Radiator - Oil Cooler Mount

This blog covers the manufacture and installation of the radiator mount

Overview
There are no details on mounting the radiator and after peering at it for a while a email was sent to the factory, a series of photos showing the factory mount were received but more importantly the mounting points on the engine shown - problem solved.

A 2D drawing for a Rotax 912 was located on the net and then a profile was developed and sent out for laser cutting in aluminium.

It was decided to mount the radiator in a flexible mount - to do this the four mounting bolts were secured through 6 mm OD grommets secured with flanged M6 bolts and large S/S washers. The grommets were mounted in seperate angle brackets with the top pair riveted and both lower brackets secured with M3 cap head screws fitted into rivet nuts - this allows easier installation.

The frame was assembled over the radiator, offered to the engine and secured using M10 Titanium bolts just to save a little more weight.

A good feature is that once the lower bolts are removed the assembly hinges forward on the upper bolts.

Oil Cooler
The installation of a Silent Hektik oil cooler removed the need to cut another opening into the cowl allowing better control the air flow in the long run.

Oil Cooler Schematic

Engine Cooling Schematic

The location for the oil cooler is behind the radiator mounted off the arm supporting the radiator. 

Radiator / Oil Cooler bracket hinged forward

The bracket was fabricated from aluminium sheet 0.030 and 0.020'' to provide the mounting points and stiffeners respectively. 

Construction was dictated by the folder but a satisfactory bracket was created within these limits and the cooler mounted using four [4] M6 x 20 screws through 10 mm spacers onto the base plate. 

All assembly was done using 3.2 pop rivets.

Oil Cooler Bracket

Radiator / Oil Cooler / Picture frame seal installed

Comment
The choice to install a duct from the inlet to the radiator precluded installation of a oil cooler under the nose and the water cooled option seemed to fill the need. The advent of the Vixen from Foxbat confirmed my decision has some solid ground, this aircraft is 20 knots faster than its predecessor the Foxbat on the same wing and motor. 

The air for the oil cooler is collected under the top lip of the inlet and ducted over the radiator to the oil cooler at 90 degrees to the radiator.

The primary difference apart from a different fuselage profile is a extreme upgrade of the air flow through the cowl including a radiator that is effectively ducted from the inlet. This is not the sum of the changes but may explain some of the speed boost.

The next task is the duct this will have a overall length of 175mm and will seal on the picture frame shown on the photo above with the biggest problem just plumbing all the hoses and this has thrown a few plans into a spin.

The good news the muffler, oil cooler and radiator fit into the area allocated, hoses are another issue as already stated.