[scaleguy]

Well Trevor, [TBrum], has rocketed through his winter projects and was looking for something to do so I enlisted his help to get this project going so I can "Get-ER-Done"!

Monday night I went over to his place and we worked like madmen.

P1010229.jpg - This ARC is supplied with a 4mm thick firewall that while of some very nice quality and very hard just didn't look like enough to hold the mighty DA 85 so we added a second 1/4" plywood firewall. These, along with the supplied aluminum angle brackets were epoxied in.

P1010230.jpg - I contacted Paul Svec and had him paint up one of his new Helmut Head Pilots to match photos I provided of the helmuts the full scale pilots wear while flying the colour scheme of the Yak I chose.

P1010231.jpg - The neat cockpit kit was purchased through "Virtual R/C Cockpits" and just finishes off the hatch nicely.

[scaleguy]

OK here are some pics of the Armour Plated Engine box. The ARC/ARF comes wirh a thin piece of AL angle iron to mount inside on each side of the box. We added another piece of 1/8" AL angle iron on the outside of the box.

Last picture shows throttle servo and start of manual choke link.

[scaleguy]

Well Trev and I had a great weekend building and got quite a bit done so there will be several pics over many post for the next little while, so here goes.....

We test fitted the JTEC High Volume Pitts Inverted muffler to the engine while it was bolted to the firewall and to our dismay discovered that the muffler was going to stick out the side of the cowl approximately 1/4".

This was unacceptable to me so I bit the bullet and order a cannister, header and all the other stuff needed for mounting a can. In the Spring 2007 DA Catalogue they list the KS89VC as the cannister to use for the DA85 so I went to order that. When I talked to Jeff at DA he said they had found the the KS95V was actually performing better with the 85 so that's what I bought.

P1010224.JPG and P1010272.jpg - Now that I was putting a can in here I had to go and remove the stringers I had installed to close up the opening in the bottom of the fuse.

P1010279.jpg - Here is the KS KS95v, SS solid "?" zero drop header, 30mm to 28mm teflon reducer coupler and MTW mounting plates. The KS95v is a rear exhaust can with a 75mm diameter and a length of 300mm. The inlet is 30mm but the header is only 28mm, hence the need for the reducer coupler.

[scaleguy]

P1010281.jpg and P1010282.jpg - Trev started covering the fuse and in no time it was looking like an airplane. Man the rudders on Yaks are HUGE!

[scaleguy]

The cannister and parts arrived and we tried to get it onto the airplane.

Well DAMN if we didn't dent it all up trying to put it in. It was looking like it was not going to be able to be installed and we were contemplating going to the smaller KS89V and take a performance hit or back to the pitts with it sticking out the side of the cowl.

After some discussion and since the can was now dented and could not be returned to DA we decided to do some surgery on the plane and MAKE it fit. It was late so we called it a night.

SD_Yak_can_installed_on_mount.jpg - Treveor, the animal, just could not wait and managed to mount everything the next morning before work!

SD_Yak_Modified_can_mount.jpg - He ended up ditching the MTW plywood mounts and used a KS Comfort mount he had for the tuned pipe on his 35% Aerotech Yak 54.
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[Colyn]

Hi Jim and Trev wow do you think you needed that angle bolted the firewall/engine box?? my yak came with the same stuff but I am sure pinning is enough??? also I had the same problem with the K+S on my SD Yak scratched it and small dents trying to get it to fit, I carefully cut out three formers and cut a hole in the covering but it was too tight and I was worried about the heat so I put an MTW can on it instead as it fit in the tunnel already built in..... great job on the build..Colin.

[scaleguy]

Colin,

Which MTW can did you install?

When I talked to DA they said they were hearing from a lot of people with SD Yaks and Extras who's stock firewall was ripped out by the DA85's power so I didn't want to take any chances.

Besides the three previous Yaks I have owned have ALL been tailheavy so I figured if I have to add nose weight I might as well make it usefull weight in the form of structure not just lead.

Have you fnished and weighed yours yet?

[scaleguy]

Here are some more shots of the initial cannister install.

P1010288.jpg - Shows the "surgery" done on the front former to get can inside the tunnel. Later found out a little bit of dremeling and it would have gone in. The wood will be glued back in before aircraft is completed.

P1010290.jpg - We had to dremel out about 1/8" of plywood in a 2" area to allow clearance between the landing gear plate and the bottom, (the airframe is upside down in the picture), of the cannister. This plate is part of the fuse frame but is glued to the 4mm gear plate below it so the structure is not be compromised

P1010291.jpg - Wood shim with silicon tubing insulator to support front of cannister. Not much room left inside the tunnel with this 75mm dia. can.

[scaleguy]

And more....

P1010292.jpg - Trevor contoured the front edge of the vent opening as the stinger was exiting about an inch inside the fuse. No need to extend the stinger as there is plenty of room for the exhaust to exit without messing things up. Trev took the hardwood stringers that were cut back and mitered them to a rough curvature then smoothed everything out with his favorite item in his workshop - his dremel tool!

The standard KS Comfort-Mount uses aluminium stand-offs to support the maount but they were about 1/8" to long so Trev fashioned some up with some dowel.

P1010293.jpg - Lots of room for on either side of the cannister for air to exit the cowl.

P1010295.jpg - Completed exhaust area after painting and covering.

[scaleguy]

After we got the cannister permanently mounted using some Permatex Ultra Copper as a seal for the header to engine exhaust flange Trevor finished the last bitt of covering on the fuse and mounted the main gear..

P1010297.jpg - Forgot to mention earlier when talking about the "armoured" engine box that we also laminated an extra 3/32" plywood doubler on the inside of the engine box, from the firewall all the way back to the front of the wing tube, You can see the lightening holes Trev cut in in the upper left of the photo.