More on 40/60/90 Pattern

[randy hatfield]

Well, I finally got around to weighting the Venus today and tried some
different props on the Saito 72.

Right now the Venus 40 weighs 5 1/3 pounds.  It is a little heavier than
normal, as I lost the stock prop nuts/spinner for the Saito 72 due to a lean
out. I can tell as it is more nose heavy than before.  Anyway I would guess
at a 5 1/4 pounds for the normal weight.  This is reasonable for a 40 sized
ARF.

I fly Magnum YS blend which is 22/20 fuel with this engine.  I was flying
with an APC 12X8.  I got 9860 RPM on the ground.  With this prop the Venus
is very fast and you have to fly fast to keep the energy level up.  On the
stall turn with full roll and half square loop with half roll, you are
running out of energy at the top.  P-factor becomes very high and keeping
the plane from yawing left is very difficult.

I tried out a Bolly clubman series 13.5X6 this evening.  I got 9660 on the
ground.  Lost 200 RPM; but gained a much better flying plane.   The plane
flies a lot slower on this prop; and the engine idles better.  This
translate to much more constant speed during the routine and more time
between maneuvers.  I still have enough energy in the stall turn with full
run and half square with half roll to still continue in straight vertical
flight after the roll.    Vertical is still not unlimited but enough for the
intermediate routine and more than enough for sportsman.

I plan of flying the 13.5X6 as my main prop on the plane from now and use
the 12X8 for my windy day prop when more speed is needed.

I is a very good combo for someone starting out in pattern.  They could fly
it in sportmans with standard servos and an OS46FX to try pattern out.  Then
move up to a for stroke and better servos if they like pattern.  If they do
not like pattern then they still have a very nice burn holes in the sky
plane.

Randy Hatfield
AMA 453495
NSRCA 2422

-----Original Message-----
From: Ihncheol Park [mailto:PatternFlyer at msn.com]
Sent: Friday, September 06, 2002 4:01 PM
To: randy10926 at earthlink.net
Subject: RE: More on 40/60/90 Pattern


Randy,
can you tell me the weight of your Venus 40 with Saito 72?
If possible the size of prop and rpm would be also great.
I fly intermediate with a 9lb BeatOn90 with YS91AC.  It flame out if I try
to keep the vertical too long. Otherwise I haven't had any problem flying
the entire sequence.
I just got a YS 63 for my EZ BeatOn 50, but will probably build another kit
for the engine.
thanks,

Ihncheol

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of hatfield
Sent: Friday, September 06, 2002 8:42 AM
To: discussion at nsrca.org
Subject: Re: More on 40/60/90 Pattern


I am using a Saito 72 in a GP Venus 40.  I fly intermediate.  The power is
sufficient but the full roll does take a lot of stream of out the vertical.
I
had a Tracer Kit lying around, so I am building to use with the saito 72.
It
will be my other plane, as I have a Focus also ( as soon as I replace the
engine mount).

I was thinking of building a 25% enlargement of the tracer to go with a OS
1.20 Surpass II pumper I have laying around.  But that is probably a winter
project.

Randy Hatfield

On Fri, 6 Sep 2002 08:00:04 EDT mrstev0922 at aol.com wrote:

> Jean,...
>
> In your post, you mentioned building a plane
> for your Saito 72.  I just
> wanted to offer you my experiences with this
> very same engine.
>
> >
>
> This past year I flew a modified Tower 40 Kaos
> powered by the Saito 72 in
> Intermediate category.  I built the plane as
> light as possible with
> Retracts!!  Even with retracts my plane only
> weighed 5 1/2 pounds.  I didn't
> use any lite ply in the plane at all.  I made a
> balsa/fiberglass laminate for
> fuselage doublers and formers.  I also replaced
> all the kit wood with light
> weight contest grade balsa.
>
> Anyway,... with wing span of 56 inches and a
> wing area of around 545 squares
> I thought the plane had all the power in the
> world.  However those who
> watched it fly and judged me at contest thought
> the plane was still
> underpowered and struggled in the vertical.
> Don't get me wrong,... the plane
> would go vertical forever, but to do a full
> roll in a stall turn or any
> vertical manuver and still have power to "cap
> off the top" was asking a bit
> much.
>
> My gut reaction to the plane you proposed for
> your Saito 72 is its too big
> for that engine if you are going to compete
> competitvely with it, especially
> in Advanced!!  For what it worth, that's just
> my opinoin.  A lightly built
> Tracer (five pounds or less) would be awesome
> with this engine as the
> airframe is a bit smaller and you'd have gobs
> of extra power for the top of
> tall vertical manuvers.
>
> Sincerely,
> Steve Teerlinck
> Monson, Massachusetts
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