Rotary Engines

[Kirk Feldkamp]

While the topic of diesels is out there, I also wanted to toss some of the new small rotaries into the ring. The Axiro XR 50 (http://www.woelfle-engineering.com/Produkte/produkte_XR50rotaryengine_en.html) is a bad little mammajamma. Pat, any chance the rules committee will get away from the pistons-only requirement anytime soon? I figure it's all part of the trade offs... sure it has a high power density, is four-stroke, and electric start... but fuel consumption (lower BSFC) and passing sound would be the challenge! It's also only a single speed clutch setup, which brings in a whole other set of interesting trade offs! Do most drivers learn faster and run quicker on average without the transmission (my guess is yes)? I think this alone would inherently bring much closer competition into the events. Would teams need to go to the effort of designing and building their own transmissions or transaxles? I personally don't think so, but it's an interesting option that opens up a wide range of mechanical design opportunities. These engines are extremely reliable in karts both in the US and UK, and surely would be in FSAE cars too. Dare I say more reliable than the Aprilias will ever be? Haha.

I've been thinking about putting one of these into one of our old single cylinder cars for some time now. I think it'd be a hoot as a "TAG" FSAE concept!

-Kirk

[PatClarke]

Kirk,
The Axiro is a kart engine, hence the clutch/transmission issue.

I guess nothing will ever happen until someone writes to the Rules Committee asking that the rotary prohibition be lifted. Assuming the response was not a flat 'No', the matter would be discussed by the Committee, who would base their decision on the information available or the argument put up by the proposer.

My thoughts? I reckon you would have as much success getting a nuclear reactor approved =]

Cheers

Pat

[Kirk Feldkamp]

So you're saying there's a chance!? Haha.

Given my past experiences with trying to get the rules committee to understand what I believed to be a fairly straightforward argument about the position of the throttle body within the system... yeah, I realize it's a long shot. You commented that it's a kart engine, which I definitely understand. Is there something about a "kart engine" specifically that I should be aware of from a rules proposal standpoint? I mean, it's still a 4-stroke after all. I ran into a bunch of roadblocks on the throttle body proposal that, in my opinion, were incorrect, unfounded, or outdated assumptions. It would be interesting to hear about any previous discussions that you've been privy to in reference to this.

Worst case, I get to have fun with my own car on my own terms! Not that bad to a deal.

[Mumpitz]

As a die hard wankel fanatic myself I wish there was more enthusiasm for the spinning doritos in Formula SAE. The are still very relevant to the auto industry. Mazda is bringing it back despite axing the RX8, a few companies are looking to use rotary powered range extenders for their EVs.
http://green.autoblog.com/2010...y-ev-range-extender/ (http://green.autoblog.com/2010/07/16/avl-introduces-its-own-wankel-rotary-ev-range-extender/)

Many UAVs take advantage of their weight/size/power.
http://www.militaryfactory.com....asp?aircraft_id=824 (http://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=824)

Generators? yep them too, for being quiet and fuel efficient of all things! I guess they do not run a bridge port with a racing beat header on this generator...
http://www.freedom-motors.com/
Going way out to left field with the future of rotary engines, I don't even know where to begin with this one.
http://bsac.berkeley.edu/group...d/mems_reps/home.htm (http://bsac.berkeley.edu/groups/bmad/mems_reps/home.htm)

In short I agree with Kirk, it's a shame if they aren't at least considered.
But hey as they say on the interwebs
http://images.piccsy.com/cache/images/5679-d4f5e7-500-357.jpg

[Kirk Feldkamp]

As with any rules changes in FSAE, it won't ever happen without at least an external proposal to the committee. They're definitely not sitting around coming up with rule changes out of the blue, except for perhaps in the area of safety.

I'm hardly a diehard Wankel fan, but one of the coolest things I've seen in the past couple years was the use of Wankels for hydrogen combustion. They're apparently very useful for this because of their lack of overlap (as in a traditional piston engine) and also their very long combustion "stroke". Apparently the overlap period causes some pretty big issues with backfires into the intake. BigBird can testify to the challenges of doing hydrogen combustion with a "regular" engine. The relatively long combustion period of the Wankels was actually what the article attributed the apparently clean and complete combustion to. Like they also mention in the article you linked to about the AVL unit, the power density is also fantastic. Pretty neat if you ask me.

[nowhere fast]

Originally posted by Kirk Feldkamp:
I mean, it's still a 4-stroke after all.

How do you differentiate between 4 and (I'm assuming) 2 strokes? Rotaries complete one full cycle for each revolution of the output shaft, just like a 2-stroke.
I think if rotaries were to be allowed then 2-strokes should be too, they still have pistons after all.

[AxelRipper]

While we're on the topic of allowing things that aren't allowed in FSAE, any chance we could run Isobutanol (see: Dyson Mazda Lola) or Methanol (M10 is standard in China, and there's talk of M50)? How about turbos before the restrictor?

4 wheels in a straight line?

[PatClarke]

Turbos before the restrictor??

Dream on AR http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif http://fsae.com/groupee_common/emoticons/icon_smile.gif

Other fuels?

Probably not unless there is a very good argument to do so. The main reason being logistics

When I was tech director for the Aussie competition, I did have an enquiry about a diamond car, two wheels in line and two outriggers. Apparantly, this setup was specified by a potential sponsor!

Apart from the obvious point about who was actually designing this car, it came to nothing and the team turned up at the competition with a very conservative design,,, and no big sponsor http://fsae.com/groupee_common/emoticons/icon_smile.gif

Pat

[Michael Royce]

Whenever the topic of other engines (other than 4 stroke piston) and fuels (other than gasoline or E-85 in the USA) comes up, and it does every 2-3 years, the Rules Committee has to look at the "benefits" versus the complications.

The first and main question they ask is "will making this change improve the educational benefit to the students from the programme and the competition?" If the answer to that question is "No", and it does not improve safety, then the likelihood of making the change is slim to none.

As far as allowing diesels, rotaries or 2 strokes, teams very seldom get into the internals of the engines, so apart from different detailed packaging and tuning requirements, what educational benefit would it bring to the students?

2 strokes have not been allowed for many years for 2 reasons. First from an emissions point of view, across the complete spectrum they are being phased out due to having a hard time meeting emissions standards. So they are a dying breed. Secondly, from a workers' point of view, they are a "pain in the ear". Anyone working close to F440/500s or F125 shifter karts will attest to that.

Rotaries - again why? Coming up with an equivalency to 610 ccs is problematic, as there is no recognized consensus on the correct formula. And trying to measure the displacement of a rotary..., I, for one would not want to do that, and I don't think a team would appreciate having to tear the whole engine apart at the competition so a displacement check could be made!

Diesels - Pat has covered that one.

So, as long as there are sufficient different engine options, why make a change?

Different fuels - why? What educational benefit would it bring? Providing 3 fuels at the US competitions is complicated enough. Teams in some places have enough problems getting E85! We used to have M85 in the USA, but it went out of favour when the DOE removed the prize money for it, and we added E85 when the US industry started making cars to use it. And it is available in some parts of the USA.

Like Pat, I cannot see changes, other than those already in at Formula Hybrid (diesel) and F Student.

[Whis]

Oh man, I can't believe I'm gonna do this but I have to disagree with you a point, Mr. Royce. I'm not quite sure 2-strokes are a dying breed, there is a lot of research into direct injection 2 strokes. I don't think the potential for a learning improvement can be seen here however nor an improvement for performance because cc for cc, most high performance 4 strokes meet the power levels of most high performance 2 strokes. So, I guess I'll just cede the point anyways. Oh well...

[Adambomb]

My $0.02...

Regarding direct injection 2-strokes, what I saw during my co-op at Mercury Marine in 2006 was that, as has been mentioned, the "dirty 2-strokes" are going away, and if I remember right they're probably out already (haven't looked in a while). I'm not familiar with how the emissions of the DI 2-strokes compared, but the effort at that time was focused more on their Verado supercharged 4-strokes. There wasn't a lot of development with the Optimax DI 2-strokes, and they were replaced by the Verados as the flagship engines. I also know that while oil consumption for the Optis was quite low for a two stroke, there was still oil consumption, which I can't imagine would be great from an emissions standpoint. Also worth noting, I don't recall DI 2-strokes coming out in anything outside of outboard boat motors and snowmobiles.

Now that being said, strategically speaking, a two-stroke would make a lot of sense with a lightweight single cylinder car. Not to say that the single cars need the help, but I can easily imagine a 350cc two stroke car coming in at under 300 lbs (without compromises to performance) and doing very well. However, a DI two-stroke is not likely lighter or simpler than a modern 4-stroke...

One last argument for a two-stroke, taking into consideration that there are design points to be had for something that is "like a race car," never mind the marketing potential, how cool is this:

378 hp 2-stroke 3.3L V6 (http://www.youtube.com/watch?NR=1&v=o9VbLczn9kc)

Bear in mind that engine weighs under 200 lb...

[Z]

Kirk, Sorry for hijacking thread, but...

2-stroke diesels are the most powerful and fuel efficient IC engines on the planet. Just pop the bonnet on any big ship...

As for education, I think it is the SAE, and car industry in general, that needs the learning. Some open minded students might be able to do the teaching, but I guess the old dogs don't want to learn any new tricks. http://fsae.com/groupee_common/emoticons/icon_frown.gif

Z

[RollingCamel]

Sorry to derail the thread a bit, but in formula electric or hybrid are electromechanical systems like energy storing flywheels possible?

[Michael Royce]

RollingCamel,
Flywheels in FSAE, Formula Hybrid or Formula Student??!! Having been directly involved (in charge of the dyno development of the powertrain) in Chrysler's ill fated Patriot Le Mans hybrid programme, I have enough safety concerns about flywheels from people like Flybrid and Williams without having to worry about student designed units!! We, the organizers, have enough challenges dealing with the electric and hybrid vehicles with several hundred volts on board.

A couple of years ago, the SAE's University Programs Committee, which oversees all the SAE's Collegiate Design Series competitions, voted that the CDS were for "education not invention". So leave it up to Flybrid and friends to play with them for a few years. And again, what would be the educational benefit to the students of allowing flywheels, with all the potential problems they could bring?

Once energy storing flywheels in automobiles are a mature technology, it will be time to consider allowing them in FSAE or Formula Hybrid.

[RollingCamel]

My cousin in Texas A&M Qatar with his research team were researching flywheels. Talking a test cell engineering company they told him about an incident of a flywheel test failure which sent projectiles through a 20mm steel casing, large cement wall and building walls to kill 2 ppl outside the facility....

On the other hand, Porsche did it, but I totally understand your point.