Bearhawk Patrol Scratch builder

[Nikkeyf]

Hello all. I am actually a member of a forum for about a half year already and I am building my patrol in Torrance California for about the same time. I'm still working on my wings. So far all ribs were formed and at the moment im working on my spars. I don't want this project to be a slow builder so I dedicate a lot of time in that. I heard a lot about unfinished projects too, so to keep me excited about the end result I have Zenith ch300. It is not the same thing as Bearhawk, but at least I still remember how to fly I'm excited to be here and will be happy share my experience building the airplane!

[rodsmith]

That is great progress and a nice looking Zenith!

[BravoGolf]

Nice progress. Welcome to the club.

[N3UW]

You look like you are making great progress. Well done so far. Keep up posted with your progress. Love to see the photos. Please ask lots of questions. Many of us have already made the mistakes we hope to help you not make.

[Chewie]

Welcome aboard, and yes ask lots of questions. At your rate of progress I'll soon be the one asking you the questions.

[Nikkeyf]

Thank you guys!

[Nikkeyf]

In my recent post we were discussing if it is possible to fix the wrong hole on main spars that I made. With some paper "plate emulator" I have managed to cut the plate of a right size and shape. As you can see on the plate, there is a spot where 3/16 hole supposed to be according to the drawing right next to my modification that worked just fine. Not proud of my mistake but happy that I was able to fix it. Keep building!

[sjt]

During my build I have had to slowly adapt. When I started I would try to get things accurate to a thousandths. That did not last long. The next thing I did was try to get everything as lite as possible. I now realize that was a waist of time.

For example, the angles that attach to the spar probably are called out as something like 1/2x1/2. That is what you would do if you wanted it as lite as possible. That is not what you would do if you were trying to finish in a reasonable amount of time.

I think I recall N3UW saying make them 9/16x9/16. I should have listened to him. If you want to go faster make the flanges bigger then 1/2x1/2 . The smaller flanges are a pain to drill without violating rivet edge distances. And even latter you will have to grind down squeezer dies to fit in such close quarters.

I have to use mental tricks. You know like when the dentist is hiding the novacain shot behind there back when they are approaching you. Pretend you do not know whats up.

In a similar way I make them 9/16x9/16 now and tell my self that after all of the drilling and making sure that the holes are not near the edge - that I can go back and file the edge down a little.
I know that I will never go back and do that but it helps me move forward.

[Nikkeyf]

Thanks Stan! Good timing as I will start working on angles soon!

[svyolo]

During my build I have had to slowly adapt. When I started I would try to get things accurate to a thousandths. That did not last long. The next thing I did was try to get everything as lite as possible. I now realize that was a waist of time.

For example, the angles that attach to the spar probably are called out as something like 1/2x1/2. That is what you would do if you wanted it as lite as possible. That is not what you would do if you were trying to finish in a reasonable amount of time.

I think I recall N3UW saying make them 9/16x9/16. I should have listened to him. If you want to go faster make the flanges bigger then 1/2x1/2 . The smaller flanges are a pain to drill without violating rivet edge distances. And even latter you will have to grind down squeezer dies to fit in such close quarters.

I have to use mental tricks. You know like when the dentist is hiding the novacain shot behind there back when they are approaching you. Pretend you do not know whats up.

In a similar way I make them 9/16x9/16 now and tell my self that after all of the drilling and making sure that the holes are not near the edge - that I can go back and file the edge down a little.
I know that I will never go back and do that but it helps me move forward.

I have always thought of myself as weight conscious when building things. But building an airplane, finally, I have learned a huge amount. Minimum edge distance, is also maximum edge distance. Any more material, and it is just dead weight. The extra material is adding nothing structurally, just extra weight.

[Nikkeyf]

Made another mistake. Talked to few people- they have advised me to talk to someone more experienced than I am before scraping the whole thing. What do you guys think? Any way to save this?

[Sir Newton]

That is fixable, Maybe build a new end connection plate. If you want it to look pretty. I maybe out of place here being new & all. But I would slap a 1/8 fish plate over the entire assembly on the damaged side & call it GOOD! Rivets are always in shear never tension. Just my 2 cents.

[N3UW]

Made another mistake. Talked to few people- they have advised me to talk to someone more experienced than I am before scraping the whole thing. What do you guys think? Any way to save this?

I agree with Sir Newton. That should be fixable. Possibly a new attach bracket and possibly longer to catch another rivet. I would just give Bob a call and get his recommendation on the best fix.

[Sir Newton]

100% Bob will know best. You just can not replace the kind of experience Bob has.

[sjt]

There is great value in discussing mistakes. I think something like that happened to Chewie and he had to remake attach plates.

I stopped trying to make everything as lite as possible and made sure to learn from previous builders problems.

Here is how I made that part.

On amazon I found long metric screws that are smaller then a 40 drill size. I used screws to hold together a sandwich of plates so that I could use my router with a bearing.


one.jpg


two.jpg(1)The first plate is 1/4 lexan made undersize.
The plate has the underside counter sunk so that screw heads do not touch router table and lexan plate can slide.


(2)NOT SHOWN IS THE 1/8 2024 BLANK WHICH IS THE NEXT PLATE IN THE SANDWICH
(2)NOT SHOWN IS THE 1/8 2024 BLANK WHICH IS THE NEXT PLATE IN THE SANDWICH
(2)NOT SHOWN IS THE 1/8 2024 BLANK WHICH IS THE NEXT PLATE IN THE SANDWICH



three.jpg(3)this is a 1/16 lexan undersize spacer .
I need the router bearing to only touch the above metal master template.
All other lexan has to be smaller


image_11168.jpg
(4) This is my template plate.
It is made out of 1/16 aluminum door kick plate I got from Home depot.
I used a scribe to mark every detail.
I did not make it as small as possible.
You can see the lines on the plate that show where the capstrips will be under them.
I took no chances that there would be rivet edge distance problems.

I know it is not as lite as possible.


five.jpg(5) 1/4 lexan undersize cover hold down plate

[sjt]

In this picture you can see the front top capstrip.
I made the attach plate longer on the top.
I had to slowly sand it down so that the top capstrip would impinge on the attach plate.

I also must have made some mistake since I can see that I ended up putting in three AD6-14 rivets.
Maybe your luck with riveting is better, but when using large rivets it is imperative that the the shop end
be no longer then necessary, and it has to be made square.

capstrip.jpg


This is the most evil and useless tool I have.
It will not cannot make square rivets.
evil.jpg

Desert Bearhawk had a video where he sanded down the rivet with a steel plate.


I know this is stupid, but this is how I made square rivets You can not get half size rivets when you want them - unless you are Boeing.
You have to make them sometimes.
stupid.jpg

[sjt]

I am not sure if AD6 rivets can be done with a 4x gun. They certainly can not be done with a 3x.

I bought a tool from clevland:
clevland.jpg


And attached it to my C-frame
c-frame.jpg

I made various rivet sets. This is necessary because the 3/16 dies are not going to survive many uses of back riveting without breaking.
I drilled a hole thru the center so that I could remove broken bits.
I then hardened the rivet set.

You can see several broken dies.
Replacing a die is not so bad. Replacing the rivet set every time is annoying.
set.jpg

This is my setup when I used a 3X gun:
rivetgun.jpg

When using a hammer I had too use what blacksmiths call a monkey tool to protect the c-frame shaft:
hammer.jpg