What type of rivets are these?

[Mark Thompson]

These are on an Curtiss XP-10 frame. from 1930.

6931

[Bill Berson]

Probably long tubular (hollow) steel rivets that go clear through the tube and a shop head is formed on the other side.
A long solid aluminum rivet will tend to bend inside the tube, but can be used. See the AC 41.13 chapter on rivet splicing aluminum tubes.

[martymayes]

They look like somewhat conventional blind rivets.

[Mark Thompson]

ac 41.13 Chapter refers to MIL-HDBK-5. I dont have access to that hand book. not available on line with out paid subscription. I found every revision of MIL-HDBK-5 has been canceled.

this aircraft was built before handbook became standard.

[Bill Berson]

I was assuming that was aluminum tubing. It could be silver painted steel tubing.
I don't think those are pop rivets because pop rivets were likely invented later and I can't see a stem in the hole. And Pop rivets probably wouldn't be approved.
A tubular rivet is what you get if you drive the mandrel out and discard the mandrel, from any pop rivet. And then hand squeeze or hammer the tubular rivet.

[martymayes]

Blind rivets been around longer than that elephant trap.

[Mark Thompson]

​
I was assuming that was aluminum tubing. It could be silver painted steel tubing.
I don't think those are pop rivets because pop rivets were likely invented later and I can't see a stem in the hole. And Pop rivets probably wouldn't be approved.
A tubular rivet is what you get if you drive the mandrel out and discard the mandrel, from any pop rivet. And then hand squeeze or hammer the tubular rivet.

Bill the frame was made of DURALUMIN, equivalent to 2024 Aluminium

found this info online. looks good to use building frame and brackets.

Semi-tubular Rivets




https://www.rivetsonline.com/includes/work/image_cache/d919938c26fba57e9cf0eed13cd98313.thumb.png (https://www.rivetsonline.com/includes/work/image_cache/d919938c26fba57e9cf0eed13cd98313.thumb.png)





Click image to enlarge


Semi-tubular rivets (also known as tubular rivets) are essentially the same as solid rivets (https://www.rivetsonline.com/index.php?cPath=313_183), but with a shallow hole at the tip, opposite the head. This hole causes the tubular portion of the rivet (around the hole) to roll outward when force is applied. This reduces the amount of force needed for installation—tubular rivets require roughly ¼ the force of solid rivets.

[BoKu]

That Curtiss frame sure is a work of art!

I bet that if you sectioned one of the joints, you'd find that there is an internal sleeve around the rivet as shown in the attached sketch. The sleeve would prevent the tube from crushing completely flat under the force applied when setting the rivet. It also makes sure the rivet does not cripple or collapse, and provides clamping force for the set rivet.

6933

[Bill Berson]

Mark, I can't see if they are fully tubular (as post 9) or semi- tubular.
Even solid rivets can be used if a small hammer is used to peen the sides of the shop head instead of straight hits. The technique is described in AC 41.13 for aluminum tube splicing.

With a bushing (post 9) any long solid rivet will work. But inserting the bushing is difficult. I would insert a short solid rectangular bar in the partly flattened tube end. (I have thought about this quite a bit)

[Mark Thompson]

That Curtiss frame sure is a work of art!

I bet that if you sectioned one of the joints, you'd find that there is an internal sleeve around the rivet as shown in the attached sketch. The sleeve would prevent the tube from crushing completely flat under the force applied when setting the rivet. It also makes sure the rivet does not cripple or collapse, and provides clamping force for the set rivet.

6933



Doing some more investigation. I bought a book AIRCRAFT MAINTENANCE for the Airplane Mechanic. by Brimm and Boggess. 1940

H. Edward Boggess was Ground School Instructor; Flight Mechanic Curtiss Flying School.

The book is a guide to proper Aircraft maintenance procedures ..... Below is an explanation of a form of hollow rivets. Which didn't actually start out as rivets but are home made.

[CraigCantwell]

Mark: Here you go on MIL-HBDK-5 Rev J:
http://everyspec.com/MIL-HDBK/MIL-HDBK-0001-0099/MIL_HDBK_5J_139/

If you look up one listing above the J rev, there is the cancellation notice with the reference to the new book, Metallic Materials Properties Development and Standardization (MMPDS).

Everyspec.com is a great reference library and it's free.

[Mark Thompson]

Thank you Crag. Downloaded it.