South Jersey Skybolt :: A Radial Engined Biplane

More... The Radical Radial Fuselage.

March 11, 2008
Scaring yourself...
into building it right....

Never get lulled into thinking that... it's a little off here, but, that's OK.

It's never OK to allow something to be even a little off when you know it isn't right. I slapped myself when I thought those words. How could I even think that, let alone go ahead and commit the act ??

It happend one cold rainy night... the lights were flickering, cats screeching in the distance, the howling of a dog. I was burning the midnight oil working on the Skybolt. Pencil in one hand, drawings in the other, straight edge in the other. Wait... what the hell am I doing with another hand !?

Anyways... I was concentrating on squaring up the two table tops, measuring and marking the lines and making sure that it all stayed aligned. Not a lot to write about it. You look at the plans, mark your dimensions then draw them on the, as in my case, MDF boards.

It's all square and my lines connect the points that I've drawn on the board... no problem. OK... I get to station 51, where the longerons need to be heated and bent in to meet the tailpost, the left side of the fuselage... points all line up as I draw my line from station 51 to station 168, the tailpost. nice... Start connecting the dots on the right side of the fuselage, everything lines up as I pass station 85. I have an 8'x3"x1" square metal tube that I use as a straight edge. I line this up with the line coming out from station 88 and... huh ? (blink a few times, thinking that the flickering light is playing tricks on me) But... huh ??? If I extend that line off of station 88 it'll fall on station 169.5. I go to look at my prints again. Yep.. I was right. There ain't no stinkin' station 169.5, something must be wrong!

Rubbing my eyes, and tightening the bulb in it's socket so that it'd stop flickering, I checked that "extended line" again. Sure enough... the end of it lands 169.5 inches from station 0.o . DAMN ! I checked the measurements again and took the straight edge only to commit the same sin that I had previously commited... a line that lands at station 169.5. So I sat and thought about it a little, then a little more... hell why not, so I thought about it a little more. Went back and made sure that all the measurements were good and they were.

What to do ? what to do ? When I took a look at that line again, I saw that I could skew it a little to the left, just a smidge, and it'll land on the point that I wanted it too, you know... station 168.o. That wouldn't be a bad thing, would it ? Would it ?!

I got to thinking about that statement. What's scary, other than where that third hand came from, was that the line for the upper longeron, that I drew, was a little off, and I was thinking that it would be acceptable to just smidge it over a little. Just the thought of me thinking that, that, was acceptable scared the crap out of me.

I had to stop at that point. I'm all for a good black and white Bela Laugosi horror flix, but this was getting creepy.

I'll come back to this tomorrow night, a little removed from the horrors of tonight. Maybe when the sun is still high in the sky... it'll make more sense to me.

March 12, 2008

Follow up to the night before...

Came back to the jig pattern during the daylight hours today. Sanded off all my marks from station 51.o on back. Took a different approach to making sure my points were correct and that my measurements were square with the front. Funny how the light of day seems to wipe the scariest of nightmares from our minds.

Whatever I did, that I didn't do the night before, was working. No problem connecting all the dots. Finished drawing the pattern on the MDF... the jig layout was now ready for me to install the jigging blocks for the longerons.

By the way... those screeching cats... they were mine. I locked them in the upstairs bedroom... they were bugging the hell outta me... and the dog howling... I just made that up. My dog Ammo, hardly makes a sound. About the only truth to what I wrote was the thing about me "thinking" it was OK to allow "a little off," oh yeah... it was cold too. Still wondering where that helpful hand came from.

March 17, 2008
     Straight as an arrow... ???
          the point on the tip...
                        was as straight as I got

One of the things I feared most... extreme warping of the longeron, or so I thought.

Saturday I went out and purchased wire, turnbuckles and a pound of 2" drywall screws. I was getting ready to put those two longerons in the top jig fixture and start tacking the cross pieces in place so that I could start welding up my fuselage.

The MDF table top went in place real nice. Put all the jigging blocks in place and took the first fuselage side, turn it upside down and said... huh ???? Warpage, as they say in the business. Could a few tack welds make the top longeron "cup" like that ?

I picked up the other side and flipped it on it back.... same thing. From Station 0.o to Station 168.o there was about a 1/2" cup in the upper longerons. Ahhh... this stuff happens, so I went about doing what yer suppose to do... heat it on the side that you want it to bend towards. So I heated the four clusters on the top of one of the longerons... and heated... and heated... and heated... clamped and heated... and heated... and well, you get the picture. All my heating did nothing to the "cup" that I had.

Had my suspicions about what was wrong but threw the question to the guys on the biplane forum. They had questions about what I was trying to describe. Neil, from Monroe, LA, offered to speak to me about it over the phone.

I needed to know exactly what the fuselage side jig looked like before I could speak to Neil, or answer any of the questions that the guys on the forum were asking.

Got home from Denise's around 12:45AM on Monday morning and it was a little too late to be unscrewing the MDF tops that I had laid over top of the tables that I still had the lines on for the fuselage side (don't know how I could be so lucky there.) Tossed and turned until about 2AM trying to think this thing through.

Got home from work. Ran the pup. Grabbed a bite to eat then headed out to the garage workshop to see what was underneath that MDF.

Took some twine and "snapped" a line from station 0.o to 168.o. Used the straight line from station 0.o to 51.o as my "straight edge." That damn twine is so hairy you could have a line 3/4" inch off and it'd look OK. Went into the house and grabbed some black sewing thread. Snapped that line again and saw that station 168.o was 1/2" higher than station 51.o. Huh ????? Now I know that I checked that line three or four times with my eight foot straight edge... but I guess that just wasn't good enough.

The straight "as an arrow line" lookin' more like the "V" on the arrow head. Not a good thing, unless you're bow hunting.

Look, if you're building your fuselage jigs... if you don't have one, go out and buy a chalk line (blue chalk.) Snap your line using that and you'll never need to experience the crap that I'm going through right now. Don't know why I've never read that before, anywhere. Consider me the inventor of using a chalk line when building your jig.

I called Neil after seeing what demons I discovered and talked through a plan of action with him. Pretty simple, actually.

I'll make sure that the top longeron is straight, as it was always suppose to be, and use that as my base line. Re-block the jig. Cut the tack welds on the bottom longeron aft of station 51.o. Set the fuselage frame back in the jig and allow the angled tubes to fall into place on the bottom longeron. Found that five of the eight angled tubes were fine. One of the three remaining tubes could be cut down and used again. The remaining two had to be scrapped. Not bad, considering. I thought I would need to remake the entire fuselage side. Just dodged that bullet.

I still need to cut and tack those tubes into place. The next fuselage side is the one that I heated the hell outta. Wonder what lies in store for me there ?

YIKES !

By the way... thanks for your help, Neil.

March 19, 2008
Snapping red lines...
am I sure everything's straight ?

Back out to the garage workshop (sounds like I have a lot of working space when I keep talking about the "garage workshop" and the "workshop in the basement... that ain't the case) to set about fixin' what apparantly I "broke."

Thought that I would only need to replace two tubes, cut one down and tack into place. Thinking and reality are sometimes two different beasts.

When I cleared the tables of all the clutter and started the actual work, I saw that in order to notch those tubes I needed to move a few of one that I had left tacked down; more tack welds to break. I didn't waste much time thinking about it... I just went ahead an did it. I've measured cut and notched quite a few tubes up to this point and I knew what I needed in order to get it done, and done right. Why waste time thinking about something you already know ?

But wait... I need to snap that chalk line before I do anything. Quick found the chalk line, (by the way, I can remember where I placed my chalk line from a year ago, but something I've set down yesterday I can't seem to find. Short term memory loss, I guess.) which, by the way, was red. Still worked. Gave me that straight line that I was looking for and this time it was dead on.

Anywho...
I spent the night listening to some good old rock and roll on WMGK (earlier I had sent Ray Koob, one of the Deejays, an email) he actually acknowledged it over the airwaves.) while making the changes to the airframe. Listening tonight, no different than any other night. I enjoy listening to Ray interject a little history inbeteen the songs.

Well, a little over three hours passed and the side was ready to be tack welded... again. I'll do that first thing tomorrow and then set about getting the second side squared away so I can set it in the fuselage top jig and start measuring and cutting and notching and tack welding the cross tubes in place. I'm actually not looking forward to this second side. It's the side that I heated and heated and heated and heated and... May be a tough nut to crack. I'll keep you posted on it.

March 20, 2008
Put one foot in back of the other...
and soon you'll be doing things again....ain.... ain

After tack welding up the first fuselage side, for the second time, I took a look at the second fuselage side... you know, the one that I heated the hell outta the first time trying to fix a "cup" that wouldn't get fixed no matter what amount of heat you applied to it.

It was bound to happen. One of the learning things that we do this for. (not on my next airplane, he says...)

Could I correct all those bends by applying heat to them ? Yeah... but how much time would it take ? And would it be to the standards that I would want ? Naahhh... probably not. With that thought firmly in place I took my Dremel tool, with the cut-off wheel, and started cutting the tacks off the top longeron.

I have the tubing to replace the screwed up longeron. I'll need to go back and take an inventory of the remaining tubing to make sure that I have enough to measure, cut and notch all the cross pieces. As it stands, my second fuselage side lays on the jig table awaiting it's top longeron. I'll continue working on that this Saturday.

I should have this tacked up by the end of this weekend... we'll, that might be wishful thinking. It's Easter and I have things to do. Let's say I'll have it ready by next weekend, for sure.

Could I have done anything different to have avoided this ? Playing Monday morning quaterback... I don't really see where I could have done anything different other than using that chalk line. I thought that an eight foot straight edge would have been the ticket. I took my time by overlaying the first line with half of the eight foot straight edge. I would have thought that I would have been just about dead on. I was wrong.

Do yourself a big favor and lay your fuselage jig out using a chalk line. Saves about 10 hours worth of back stepping, back paddling... whatever you want to call it.

Still more to come... click here to read about it.