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  1. #1

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    This Takes Danger To A New Level

    I just saw this on another site.

    http://www.hobbyking.com/hobbyking/s...247&aff=421628

    I love the comment one guy made " be the first one to set your local flying field on fire with one of these". While the idea of a ram pulse jet is intreaguing it is also incredibly dangerous since it can't be trottled or shut down once it is started. Since this type of engine is more like a rocket than a jet they also acellerate to amazing speed. I can see flying something like this in the desert where there is no one to run into and nothing to burn but I can't imagine flying something like this with more than 45 seconds worth of fuel in it.

    Someone is going to get hurt.
    RC Aircraft/ Three Laws Safe.

  2. #2
    ...
    Last edited by Hokie Flyer; 10-25-2013 at 08:04 PM.

  3. #3
    Kmot's Avatar
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    There are several fellows in Europe who have been flying pulse jet powered RC planes for years. Search Youtube for the videos. Nothing dangerous about them as long as you use common sense.
    ~Tom~

  4. #4

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    Quote Originally Posted by Kmot View Post
    There are several fellows in Europe who have been flying pulse jet powered RC planes for years. Search Youtube for the videos. Nothing dangerous about them as long as you use common sense.
    Unfortunately not everyone in our hobby is endowed with common sense. Also, the people you speak of machined their own parts and built the ramjet engines themselves so they have a very good understanding of what they were dealing with, what to expect, and how to safely employ it. Being available to any idiot just makes this an accident waiting to happen. I can see someone running a 16 ounce gas tank going down in flames over someones home. Any guess as to what that would do?

    There needs to be some sort of regulation for a device like this.
    Last edited by topspin; 10-25-2013 at 11:07 AM.
    RC Aircraft/ Three Laws Safe.

  5. #5

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    Hi Gents ,

    I saw that as well , and to be honest with you my first thought was of how I would fit one to one of my planes for a bit of fun .

    My second thought mirrors that of Toppers and Rob , that is cheap enough to price it within easy reach of the "Hold my Beer and watch THIS !!" crew . Even the cheapest turbine jet , the "Jet Joe" will cost someone 1K to obtain , and so turbine models have been for those with pockets deep enough to cover the potential damages of their toy .

    This brings me to my third thought , and yes , that is one of damages . Now , as we all know , the only model airplane specific insurance that most folks have is the AMA . The AMA requires a "Turbine Waiver" (permission to fly an RC jet after being checked out by an AMA appointee) to provide insurance coverage to RC jet operations . I have never seen in print where the pulse jet fits into the insurance picture , but I can't imagine them as being considered anything but jets , since they darned well don't fit the description of piston (Reciprocating) engines .. My best educated guess , and that's all it is , is a GUESS , is that without a Turbine Waiver any accidents would not be covered by the AMA . I know this don't mean a lot to the average "Hold my Beer and watch THIS !!!" guy , but those of us who have the good sense to cover their financial responsibilities ought to be seeking an answer to just HOW does the pulse jet get insurance coverage BEFORE giving in to their "Rocketman" urges ...

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    Meh...you used to be able to buy pulse jets from the back of Popular Science Magazine waaaaayyy back when from Edmunds Scientific (??) if I remember correctly.

    any chance to bash HK is OK though and expected for the OP

    ghostofpf1

  7. #7

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    I remember seeing a video some years ago of a German modeler, George Vogelsang I believe. He had a model of an ME 163 comet with a pulse jet engine, was a pretty cool setup.

  8. #8

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    "I don't approve... so, you shouldn't have them."

    Same old story.

  9. #9
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    Last edited by Hokie Flyer; 10-25-2013 at 08:02 PM.

  10. #10

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    There are real problems with such an engine. For one thing they are incredibly loud and most flying fields have noise restrictions. They are also more like a rocket in priciple than a jet although they are naturally aspirated instead of carrying an oxydizer. The point being that they are live flame engines, even more so than a turbine, and the exhaust will ignite anything around it including the contents of the fuel tank if it crashes. They develop a good deal of thrust to weight so they can propel an airplane very fast (really, really fast), and if not properly built for the load the airframe will come unglued.

    Then there is the Hey, hold my beer and watch this $#&t crowd who will bolt this on to anything and fly it. While it is a cool concept I still think that only someone with the proper G2 and set of skills should be allowed to fly one.

    Oh and for ghostofpf1 aka imgumby aka Steve, who did I bash and how? You might want to provide some details cause I'm a little fuzzy on that part.
    Last edited by topspin; 10-25-2013 at 12:59 PM.
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  11. #11

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    Quote Originally Posted by ghostofpf1 View Post
    Meh...you used to be able to buy pulse jets from the back of Popular Science Magazine waaaaayyy back when from Edmunds Scientific (??) if I remember correctly.

    any chance to bash HK is OK though and expected for the OP

    ghostofpf1
    I must have missed where in the original post that HK was bashed ? It sure looked to me that Topspin commented on the product itself , and made no derogatory remarks tword the vendor ? Maybe YOU shouldn't go accusing folks of things that the rest of us can clearly see are false ?

    now , if ya wanna bash HK , OK , Here's one for ya

    Gee , leave it to HK to bring us the "Lawn Darts" of the 2000s

    Happy Now ?????

    Now , It appears to me that the OP was looking for a discussion as to the merits/dangers of this particular powerplant , with no regards to who the merchant is , is that correct Toppers ?
    Last edited by init4fun; 10-25-2013 at 01:21 PM. Reason: Changed my mind , Gumby will have to fight the HK thing out amoungst himself .....

  12. #12
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    Years ago, these were for sale in Model Aviation Magazine. That was before the nanny state minions began infecting the country.
    ME: \"I need a good rate down to one three thousand\". EXPRESS: \"Roger, we\'\'re coming down like a Bonanza full of doctors\".

  13. #13

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    Quote Originally Posted by init4fun View Post
    I must have missed where in the original post that HK was bashed ? It sure looked to me that Topspin commented on the product itself , and made no derogatory remarks tword the vendor ? Maybe YOU shouldn't go accusing folks of things that the rest of us can clearly see are false ?

    now , if ya wanna bash HK , OK , Here's one for ya


    Gee , leave it to HK to bring us the "Lawn Darts" of the 2000s

    Happy Now ?????

    Now , It appears to me that the OP was looking for a discussion as to the merits/dangers of this particular powerplant , with no regards to who the merchant is , is that correct Toppers ?
    Yeah that pretty much sums it up. If i want to bash HK you know I don't have any problem in that department but this is about a power plant that has dangerous potential, more than IC, Electric, or even turbines if it is misused or used in a shoddy airframe. You have to realize that this motor is all or nothing, ther is no throttle so it's WFO all of the time until it runs out of gas. There is a you tube video of Bruice Simpson (who else), you should be buds with him Steve since you work together, anyway it shows him flying it for just a few seconds. Imagine if it was fueled up for five minutes.....

    http://www.youtube.com/watch?v=tgp3j-odseo

    Notice the hearing protection. Also, the only way that I know of to shut it down is to run it out of fuel. Someone may have a servo controled valve but I have not seen one.
    Last edited by topspin; 10-25-2013 at 01:51 PM.
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  14. #14
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    When I was in Huntsville AL years ago .. one of the German Nasa engineers - a really old guy from wwII era who moved over to work for NASA- had a pulse jet german model... it was really cool and LOUD!! didnt fly like a trainer but managable. Anyway, he had a plate activated by a servo on channel 5 that would block off the inlet to shut it down if needed. It would run like a bat out of he11 for about a minute with a dead stick landing. The whole thing would be entertaining with him hollering someting in German from start to landing. Neat guy. anyway that's my only exposure to the pulse jet.
    Bill B
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  15. #15
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    LOL.. Guys this has been around for longer than MOST of the people on RCU...... We are talking from the early 1940's...... LOL ROFL... This just cracks me up...hahaha...

  16. #16
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    whoa!

    I survived How did that happen? Lets see it was 1959 and I was fourteen years old. On one of my dads weekly trips into Hollywood to buy film stocks at the Eastman distributor he dropped me off at Reginald Dennys hobby shop over on Hollywood Blvd to make a purchase, something I had saved for quite a while.

    That purchase was a shinny new OS, Yes OS type 11 pulse jet. It took a while also to locate a model T coil with the vibrator for the shower of sparks ignition system and it used a 6 volt latern battey to run the coil. Of course a bicycle pump was also required. first test runs were made static and were shut off after around five seconds to avoid overheat. and yes the externally mounted engine requires airspeed for cooling.

    I finally got to fly it on a modified Darpa short pan and the rest carved wood. I used a two line system. It was wonderful and pretty fast but nothing like even a modern RC pylon ship these days.

    First, they are not ram jets and they are not rockets. I never destroyed anyones hearing including my own (they are loud but not nearly as much as folklore would have you believe. I never burned down anyone or anything! I survived, how did that happen and I was just a fourteen year old kid?

    Also note that they of course can be shut down with a simple pinch off device operated by a servo or bellcrank. So sure they should be regulated ya think, OK so by whom? and where are the regulations supposed to stop, Oh I get it right up to the point where it gets to whatever kinds of airplanes that are flown by those screaming for more regulations!

    Oh yes I also still have my treasured OS after all these years, The engine that flew great and never hurt anyone or burned down anything.

    John
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  17. #17
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    +1


    Quote Originally Posted by JohnBuckner View Post
    whoa!

    I survived How did that happen? Lets see it was 1959 and I was fourteen years old. On one of my dads weekly trips into Hollywood to buy film stocks at the Eastman distributor he dropped me off at Reginald Dennys hobby shop over on Hollywood Blvd to make a purchase, something I had saved for quite a while.

    That purchase was a shinny new OS, Yes OS type 11 pulse jet. It took a while also to locate a model T coil with the vibrator for the shower of sparks ignition system and it used a 6 volt latern battey to run the coil. Of course a bicycle pump was also required. first test runs were made static and were shut off after around five seconds to avoid overheat. and yes the externally mounted engine requires airspeed for cooling.

    I finally got to fly it on a modified Darpa short pan and the rest carved wood. I used a two line system. It was wonderful and pretty fast but nothing like even a modern RC pylon ship these days.

    First, they are not ram jets and they are not rockets. I never destroyed anyones hearing including my own (they are loud but not nearly as much as folklore would have you believe. I never burned down anyone or anything! I survived, how did that happen and I was just a fourteen year old kid?

    Also note that they of course can be shut down with a simple pinch off device operated by a servo or bellcrank. So sure they should be regulated ya think, OK so by whom? and where are the regulations supposed to stop, Oh I get it right up to the point where it gets to whatever kinds of airplanes that are flown by those screaming for more regulations!

    Oh yes I also still have my treasured OS after all these years, The engine that flew great and never hurt anyone or burned down anything.

    John

  18. #18
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    I'm opposed to (fill in the blank) being readily available to irresponsible people.
    After 5PM slip brains through slot in door.

  19. #19

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    I concur my pulsejet experience with John B. and purchased/flew my first pulsejet engine as a teenager. It was an OS Tiger jet, which was a Japanese copy of the US made Dynajet-first manufactured in the late 1940's. The engine was initially mounted and run on a test stand clamped to a parkbench in NYC. I later built a controline model called the Reso-Rambler and competed in controline Jet Speed, AMA Event # 309. This model was also flown at several flying fields in NYC including Pelham Bay and Willets Point. Not having automobile access I transported everything to fly the model on the NY subways-(would not do that today). Other than the noise and heat it was no big thing.
    Note that the AMA has two Documents covering the Declaration and Safety Regulations for pulsejet engines powered RC models- see AMA Docs # 510Q and 510R, available on the AMA website: www.modelaircraft.org. Following these regs, AMA insurance covers RC pulsejet operation on RC models. I've witnessed several RC pilots flying pulsejet powered models with no problems or concerns or than heat and noise. While not throttable they can be shut down as quickly as any other RC model.
    The HK appears to be a clone of the US-made Dynajet and I may consider purchasing one-for old times sake.

    Art ARRO

  20. #20

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    I can see how they would be much safer in a control line scenario. Looks like 99 percent of the old timers were just that and that's fine, they can't really get away from you. I wonder why they fell by the wayside, hmmm? Gee could it be that they get hot enough to light a smoke off of after 30 seconds? Could it be they will burst into flames when they crash (don't deny it)? Could it be they are loud enough to wake the dead? could it be all of the above?

    Our hobby has enough bad press from recent events with the lame brained FPV / Quad crowd and I for one would likr to be able to continue flying. All I'm saying is that some idiot will get their hands on one of these and we will get yet more bad press because of some stupid action.

    And please spare me the OT stuff. I'm no kid, probably older than you. I used cathode keyed rigs running 800 watts as kid in " the good old days" and I'm also still here but it could just as easily have been a disaster and there were some. This is one technology that needs to continue it's path to obscurity.
    RC Aircraft/ Three Laws Safe.

  21. #21

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    Quote Originally Posted by topspin View Post
    I just saw this on another site.

    http://www.hobbyking.com/hobbyking/s...247&aff=421628

    I love the comment one guy made " be the first one to set your local flying field on fire with one of these". While the idea of a ram pulse jet is intreaguing it is also incredibly dangerous since it can't be trottled or shut down once it is started. Since this type of engine is more like a rocket than a jet they also acellerate to amazing speed. I can see flying something like this in the desert where there is no one to run into and nothing to burn but I can't imagine flying something like this with more than 45 seconds worth of fuel in it.

    Someone is going to get hurt.
    One small correction. Easy to stop and they quite often stop on their own as the fuel must be fed at a constant pressure. One tiny air bubble and they instantly stop and as I recall, loss of pressure also can instantly stop them. I have seen them flame out a number of times at the old US model aircraft Nationals, in the Jet C/L Speed event.

    The CL models used centrifugal force to force the fuel to the motor, but thankfully, that does not work on R/C and you will need a pressure regulated fuel system. I think some R/C models used some sort of bladder tank, but I think there used to be a pressure system available as well.
    Last edited by Thomas B; 10-25-2013 at 03:46 PM.
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  22. #22

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    topspin,
    Pulsejets probably fell by the wayside due to easier, less complex methods of model propulsion, ie glow engines, electrics, etc.
    I agree that some "idiot" will purchase a model pulsejet which "may" result in some stupid action. However, I see this almost everytime I'm at the flying field-by 3D helis/gassers or lately, quadcopters. You can't legislate or regulate stupidity.
    The AMA has considered pulsejets for RC applications and has developed and approved regulations for their safe operation-see the previously referenced Documents #510Q and 510R.
    I don't see where 800 W cathode keyed rings enters the discussion but maybe they should be binned for posterity.

    Art ARRO, AMA #2070/ Leader Member/ Contest Director/ Fixed wing Turbine Waiver # 2570.

  23. #23

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    Thomas B,
    Further correction-model pulsejets do NOT reguire a regulated pressurized fuel system to feed the motor. They use a very conventional venturi, same as a standard model RC glow engine, to draw fuel from the tank. Granted, that the suction is more critical to fuel level/tank height but they operate just fine without a pressurized/regulated fuel system.
    I can't believe all the misinformation posted on this thread!

    Art ARRO

  24. #24

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    The engine does appear to be a clone of the old Dynajet. My job as a teenager was to run the manual tire pump to move air into the engine to mix with the fuel and ultimately ignite. At that time you could get blisters from pumping that tire pump before the "WHOOMP!" came out of the tail pipe. As control line power plants they were spectacular when you finally got one started and turned it loose!

  25. #25

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    a suggestion here. could someone with experience and knows what they are talking about do a write up on the safety and how to's of running these things and try to get it so when someone types in "rc pulse jet engine" or similair there is a resource to atleast give them an idea on some sort of safety. i looked and couldnt find anything. if i could id possibly buy one of these depending on the setup procedures and that. just right now i dont have any information as to what desicion i could make. im sure that other people out there have gone and made the desicion to buy one, probably with no idea what they are doing, and will jet burnt for it, literally


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