New Guy Question about HS Spar Channel

[Wilkie]

Hi Gang,

I just received my Empennage kit yesterday and already I have a question.

Today I was going to trim the flanges on the HS-702 Spar Channels so that I could make the 6 degree bend but I'm just not understanding the instructions. I've been looking at the drawing and re-reading the manual for the last hour and I think I have an idea of what I'm supposed to do but I'm not sure of a couple of things.

First, the construction manual states that a #30 relief hole is to be made "centered on the bend radius of the flange". If I'm understanding that correctly, I would not hold the drill bit perpendicular to the spar web, nor would I hold the bit perpendicular to the spar flange. Instead, I should hold the bit at a 45deg angle. Is that right?

Next, the manual states that "it is not critical that the edge of the tab of HS-702 extends to the very vertex of HS-710 and HS-714. I guess I should not have thrown away my geometry book after high school but what the heck is a vertex?

Any guidance or pictures would be greatly appreciated!

Thanks........
Scott

 

[jcoloccia]

Hi Gang,

I just received my Empennage kit yesterday and already I have a question.

Today I was going to trim the flanges on the HS-702 Spar Channels so that I could make the 6 degree bend but I'm just not understanding the instructions. I've been looking at the drawing and re-reading the manual for the last hour and I think I have an idea of what I'm supposed to do but I'm not sure of a couple of things.

First, the construction manual states that a #30 relief hole is to be made "centered on the bend radius of the flange". If I'm understanding that correctly, I would not hold the drill bit perpendicular to the spar web, nor would I hold the bit perpendicular to the spar flange. Instead, I should hold the bit at a 45deg angle. Is that right?

Next, the manual states that "it is not critical that the edge of the tab of HS-702 extends to the very vertex of HS-710 and HS-714. I guess I should not have thrown away my geometry book after high school but what the heck is a vertex?

Any guidance or pictures would be greatly appreciated!

Thanks........
Scott

re: the hole in the flange
Yeah, just drill it @ 45 degrees. The hole's not super critical. It's just relief for the bend you're gonna make. It'll probably look nasty by the time you're done with the unibit anyhow...you'll probably end up cleaning it up with some emery cloth or a file anyhow

re: the tab/vertex thingy
Leave the tab a little long. When you're done drilling the skin, you'll see that the tab extends beyond the skin a little bit. Mark the excess with a sharpie and trim it off when you take it apart to debur/dimple etc.

If you look really closely at the first picture, you'll see the tab sticking out beyond the skin.

http://www.ballofshame.com/flying/rv-7/buildLog/20051123.php

 

[Jamie Aust]

Hi Wilkie,

The best help I have found for myself is to look at other websites that have some pics of what they are doing. IE Dan C web page is VERY good. Google is your friend !

I drilled mine at 90deg as I had not bent this part yet, thats what the hole is for, bend releaf.

Take your time, measure twice, cut once !

jamie

 

[RV7Factory]

Don't know if this will help, but here goes... Before on the left, After on the right.

More pics on this page.

 

[mototopo]

Hi all,
I'm at the same point of the construction and I have some doubt:

I alreay trimmed the flange as per instructions and made the #30 hole then enlarged to 1/4".

Now I'm ready to file the tab to smooth the corners left by the 1/4" hole, but what I don't understand is how to manage the residual flange where it has been trimmed. There is still a little bent and I don't understand if I have to cut it away or I have to flatten it in some way. In the picture posted by RV7factory, the edge of the tab looks like it goes straight to the flange. In my case, to have a perfectly flat tab I have to remove much more material and the edge of the tab, in that point, will not result parallel but will go inside (I don't know if I explained well my problem, english is not my first language, sorry!) The manual say to don't worry if the edge of the tab doesn't align perfectly with the HS-710 / HS-714, just take care of the distance between the edge and the rivet hole. I'm a little confused!!

Help please! (pictures will be veeeery helpfull)

 

[RadioShack]

I was a bit confused by this too. This is certainly an area Van's could use a little better instruction on. Don't worry it won't be the last. There are a few of these weird tasks.

I'm attaching a few pics of what I did. I looked ahead in the plans and sorta winged it. When I cut the excess material I had part of the radius (the part of the spar at the bend line) too. I just ground it down with a Dremel. It did cause the tab to be a bit narrower at that point. I bent the reinforcement angles and used them as a guide too, to make sure I would have enough material to rivet them to. Once you cut the forward spars, rivet them to the angles and put the HS together, you won't even where you trimmed this spot. I would just make sure you only take off what you need and finish the edges well so you don't have any issues with cracking down the road.

This is the picture where I made the initial cut and started to grind the remaining material left from the bend in the spar.

Here is a shot after I bent the spar tabs to the correct angle and did a trial fit to the reinforcement angles. I hadn't finished cleaning up the relief holes yet but it should give you and idea.

BTW, the craftsmanship in the RVFactory pic is unreal. I only wish I had those skills. Wow!!!

 

[mototopo]

Thank you Erik. I'll go on grinding down the excess material.
I'm curious to know how Brad obtained that great result.

 

[RadioShack]

Lots of Experience, Patience and Skill

I'm sure through lots of experience, patience and a lot of skill. It just comes natural for some people. I can usually produce decent results in the end but it takes some work. I just know I'm not great at the smaller work so I cut a piece long and slowly work (Grind, Sand, etc.) down to the line. It's amazing what a scotch brite pad, a small file and some fine sand paper can do.

One note though is that some people are perfectionists and just will not accept anything but perfection. This is a noble trait and makes for a rewarding build but we all have to decide which end of the scale we are on and stick to it. Personally, I am a perfectionist (I'm in aircraft maintenance in a test squadron for F/A-18's and various other types of fixed wing aircraft and helicopters - no margin for error, got keep the swiss cheese from lining up) at work but I know that if I apply those principles in my build, I will never finish this project. It's easy to become a victim of Scope Creep and want to do too much. If I drill a hole or pound a rivet and it isn't perfect I will make a quick safety of flight call and move on. I'll pound an ugly rivet from time to time and more often than not, drill it out and put in another one but on occasion, I'll let the embarrassing smiley face go...It's the price of working with metal. I think there might be a poll here.

Anyway, Good Luck...

 

[tyconnell]

Thanks for the pictures folks. Looks like I'm on the right track as well.