Talk:Walter HWK 109-509

Spellcheck
Wasn't the builder's name Hellmuth Walther? And shouldn't the spelling be changed? Trekphiler 17:03, 13 August 2007 (UTC)


 * For the record, apparently not. See Hellmuth Walter. - BilCat (talk) 06:37, 25 September 2017 (UTC)
 * Thx for the reply... (I've seen it rendered Walther, so presumably somebody got it wrong.)  TREKphiler  any time you're ready, Uhura  22:57, 27 September 2017 (UTC)

On kp
While I'm sure it's meaningful to Europeans, converting kp to kN isn't remotely informative to those who still think in terms of pounds of thrust, so can somebody convert...? TREKphiler  hit me ♠  04:25, 30 August 2008 (UTC)

Not a rocket? (!)
The way I read this, this engine used an outside source of mass as propellent in addition to the fuel and oxidizer. That makes it not a rocket. Or, at least not a pure rocket.

Ambient air was introduced into the exit flow by fluid induction. This is akin to a turboprop, turbofan, etc. where much of the high kinetic energy of the low mass flow of a jet is used to accelerate a larger mass (of ambient air) by a smaller delta-V -- which results in a larger thrust for smaller fuel consumption.

It was a smart design for (probably) better cooling as well as for better fuel efficiency, but it's dubious to call it a "rocket". At a minimum, qualifying words explaining how it's not a "pure" rocket should be added. I'm not adding it right now because I don't have a source, but it's a problem that should be considered.

96.237.114.137 (talk) 20:41, 14 March 2016 (UTC)


 * A rocket with a thrust augmenter like this is still a rocket. It would be good to improve the description of it though, especially if there are some sourceable numbers to go with it. Andy Dingley (talk) 20:48, 14 March 2016 (UTC)
 * Also an article for that redlink would be nice. Andy Dingley (talk) 20:51, 14 March 2016 (UTC)

I'm thinking that being able to operate without the air induction might be a reasonable way to make the distinction. Anyway, my take on what gets called a "rocket" would be that all of it's propellent comes from within the vehicle. An augmented rocket would be called an "augmented rocket", IMHO. I'm not pushing hard, just bringing it up. It's a fine point in a gray area where reasonable knowledgeable people can get away with calling it whatever is convenient for the purpose. If we can find a source mentioning that it's "augmented", then it would be worth adding a mention I think.

96.237.114.137 (talk) 21:09, 14 March 2016 (UTC)


 * What's "propellant"? Provided that the "reaction mass" is brought along in the tankage and it's not an air-breathing engine in the reaction sense, then I'd see it as a rocket.  Thrust augmenters like this don't add any momentum, they just change the "impedance" between mass flow and velocity to improve overall coupling. Andy Dingley (talk) 21:33, 14 March 2016 (UTC)

I've used "propellent" to mean any and all "reaction mass". In a turboprop, the reaction mass is mostly the air accelerated backward by the propeller while some of the reaction mass is the exhaust from (fuel + combustion air). So for a turboprop, reaction mass (or "propellent") is mostly from the environment (the propeller air plus combustion air) and only somewhat from within the vehicle (the fuel). Similar for a turbo fan except substitute "fan" for "propeller". It's also similar for a turbojet except substitute "bypass air" (if any) for "fan" or "propeller" air.

In the case of this motor, there's "induced intake air" which is added to the fuel and oxidizer, all of which is "reaction mass" (or "propellant" as I've called it). It's similar to a turbofan or a turbojet-with-bypass except there's no "combustion air" component because the oxidizer comes from onboard.

If by "impedance", you mean accelerating more mass by a smaller delta-V (which is more energy efficient) instead of less mass by a larger delta-V for the same thrust (which is less energy efficient), then "yes" it's better "impedance matching".

My main point is that for something to be accurately called "rocket", all of its reaction mass must come from onboard. Otherwise, it's an "augmented rocket" or even a "jet". :-)

96.237.114.137 (talk) 22:39, 14 March 2016 (UTC)

I notice now that the linked "propellent" article is focused on chemical fuels and doesn't mention other kinds of rocketry where materials other than the energy source might be used and called "propellent" (ion drives, nuclear rockets, etc). However, the article is very badly sourced and is dubious in it's chemical focus. I shouldn't have linked to it. 96.237.114.137 (talk) 22:55, 14 March 2016 (UTC)
 * Sorry, I mis-worded that (too tired). Rather than reaction mass I meant propellant mass - ie that which is reacted (chemically) rather than the mass with a Newtonian reaction force. Andy Dingley (talk) 23:02, 14 March 2016 (UTC)

Requested move 9 March 2019

 * The following is a closed discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. Editors desiring to contest the closing decision should consider a move review after discussing it on the closer's talk page. No further edits should be made to this section. 

The result of the move request was: Moved: request to revert undiscussed move from a couple of years ago, no prejudice against speedy RM if previous mover disagrees. (closed by non-admin page mover)  SITH   (talk)   14:08, 16 March 2019 (UTC)

Walter HWK 509 → Walter HWK 109-509 – The editor that changed this did not understand that the 109- is pivotal in RLM designations, as it indicates that this is a reaction engine (jet / rocket / pulse jet) and not anything else, such as 8-109 which was the Bf 109; see : List of RLM aircraft designations Petebutt (talk) 07:26, 9 March 2019 (UTC)


 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page or in a move review. No further edits should be made to this section.