether the ZDZ-100 will fit in the 2.6m Yak. The
obvious answer is 'Yes' but due to the model being designed around
the DA-100 there are a few 'changes' required. Josef Gredler
(again!) kindly sent some pictures of his ZDZ-100 installation that I
hope will help others who choose to go down this (more than
The first two pictures shows the choke linkage that is operated from the front through the cowl. The third shows the throttle linkage. The fourth shows the cut out required in the bulkhead for the rear mounted carb on the ZDZ. The final picture shows the required position of the throttle servo.
Cutting out the cooling vents
Video coming soon!!
Gluing the cooling vents
I have found that UHU
POR glue (the gluethat comes with the electric ShockFlyers) works
great as a glue for the vents. Stops the problems with cyano running
everywhere or epoxy getting places it shouldn't!
If you're struggling to find this glue it looks like this..
way to balance your Yak is to have it ready to fly but without the
wings on. Next use a finger in the wing tube sleeve each side to
life the model up. The suggestion is to have the model balance level
but I have found that it is better if the model slowly drops its
tail indicating a CofG that is slightly further back than originally
suggested in the manual.