RE: 4*120 Build Thread
 

Waiting for some pics. On the tool board on the wall of your shop there's an outline of a LARGE wrench. Do you wrench on trucks or floating rear-ends by chance? Wait, wait, don't tell me....It's a fly wheel wrench for a Briggs....probably a racing engine?

RE: 4*120 Build Thread
 

Actually, Its a Clutch wrench for a racing Go Kart Clutch. Look closely and you will see me in those 8x10 pics. I raced them for 15 years. ALmost broke me too.

:)

RE: 4*120 Build Thread
 

Heres a few pics....

RE: 4*120 Build Thread
 

well dangit.....

RE: 4*120 Build Thread
 

last 2

RE: 4*120 Build Thread
 

Hey do you think one of those engines can swing a prop?will it fit the 120?

RE: 4*120 Build Thread
 

I guess you know the guys at CKI? "I mean, HEY, how fast do ya wanna go"? When I worked at RCR we'd go down there and visit with Louis and Stan and them.

RE: 4*120 Build Thread
 

Yep, Thats a Methanol burner, 5HP that puts out 12 HP at 6950 RPPM. New that motor is $1500 and $380 to freshen it up (every eight races) Yea, I know the guys at CKI.

My Cousin builds the engines on the 31 car at RCR. He has been there about 12 years, they were just on speed channel and they beat Hendrick Motosports in the Clevite Engine build Championships.

Im gonna head down and do some sanding.

Later

RE: 4*120 Build Thread
 

ALRIGHT!!
I'm back in the saddle. I got downstairs today and did a little work.

I decided to go ahead and cut out the stock firewall and move it back. Had to fab a new firewall.

The firewall needs to be 4.25" wide. Even though the fuse is only 4" wide inside--you need an extra 1/8" on each side to "key" it into the fuselage side doublers.

It is 5 and 3/8" tall (5 3/8" )

I didn't have enough hard ply to make a firewall out of 1/4" ply. So, I improvised. I made my firewall from 1/4" lite-ply and then doubled it up for a total thickness of 1/2".

I decided to build in some right thrust with this firewall. The factory firewall doesn't have any right thrust in it, and since I'm using a bigger engine--and I had to make a new firewall anyway--might as well build in some right thrust.

I measured back on the left side 1 and 1/2"--(1 1/2" )--and made a mark where the FRONT of the new firewall would set. Then I measured back on the right side and made a mark at 1 and 9/16"--(1 9/16" ). What this does is angle the firewall off too the right. So, I've created 1/16" offset in the distance of the firewall--4".

Now, I have my lines marked on the sides of the fuse where the front of the firewall will set. And my firewall is 1/2" thick. I just made another mark 1/2" behind the first marks. I've got my firewall layed out.

Now, I took a razor saw and cut through the fuselage side doublers untill I hit the fuselage sides. I needed to remove the doubler where the firewall would set. This allows the new firewall to be "keyed" into the fuselage sides. Just like the stock firewall. The doublers are 1/8" thick on each side. Thats why the firewall is 1/4" oversized for the spacing inside the fuse. By making the firewall 1/8" bigger on both sides and then cutting through the doublers--I've got my firewall locked into place between the fuse sides and it can't move forward because it's resting up against 1/8" of lite ply on both sides.

The pics will make this clear as day. I hope I'm explaing this clearly.

I've got some pics here of the glueing procedure. I've used a handfull of rubberbands to act as clamps. Also got a couple bar clamps on there as well.

The first pic is a shot looking from the front. If you look on both sides--you can see where the old firewall was cut out and then just sanded flat with the sides of the fuse.

The second pic is a shot from the back--inside the fuse. This just shows where the new firewall is sitting.

The third and fourth pics are just waiting for the glue to set. Notice how I've cut the fuse side doublers out to key the firewall in.

Pics:

RE: 4*120 Build Thread
 

Alright. Got the new firewall in. Time to set the engine in there and check the centerline of the prop hub/crankshaft.

Keep in mind that your looking at the FRONT of the plane in these pics--so left and right are backwards.

I've got 1/16" offset in the firewall. The engine needs to be mounted slightly to the left to compensate for the offset. But, the centerline of the crankshaft needs to end up exactly centered between the sides of the fuse.

This is trail and error. I'm just using a clamp to hold the engine in place while I take measurements at the crankshaft to get it exactly centered between the fuse sides.

When it's all done--the LEFT side of the engine is 3/8" away from the side of the fuse. The RIGHT side is a little over 5/8" away from the side.

So, the engine is offset to the left, and the firewall is angled to the right. Prop lines up perfect in the centerline of the fuse. Got my fingers crossed that I didn't just totally screw up and build in too much right thrust.[sm=bananahead.gif]

You can really see the offset and how much the engine is fudged over to the left in the first pic. Look closely at the side of the engine mount. Notice how much closer to the side of the fuse that the left side is. Notice how the right side is pretty far away from the side when compared to the opposite side.

The pics with the tape measure are a bit fuzzy. Sorry for the poor quality.

RE: 4*120 Build Thread
 

I gotta get back after it. Been sitting here pounding on the keyboard and stuffing my face for 1/2 hour.

I need to add some bracing at the landing gear mount. But, I can't do that untill my wing is mounted and the dowel holes are drilled. I can't add a bunch of bracing to the LG mount and then block my access for drilling the holes in the F2D former and the LE of the wing.

I made a dummy mistake. I made my servo trays for my wings on the TOP of the wings.[X(]

I just wasn't paying attention to top and bottom when I put the servo trays in. Oh well, at least I did it the same on both wings. Would have really sucked if I'd put the servo tray on the top of the left wing and the bottom of the right wing.

I'm not hacking this out. The trays are glued firmly to the rear spars and the wing ribs.

I guess this will be the first plane that I've ever seen with wing servos on the top of the wing panels. I may fab up a little fairing to streamline the air going over the servos. I could cut the back half off a wheel pant and use the pointed end as a fairing. Just glue it down to the wing or rig up a couple blocks on the wing and attach the fairings with some small screws. That way, I've got access to my servo, horn, and servo screws.

I'm a dumb@$$. Can't believe I did this. Rookie mistake for a guy with 30 kits under his belt.:eek:

RE: 4*120 Build Thread
 

The firewall work makes up for the mistake on the other.

nice work

RE: 4*120 Build Thread
 

If he's been there that long it must be Greg G.

RE: 4*120 Build Thread
 

Bingo Bingo :D

RE: 4*120 Build Thread
 

I been workin' hard tonight.[8D]

I got my wings panels joined.

I got my dowels put in the LE of the wing.

I got F2D drilled out for the for the dowels and added a piece of 3/8" hard plywood to the front of F2D. This extra 3/8" of ply will just give a bit more meat for the dowels to set in when the wing is bolted on.

I got some bracing put around the LG block. I just added a piece of 1/4" ply to the FRONT of the LG block. I'm going to pin this brace into the front of the LG block with a few 1/8" pins.

I'll finish my LG block and brace with some tri-stock and epoxy.

EDIT:

11:35pm----I'm going to start working on the wing hold-down blocks. The wing lines up perfectly. I made a centerline mark on the fuse at the front where the dowels go in. Made another mark on the fuse at the back of the wing saddle. My wing center joint lines up perfect with the mark at the front. The wing sits in the saddle nice and when I align the center joint of the wing at the TE with the CL mark on the fuse--it's all lined up pefectly.

Measuring from the TE of each wingtip--and back to the CL of the tail of the fuse measures exactly 52 and 5/8" (52 5/8" ) on both sides. [8D]

That means this baby is as straight as they get. I'm gettin' the hang of this kit buildin' stuff.:D

Time to smear some epoxy. More pics tomorrow.

Pics:

RE: 4*120 Build Thread
 

Why not take a dremel with a sanding drum,cut some of the airl servo plate out then sand the rest down to get the plate and some of the weight out then make some new ones to put on the bottom,quick and easy and they will be where theey belong.

RE: 4*120 Build Thread
 

Who says they belong on the bottom?[sm=tongue.gif]

I could cut them out. I can, but I don't want too.

I still got time. I need to think on it for awhile.

RE: 4*120 Build Thread
 

Here's some pics of the wing mounted to the fuse.

I installed the wing hold-down blocks in the back of the saddle last night. I followed the directions [X(] (I know, I know) and just drilled and tapped the hardwood blocks to 1/4--20 thread.

I've never been very trusting of threads in a wood block to keep the wing attached during flight. I'm going to have to put in a blind nut--or I'll always be worried. I'll have to shave a bit of meat off one side of the blind nuts to get them in because they will be hitting the fuse sides if I don't.

Also a pic of my favorite helper holding my engine for the plane.:D

RE: 4*120 Build Thread
 

I'm working on the horizontal stab now.

First thing--notice in the first pic that my plans are laid out and the excess plans are drooped over the edge of the table. Some guys will just fold the plans untill they fit on the table and then lay the wax paper over the top. Thats okay, untill you slip or get greedy with the CA bottle and soak the snot out of one of your joints.[X(] The CA soaks all the way through the wax paper and your plans end up glued together. Kinda hard to finish the model when your plans are glued together.;)

I've laid my plans out and taped them to the table with some low-tack masking tape. Then place the wax paper over the top and taped it down as well.

I'm just pinning the LE and TE of the stab. All the small sticks are just cut and sanded to fit. Then glued in free-hand.

Got my favorite helper on the glue bottle. Didn't take her long to figure out that ya need to keep your head outta the way of the fumes.[&:]

Pics:

RE: 4*120 Build Thread
 

Least you got help~!

:)

RE: 4*120 Build Thread
 

I got the stab framed up. Pulled it off the board and removed all the plans and wax paper. I'm putting the 1/16" sheeting on now.

Got glue?

Got saw?

Lets frame this bugger up and go fly it Dad!!:D

I'll have her soloed next year---probably start her out on a 3 channel electric thats drastically low on power and really slow.[8D]

RE: 4*120 Build Thread
 

I pounded it out tonight, to be honest, I got the burnouts bad over the course of the last 2 days. Tonight I wanted to work on the fun stuff of the plane, THE MODS!

I headed downstairs with the looks in my head of RC universe members Damifino and Mr70ss' modifications, A psychedelic racer-pylon looking plane. To me, the four star in its factory stages looks like an vintage cessna for some reason. From its 4x too large canopy to the straight cut, not to mention flat fuselage.

I didnt cut a rib off each wing as anticipated. Im putting a 25cc gasser on this plane and I wanted all 1200+ inches of wing to be there for it. I did however move the cockpit rearward to remove some of that vintage look and persuade an onlooker to be reminded of an Edge or something along that line, extra, etc.

I moved the cockpit a full 4.5 inches, trashed the stock headrest and used what WAS the 3rd former as the new headrest. I rolled the top deck which was flat as a Montana highway into a nice, freeflowing angle down to the firewall . This alone made the plane look great. I fabricated formers for the top deck and spaced them accordingly to accomodate the falling angle I was trying get.

I will however have to add some filler as one of my formers did not come off as tall as I needed to. It gave my angle a low spot in the center and if you look, youll see it. Noting a swipe of good ol puddy wont fix. I also rounded the Stab control services to help with modernizing it a bit more. Lastly ( for tonight) I hacked the crap out of the cropduster style canopy and have to admit, I may hack it a little more!

Im bushed, Heres a few pics of tonights work, notice my alpha trainer how the size compare to the biggun................

RE: 4*120 Build Thread
 

I got the vertical stab and rudder done tonight. I still need to sand the LE round.

This is redneck scratch building!! Makin' it up as I go along!![sm=stupid.gif]

I built the vertical stab per plans, but then it got crazy. I wanted a counter-balance, so I just threw down some 3/8"x1/4" stock and started framing. It's 3/8" wide because the stab is 3/8" by the time you get it sheeted. I wanted the rudder to be the same thickness.

Counterbalance is 2 and 3/4" (2 3/4" ) I don't even know what the rest of the measurements are. I just framed it up and then sanded it.

Bottom of the rudder--on the hingeline is a piece of 3/8" hard ply. Thats my hard point for the control horn.

Bottom of the rudder--at the TE is a piece of 3/8" balsa buried in the corner. I'll sand the TE of the rudder to a rounded shape later--so I'll need this piece in there to support it when I get it all sanded down to almost nothing on the bottom and the TE.

I was using a very technical building philosophy here. The tried and true, "That's about right." method.:D

RE: 4*120 Build Thread
 

I like to use the make it up as you go along route,always seem to work out better that way,Oh I start with a list and a few drawings but they go by the way side early on.Things just look different as you build.

RE: 4*120 Build Thread
 

:D lookin good