Oops! Cut my jettison pushrods short!

cjensen · Post by **cjensen** » Tue Mar 04, 2008 9:59 am

This is a silly mistake by not LOOKING at the plans close enough. I read the plans to get the dimensions for the pushrod length...easy enough right? Yup, but ya gotta pay attention to where the dimensions actually go stupid...

I couldn't figure out what in the world I had done wrong! My first thought was that I had assembled the pivot block and bell crank wrong, but I had the exact shortage on both sides. That wasn't it. Then a really silly thought entered my mind...Is my sub-panel not cut right? THAT was a stupid thought...CAD designed and cut...not likely.

So, I go to the plans, and it jumped right out at me...

The dimension given is a center-of-hole to center-of-hole dimension, NOT the entire pushrod length, PLUS a 1/4" at each end past the hole! DOH!!!

No big deal here, I just wanted to pass this on to other tip up builders who plan to put the jettison mechanism in.

I'm gonna run over to one of the steel supply stores today to get another 15" of 3/8 4130 tubing to make new ones. You may be able to tell in the first picture that I needed to remake the short one anyway...the slots are not level with each other, and cause the pin to be canted up about 20 degrees, which caused some minor binding. It worked, but not good enough...

weezbad · Post by **weezbad** » Tue Mar 04, 2008 11:49 am

yeah i hear ya chad. there are a couple of other places this happens as well
the seat backs often get mispositioned for the same reason...the plans are correct and need to be viewed carefully at times. maybe these pics will save you some grief...note distance is measured from the edge of the sheet and not from the hole centerline. many folks complain about this but they are simply wrong. even he who should not be named.

jim_geo · Post by **jim_geo** » Tue Mar 04, 2008 2:27 pm

Yeah I had a laugh of relief. While looking through Dan C's web site and there is a page where he was complaining that the seat backs were in the wrong position. Apparently “The plans where drawn wrong”. They hit the roll bar and he had to cut into the seat backs to make them fit. Next day at the shop I reinstalled my seat back and they cleared but not by much. Over a few months of checking his site I came to the conclusion that he made several mistakes, although minor, that could have been avoided by staying on task and reading the plans and construction manual till he understood what was being said. As an aside; I pretty much gave up using that site for reference. You're not alone Chad when I built up my aileron push rods I read the total finished length as the length of the tube. Didn't figure it out till I went to install them.

cjensen · Post by **cjensen** » Tue Mar 04, 2008 3:04 pm

Ugh. NO ONE in town has 4130 anything! I had to order it from Spruce. It was cheap...$4 shipped, but I had hoped to be able fix it today or tomorrow. Oh well, there's plenty of other things to do...

weezbad · Post by **weezbad** » Tue Mar 04, 2008 3:45 pm

cjensen wrote: Oh well, there's plenty of other things to do...

you got that right

you can spend the evening laying out the firewall penetration(had to throw in the p word for captn john

) holes ...except the one that goes through fuel pump double. less your going fi and BTW, next time get those slots lined up..

captain_john · Post by **captain_john** » Tue Mar 04, 2008 3:52 pm

mmmmm, penetrations!

I just love that word!

When I billed for coring large holes in concrete they were ALWAYS called PENETRATIONS! You can get WAY MORE money for a penetration than a hole!

Besides, the double entendres that can be construed are limitless!

CJ

weezbad · Post by **weezbad** » Tue Mar 04, 2008 3:56 pm

jim_geo wrote: As an aside; I pretty much gave up using that site for reference.

ditto

cjensen · Post by **cjensen** » Tue Mar 04, 2008 9:19 pm

weezbad wrote:...except the one that goes through fuel pump double. less your going fi and BTW, next time get those slots lined up..

I'll be carb'd...

And, yeah, those slots are terrible! That one was gonna be made again anyway...

cjensen · Post by **cjensen** » Thu Mar 06, 2008 10:52 am

Got one side fixed. I used the longer of the two that I cut short to remake the short one. Worked great, and it now "locks" over center as it should.

I have a 1' piece of 4130 3/8" tubing on order from Spruce to remake the long one.

weezbad · Post by **weezbad** » Thu Mar 06, 2008 1:16 pm

hey, thats what i did.

dons · Post by **dons** » Thu Mar 06, 2008 1:19 pm

That looks much better Chad

. I hope your order to make the other tube shows up in a reasonable time. I placed an order last week with Spruce for stuff that they claimed was in stock, and this week they say it would be the end of March before they have any to ship (hardware stuff). Oh well, there's a whole lot of other tasks that can be done, I just find it sometimes uncomfortable to leave a task 'almost done' and move on.

cjensen · Post by **cjensen** » Thu Mar 06, 2008 2:23 pm

dons wrote:That looks much better Chad . I hope your order to make the other tube shows up in a reasonable time. I placed an order last week with Spruce for stuff that they claimed was in stock, and this week they say it would be the end of March before they have any to ship (hardware stuff).

Yeah, I've had things from Spruce take FOREVER to get to me, and the stuff was in stock. I hope to see it this week, but I'm not counting on it.

dons wrote:I just find it sometimes uncomfortable to leave a task 'almost done' and move on.

I'm the EXACT same way. I find it very hard to move on, basically "skipping" around in the intructions is something I won't do. In this case, this is all canopy frame related, so I'm not frettin' this one too much. If it was something unrelated, I would just stop until I had the part.

It's just me (and sounds like you to!).

dons · Post by **dons** » Thu Mar 06, 2008 4:16 pm

cjensen wrote:
It's just me (and sounds like you to!).

You nailed that one, I really like finishing a task when I get close, been known to stay in the shop to 1am on a week night when I really should have gone to bed hours before, just because I was "almost done".

cjensen · Post by **cjensen** » Thu Mar 06, 2008 5:39 pm

So I'm NOT alone!!

weezbad · Post by **weezbad** » Thu Mar 06, 2008 7:22 pm

dons wrote:
cjensen wrote:
It's just me (and sounds like you to!).

You nailed that one, I really like finishing a task when I get close, been known to stay in the shop to 1am on a week night when I really should have gone to bed hours before, just because I was "almost done".

ya know, this is why some people finish and others don’t. We have a vision, an unrelenting desire to finish what we start. This is why sometimes I won’t start something when others will. I know that to do it the way I want it, it will take to long. To the untrained eye many people look like total wrecks but are quite in control. It is hard for me to understand that I need to slow down and sharpen my axe.

this same desire can be harmful as well.

JohnR · Post by **JohnR** » Thu Mar 06, 2008 9:31 pm

Does everyone put the canopy release in? Seems I've seen several people who did not put it in. I guess it would not do much good to have it if you didn't wear a chute. On the other hand does it allow you to remove the canopy for maintenance? I'm pretty uninformed on this area, help me out.

Bob Barrett · Post by **Bob Barrett** » Thu Mar 06, 2008 9:49 pm

Wicks Aircraft has a good stock of materil and on small orders will mail parcel post. You have to self insure and I have done that on orders of up to $200. If they send me stuff from their St. Louis operation parcel post,
I have gotten the order in three or four days. They handle almost everything you can get from Aircraft Spruce and the prices are the same and shipping is less and faster. I live in Sartell, MN so it is not real far away.

cjensen · Post by **cjensen** » Thu Mar 06, 2008 10:03 pm

JohnR wrote:Does everyone put the canopy release in? Seems I've seen several people who did not put it in. I guess it would not do much good to have it if you didn't wear a chute. On the other hand does it allow you to remove the canopy for maintenance? I'm pretty uninformed on this area, help me out.

I would guess it's probably close to 50/50. I think very few who do put it in, actually put it in with the intent of using it to get out of the airplane if needed. There are a few things that need to be done to make it work that way...one being that the top front skin has to be notched, and covered with fabric to allow the hinges to pull out.

You are absolutely right in that the only way this would be useful, is if you and/or your passenger wear 'chutes all the time. That ain't happenin'.

It does allow for easier canopy removal IF it ever did need to be removed. That's probably pretty remote, but it'll be nice if I ever have to. The struts are the only thing that have to be unbolted to get the canopy off.

The struts are another item that no one really knows what would happen if the canopy were to be released in flight. Would they rip out? Would they not allow the canopy to come off? No one knows.

Ease of maintenance seems to be the only real practical purpose of putting it in.

Brantel · Post by **Brantel** » Fri Mar 07, 2008 8:59 am

cjensen wrote:The struts are another item that no one really knows what would happen if the canopy were to be released in flight. Would they rip out? Would they not allow the canopy to come off? No one knows.

Yea and the thing will most likely beat you to death as it is flailing around while it is trying to detach itself.

I plan on doing it like Chad, just for easy removal and I will also not be putting the handle thru the panel.

weezbad · Post by **weezbad** » Fri Mar 07, 2008 12:30 pm

it is doubtful to me that the struts would let go. i would pop them off prior to jettisoning the canopy. but really how much time will you have left. i think if you somehow manged to get the canopy to open and the struts were still hooked on it would do just as brantel said.. i may, at some point remove them and go retro with a prop rod.

these are no more than car hood struts. except 10 times weaker. hoods blow open and they dont let go.

i am giving some thought to wearing a chute dont really know