Today's Message Index:
----------------------
1. 06:00 AM - Re: RV7A vs RV9A (Rafael)
2. 07:52 AM - Re: Initial biuld decisions (Michael D. Cencula)
3. 09:14 AM - Re: Initial biuld decisions (sportypilot)
4. 09:04 PM - Re: Initial biuld decisions (Carl Peters)
Message 1
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James,
I'm in Aiken, SC. I would absolutely love to take a look at the projects
and would gladly pay all expenses for a ride in an RV. I'm retired, so any
time any day is convenient for me.
My decision once more changes to the 9A over the 7A. Last night a voice
kept telling me: Keep It Simple Stupid! After running a spread sheet with
the number$, a 9A with a fixed pitch prop, and an O-320 engine would plenty
of airplane for me.
My cell # (803)292-7410
_____
From: owner-rv7-list-server@matronics.com
[mailto:owner-rv7-list-server@matronics.com] On Behalf Of James Clark
Sent: Wednesday, May 09, 2007 11:12 PM
Subject: Re: RV7-List: RV7A vs RV9A
Rafael,
Where is SC are you?
If you are ever in the Columbia area, we probably can arrange for you to see
an RV9A, RV6's, maybe RV7A, several RV7s under construction, an although you
did not reference such maybe an RV4 under construction and an RV10 just
getting started. Probably could rustle up a ride as well.
Now to your questions ... I think you have received good answers already but
ask yourself the following ...
1. Will MOST of my flying be cross-country?
2. Will I EVER want to do aerobatics?
Both planes fly quite nicely. The stick forces on the 9(A) is a bit
"heavier" as you get farther into the roll to one side or the other but it
still flies "like an RV".
James
On 5/9/07, Rafael <rafael@gforcecable.com> wrote:
Although I've been flying for over 29 years, I'm about to become a new
builder. I'm evaluating the merits of the RV9A and the RV7A. My interests
are for an airplane that would carry my wife and I on trips from South
Carolina to the Midwest and occasionally to the West coast. Aerobatics are
not a priority, although, if I build the 7, I would like to dip my toe into
this type of flying.
A couple of questions:
Which airplane makes a better IFR platform? I imagine that the 9 would
probably be less responsive (more stable?). Would the 7 behave better in
the bumps (higher wing loading).
If I build the 7, the 180hp, not available in the 9, would get you higher
faster.
For the long trips, I would like to add fuel capacity. What's the added
cost and weight of adding tip tanks? I've heard of 8.5 gal, giving 55 gal
total. Would putting tip tanks on the 7 limit its aerobatic capabilities?
This is my first post, so please let me know if this is the kind of
questions appropriate for this forum.
Thanks and best regards,
Rafael
http://www.matronics.com/Navigator?RV7-List
http://forums.matronics.com
james@nextupventures.com .
Message 2
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| Subject: | Re: Initial biuld decisions |
I've been wondering some of the same things as Rafael, but would like to add
one more question:
When selecting an engine, does the choice of fixed pitch vs CS have any
bearing on choosing Dynafocal I vs. Dynafocal II?
I read a posting on this list that indicated Dynafocal II was intended for CS
props. The argument was that the center of mass is further forward on a CS
installation, so the focus of the mounts is further forward to match that and
reduce vibration.
Is this actually true? I've been able to find no other info to back this up,
although I have found quite a few people flying Dynafocal I motors with CS
props (which would seem to contradict the posting).
The posting is here in case anyone wants to read it:
http://www.matronics.com/searching/getmsg_script.cgi?INDEX=5148244?KEYS=dynafocal_&_engine_&_code?LISTNAME=RV?HITNUMBER=8?SERIAL=07422721769?SHOWBUTTONS=YES
Thanks,
Mike Cencula
On Saturday May 12 2007 04:10 pm, Rafael wrote:
> First of all, I thank all who provided me with input in making the decision
> between a 9A and 7A. I have decided to build the 7A. It has not been an
> easy decision. Basically the balance tilted towards the 7 after
> considering the Vne and the added performance with the 360 engine.
>
>
> Now I would like help with a couple of other decisions. First, IO-360 vs
> O-360. I was leaning heavily towards the injected engine, carburetor heat
> being the issue. However, after attending an EAA meeting this morning and
> talking to an RV-8 builder with a beautiful 8A with an O-360, I'm no longer
> sure. What advantages does the fuel injection have? Performance?
> Reliability? Ease of installation? Maintenance? Any other? I believe
> cost and weight penalty are close for either engine.
>
>
> The other decision is between Constant Speed and Fixed Pitch prop. It is
> my understanding that the CS will provided better takeoff and climb figures
> and marginally better cruise performance. I'm wondering if this
> performance is worth the extra $6500 or so for the CS. I'm leaning towards
> the FP implementation, but I would like to hear comments.
>
>
> Thanks and best regards to all,
>
>
> Rafael
Message 3
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| Subject: | Initial biuld decisions |
Dynafocal I is the standard engine case type where the engine connects
To the engine mount, conical is the older style engine cases and they
Can be converted to dynafocal I for about 400.00 at places like ECI,
Dynafocal II was an oddball engine type done on a few factory type
Aircraft, these choices have nothing to do with CS or fixed pitch
Crankshafts, those differences are only if the crankshaft has a
Hollow end on the crankshaft.. Vans sells all three mounts,but they
Will Make you sign a not return form for the conical or Dynafocal II
Engine mounts.. I would stick with the dynafocal I mount and you still
Can buy an engine that has the hollow crankshaft and use a fixed pitch
Prop (it takes plugs in the end of the crank) and later you can move
Up to constant speed prop when you can afford it.. having options is
A good thing.. these items are in the preview plans.. if you have them
Danny..
I've been wondering some of the same things as Rafael, but would like to
add
one more question:
When selecting an engine, does the choice of fixed pitch vs CS have any
bearing on choosing Dynafocal I vs. Dynafocal II?
I read a posting on this list that indicated Dynafocal II was intended for
CS
props. The argument was that the center of mass is further forward on a CS
installation, so the focus of the mounts is further forward to match that
and
reduce vibration.
Is this actually true? I've been able to find no other info to back this
up,
although I have found quite a few people flying Dynafocal I motors with CS
props (which would seem to contradict the posting).
The posting is here in case anyone wants to read it:
http://www.matronics.com/searching/getmsg_script.cgi?INDEX=5148244?KEYS=dyna
focal_&_engine_&_code?LISTNAME=RV?HITNUMBER=8?SERIAL=07422721769?SHOWBUTTONS
=YES
Thanks,
Mike Cencula
On Saturday May 12 2007 04:10 pm, Rafael wrote:
> First of all, I thank all who provided me with input in making the
decision
> between a 9A and 7A. I have decided to build the 7A. It has not been an
> easy decision. Basically the balance tilted towards the 7 after
> considering the Vne and the added performance with the 360 engine.
>
>
> Now I would like help with a couple of other decisions. First, IO-360 vs
> O-360. I was leaning heavily towards the injected engine, carburetor heat
> being the issue. However, after attending an EAA meeting this morning and
> talking to an RV-8 builder with a beautiful 8A with an O-360, I'm no
longer
> sure. What advantages does the fuel injection have? Performance?
> Reliability? Ease of installation? Maintenance? Any other? I believe
> cost and weight penalty are close for either engine.
>
>
> The other decision is between Constant Speed and Fixed Pitch prop. It is
> my understanding that the CS will provided better takeoff and climb
figures
> and marginally better cruise performance. I'm wondering if this
> performance is worth the extra $6500 or so for the CS. I'm leaning
towards
> the FP implementation, but I would like to hear comments.
>
>
> Thanks and best regards to all,
>
>
> Rafael
Message 4
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| Subject: | Re: Initial biuld decisions |
I posted this on the RV-9 list as you posted your query there, too.
Rafael,
A couple things:
1) Regarding Vne and the O-360, it shouldn't be a big deal with the
RV-9. There are quite a few O-360 powered -9's out there, and you won't
flirt with Vne in cruise. The only time it would be an issue is in a
dive/descent, a small part of your time flying. One will need to watch
for Vne with both the O-360 or O-320 in a descent - the former will make
it a bit easier to get close in a more shallow descent. Just throttle
back, that's it. The attention to this is no different than other
critical areas of flight, such as the landing.
2) Between the O- and IO-360, there are many threads on this in the
archives for the various forums. Weight will be a non issue. The
injected models main advantage IMHO is to run lean of peak and achieve 1
gph improvement in fuel burn. A more balanced fuel mixture to each
cylinder is possible. You don't have to worry about carb icing. But,
there is some complexity, higher fuel line pressures, need for a return
fuel line to a tank and more expensive fuel selector, more difficult hot
starts. There are others on these forums that have much more real world
info since I'm still a builder.
3) FP vs CS prop - this is one of the the top three debates that rage
amongst the OBAM market (along with to prime or not, slider vs tip-up,
etc). I'm still deciding on that one, and have a year still to worry.
Frankly, I'm leaning toward an FP - lighter weight, MUCH cheaper, less
maintenance/overhaul issues. Craig Catto builds a beautiful 3 blade prop
that I have flown behind in a -9 - smooth, excellent craftmanship, and
costs $1800. He (and other manufacturers) can set you up with a prop
that is coarse pitched that will give you Van's cruise numbers.
Comparing performance numbers from various builders shows cruise numbers
about equal between a properly configured cruise FP vs a CS. You will
sacrifice climb rate/takeoff distance a bit, so if you fly into hot and
high or short fields all the time, then you need to re-think this. But
honestly, I do all my flying in Illinois and elsewhere into airports
with at least 3500' strips - really look at Van's T/O and landing
numbers with a FP prop in the -9. There are few places where you can't
go that a CS will make a difference. On the flip side a CS resell may be
better, especially with the -7. Acro and formation flying have some
benefit with a CS. One thing against the FP is slowing down and descent
rate. Coming into the pattern and trying to slow down takes a little
more forethought and earlier energy management with the FP, since the CS
can give a little drag when in fine pitch and help out. This is
particularly so with the -9. Basically, I think the argument is a little
silly, as some practice will make you competent. I fly a Dakota with a
CS, but have no trouble when I grab the glider-like Diamond DA-20 with
FP after practicing with it a little once or twice. So, for me, I'll
likely go with the FP and use the $5000 saved over the CS for about 1500
gal of avgas. That's quite a few cross-country trips!
Carl
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