Ok, what about the BD5

"Morgans" wrote in message
...

"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.

No BD-5 has suffered an inflight failure involving either the airframe or
the drive train hardware.

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.

My web site includes a library of material that includes things like this.
Help yourself, that's why I put it there, the good _and_ the bad.



--
Posted via a free Usenet account from http://www.teranews.com

"J.Kahn" wrote in message
...
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.

Actually, both of these statements are incorrect.

These two pictures show what's left of a Canadian BD-5 that landed in a
raspberry patch and essentially tore itself apart.

http://www.bd5.com/Canada/Canada01.jpg
http://www.bd5.com/Canada/Canada02.jpg

The man holding the pieces is the builder and pilot. He walked away. About
30% of accidents involving BD-5's are fatal. 23% of RV-6 accidents have been
fatal, and that's not counting the fact that some of those accidents had
more than one victim. You can verify that yourself on the NTSB web site.

The Microturbo TRS-18 that is most commonly used on the BD-5J is a very
finicky engine in many respects. For example, any minor deviation on fuel
pressure can cause the engine to shut down. The fuel pumps are very critical
components, which is why at least one of the operators is heavily involved
in designing replacement components and reengineering a portion of the fuel
system to increase reliability in this area. The irony is that even though
BD-5J's are mostly used for homeland security as cruise missile surrogates,
Microturbo, with facilities in Grand Prairie, TX, refuses to cooperate. They
won't even sell parts, directly or through the military.




--
Posted via a free Usenet account from http://www.teranews.com

I thought so too. It turns out the engine is too wide and too heavy, and the
fact it is watercooled adds even more complexity. So far, I haven't seen a
single BD-5 built with a 912.

"wesley maceaux" wrote in message
...
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.








--
Posted via a free Usenet account from http://www.teranews.com

On 1/4/2007 12:37:26 PM, "J.Kahn" wrote:
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


Yeah, that's another thing that I'm sure escaped most of the early buyers.
Even with the later wing modifications, for such a small airplane, it has
some really considerable runway requirements. William The Conqueror would
have probably needed to go with floats.



--
Whome?

"wesley maceaux" wrote in message
...
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.

My father had a friend that owned one and he loved it. I'm not sure what
powerplant he used, but the fact that he probably didn't weigh over 160lbs,
was an Air Force pilot, and built light - probably helped the cause.

I think a lot of Cessna 150/172 guys found more they could handle in the
BD-5, especially after losing an engine. I think if more BD-5 pilots were
less concerned about getting back to the airport after an engine failure and
more concerned with maintaining airspeed, we'd have a few more BD-5 pilots.

Do the stats back that up in any way?

That said, designing around an unproven engine is probably a bad place to
start. Designing around an engine that hasn't been produced, probably a
bigger problem. I forget the details. What did the prototypes fly with?

"Juan Jimenez" wrote in message
...

"Morgans" wrote in message
...

"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.

No BD-5 has suffered an inflight failure involving either the airframe or
the drive train hardware.

Correct, but that statement avoids the issue. There are/were unsolved
torsional problems. During the so-called development period for the design
they fought a number of problems including broken drive shafts, broken
engine mounts, etc. which were results of various torsional issues which
were never completely resolved.

http://www.prime-mover.org/Engines/T.../contact1.html

The only reason there were no in-flight failures of drivetrain hardware is
that the people involved with the design, both the Bede team and tinkerers
over the last 30 years have been dilligent and lucky enough to identify
failures and pending failures on the ground, rather than discovering the
failures in the very rarely demonstrated airborne mode of the design.



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.

My web site includes a library of material that includes things like this.
Help yourself, that's why I put it there, the good _and_ the bad.


--
Posted via a free Usenet account from http://www.teranews.com

Morgans wrote:



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.
--
Since the BD5 only has one seat, it is not possible to be trained in
type. I can't think of a common training aircraft that even comes
close. It was supposed to be affordable for anyone, even those who did
not have a lot of high performance experience, yet it has a high stall
speed and a 'responsive' feel. This just sounds dangerous.

Has there ever been a single seat, low cost high performance aircraft
that has been successful? I won't count the Mini 500:-)

John Halpenny

It was the plane that we all wanted the moment we first saw it. We
were young and probably a bit foolish. Utility wasn't of interest,
speed and flying were the defining elements. The BD5 was the answer
and the price promised to be right. Times have changed and most of us
have matured and moved on to bigger and better goals. The market has
also matured and people expect more from their aircraft.

Richard Riley wrote:
On Thu, 04 Jan 2007 13:37:27 -0500, "J.Kahn"
wrote:


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.

It started off with a big disadvantage - single place, no room for
luggage. Any safety or reliability, or business issues aside, the
configuration is simply not *practical.*

Sure, it's fun, it's sexy, it's a wannabe fighter pilot's daydream.
But exactly HOW are you going to have fun with it?

Since it's one seat, you can't take your friends up and impress them.
You can't take your Significant Other out for a $100 hamburger. No
luggage, so you can't use it for a business trip.

Mostly, you go up, fly around, and land back at your home airport.

If that's your mission, the high speed is not a good thing. It just
increases the pilot work load. It's not aerobatic, it's not a good
instrument platform, so you're not going to use it to practice your
pilot skilz. It's utility is very limited, it's practical mission
(go up and have some fun and come back down) is better served by just
about anything else that flies.

The only real things it had going for it (from a sales point of view)
were great looks and responsive controls.

So your market is someone with high risk tolerance, willing to tinker
a lot, doesn't want to take a passenger or baggage, who wants to fly
fast but not actually go anyplace. That's a VERY limited market.

I lost a LOT of customers just because I was selling a plane with 2
seats in tandem. Their wives/girlfriends didn't want to sit in back.
It was side by side or nothing.

From a configuration/mission/market standpoint, the BD-12 made a lot
more sense. Too bad it didn't fly.

Juan Jimenez wrote:

"J.Kahn" wrote in message
...
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.

Actually, both of these statements are incorrect.

These two pictures show what's left of a Canadian BD-5 that landed in a
raspberry patch and essentially tore itself apart.

http://www.bd5.com/Canada/Canada01.jpg
http://www.bd5.com/Canada/Canada02.jpg

The man holding the pieces is the builder and pilot. He walked away. About
30% of accidents involving BD-5's are fatal. 23% of RV-6 accidents have been
fatal, and that's not counting the fact that some of those accidents had
more than one victim. You can verify that yourself on the NTSB web site.

The Microturbo TRS-18 that is most commonly used on the BD-5J is a very
finicky engine in many respects. For example, any minor deviation on fuel
pressure can cause the engine to shut down. The fuel pumps are very critical
components, which is why at least one of the operators is heavily involved
in designing replacement components and reengineering a portion of the fuel
system to increase reliability in this area. The irony is that even though
BD-5J's are mostly used for homeland security as cruise missile surrogates,
Microturbo, with facilities in Grand Prairie, TX, refuses to cooperate. They
won't even sell parts, directly or through the military.





I see your point Juan, although I could probably spin that around and
say it has a "76% higher fatality rate than an RV-6!"

Obviously you're dead as a doornail in a stall spin accident in either
airplane. What would be interesting to see is the survival rate of BD-5
vs other homebuilts in a controlled forced landing, which when you get
down to it is the key issue that I would worry about.

I would think the ideal engine would be a properly developed wankel.

John

On Thu, 4 Jan 2007 10:50:29 -0600, "Whome?" wrote:

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

Dave "Hammer" Harris, an airshow pilot who used to fly a BD-5J at airshows, is a
member of one of my EAA Chapters. He likes the -5 a lot, though he says there's
a lot of things you have to correct if you start with a Bede kit. He had the
jet for the shows, and a VW-powered version for his personal bird. Used to fly
it to Chapter events. Went by his hangar once, and he had a third,
partially-completed model, too.

Don't know if he's still flying any of them. I know he had an engine fire with
his VW a number of years back.

Ron Wanttaja