If you absolutely must have a GB-2, it will be very hard to find, but if you
look for essentially the same aircraft with a different engine and call it a
Staggerwing Beech, you will have reasonably good luck. Walter Beech called
it a Traveler when he brought it out in 1933 and it was in production
through the war, when the Navy called the D17 a GB-1 or GB-2 and gave it
slightly different R-985 engines. In other military branches, it was the
UC-43.
Here is a D17S for sale in California:
http://www.eaa1279.org/Member%20Photos/MPhGrangerHaugh/MPGrangerNC582ForSale
/NC582ForSale.htm
This D17S is for sale in Australia:
http://www.staggerwingforsale.com/
And you are sure to find more.
For reasons that might have had to do with military service, I have never
seen a Staggerwing that wasn't either bright yellow, or bright orange-red,
like a Ferrari.
Regards,
Dave Shugarts
On 3/19/08 9:11 PM, "nliner" <[EMAIL PROTECTED]> wrote:
> Since we are over to airplanes, does anyone know where a Beech GB-2 may
> be found.
> My father-in-law owned one the the past and is wondering where it might
> have gotten off to.
> Did not if Dave S. was familiar with this model.
>
> David Shugarts wrote:
>> Hi, Dave--
>>
>> Now it's getting interesting. I just wish we had a boat designer to chime in
>> here, as we are way over on the aviation side of this thing, I think.
>>
>> As an aviation editor for about 15 years, I got to hop into a lot of
>> aircraft, including the 177RG, which I liked a lot. Our company plane was an
>> M20J and I also did aerobatic training in an 8KCAB, which has the
>> "semi-symmetric" wing airfoil because they figured you'd want to be inverted
>> a lot. (There's one of those still missing, with Steve Fossett in it.)
>>
>> Regards,
>>
>> Dave S. (II)
>>
>>
>> On 3/17/08 2:32 PM, "David Shaddock" <[EMAIL PROTECTED]> wrote:
>>
>>
>>> Hi, other Dave S.--
>>> Your hunch is correct; laminar flow in water disappears at a pretty low for
>>> the waterline lengths and foil lengths we're discussing. After I wrote my
>>> comments earlier, I went back through the thread and found the link to Bryon
>>> Anderson's excellent article, which explained everything I was trying to
>>> cover in a better fashion, with diagrams too. He mentions 5 knots as the
>>> approximate speed at which we lose laminar flow. That's oversimplifying,
>>> but it gives you an idea. But laminar flow has a lot to do with the NACA
>>> profile--some profiles intentionally move the maximum depth aft in order to
>>> maximize laminar flow; the idea is to keep the lift working for you as long
>>> as possible. My last plane was a Cessna 177RG, which had a laminar flow
>>> wing designed to keep the flow 'attached' for 70% of its surface or better
>>> at speeds of about 170 mph. It took a long time getting off the ground, but
>>> was incredibly efficient in the air. It was very different from my friend's
>>> 175 (we traded for a while so he could get his commercial license), which
>>> had a fat high-lift wing that got you off the runway in a third of the
>>> distance but only provided 2/3 the top speed for the same power and fuel
>>> burn.
>>>
>>> Just because a flow goes turbulent, we're still interested in it and it can
>>> still perform some useful work. Besides, it's kind of a necessary evil; you
>>> can't just provide the part of the foil that gives you laminar flow and then
>>> remove the rest <grin>. The whole profile works together.
>>>
>>> Now, you mentioned vortex generators... They sell dimpled surface material
>>> for airplanes to put on the surfaces where the flow starts to detach, under
>>> the theory that the dimples (like the ones on golf balls, except standing
>>> proud of the surface) generate mini-vortices that help keep the flow (albeit
>>> turbulent) attached. Makes me wonder what this would do on the aft faces of
>>> a keel. I notice my BMW has raised bumps all over the edges and strut for
>>> the side-view mirrors, to cut wind noise by keeping the flow attached so it
>>> can't escape and whistle.
>>>
>>> But let's talk for a minute about porpoises. Capable of 25 knots
>>> underwater, and without a turbulent boundary layer... I guess they don't
>>> understand Reynolds numbers. Apparently they have a paper-thin outer skin
>>> with a thin spongy layer below that covering their real skin. One theory
>>> says they can detect turbulence and adjust their body shape to reduce it by
>>> controlling this soft layer. Dr. Kenneth Davidson studied them heavily and
>>> figured their speed was more due to their streamlined shape and the smooth,
>>> oily skin, but later research does suggest that the softness is apparently
>>> as important as the skin. But I wonder why my inflatable isn't quicker...
>>> Anyway, since I don't see a mechanism for the porpoises to control this fat
>>> layer, maybe it's a passive thing. I don't think I'm ready to plaster my
>>> keel with neoprene to try it out, but it makes me wonder if the flexible
>>> layer couldn't react to impending turbulence and change shape just enough to
>>> keep the flow attached.
>>>
>>> Dave Shaddock
>>>
>>> -----Original Message-----
>>> From: [email protected]
>>> [mailto:[EMAIL PROTECTED] On Behalf Of David Shugarts
>>> Sent: Monday, March 17, 2008 12:14 PM
>>> To: [email protected]
>>> Subject: Re: catalina27-talk: Keel Fairing
>>>
>>>
>>>
>>>
>>>
>>> Hi, Dave--
>>>
>>> That's all true, more or less, but what I have a strong hunch you will find
>>> is that these foils do not give us laminar flow at our speeds and angles of
>>> attack.
>>>
>>> In other words, going to windward, I believe you would find that we are
>>> nearly always in some form of turbulent flow, at some point in the keel
>>> section, unlike aircraft, where we do get laminar flow most of the time,
>>> over most of the wing.
>>>
>>> (BTW, the ratio of Reynolds numbers is 13:1, water versus air. Don't hold me
>>> to it, but I believe this is the practical consideration when modeling
>>> foils.)
>>>
>>> These days, there are inexpensive underwater cameras that could perhaps show
>>> us what our keels are doing. It isn't a fair comparison, but I get a good
>>> look at my rudder and it always looks like it's in some degree of turbulent
>>> flow going to windward. (I have the old rudder, which is an anachronism.)
>>>
>>> Regards,
>>>
>>> Dave S.
>>>
>>> PS-I am very familiar with the root versus tip design concept for beneficial
>>> stall behavior in aircraft, and we could throw in wing twist if we wanted to
>>> complete the picture. And let's not even get started with Whitcomb winglets,
>>> stall fences and stall strips, not to mention vortex generators.
>>>
>>>
>>> On 3/17/08 12:31 PM, "David Shaddock" <[EMAIL PROTECTED]> wrote:
>>>
>>>
>>>> The Cessnas and other aircraft sometimes use different foil shapes at the
>>>> root and tip in order to make sure the inner part of the wing (closer to
>>>>
>>> the
>>>
>>>> fuselage) stalls first, making the aircraft dive and regain speed while
>>>> still providing some control out at the wingtips to avoid a spin. This
>>>> isn't an issue with sailboats.
>>>>
>>>> But our keels can still stall--the keel provides windward lift if it
>>>>
>>> doesn't
>>>
>>>> stall, at the expense of some leeward slip. If the keel stalls, you lose
>>>> the lift and you see a lot more leeward slip/skidding.
>>>>
>>>> There are so many NACA profiles that it's hard to imagine anyone using
>>>> something that's NOT a NACA profile--they have tested and published
>>>>
>>> results
>>>
>>>> for hundreds of them, with some having only a tiny variation from others.
>>>> But those tiny variations can make measurable differences, especially
>>>>
>>> since
>>>
>>>> we're operating our profile in a medium 800 times denser than air. I have
>>>>
>>> a
>>>
>>>> book I used for aircraft design purposes that's got everything they had
>>>> published through about 1990. At any rate, selection of the ideal profile
>>>> for a sailboat involves knowing the aspect ratio as well as the target
>>>> speeds. For example, there is a concept called the lift/drag bucket--a
>>>> high-lift keel profile provides a lot of drag, but might be a worthwhile
>>>> price to pay if you're trying to achieve the best VMG in light air,
>>>>
>>> because
>>>
>>>> at low speeds the drag doesn't hurt as much and adding lift while
>>>>
>>> minimizing
>>>
>>>> leeward slippage pays off. For higher speeds, a lower-lift profile works
>>>> better because when the boat is moving faster through the water, you'll
>>>>
>>> get
>>>
>>>> a resultant increase in the actual lift windward and have less drag to
>>>>
>>> worry
>>>
>>>> about--but overall you'll see more leeward slippage.
>>>>
>>>> A bulb at the bottom of the keel offers two things--for one thing, it
>>>> minimizes the tip vortex (which adds a great deal to drag), but mainly it
>>>> helps provide a lot of mass at the extreme draft, which provides more
>>>> righting moment. If the rules allow, you can carry more sail because of
>>>>
>>> the
>>>
>>>> extra righting, and you'll heel less which means more sail upright and
>>>> working for you (although heeling may increase your waterline length on
>>>>
>>> some
>>>
>>>> hulls and raise your speed). If the rules don't allow added sail, you can
>>>> take advantage of the increased righting moment by cutting weight out in
>>>> other areas and you'll accelerate faster.
>>>>
>>>> The profile Tim has picked out for his sportboat is a good one; at the
>>>> speeds he might be getting on a planning boat, he could probably have done
>>>> well with a narrower profile, too, but this way he's covered for a wide
>>>> range of conditions.
>>>>
>>>> A lot of this information is in Steve Killing's book on Yacht Design and
>>>> also in Skene's Elements of Yacht Design--but the later publications of
>>>>
>>> that
>>>
>>>> are much more informed than the early ones).
>>>>
>>>> Dave Shaddock
>>>>
>>>> -----Original Message-----
>>>> From: [email protected]
>>>> [mailto:[EMAIL PROTECTED] On Behalf Of David Shugarts
>>>> Sent: Monday, March 17, 2008 10:52 AM
>>>> To: [email protected]
>>>> Subject: Re: catalina27-talk: Keel Fairing
>>>>
>>>>
>>>>
>>>>
>>>> Hi, Tim--
>>>>
>>>> I think your summation of it as "like a Chevy" is a pretty good analogy.
>>>>
>>> To
>>>
>>>> go back to the source, I have now heard Frank Butler answer a number of
>>>> sophisticated questions with what sure sounded like naivete to me, so I
>>>>
>>> have
>>>
>>>> a hunch that our factory keel section was a "oh, whatever" decision at the
>>>> time. Then these better keel sections would naturally be an improvement,
>>>>
>>> but
>>>
>>>> only because the bar was set so low.
>>>>
>>>> It would be interesting to hear from an expert here, because I just feel
>>>>
>>> as
>>>
>>>> though the designers of the cool toys are way beyond NACA foils. Or
>>>>
>>> perhaps
>>>
>>>> they really are more about the bulb than the keel section itself. For
>>>> instance, if we could hang a heavy lead bulb on a carbon fiber keel, we
>>>> would probably do it, and we might find that ANY keel foil would be fine
>>>>
>>> for
>>>
>>>> the purpose.
>>>>
>>>> BTW, this link: http://www.hanleyinnovations.com/glossary.html, shows a
>>>>
>>> few
>>>
>>>> cases where the NACA 0012 was used in aircraft, but it also shows that
>>>>
>>> some
>>>
>>>> venerable aircraft (e.g., the Cessna 150/152) had one foil at the wing
>>>>
>>> root
>>>
>>>> and another at the tip (in other words, more sophisticated). Notably, the
>>>> B-17 Flying Fortress had it as the root foil (love that airplane!).
>>>>
>>>> Regards,
>>>>
>>>> Dave S.
>>>>
>>>>
>>>>
>>>>
>>>> On 3/17/08 12:03 AM, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote:
>>>>
>>>>
>>>>> I don't profess to have any knowledge whatsoever when it comes to fluid
>>>>> dynamics, I have just been going on threads on SA and bits and pieces of
>>>>> knowledge that I've read from different designers.
>>>>>
>>>>> I think that as far as high performance (e.g., sport boats, hulls that
>>>>> will plane
>>>>> off the wind) sailboats are concerned, a bulb on a keel foil is pretty
>>>>> much the
>>>>> name of the game. Certainly heavy displacement and cruising boats will
>>>>> look toward other keel configurations. But the NACA foils offsets have
>>>>>
>>>> pretty
>>>>
>>>>> much been determined to be the go-to configurations for fast keel struts
>>>>> in the sportboat world. There are a few arguments over whether a 0011
>>>>>
>>>> section
>>>>
>>>>> might be faster than a 0012 seciton (with a resulting decrease in
>>>>> strength/robustness
>>>>> to loads, etc) for example, but the 0012 shape seems to be the chevy
>>>>> pickup when
>>>>> it comes to most foil sections below the waterline.
>>>>>
>>>>> These are fairly simple shapes. Pretty easy for an amateur to cut with a
>>>>> hot wire,
>>>>> or for a CNC machine to do it.
>>>>>
>>>> (http://www.youtube.com/watch?v=q7uvq4RlhHM)
>>>>
>>>>> I can certainly imagine that areonautical designers would have the need
>>>>>
>>> to
>>>
>>>>> come up
>>>>> with more complex shapes for specialized, shape-specific demands,
>>>>>
>>> executed
>>>
>>>>> at high speed with enormous G-force loads in the atmosphere, and new
>>>>> materials and production techniques would allow for a huge amount of
>>>>> variability when it comes to foil offsets these days.
>>>>>
>>>>> But these are just simple symmetrical foils shapes that you can order up
>>>>> and get made pretty cheaply on-line...I just ordered a 54" piece of
>>>>> spyderfoam cut to NACA0012 sections,
>>>>> for about a hundred bux incl. delivery. It's a dream-world out there now
>>>>> for home boat (or aircraft) builders!
>>>>>
>>>>> tf
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> My ears perk up here. First, I confess ignorance. Are boat keels based
>>>>>>
>>> on
>>>
>>>>>> NACA foils, and do they apply to water, as opposed to air? Perhaps there
>>>>>> was
>>>>>> a series of NACA foils intended for water? I just never paid attention
>>>>>>
>>> to
>>>
>>>>>> that part of things, although I studied NACA airfoils for my own
>>>>>>
>>> purposes
>>>
>>>>>> many years ago. I vaguely recall a factor called Reynolds Number that
>>>>>> would
>>>>>> govern foils in various media, such as air and water. Can you elaborate?
>>>>>>
>>>>>> Regards,
>>>>>>
>>>>>> Dave S.
>>>>>>
>>>>>> PS--I was just a layman studying the foils at the time, but I went
>>>>>>
>>>> through
>>>>
>>>>>> them all pretty carefully. It seemed to me that they were kind of
>>>>>>
>>>> empircal
>>>>
>>>>>> in nature. I got the impression that the great virtue of a NACA foil,
>>>>>>
>>> for
>>>
>>>>>> an
>>>>>> aircraft designer of the 1930s or 1940s, was that it was thoroughly
>>>>>>
>>>> tested
>>>>
>>>>>> and predictable. However, it seemed as though a lot of developments of
>>>>>> later
>>>>>> decades, such as the Clark-Y, not to mention variable sweeps and tapers,
>>>>>> variable chords and foils in a given wing, etc., began to favor
>>>>>>
>>>> departures
>>>>
>>>>>> from the NACA foils (except when mere predictability was the goal, as in
>>>>>> vertical stabilizer foils). So, although I later got into aviation
>>>>>>
>>>> writing
>>>>
>>>>>> and was constantly looking for NACA foils, I didn't find many in the
>>>>>>
>>>> wings
>>>>
>>>>>> of light aircraft. In my time, we saw NASA come out with the GAW-1, and
>>>>>>
>>> I
>>>
>>>>>> have always assumed that later, composite aircraft designers were free
>>>>>>
>>> to
>>>
>>>>>> work with an infinitely variable foil in mind.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 3/16/08 8:40 PM, "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote:
>>>>>>
>>>>>>
>>>>>>>>>> but they also value every advantage they can get.
>>>>>>>>>>
>>>>>>> key words^, huh?
>>>>>>>
>>>>>>> nice explanation, Chris.
>>>>>>>
>>>>>>> So I guess Compu-Keel is still around?
>>>>>>>
>>>>>>> http://www.compukeel.com/
>>>>>>>
>>>>>>> odd because you get NACA foil specs on-line for free...but I guess all
>>>>>>> class
>>>>>>> legal keels cant be derived from NACA sections.
>>>>>>>
>>>>>>> tf
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>
>>
>>
>>
>>
>>
