Aeroovee to Rotax mount conversion???

[xeriotti]

I don't have any notes about the dimensions or weight of the ring mount. I can measure the diameter Monday if you still need it by then. I remember that it seemed heavy, but I couldn't make an accurate guess of the weight. The installation manual for the Rotax does have some useful dimensions for the attachment points.
Rusty

Knowing the weight would be important.... To make an estimation of the thickness...its obviously 4130 steel. So depending on the available materials to make my own mount...ill have to trade some weight to have correct safety margins.

Making my ringmount out of 2mm thick 304L stainless would result in a weight of 2.3kg (ring only without the tubes that go to the motor)

It seems light to me and making it out of 3mm thick wouldnt be soooo heavy... its would end up around 3.5kgs ring only. Then there are 8 sections of tube that go to the engines anchor bolts less than 20cms each...buts lets say they are 20cms each just for the calc... .... i have 1.8mm 4130 tube for that... it may weight around 1.45kg according to my calculation.

A total of 5kg for my homemade ring mount. beign really safe with 3mm 304L main tube and 1.8 thick 4130 legs.

[Kai]

Ive seen someone making an adapter from a solid piece os 12mm steel.... But i dont know...i calculated it to be around 3 kilograms for the plate only... Ill try to make something lighter without compromising strenght... (sounds easy XD)[/quote]

Yep- that was me!
Just to make it abundantly clear- the 12 mm thickness of the adapter plates was selected because of the aim to utilize (the already in stock) harder Sonex rubber isolators for the Jab33, as well as its mount. If someone could find 12mm Al 6061T6 or 7075T6, strength would not be compromised- at a lower weight. However, in this country, no such luck! The one big advantage of using the mount for the 33A, is that it pulls the Rotax as far back as possible (from heel to toe, with its standard ring mount, the 912 is even longer than the 33).

Everything said and done, the plane has been airborne for close to 50 hrs by now. So far, no nasty surprises- in fact no surprises at all. EW t/o mass with oil and coolant, but no fuel, came out at 309 kgs. The corresponding CG lies smack bang at 20% aerodynamic cord- the forward limit. The plane has been spun with 2 persons and half fuel: standard recovery works like a charm.

[xeriotti]

I
Yep- that was me!
Just to make it abundantly clear- the 12 mm thickness of the adapter plates was selected because of the aim to utilize (the already in stock) harder Sonex rubber isolators for the Jab33, as well as its mount. If someone could find 12mm Al 6061T6 or 7075T6, strength would not be compromised- at a lower weight. However, in this country, no such luck! The one big advantage of using the mount for the 33A, is that it pulls the Rotax as far back as possible (from heel to toe, with its standard ring mount, the 912 is even longer than the 33).

Everything said and done, the plane has been airborne for close to 50 hrs by now. So far, no nasty surprises- in fact no surprises at all. EW t/o mass with oil and coolant, but no fuel, came out at 309 kgs. The corresponding CG lies smack bang at 20% aerodynamic cord- the forward limit. The plane has been spun with 2 persons and half fuel: standard recovery works like a charm.

Kai! Ive seen your work! It would be my option to do it just like you, but my engine didnt come with any mount at all.... So...I have to couple the Aerovee mount to a plain Rotax.

What im trying to achieve is my own Ring Mount, with my own rubber damper sistem and Aerovee mount spacing. Im around 40mm forward of where the Aerovee prop hub would be...

[Kai]

There is always more way than one to skin a cat!
This one (Pay particular attention the the square tube stiffener bar between the two upper aluminium attachment angles in the airframe) is done by a guy in Sweden- scratch built from the ground up. The amount of work must have been overwhelming!

[xeriotti]

My lasercuts are ready, my rubbermount housings too... no more excuses! start welding!



Laser is so exact! Love it!... a few taps with a hammer are enough to maque everything fit perfectly. I assembled it with a few tacks and tried it on the plane to see if everything was OK



Like a charm :)



Heres the part that you can really screw things up.... It isnt weld porn at all, but not bad for a mig running CO2



Penetration on the other side (keep in mind the rubbermount bushing walls are 3mm and the core is 5mm thick)



Welding it on the inside would be sufficient... But i welded the outside and will flatten it out later with an abrasive flapdisc



Im planning to add some ribs on the inside to reinforce it a little bit more....It might be overkill but i preffer those 300 extra grams of steel in there for my peace of mind :)

[xeriotti]

This will bolt to the engine rear anchor points... Those are 10mm 8.8grade bolts.



The center reinforcing rib is ready. its so stiff i decided to go down on the thickness of the inside and outside perimeter.


Looks legit XD


Ready to start welding the perimeter and around the damper housings to close the "box"

[Kai]

Keep up the good work. This is getting interesting!

I am very curious to see what engine anchor points you will use, and how you will attach them to your ´ring mount´.

Your 40mm forward movement of the Rotax prop flange compared to the Aerovee is not something to worry about CG wise: my own 35mm did not turn out to be an issue. Another matter altogether is the standard engine cowling, which will be in for some drastic modifications. If like me you hate composite work- the best of luck!

It is obvious you have thought of something Rotax did not- accessebility to the water pump inlet albow: their own ring as good as blocks all attempts for a good hookup.

KEEP THE PHOTOS COMING!

[xeriotti]

This takes more measurements and calculations than expected.... But its on its way!!!





Im going to use the four rear anchor points... And 2 tubes connectiong each to the "ring"...

[xeriotti]

Inner and outer TIG welded perimeter ready... It forms a box, looks really strong.... Lighter than making it from aluminum, feels firm...

[13brv3]

That's a lot lighter than I would have guessed. Now for the fun part of adding the engine attachments.
Rusty