Titanium eye bolts/U-bolts

[steveh.jae]

Does anyone use titanium fasteners (eye bolts, u-bolts, nuts, set screws, etc.) in their builds? The excellent strength:weight ratio is highly favorable although I am not sure if low temperatures at altitude would increase brittleness significantly. I see some items listed, but they are often bulk sales from India/China. Has anyone pursued this in the past? Thanks.

 

[lowga]

Since the part would be exposed to low temperatures at altitude for a very short time, thermal transmission won't have time to occur.

Having said that, I have zero experience with titanium eyebolts.

 

[steveh.jae]

That was my initial thinking but I was unsure. I don’t see any of the major distributors (Apogee, LOC, AeroTech, PML, etc.) offering them as an option. I would think these types of fasteners would be highly desirable given the weight reduction advantages. The cost is prohibitive for individuals, but large clubs/prefectures or commercial distributors could easily make this “a thing”. Titanium is a BIG “thing” in the aerospace industry because of it’s strength:weight ratio.

 

[dhbarr]

That was my initial thinking but I was unsure. I don’t see any of the major distributors (Apogee, LOC, AeroTech, PML, etc.) offering them as an option. I would think these types of fasteners would be highly desirable given the weight reduction advantages. The cost is prohibitive for individuals, but large clubs/prefectures or commercial distributors could easily make this “a thing”. Titanium is a BIG “thing” in the aerospace industry because of it’s strength:weight ratio.

If you've only got need for a bolt or two, it may or may not make $ens$ to cut that weight by half.

EDIT: I was curious, looks like you'd maybe spend about a dollar for every gram you'd shave.

 

[jderimig]

You can ever reduce weight further by eliminated the eyebolt and thread your harness through the slots in the bulkhead.

 

[rharshberger]

The very limited amount of metal in a hobby rocket, makes the use of expensive "exotics" like titanium mostly unnecessary unless there is a specific application or problem to be solved. Most HPR rockets entire metal parts can be measure in a few ounces (usually aluminum or steel). Titanium is also relatively expensive and not readily available in most localities (read as cannot be purchased locally).

 

[lowga]

Hate to disagree folks, but the "cool" factor alone makes me want to pursue this as well. Besides, it pales in comparison to some of the things I've seen rocketeers do.

Why did you climb Mount Everest? Because it was there!

Let's bulk order some forged titanium eyebolts!

 

[heada]

I remember looking at yield strength of all-thread for e-bays. Titanium had a yield strength about 50% less than mild steel, which was about the same as aluminum. If you went to grade 8 steel, it was 20% of the strength. You're trading a 50% weight reduction, where it may not be needed, for a 50% to 80% strength reduction.

It has cool factor but on items whose primary purpose is strength, I'm going with the stronger, cheaper and easily sourced material personally.

 

[lowga]

Aaron,

Now that's a better argument. Strength is the primary requirement, especially for eyebolts. Cool will have to wait for another day.

 

[Rocket86]

I use titanium bolts and hi-loks in all my builds. Strong, light, and not that expensive because they're small. And cool.

 

[rharshberger]

I use titanium bolts and hi-loks in all my builds. Strong, light, and not that expensive because they're small. And cool.

You do have some very nice builds John.

 

[steveh.jae]

I remember looking at yield strength of all-thread for e-bays. Titanium had a yield strength about 50% less than mild steel, which was about the same as aluminum. If you went to grade 8 steel, it was 20% of the strength. You're trading a 50% weight reduction, where it may not be needed, for a 50% to 80% strength reduction.

It has cool factor but on items whose primary purpose is strength, I'm going with the stronger, cheaper and easily sourced material personally.

Heada
It appears that you think there is only one “grade” of titanium. Not true. There are several that provide far superior “strength” than what you purported. See images. These are the grade “types” I was proposing.

 

[steveh.jae]

I use titanium bolts and hi-loks in all my builds. Strong, light, and not that expensive because they're small. And cool.

Rocket86, where do you purchase your hardware? Thanks!
Steve

 

[Rocket86]

I get small quantities on ebay or from Aircraft Spruce.

 

[Richard Dierking]

I've been using aluminum (6061) for well over 5 years. Even had an unintentional high velocity deployment (>400 mph) and the hardware held. I've used aluminum 3/16", 1/4", and 5/16" size for all thread, u-bolts, nuts, nylon nuts, wing nuts, washers. From McMaster-Carr, all with no problems. Also, fins and other stuff. So, if aluminum works, why use titanium?
Hum... low temps at high alt. I've heard that often, and only gone to 25'K or so. But, I've never seen an internal temp decrease in any bay more than a few degrees. Where's the data that shows low internal temps at high alt?
What we typically use for airframe insulates well, and if you are using at least dual deployment, your rocket will be descending fast enough that the ambient temp should not be a problem.

 

[AfterBurners]

You can ever reduce weight further by eliminated the eyebolt and thread your harness through the slots in the bulkhead.

And not build your rocket like a brick or tank.

 

[beeblebrox]

Use a loop of 1000# test Kevlar cord, or thicker for even bigger rockets. it is strong and very light. (It, or a screw bolt will rip out of whatever it is attached to before it will break.) I use it anywhere you would use a screw eye or eye bolt. Altimeter sleds are a different story...

 

[Richard Dierking]

Yes, must look at the potential failure points and the overall strength of the system. It's kind of amazing how light and strong you can make stuff. Every CATO or damaged rocket is a great opportunity to take it apart and look at what works and what doesn't. This is why I stopped using hobby-grade epoxy and switched to using aluminum rather than standard steel or stainless steel hardware. And, I use thinner aircraft plywood or microlite and fiberglass the surface. Or, try fiberglassing the inside and outside of a paper tube. It's much stronger than two layers on the outside.
It's a fun aspect of the hobby; you find out that how you are building is just as important as what you are using for material.
I have looked at Titanium hardware. But, yikes! It's so expensive. I would rather use aluminum and spend the money on a MARSA!

 

[Richard Dierking]

It occurred to me that I might have missed a major point you where asking about. I apologize. Using Titanium would be cool and the cool factor does count.
If you decide to obtain and use Titanium hardware, please let us know steveh.jae.
I suggest getting it from somewhere that can provide some kind of documentation, like a quality certificate.

 

[lowga]

I'd like to salute Richard Dierking for:

A.) Evaluating new information and being willing to reconsider his initial conclusions.
B.) Apologizing.

Both are rare in this age, and we need more of it. Especially in a hobby like rocketry where science (should) rule.

We can never forget the cool factor. It's a hobby after all. That's kind of the point. Well done, sir!

 

[pbahorich]

Titanium is cool, certainly. But it is typically only used for high temperature applications on airplanes, for several reasons such as cost and difficult machinability.
Aluminum strength/density ratio is close to titanium since aluminum is quite a bit less dense. 7075-T651 aluminum has a yield strength higher than 316 stainless steel but is almost 1/3rd the density.
But aerospace grade titanium (6-AL-4V for example) has almost triple the yield strength of 316 stainless, but less than half the density.
https://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MTP641https://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MQ316Ahttps://asm.matweb.com/search/SpecificMaterial.asp?bassnum=MA7075T6
Based on this thinking, I think I may switch to aluminum allthreads to cut a few ounces out of my rocket:
https://www.mcmaster.com/94435A515/There is potential for galvanic corrosion between the steel nuts and aluminum, but this should be reduced by Loctite.
Aluminum is not as durable which is why they don't use aluminum screws in airplanes. So I need to be careful not to tighten much (and inspect for corrosion).

 

[mikec]

Counterfeit titanium is a big problem in professional aerospace even with all of the certification paperwork, so the chances of anything you could buy from cheap overseas sources being real doesn't seem great to me. As others have said, if you really want to save weight, there are easier ways to do it.

 

[FMarvinS]

Hate to disagree folks, but the "cool" factor alone makes me want to pursue this as well. Besides, it pales in comparison to some of the things I've seen rocketeers do.

Why did you climb Mount Everest? Because it was there!

Let's bulk order some forged titanium eyebolts!

Aside from being “cool,” titanium has minimal affects on signal propagation/attenuation compared to steel and aluminum. So, I use titanium all threads in the nose cones that contain my gps units and rf trackers.
Fred, L2
ICBM, CamdenSC
KG4YGP

 

[steveh.jae]

Aside from being “cool,” titanium has minimal affects on signal propagation/attenuation compared to steel and aluminum. So, I use titanium all threads in the nose cones that contain my gps units and rf trackers.
Fred, L2
ICBM, CamdenSC
KG4YGP

Thanks Fred. This is great information. What grade/alloy do you use? Where do you get your hardware, is there a link?

 

[ksaves2]

You can ever reduce weight further by eliminated the eyebolt and thread your harness through the slots in the bulkhead.

Man John, That is so simple. Is it advisable to tie interior knots at both ends to abut against the interior side of the bulkheads? It would seem to me that would keep the interior harness from sliding back and forth. Tie end loops at both ends for external connections and good to go. What is a nice thing about this is if the internal, thru-wall harness is looking worn, one can just simply replace it! Great idea. Only caution would be to make sure the pass-through doesn’t jam up against the electronics when under tension. Would need an ebay that has the size to accomplish that or a strong harness material that has a small diameter. Easy enough to do a pull test though. Clay or putty would be fine to prevent ejection gases from getting into the ebay. I’ve used it for years without problems. Never had an apogee charge screw up the electronics due to gas leakage into the ebay when using clay or putty. Kurt Savegnago

 

[FMarvinS]

Hi Steve-I bought a 1/4-20 grade 2 titanium all thread from Amazon (see below) for use in "glueless nose cones" (seen in Crazy Jim threads) to support GPS units/transmitters. McMaster Carr also sells them (#96095A155) but more expensive than Amazon.
Fred

 

[steveh.jae]

Thanks Fred,

McMaster can certainly be trusted as being the genuine article, although grade 2 Ti is probably little better than 1610 Al. I am most interested in grade 5 U-bolts, eye-bolts, nuts and bolts. Thanks again for your help. Good flying!

Steve

 

[TonyL]

Hi Fred,
I can find no evidence that titanium has different radio frequency properties than metals in general. Do you have any supporting information?

br/

Tony

 

[FMarvinS]

The following reference will support the concept that titanium is more RF transparent (i.e. has a smaller effect on RF attenuation) than aluminum and several types of stainless steel. Comparative properties are enumerated in https://www.azom.com/article.aspx?ArticleID=1298. The electrical conductivity of titanium is only approximately 3% that of copper and close to 8% of that of aluminum. RF signal absorption is directly proportional to conductivity; thus, titanium would absorb RF much less than copper or aluminum. In addition, both RF absorption and reflection (each a component of lower RF transparency) is also associated with iron content of the material in question. So, magnetically dominant waves (in this case generated by RF) are absorbed/suppressed by ferrous metal such as steel or stainless steel. Stainless steel (e.g. grades 304, 316, 409, 430 etc.) contain up to 51% iron which significantly diminishes RF transparency. In essence, of the materials discussed, titanium has the least affect on RF attenuation.

Fred

 

[steveh.jae]

The following reference will support the concept that titanium is more RF transparent (i.e. has a smaller effect on RF attenuation) than aluminum and several types of stainless steel. Comparative properties are enumerated in https://www.azom.com/article.aspx?ArticleID=1298. The electrical conductivity of titanium is only approximately 3% that of copper and close to 8% of that of aluminum. RF signal absorption is directly proportional to conductivity; thus, titanium would absorb RF much less than copper or aluminum. In addition, both RF absorption and reflection (each a component of lower RF transparency) is also associated with iron content of the material in question. So, magnetically dominant waves (in this case generated by RF) are absorbed/suppressed by a less conductive ferrous metal such as steel or stainless steel. Stainless steel (e.g. grades 304, 316, 409, 430 etc.) contain up to 51% iron which significantly diminishes RF transparency. In ferrous containing metals, a lower conductivity is associated with increased RF absorption (and decreased RF transparency). In essence, of the materials discussed, titanium has the least affect on RF attenuation.

Fred

Don’t hold back Fred ... tell us how you REALLY feel! Thank you so very much for that excellent information. Does this also mean that reactance is also diminished? This information seems to imply that Ti use in the north end of our rockets becomes ever more appealing on multiple fronts. All thread component distributors have already been discussed (I.e., McMasters) and I have seen grade 2 Ti set screws online. I will contact McMasters to see if they have any suggestions on reputable eye-bolt and U-bolt sources. Thanks again Fred!