RV-9A's wing with Rotax 914?

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.

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.

VideoFlyer wrote:

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.


Well, the Z is an 80 to 100 hp airframe.
The RV is a150 to 200 ho airframe.
That might have SOME effect on speed.

Lessee, I think the RV has a lot more wing area,
(certainly more than the HDS anyway)
But it's a lot heavier too.

That fat airfoil on the Z makes for a lighter wing structure.

Also, compare stall speeds as well as cruise speeds.

One is a bigger heavier airframe and it NEEDS more power to fly.

The other is smaller, lighter, and has a higher lift wing.

Richard

In all likelyhood the answer is yes, it would be faster, both in
cruise and stall. I've flown a Zodiac and it was not a fast airplane,
man that wing is THICK.

And to answer the question about putting the turbo normalized Rotax
engine on an RV wing. Why not just build a longer (custom) engine
mount on the standard RV airframe and redo the fiberglass cowling.
You'd end up with a lighter plane and have the CG where you wanted it.
Also the longer nose (besides looking turbine cool) will save drag
because you're getting the prop a little further from the canopy and
wing roots. And yes the longer moment arm will increase the time
required for spin recovery, but it will also make it a more stable IFR
platform in pitch and yaw.

Also, the big difference between the RV and Europa on kit price is the
amount of labor you're going to have to put in. Assuming people with
equal skill in the respective contsruction materials, you're going to
be done faster with the Europa. The Europa is top of my list right
now because my time is more limited than my budget.

Regards



(VideoFlyer) wrote in message ...
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.

On Wed, 03 Mar 2004 12:46:45 -0800, Jay wrote:

And to answer the question about putting the turbo normalized Rotax
engine on an RV wing. Why not just build a longer (custom) engine mount
on the standard RV airframe and redo the fiberglass cowling. You'd end
up with a lighter plane and have the CG where you wanted it.
Also the longer nose (besides looking turbine cool) will save drag
because you're getting the prop a little further from the canopy and
wing roots. And yes the longer moment arm will increase the time
required for spin recovery, but it will also make it a more stable IFR
platform in pitch and yaw.


Putting a lighter engine further forward will probably increase the polar
moment of inertia slightly, which would tend to very slightly slow the
aircraft's response in pitch and yaw. But from a stability point of view,
the extra area forward will have roughly the equivalent effect to reducing
the area of the vertical and horizontal stabs. Thus it will reduce the
static longitudinal and directional stability, which would make it a less
stable IFR platform.

In pitch, the fix may be to move the CG aft limit a bit forward, or
maybe it will be OK as is. In yaw, flight tests would determine whether
it was necessary to add vertical stab area, possibly via a dorsal fin.

--
Kevin Horton RV-8 (finishing kit)
Ottawa, Canada
http://go.phpwebhosting.com/~khorton/rv8/
e-mail: khorton02(_at_)rogers(_dot_)com

Jay wrote:

And yes the longer moment arm will increase the time
required for spin recovery, but it will also make it a more stable IFR
platform in pitch and yaw.

Whoa there. A longer nose moment arm will _decrease_
stability, not increase it. As for spin recovery, increasing
or decreasing depends on the weight of the engine and the
moment arm (or arm^2, technically).

Dave 'sluggo' Hyde