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SDS Aero Products Flywheels

rv6ejguy

Well Known Member
We've just completed the first batch of production flywheels for Lycoming engines. These are machined from 6061T6 billet and are available in either 5/8 or 3/4 inch prop lug versions. Weight is about 1 pound less than the factory Lycoming part. Initially, only 149 tooth ring gear versions will be available.







These will be available with the SDS crank trigger magnets mounted or virgin as you see here. Cost has not been finalized yet but it looks like we may be able to price below the factory and other aftermarket choices currently out there.

Hopefully these will be available for sale in early August.

These are the first parts to be offered under our new SDS Aero Products umbrella also debuting in August with a new logo and new aviation-only direction. You'll see a growing line of new CNC'd bits and electronic EFI/EI controllers for Lycoming, Continental, Rotax and Jabiru engines in the future.

After struggling to keep up for the last couple of years, we finally have enough production capability available to branch out into other areas like this.

We're always looking for customer ideas/ feedback on new features or parts you'd like to see us produce.
 
Wow does that ever make the Lycoming sand cast parts look, well, um... ugly! As usual, a solidly superior part from a solidly superior supplier.
 
Wow, Those look great.

What, if any, are the advantage or disadvantages of a lighter flywheel?

This would be cool to have on a new Aero Sport engine, especially if I didn't have to pay for the original one :D
 
Wow, Those look great.

What, if any, are the advantage or disadvantages of a lighter flywheel?

This would be cool to have on a new Aero Sport engine, especially if I didn't have to pay for the original one :D

Lycoming calls them Ring Gear Supports, really not much flywheel effect compared to the prop inertia. Many of the STOL guys want to trim every ounce off the plane possible.

We think a lot of the engine building shops may like these for new builds.
 
Any plans to anodize them? They look great.

We're a little reluctant to anodize parts like this due to unknown long term fatigue characteristics and the surface finish for the ring gear interference fit. It might be ok but we'd prefer to do more analysis before offering anodized ones.
 
Are you going to be making any dual ring gear models?

The 149 tooth ones are more popular so we built those first. We'll see how sales go and if there is a decent demand for other types, we'll probably make them.

The initial costs for CAD and new tooling/ fixturing to build the prototype part add up. We have to recover development costs first before moving on to new designs.
 
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Those are a work of art. Are you using the same style starter ring that is replaceable if teeth are broken?

Vic
 
Thanks.

Yes, using a PMA'd ring gear part but if you use SDS you won't break any starters or ring gears of course...;)

If people wanted a solid version for better air sealing, that would be cheaper as we wouldn't have to machine all those holes in there.
 
+1 for a dual pulley version! Looking forward to seeing some aircraft with SDS installed next week at OSH.
 
We have to go with the most popular models first. I'd guess single sheave flywheels outnumber the dual ones at least 20 to 1. Hard to justify the tooling costs and low production numbers in my mind. There are already existing suppliers for those parts.
 
After some supply problems on the ring gears and having to add some new equipment to install them, we finally have these for sale now in limited quantities. I'm still waiting for another shipment of ring gears, likely to get here in the first 2 weeks in Sept.

Price is $620US without SDS magnets installed, $650US with magnets installed.
 
Ross,

Any plans to produce this with the multi rib (serpentine) style belt?

Not at the moment until we recover the CAD programming/ prototyping costs. There would have to be sufficient demand to justify starting on this.

We can make a solid version of the current one quite easily for those who want ultimate spinner air sealing.

Looks like we'll be doing a second production run in the next 30-60 days.
 
I started making a lightened 360 flywheel a few years back with my trusty Smithy. Just the work I've done made the flywheel noticeably lighter then a stock one. I suppose I should finish it. They do get some weight off the nose.

Flywheel.jpg
 
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The SDS Aero flywheels are selling quite well so next production run is likely to begin in early Sept. If anyone wants one with no lightening holes, let us know soon.
 
The SDS Aero flywheels are selling quite well so next production run is likely to begin in early Sept. If anyone wants one with no lightening holes, let us know soon.

Won't that mess up your inventory of lightening holes?.........:D
 
Anodized testing

We clear anodized one of our billet flywheels at a customer's request who agreed to do beta testing and report any negatives in use on his engine. Hopefully it all goes well after inspection and we can offer this option next year to other customers.

 
Ditto tool builder

I have a Skydynamics on my 0320 -3. Both Skydynamics and Ross say no way to add CPI. However, I am investigating bolting magnet holders on the skydynamics because I am dying to put one of my CPI's on the -3 and compare to the Pmag on the other side ;) My new 0360 -4 will be CPI. If I have to, I will get a new wheel from Ross and sell my Skydynamics if anyone wants it.
 
If you designed and fabbed a different sensor mount, you could mount the magnets in a fore/aft plane like LS does. We had a customer with the small flywheel do this on an O-320. Worked fine. I could post some of his pix here if that would be helpful.

You have to do your own indexing but if you're handy with a mill and lathe, not so hard.
 
Harmon Rocket ?Race 57? uses a Sky Dynamics flywheel & I was able to come up with a sensor bracket for it.
PM me with your email address & I will send you a drawing.
 
Well that's a problem unless there's another way. I still like the aft mounted alternator, though.

Well, I overstated the "problem"...Certainly it would not be hard to manufacture a sensor mount and hang the magnets elsewhere, but you simply miss out on the pre engineered, bolt on stuff from SDS.
 
Fresh off the lathe



Our machine shops are catching up on parts demand now after maintenance and vacations.

This is the first of over 300 parts expected before the end of this week. Hopefully we can start filling some outstanding orders after Reno.
 
We're looking at running some more variations of our flywheels, one for those not running a front mount alternator. How many people might be interested in one without the belt groove? It would be lighter and less expensive than the current model. It would not be able to be used with our current magnet and crank sensor setup however, being aimed at those with other ignition systems primarily.
 
... It would not be able to be used with our current magnet and crank sensor setup however, being aimed at those with other ignition systems primarily.

But the whole point is to use your ignition system (and FI) AND save weight. So that means you need to design a new magnet and crank sensor setup. I know you don't have enough to do, so get to it!
 
But the whole point is to use your ignition system (and FI) AND save weight. So that means you need to design a new magnet and crank sensor setup. I know you don't have enough to do, so get to it!

We are open to people using our flywheels with other ignition systems, even mags. If the numbers were there and we had more spare time, we could develop a new pickup and magnet mounting for those wanting to eliminate the belt driven alternator. How many would be interested in that?
 
We are open to people using our flywheels with other ignition systems, even mags. If the numbers were there and we had more spare time, we could develop a new pickup and magnet mounting for those wanting to eliminate the belt driven alternator. How many would be interested in that?

What would be nice if we had a simple A/B cost and weight comparison showing a complete SDS solution for FI and EI and B&C rear alternator vs conventional FI, mags and front alternator.

For example, something we could order from AeroSport Power as a build option on an o-340 or o-360.

I have a feeling that costs are roughly comparable, but you get the modern SDS solution and all it's benefits. It would be a perfect setup for those looking for max HP/weight in a Lycoming type solution. I will need a new engine soon and everything I can do to reduce weight and move the cg aft is important.
 
What would be nice if we had a simple A/B cost and weight comparison showing a complete SDS solution for FI and EI and B&C rear alternator vs conventional FI, mags and front alternator.

For example, something we could order from AeroSport Power as a build option on an o-340 or o-360.

I have a feeling that costs are roughly comparable, but you get the modern SDS solution and all it's benefits. It would be a perfect setup for those looking for max HP/weight in a Lycoming type solution. I will need a new engine soon and everything I can do to reduce weight and move the cg aft is important.

I can weigh all the SDS components but don't have access to all of the legacy bits. I will go up the street to Ralph's and see what relics I can find and weigh.
 
I have some weights here:

Bendix mag 4 cyl. non-impulse with harness 6 lbs. 6 oz

Slick mag 4 cyl. non-impulse with harness 5 lbs. 11 oz

O-320 carb 3 lbs. 3 oz

O-360 carb 5 lbs. 5 oz

I didn't have a mechanical fuel pump to weigh but let's round that off to 1 pound with the drive rod.

Rounding things off on a 360, that's around 18 lbs. for the ignition and fuel systems. Not sure what a Bendix or AFP setup weighs compared to the carb.

SDS- single ECU fuel and spark is around 15.5 lbs., dual ECU setup around 17 lbs. Can also save 1 pound with the lightweight flywheel, around 2 with a flywheel with no belt groove, another pound by removing the mag drive gears. There would be a slightly heavier Duplex fuel selector and return lines but these wouldn't weigh much more than the boost pump and lines.

Looks like you'd come out around 2-6 pounds lighter with the EFI depending on the system chosen and options to reduce weight.
 
Cooling airpath still ok with lightweight flywheel?

Hello Ross

Do you have any information about cooling, when using your lightweight flywheel?

I remember that Dan Horton made seal that where sealing at the conical face of the flywheel, this to stop there airflow out at the front side of the cowling. With the opening on your flywheel this is disturbed ...

Any possibity to let a this wall there on the lightening holes?

I will look for the thread of DanH.
 
I imagine Ross could have one made without the big lightening holes in the conical section, but a lot of the weight savings would be gone. If running a prop extension, the foam seal approach seems to work well.

Propshaft%20Seal1.JPG


Propshaft%20Seal2.JPG


Cowl%20Sealing%20Surface.jpg
 
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As Dan said, we could leave the large lightening holes out of the machining process to seal things up but it would be only a few ounces lighter than the stock one. The stock one might be a better bet although be aware that new Lycoming engines are coming with flywheels which lack the 12 tooling holes to use our drilling jig for the magnets (also used for prop balancing). Also we found out last week that some Lyc 540s are coming with a dual sheave flywheel which isn't suitable for mounting our magnets either. Further, be aware that the Sky Dynamics ones also can't mount our magnets.
 
Thanks for the weight analysis. Looks like the SDS system does not have a weight penalty, but has significant benefits. However, with all of the flywheel variants in the market, looks like there will be some confusion.

Good stuff.
 
Thanks for the weight analysis. Looks like the SDS system does not have a weight penalty, but has significant benefits. However, with all of the flywheel variants in the market, looks like there will be some confusion.

Good stuff.

Looks like pre-2017 factory Lyc flywheels should be fine and the SDS ones.
 
There are a large number of RV-10s built by a commercial builder in Brazil and others in South America. Almost all of these have air conditioning as an option. As a result, when you order a Lyc from Vans it most likely be one with twin belts on the flywheel to support the AC compressor. They do not work with Lightspeed ignition or SDS.


Made a special request when I got my motor from Vans to have the single belt flywheel and that is the way it came. I would advise talking to Vans before ordering to be sure you will get a single belt type unless you want the second. I would have gone with Ross's metal art flywheel if it had been around.

I got my motor about three years ago and things may have changed but it is a good question to ask when ordering.
 
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