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



Item Description
Latest Instructions The latest set of 2.6m Instructions can be downloaded here (they are in .pdf format):


2.6m Yak-55SP Manual

2.6m Yak-55SP PhotoSheet


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?!
Ply tailplane anti-rotation pin supports are missing


Some of the earlier 2.6m Yak kits were shipped without the anti rotation pin's ply support ring on the inside of the fuselage. Whilst 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


Whilst 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 visit

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



Radio Installation


I have 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


A common 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


Due to 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


Below is 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 !


Right mouse click on the template, Save Target As and save to your hard drive. Then open the picture up in your image viewing software (I use Paint Shop Pro) and print it. As a size reference check, the former should be 270mm wide. The pictures below show the cannisters installed in my Yak. NB Cut outs have been tidied up since the pictures were taken!!



Engine Stand-offs


I've had 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...



Canopy Tinting


Rather 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


If you 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


I have 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 your engine...


Alternative aileron servo mounts


If you'd 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....



Tailwheel mounting


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!
U/C Heat protection


You need 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 the legs....


Thanks Joe, very neat!


ZDZ-100 Installation


Several 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 acceptable) route!

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!

As it works well as an impact adhesive, just run a bead round the vent hole on the fuselage, a bead round the vent itself, leave for 10mins and then press in place - you're done!


If you're struggling to find this glue it looks like this..



CofG Position


A good 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.


Control Throws/Setup