ZDZ 40 RE, 60 plus oz of fuel now

[Jim_Woodward at beaerospace.com]

Thanks Brett and Vince,

I've had a number of off-line emails from folks expressing their interest 
in a gas engine.  Heres my take on it what I'll get to find out through 
experimentation.  What does a 4C glow have over a 2C glow?  It is 
basically noted as having better downline breaking, no pipe issues, more 
consistent throttle settings for a given throttle stick position wether 
you are acceleratingor decellerating the engine.  What does the electric 
setup have over a glow setup?  The most significant difference on the 
geared setups is the ability to swing a 20+" prop.  Of course there are 
other factors which I'm not going to get into, but to me, the most 
significant difference is the large diameter prop and the overall speed 
profile/presentation you get with it. 

What does the ZDZ gas engine give us?  computer chip controlled timing, 
larger prop blade profiles than the electrics, comprable vibration to the 
glow setups, 2-cycle simplicity, no need to tune a pipe, seems to be close 
to the battery/weight tradeoffs for the electric setups in terms of the 
heavier gas engine.  Concerned about cost of glow fuel? 

My main goal is to determine (since I have very little gas experience) if 
the chip-controlled auto-advance timing combined with the huge prop blade 
profile offers a throttle control and flight profile advantage to flying 
FAI.  Thus far, the larger the prop I put on the Webra 160 and the slower 
I can fly the FAI pattern, the easier it is to do consistently. 

Regarding the noise, I've been running in the opening of my garage so it 
seems loud as hell at full throttle.  I've waled a few meters away and at 
idle, the windmilling of the prop and mechanical sounds of the motor are 
more prevelant than the popping of combustion. 

Thanks and keep passing on the experience.
Jim





brett terry <brett.terry at gmail.com>
Sent by: discussion-request at nsrca.org
11/30/2004 12:55 PM
Please respond to brett terry

 
        To:     discussion at nsrca.org
        cc: 
        Subject:        Re: ZDZ 40 RE, 60 plus oz of fuel now


Dick Hanson taught me how to run these engines.  They really start to
wake up after two or three gallons.  I used the Bambula and MAS
Scimitar 20x10 prop on it, so yours must really scream.  The 13# IMAC
plane had far-beyond-unlimited vertical penetration but could not
really cruise at "pattern speed".  Perhaps the APC 18x14 2-blade would
work in pattern.

One other note:  the pump in the carb only works at low throttle.  If
you try to choke it at WOT the fuel draw depends only upon the suction
from the engine.  My starting procedure is like this - after fueling
flip the prop two or three times, close the choke turn on the ignition
and set the throttle to high idle plus a couple of clicks, flip it
until it pops (3-8 flips), open choke, flip it once and it runs.  The
idle is super-slow and full throttle doesn't really sag on uplines. 
This is the sign it is broken-in.

After you get a few gallons through it switch to Redline 2-stroke
racing oil at about 50:1 and enjoy!  The best part is the cleanup
after flying.  They are almost as clean as electric planes, no more
30% fuel, and no more DZ broken cranks.  The con rod has roller
bearings at both ends, and your local lawnmower shop carries parts to
fix the carb.

I have enjoyed your updates on this engine.  There are a few new 2M
planes designed around these gas engines and I am axcited to see what
they can do.

Thanks!

Brett


On Mon, 29 Nov 2004 17:55:44 -0500, Bill Glaze <billglaze at triad.rr.com> 
wrote:
> Jim:
> Next time, could you be a little more detailed about what you're 
doing?<BG>
> Great job of giving us an idea of what's happening on the engine.
> A couple of years ago, Dick Hanson was doing a lot of work with the ZDZ 
40
> Side Exhaust.  He had a lot of figures on performance, etc. that would
> possibly be relevant to the work you're doing now.  He was very 
enthusiastic
> about the engine.  Gerry Dale also did a lot of work on putting a gasser 
in
> a pattern plane of his own design; you possibly saw the article in RCM a
> couple of years ago; the airplane was called "L'Essence" (not sure about 
the
> French spelling) but I've seen him fly it in Masters and it did all the
> maneuvers.  It was marginal as far as weight went, and was sitting right 
at
> 11 lbs, Gerry said.
> 
> Bill Glaze
> 
>
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