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  1. Jul 23, 2010 #1

    stikmunkey

    stikmunkey

    stikmunkey

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    Hi all,

    I'm looking to redesign the BD-5B a little bit, mainly the wing and build myself a composite version. I only have a 3-view of the BD-5J version.

    Does anyone know which part of the fuselage was stretched as well as changes to the wings and stabilizer?

    Does anyone have a drawing of the 5B?

    Thanks
    Ryan
     
  2. Jul 23, 2010 #2

    orion

    orion

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    I believe the fuselage of the BD-5 stayed consistent between the "A" and "B" models - the only modifications made were for the incorporation of the jet engine.

    The only difference between the two was that the "B" model used a longer wing. I think the tail and the airfoil sections remained the same.

    I might have a 3d loft of the BD-5 in Rhino format.

    There were two attempts at developing a composite version of the BD-5 some years back. Both increased the overall size a bit (one was to be a two place) but I don't think either succeeded in getting it into the air.
     
  3. Jul 23, 2010 #3

    djschwartz

    djschwartz

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    The first attempt at the design by Jim Bede was to be a composite airplane, at least the fuselage. I can still recall the ads of him holding the composite fuselage shell with a heading like "Fly it today" or some such nonsense. The composite version never was completed and he then switched to all aluminum for the "production" kits. I don't know the reason why, it was too long ago and Bede was never honest or forthcoming about anything he was doing.
     
  4. Jul 23, 2010 #4

    Hot Wings

    Hot Wings

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    The stretch was done behind the FU-1 bulkhead just behind the pilot and was to allow for larger and heavier engines.

    Orion is correct that the only difference between the A and B wing was span. They even used the same ribs. The fuselage parts are identical, at least in the 2 kits I have.

    It is my understanding that the jets used a 17 ft long "G" wing with a different airfoil. I believe that even though there were some modifications of the airframe for the jet version the external dimensions remained unchanged.

    I quit building my -5's due to not finding an engine I liked. Even though it has a bad reputation it seems that those that have actually flown one say it's a nice plane to fly.

    But if you screw up there is zero in the way of pilot protection.

    Plans should still be available from the 2 normal BD-5 sources.
     
  5. Jul 23, 2010 #5

    Hot Wings

    Hot Wings

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    The first ones were built using angle aluminum structure similar to the BD-4 and covered with a fiberglass skin. I'd have to refresh my knowledge of the facts but I think that the prototype with the "V" tail actually flew. It's still hanging around at the EAA museum, I think?


    The stated reason for switching to the aluminum version was to make volume production practical, and is believable. He had plenty of orders to justify the change. I suspect quality control had something to do with the decision as well since he said he planned to get the thing certified.

    But we stray from the OP's intent of this thread, on a rather emotional subject.
     
  6. Jul 23, 2010 #6

    orion

    orion

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    Actually the history goes a bit further back: The BD-5 was actually initiated, designed and developed first by Jim Bede's father who at the time worked for one of the European glider factories (don't recall which one but like the BD-5 it too was all aluminum). If you look at the nose you'll see that it is the glider's shape and structure, to the point of even using many of the glider's production parts.

    The project and kit was eventually taken over by JB, who of course took credit for the development (if I recall right, his father was not interested in the kit business but I don't recall the details).

    The fiberglass version came later but was dropped for unknown reasons (at least unknown to me).
     
  7. Jul 23, 2010 #7

    orion

    orion

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    A bit more on the fiberglass - it was presented as an early follow-on prototype and it was the one with the "V" tail, which proved less than adequate for the small plane (did fly though). It was at that point where BD hired Burt Rutan to fix the design - out of that association came the BD-5 we see today. As far as why the composite went out of favor is concerned, it was apparently two factors that led to the cessation of its use - first, they had all the tools for the production of the aluminum parts so the composite production would have presented an extra expense. And also, the composite was heavier than the aluminum configuration and since the plane is very sensitive to the extra pounds, the composite idea was scrapped.
     
  8. Jul 24, 2010 #8

    kent Ashton

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    I own a BD-5 on the gear and have given some thought to this before. Forget the idea. Build a design with a proven record of completions. I can give several reasons but I'll stick to the wing: Composites are heavier than aluminum, you must join your fiberglass wing spar (usually a boxy shape) to a round aluminum tube center-spar with only about 6" of overlap that carries the entire flight load of the airplane. Fiberglass and aluminum have different expansion rates. The wing must be hollow to hold fuel so the upper skins are in compression with no core support as in the Rutan designs. Fiberglass in weak in compression therefore the upper wingskins will flex unless the wing spar is made very stiff (and heavy) or you stiffen them with a sandwich.

    A couple of fellows have started out to build composite BD-5s. There is a fellow selling molded fuselage shells even now. None of them has flown, to my knowledge. If you really want a BD-5, build it per the plans. At least then you have a chance of getting it done.

    OTOH, what the hell, it would be fun to work on. Send me plans when you're done. :)
     
  9. Jul 24, 2010 #9

    flyvulcan

    flyvulcan

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    There is a set of molds for a composite BD5 on Juan Jiminez's BD5 website For Sale BD-5 Web Site. The advertiser is offering to build composite parts. I believe the molds themselves were for sale a while back. Maybe they've been sold and the new buyer is now producing parts or maybe the seller couldn't sell them so is now trying to recoup some of his investment...

    Along with the Bede Micro and Alturair websites, Juans is probably the most informative BD5 website around.

    Dave
     
  10. Jul 24, 2010 #10

    Inverted Vantage

    Inverted Vantage

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    So I've seen it mentioned in this thread that the BD-5 was dangerous in a crash as it had no protection for the pilot...I would think that this would be the case for almost all aircraft of the BD-5's size. Is this incorrect? What about the design makes it so bad?
     
  11. Jul 24, 2010 #11

    TFF

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    Hitting the ground.
     
  12. Jul 24, 2010 #12

    Hot Wings

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    I've been interested in the -5 for many years, bought a couple of kits and was actively building till I got to the engine impasse. I have never flown a BD-5. I have over the years read everything I could about the plane and tried to sort out the emotionalism from the facts.

    In my opinion the design isn't bad. (other than WAY too many little pieces to make) As I noted above those that have actually flown it say it flies very well.

    My current project, which I purchased with the intent of finishing quickly to have a trainer with take off and landing performance similar to the BD-5, has a much better reputation.

    The difference in the 2? My current project has had a higher percentage of completed planes crash, and for reasons directly related to the design and performance. But the injury rate has been rather insignificant.

    The BD-5 on the other hand has a better safety record when you toss out pilot error. But because there is very little crush structure forward of the pilot and the engine is behind you, shielded by nothing more than an 032" aluminum bulkhead, if you hit anything, it's going to hurt.

    So why am I building a plane with known design and performance defects and not the BD-5? I'm getting a bit older and realize that I do actually make a mistake now an then :shock: and like the crash protection offered by my current project. There are proven fixes for it's deficiencies. It also happens to fit what I like to use an airplane for very well.

    Disclaimer: All of the above based on my observations and opinions only.
     
  13. Jul 24, 2010 #13

    wally

    wally

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    If I may add my $.02:

    I have never flown a BD-5. From what I have heard and read, yes it does fly fine - if you are comfortable flying a very small, high performance aircraft. It is a lot like a little fighter aircraft.

    It is not an airplane for the low time pilot with no high performance aircraft flying experience. Your mileage and experience may vary.

    I am just sayin'.
    Wally
     
  14. Jul 24, 2010 #14

    orion

    orion

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    A minor correction to an earlier post - it turns out that the BD-5 was stretched at one point about 5.5". Eventually that fuselage became the standard - I'm not sure when the stretch was done.
     
  15. Jul 25, 2010 #15

    Hot Wings

    Hot Wings

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    I don't think the stretch was done while the kit was still in production. I got my stretch kit from BD Micro and I think they originated the mod. I spent a good number of hours drilling rivets and scrubbing ProSeal off with MEK to put it on an already finished fuselage. Not sure I ever recovered from the MEK:lick:
     
  16. Jul 26, 2010 #16

    stikmunkey

    stikmunkey

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    Wow, I have't check the post in a few days and what great replies! Thanks everyone. ;)

    I am planning to redesign the fuselage a bit by lengthening it and also increase the width by a couple inches.

    Also plan to redesign the wing with new airfoil(s) and maybe incorporate wing tip washout if needed.

    Does anyone know why didn't the BD-5 wing have washout - was it because they were trying to keep the construction simple for the home builder? or was it some aerodynamic issue/disadvantage?
     
  17. Jul 26, 2010 #17

    stikmunkey

    stikmunkey

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    Do you have the loft still and can I have it. It would save me a lot of time in front of the computer. I use Solidwork but should be able to import OK.
     
  18. Jul 26, 2010 #18

    stikmunkey

    stikmunkey

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    I think that once I get the 3D model going I should be able to calculate the weight of the composite and have a pretty good idea but I don't plan to build the plane out of glass. It will be mostly carbon fibre sandwich construction.
     
  19. Jul 26, 2010 #19

    orion

    orion

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    Here's a small Rhino loft of the BD-5. I'm not sure how accurate it is since it was developed off of relatively insufficient drawings, but it should be in the ballpark.
     

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  20. Mar 22, 2019 #20

    Saville

    Saville

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    How difficult would it be to modify a BD-5B fuselage to accept the jet engine?

    I'm sure a lot depends upon how far along the fuselage is so let's say you have an untouched BD-5B prop driven kit and you want to modify it to use the jet.

    Thanks
     

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