The Aerodrome Home Page
Aces of WWI
Aircraft of WWI
Books and Film
The Aerodrome Forum
Help
Links to Other Sites
Medals and Decorations
Search The Aerodrome
Today in History


The Aerodrome Forum


Go Back   The Aerodrome Forum > WWI Aviation > Aircraft > Replica Aircraft

Replica Aircraft Topics related to the construction of WWI replica aircraft

Reply
 
Thread Tools Display Modes
Old 27 January 2024, 02:33 PM   #71
piecost
Two-seater Pilot
 
Join Date: Apr 2008
Posts: 117

 
Aeroplane Structures, Pipard & Pritchard, 1919

A sketch waffle tree rig for testing ribs from a textbook from 1919. I assume that this captures the British state of the art during the Great War.
Attached Images
File Type: jpg IMG_20240127_222956819_HDR.jpg (54.2 KB, 31 views)
piecost is offline   Reply With Quote
Old 27 January 2024, 03:26 PM   #72
MattS
Two-seater Pilot
 
Join Date: Sep 2022
Location: Wellington, New Zealand
Posts: 119

 
I would love copies of those pdfs, will PM you my email address.

On that diagram, there is some serious math required to get that system of levers and pulleys to work correctly. Will be very interested in the text that goes with it
MattS is offline   Reply With Quote
Old 28 January 2024, 01:58 AM   #73
Jeff Brooks
Forum Ace of Aces
 
Jeff Brooks's Avatar
 
Join Date: Dec 2004
Location: Rochester, NY
Posts: 3,311

 
Quote:
Originally Posted by piecost View Post
Comparison for load factor of various British Aeroplanes including the Camel
Here are easier to read pages from the April 1920 Aeronautical Journal that Piecost posted.


Last edited by Jeff Brooks; 28 January 2024 at 02:41 AM.
Jeff Brooks is offline   Reply With Quote
Old 30 January 2024, 12:14 AM   #74
MattS
Two-seater Pilot
 
Join Date: Sep 2022
Location: Wellington, New Zealand
Posts: 119

 
Quote:
Originally Posted by Jeff Brooks View Post
Here are easier to read pages from the April 1920 Aeronautical Journal that Piecost posted.
Thanks Jeff (& Piecost). Load factor of 7 it is :-) Interestingly that puts the kybosh on my thoughts the doubled flying wires were for combat redundancy.

That makes the rib test benchmark; 7 * 27 lb == 189 lb or 86kg

It's going to take a couple or three weeks to do the test and come back with results.

Meantime, big thanks for the help, input and research!
MattS is offline   Reply With Quote
Old 17 February 2024, 02:34 AM   #75
MattS
Two-seater Pilot
 
Join Date: Sep 2022
Location: Wellington, New Zealand
Posts: 119

 
Just a quick update. Tested my first of three ribs today, all made of rejected material as practice runs.

First one failed at 50kg. Specifically it failed next to the rear spar fracturing across the cap strip where it was penetrated by a screw. After spending a bit of time examining the results, I am left with four conclusions.

1. Better materials obviously, but that will happen in the next phase.
2. The glue used was effective for testing purposes (even if not suitable for the final aircraft). There was evidence of wood failing before the glue. However...
3. Glue at the break point was not present/not effective. This was to avoid getting glue on the spar itself, so was deliberate. Will change this approach.
4. The cap strips were not screwed into the spar per the plans. This was also deliberate. In hindsight the screws may have spread the load, possibly isolating the stress caused by ~10kg weight on one side and ~20kg on the other side of that spar. Alternatively the screw holes may introduce new weak points in the cap strip - further testing needed. Tied in with this is the question of whether the groove in the cap strip should exist over the spar.

Overall, I'm not convinced the substandard parts used in the test contributed to the fail. My working theory is that this failure was due to decisions made in the assembly process.

I have video of the test which includes talking through some assumptions and known flaws before the test. At the time I was also chatting with my mother (not expecting a fail at that point!!!) who had decided to join me - not sure yet how I will edit that out! Video will go up on Youtube late next week, possibly with test two if I get that set up and done over the week.

Breaking stuff makes a nice change from building stuff
MattS is offline   Reply With Quote
Old 19 February 2024, 12:59 AM   #76
MattS
Two-seater Pilot
 
Join Date: Sep 2022
Location: Wellington, New Zealand
Posts: 119

 
Second rib tested. ---- 91kg

Made changes to assembly as per first test. The rib survived 91kg (target 86kg) and did not break - it most definitely was not happy and is no longer useable - but it didn't break. I ran out of sand and couldn't go any further

91kg on rib test.jpeg

There were several, what I assumed would be critical, flaws in this rib, screws poking through the ply and two splits in the cap strip. The screws into the spar (top & bottom) appear to have played a major role in both distributing the weight and holding onto the lower cap strip (top cap in flight) when the centre web was being pushed down and out of position.

Adjustments for the next test include looking at how all that weight is hanging with a view to avoiding the rib bowing sideways (as it did in this test). Also need to consider how to add another say 30kg in a graceful way.

Overall pretty happy, this was the first and arguably the worst of the three test ribs. Looking forward to testing the third later in the week.
MattS is offline   Reply With Quote
Old 24 March 2024, 01:51 AM   #77
MattS
Two-seater Pilot
 
Join Date: Sep 2022
Location: Wellington, New Zealand
Posts: 119

 
Time for an update. It's been a busy month on other fronts so kinda just nudging things along when I can.

I decided to save my third test rib as on reflection I think I learned what I needed to which was mostly around improving my assembly skills. The next test will be of a production rib further down the track.

Tried gluing ribs. I get the process but didn't like that I couldn't see the underside of the rib to clean off excess glue. It was compounded somewhat by getting the T-88 I ordered and coating both surfaces to ensure a good bond (with larger than expected squeeze out in places). End result was gluing the rib to the jig. Yes - I know I could use wax paper but that implies accepting large globs of dried glue on one side.

So... currently screwing ribs together. After completing four it's definitely slower than gluing them in the jig and I have yet to actually glue them. But it means I can make multiple at a time as there is no need to wait for glue to dry. When I do glue the top cap strip, I will be able to also glue multiple at a time as the jig will only be used to ensure shape as I tighten the screws. Then the rib will be removed, excess glue seen to and the rib left to dry on a flat surface, possibly with a weighted board on top. I have options with regards gluing the bottom cap strip.

Note that Camel ribs were supplied to the repair shops screwed together. They were glued in place on the spar.

The next month will be spent cutting out more webs from ply and creating more mainplane ribs Its a process!
MattS is offline   Reply With Quote
Old 24 March 2024, 03:12 AM   #78
cvairwerks
Observer
 
Join Date: Jun 2012
Posts: 59

 
Matt: One trick that might be of help. Where you have glue joints on your rib jig, use a Forstner bit and bore out a hole that is just a little larger than the joint. Makes it easy to see the joint and a bit harder to glue the rib to the jig. You can also use a modified staple gun to glue and secure the gussets as soon as the rib is glued up in the jig.

An EAA article by Tony Bingelis, titled "Making Wood Ribs", from SportAv of Feb 1994, shows the basic hole at the joint idea.
cvairwerks is offline   Reply With Quote
Old 24 March 2024, 03:43 AM   #79
MattS
Two-seater Pilot
 
Join Date: Sep 2022
Location: Wellington, New Zealand
Posts: 119

 
Quote:
Originally Posted by cvairwerks View Post
Matt: One trick that might be of help. Where you have glue joints on your rib jig, use a Forstner bit and bore out a hole that is just a little larger than the joint. Makes it easy to see the joint and a bit harder to glue the rib to the jig. You can also use a modified staple gun to glue and secure the gussets as soon as the rib is glued up in the jig.
I have seen that, it's a good idea. I can't use it here though as the rib is glued along the length to secure the cap strip to each of three ply webs. It would need to be a very long hole!!!

You can see the ply webs here (photo from earlier). It'll help picture the problem in this case.
Rib webs Dec2023.jpg
MattS is offline   Reply With Quote
Old 3 April 2024, 02:07 PM   #80
MattS
Two-seater Pilot
 
Join Date: Sep 2022
Location: Wellington, New Zealand
Posts: 119

 
A quick question, I may have found an importer of 1025 sheet steel for my Camel. They have asked whether I want normalised or annealed 1025. Any thoughts?
MattS is offline   Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
My Sopwith F.1 Camel project Dogtail2 Replica Aircraft 734 21 October 2016 04:27 PM
milling aluminum with table saw? j ferguson Replica Aircraft 22 13 March 2012 01:21 PM
1/48 camel project update Mike West Models 3 28 May 2011 07:14 AM
1/48 2-Seat Sopwith Camel Project Brad Cancian Models 24 4 January 2010 09:24 AM
Camel Project Available William Replica Aircraft 0 23 April 2007 11:43 AM


As an Amazon Associate we earn from qualifying purchases.

All times are GMT -7. The time now is 06:30 PM.


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Feedback Buttons provided by Advanced Post Thanks / Like (Lite) - vBulletin Mods & Addons Copyright © 2024 DragonByte Technologies Ltd.
Copyright 1997 - 2023 The Aerodrome