KR> Tandem seating PT II

[Dan Heath]

I just happen to have a Long EZ project sitting in my hangar, including
plans.  The foam and glass priced out at around $3000 and that is what the
person who owns it, is asking for it.  If interested, go to the link below
and click on e-mail Dan.

See N64KR at http://KRBuilder.org - Then click on the pics 
See you at the 2009 - KR Gathering in Mt. Vernon, Ill
There is a time for building and a time for FLYING and the time for Flying
has begun.
Daniel R. Heath - Lexington, SC

-Original Message-
From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf
Of Marty Martin
Sent: Tuesday, May 26, 2009 5:38 PM
To: KRnet
Subject: Re: KR> Tandem seating PT II

Dustin

Don't forget.  You can find a VariEze that needs finishing and go to town
and finish it.  I had one and liked it very much. But the wife did not like
sitting behind me.  Go figure.

Greg Martin

On Mon, May 25, 2009 at 9:23 PM, dustin Reves <sre...@hotmail.com> wrote:

>
> 1. I feel like the decreased width of the airplane will benefit in making
> it as slippery as possible. obviously something 44" wide is gonna be
harder
> to push through the air than something 30 inches wide.
>
> 2. The tandem seating just feels sporty to me. Much more like sitting in a
> fighter plane than a cross country cruiser. Well, doesn't everybody wanna
> feel like they are flying a fighter?
>
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KR> Tandem seating PT II

[James Millar]

Dustin, don't overestimate the aerodynamic benefits to this. For one thing, 
the form drag of the fuselage is only a portion of the total drag. You have 
to consider that the KR2 is already a pretty slick airplane. Induced drag 
from the wings accounts for a fair bit, and then you have skin friction. You 
are probably going to end up with an increase in wetted surface which will 
remove a lot of the benefit from the reduced form drag. Also, the structure 
is going to end up heavier (almost inevitably, you are carrying more load 
further from the spar) which increases wing loading, leading to higher 
induced drag.

As everyone else has pointed out, the CG issue will be relevant - but it 
matters to drag in another way too. You are going to have to optimize for 
one condition, meaning that in other conditions, you end up with a 
considerable amount of trim, and the resultant extra drag. (If you put the 
passenger on the CG, the passenger won't change the trim that much... but 
now your pilot is way behind so a change in pilot weight will have a larger 
effect)

I'm not much good with this aerodynamics stuff, so if I've messed things up, 
I'm sure those who are will clear up my mistakes.

James



>1. I feel like the decreased width of the airplane will benefit in making 
>it as slippery as possible. obviously something 44" wide is gonna be harder 
>to push through the air than >something 30 inches wide.
>
 

KR> Tandem seating PT II

[Marty Martin]

Dustin

Don't forget.  You can find a VariEze that needs finishing and go to town
and finish it.  I had one and liked it very much. But the wife did not like
sitting behind me.  Go figure.

Greg Martin

On Mon, May 25, 2009 at 9:23 PM, dustin Reves  wrote:

>
> 1. I feel like the decreased width of the airplane will benefit in making
> it as slippery as possible. obviously something 44" wide is gonna be harder
> to push through the air than something 30 inches wide.
>
> 2. The tandem seating just feels sporty to me. Much more like sitting in a
> fighter plane than a cross country cruiser. Well, doesn't everybody wanna
> feel like they are flying a fighter?
>

KR> Tandem seating PT II

[Fred Johnson]

I'm going to throw my 2 cents worth in on this since I had thought about a
tandem in my early stages. Besides what Langford has already mentioned you
have two other issues to contend with, one) to handle the CG you have to use
a wider wing chord, that means more drag and more importantly unknown flight
characteristics, I.E; CG issues. Two) although the KR2 and 2s wings provide
plenty of lift, because a tandem has CG issues to contend and you need a
wider chord to help with those, the amount of work needed didn't offset any
gains acquired. The weight and drag penalties from the design wouldn't make
it any better an airplane the KR2 already is.

I'm not saying it CAN'T be done, just more work than it is worth. Obviously
someone with aeronautical degree would have more luck with it than those of
us who don't. look at the RV4 and 8 and you can see it's possible but there
are far more RV6's flying than the former.

Just my two cents.

Fred Johnson
Reno, NV


Mark L wrote:

People are always cautioning against modifying the design and how much 
longer it will take to accomplish.  The tandem thing would be the ultimate 
shot to the head as far as time-to-complete is concerned.

Why not think about the Sonerai II, and get on with building, if you must 
have a tandem two-place?



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KR> Tandem seating PT II

[Dan Heath]

OR, the KR1.  You did not mention the requirement to carry a passenger.

See N64KR at http://KRBuilder.org - Then click on the pics 
See you at the 2009 - KR Gathering in Mt. Vernon, Ill
There is a time for building and a time for FLYING and the time for Flying
has begun.
Daniel R. Heath - Lexington, SC

-Original Message-
From: krnet-boun...@mylist.net [mailto:krnet-boun...@mylist.net] On Behalf
Of dustin Reves
Sent: Tuesday, May 26, 2009 12:24 AM
To: KRNET LIST POST
Subject: KR> Tandem seating PT II

Perhaps I should be looking at other designs?

KR> Tandem seating PT II

[dustin Reves]

Did this so it would be easier to read

OK after thinking about the tandem seating Idea for a few days I feel
like it  will be a little bit harder than I thought it would... But
based on my limited knowledge of aerodynamics, and a few basic
assumptions, this might still be worthwhile. Obviously I would like to
get the maximum performance out of my project that I can. There are 2
reasons that I am fixated on the tandem seating arrangement. 

1.
I feel like the decreased width of the airplane will benefit in making
it as slippery as possible. obviously something 44" wide is gonna be
harder to push through the air than something 30 inches wide.

2.
The tandem seating just feels sporty to me. Much more like sitting in a
fighter plane than a cross country cruiser. Well, doesnt everybody
wanna feel like they are flying a fighter?

The drawbacks are the
rather large adjustments that will have to be made to the airframe. Im
thinking the wing will have to be moved  back. The front passenger will
have to sit somewhere right on top of the foreward spar. while the
pilot (rear) will basically be sitting  directly on the trailing edge
of the wing. I havent done the math(nor do I know how to ) but this is
definately going to necessitate moving the firewall foreward. If I
follow the suggestions of previous builders(Mark L) and use the full
length of longeron material provided in the boat kit I think I will
have enough material to massage the dimensions around enough to get the
aircraft to be able to balance properly. There are only 2 pictures
available of the only flying kr I know of with tandem seating. There is
very little daetail on the modifications done to make it fly properly,
so I am kind of just winging it and theorizing right now.   Am I just
dreaming and making this more difficult than it should be? If I had the
finances I would be looking at something like the thunder mustang, but
of course I dont(as so few of us do). Perhaps I should be looking at
other designs?

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KR> Tandem seating PT II

[dustin Reves]

OK after thinking about the tandem seating Idea for a few days I feel like it  
will be a little bit harder than I thought it would... But based on my limited 
knowledge of aerodynamics, and a few basic assumptions, this might still be 
worthwhile. Obviously I would like to get the maximum performance out of my 
project that I can. There are 2 reasons that I am fixated on the tandem seating 
arrangement. 

1. I feel like the decreased width of the airplane will benefit in making it as 
slippery as possible. obviously something 44" wide is gonna be harder to push 
through the air than something 30 inches wide.

2. The tandem seating just feels sporty to me. Much more like sitting in a 
fighter plane than a cross country cruiser. Well, doesnt everybody wanna feel 
like they are flying a fighter?

The drawbacks are the rather large adjustments that will have to be made to the 
airframe. Im thinking the wing will have to be moved  back. The front passenger 
will have to sit somewhere right on top of the foreward spar. while the pilot 
(rear) will basically be sitting  directly on the trailing edge of the wing. I 
havent done the math(nor do I know how to ) but this is definately going to 
necessitate moving the firewall foreward. If I follow the suggestions of 
previous builders(Mark L) and use the full length of longeron material provided 
in the boat kit I think I will have enough material to massage the dimensions 
around enough to get the aircraft to be able to balance properly. There are 
only 2 pictures available of the only flying kr I know of with tandem seating. 
There is very little daetail on the modifications done to make it fly properly, 
so I am kind of just winging it and theorizing right now.   Am I just dreaming 
and making this more difficult than it should be? If I had the finances I would 
be looking at something like the thunder mustang, but of course I dont(as so 
few of us do). Perhaps I should be looking at other designs?



_
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