Nyrod control eliminates having to bend Wire Pushrods
As one of the most outspoken modelers about the lack of quality mechanical retracts on the market today, I was excited when I was asked to review the newly released mechanical retracts from 3DX-treme Hobbies
The Retracts were originally designed, built and tested by RCU's Mike Buzzeo (MinnFlyer) when he was also dismayed by the lack of quality retracts that were available. Over the next few years Mike fine-tuned the design to the point where everyone who saw them asked where they could get a set of their own. So finally, he contacted 3DX-treme Hobbies who agreed to put them into production.
So let's take a closer look at what 3DX has to offer!
3DX-treme Hobbies 40-60 size Retracts
Length:1.75 in (44.5 mm)
Height: 1.0 in (25.4 mm)
Width (w/ Mounting Tabs): 1.7 in (43mm)
Width (w/o Mounting Tabs): .8 in (20.3 mm)
Weight: 3.7 oz (per pair less struts)
I received the Retracts in the mail and upon unpacking, I found 2 bags with each bag having a Retract Unit and the Actuator Pin. Also included were two 3/16 inch struts, as well as the Instruction Manual.
The units themselves are CNC Machined from solid T6011 Aluminum stock, and the Actuator Pin is made of brass. Each unit is 1.7 inches wide, 1.75 inches long and 1.00 inches high and they have 4 holes drilled into the mounting plates. The included struts are 3/16 inch piano wire and are 9 inches long. The struts that I received did not have coils, but later shipments are being sent out with one coil in them.
I reviewed the instructions and found something that makes these retracts a step above the others. One of the hardest things to do with mechanical retracts is bending the wire pushrods between the retracts and the servo and 3DX-treme has fixed that problem. The Retracts are designed to use Nyrod and the units are drilled for Nyrod to fit into them perfectly. A really nice touch!
I selected the Great Planes Mustang for the test model. I followed the kits instructions for construction, although I did add some triangle stock to the retract mounting plates for added strength.
The retract units were mounted using 4 wood screws. I then routed the Nyrod's from the retract units to the servo area. On the retract end a short piece of 2/56 threaded rod is inserted into the Nyrod and the brass Actuator Pin. On the servo end I used a 2/56 inch push rod to connect to the servo using Great Planes quick connects. The use of Nyrod's saved a lot of time on the installation!
I then built the wheel wells, which are on top of the Nyrod and completed the construction of the wing. After the construction was finished, it was time to set the Struts to the right length. They attach to the retract unit using a set-screw. You must file a flat spot on the music wire prior to installing them in the retract unit to keep the struts from rotating. Wheel axels are not supplied so I used a set of 3/16-inch Great Planes wheel axels. These are also set-screw mounted, so filing a flat spot on the strut is again required.
Once the wing was complete and covered, I discovered the one problem that I had not thought about. Sliding the inner Nyrod into the outer Nyrod in the tight quarters of the mounting rails was a bit of a challenge. By following the kit instructions, you are told to sheet what is the top of the wing. It is at that point in time the Nyrod and 2/56 threaded rod needs to be installed into the brass slide rod. Had I planned a bit more, this would not have been a problem. I had to slide the outer Nyrod back into the wing a bit and then slide the inner Nyrod back into the outer piece and then slide to outer piece back into the retract.
Note from MinnFlyer: This problem can be avoided by not anchoring the Nyrod at the Retract end (The retract unit itself will serve as the anchor) allowing the outer nyrod tubing to move a little more freely.
Once I got both sides done and hooked up to the servo the first tests took place. The Retracts are smooth in their movement and lock both up and down. They have an adjustable over-center spring to help compensate with any wheel weight issues. I used scale wheels from Robart and I did not have to touch the spring adjustment. The plane was ready for flight tests. To bad the weather was not.
The flight tests were conducted with the weather being less than ideal. Under the threat of snow and rain, I gambled and got in some great test flights. The plane flew right off the runway with a touch of left aileron trim and after a few "Lets get familiar with the plane" laps around the field, it was time to bring up the gear.
I flew several laps around the field and cycled the gears many times. The moment of truth is always the landing and, as is just my luck, on the down wind leg of my approach the engine went dead stick. I was still really high and as I made the turn for approach I had to drop a lot of altitude to set it down on the runway.
When I touched down, the plane was really moving. It went the full length of the runway and off into the overrun which is grass and gravel. The right side wheel fell into a puddle, causing the plane to whip around and finally come to a stop after scraping its nose.
After cleaning up all the water and weeds from the plane, I conducted an inspection of the landing gear. There was no damage whatsoever. All I had to do was pull some weeds from in between the tires and the rims as the plane had slid sideways.
I am very impressed with the Retracts. They have just been put through the toughest landing that I can think of and are completely without damage or failure. There is no doubt in my mind that these units will handle a lot heavier and larger airplane and are designed with durability in mind.
The comments, observations and conclusions made in this review are solely with respect to the particular item the editor reviewed and may not apply generally to similar products by the manufacturer. We cannot be responsible for any manufacturer defects in workmanship or other deficiencies in products like the one featured in the review.