RV-9A's wing with Rotax 914?

Looking at RV-9A's specification (weight, engine, etc.), I think a
Rotax 914 can power it very well, may give a better performance than
O-235. However, the problem is Rotax is far to light to be installed
on RV-9A.

So I just can't help thinking, well, why not a new design around
RV-9A's wing and Rotax 914. The design will be pretty much on
fuselage. The benefits of this designe of new fuselage+RV-9A
wing+Rotax 914 should be:

1) the basic empty weight should be 100-150 lbs lighter than RV-9A.
Rotax 914's wet installation weight is about 80 lbs lighter than
O-235. There should be more or less some structural weight saving from
the lighter engine installation and lighter gross weight.

2)Rotax 914 has constant 100 hp output up to 12,000 feet so it gives
more horsepower at 8000 feet than O-235.

3)The fuselage, if built in composite, can be sleeker(not necessarily
much lighter though)

Overall, lighter weight+more horsepower at altitude+sleeker fuselage
should make this new fuselage+RV-9A wing+Rotax 914 design at least as
good as RV-9A with O-235.

Prove me wrong please.

Shin Gou

"Shin Gou" wrote in message
om...
Looking at RV-9A's specification (weight, engine, etc.), I think a
Rotax 914 can power it very well, may give a better performance than
O-235. However, the problem is Rotax is far to light to be installed
on RV-9A.

So I just can't help thinking, well, why not a new design around
RV-9A's wing and Rotax 914. The design will be pretty much on
fuselage. The benefits of this designe of new fuselage+RV-9A
wing+Rotax 914 should be:

1) the basic empty weight should be 100-150 lbs lighter than RV-9A.
Rotax 914's wet installation weight is about 80 lbs lighter than
O-235. There should be more or less some structural weight saving from
the lighter engine installation and lighter gross weight.

2)Rotax 914 has constant 100 hp output up to 12,000 feet so it gives
more horsepower at 8000 feet than O-235.

3)The fuselage, if built in composite, can be sleeker(not necessarily
much lighter though)

Overall, lighter weight+more horsepower at altitude+sleeker fuselage
should make this new fuselage+RV-9A wing+Rotax 914 design at least as
good as RV-9A with O-235.

Prove me wrong please.

Shin Gou

I've had similar thoughts along the lines of sticking a 914 in either an
RV-3 or an RV-9. Why not just extend the forward fuselage to get the w/b
correct? You'd also want to verify your stability margins because the longer
forward fuselage will tend to be destabilizing. Lengthening the fuselage
will cost you some weight in additional structure, but you should still end
up with a lighter airframe that uses less fuel.

On the other hand, why not build it with the 0-235 and go flying a year or
two sooner?

KB

The plane you describe already exists - the Europa.

www.europa-aircraft.com

Faster (at altitude) and lighter than an RV9 with an O-235

Better yet, the wings unplug, and you can swap in the glider wings (ala U-2)
to cruise _really_ high :-)

Cheers,
Pete
Europa Builder (both wings)


"Shin Gou" wrote in message
om...
Looking at RV-9A's specification (weight, engine, etc.), I think a
Rotax 914 can power it very well, may give a better performance than
O-235. However, the problem is Rotax is far to light to be installed
on RV-9A.

So I just can't help thinking, well, why not a new design around
RV-9A's wing and Rotax 914. The design will be pretty much on
fuselage. The benefits of this designe of new fuselage+RV-9A
wing+Rotax 914 should be:

1) the basic empty weight should be 100-150 lbs lighter than RV-9A.
Rotax 914's wet installation weight is about 80 lbs lighter than
O-235. There should be more or less some structural weight saving from
the lighter engine installation and lighter gross weight.

2)Rotax 914 has constant 100 hp output up to 12,000 feet so it gives
more horsepower at 8000 feet than O-235.

3)The fuselage, if built in composite, can be sleeker(not necessarily
much lighter though)

Overall, lighter weight+more horsepower at altitude+sleeker fuselage
should make this new fuselage+RV-9A wing+Rotax 914 design at least as
good as RV-9A with O-235.

Prove me wrong please.

Shin Gou

Earlier, (Shin Gou) wrote:

...Prove me wrong please.

Well, I'm not in any position to prove you wrong or right, but my
opinions a

* Based on my relatively meager composites experience, making a nice
composite fuselage from scratch is several times harder than riveting
together one of Vans' fuselage kits. To get a nice shape _and_ light
weight, you find yourself drawn towards using female-molded parts like
I'm developing for the HP-24 kit sailplane fuselage. And once you get
that deep into it, you're pretty much in the business.

* Based on my personal prejudice, and on many conversations with the
aeronautic engineer who designed the wing profile for the RV-10, I
don't feel so enthusiastic about the RV-9 wing as that I'd go to the
trouble of adapting it onto a different airplane. Don't get me wrong;
the RV-9 wing is a fine solution to the original set of constraints.
But I'd prefer to start with a blank sheet, and not be constrained by
the limitations imposed on the wing by a prior fuselage design.

* Based on other personal prejudices, I prefer airplanes that are
generally relatively homogenous in terms of construction methodology.
That is, metal fuselages with metal wings, and composite fuselages
with composite wings. Sure, there are often compelling reasons not to
hold with that - the HP-18 kit sailplane is a good counterexample. But
I think that people do better work, and enjoy it more, when they're
not always "shifting gears" and re-climbing learning curves as they
change between metal techniques and composite techniques.

And again, those are just my opinions.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

(Bob Kuykendall) wrote in message
Well, I'm not in any position to prove you wrong or right, but my

* Based on my personal prejudice, and on many conversations with the
aeronautic engineer who designed the wing profile for the RV-10, I
don't feel so enthusiastic about the RV-9 wing as that I'd go to the
trouble of adapting it onto a different airplane. Don't get me wrong;
the RV-9 wing is a fine solution to the original set of constraints.
But I'd prefer to start with a blank sheet, and not be constrained by
the limitations imposed on the wing by a prior fuselage design.


Bob, could you tell me more about the constrains of the RV-9A wing on
its current fuselage?

I like Rotax 914/912s and Jabiru 3300 for their light weight and fuel
efficiency. If a lighter and better engine can do the same job as an
O-235, why not?

BTW, I like Europa very much too. Actually I was going back and forth
between Europa and RV-9A. THe only problem of Europa for me is its
price: near $29k for a complete kit while RV-9A's wing kit costs only
$5400. I am just wondering why there's no head-to-head comparison
between these two aircrafts whose missions and performances are so
similar.

Shin

Earlier, (Shin Gou) wrote:

Bob, could you tell me more about the constrains of the RV-9A wing on
its current fuselage?

An RV builder who is familiar with both RV-6 and RV-9 could tell you
more about that than I ever could.

In specific, I can only repeat some of what I've heard that seems to
make sense. That is, that the longitudinal location of the RV-9 spar
is constrained lightly by the original design of the RV-6 fuselage
(elements of which of course Vans is at liberty to change) and
constrained more tightly by the size and shape of the pilot and their
relationship with the seat and controls. A similar fuselage design
will have similar general constraints - but the devil is in the
details.

I like Rotax 914/912s and Jabiru 3300 for their light weight and fuel
efficiency. If a lighter and better engine can do the same job as an
O-235, why not?

Having spent well into the five digits on composite aircraft tooling
and with the end barely on the horizon, here's the one bit of specific
advice I feel qualified to give:

If the RV-9 is anywhere near what meets your needs, buy the kit and
build it as shown in the plans. Take the extra money you would have
spent developing a new fuselage, and put it in the bank. It will way
more than cover the extra fuel burned by the O-235. The O-235 might
seem old-tech and sound like a tractor. But its extra oomph below
10000 feet will make more difference than you might expect in how the
airplane feels like it performs.

You will have the good feeling that comes from building airplane
parts, and you will not have the many sleepless nights that come from
wondering whether something you are developing is going to work as
planned. Be guided by the hand; your building experience will be
happier, quicker, and more peaceful if your mind is at ease and your
fingers are busy.

Thanks, and best regards to all

Bob K.
http://www.hpaircraft.com/hp-24

Shin Gou wrote:

Overall, lighter weight+more horsepower at altitude+sleeker fuselage
should make this new fuselage+RV-9A wing+Rotax 914 design at least as
good as RV-9A with O-235.

Prove me wrong please.

No right or wrong from me, but if you're going to all
that time and trouble, why not design a whole new
airframe for the envelope you intend and the performance
you want. RV wings or not, what you propose will almost
certainly take longer and be more expensive than an RV.
I'd also bet that you wouldn't see enough performance benefit
to warrant all the changes strapped to the same RV wing.

Interesting project from an engineering point of view,
but not very practical, IMO.

Dave 'clean sheet' Hyde

nauga wrote:

Shin Gou wrote:

Overall, lighter weight+more horsepower at altitude+sleeker fuselage
should make this new fuselage+RV-9A wing+Rotax 914 design at least as
good as RV-9A with O-235.

Prove me wrong please.

No right or wrong from me, but if you're going to all
that time and trouble, why not design a whole new
airframe for the envelope you intend and the performance
you want. RV wings or not, what you propose will almost
certainly take longer and be more expensive than an RV.
I'd also bet that you wouldn't see enough performance benefit
to warrant all the changes strapped to the same RV wing.

Interesting project from an engineering point of view,
but not very practical, IMO.

Dave 'clean sheet' Hyde



I'd have to agree with Dave on this one.
Using a lighter engine would allow for a lighter airframe.
AND lighter wings...

As a fer instance, look at the differences between an RV and
a Zenith Zodiac.

The Zodiac was designed around a smmaller lighter engine to good
advantage.

Richard

What would happen if you put an RV wing on the Zodiac XL? Would the thinner RV
wing provide less drag....therefore higher speeds?

VideoFlyer wrote:

What would happen if you put an RV wing on the Zodiac XL? Would the thinner RV
wing provide less drag....therefore higher speeds?

Well, considering the differences in chord, span and thickness,
my guess is - it won't fit.


Well duh.