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  #1  
Old 10-03-2021, 05:05 AM
Desert Rat Desert Rat is online now
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 680
Angry Dangitydarnheck!!!

I'm really mad at myself, and frankly, a little embarrassed, but I know that I always appreciate it when people post mistakes, so that I can be forewarned if I haven't gotten to that section yet, so here goes.

Located the roll bar / windshield frame this weekend; The mounting hardware for this weldment consist of an AN3 & AN4 bolt on each side through the weldment foot, through the F-721 aft canopy deck and as close to the main longerons as humanly possible without actually touching them.

You accomplish this by laying out locations on the deck, then pilot drilling #40. Theres' lots of match drilling and up sizing after that

The dimension for the front hole (AN3) is a nice big easy to read 7/8" yay! No need to squint and try to get down in the weeds to find 29/32 or something equally hard to read.

In fact this is so easy, that I can likely read the scale upside down, mis-read it, and drill this pilot hole off...not a few ticks, not the width of a sharpie line, but by a full 1/8"

I noticed it almost as soon as it was done, but of course, that is exactly not soon enough. Taking a quick peek underneath, I discovered that I nailed that 6/8" wrong dimension so precisely that I now have 1/2 of a #40 hole in the edge radius of the horizontal leg of the main longeron there between the two vertical members of the center section bulkhead.

1/2 of a #40 hole is about .050. Not even enough to completely wipe out the radius on the edge of that leg, but on the other hand, There's a lot going on in that area and I don't have a good sense of what sort of loads the longerons are carrying through there what with all the structural buildup that's running every which way.

I'll obviously call Vans tomorrow, and I can see a couple of potential solutions, but mostly I'm just sharing to make myself feel better.

The other takeaway from this is that in a perfect world, if you lay out those pilot holes per print, The full size holes will miss the edges of the longerons by 1/16". There's a note on the print that says these bolts should be snuggled up to the longerons as close as possible, but 1/16" isn't much to play with for something that's being drilled through a bunch of layers by hand. In addition to the one I obviously Fubar'd, I had to pull another one inbd will a drill fixture because the pilot hole looked a little iffy. I think if I had this to do over, I'd move all those dimension inbd a fraction more to give myself a little more breathing room.

Oh yeah, I'd also do it right the first time...
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Last edited by Desert Rat : 10-03-2021 at 05:53 AM.
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  #2  
Old 10-03-2021, 06:39 AM
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rv8ch rv8ch is offline
 
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Location: LSGY
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Ouch - that looks painful. I'm sure the factory will be able to suggest a fix, and once flying, you won't think about it.

One thing I learned that might help in situations like this is to measure from both sides of where a hole will go. You sometimes find a surprise on the other side, and it helps with the "measure twice, cut once" guidance.
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  #3  
Old 10-03-2021, 07:27 AM
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DanH DanH is offline
 
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Terry, successful aircraft construction requires a certain command of profanity. Without the magic words, bad juju builds up inside a builder's head, and pretty soon nothing goes right. Skilled deployment pushes out the bad juju, and transfers it to your neighbor's attempt at lawnmower repair.

Do not be hesitant or embarrassed. No one need know the depth of your skills, as the words are most often spoken in private, or muttered well below a level audible to others.

Not to criticize, but "dangitydarnheck" is suitable for the fabrication of teddy bears or flower arrangements. Aircraft and racing vehicles require powerful expletives, as the juju is strong. Here are a few tips for effective deployment of suitable words and phrases.

Unless raised in a convent, you're already familiar with the most popular four letter words. The secret lies in matching these key words with colorful pronouns and adjectives. For example, the phrases "You dumb.." or "I'm such a stupid.." can predicate a wide variety of four letter favorites, and are particularly appropriate in the case of miss-drilled holes.

Advanced applications include preliminary phrases. For example, a loud exclamation describing female canine parentage may proceed one of the previously given pronoun examples.

Like most skills, effective builder profanity requires practice. Lock the shop doors, chuck a #30, drill a hole in your finger, and be creative!
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Last edited by DanH : 10-03-2021 at 07:29 AM.
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  #4  
Old 10-03-2021, 08:02 AM
Girraf Girraf is offline
 
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Location: Southern Maryland
Posts: 194
Default That'll buff right out

I believe there is some therapy in sharing ones happy accidents.

In all seriousness, if you can fully notch the horizontal leg of the longeron for the horizontal stab mounting area, I'd be really shocked if the factory advice is much more than blend your halfmoon.
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  #5  
Old 10-03-2021, 08:12 AM
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jcarne jcarne is offline
 
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Location: Worland, Wyoming
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Quote:
Originally Posted by DanH View Post
Terry, successful aircraft construction requires a certain command of profanity. Without the magic words, bad juju builds up inside a builder's head, and pretty soon nothing goes right. Skilled deployment pushes out the bad juju, and transfers it to your neighbor's attempt at lawnmower repair.

Do not be hesitant or embarrassed. No one need know the depth of your skills, as the words are most often spoken in private, or muttered well below a level audible to others.

Not to criticize, but "dangitydarnheck" is suitable for the fabrication of teddy bears or flower arrangements. Aircraft and racing vehicles require powerful expletives, as the juju is strong. Here are a few tips for effective deployment of suitable words and phrases.

Unless raised in a convent, you're already familiar with the most popular four letter words. The secret lies in matching these key words with colorful pronouns and adjectives. For example, the phrases "You dumb.." or "I'm such a stupid.." can predicate a wide variety of four letter favorites, and are particularly appropriate in the case of miss-drilled holes.

Advanced applications include preliminary phrases. For example, a loud exclamation describing female canine parentage may proceed one of the previously given pronoun examples.

Like most skills, effective builder profanity requires practice. Lock the shop doors, chuck a #30, drill a hole in your finger, and be creative!
Dan your legendary posts know no bounds. That one had me laughing man.

Terry, don't fret too much, I'm betting Van's has a fix for this. I did something similar on my firewall.
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  #6  
Old 10-03-2021, 08:30 AM
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wirejock wirejock is offline
 
Join Date: Oct 2005
Location: Estes Park, CO
Posts: 4,678
Default Bad Joo Joo

Quote:
Originally Posted by DanH View Post
<snip> Skilled deployment pushes out the bad juju, and transfers it to your neighbor's attempt at lawnmower repair.
<snip>
Like most skills, effective builder profanity requires practice. Lock the shop doors, chuck a #30, drill a hole in your finger, and be creative!
That was some funny $...
In my case, the neighbor will bring the lawnmower over to my shop because, I'm building an airplane!
Having drilled a finger, I can attest, there is a lot of bad Joo Joo expended.
Thanks Dan
Best of luck Terry
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  #7  
Old 10-03-2021, 10:14 AM
danny danny is offline
 
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Location: puyallup, wa
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Default Words to build by

Is there no end to the depth and volume of creative wisdom shared on this forum? If there is, I haven't seen it.
I love this place!
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  #8  
Old 10-03-2021, 11:24 AM
Desert Rat Desert Rat is online now
 
Join Date: Aug 2018
Location: Wichita KS
Posts: 680
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you guys crack me up. Thanks all.

FYI- I know it's not the end of the world. I'm going to predict that I hear "blend and use as is." But it's still frustrating make such a stupid mistake.

Worse case scenario, I think a version of the C-668 spacer thats long enough to pick up a couple of rivets on each end would be the simplest way to do a doubler in the area, but would be massive overkill from a reinforcement standpoint.

I've seen worse deviations dispositioned on brand new airplanes in the Wichita, and would also be willing to bet that there's more than a few RV's flying around with stuff in this area covered up by several layers, never to see the light of day.

I'll report back...
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  #9  
Old 10-03-2021, 10:13 PM
Scott Hersha Scott Hersha is offline
 
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Location: Cincinnati, OH
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Iíve done worse, and still came out OK. This is a bunch of funny responses - wish I had a better one, but honestly, I donít think your nicking of that longeron has sacrificed itís structural integrity. The answer may involve bridging the longeron in the area of the misaligned hole with a doubler, attached fore and aft of the affected area on the longeron nick that allows the drilled hole to be bolted right where it was drilled, and share its load with the longeron as if it was drilled right through the middle of it. This would involve drilling out a couple longeron rivets fore and aft and building a doubler that will be doubled up inboard of the longeron with extra rivets installed to make it act as one solid piece so the drilled hole for the roll bar weldment (very important) wonít know the difference. That forward bolt, a #3 as you mentioned, doesnít carry as much vertical load responsibility as the aft roll bar bolt, a #4, that is positioned right over a forward fuselage bulkhead. I think that forward bolt is mostly designed for shear load protection in the event of a nose over accident that places a shear load from a force on the top of the roll bar. The bolt can handle that. The structure it is attached to also needs to handle that. Beefing up that structure where that bolt is attached should make sure that happens.
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  #10  
Old 10-04-2021, 07:11 AM
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Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 6,290
Default

Quote:
Originally Posted by DanH View Post
Terry, successful aircraft construction requires a certain command of profanity. Without the magic words, bad juju builds up inside a builder's head, and pretty soon nothing goes right. Skilled deployment pushes out the bad juju, and transfers it to your neighbor's attempt at lawnmower repair.

Do not be hesitant or embarrassed. No one need know the depth of your skills, as the words are most often spoken in private, or muttered well below a level audible to others.

Not to criticize, but "dangitydarnheck" is suitable for the fabrication of teddy bears or flower arrangements. Aircraft and racing vehicles require powerful expletives, as the juju is strong. Here are a few tips for effective deployment of suitable words and phrases.

Unless raised in a convent, you're already familiar with the most popular four letter words. The secret lies in matching these key words with colorful pronouns and adjectives. For example, the phrases "You dumb.." or "I'm such a stupid.." can predicate a wide variety of four letter favorites, and are particularly appropriate in the case of miss-drilled holes.

Advanced applications include preliminary phrases. For example, a loud exclamation describing female canine parentage may proceed one of the previously given pronoun examples.

Like most skills, effective builder profanity requires practice. Lock the shop doors, chuck a #30, drill a hole in your finger, and be creative!
Love it, I'm still trying to tame the language skills I learned from 25 yrs in the airline, some folks just don't understand how important it is to use word skills when working on stuff, they actually find it offensive for some reason
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