My plan was
to pull from the radiator
scoop of the Sam james rotary cowl. Do you think this area would be
pressurized sufficiently at high speeds? Any significant effect on
radiator performance?
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Al
Gietzen
Sent: Tuesday,
February 16, 2010
11:28 AM
To: Rotary motors in aircraft
Subject: [FlyRotary]
Re: Air Pump
Before we
get too excited about putting
leaf blowers under the cowl; you might consider this. The baseline
case
here (no blower) is with the plane standing still with at sharp edge
intake at
the TB – correct? Fairly significant inlet pressure loss for that
configuration.
You may
get a similar increase in manifold
pressure by putting a nice bell-mouth entrance on the TB. And you will
get a
similar increase in manifold pressure with a ram inlet scoop flying at
about
160 Kts.
-----Original
Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
On Behalf Of Dennis
Haverlah
Sent: Monday, February
15, 2010
7:58 PM
To: Rotary motors in aircraft
Subject: [FlyRotary]
Re: Air Pump
Bill:
Thanks to my younger brother who was brave enough (use younger brothers
for
dangerous stuff) to operate the leaf blower I ran the leaf blower test
for the
group. I used a fairly new hand held Echo leaf blower Model PB 251
I "borrowed" from my neighbors hangar.
Specs - 25 cc 2 stroke,
Average Air
Volume (cfm-pipe)
|
|
Average Air
Volume (cfm-housing)
|
|
Maximum Air
Speed (mph-pipe)
|
|
No information on rpm's at these data points were listed. I would
guess
that the 2 stroke engines are operated between 6000 and
8000 rpm. but I'd like to have real rpm data.
Four tests were conducted as shown below. Local air pressure was 30.2
in
Baro. - 0.5 in for 1000" = 29.7 in hg. air pressure at field elevation.
Weather was Clear, low humidity and 53 deg. OAT. All tests were at WOT.
Pictures are attached for each test. Note the 180 deg. bend in the
Scat
tubing during the (C) test.
The (C) test picture was taken after we had taken the Scat tube but my
brother
was holding it in place.
Test condition
Static max. RPM Manifold
Pressure Engine Temp.
(A) Standard intake,
5870
28.9
Barely warm
air filter etc.
(B) W/O air filter &
5660
28.7
Fully
warm
prop blast
(C) Leaf Blower full
5925
29.9
Fully warm
throttle into throttle
body - 180 deg turn.
(D) Same as (A)
5700
29.0
Fully warm
It appears that the blower raised the inlet pressure by 1.2 in Hg. and
the
engine rpm increased from 5700 to 5925 rpm.
I needed to turn the mixture knob slightly richer with the blower
running to
get max. power.
Also note that the tube feeding the intake had to make a 180 deg. bend
just
before the throttle body.
The leaf blower used in this test was the smallest Echo makes.
Their web site lists approximately 15 blowers and the largest is a 63.3
cc 2
stroke as follows:
Average Air
Volume (cfm-pipe)
|
|
Average Air
Volume (cfm-housing)
|
|
Maximum Air
Speed (mph-pipe)
|
|
My thought is that several blowers are available that probably would
provide
the needed blower capacity.
I believe we need a system that is adaptable to using Tracy'c RD-1
drive.
I also believe it is not likely a centrifugal blower can be placed
between the
engine and gear box because the spacing between the gear box plate and
the
engine is about 2.5 inches and the ring gear is approximately in the
middle of
the space. If someone is interested in adding a direct drive
blower
why not attach it to the rear of the engine with the centrifugal fan
attached
to the crankshaft pulley? The fans from the big blowers
may have enough capacity to work at our crankshaft speeds. If this
could
be made to work it would fit the majority of the rotary installations
and be an
inexpensive way to add More Power Scotty.
PS I have all the power I need with my DIE intake - if someone can find
a way
to build it that may solve most of the power needs.
Dennis Haverlah
Bill Bradburry wrote:
Has anybody ever
tried hooking up a leaf
blower to the throttle body inlet and see what that would do to the
static rpm
and manifold pressure at WOT?