Ok, what about the BD5

Ok, we have roasted the Mini 500, how about the BD5?

First things first, forget the jet. So few people could ever afford such a
thing it hardly seems viable from the get-go. But why has such a popular
design (on paper) found so little success? Thousands of people instantly fell
in love with it immediatley when it was introduced in what, the late 1060s.
So after 45 years or so, and so many parts floating around, what has so
greatly hampered this little birds sucess?

Looking back with my limited aviation experience, and yes I was there. I
visited Newton Kansas in the early 70s, met Jim Bede, and sat in one of the
completed prototypes in the show room floor. But the only thing that seems
apparent to my inexperience is the lack of a reliable piston power plant, due
to weight and power restrictions - and it's a VERY high performance aircraft,
that was gobbled up by a lot of low performance pilots.

Some time around 1980 or so, I saw and airshow demonstration by the Coor's
Silver Bullet, and the craft performed some amazing manuvers. So will this
airframe fly well if properly powered? Is there any way to make one a
workable craft if a pilot is qualified for such a high performance ship?

Let's see how many people can respond with a fair discussion, and ignore
Juan's bias of coarse, and examine the real reason this bird has never
soared.

--
Whome?

Probably lots of different reasons why it has not achieved the flying
success it should have but you hit on the biggest and probably most
important, no suitable engine. Yeah, I know that there are now many
good engines that could power it well but its time was then and this is
now. It was ahead of its time then and the needed engine wasn't
available. Now, its time has passed and few people are really
interested a plane with such demanding characteristics and limited
usefulness.

Yes, I was one of the many that fell in love with the BD5 the very
first time I saw it. It was then and remains a beautiful design that
seems to scream "FLY ME". It will fly well if properly powered, of
that there is no argument. I also believe there is little argument and
ample historical evidence to show that it is a high performance
aircraft with little room for error on the pilots part.

Ultimately though, I think the biggest reason it has not rebounded over
the years was Van's RV-4, RV-6, RV-7, RV-8 and RV-9 aircraft. Those
aircraft were slightly bigger, appealed to more pilots, were easier to
build, used proven available engines, offered performance galore and
were far easier for the average pilot to fly. They have literally
pushed most other kit manufacturers into the also-ran category. When
Bede first offered the BD5 as a KIT, it was a rather new concept.
Previous designs were just that, designs and you had to build them from
scratch. The idea of buying kits and assembling the parts to produce
your own plane appealed to a lot of people then and still does today.
Van's has taken that concept well beyond its origin of just a boxs full
of cut sheet metal and delivered on a true assembly kit. That was the
promise that the BD5 never really delivered.



Whome? wrote:
Ok, we have roasted the Mini 500, how about the BD5?

First things first, forget the jet. So few people could ever afford such a
thing it hardly seems viable from the get-go. But why has such a popular
design (on paper) found so little success? Thousands of people instantly fell
in love with it immediatley when it was introduced in what, the late 1060s.
So after 45 years or so, and so many parts floating around, what has so
greatly hampered this little birds sucess?

Looking back with my limited aviation experience, and yes I was there. I
visited Newton Kansas in the early 70s, met Jim Bede, and sat in one of the
completed prototypes in the show room floor. But the only thing that seems
apparent to my inexperience is the lack of a reliable piston power plant, due
to weight and power restrictions - and it's a VERY high performance aircraft,
that was gobbled up by a lot of low performance pilots.

Some time around 1980 or so, I saw and airshow demonstration by the Coor's
Silver Bullet, and the craft performed some amazing manuvers. So will this
airframe fly well if properly powered? Is there any way to make one a
workable craft if a pilot is qualified for such a high performance ship?

Let's see how many people can respond with a fair discussion, and ignore
Juan's bias of coarse, and examine the real reason this bird has never
soared.

--
Whome?

Whome? wrote:
Thousands of people instantly fell
in love with it immediately when it was introduced in what, the late 1060s.


Yeah I heard that William The Conqueror put down a deposit right after
invading England and was screwed by Bede in 1069...

Just teasing; that sort of typo is just too tempting...

Bottom line is the airplane, while a brilliant design, has always
suffered for lack of a really reliable powerplant that was light enough.
The lack of crashworthiness inherent in the BD 5's configuration makes
engine reliability really critical. In the end the jet version is
probably the safest one due to the better reliability of a turbojet.

Add in the fact of size, the nasty stall behavior with an 80mph stall
speed with the original 64-212 root airfoil (!) (see:
http://www.bd5.com/reprofile.htm ). Even with the reprofiled airfoil the
stall is still 60 which means you touch down at 70 and you really don't
want to do that in a plowed field after the belt on your Honda lets go.

So, you have an airplane with a market limited to those with high risk
tolerance and at the same time willing to do a lot of tinkering, which
is pretty small.

For someone that really wanted that configuration, the Mini Imp was
probably a more practical choice.

John

It is interesting that we often look at a design approvingly, only to talk
about the lack of a suitable powerplant.

I find this perverse, as it acts like the powerplant isn't part of the
design.

"BobR" wrote

Probably lots of different reasons why it has not achieved the flying
success it should have but you hit on the biggest and probably most
important, no suitable engine. Yeah, I know that there are now many
good engines that could power it well but its time was then and this is
now. It was ahead of its time then and the needed engine wasn't
available.

I don't think that is quite true. There may be better engines now, but that
is only part of the problem with the piston engine in the BD-5.

The link escapes me now, but there were tremendous problems with torsional
harmonics, tearing apart everything, all the way along the drive train.

Beef up the driveshaft, and the clutch tore apart. Fix the clutch, and the
engine mounts cracked, beef them up, and something else broke. So on, and
so on.

Anyone happen to have the links handy that addressed all of these issues?
It was a very interesting read, although a lot of material. I think they
would answer, with great detail, why the 5 never caught on. They self
destructed.

Van's RV-4, RV-6, RV-7, RV-8 and RV-9 aircraft. Those
aircraft were slightly bigger, appealed to more pilots, were easier to
build, used proven available engines, offered performance galore and
were far easier for the average pilot to fly.

Although I have never flown one, the experienced pilots that did said things
like; it would eat most people alive, that it scared them, and so on.
--
Jim in NC

It's a good looking little plane..The rotax 912uls should give this plane a
real boost in performance .Always wanted one but the stall speed was way too
high for me.A stall of 40knts would be great but no dice.
"anon" wrote in message
m...
It is interesting that we often look at a design approvingly, only to talk
about the lack of a suitable powerplant.

I find this perverse, as it acts like the powerplant isn't part of the
design.

On 1/4/2007 3:21:53 PM, "Morgans" wrote:

"BobR" wrote

Probably lots of different reasons why it has not achieved the flying
success it should have but you hit on the biggest and probably most
important, no suitable engine. Yeah, I know that there are now many
good engines that could power it well but its time was then and this is
now. It was ahead of its time then and the needed engine wasn't
available.

I don't think that is quite true. There may be better engines now, but that
is only part of the problem with the piston engine in the BD-5.

The link escapes me now, but there were tremendous problems with torsional
harmonics, tearing apart everything, all the way along the drive train.

Beef up the driveshaft, and the clutch tore apart. Fix the clutch, and the
engine mounts cracked, beef them up, and something else broke. So on, and
so on.

Anyone happen to have the links handy that addressed all of these issues?
It was a very interesting read, although a lot of material. I think they
would answer, with great detail, why the 5 never caught on. They self
destructed.

Van's RV-4, RV-6, RV-7, RV-8 and RV-9 aircraft. Those
aircraft were slightly bigger, appealed to more pilots, were easier to
build, used proven available engines, offered performance galore and
were far easier for the average pilot to fly.

Although I have never flown one, the experienced pilots that did said things
like; it would eat most people alive, that it scared them, and so on.


Are you thinking about this one?
http://www.prime-mover.org/Engines/T.../contact1.html
I ran across it while doing a little research prior to this post.

I think all piston engine designs suffer too much from torsional vibration
problems. But most are just not serious enough to be destructive.

--
Whome?

Too many years ago to annouce publically, a friend of mine inquired with me
about sawing the gearbox off a Suzuki 750 Water-buffalo. For those of you
who are history impaired regarding two-stroke motorcycles, that engine came
from the GT750 and was a three cylinder two-stroke...or a two cylinder three
stroke...I don't remember

Anyway, with mild port work and a little boost in compression, the 750 would
probably put out 80 horsepower all day long, and Suzuki two strokes of that
time were known for being as reliable as a fire hydrant. The engine would
have weighed maybe 70-80 lbs, but required a water cooling system. And would
have been thirsty...

My friend had 900 hours in motor gliders at the time, I had maybe 20 in GA.
In retrospect, I'm glad the subject went away after a brief period of time.

Dale Alexander

"Whome?" wrote in message
...
On 1/4/2007 3:21:53 PM, "Morgans" wrote:

"BobR" wrote

Probably lots of different reasons why it has not achieved the flying
success it should have but you hit on the biggest and probably most
important, no suitable engine. Yeah, I know that there are now many
good engines that could power it well but its time was then and this is
now. It was ahead of its time then and the needed engine wasn't
available.

I don't think that is quite true. There may be better engines now, but
that
is only part of the problem with the piston engine in the BD-5.

The link escapes me now, but there were tremendous problems with torsional
harmonics, tearing apart everything, all the way along the drive train.

Beef up the driveshaft, and the clutch tore apart. Fix the clutch, and
the
engine mounts cracked, beef them up, and something else broke. So on, and
so on.

Anyone happen to have the links handy that addressed all of these issues?
It was a very interesting read, although a lot of material. I think they
would answer, with great detail, why the 5 never caught on. They self
destructed.

Van's RV-4, RV-6, RV-7, RV-8 and RV-9 aircraft. Those
aircraft were slightly bigger, appealed to more pilots, were easier to
build, used proven available engines, offered performance galore and
were far easier for the average pilot to fly.

Although I have never flown one, the experienced pilots that did said
things
like; it would eat most people alive, that it scared them, and so on.


Are you thinking about this one?
http://www.prime-mover.org/Engines/T.../contact1.html
I ran across it while doing a little research prior to this post.

I think all piston engine designs suffer too much from torsional vibration
problems. But most are just not serious enough to be destructive.

--
Whome?

Dale Alexander wrote:
Too many years ago to annouce publically, a friend of mine inquired with me
about sawing the gearbox off a Suzuki 750 Water-buffalo. For those of you
who are history impaired regarding two-stroke motorcycles, that engine came
from the GT750 and was a three cylinder two-stroke...or a two cylinder three
stroke...I don't remember


6 cylinder one stroke?

Dan, U.S. Air Force, retired

"Whome?" wrote in message
...
Ok, we have roasted the Mini 500, how about the BD5?

First things first, forget the jet. So few people could ever afford such a
thing it hardly seems viable from the get-go. But why has such a popular
design (on paper) found so little success? Thousands of people instantly
fell
in love with it immediatley when it was introduced in what, the late
1060s.
So after 45 years or so, and so many parts floating around, what has so
greatly hampered this little birds sucess?

Looking back with my limited aviation experience, and yes I was there. I
visited Newton Kansas in the early 70s, met Jim Bede, and sat in one of
the
completed prototypes in the show room floor. But the only thing that seems
apparent to my inexperience is the lack of a reliable piston power plant,
due
to weight and power restrictions - and it's a VERY high performance
aircraft,
that was gobbled up by a lot of low performance pilots.

Some time around 1980 or so, I saw and airshow demonstration by the Coor's
Silver Bullet, and the craft performed some amazing manuvers. So will this
airframe fly well if properly powered? Is there any way to make one a
workable craft if a pilot is qualified for such a high performance ship?

Let's see how many people can respond with a fair discussion, and ignore
Juan's bias of coarse, and examine the real reason this bird has never
soared.

You don't need to ask me. The easiest way to get an answer to your questions
is to ask the people who fly them on a regular basis. They all hang out on
the BD-5 mailing list on Yahoogroups, including some who worked at Bede
Aircraft Co. and some who have been flying the plane for 30 years, as well
as nearly 500 other BD-5 enthusiasts.



--
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