Wanted BD-5 Kauth Drive Plans

Discussion in 'For Sale / Wanted' started by daveklingler, Feb 19, 2019.

1. Feb 19, 2019

daveklingler

Active Member

Joined:
Jan 23, 2013
Messages:
41
6
Location:
Albuquerque
Per a discussion with on a different BD-5 wanted thread, I'm looking for someone who would be willing to take photos of a set of Kauth drive plans for a BD-5.

I'm volunteering the time required to model each piece of the drive in SolidWorks. I'll upload the model and drawing files to a few different websites so that current and future BD-5 builders can have access to the resource.

Many thanks!
Dave Klingler

Norman likes this.
2. Feb 23, 2019

daveklingler

Active Member

Joined:
Jan 23, 2013
Messages:
41
6
Location:
Albuquerque
Bump. Still looking.

3. Feb 23, 2019

Hot Wings

Well-Known Member

Joined:
Nov 14, 2009
Messages:
5,754
1,871
Location:
Rocky Mountains
With this picture you can at least get started. Guess at the dimensions and correct them as you find them? Isn't parametric nice?

Some of the dimensions can be taken from the BD-5 plans. Some of the parts are OTS. I don't know what clutch was used but IIRC it too was an OTS unit. The dimensions and alloy of the torsion shaft (upper right) are also findable on the net. The original Kauth pulleys were machined, IIRC, out of phenolic and wear was a problem. The ones in the photo look like hard anodized aluminum. Probably best to update to modern belt designs.

4. Feb 24, 2019

daveklingler

Active Member

Joined:
Jan 23, 2013
Messages:
41
6
Location:
Albuquerque
I've seen this photo, but I'd assumed this was the AT-6 model - converts a Texan to a radial pusher...
I've considered doing what you suggest, but it sure would be a chore compared to just modeling the parts from drawings. Materials would be nice, too.

I thought at first that there was no real damping in the Kauth drive, but I'm starting to think that I see two black rubber discs with six aluminum bushings apiece in them. I've never seen anything like that before; I've only seen the reverse.

5. Feb 24, 2019

kent Ashton

Well-Known Member

Joined:
Aug 15, 2008
Messages:
712
201
Location:
Concord, NC
The plans for the drive system do not come with any dimensions except length. Probably Gerry Kauth had detailed blueprints but the plans are drawn assuming the builder bought the drive and just needs enough info to install it. The materials are not specified. There is a metal sprag-clutch build-up with no dimensions (upper left in the pic above). It uses an interference fit of a 4-leaf metal cone into an aluminum cone and the whole assembly is press fit over the drive tube and secured with a left-hand bolt that tightens the cones against the drive tube. It takes a fabricated puller to remove the assembly and likely you would have to take the rear of the fuselage off the rear to service the center and rear bearings. There are several aluminum castings and of course, the belt drive pulleys to find or make as well as the final adaptor to your engine of choice. Sheet metal parts are drawn to mount it in the fuselage that aren't shown in the picture above. I've never heard of any blueprints complete enough to hand to a machinist.

A wild guess at what a machinist would charge to make one might be $3K-$5K. The only way I can see that it justifies the cost and trouble is to order a dozen and sell them to builders. However my short experience was that builders are reluctant to pay more than \$3K for a BD-5 on the gear _that_includes_a complete_drive_system so good luck with that.

Even then the pop-riveter-and-tin-snips shop that Bede implied was all it took to build a BD-5 really turns out to be a fully equipped shop with a bandsaw, mill, lathe, sheet metal bender and bender dies, pro-seal gun or again, you farm stuff out to a machinist. If you have that shop, then you have to deal with the weak wings, the weak brakes, the missing parts, the missing jigs that Bede was planning to supply in his builder centers, the incomplete plans, the lack of newsletters, the, private Facebook discussion groups (yuck) or locked-up Yahoo groups. There is no real builder support although professionals will build them for a price. I expect these folks do not want to spend hours on the phone advising BD-5 dreamers.

This is why I wouldn't publish the drive system plans I had and say "go for it boys." It is a colossal suck-hole of wasted time and money for innocents who see the jet airplane and think they're going to build a cheap prop version like they'd build a model airplane or a Vans pre-punched kit.

I am just explaining why there are 4000+ kits moldering in garages. I built a Cozy Mk IV, a Long-EZ and most of an RV-6 from scratch. They were a piece of cake compared to the BD-5. However, it is a great airplane for learning sheet metal work.

Last edited: Feb 24, 2019
Norman, DangerZone and BoKu like this.
6. Feb 24, 2019

TFF

Well-Known Member

Joined:
Apr 28, 2010
Messages:
10,915
2,920
Location:
Memphis, TN
The black donuts are driveshaft joints, those look like Mercedes. Many European cars use those instead of u joints because they have a little constant velocity action and don’t have to be aligned perfect. Easy to make a mount for.

7. Feb 24, 2019

Hot Wings

Well-Known Member

Joined:
Nov 14, 2009
Messages:
5,754
1,871
Location:
Rocky Mountains
But can get tricky with regard to TV. There is often a preload specified which means compressing them in diameter before the bolts will line up. Changes the stiffness of the system.

8. Feb 24, 2019

TFF

Well-Known Member

Joined:
Apr 28, 2010
Messages:
10,915
2,920
Location:
Memphis, TN
Easy to make a mount was about triangle bolt pattern squared to the shafts. The other parts are the problem of the builder.

9. Feb 25, 2019

STDJantar2

Member

Joined:
Jan 31, 2008
Messages:
18
8
The damping seems to be provided by the rubber donuts and the torsion shaft. You can adjust the damping by tailoring the torsion shaft but will need a very througout study on the harmonics.

10. Mar 2, 2019

daveklingler

Active Member

Joined:
Jan 23, 2013
Messages:
41
6
Location:
Albuquerque
I'll be darned.

https://www.partsgeek.com/gbproduct...5+68-71+Mercedes+Drive+Shaft+Flex+Joint+70+69

I wonder whether the other triangular parts in the photo above are Mercedes parts as well. If so, that would put a major dent in the task of manufacturing; many of the other parts are off-the-shelf.

I wonder whether Gerry Kauth had previous experience with Mercedes repair. That might be a clue where to look for some of the other pieces.

11. Mar 2, 2019

daveklingler

Active Member

Joined:
Jan 23, 2013
Messages:
41
6
Location:
Albuquerque
12. Mar 2, 2019

plncraze

Well-Known Member

Joined:
May 12, 2006
Messages:
1,346
261
Also look up Guibo

13. Mar 4, 2019

Geraldc

Well-Known Member

Joined:
Nov 12, 2011
Messages:
88
25
Location:
nz
Similar rubber couplings are also used by aeromomentum.Belts and pulleys can be sourced through speed shops as they are used for blower drives and are now available with high strength belts.

14. Mar 6, 2019

daveklingler

Active Member

Joined:
Jan 23, 2013
Messages:
41
6
Location:
Albuquerque
Interesting. I thought that Aeromomentum manufactured their own spur gear drives. Do they currently offer a drive that uses a dampening coupling, or is it used somewhere else?

15. Mar 8, 2019

Geraldc

Well-Known Member

Joined:
Nov 12, 2011
Messages:
88
25
Location:
nz
Aeromomentum use their own gearbox with a rubber coupling between the flywheel and the gearbox.

16. Mar 10, 2019

Joined:
Jan 23, 2013
Messages:
41