red wood
03-05-2015, 07:27 AM
#3
Senior Member
Check this out - http://www.fpl.fs.fed.us/documnts/fp...chapter_05.pdf
There are other qualities besides just strength that help determine suitability for structure - i.e. glue ability, machinability, availability, and specific weight - to name a few. I am sure that after a thorough analysis of its qualities, you could use redwood to build; however, I suspect that others before have tried and rejected it in favor of more suitable products.
If you do decide to use redwood, we would be most interested in seeing your project. Let us know what issues you encounter and how you solved them. Sounds intriguing!
There are other qualities besides just strength that help determine suitability for structure - i.e. glue ability, machinability, availability, and specific weight - to name a few. I am sure that after a thorough analysis of its qualities, you could use redwood to build; however, I suspect that others before have tried and rejected it in favor of more suitable products.
If you do decide to use redwood, we would be most interested in seeing your project. Let us know what issues you encounter and how you solved them. Sounds intriguing!
Last edited by Lone Star Charles; 03-05-2015 at 07:31 AM.
03-05-2015, 08:51 AM
#4
My Feedback: (132)
Join Date: Feb 2002
Location: Mt. Pleasant,
PA
Posts: 206
Likes: 0
Received 0 Likes
on
0 Posts
In my humble opinion. Stringers not too bad. Spars absolutely not. This wood will on occasion, depends on where in the tree the wood came from, have compression failures. These will lead to failure of the spar. Wood will almost always fail in compression first. Hard to detect.
Finally, you will never find redwood in any structural part of a full size plane mainly for this reason.
Mark
Finally, you will never find redwood in any structural part of a full size plane mainly for this reason.
Mark
03-05-2015, 10:07 AM
#5
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
Posts: 12,425
Likes: 0
Received 22 Likes
on
19 Posts
The few times I've handled redwood I didn't find that it was all that strong. But then much depends on the growth ring spacing just like with spruce.
For stringers I prefer woods with good flexibility that can spring under pressure and bounce back without having taken a set. This is where I seem to recall that redwood is rather brittle and snaps fairly easily when bent very far. But again it's a lot of years ago and I may have been working with wood that had a low ring count per inch.
When I buy pine, hemlock or fir to use as a substitute for aircraft spruce I'm always looking for a close spacing of the growth rings. We're really looking at slow growth stuff for our needs and you want to see 16 or more growth rings per inch when looking at the end grain and measuring radially. If it's considerably lower than that then the suitability of the wood for our structural needs drops off quickly.
Things like wood density will be affected by the ring density as well but I feel that the ring density is more important. The harder winter rings seem to be the part that most affects the structural properties. So the more rings per inch the better.
For stringers I prefer woods with good flexibility that can spring under pressure and bounce back without having taken a set. This is where I seem to recall that redwood is rather brittle and snaps fairly easily when bent very far. But again it's a lot of years ago and I may have been working with wood that had a low ring count per inch.
When I buy pine, hemlock or fir to use as a substitute for aircraft spruce I'm always looking for a close spacing of the growth rings. We're really looking at slow growth stuff for our needs and you want to see 16 or more growth rings per inch when looking at the end grain and measuring radially. If it's considerably lower than that then the suitability of the wood for our structural needs drops off quickly.
Things like wood density will be affected by the ring density as well but I feel that the ring density is more important. The harder winter rings seem to be the part that most affects the structural properties. So the more rings per inch the better.
03-05-2015, 10:44 AM
#6
My Feedback: (132)
Join Date: Feb 2002
Location: Mt. Pleasant,
PA
Posts: 206
Likes: 0
Received 0 Likes
on
0 Posts
Check this out - http://www.fpl.fs.fed.us/documnts/fp...chapter_05.pdf
This is a good resource as listed by Lone Star Charles. See page 5-33.
Mark
This is a good resource as listed by Lone Star Charles. See page 5-33.
Mark
Last edited by Champ-RCU; 03-05-2015 at 11:09 AM.
03-06-2015, 08:55 AM
#7
Senior Member
FAA manual AC 43.13-1B is also a very good resource. http://www.faa.gov/documentLibrary/m...-1B_w-chg1.pdf
03-06-2015, 11:12 AM
#9
Senior Member
Some of the above comment restored some old memories of have some problems with getting a strong glue joint with redwood. There is often an oily type feel to fresh cut redwood, a constituent of the sap I guess, that need to be removed (acetone works fairly well) in order to get a good strong joint regardless of the type glue or epoxy.
03-06-2015, 08:40 PM
#10
My Feedback: (1)
Join Date: Jan 2002
Location: Crystal,
MN
Posts: 1,294
Likes: 0
Received 0 Likes
on
0 Posts
Balsa USA sold redwood strip for a time (a short time). I used some to build a small Jungmeister but never flew the thing so I cant say how it holds up to actual use (see my profile page for a pic...)
Dave
Dave
Last edited by fritzke; 03-08-2015 at 09:00 AM.
03-07-2015, 05:41 AM
#12
Redwood is/was a wood of choice for outdoor endurance because it had a lot of natural oils that resisted water decay and for the same reason, does not accept glue penetration as well as other choices. Its grain structure will also spit when subjected to bending. As for spars, straight grain is a priority and redwood complies well in that regard. And most spars in models will not be bent to any degree that would cause grain splitting and thin CA may penetrate adequately. It is getting kind of pricey and in my opinion, falls into the category of, if you've got it - use it but if needed acquired, there are better and cheaper choices.
