BD-5A/B factory engines study

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Rob de Bie

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Feb 7, 2021
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With the recent thread 'BD-5 - Why is it so engrained in our psyches?' running, I finished a small study on the BD-5A/B factory engines, and put it online. I always found the history of the factory engines confusing and vey difficult to understand. But with some effort the complete engine history (I think!) surfaced, and it included some small surprises too.

BD-5A/B factory engines

Comments are very welcome.

Rob
 

jlk69

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May 16, 2010
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Chula Vista, CA / USA
Cool little web page. The first three photos of the Xenoah engine were taken my by father Dennis Kunkel. The guy looking at the camera was my dad's friend and the other two people are unknown.BD-5 N503BD engine 7 rt. side S. Cal 70's.jpg
 

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jlk69

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Here are the remaining pictures of N503BD that I have from that air show appearance.
 

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  • BD-5 N503BD Prop S. Cal 70's.jpg
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Dantilla

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Aug 27, 2020
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BD Micro currently recommends a Hirth 3202 for a piston powered BD-5
 

Dantilla

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Aug 27, 2020
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Yes, but a different Hirth from the original.
Hirth has improved their product line.

Hirth went bankrupt right when Bede Corp was about to start shipping kits.
A mad scramble ensued to find an adequate replacement. That's why several different engines have been tried.
 

llemon

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Apr 29, 2021
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There is an interview series with Rutan where he talks a bit about the BD-5. 100% laminar flow was quite the objective!
 

Rob de Bie

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Feb 7, 2021
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Cool little web page. The first three photos of the Xenoah engine were taken my by father Dennis Kunkel. The guy looking at the camera was my dad's friend and the other two people are unknown.

Jon, thanks for responding! I traced back the webpage where I found the photos, and added source data to the photos.

I hope you don't mind me using them. The webpage initially was just a research page, not intended for publication. But when the thread 'BD-5 - Why is it so engrained in our psyches?' started, I could not resist sharing the findings. I tried finding the sources of all photos, but could trace back only half.

Rob
 

Rob de Bie

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Feb 7, 2021
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There is an interview series with Rutan where he talks a bit about the BD-5. 100% laminar flow was quite the objective!


Yeah, that one made me laugh out loud! Would it be possible to replicate that calculation? My first stumbling block is the surface area of the fuselage. Maybe someone has a 3D CAD model of the fuselage, that could give us that number?

Rob
 

GeeZee

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Feb 25, 2019
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Indianapolis, IN
Maybe you have already read this but its an article written by an engineer hired by Bede to solve the Torsional vibration issues he was having. I thought it was very interesting.
 

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raumzeit

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Mar 23, 2021
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Hirth 3202 with gearbox is about 100lbs.

That new Heron turboprop weighs 82 all-up.

And makes twice the power ~120hp.

I'd imagine a BD-5 with one sooner than later.
 
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Sometime in the remote past I think I remember reading that the -5's used to simulate cruise missiles were modified to hold as much as 50 gallons of fuel. Tanks were built into any free space they could find.

But then I also 'remembered' today that Penelope Purebred was the girl tied to the tracks in Rocky and Bullwinkle. It was Poly Purebred in Underdog.
Nell got tied to the tracks in R+B.
 

terke

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Dec 4, 2009
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Calgary, AB, Canada
Sometime in the remote past I think I remember reading that the -5's used to simulate cruise missiles were modified to hold as much as 50 gallons of fuel. Tanks were built into any free space they could find.

But then I also 'remembered' today that Penelope Purebred was the girl tied to the tracks in Rocky and Bullwinkle. It was Poly Purebred in Underdog.
Nell got tied to the tracks in R+B.
Yes I think that was Bobby Bishop’s company. They had a fleet of SMART-1 Jets. (Look that term up on YT)
They flew them pretty heavy, 1200 lbs from memory. They had a couple of crashes too.
Bobby sold his personal BD-5 to the Red Bull Flying Bulls. It did not take those guys long to crash his plane and kill the pilot. Sad.

Cheers,
Mark
 

jlk69

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May 16, 2010
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Location
Chula Vista, CA / USA
Jon, thanks for responding! I traced back the webpage where I found the photos, and added source data to the photos.

I hope you don't mind me using them. The webpage initially was just a research page, not intended for publication. But when the thread 'BD-5 - Why is it so engrained in our psyches?' started, I could not resist sharing the findings. I tried finding the sources of all photos, but could trace back only half.

Rob
No problem with using the photos. I just wanted to let you know where the photos came from.
 
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plncraze

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May 11, 2006
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Peter Left did pilot reports on a few of them. The sail plane wasn't spectacular, the jet required a long take off. Seth Anderson wrote two articles about the prop version which should be required reading before diving into one of these.
 
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