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01-20-2013, 03:43 AM
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Join Date: Apr 2007
Location: Norway, Stj?rdal
Posts: 598
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It's Verner that specify 5/1 outlet area, not UL. UL specify min 20 mm pressure drop at 120 km/h (along with temperatures). The Verner engine is mostly used in Trikes and other slow flying installations, often uncowled. 5/1 sounds reasonable as a starting point for a typical Verner installation to achieve enough pressure drop.
It was a question about gears that works. The Verner gear works, Rotax with the clutch works. It's a design that has a proven track record for simply working. That is why Rotax use a new design with no free play, only clutch (damping) and spring in their new iS. The 912's with no clutch are much more specific regarding propeller inertia (and no CS prop for instance).
It is also interesting looking at 4 stroke outboard engines regarding cc.
75 - 100 hp : 1500cc
100 - 150 hp : 2500 cc
150 - 250 hp : 3500 cc
250+ hp : 4500+ cc
Dan, does the gear run well?
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01-20-2013, 07:39 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by SvingenB
Dan, does the gear run well?
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I'm sorry, I don't understand the question.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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01-20-2013, 08:40 AM
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Join Date: Apr 2007
Location: Norway, Stj?rdal
Posts: 598
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Sorry, I meant the Suzuki conversion with the viscous coupling/damper you mentioned earlier. I'm just curious about how it runs.
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01-20-2013, 09:48 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Quote:
Originally Posted by SvingenB
Sorry, I meant the Suzuki conversion with the viscous coupling/damper you mentioned earlier. I'm just curious about how it runs.
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I think the airplane is with its third owner now. I don't know how many hours are on it. The basic system was a belt drive with a properly sized Lovejoy Centaflex soft element between the crank and the lower sprocket. It replaced a drive purchased from a vendor which had turned out to be a torsional and mechanical disaster (sound familiar?). Mechanical issues aside, the operational problem was a huge resonant amplitude at about 1800 RPM.
I have a good friend who had just finished writing custom software for modeling torsional vibration. He wished to proof the code, so we entered into a project; we would model the old drive, then work the model to determine the inertias and stiffnesses of a optimal drive. I would then design and build a new drive to match the optimized model, which we would then instrument to record mean and oscillating shaft torque for comparison with the code's predictions. And that's what we did.
The math model indicated a maximum (WOT) resonant amplitude over 1500 ft-lbs @ 1800 RPM for the original vendor-supplied drive. We did not instrument that drive.
The new drive matched the code simulation pretty well, and the resonant amplitudes were reasonable. This is a plot of oscillating torque taken from a strain gauge array on the propshaft, steady state throttle. Peak amplitude is now 180 ft-lbs at around 1200 RPM. Still a "prohibited RPM range", but the location is convenient and it won't break the system:
The viscous disk damper was an experimental add-on fired by pure curiosity. Here is the same system as above, but with the addition of the damper:
The mechanical design of the damper was driven by convenience; we were interested in the data, not a product. As a quick add to the existing system it was not very robust, and was removed before the airplane left for a new home. Given the opportunity to properly incorporate a viscous damper, I think it could work pretty well.
__________________
Dan Horton
RV-8 SS
Barrett IO-390
Last edited by DanH : 01-21-2013 at 06:52 AM.
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03-20-2013, 11:28 AM
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Join Date: Jan 2013
Location: US
Posts: 39
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Marcotte
Quote:
Originally Posted by rv6ejguy
The Marcotte boxes don't break but the rubber bushing couplers don't last forever. Depending on the engine and prop, the lifespan seems to be between 150 and 350 hours. Mine were pretty beat at the 357 hour mark. They cost about $60 to change and a few hours, also easy to inspect. Two users have reported much less severe F1/ F2 with heavier flywheels installed so I'm going that route this time as well. Will be an interesting experiment.
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Who actually is Guy Marcotte? Has anyone actually met him?
From Marcotte's website, http://www.glasairproject.com/Marcotte/index.html, it's clear he is not a marketing graduate.
Is he an actual licensed mechanical engineer?
Some guy in his garage with a used CNC machine and a 50 ton press?
A vaporous cloud with a website?
Supposedly Guy Marcotte has been selling these since 1996. That is 16 years. Is he on the verge of retirement now? What happens to the business then?
It's baffling to me that someone has a website selling these psru's, but offers next to nothing as far as information regarding their actual knowledge and educational background. Nor is there any history of the number of units sold, customer contact list, currently flying units, etc. Company profile? Mission statement?
Are they made in China? Who knows?
What type of metal for the various components? Who knows.
Selling them since 1993? How many? 2? 2,000?
In stock? Custom made to order? How long? Payment policies?
Come on man, seriously? This is how you market your product? It's 2013 now.
Guy, how about posting your experience, educational background and product information for potential customers to make an educated purchasing decision from?
In the meantime, I am going to go over to Indianapolis speedway with a wrench and greasy coveralls. I should be able to land a job working on race cars in about 30 seconds, because I have a webpage that shows me with a wrench and greasy coveralls that says "Since 1980."
What more do they need to know really?
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03-20-2013, 12:51 PM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by AL_O_Dine
Who actually is Guy Marcotte? Has anyone actually met him?
From Marcotte's website, http://www.glasairproject.com/Marcotte/index.html, it's clear he is not a marketing graduate.
Is he an actual licensed mechanical engineer?
Some guy in his garage with a used CNC machine and a 50 ton press?
A vaporous cloud with a website?
Supposedly Guy Marcotte has been selling these since 1996. That is 16 years. Is he on the verge of retirement now? What happens to the business then?
It's baffling to me that someone has a website selling these psru's, but offers next to nothing as far as information regarding their actual knowledge and educational background. Nor is there any history of the number of units sold, customer contact list, currently flying units, etc. Company profile? Mission statement?
Are they made in China? Who knows?
What type of metal for the various components? Who knows.
Selling them since 1993? How many? 2? 2,000?
In stock? Custom made to order? How long? Payment policies?
Come on man, seriously? This is how you market your product? It's 2013 now.
Guy, how about posting your experience, educational background and product information for potential customers to make an educated purchasing decision from?
In the meantime, I am going to go over to Indianapolis speedway with a wrench and greasy coveralls. I should be able to land a job working on race cars in about 30 seconds, because I have a webpage that shows me with a wrench and greasy coveralls that says "Since 1980."
What more do they need to know really?
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Marketing has never been Guy's strong point and English is his second language.
He is not a mechanical engineer. As far as I know he was an industrial gearbox technician and machinist.
Yes, he is on the verge of retirement now and the future of the gearbox support and manufacturing is unclear.
Technical info has always been spotty as with all the other auto conversion suppliers and you will not find this sort of reliable unbiased info on most other vendors sites either, usually just glowing reviews, and sanitized statements.
These are not made in China. I believe the gear sets are made in the US and the rest of the parts in Canada. Shafts are 4140, gear housing 6061T6, Timken bearings.
My educated guess on number of units sold is under 300. I know a number of people flying them and I own 3 of them.
Not usually in stock, made to order, minimum wait 8 weeks, max wait up to 6 months. Used to be 50% down and the remainder just prior to delivery.
Yes, Guy could have sold many, many more of these with a proper, informational website. Deliveries have always been slow and communication and contact slow and spotty.
Other than Autoflight in NZ and a handful of others, you will find pretty much all other PSRU makers and FF vendors have limited engineering capability, virtually no real world testing and make unrealistic claims, while keeping failures a bit secret. This is why most are, or soon will be, defunct.
I don't think you will find Guy on this site or any others for that matter.
If you plan to use a Subaru and a PSRU, drop me a PM and I can help steer you somewhere. If you want an easier life, install a traditional engine. 
Last edited by rv6ejguy : 03-20-2013 at 12:58 PM.
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03-21-2013, 11:46 PM
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Join Date: Jan 2013
Location: US
Posts: 39
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Marcotte
Quote:
Originally Posted by rv6ejguy
Other than Autoflight in NZ and a handful of others, you will find pretty much all other PSRU makers and FF vendors have limited engineering capability, virtually no real world testing and make unrealistic claims, while keeping failures a bit secret. This is why most are, or soon will be, defunct.
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Thanks for the info.
It's hard to believe that with all the manufacturing knowledge and equipment in the US, that what we have to choose from is a guy in Canada on the verge of retirement and a guy in New Zealand who may also be on the verge of retirement.
Someone please buy the rights to make the Marcotte gearbox here in the US!
If the guess as to units sold is 300. Take a kit completion rate of about 20%, that would leave 60. You can probably lop off another 20 for guys changing their mind about engines. So there should be about 40 units actually installed in airplanes. The remaining 260 units are probably collecting dust on a bench somewhere.
Who has those flying units?
Do you have all three Marcotte units installed on flying planes?
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03-22-2013, 06:28 AM
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Join Date: Oct 2005
Location: 08A
Posts: 9,500
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Eric,
I noticed you're new here. Welcome aboard. Have you read all the PSRU information in the archives? You'll find it under "Forums" and then "Alternative Engines".
__________________
Dan Horton
RV-8 SS
Barrett IO-390
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03-22-2013, 07:20 AM
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Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
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Quote:
Originally Posted by AL_O_Dine
Thanks for the info.
It's hard to believe that with all the manufacturing knowledge and equipment in the US, that what we have to choose from is a guy in Canada on the verge of retirement and a guy in New Zealand who may also be on the verge of retirement.
Someone please buy the rights to make the Marcotte gearbox here in the US!
If the guess as to units sold is 300. Take a kit completion rate of about 20%, that would leave 60. You can probably lop off another 20 for guys changing their mind about engines. So there should be about 40 units actually installed in airplanes. The remaining 260 units are probably collecting dust on a bench somewhere.
Who has those flying units?
Do you have all three Marcotte units installed on flying planes?
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The gearboxes tend to be sold because they are pricey and easy to unload if a project gathers dust for too long and move onto the next project which may or may not get done.  Certainly, there are not 300 flying now. The bulk of the deliveries were 5-10 years ago. Many auto powered projects have a short flying lifespan or limited hours anyway.
Russell Sherwood is the other notable user of Marcotte. He had multiple failures of 2 other types of planetary boxes, switched to Marcotte a few years back and has had zero issues. He pushes his hard behind a SARL championship winning 6 cylinder EG33.
I am flying only one box at the moment, other is on my RV10 and one is a spare as the future is cloudy. The Marcotte is a solid box but has some minor problems still and could use a better TV solution. I am testing some things soon on mine.
Many people have tried to produce good PSRUs and most have failed due to the lack of engineering and testing. Real World Solutions has a successful planetary box mainly for Wankels, designed by an engineer and it has quite a lot of successful air time. RDM has had a box in development and testing for several years which may be due to be released soon, mainly developed for high power 6 cylinder Subarus. Geared Drives offers a box for Subaru but had an early gear failure for undetermined reasons, that company is under new ownership now but nothing much has happened in the last 3 months with them. There are other PSRUs from Europe, mainly for low powered engines and a another planetary box from Canada but it has had some problems with planet gear lubrication failures.
Read up on torsional vibration here on VAF. This is a vexing problem, especially with 4 cylinder engines.
Autoflight in NZ is still in business I believe but their website has been down for a while. They produce other machined goods, not just gearboxes.
Guy Marcotte may be interested at some point in selling off the design rights, I have not talked with him for a bit.
Just be aware that most auto conversions are not all roses and a good PSRU is often one of the big problems. My standard advice is: if you are not an engineer or gearhead/ machinist/ fab guy/ engine builder, don't go the auto engine route, use a traditional engine.
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03-22-2013, 03:45 PM
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Join Date: Jan 2013
Location: US
Posts: 39
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Quote:
Originally Posted by rv6ejguy
Just be aware that most auto conversions are not all roses and a good PSRU is often one of the big problems. My standard advice is: if you are not an engineer or gearhead/ machinist/ fab guy/ engine builder, don't go the auto engine route, use a traditional engine.
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That is good advice indeed.
It seems like Marcotte has a basically solid product. It would be a shame to see it disappear when he retires. Why reinvent the wheel when you have a product that is very workable within reasonable limits.
Don't get me started on Real World Solutions website. A marketing disaster as far as experimental aviation product goes. Ughhh
I was actively exchanging emails with Phyllis at Geared Drives regarding the LS1 engine. But unfortunately, both her and her father Bud, were killed in that plane crash not long ago. The website is still up, but not updated because nobody else had the passwords to access it. So it just hangs out there in cyberland like a ghost. Bud was the main man with the development. And his daughter was the main administrative person. With both of them gone now, it's unlikely to progress.
Well if Marcotte is interested in selling the rights to make the gearboxes, you may be in a good position to keep the ball rolling if you are so inclined. Certainly better than coming up with a design from scratch.
It would be interesting to find out from him the customer list and who actually has them flying as of 2013.
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