AT THE HEART In many circles of modeling, there is a shortage of good compression motors a working volume of 2.5 cm3. The only satisfactory engine KMD-2,5 for the last time so decreased that the head is forced to look for ways of providing the club good motors.
Alteration of good glow engines compression is associated not only with unjustified costs. This work is laborious and requires special skills. And if it fails, fails so hard produced, scarce and costly “Kalinka”. Therefore, we propose to go the way of alteration of the well-known “Rhythm”, a massive and cheap, using parts of the province. The result is a Microdrive, a displacement of slightly more than 3 cm3, which can be used in training and in competition models of aircraft, ships and vehicles of those classes, where the limitation of the cubic capacity exceed 2.5 cm3. In addition, this alteration is also interesting because it allows you to use a separate qualitative parts and units of engines, the use of which the production version is impossible or difficult. So, motors that “Rhythm” in most circles are not in working condition due to wear and pairs, and the quality of carters, and especially landing them the shaft on engines MARZ is not possible to operate these motors on purpose, but only in the form of blanks for rework.
For modifying to fit the “Rhythms” of any releases. The most important operation is the boring of the crankcase under the cylinder liner from the Regions. If you do not possess a boring machine, we recommend you to make a device that is described in the book by E. Gusev and M. Osipov, “a Manual for avtomodelistov”. At the same time with the boring butt seat for the flange of the sleeve. The rest of the Carter “Rhythm” without any changes, as all the details of the crankshaft and Zolotnik wall. Still need only counterbore the cooling jacket to the dimension of the sleeve from Marz. Here you can do the usual lathe. However, the operation must be performed very accurately — completely bored shirt sleeve needs to be pressed into or under heating the jacket to 90-100°.
Alteration of the Microdrive:
1 — regular jacket “Rhythm” (the bore size “a” to determine the shell casing Marz), 2 — sleeve Marz, 3 — piston group of the District with a new rod, 4 — Carter “Rhythm” Assembly with the shaft (the bore size “b” to determine on the skirt of the sleeve), 5 — tin solder muffler, 6 — rod. The left shows the installation of the Carter angled the fixture in the Chuck of a lathe for boring and surfacing.
As already mentioned, from the Region used cylinder liner, and with it the piston controlsan. These items better to take from the broken engine, as even after a short break-in at TDC formed a ledge from the development sleeve, which does not allow the piston to move higher with increased progress on the new redone “Rhythm”. May have a little podrastet the sleeve at the top, as the serial parts of the District have very pronounced “cone” and when run-in is not excluded tuff liners.
Piston pin you can use serial, but it is better to make a new, elongated, shank Ø 4.2 mm, whereby at the same time and will be able to get rid of excessive play in the coupling of the finger — piston (socket in the piston pre-reams the same drill). The rod in extreme cases can also are taken be serial, but more useful to make a new, out of the hardened duralumin, having center-to-center distance equal to 25.5 mm. the Final operation is a sample of four flats on the flange of the sleeve under the screws of the head.
After thoroughly rinsing all parts in gasoline, a new Microdrive is collected, making sure that the locking groove on the casing located in front or in back of the crankcase to prevent the ceasing of the piston pin in the purge channels of the sleeve.
Reworked the way “Rhythm” is a good start, stable performance and power close to the power of good documentation. However, this power to “the Rhythm” is realized at lower RPMs — due to the increased torque that allows the use of propellers of larger diameter in the enlarged cord aerobatic model aircraft for flying in the cords with a length of about 18 m. In some cases it is useful to provide the motor with a silencer welded out of sheet metal. Its configuration may be different; with success tested on a converted “Rhythm” are shown in the figures.
In radiolarian engine, it is easy to equip and the managed carb if you use the rear wall from KMD with the spacer thickness of 5 mm and replacement futorki radiolaboratory.
A. ZAGORODNY, head of the society

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