Pipers/Strutural Engineering/Doors

[EDR]

The only single-engine piston aircraft that I can think of that Piper
has put a door on each side of the fuselage is the Tomahawk.
Except for the addition of a couple wing ribs for wing walk area and a
door frame, are there any structural reasons why a pilot side door
could not be added? Now that Piper has gone to the overhead panel, the
left sidewall is clear of any "controls". (Is the fuel selector still
there? It could be relocated to the center console as it is on the
Saratoga.)

[Mike Rapoport]

It adds more weight than you might think. The area around the door has to
be reinforced. Make a paper box and feel how stiff it becomes when you tape
the final side and then cut a jarge hole on one side and note how much
stiffness it loses.

Mike
MU-2


"EDR" > wrote in message
...
> The only single-engine piston aircraft that I can think of that Piper
> has put a door on each side of the fuselage is the Tomahawk.
> Except for the addition of a couple wing ribs for wing walk area and a
> door frame, are there any structural reasons why a pilot side door
> could not be added? Now that Piper has gone to the overhead panel, the
> left sidewall is clear of any "controls". (Is the fuel selector still
> there? It could be relocated to the center console as it is on the
> Saratoga.)

[Paul Tomblin]

In a previous article, EDR > said:
>Except for the addition of a couple wing ribs for wing walk area and a
>door frame, are there any structural reasons why a pilot side door
>could not be added? Now that Piper has gone to the overhead panel, the

There is a company that has an STC for a pilot side door for the AzTruck.
(They also do a float conversion, beleive it or not.) I believe they do a
lot of structural reinforcement of the fuselage as well.


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[Ron Natalie]

"Mike Rapoport" > wrote in message ink.net...
> It adds more weight than you might think. The area around the door has to
> be reinforced. Make a paper box and feel how stiff it becomes when you tape
> the final side and then cut a jarge hole on one side and note how much
> stiffness it loses.
>
Yes. It's pretty amazing what a hole does to the strength. I have a baggage
door mod on my Navion (it was a factory option). There are extra structural
members and a zillion rivets to support a foot square hole in the side.

-Ron

[EDR]

In article et>, Mike
Rapoport > wrote:

> It adds more weight than you might think. The area around the door has to
> be reinforced. Make a paper box and feel how stiff it becomes when you tape
> the final side and then cut a jarge hole on one side and note how much
> stiffness it loses.

I understand the torsional rigidity issue.
Cessna does it, suspending the fuselage from the wing.
Beech did it with the Musketeer line.
I would think the wing on the bottom would make it easier because the
wing center section spar box and not the fuselage structure is not
carrying the load.
How much weight are we talking about? 25 pounds?
The weight's of Pipers and Cessna's seem pretty comparable across the
product lines.

Is the question more one of economics?

[Neil Gould]

Recently, EDR > posted:

> The only single-engine piston aircraft that I can think of that Piper
> has put a door on each side of the fuselage is the Tomahawk.
>
How about the Pacer / Tri Pacer?

> Except for the addition of a couple wing ribs for wing walk area and a
> door frame, are there any structural reasons why a pilot side door
> could not be added?
>
There would have to be a considerable amount of fuselage stiffening added
to the pilot side. That would add quite a bit of weight, reducing the
useful load and performance.

> Now that Piper has gone to the overhead panel, the
> left sidewall is clear of any "controls". (Is the fuel selector still
> there? It could be relocated to the center console as it is on the
> Saratoga.)
>
The fuel selector is under the dash area, ahead of where a door cutout
would be. I don't think that's the big problem that's kept Piper away from
dual doors.

Neil

[john smith]

Neil Gould wrote:
>
> Recently, EDR > posted:
> > The only single-engine piston aircraft that I can think of that Piper
> > has put a door on each side of the fuselage is the Tomahawk.

> How about the Pacer / Tri Pacer?
Doesn't count... I am only considering low-wing monoque construction.

[John Roncallo]

EDR wrote:
> In article et>, Mike
> Rapoport > wrote:
>
>
>>It adds more weight than you might think. The area around the door has to
>>be reinforced. Make a paper box and feel how stiff it becomes when you tape
>>the final side and then cut a jarge hole on one side and note how much
>>stiffness it loses.
>
>
> I understand the torsional rigidity issue.
> Cessna does it, suspending the fuselage from the wing.
> Beech did it with the Musketeer line.
> I would think the wing on the bottom would make it easier because the
> wing center section spar box and not the fuselage structure is not
> carrying the load.
> How much weight are we talking about? 25 pounds?
> The weight's of Pipers and Cessna's seem pretty comparable across the
> product lines.
>
> Is the question more one of economics?

I would not be willing to pay 25 Lb in our clubs Archer for a second
door. I find 3 adult men and normal luggage puts me at full GW.

John Roncallo

[Mike Rapoport]

"EDR" > wrote in message
...
> In article et>, Mike
> Rapoport > wrote:
>
> > It adds more weight than you might think. The area around the door has
to
> > be reinforced. Make a paper box and feel how stiff it becomes when you
tape
> > the final side and then cut a jarge hole on one side and note how much
> > stiffness it loses.
>
> I understand the torsional rigidity issue.
> Cessna does it, suspending the fuselage from the wing.
> Beech did it with the Musketeer line.
> I would think the wing on the bottom would make it easier because the
> wing center section spar box and not the fuselage structure is not
> carrying the load.
> How much weight are we talking about? 25 pounds?
> The weight's of Pipers and Cessna's seem pretty comparable across the
> product lines.
>
> Is the question more one of economics?

With a high wing aircraft there is already additionaly structure present to
transfer the load of the wing to the gear. Of course, you are right, a
secon door adds cost. I don't know how much weight but these planes are
pretty limited already.

Mike
MU-2

[john smith]

Mike Rapoport wrote:
> With a high wing aircraft there is already additionaly structure present to
> transfer the load of the wing to the gear. Of course, you are right, a
> secon door adds cost. I don't know how much weight but these planes are
> pretty limited already.

Excellent point!
I totally didn't think of that structure.

[Jay Honeck]

> I would not be willing to pay 25 Lb in our clubs Archer for a second
> door. I find 3 adult men and normal luggage puts me at full GW.

True. But with the 1460 pound useful load of our Pathfinder (Cherokee 235)
they could easily have sacrificed 25 pounds of structural reinforcement in
exchange for the added convenience and safety.

I still believe that Piper's decision to forego the pilot-side door in the
235/236 line has proven to be a many multi-million dollar mistake for Piper
over the years.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Mike Rapoport]

How expensive would it have been to get a second door certified? I wonder
why nobody has developed a second door STC if it is so desirable and easy to
do. The whole success of the Cherokee line was based on commonality of
parts and low cost.

Mike
MU-2


"Jay Honeck" > wrote in message
news:kXPFb.633938$Fm2.569782@attbi_s04...
> > I would not be willing to pay 25 Lb in our clubs Archer for a second
> > door. I find 3 adult men and normal luggage puts me at full GW.
>
> True. But with the 1460 pound useful load of our Pathfinder (Cherokee
235)
> they could easily have sacrificed 25 pounds of structural reinforcement in
> exchange for the added convenience and safety.
>
> I still believe that Piper's decision to forego the pilot-side door in the
> 235/236 line has proven to be a many multi-million dollar mistake for
Piper
> over the years.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[EDR]

In article <kXPFb.633938$Fm2.569782@attbi_s04>, Jay Honeck
> wrote:

> I still believe that Piper's decision to forego the pilot-side door in the
> 235/236 line has proven to be a many multi-million dollar mistake for Piper
> over the years.

Yep, Cessna outsells Piper 2:1 or even 3:1, depending on the model.

[Jay Honeck]

> How expensive would it have been to get a second door certified? I wonder
> why nobody has developed a second door STC if it is so desirable and easy
to
> do. The whole success of the Cherokee line was based on commonality of
> parts and low cost.

Right, but see EDR's post. Who cares how expensive the endeavor is, if it
means you'll sell three times as many planes?

On the other hand, there's no guarantee that a second door would have
guaranteed this result -- but for many "less sprightly" pilots, the single
door is a real handicap.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Mike Rapoport]

Sure they could have sold more *if* the price was unchanged, but what if it
cost $10,000 more? The 235 was never going to sell as well as the 182 or
206 anyway which both have significant utility advantages operating
off-airport and short field.

Mike
MU-2


"Jay Honeck" > wrote in message
news:GL%Fb.633459$Tr4.1633242@attbi_s03...
> > How expensive would it have been to get a second door certified? I
wonder
> > why nobody has developed a second door STC if it is so desirable and
easy
> to
> > do. The whole success of the Cherokee line was based on commonality of
> > parts and low cost.
>
> Right, but see EDR's post. Who cares how expensive the endeavor is, if it
> means you'll sell three times as many planes?
>
> On the other hand, there's no guarantee that a second door would have
> guaranteed this result -- but for many "less sprightly" pilots, the single
> door is a real handicap.
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Jay Honeck]

> The 235 was never going to sell as well as the 182 or
> 206 anyway which both have significant utility advantages operating
> off-airport and short field.

Well, that's somewhat debatable. If you're talking about landing in
wagon-rutted fields with three-foot hedges on either side, you're right --
the 182's high wing and steel gear will beat the low wing aircraft, hand's
down.

However, it's kind of the aviation version of SUV marketing: Sure, a Hummer
can climb a 60 degree slope, but who really cares? 99.995% of the
population will drive it to the store.

Bottom line: I fly the Pathfinder in and out of grass strips that would
challenge a lesser plane. That's as "off-road" as I care to get. Heck,
that's MORE "off-road" than most pilots I know *ever* get. (D'ja ever take
your MU-2 into Amana? :-)

> Sure they could have sold more *if* the price was unchanged, but what if
it
> cost $10,000 more?

As I understand it, the 235 was already priced higher than the 182 back in
'74 -- so the chances of Piper coming in with it under-priced were unlikely.
Still, Piper sold enough 235s and 236s to make them a profitable line, and
the second door would only have helped sales.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[EDR]

In article et>, Mike
Rapoport > wrote:

> Sure they could have sold more *if* the price was unchanged, but what if it
> cost $10,000 more? The 235 was never going to sell as well as the 182 or
> 206 anyway which both have significant utility advantages operating
> off-airport and short field.

Don't confuse the issue.
Rough field operations is a prop clearance issue.
That's why the outfitters and bush pilots use taildraggers.
Mooney's aren't the smartest airplanes to operate off of grass strips
unless you know for certain they have no dips or holes.

[Kevin Darling]

john smith > wrote in message >...
> Neil Gould wrote:
> > Recently, EDR > posted:
> > > The only single-engine piston aircraft that I can think of that Piper
> > > has put a door on each side of the fuselage is the Tomahawk.
>
> > How about the Pacer / Tri Pacer?
> Doesn't count... I am only considering low-wing monoque construction.

Cherokee Six? Okay, the second one's not by the pilot though.

I've always wanted a Commander 11X because of its two doors.

Kev

[Mike Rapoport]

How much rough field experience do you have? Rough field is about prop
clearance but it is also about gear strength and low stall speeds.

Mike
MU-2


"EDR" > wrote in message
...
> In article et>, Mike
> Rapoport > wrote:
>
> > Sure they could have sold more *if* the price was unchanged, but what if
it
> > cost $10,000 more? The 235 was never going to sell as well as the 182
or
> > 206 anyway which both have significant utility advantages operating
> > off-airport and short field.
>
> Don't confuse the issue.
> Rough field operations is a prop clearance issue.
> That's why the outfitters and bush pilots use taildraggers.
> Mooney's aren't the smartest airplanes to operate off of grass strips
> unless you know for certain they have no dips or holes.

[Mike Rapoport]

"Jay Honeck" > wrote in message
news:IA1Gb.640175$Fm2.571783@attbi_s04...
> > The 235 was never going to sell as well as the 182 or
> > 206 anyway which both have significant utility advantages operating
> > off-airport and short field.
>
> Well, that's somewhat debatable. If you're talking about landing in
> wagon-rutted fields with three-foot hedges on either side, you're right --
> the 182's high wing and steel gear will beat the low wing aircraft, hand's
> down.
>
> However, it's kind of the aviation version of SUV marketing: Sure, a
Hummer
> can climb a 60 degree slope, but who really cares? 99.995% of the
> population will drive it to the store.

Agreed but if a Hummer only costs a little more (and had no other drawbacks)
then everybody will buy it instead of the other SUVs which will only climb a
40 deg slope


> Bottom line: I fly the Pathfinder in and out of grass strips that would
> challenge a lesser plane. That's as "off-road" as I care to get. Heck,
> that's MORE "off-road" than most pilots I know *ever* get. (D'ja ever
take
> your MU-2 into Amana? :-)
>
I have flown into a lot shorter and rougher fields than that! Do they have
cheap fuel?

> > Sure they could have sold more *if* the price was unchanged, but what if
> it
> > cost $10,000 more?
>
> As I understand it, the 235 was already priced higher than the 182 back in
> '74 -- so the chances of Piper coming in with it under-priced were
unlikely.

So would anyone have bought them if they were $10,000 more? We will never
know. Piper evidently thought that it wasn't worth it.

> Still, Piper sold enough 235s and 236s to make them a profitable line, and
> the second door would only have helped sales.

Again it would have helped sales at the same price but there is a limit to
how much people will pay for a feature. Saying that it is obvious that
adding another door would have helped Piper is to assume that the company
was inept.and they didn't know what their customers wanted.

Mike
MU-2

> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[EDR]

In article . net>,
Mike Rapoport > wrote:

> How much rough field experience do you have? Rough field is about prop
> clearance but it is also about gear strength and low stall speeds.

Ahhhh!!! Now we're talking rough field! Just pump up the struts on them
Pipers. But, I am guessing that structurally, what you are getting at
is the load difference in having a landing gear box structure (Cessnas)
vice the wing attachment to the spar (Pipers).

BTW, IIRC, the Mitsubushi originally advertised short and rough field
capability for the original MU-2's. Even created advertising photos
with shots of the aircraft on grass with the outdoors backgrounds.

Alas, we digress! Back to the original topic, two cockpit doors.

[Mike Rapoport]

It was you who substituted "rough" for "short"! I was just going along!

Short, rough field takoff and landing along with high cruise speed where
indeed the design goals for the MU-2. The main feature used to accomplish
these goals were full span double slotted fowler flaps. which eliminated the
room for ailerons, hence the spoilers.

Mike
MU-2


"EDR" > wrote in message
...
> In article . net>,
> Mike Rapoport > wrote:
>
> > How much rough field experience do you have? Rough field is about prop
> > clearance but it is also about gear strength and low stall speeds.
>
> Ahhhh!!! Now we're talking rough field! Just pump up the struts on them
> Pipers. But, I am guessing that structurally, what you are getting at
> is the load difference in having a landing gear box structure (Cessnas)
> vice the wing attachment to the spar (Pipers).
>
> BTW, IIRC, the Mitsubushi originally advertised short and rough field
> capability for the original MU-2's. Even created advertising photos
> with shots of the aircraft on grass with the outdoors backgrounds.
>
> Alas, we digress! Back to the original topic, two cockpit doors.

[Tom Sixkiller]

"Jay Honeck" > wrote in message
news:GL%Fb.633459$Tr4.1633242@attbi_s03...
> > How expensive would it have been to get a second door certified? I
wonder
> > why nobody has developed a second door STC if it is so desirable and
easy
> to
> > do. The whole success of the Cherokee line was based on commonality of
> > parts and low cost.
>
> Right, but see EDR's post. Who cares how expensive the endeavor is, if it
> means you'll sell three times as many planes?
>
> On the other hand, there's no guarantee that a second door would have
> guaranteed this result -- but for many "less sprightly" pilots, the single
> door is a real handicap.

'Spose it (the one door affair) ruined the Bonanza as well?

[john smith]

Mike Rapoport wrote:
> It was you who substituted "rough" for "short"! I was just going along!

"The 235 was never going to sell as well as the 182 or
206 anyway which both have significant utility advantages operating
off-airport and short field."

Actually, I substituted "rough" for "off-airport".
Short can apply to hard surface, but doesn't necessarily affect landing
gear strength.
(Just clarifying my thought process. :-)

[Mike Rapoport]

"john smith" > wrote in message
...
> Mike Rapoport wrote:
> > It was you who substituted "rough" for "short"! I was just going along!
>
> "The 235 was never going to sell as well as the 182 or
> 206 anyway which both have significant utility advantages operating
> off-airport and short field."
>
> Actually, I substituted "rough" for "off-airport".
> Short can apply to hard surface, but doesn't necessarily affect landing
> gear strength.
> (Just clarifying my thought process. :-)

OK