Talk:Pintle injector

Image needed

I am willing to do a CAD draft of the pintle injector in order to make sure there are no copyright issues. If anybody else is trying to upload an image, please wait a few days first. Thank you. (this text dated November 23, 2015) — Preceding unsigned comment added by 181.10.86.74 (talk) 01:48, 24 November 2015 (UTC)

Added image as promised. — Preceding unsigned comment added by Marianoberna (talk • contribs) 16:48, 25 November 2015 (UTC)

I have updated the pintle injector image to make it more clear. I hope I have attributed the new image correctly. Any problems with attribution, let me know please. RedTomato (talk) 10:55, 11 October 2017 (UTC)

Suggestions for improvements

This is definitely a solid start. Having read the citations, which present excellent summaries of the concept, I recommend the following to get this up to B-class and beyond:

• More in the header -- let the reader know what makes the pintle distinct from other engines in the header

• More history and more cons. The Soviets used the pintle, too, but they aren't listed. Also, I know what the pintle does, but not why it hasn't become a prevailing rocket design.

• A more complete table of users. Just the articles cited list many more than what's there.

My two cents! --Neopeius (talk) 18:12, 18 February 2019 (UTC)

---

I've been working on this. I've improved the header, added more references, and added more engines. It seems that unearthed some engine models not covered in Wikipedia already, so there's potential for new articles there. I've also added images of the propellant flow in pintle injectors.

I'll keep you posted and I'll ask for recategorization when I feel the article is at B or better. Marianoberna (talk) 11:42, 25 February 2019 (UTC)

TODO's

• Find sources for Soviet aspects of Pintle engines
• add a diagram to show the dual circulation zones and maybe also illustrate film cooling.

Marianoberna (talk) 21:10, 25 February 2019 (UTC)

Prose revisions

Hello! I rearranged the header and cleaned up the language:

• "A pintle injector is a type of propellant injector for a bipropellant, liquid fueled rocket engine. Like any other injector, its purpose is to ensure appropriate flow rate and intermixing of the propellants as they are forcibly injected under high pressure into the combustion chamber, so that an efficient and controlled combustion process can happen.[1]"

Like any other injector... X Y and Z... should be followed by "But what makes the Pintle Injector different is A, B, and C" You've got what makes pintles unique after the patent info. It should go before.

• "The origins of the pintle injector were early laboratory experimental apparatus"

changed for improved grammar

• "A pintle injector can also be set up in such a way as to automatically provide fuel film cooling to the combustion chamber walls, without incurring the mass penalty of a dedicated film cooling subsystem. [2]"

This line is too abstruse for the header. I've removed it. You'll want to make sure it's in the body somewhere.

• "It was first used on a crewed spacecraft during the Apollo Program in the Lunar Excursion Module's Descent Propulsion System,[2][3] however, it was not until October 1972 that U.S. Patent 3,699,772 for inventing the pintle injector was granted to Gerard W. Elverum Jr, of TRW and made public.[2]"

"Pintle injectors are currently used in SpaceX's Merlin engine family.[4]"

Make these the end of the header.

• Thank you for all your work on this article! It's going to be a good one. :) --Neopeius (talk) 04:02, 4 March 2019 (UTC)

I'll work on those points and get back to you. Thanks for your time. Marianoberna (talk) 23:16, 4 March 2019 (UTC)

Further improvement

In the Advantages and Disadvantages section, it needs to be more clear which is which and why. Instead of a series of sentences, arrange your points into paragraphs starting with the key advantages followed by less significant advantages followed by the key disadvantages and then less important disadvantages. You mention heat concentration being an issue, but not what the result of that heat concentration would be(localized burn-through?)

--Neopeius (talk) 23:06, 4 March 2019 (UTC)

I'll rework that. With respect to heat concentration, I included throat erosion if using ablative cooling, but someone else removed it and stated that an Elon Musk tweet was not a valid source (!) Maybe it can be re-included somehow?

Marianoberna (talk) 23:16, 4 March 2019 (UTC)

Disadvantage: Erosion, removed due to source problems

User:Kees08 removed this paragraph, arguing that an Elon Musk tweet is not a peer-reviewed, reliable source.

"As the mixing is not completely symmetrical, pintle-based engines tend to have hot and cold streaks across the flow. In ablatively cooled engines, this can create zones of increased erosion rate. "

I disagree with that assesment, based on a few facts:

• Mr. Musk is an engineer, and lead designer of Spacex. (Elon_Musk)
• He has worked along with Tom Mueller in the design, and qualification of the Merlin 1A, and Kestrel, which are pintle engines that are ablatively cooled. (Merlin_(rocket_engine_family)#Merlin_1A)

I'd rather not restore the paragraph before getting a bit of discussion to form a consensus.

Let's get this conversation started!

Marianoberna (talk) 23:37, 4 March 2019 (UTC)

Part of my rationale is that Musk's pintle injectors may cause hot streaks, but that may not be indicative of hot streaks in general. If it is a common phenomenon across all pintle injectors, it should be easy enough to find in peer-reviewed research. I will take a preliminary look in some resources that I have. For what it is worth, I have worked with pintle injectors too, and my tweets would not be considered a RS either. Kees08 (Talk) 23:49, 4 March 2019 (UTC)

Musk's pintle injectors may cause hot streaks <- This is a good point I hadn't thought about. If anything else, it could be readded with a caveat to the tone of "E. stated that the early Merlin's had ablation problems at the throat due to, yadda yadda yadda.", thus clarifying that a) it doesn't necessarily apply to all pintle engines, and b)it's a statement from a person knowledgeable in the matter, not a definitive authority.

I await any source you can find among your material! Also, this is slightly off-topic, but, if you happen to have any source about Soviet use of the pintle I'd greatly appreciate it. It seems the Soviets used it, but I can't find sources to include that fact in the article. Marianoberna (talk) 23:59, 4 March 2019 (UTC)

I am pinging various colleagues about this issue and will let you know what I find out. The responses have been pretty mixed so far. Kees08 (Talk) 08:47, 6 March 2019 (UTC)

References

Images

@Marianoberna: I saw the images that you uploaded come from a book (I lost the link to it, but saw them in there). Unless you took the photos, and the organization you did the work under gave you permission to release them under the license they are claimed, they will have to be deleted out of the article. I can, as a consolation prize, take a pintle injector that I have access to and run a couple of water flows to produce similar images. The design is slightly different so the effect will not be as exaggerated. It will be a bit until I have enough time to do so (a couple weeks at least). Let me know if I understand teh situation correctly on the copyright of the photos in the article; I can help you get them deleted if necessary. Kees08 (Talk) 08:53, 6 March 2019 (UTC)

Let's get them deleted just to be on the safe side, and I'll try to:

a) contact the author for permission, and, b) get in touch with a friend of a friend that has done some work on pintles, to see if he has any images he could license us.

However high resolution, color images would still be better than the current low-resolution black and white ones, so, I'd appreciate it if you could take pictures anyways. — Preceding unsigned comment added by Marianoberna (talk • contribs) 11:58, 6 March 2019 (UTC)

I've obtained high resolution, color images of a pintle being tested at Purdue University's Maurice J. Zucrow Laboratories, and also I have obtained permission from the author to upload to wikipedia. — Preceding unsigned comment added by Marianoberna (talk • contribs) 04:00, 10 March 2019 (UTC)

Commons files used on this page have been nominated for deletion

The following Wikimedia Commons files used on this page have been nominated for deletion:

• Both flows.png (discussion)
• Inner flow only.png (discussion)
• Outer flow.png (discussion)

Participate in the deletion discussions at the nomination pages linked above. —Community Tech bot (talk) 06:06, 7 March 2019 (UTC)