> > > I am 90% done with the airframe of my dragon
fly I
> >
> > am intending to
> >
> > > power it
> > > with a 13b. Any comments? Anyone seen a rotary
> >
> > powered dragonfly?
> >
> > > would make
> > > quite a buzzz.....
> > > --
> > > Thanks,
> > > Brent Hasty
> > >
> > > Isn't it a bit heavy Brent?
> > >
> > > Paul Lamar
--------------------------------------------------
vw engines are around 165 lb average see:
http://www.greatplainsas.com/specsfd.html
I initially began to think about repowering with a
rotary when on the list
someone sent out a link to an outfit making
alumininum side plates, this
makes it around just 50lbs heavier than a vw for
well over twice the hp, not
to mention reliability issues...
What are other means to put a 13b on a diet, if one
were willing to sacrifice
a little bit of horse power?
I do not think a rotary powered dragonfly is
insurmountable.
------------------------------------------------
> > I'd think so.. I just about bought a Dragonfly
> > project, but was
> > discouraged by the weight limit for an engine,
and
> > who wants to
> > fly behind a VW motor?.. If memory serves me
> > correct, a c-85 was
> > to much weight. A single rotor would fit, but
that
> > might mean a
> > bit of a wait until they get on the market..
> >
> > Jarrett
--------------------------------------------------------------
What are the dynamics of aircraft performance that
are affected by a engine
weight increase like I am discussing?
Consider the reduction of stall by modifying the
Aelerons with a flaperon
mechanism similar to the kitfox and avid?
---------------------------------------------------------------
> I owned and flew a Dragonfly for many years. The
13B
> is too heavy and powerful for that design.
-------------------------------------------
How can one ever have too much power?
-----------------------------------------
>It was
> designed around a 1600cc vw, but others have
installed
> c-85/O-200, Jabiru, Subaru, etc, up to about
135hp.
> Mine was powered by the humble VW for 240 hrs or
so,
> then switched over to a turbocharged Subaru EA81.
> Performance increased significantly, and no more
50 hr
> valve jobs req'd.
-------------------------------------------------------------
At 200lbs the weight of a 13b-aluminum is equal to
the ea81 with significantly
more power.
Any clue the VNE of the dragonfly airframe? (cant
find it on google)
------------------------------------------------------------
> There was one fellow out near Mojave somewhere
that
> had built a single-rotor powerplant for the DF. I
> visited his hangar back in the mid-90's. I have
no
> idea if it ever flew with that engine.
-------------------------------------------------------------
I have a farm I bought to put a fabricaton shop on
that is 2500 feet long, I
hope to be able to get in and out with the
dragonfly.
The extra power will help to leap off the ground,
but I will have to deal with
a hot landing...... Again the flaperon idea may
help.
Thanks,
Brent Hasty
Brent,
Vne on the Dragonfly is 180 mph. Clean examples can
already hit 160mph with a VW. A proper 13B would have
at least 3x the power of the VW, but would be of very
limited use in that airframe.
My EA81T setup weight 215 lbs wet, firewall forward
less prop. This included oil, coolant, rad, etc. I'm
sure an aluminum 13B would save significant weight,
but would still be far heavier than a typical O-200,
which is considered max for this aircraft. Also
consider the aluminum 13B engine cost would likely
exceed the total value of the aircraft.
Roger.
The housings run $1500 each or $4500 for the set.
The rest of the parts can be had for less than $2000 new.
So you are looking at $6000 for the motor. Add $3000 for the
PSRU. $9000 total is a far cry from the cost of an overhauled
O-200 if you can find one that does not have a bunch of
hours on at least some of its parts. There are no new O-200's.
Also the rotary is now far far cheaper to overhaul.
The 100 HP O-200 weighs 170 pounds. Add another 30 to 40 pounds for
the stuff you need firewall forward and you are not that far
off from the 260 pounds firewall forward for an all aluminum
13B rotary.
No question if you just want to fly putting a used O-200
(they are all used) in is the easier way to go. Takes less time.
The cost is about the same. However where is the creativity
and challenge in that? The rotary will be much smoother
and less fatiguing to fly long distances.
Excess HP is best used in an airplane to enhance the take
off and climb. Particularly at high altitude airports where the
power is down to 75% or less of sea level power. Out here in the
west we have 10,000 to 14,000 foot mountains to fly over.
The top speed is proportional to the cube root of the HP. The rest
of the time you can throttle back and not use the HP.
Paul Lamar ...No rotor no motor.
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