Grant's PA-18 Project

Grant · Mar 22, 2008

I figured I would start a thread about my leap of faith into the experimental category. I purchased a spraker fuselage from a guy in CO and went out and picked it up. It was in need of a little adjustment.

I was able to get it in the basement at the house and I have a pretty good area to work for the time being. The fuselage is, for the most part finish welded except for the firewall and tailpost. I will need to add all the fittings and get it ready for epoxy coat. My plan is to have that much done this year. I have cut the tubes for the rudder pedals and will weld them up as soon as I can.

As for the adjustment that the fuselage needed:
I have since removed the short door pillars and forward windscreen v-brace to correct the problem of the upper deck being too low in the front.

Steve Pierce · Mar 23, 2008

Great Grant, one problem I see, not enough clutter in your work area. :lol: That will change. :wink:

Bill Rusk · Mar 23, 2008

Grant

Congratulations. I look forward to following your progress. As I am sure you are aware, Christian Sturm Bugs66 has also been doing exactly the same thing and has a lot of info on his site.

http://www.supercubproject.com

Welcome to the club.

Bill

Grant · Mar 23, 2008

Me and one other guy here have a question about the best way to resolve the tailpost problem we have. In the picture below you can see the tail post is just tacked between the upper and lower longerons.

I am assuming the right thing to do is to remove the tailpost and profile the upper and lower longerons to fit the tailpost properly. Are we missing something or was this just built wrong to begin with?

Cub junkie · Mar 23, 2008

Normally the longeron centerlines line up with the outside of the 7/8" tailpost on a Cub. What you are showing in the pics. needs to be addressed this way and there appears to be enough material to remove the tailpost and do just that. Be careful if you cut that out, It's a lot easier to cut out than to add.

DW · Mar 23, 2008

They should be cut loose and saddled into the tailpost with longerons centered on tailpost side with no open end.

Dennis

Marty57 · Mar 24, 2008

Grant,
I sent you a pm with a link to pictures of the process I used on my 2+2 with stock tail post and jack screw tower.

Marty

Grant · Mar 24, 2008

FIREWALL MEASUREMENTS -

What do you guys have for the center to center measurements for the bolt holes horizontally and vertically.

The Piper and the Northland prints are different. Could someone measure these for me...To clarify I am looking for the horizontal measurement and the vertical measurements. I am assuming the top horizontal distance and the bottom horizontal distance are the same.

DW · Mar 24, 2008

Grant

Mine measures the same as the northland drawing 18 3/8 vert. & 18 3/4 horz. I have a 1955 pa18

Dennis

Grant · Mar 24, 2008

I was wrong, I must have misread the piper print.

Jim Miller · Mar 29, 2008

Tailpost

Grant
I just finished fixing my Spraker tailpost problem. If you tailpost is in proper relationship now (That is parallel with firewall and level left to right ) then measure a 45 degree lines in the upper and lower longerons keeping in mine that when squeezed together the centerlines of all four longerons should line up with the edge of the 7/8 inch tailpost tube. After cutting I used the two fittings (Upper horz and lower front tailwheel bracket) to determine how the tubes should be squeezed together. I tacked both in place in their correct final position to hold the longerons together. I would cut the 45's a little long and use dremel for final trim. After tailpost is re tacked heat longerons and with small hammer tap them down to form to post for final welding. Hope this makes sense. Posting photo's to web is not my strong suit.

Jim Miller (Tennessee)

Grant · Mar 30, 2008

UPDATE - WAITING ON PARTS

I have some parts on the way and have just about decided on a welder. I need to finish up the fwd door pillar replacement and V brace that I removed due to the top deck issues.

Next will be correcting the tailpost problem.

I think I need a shop stool so I can sit and wait for my parts instead of stand

Snert · Mar 30, 2008

Or lessons from the Maytag repairman. Am I missing something?(probably) You buy a tack welded fuselage and that's how they finish the tail post? I wish my customers were that forgiving.

Grant · Mar 30, 2008

Yeah the tail post is a little bit of a disappointment. It's completely correctable though. Just time and effort.

behindpropellers · Mar 30, 2008

Grant said:
Yeah the tail post is a little bit of a disappointment. It's completely correctable though. Just time and effort.

Doing better than me...!!

Keep up the good work!

Worked today and yesterday...need to go dust off the cub and get back to work....grr!!

Tim

Grant · Mar 31, 2008

I finished the new door posts and tacked them in place. I was able to get one of the sides to the v-brace done too. I picked up a little Miller Maxstar 150 tig machine....It is going to take some getting used to but I think I'll like it.

DW · Mar 31, 2008

Grant
In your last photo it looks like there is a frame tube running threw the middle of the door/window opening. going to be hard to get in and out.

Cub junkie · Mar 31, 2008

DW said:
Grant
In your last photo it looks like there is a frame tube running threw the middle of the door/window opening. going to be hard to get in and out.

That tube don't need to come out for quite a while. Tell us more about that TIG machine when you get a chance Grant.

Snert · Apr 1, 2008

Grant
You have probably done as much homework on your project as anybody on this site. What is it going to look like when it's done? Engine,prop,wings,suspension,mods?

Steve Pierce · Apr 1, 2008

Grant, Have you spoken with Spraker? He used to advertise here a lot. I wondered if your fuselage was the norm?

Grant · Apr 1, 2008

Steve, I have not spoken to him - I did not buy it directly from him. If I had bought it from him I would be a little mad about the tail post but that's all. I have talked to him in the past and he seemed to think he had the fuselages pretty dialed in. I think the problem with this one was the welding and not the fuselage. The only thing I would complain about would be the tailpost. But it is experimental so a little work and a little time will fix that.

Snert, Here is the plan....

Finish the fuselage this year through coating (Epoxy or powder?) with float fittings and all the smart/safety mods
Put it on 3" extended gear with bungees
31 AK Bushwheels with a 3200 scott tailwheel
Atlee safety cables (I'll buy them)

Standard wings - Planning to buy used when one of you guys upgrade

Whatever tanks come in the wings I'll use
for now standard fuel system but may change to the cc system.
160 HP (Used out of a salvage airplane)
borer Prop (New or used...I dont think many people sell them after they get them)
Simple instruments on the small panel or maybe the one that is a bit taller but not a huge panel.
wood floorboards
aluminum interior
standard D windows
Not sure what covering process I'll use - any advice?
anything I forgot?

Cub Junkie,
It is a Miller maxstar 150. It is an inverter type and is pretty small. It has a finger control which I find clumsy but it works for tacking. It is DC only so no aluminum. I bought it locally so it was a little bit more than ebay when you add tax but I like knowing I can call the guy down the street. I set it on 65 amps and use the finger control to adjust. I picked up a 40 Cu.Ft. bottle. I think it must be broken because the welds I did when practicing are not what they look like in the movies.......

Cub junkie · Apr 1, 2008

Keep practicing Grant. Those welds will improve. Does that thing have a provision for a foot control? The new inverter machines are unique. What once was housed in a huge cabinet is now in a box just slightly bigger than a 12 pack of beverages. I like the Miller Dynasty 200DX, if I was buying that's what it would be, not cheap though. I have a Miller Syncro-wave 351, more welder than I will ever need but the square wave is nice for welding aluminum. The 200 DX is even nicer in that respect.

behindpropellers · Apr 1, 2008

Grant-

A little advice here:

1. Stop working on the airframe.
2. Buy two of these http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=32915
3. Build yourself a rotisserie.
4. Install plane on new rotisserie and get working.

The welding you do to build the rotisserie will make you a better welder (good practice) and it will make it 10x easier to work on your plane. Check out my link below, for ideas.

Tim

Grant · Apr 7, 2008

Tailpost has been corrected but not welded yet. I will close up the tubes later.

I thought some of you would like to see how I am leveling the fuselage. This works great. It is a tool stand from northern Tool and a left over leveling jack from my famous camper....

Since my last post I have returned the welder. I just was not happy with it. I think I will buy a nicer one later. I can get along without it for a little longer but not much. Thanks for the support and advice. I will set up the rotisserie as soon as I start welding again.

Cub junkie · Apr 7, 2008

Much better on that tailpost fit Grant. Send Spraker a photo, he could learn from this. If you end up Ox/acet on the welding the Meco Midget torch is awesome.

Fabman · Apr 8, 2008

Hey Grant,

Could you post a picture from a differend angle of your tail post, something does'nt look right?

Grant · Apr 8, 2008

uh oh.....

what looks funny?

Cub junkie · Apr 8, 2008

From the angle shown maybe the diagonels not extending into the corner of the tail post /longerons ?

Grant · Apr 8, 2008

you're right.....More time and effort but I will fix it. Thanks for the find..

gander · Apr 9, 2008

You may want to hold off with the epoxy coating until you have the interior and all other pieces fit for final install and then paint them all at one time. Ideas change, may need some additional tabs,ect.

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