Engines to replace the dominance of Rotax

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GTX_Engines

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Well aren’t you special ...


BJC
Perhaps you're right, too much information. I was writing to instill confidence but I've gone overboard so I'll edit out the info about me, who I am, what makes me tick, past mechanical info that is relevant and how all that affects what I do now in the way of helping other pilots by providing the best power and reliability for the least weight & cost. Onwards and upwards.

Rule # 17: Never call a pilot on Saturday morning.

Rule #1? Never talk religion or politics to another pilot.
 
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GTX_Engines

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May 17, 2013
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Atlanta, GA
Have you thought about offering complete firewall forward kits for your Yamaha engine conversions? I'd say you would have all the business you could handle (and then some) if you did.
We do offer complete Highlander and Kitfox FWF kits, as well as for Air Command gyroplanes like the one in my avatar. I don't fabricate everything for complete kits in-house (except gyroplanes, I do all that myself), rather I partner with the other airplane builders and provide a single-source point of sale to the customer.
 

Victor Bravo

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If you were writing to instill consumer confidence, I might humbly recommend that you pull the throttle back about halfway and close the nitrous valve. In sales, credibility and communication style are equally as important as product advantages. Although I am not permitted to discuss the actual details of the product here on this forum, I have significant personal experience with this subject (trying to sell an aviation related product by way of internet forum presence), and I can GUARANTEE you I have made this type of error and paid a very serious price for it. Forgive me for soundling like Hulk Hogan in the old "locker room interview" on Wrestling, but... "I know what I'm talking about, brother".
 

GTX_Engines

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If you were writing to instill consumer confidence, I might humbly recommend that you pull the throttle back about halfway and close the nitrous valve. In sales, credibility and communication style are equally as important as product advantages. Although I am not permitted to discuss the actual details of the product here on this forum, I have significant personal experience with this subject (trying to sell an aviation related product by way of internet forum presence), and I can GUARANTEE you I have made this type of error and paid a very serious price for it. Forgive me for soundling like Hulk Hogan in the old "locker room interview" on Wrestling, but... "I know what I'm talking about, brother".
Well said, and well taken, thanks.
 

Vigilant1

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GTX,
I was quite interested in the Yamaha 4 cylinder Genesis engines a few years ago.
What follows is some feedback, not a criticism: As a potential customer, I found it very hard to figure out exactly what you were selling. You had a presence at various trike and gyro sites and elsewhere with lots of iterations of induction systems and PSRUs, apparently these represented the evolution of whatever products were presently for sale at Mohawk. Add to this various YouTube videos by users showing things that might have been bought from you at an unspecified previous date, and it only added to the confusion. The Mohawk web site didn't provide specifics on the latest variant of what was for sale, and I made an email inquiry that went unanswered. So, looked elsewhere.
In response to your post, I just paid another visit to your web site. It still is not good, IMO. There's no general outline of what is involved in building a flying conversion. I went to the "shop" tab and then "PSRUs" . . .
. The site says "THIS PAGE HAS NO PRODUCTS TO SHOW AT THE MOMENT." What? I thought that was a big part of what Mohawk offers. Not even a picture of the redrive on the site. Hmm. Okay, "Shop Engines"...produces nothing but greyed-out text about Steve Henry's Highlander (I get that you are proud of it, but the same couple of paragraphs appears on a lot of pages in your site).
Do you sell kits? There's a banner that says so, but no more info.
Folks coming to your site want to know about the steps needed to convert a sled engine to airplane use. They want to see real-life HP info, weights, and cost information. Sure, every installation is different, but if I want to use an Apex engine in my XXX, what are the costs, weight, and HP I can expect? Do I need to find my own used sled engine, or do you sell them? (Not shown on your site). The site says 21 of your conversions are flying--super! In what? Any photos?
Maybe you have all the business you can handle, so there's no need to roll out the welcome mat. But if you want to be the go-to guy for putting these very promising sled engines into airplanes, and you want to sell a lot of them, then I think it would be worth your time to enter your site as a prospective customer would and see if it could be improved.
(I would have sent an email, but the last time that didn't work for me.)
 
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Victor Bravo

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Steve Henry is famous for his "dead stick takeoff" demonstrations, proving that you don't need to buy an engine to go fly a STOL plane. Not the best poster child to sell engines, eh?

(I'm kidding, Steve is a fantastic pilot and a very nice guy, He's earned 100% of his celebrity status I'd be happy to have him as a factory rep for any bushplane product)
 

choppergirl

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Choppergirl's Flying Circus ★★☠★★ AIR-WAR.ORG
I am obliged at this point to mention Dana's most excellent idea. A 103 scale Spruce Goose with eight chainsaw engines.
Someone, please, build it!
There were some 103 4 engine Flyers... by a dood named Kolb

I'm not sold on the Rotax's, because the ones that run like a champ are the ones that have Thousands of $$$ poured into them of regularly scheduled maintenance and overhauling, sent off to some Rotax expert. Not exactly a fair metric to judge all Rotaxes by only the ones that get red carpet, white glove, clean room treatment.

I've read some Rotax people even replace all their spark plugs on their plane after every 20 hours of use. Really? Really? A bit excessive muchly? My motorcycle has been running with the exact same spark plugs since it rolled off the factory floor in in 1985...

Take a neglected Rotax out of a snowmobile graveyard, and I bet it will run really not much better or any more reliably than any other brand neglected snowmobile engine out of the same graveyard.

I have never seen an engine in my life that wasn't neglected to some degree. The ravages of time and use are relentless. Given any amount of time, all engines end up covered in oil and dirt, with wearing out parts and flaking off paint and aging plastics and wire and carbon deposits.
 
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pictsidhe

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Jul 15, 2014
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North Carolina
For those that are trying to avoid redrives, ducted propellors run efficiently at much higher revs than an equivalent horsepower prop. Not that they are simple to get right, either...
 

brehmel62

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Jul 12, 2011
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83
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Farmersburg, IN USA
Looks like most of the engines you are looking at from the web address are 4 stroke. My opinion is that to compete for that engine size with the competition, 4 strokes will need an EMS, Fuel Injection and be Turbo-Supercharged. Direct drive isn't practical at the RPM's necessary to obtain reasonable power to weight ratios so a propeller speed reduction system will also need to be part of the solution.
I seem to recall that the last time I went over propeller loading that you could do up to about 65 HP with direct drive with your engine revving to 3,600 RPM and a 56" propeller. Let me check at Great Plains to see if that matches.

Looks like they go up to 76 HP with direct drive. Let's double check that.

Cessna 152: 110 HP, 72" prop. That's a prop loading of about 1 HP / square foot.
That would be a 56" prop with 65 HP, so that seems to match.

I don't really understand the part about turbo-charging. Fuel injection can be handy because it gives you automatic mixture control with altitude, but there do seem to be other, cheaper options and I doubt most would fly higher than 7,000' anyway.
 

GTX_Engines

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May 17, 2013
Messages
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Atlanta, GA
GTX,
I was quite interested in the Yamaha 4 cylinder Genesis engines a few years ago.
What follows is some feedback, not a criticism: ................ng sled engines into airplanes, and you want to sell a lot of them, then I think it would be worth your time to enter your site as a prospective customer would and see if it could be improved.
(I would have sent an email, but the last time that didn't work for me.)
I open my email every morning and don't go to the shop until each and every msg received at Info@MohawkAeroCraft.com is opened, answered and filed in a folder with the person's name on it.

35 of these new MAC email folders were opened in the first 70 days of 2019 alone - a new inquiry every other day. That's new folders, not returning customer's or questions from a person who already has an open file.

I often spend entire days - not just hours - answering questions by email or phone and providing pricing to people who never spend a nickel. It is now 3:06PM, I have been working since 8:30 AM and yet I have not accomplished a single thing towards moving the orders that are waiting on my shipping bench and stacked 6-deep behind that. Why?

Because a guy packed up his wife, the kids, and the dog and hauled an Air Command Tandem gyroplane behind his motor home RV from Columbus, IN down to my shop in Columbia, SC and arrived here late last night - too late to offload in the dark - so I could install a ground-breaking, first-ever 165 HP Apex with EXUP valve. He was supposed to be here during the day, but as with many long family trips this one had delays and I had to instead carve time out of a booked schedule to accommodate him today.

I enjoyed the heck out of it, off-loading the gyro while his kids bounced on the trampoline in our backyard, zoomed up and down the street on their bikes, meeting his four wonderful kids and sweet doberman. His wife was so nice, and funny, and they left me with a bottle of their craft-made mead. Can't wait to uncork it tonight and do a taste-test with my wife when she gets home from work. Actually didn't mind getting a little behind in my other work, ya know?

We had a much better website prior to the one you see now until a while back when the webmaster's server got hacked, and thousands of websites he provided were down for an extended period. That included my email address. I got fed up after waiting after 6 weeks for my site to come back up and built my own using WIX and a new domain www.MohawkAero.com (the original site was www.MohawkAeroCraft.com).

For several more weeks there problems getting the original email domain to bounce with the new one and service to re-route.

Perhaps you wrote sometime during this period, hm? Sorry you were more patient and couldn't send another back then - or even now as I have since posted the address again, here.

If you would kindly write an email again, I always do respond within 24 hrs. unless there is some other problem: an act of god, or server is hacked or kaputsky.

I am aware of short comings on the MAC website, pages with no photos yet. Hopefully I will find the time, energy and patience to finish the pages that are still under construction very soon. Meanwhile, the other pages are populated for clutches and adapters, and if you want more info and pictures please take a second or two and fill out the contact form on the bottom of the landing page ("Home" page), hit the <SEND> button, and you will receive a response with a 10mb ZIP file containing all the info you need to get started.

I do not provide assistance on how to pull an engine from a sled. I do offer assistance, with everything I possibly can where needed, to install these engines on aircraft and air boats, starting with budgetary prices for engines.

When I am assured that someone is ready to order we contact our many suppliers who salvage the parts and motors we need off of the sleds, and provide the customer with year, miles and prices for all known sleds available on that particular day. The supply changes daily, so I don't do this until it is time to place an order.

The motors are either drop shipped to the customer's shop/ home or shipped to me for bead blasting and basic tune up, plugs and oil filter, plus installation of the PSRU and shaft coupling.
 

CDNRV7

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Nov 22, 2014
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Saskatchewan Canada
Which model/year of Yamaha sled has the 4 cylinder carburetor engine? Is the FI an option to consider? How many miles on the sled would be considered as acceptable for an aircraft conversion?
 

GTX_Engines

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Atlanta, GA
Which model/year of Yamaha sled has the 4 cylinder carburetor engine? Is the FI an option to consider? How many miles on the sled would be considered as acceptable for an aircraft conversion?
Mohawk Aero Facebook group " Yamaha Aircraft Engines", clicks here https://www.facebook.com/groups/1251356951570824/

To answer your question directly, all 2003-2005 998cc Yamaha Genesis 4-cylinder (YG4) RX1 model, and 1048cc YG3 Vector etc. were carbbed. In 2006 all YG4 and YG3 engines were updated with EFI. The RX1 model was disco'ed and changed to Apex for YG4, still the same basic engine but with about 6-7 lbs of weight shaved off and different cam grind which provided a little more HP in most years, but not all. YG3 Vector was replaced with the EFI version called a Nytro. These YG3's produce 130-140 HP, depending on year.

In 2014 Arctic Cat began using YG3's in their 7000 series sleds.

In 2017 Yamaha introduced the turbo Sidewinder advertised at 180HP. Many dyno'ed at well above that, so lots of folks refer to them as 200HP engines. Arctic Cat put them in some of their 9000 series sleds beginning that same year.

2018 saw the last YG4's, no more Apex sleds built.
 
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GTX_Engines

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Atlanta, GA
Yamaha aircraft engine conversion history:


2007 Todd Reick completes and flies in Colorado; then showcases the first successful YG3, 120 HP (Vector sled) on his single-place Air Command gyrocopter, at the PRA annual international gyroplane and rotorcraft convention at their airport in Mentone, IN in August.


2008 Todd starts fabricating and selling the first YG3 conversion kits based in CO. These kits utilize Rotax C boxes and RK400 centrifugal clutches exclusively.


2012, November, Greg Mills completes and flies in Atlanta, GA; then in 2013 showcases the first successful YG4, 140 HP (RX1 sled) on his Air Command tandem seat gyroplane, at the annual Bensen Days Gyrocopter convention at Wauchula, FL


2013 Greg starts fabricating and selling the first YG4 conversion kits, and launches Mohawk Aero Corp. (MAC) based in Atlanta, GA. These kits utilize Arrow, SPG4, Hirth, and Rotax C gearboxes, with RK400 centrifugal clutches and rubber flex-shaft couplings (no clutch), internal sprag clutches (Arrow), and "BMW" (not really made by BMW) centrifugal clutches.


2014 Teal Jenkins launches Skytrax, based in AZ, to compete with MAC.


2015 Greg showcases the MAC Silent Drive PSRU at Mentone in August, a Hy-Vo chain redrive which also includes a break-away clutch for prop strike protection (similar technology as Rotax 912/914 gearboxes), mounted to an RX1 YG4.


2015 Tango Gyro introduces at Bensen Days, in April, the first production (quick-build experimental kit) aircraft designed around the exclusive use of YG3 and YG4 engines, based in Atlanta, GA.


2017, January, Greg introduces the first viable alternative to external centrifugal clutching - the MAC GT4 roller ramp clutch.


2017, February, Greg introduces the first production Apex (EFI) 150HP YG4 "GTI" kit (yes, they are quite different from the RX1), for use with the MAC AK7 gearbox, and Arrow, SPG4, Hirth, Simonini C, and Rotax C and E gearboxes; to utilize GT4, RK400,"BMW", & Tango clutches, as well as MAC heavy-duty (not Rotax "rubber donuts", which fail very quickly under the power of the YG3 and YG4's) rubber flex-shaft couplings. The first GTI sold goes to Steve Henry, who puts it on his Highlander “Yee-Haw 6”. The 195 HP NOS-boosted airplane wins every STOL competition, and the Grand Champion Award, at Airventure 2018.

*************************************************

This year we have seen some exciting new projects unfold and enter testing. One is the complete tear-down and rebuild of an Apex YG4 by a company in Finland, which is to be sold to Steve Henry who anticipates using up to 300 HP of the available 500-600 HP by means of turbo boosting. This engine is going to perhaps test the limits of a new Skytrax “2-stage”, 3 gear PSRU which is designed as a bolt-on unit to place the prop as high up as it can for tractor prop size increase. The gearbox has an integrated sprag clutch design copied from the out-of-production Italian Arrow gearboxes found on Arrow 2-cycle boxer motors (500 & 1000cc) popular in the gyrocopter community in the 1980’s and 1990’s.


MAC began work this year on the first Apex (2011-2018) EXUP conversions, a stock-out-of-the-box 165HP YG4; installing one an Air Command tandem gyroplane and a second on a ($100k+) Trendak side-by-side gyroplane. MAC just finished their first Phazer YG2 80 HP conversion kit this week, which is going on a Quicksilver Sport II.

Finally, MAC is ordering material and parts for the first Sidewinder YG3 180-200 HP turbo conversion, which is to be installed on a one-off, customer-built, tandem gyroplane this year. The customer is winding down the snowmobile season in Nebraska playing with his 2017 boosted beast, after which he will pull the motor and start building the rotorcraft. This is perhaps the most exciting news of all for folks interested in hypo power at very light weight in a truly tried-and-tested package on sleds en proven over the course of the past several years. With two popular makes utilizing these truly awe-inspiring boosted engine which have taken the sledder community by storm, plenty of engines and parts are sure to be available at very good prices, a mere fraction of what a 115HP 914 goes for, let alone a 915.

Onwards and Upwards! Check out the MAC Facebook page for all the latest & greatest updates from MAC, including informative postings which provide engine dimensionals, weights, dyno charts, etc.
 

henryk

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krakow,poland
Looks like most of the engines you are looking at from the web address are 4 stroke. My opinion is that to compete for that engine size with the competition, 4 strokes will need an EMS, Fuel Injection and be Turbo-Supercharged. Direct drive isn't practical at the RPM's necessary to obtain reasonable power to weight ratios so a propeller speed reduction system will also need to be part of the solution.
https://www.ojovolador.com/eng/read/tests/bailey_v5/

-practical opinion ?

(for KASPERWING, 75 kg empty...
I want to replace 2-stroke G-25B engine.)

20190503_132256.jpg 20190422_181852.jpg
 

blane.c

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capital district NY
Of the pictures to much complexity? Additionally the weight of all the bracketing required to constrain it. It doesn't speak to the simplicity and freedom of flight that the rest of the aircraft alludes to.

G25B.png

The G25 B 20hp, 38.6lbs without redrive?
Even a simple hand carved wooden propeller direct drive on the twenty horse engine is likely better because of the power lost in the transmission of the counter geared unit and considering the added weight as well.

I do not know your weight constraints in Poland. But seeing you would consider a Bailey 4 stroke, a GY6 hopped up with the un-necessary's hacksawed off.

Maybe more cubic inches would help? With a simpler propeller?

You know I like multi-engine, maybe a pair of Radne Raket engines? https://www.radne.com/Products/696/Aero around 7.2kg each including redrives.

One in tractor and one in pusher on the boom? Woot! There you are, counter rotating propellers and no gearing.
 

bmcj

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