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

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

(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

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.

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


Well duh.

Dang...there go my plans for this weekend! LOL!

I realize that it wouldn't fit. I guess my question is more along the lines
of:

"With a thinner wing, more like the one on an RV, would the Zodiac XL have
higher speeds? (both cruise and stall?)

Or more simply, why is the XL so much slower than the RV? Is the thick wing
the MAIN reason? (I realize there are many reasons) More horsepower does not
necessarily net higher speeds. Reducing drag does.