tschuy

My Feedback: (1)

Ditto on the covering job! Very nice!

KaP2011

My Feedback: (17)

It came out real nice. Good job.

larscato

Hi guys. Im well into my us60 build now and everything seems to come out ok. Today I started working on the firewall but I just cant figure out what the manual tries to tell me regarding cutting down the firewall for a 2 stroke engine.I will be using an os 75 engine on it. The firewall fits the nose of the plane perfectly as it is and if I cut it I will have to pry the fuselage together in the front to mate with the firewall. Can someone please explain? Also, when I turned the fuselage right side up after gluing it I noticed that the stab base is slightly tilted in relation to the fuse even tough it is fully seated against f6 and f6 is fully seated against the balsa triangles on the bottom of the fuse.question is if the fuse has the right angle or the stab base is

ochsnm00

I am guessing that the firewall for the 4 cycle is wider because it is set farther back. The width of the 2 cycle firewall probably needs to be cut down slightly. I think the fus front is tapered so you have to pull it together to the firewall. Does the bottom view of the fus. show a forward taper? Could you show that shot of the plan not covered by the plywood? The fus. twist probably happened due to differences in the wood. You just have to deal with it.

larscato

In theory the firewall needs to be bigger if the nr4 firewall spacers are used because the fuselage is wider the further back you get. however, the firewall fits snuggly between the fuselage sides even with the nr2 spacers for 2 stroke engine installed so I just dont get why I should make the firewall narrower and then force the fuse sides to mate with it..?

larscato

In theory the firewall needs to be bigger if the nr4 firewall spacers are used because the fuselage is wider the further back you get. however, the firewall fits snuggly between the fuselage sides even with the nr2 spacers for 2 stroke engine installed so I just dont get why I should make the firewall narrower and then force the fuse sides to mate with it..?

jrf

My Feedback: (551)

To maintain the smooth curve to the spinner. If you don't mind the bulges that will cause behind the spinner, leave it as is.

Jim

ochsnm00

Did you look at the fus. bottom view as I suggested? Do the fus. sides narrow toward the nose? You want to build this great plane to the plans, right?

ochsnm00

I just looked at the plan on Outerzone the fus. is narrower at F! than F2.

larscato

thanx guys. I will cut the firewall down then. It makes sense to make a smooth curve down to the spinner as jrf said. The reason it just seems a bit odd is that the plans show the firewall at least 2,5-3 mm narrower than the 4 cycle firewall and it requires a great deal of force to pry the rather stiff fuselage sides together to mate with the firewall.

Calvinman

Hi larscato,

I am wondering if the difference is not to make the plane balance better, a four stroke being heavier will be closer in while a two stroke being lighter will need to be further out? If this is the case I would leave well enough alone unless you have a means to take off the correct amount evenly from both sides of the firewall.

Do your fuse front top and bottom fit well now and if so will you have to also shave these down. I have only experience with the US40 and it incorporates the differences by using different inner fuse side extensions for the proper setback. An aluminum spinner will make up for the difference in weight I would think.

Just make sure the 2 stroke is not longer than the four stroke, if it is then your upper and lower chin blocks may be to short, even so you can glue on some extensions.

Calvi

I just went back and looked at your pics again, it sure looks good to me. I like your glue fillets, I like to do the same all the way back to the rear of the wing saddle.

larscato

I will have to shave of the top and bottom of the firewall to blend with the top and bottom of the fuse. The thing that confuses me is the fact that the manual tells me to shave of the with of the firewall when using a 2 stroke engine even though the firewall slides right in as it is. I have used the correct spacers and the with of the fuselage is set by the top and bottom. 3 things could be wrong here. 1: I have made a mistake earlier in the fuselage build that im not aware of, 2: there is something wrong in the manual or 3: Im just plain stupid. My bet is on the last one...

jrf

My Feedback: (551)

Double post.

jrf

My Feedback: (551)

The important part is to follow the outline of the top view of the fuselage shown on the plans. Yes, it can be difficult to bend the sides in. Soaking them with water/alcohol first helps.

Calvinman

is right thrust built into the fuse? and if so is yours correct to the plans?

larscato

Yep. Right thrust is fine. Cant go wrong on that one when the firewall spacers are installed.

Calvinman

well I would just let it go then, sand the top and bottom to match and or slightly gough the chin and nose blocks.

Calvi

ochsnm00

With the rear carb 4 cycles always need to be set back. Not only because they are longer but because you need room for the throttle linkage.

Calvinman

Good point oshsnm00, I never thought of that.

busted2props

My Feedback: (9)

count me in as Ultra Sport Brotherhood..?

larscato

thanx for all the input guys. Firewall is in and it came out nice. Yesterday I glued the turtledeck formers and stringers into place and started working on the sheeting. Im wondering on how to do this because if I lay the turtledeck sheeting flush with the bottom of the formers it doesent line up with the fuselage side and I will have to sand the fuselage side down for a nice transition. If I edge glue the turtledeck sheeting to the top of the fuselage sheeting making them flush the turtledeck sheeting will not touch the former at the bottom. The manual tells me to glue the bottom of the sheeting first. Do they mean edge gluing it flush with the fuselage sheeting?

KaP2011

My Feedback: (17)

Yes, edge glue it flush with the side sheeting. Once it is glued in place, then wet it, let it sit for a few minutes to soak in and soften the wood, then gently pull it into place and glue it to the formers.

larscato

thanx

jrf

My Feedback: (551)

No, that is not correct. The sheeting should be glued to the formers, leaving a part of the sides to be sanded off for a nice smooth transition. If you glue the sheeting to the edge of the sides you will get an obvious transition line.

Jim

larscato

Ok? I dont see why the transition line should be more obvious by doing that but I would like to be able to glue the sheeting to the former all the way around