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01-25-2019, 10:13 AM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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My observation of the past comes from Jan rushing numerous things to market before sufficient flight testing was done and customers were left holding the bag to buy "upgrades" and even mandatory "upgrades" to fix multiple problems on engines, ECUs, turbo systems, engines, redrives etc. He also has a history of repressing any talk of failures or even hard questions about his designs.
My question to you was- has he learned and changed the way he approaches new product development, testing and customer feedback?
I can't believe SGF would condone cutting their coupler in any way. This just sounds like a very bad idea to me.
I've met and worked with Jan years ago and he is a smart guy, but no matter how smart we are, we don't know everything as we find out as we get into these projects. I hope Jan consulted SGF before this recommended mod but I strongly suspect he didn't, from past experience.
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01-25-2019, 04:14 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by DanH
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They are both the same link Dan
I am interested in viewing the video
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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01-25-2019, 04:50 PM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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A neighbor and good friend has a experimental Cub powered by a Honda Fit engine with a belt redrive copied from an Enstrom helicopter. The crankshaft pulley uses a center disc out of a manual transmission. At around 700 RPM torsional vibrations will force the clutch springs to nearly bottom out. Virtually no vibration from there on up. His workmanship is top-notch.
The giubo's shown here look nearly identical to the one in my 911 C4.
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
Last edited by rocketbob : 01-25-2019 at 04:56 PM.
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01-25-2019, 06:04 PM
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Join Date: Aug 2009
Location: Longview, Wash
Posts: 479
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Quote:
Originally Posted by Major-Tom
Charlie, you sad earlier that the Viking Gearbox was almost a straight fit. 3 holes lined up excactly and one not. Was it the upper right point (frontview) that needed a little adapter?
And to add one more stupid question... Would you imagine it possible to bolt lycoming style mounting ears to the R18 and use the original Vans engine mount?
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Tom.
In order to use the bolt pattern of the viking gearbox, I did add a 1/2" steel plate that allowed to capture transmission bolt sockets as well as bolts from the gearbox.
I cannot see a viable way to use a Vans mount with an R18 without creating another adapter mount between them. Especially if you had a dynafocal mount. So fir me it just easier to start fresh, with the exception that I use the lower section with the nose gear support - that was Vans OEM.
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01-25-2019, 06:24 PM
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Join Date: Aug 2009
Location: Longview, Wash
Posts: 479
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This topic reminds me of one of the leaseback planes I used to rent. May be a C177RG??? Not sure. But I do remember it was plarcarded with a warning not to stay in a certain RPM range. There was a destructive resonance in that RPM range.
When I get the system operational on the airframe, I would very interested in getting a few planes together and do some vibration testing to see what each plane's characteristics really are. I do know a A+P mechanic who does some advanced testing, I will see if his equipment can do this type of testing. I think it does.
As far as the picture of a cut disc a few posts back I did not see any information that explained anything.
To strive for information and knowledge we should all look for successes, and failures and learned as much as we can from all sides.
And of course, lets keep it friendly.
Thanks
Charlie
Charlie
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01-25-2019, 08:57 PM
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Join Date: Aug 2009
Location: Longview, Wash
Posts: 479
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I think it is a very good idea for people to test their powerplant set ups to learn where the troubling harmonics are. It is great if the operational frequency can be found low enough in the RPM to be able to transition through it at a lower power settings.
It is also great if you can have the higher harmonic somewhere above the operational range, say 5500 rpm.
I also think it is a great idea to buy friends beer at OSH. But it wont be because someone called me a fool for using the term "dampner" instead of "coupler". Geesh, that is a bit over the top!
Also, I think it is circumspect to bash the land of the Vikings without having any idea what testing they have done, or not done. May be, just may be they did that testing and found that by sectioning the flexible disc, it moved a troubling harmonic up past the operational range? I personally don't "like" the idea of sectioning the guibo, but we really don't have enough informatin to be critical of the decision - other than - it sure goes against what SGF had in mind...
Charlie
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01-25-2019, 09:22 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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I'm pretty familiar with what Jan has done over the years being a supplier to him for several years and following the Viking project from the start. I'm also privy to lots of feedback and information from customers who came to me for advice and ECUs who were unhappy customers of Jan. Information most other folks never hear.
To be fair, I've also talked to quite a number of his customers who have been pretty happy with his products too.
Nobody should be won over by some pretty CNC work you see on the outside. Just like people, it's what's inside that really counts.
You don't need to be an engineer to design a successful redrive as we've seen some examples designed by experienced gearheads and machinists which work well with few problems but it's probably pretty helpful.
You could have excellent service and reliability from this drive but the cutting of an engineered coupler (not actually designed for this drive in the first place) is a big red flag to me. I'd urge you to try to learn more about this aspect from Jan if possible. Asking some hard questions might enlighten you and save you some trouble down the road (or get you excommunicated).
We want you to succeed and I'd like to see something like the Viking drive be reliable and reasonably priced and readily available for others who want to experiment with auto conversions because too many other drives are priced way out of the marketplace IMO.
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01-26-2019, 12:22 AM
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Join Date: Aug 2009
Location: Longview, Wash
Posts: 479
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Ross
I appreciate that you are respectful of others even when you disagree and you offer constructive criticsm that is not offensive. Then you end it with genuine hope for success and safety. Well done.
I have posted on the Viking forum on the Zenith page an open letter to Jan asking why he cuts up the discs. I asked if there was engineering behind that decision and if so, if he would share it with us. I also asked if there were problems with using the disc whole. I just posted it earlier in the day. I have not heard back. I suspect he will answer it. when he does I will share it here.
I also want to dig towards any failures of the discs and try to learn what cause the failure. IF they are out there it will be easy to find them..
It reminds me when IVO has several props failing about a decade ago. People were furious and wanted him lynched. The fact is the issues were mostly cause by some end-users not properly following the installation instructions and I believe IVO instituted some improvements along the way as well. Today, there are few troubles with IVO props. Some give them high tumbs up. Others a big thumbs down. Yet they are using the same prop, with some improvements they have learned along the way.
I really would like to test my set up for resonance frequencies once I get farther down the project. Hopefully I can fine someone who is experienced and does not cost too much had has good equipment. Right?
Charlie
Last edited by charosenz : 01-26-2019 at 12:24 AM.
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01-26-2019, 09:20 AM
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Join Date: Aug 2009
Location: Longview, Wash
Posts: 479
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To strive for information and knowledge we should all look for successes, and failures and learned as much as we can from all sides.
There is only one side here, and it is yours. This is all written to help you. You asked for real world experience, and this is what it looks like.
Your comment about there only being "one side and it's yours" is not accurate, and came across as disrespectful. Anyone following this thread will know I am open minded welcome comments as long as they are respectful. People will generally value and receive your posts if show them respect.
Please keep this in mind as you share information.
Thank you.
Charlie.
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01-26-2019, 09:39 AM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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OK, no dog in this fight-------just a couple observations.
Quote:
Originally Posted by DanH
There is only one side here, and it is yours. This is all written to help you. You asked for real world experience, and this is what it looks like.
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Quote:
Originally Posted by charosenz
Your comment about there only being "one side and it's yours" is not accurate, and came across as disrespectful.
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A matter of perspective IMHO-------I saw nothing disrespectful in Dan's statement.
Quote:
Originally Posted by charosenz
People will generally value and receive your posts if show them respect.
Please keep this in mind as you share information.
Thank you.
Charlie.
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I, and I suspect many other VAF members value Dan's posts no matter how they might interpret his delivery.
__________________
Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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