Conference vmszoo::rc

    BOY! Do I remember the Jetex, solid-fuel rocket motors?!  They provided
    me with more frustration than just about any other item in my early
    modeling days (except, perhaps, for the OK Cub .049 diesel I had).
    
    Installed in profile-type gliders, not unlike the 10-25 cent gliders
    by A.J. Aircraft (Jim Walker's American Junior models) except for
    the metal clip which accepted the Jetex-50 motor, about the best
    we ever got, on a _good_ day, was a powered glide.
    
    We had _mucho_ problems getting the fuel-pellet to ignite and, half
    the time, the fine wire core in the fuse would clog the tiny jet-
    orifice, producing a thrustless fizzle that did nothing but waste
    another pellet and fuse.
    
    Of course, we were just kids at the time and might do better with
    these fussy little devils nowadays but, unless they've been grossly
    improved in the operation and performance departments, I can't imagine
    WHY someone'd reintroduce them today, except for the nostalgia. 
    
    Oddly enough, as negative as my experiences with Jetex models sound,
    I still remember them warmly as a part of my early modeling developement.   

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    What a topic to bring back memories!  I was into Jetex way back
    when, in fact I built a very fast tethered car powered by Jetex
    from plans in one of the hobby magazines of the day.
    
    My favorite model however was of the X-20 Dyna Soar which appeared
    in American Modeller in the mid 1960's, I may still have the mag
    in my parents attic, I'll look this weekend when I visit them. 
    Great stuff, keep us posted on what you find.  Good luck!
    
    Scott
    

< Note 618.1 by CLOSUS::TAVARES "John -- Stay low, keep moving" >
< The August issue of Model Aviation has a ME16133B Komet for C02
< that could be converted...

I used to use the Jetex fuse for firing my models of Civil War canons. Great 
stuff, as long as you don't kink it.

Speaking of the Komet, (at least I think it was the Komet) what on earth was 
that little prop on the nose for? I also remember a friend telling some sort of
story about the Komet being so fast (how fast was it?) that the pilot didn't 
have time to react against a target in combat. He said that what they did was to
outfit the plane with light sensors and then, when they flew under the shadow of
an enemy target, the sensor would fire some sort of weapon straight UP. Any 
truth to this tale? What are the details?

Dave

    Dave,
    
    Since these answers are off the top of my head, they may still be
    debatable but I "think" they're acurate:  
    
    1. The "little prop on the nose" was to drive a generator to provide
    electrical power to the instrumentation, electrical systems, etc. The
    liquid-fueled rocket engine had no provision to provide such power.
    
    2, The ME-163 Komet was plenty fast by WW-II standards but not _that_
    fast, even by Korean war standards.  I believe the speed was in
    the mid-to-upper 500 mph range.  It was most definitely sub-sonic;
    Chuck Yeager broke that barrier in the Bell X-1 in 1947 with a speed
    of 670 mph at 42,000', just a tad over mach-1. 
    
    3. The vertical-firing gun system your friend refers to was never
    used on the Komet, which was much too small to carry this large
    a unit.  I can't call to mind the German name for this system but,
    literally translated, it meant "Jazz-Music."  The weapon consisted
    of one or more large caliber cannon mounted vertically behind the
    cockpit area, usually of an ME-110 or Me-210/410.  These could be
    fired manually or could be triggered by light sensors, as your friend
    suggested.  The theory was to fly beneath a bomber formation,
    supposedly its most vulnerable area, select a target, fly under
    it and unleash the cannon battery into the target's belly.  As I
    recall, the system was only moderately successful. 
    
    The Komet was lightly armed (I think it carried a maximum of two
    small [30mm] cannon with minimal ammunition) and had a very limited
    powered-duration.  Therefore, it barely had time enough to climb
    above a bomber-formation and make _1_ diving firing pass through
    the formation at upwards of 600 mph, then glide back to a landing.
    
    Obviously, this/these limitation(s) severely limited the Komet's
    effectiveness as an interceptor and, while impressive in theory,
    it never constituted much of a threat during the late stages of
    the war when it was used.  Approximately 300 Komets were built but
    these accounted for [as I recall] less than 10 enemy aircraft 
    destroyed and 2-probables.
    
    Just another desperate, last-ditch but futile attempt to turn or at least 
    slow the overwhelming tide of the war which was engulfing/destroying 
    Hitler's dream of a thousand-year-Reich.

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    
    Al, just another item on the Komet, I remember reading, I think
    in one of Wm Green's book's on fighters that the plane's fuel system
    was very leaky and the combination of the two leaking into the cockpit 
    lead to dissolved pilots....
    

    Yeah, and they frequently blew up for the same reason; fuel was
    hydrogen-peroxide and water.    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    I also have some Jetex experience dating form about '74-'75. The biggest
    problem that I had was that the wick would burn out at the nozzle opening.
    I actually got a couple of flights out of a converted rubber powered
    model but I had so much trouble starting the engine that I shelved the
    project. The wick worked GREAT for model rockets though!!!

                     !
                   --+--
G. Schrader     o___<0>___o
                  *  *  *

    Hydrogen peroxide was not the fuel- it was the oxidizer.  The fuel was
    ethyl alcohol and water. 
                                             
    I thought the powered flight duration was 8 minutes.  2 minutes
    at 300MPH straight up wouldn't get them to 30,000 feet, and
    the ME262 had _no_ trouble reaching the highest-flying bombers
    we had.  Admittedly it had only a short time available once there
    (2-4 passes typical).
                           
    Typical armament was a cluster of fin-stabilized rockets in the
    nose.          
    
    Takeoffs were from a zero-length runway (launch ramp); landings
    were on a belly skid.
                                             
    Typical mission profile was to wait until the bomber formation was nearly
    overhead, launch, attack coming up, cut engine, dive, attack going
    down, attempt engine restart, attack once again going up, cut engine,
    head down (attack again if any rockets left), burn (or dump) any
    remaining propellant; dead-stick it onto the field.  Total duration
    30 minutes of flight, 8 minutes powered.
                             
    	(or so I recall...)

Bill,

OK, you've forced me to dig out my reference material on the Komet and double-
check my statements.  Looks like we're both right, at least partially.

>    Hydrogen peroxide was not the fuel- it was the oxidizer.  The fuel was
>    ethyl alcohol and water. 

*  OK, I'll concede to that; the oxydizer, hydrogen-peroxide and water, was 
known as T-Stoff.  The actual fuel, known as C-Stoff was hydrazine-hydrate, 
methyl-alcohol and water.  Maximum static thrust from the Walter 109-509A-2
rocket motor was 3300 lb.'s, producing a maximum speed of 600 mph.
                                             
>    I thought the powered flight duration was 8 minutes.  2 minutes
>    at 300MPH straight up wouldn't get them to 30,000 feet, and
>    the ME262 had _no_ trouble reaching the highest-flying bombers
>    we had.  Admittedly it had only a short time available once there
>    (2-4 passes typical).

*  I think you mean the ME-163 here, not the "ME262."  In any event, I can find 
no data on duration and I certainly don't contest yer' claim that the Komet had 
little difficulty reaching our bomber formations.  My memory seems to like the 
figure 3-to-5 minutes duration but I can't support that supposition.  Where'd
the "2 minutes" come from?  I never said anything about 2-minutes.
                           
>    Typical armament was a cluster of fin-stabilized rockets in the
>    nose.          

* My source says, and I quote:  "The swept wing, tailless ME-163 was armed with 
two 30mm MK-108 cannon; some machines are known to have carried experimental 
armament systems."  Perhaps one of these experimental systems was the rockets 
you refer to but standard armament was the two small cannon, per my source.
    
>    Takeoffs were from a zero-length runway (launch ramp); landings
>    were on a belly skid.

*  True.  Jettisonable, 2-wheel dollies were sometimes used as well.
                                             
>    Typical mission profile was to wait until the bomber formation was nearly
>    overhead, launch, attack coming up, cut engine, dive, attack going
>    down, attempt engine restart, attack once again going up, cut engine,
>    head down (attack again if any rockets left), burn (or dump) any
>    remaining propellant; dead-stick it onto the field.  Total duration
>    30 minutes of flight, 8 minutes powered.

*  Can't argue with this as, I have no duration or mission profile data to sup-
port or deny it.  Sounds reasonable enough _IF_ air-restarts were a practical 
possibility.  BTW, did you know that a famous aviatrix (whose name escapes me)
flew many of the test-flights of the ME-163??  Regardless of gender, that
gal had "big brass ones!"  ;B^}
                             
Well, now that we've managed to burn up several potential trivia questions and
de-rail this topic, maybe we should back out, gracefully (if that's possible),
with our thanks for not bashing us for the digression.  :B^)  :B^)  Let's put 
any subsequent conversation on the subject somewhere else, (though I'm not sure
where) OK?

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

>>Note 618.10                  Jetex nostalga returns                     10 of 12
>>CTHULU::YERAZUNIS "Smurf _Terminator_"               23 lines  21-JUL-1988 17:00
>>                  -< What an ugly little bugger it was, too! >-
>>    ...  2 minutes
>>    at 300MPH straight up wouldn't get them to 30,000 feet...
>>


I'm staying out of the argument, but...

300 MPH is 5 miles per minute. In 2 minutes, you'd do 10 miles or 
52,800 feet, so ...

ajai

    ...my calculator can't add either...
    
    You're right.  They're at 25000 feet in just 56 seconds.  So 2 minutes
    of powered flight actually gives them quite a bit of time on-target.
    
    -----
    
    After all of this work, ya gotta build one!  

    Just reading at lunch and noticed on page 58 of the August 1988
    issue of "Flying Models" some Jetex stuff you all might be interested
    in.
    
    There is a Jetex newsletter called "Psssst-Off Sheet" for $8.00
    available from Roger Wathen Sr., 3242 No. DeQuincy, Indianapolis,
    IN, 46218.
    
    Also in that "flying Models" issue are pictures of two Jetex models
     a F-94C Starfire and a Douglas Skyray both from old Jetex kits.
    
    Scott

        re: film @11 
        
        Cardboard? Tell me more.

        re: .15
        
        I've known Roger for a couple years. He and his son have showed up
        at a few of our model rocket contests. I've got some issues of
        Psssst-Off, but his publication schedule is quite irregular. 
        
        re: whatever
        
        A Jetex HLG is exactly what I'm looking to do. All the plans I've
        seen so far for Jetex models look about as much like a HLG as an
        armadillo does! The boost dynamics would be quite different from
        an HLG or one of my rockets. 
        
        One of the other "projects" on a back burner is to static test one
        of these beasts, and find out what they really do. Another AMA
        member has tried to petition the AMA to declare some model rocket
        motor the "equivalent" of a jetex, as allowed by the AMA rules,
        but it hasn't happened yet. From rough data I've seen so far, my
        guess is it might be something like the A10-3T or A3-4T. The
        models would be quite different, encountering higher stress, and
        launching vertically.