Re: 049 test stand dont's

Tim Wescott wrote:
> Jim Chandler wrote:
> 
>> Tim Wescott wrote:
>>
>>> MJKolodziej wrote:
>>>
>>>> "Tim Wescott" <tim@[EMAIL PROTECTED]
> wrote in message 
>>>> news:B6-dnQFFFODdNPjVnZ2dnUVZ_uudnZ2d@[EMAIL PROTECTED]
>>>>
>>>>> Got a Cox reed valve 049 engine going today, with a Davis head.
>>>>>
>>>>> For a motor stand I'm using a Tatone stand with a piece of 1/8" 
>>>>> angle iron on which the engine is bolted.
>>>>>
>>>>> Don't do this, unless you want some practical education in 
>>>>> resonances. At the 'bad frequency' (which was just a bit lower than 
>>>>> what the engine really wanted to do) I could see the cylinder 
>>>>> moving through a 1/4" long arc.
>>>>>
>>>>> Very disconcerting.
>>>>>
>>>>> But I could damp it out by hanging on to the engine, so I verified 
>>>>> that it runs (and smells) normally for a little Diesel conversion, 
>>>>> and I have the compression and mixture at a good setting to go on a 
>>>>> plane.
>>>>>
>>>>> Tomorrow I go flying.
>>>>>
>>>>> Sometime soon I go get some nice thick T-bar and make a new test 
>>>>> stand adapter for 049s!
>>>>>
>>>>> -- 
>>>>>
>>>>> Tim Wescott
>>>>> Wescott Design Services
>>>>> http://www.wescottdesign.com
>>>>>
>>>>> Do you need to implement control loops in software?
>>>>> "Applied Control Theory for Embedded Systems" gives you just what 
>>>>> it says.
>>>>> See details at http://www.wescottdesign.com/actfes/actfes.html
>>>>
>>>>
>>>>
>>>> Cool!
>>>> How did you start it? Power or fingers?  Fuel tank attached or apart?
>>>>
>>> It's got a Babe-Bee tank.  Unfortunately it's going onto a plane 
>>> that's got a Golden Bee right now, and will need a spacer to get the 
>>> prop out far enough to clear the cowl.  So, maybe I fly Sunday.
>>>
>>> Cox 049s without mods don't do well being started with an electric 
>>> starter.  It can be done, but the prop drive and crank case are both 
>>> aluminum, so they get chewed up pretty quick.  There were supposed to 
>>> be some marine engines that had bronze or brass prop drives which are 
>>> supposed to work better.
>>>
>>> I've been thinking of taking one of my chewed-up crank cases (guess 
>>> how they got that way!) and fitting a steel collar at the end of the 
>>> crank case to run against the prop drive; dunno if I'd go to the 
>>> trouble of turning out a brass prop drive.
>>>
>>> At any rate, this one starts with a generous prime and a few healthy 
>>> flips by hand.  I had been using a chicken stick, but did you know 
>>> that rubber turns to black gunk in the presence of diesel oil and 
>>> ether? Fingers don't...
>>>
>>> The big challenge was getting the needle and compression adjustments 
>>> sorted out the first time; now it should go without adjustment.  I 
>>> need a tach, but it's turning a 7-4 prop 'good and fast' -- it sounds 
>>> barely slower than a glo 049 with a 6-4 prop, so it should pull my 
>>> slightly oversized control line job around pretty well.
>>>
>>
>>
>> Good Gawd!  You mean someone actually still flies .049 Ukies?  I have 
>> done that since I was a kid.  It WAS fun though.
>>
> 
> It still is.  Cheap, too, as long as the bucket-o-engines holds out.
> 
> I haven't done it for a while, so I expect to get dizzy -- this is the 
> driver behind the small tank, and may also lead to some BB's or bits of 
> Teflon in said tank until my middle ears adjust.
> 


Or you could use the ballet dancer/ice skaters trick and keep your head 
in one spot for a quarter turn or so then snap it around to catch up 
with where everything is then do it all over again.  Gives the ears a 
chance to stay equalized because the fast head movement then stop is 
faster than the ears can be upset.

Jim