outside the box; "regulations? We don't need no stinken' regulations"

[simey_binker]

as the title suggests; I am four of the five things listed below:

Tired, as it is 3am presently
Typing this message out on my iPhone
Tripping out on the Beatles, Stawberry Fields
Am a tremendous UL newb
Am a gigantic purple elephant

I'll let you decide which four are true of me

Long story short: I'm a gradute of mechanical engineering at queens university; and since first year I've been hooked on the idea of building an UL. Please note that I know juuuust enough to hurt myself badly. Just enough of a limited budget to "work around" things to save some coin. That having been said, I'll be saying some dumb things for a while because I don't think conventionally, AND I'm a newb.

On with the question regarding engines; what's all the fuss about the rotax 912s etc? Does scarcity drive up the price? Because if these engines aren't plated in gold, their mechanical use is NOT worth the price tag IMO. Regardless, if someone were to build a homebuilt, what engines can/can't they use? Hypothetically, other than weight restrictions, what stops me from dumping in a v8 twin turbo? Does transport canada restrict the engines to dual spark? Only "aircraft" engines? Because I could think of a couple other platforms that would have better weight to ratio, and IMO, a higher reliability.

Blah blah - go nice on me guys
Thanks
Sim

[simey_binker]

woooow - this forum is sloooow - we need some heavily committed individuals to get some chatter in here. I've actually migrated over from turbobricks.com; and they have a ludicrous turnover for posts. I guess you guys are all out busy flying.

anyhow, while you're all pondering why we pay thousands for Austrian aviation (the Rotax engines); think about this: the Honduh F4i engine weighs the same as the Rotax 912s (58 kg), and I believe I can pull MORE power out of it. it's fuel injected, and potentially can even have a turbo or super charger fitted to it. actually, the F4i could be potentially lighter if the gearbox was modified for single speed (instead of stock 6-speed intended for motorbikes).

ebay has F4i engines selling for between $600 and $1000. some Formula SAE (fsae.com) cars using the F4i engine pull 100 HP out of them... WITH AN AIR RESTRICTOR.

the question is; why pay $17500 for a rotax 912? seriously, no 100HP engine should sell for that much. again, are they gold-plated?

thanks,
Sim

[simey_binker]

the polaris 600CFI, and Bombardier 800SDI... 120-160HP; direct/semi-direct injection, altitude compensating up to 13000 ft. less than $2000?

why the magical 912?

Sim

[simey_binker]

haha - this is driving me nuts; I could spend $17 500 on a 100HP Rotax engine... or buy a 350HP, AWD, 2002 Subaru STi (the ENTIRE vehicle) with a boat-load of modifications - basically the greatest car on the road...

shame.

I need some answers here.

Sim

[Matthew Roung]

Probably because people keep buying them. Personally, if I wanted 100hp 4 stroke in a plane I would not buy a 912, or a Jabiru. A motorcycle or watercraft engine would do, but I don't mind tinkering. Too many just plunk down the $$ for something to bolt in. I have a 912s in a Tornado, and a Soobie in my Buzzard, I feel just as happy behind or in front of either. Building a Bearhawk, going Subaru power for sure!
-Matt

[Matthew Roung]

Gotta remember most in aviation are a real conservative bunch, in other words, if it isn't "made for aircraft" and a whole pile of money, it isn't any good. Takes a while for new ideas to catch on
-Matt

[Matthew Roung]

Honduh F4i engine weighs the same as the Rotax 912s (58 kg), and I believe I can pull MORE power out of it. it's fuel injected, and potentially can even have a turbo or super charger fitted to it. actually, the F4i could be potentially lighter if the gearbox was modified for single speed (instead of stock 6-speed intended for motorbikes).

ebay has F4i engines selling for between $600 and $1000. some Formula SAE (fsae.com) cars using the F4i engine pull 100 HP out of them... WITH AN AIR RESTRICTOR.

the question is; why pay $17500 for a rotax 912? seriously, no 100HP engine should sell for that much. again, are they gold-plated?

thanks,
Sim

I Honda's PWC, they use a modified F4i engine I think, with turbo, around 170hp
-Matt

[Dyceman]

Simey says

"Does transport canada restrict the engines to dual spark? Only "aircraft" engines? Because I could think of a couple other platforms that would have better weight to ratio, and IMO, a higher reliability."

==================================

Transport only cares what engine you bolt to your airplane under the following conditions:

1) Is it a certified airplane
2) Is it and AULA (Advanced Ultralight)

If you are building under the amateur built rules, or building/assembling a BULA (Basic Ultralight), you can pretty much bolt whatever engine to the airframe you want - since you are the manufacturer.

For certified and AULA, you are not the manufacturer, and you can ONLY use the engines (and in some cases, engine singular) that the manufacturer has approved for THEIR airplane. For AULAs, TC list of approved models also lists the approved engines -- most of which are Rotax and Jab, but with a smattering of others.

For example, although a 912s or various auto-conversions would probably be enough power for a Cessna 150 (weight and balance issues not withstanding, particulary balance) you can't use these engines in place of the contenental O-200 (C-150) or Lycoming O-235 (C-152) unless you had permission from Cessna. And the manufacturer would not grant permission unless they took on the task of testing this configuration first and applying for certification using that poweplant. They're not going to go to all the trouble just for you.

[Matak]

Shame. It's too bad TC doesn't approve a 'list of acceptable powerplants'. That would give us some flexibility. It would also open up competition and therefore make the engines more affordable. Maybe someday.

[Dyceman]

Matak,

Shame. It's too bad TC doesn't approve a 'list of acceptable powerplants'. That would give us some flexibility. It would also open up competition and therefore make the engines more affordable. Maybe someday.

Don't forget - if building an Amateur-built plane or a BULA, you can use whatever engine you want. Use an old outboard motor if you think it will work. It's up to you since you are the manufacturer. It's only when you get into "certified" airplanes, and to some extent, AULA's, that your choices are limited.

It’s not really so much that TC “approves” individual powerplants and therefore could make s “list” of acceptable units that one can use on any old airplane. Every airplane configuration is different, so one engine may or may not work well on a different airplane. There are weight and balance issues to consider, cooling issues requiring unique cowling designs for different airplanes, and so on. That’s why TC can’t just make a list of “approved” engines thus letting you have the freedom to just pick from the list and bolt them to your airframe.

The airplane manufacturer makes the decision on what engine to use (and test) with their design. In fact, airplane manufactures tend to make their engine choice very early in the design phase and design the plane around the engine. That’s how important it is. It’s the whole completed package (airplane and engine) that ultimately gets certified by TC. Once certified, you (the aircraft owner) can’t swap the engine out with something different, since that is the only powerplant listed on the airplanes type certificate (unless the manufacturer has tested and certified the airplane for other engines).

In order to be used on certified aircraft, engine manufactures have to run their engines through a series of lengthy and costly tests, including destructive testing. I don’t know all the details of this topic, but once an engine has received it’s certificate, it is then in the aircraft manufacturers ballpark to choose which of the available certificated engines to use on their airplane. The aircraft manufacturer then puts their airplane/engine package through a variety of expensive tests prior to seeking certification of the airplane.

For example: there is a certificated version of the Rotax 912 and a non-certificated version. Both are identical engines off the same assembly line, but the certificated units are put through more tests prior to shipping (and therefore more expensive). The non-certificated version cannot be used in a certified airplane. Only homebuilts and ULs.

Another example: the Continental O-200 (used in the C-150, plus others, including many homebuilts) is an excellent, certificated aircraft engine. But that does not mean you could simply bolt it onto any airframe. In order to use this “approved” engine on an airframe it wasn’t designed around, you may have to make extensive modifications to the engine mount (move it forward or backward for balance considerations), modify the cowling to facilitate appropriate and adequate airflow, plus who knows what else. TC can’t be sure if the resulting plane will fly safely, so you, or the manufacturer, must take on the task of testing all this prior to seeking certification. Even if it’s a home-built, you need to complete and demonstrate 25 trouble-free flying hours, and do***ent the results of a variety of tests before your “certificate” is actually granted.

It’s complicated, but it’s supposed to be (they claim) for everyone’s safety. The certification process is one of the major reasons why airplanes (and engines) are so expensive. Plus the fact that they have a very small consumer base. Unlike boats, motorcycles and ATVs – which have a huge consumer base, and by comparison, virtually no certification requirements; but are equally, if not more, deadly to their operators or innocent bystanders.

Go figure . . . but that’s a whole other topic :)

[simey_binker]

wow - when it rains, it pours. good to have you guys around. where is everyone these days? I think this forum has tremendous potential, but I have no idea where people are these days.

maybe it's the lack of new and creative ideas that has people bored. well, I'm all for some nutty ideas. hopefully I won't find myself 10 feet in a ditch in the middle of some farmer's field.

thanks for the info boys.

alright, with so many different licenses, and so many different types of crafts, it's easy to get confused. I've done a LOT of research, and I think I have my answers, but I'm going to bounce the question off you guys to see if you have the same answer:

I want to build my own craft. I want it to be two seater; and the second person doesn't have to be a pilot.

I'm thinking I'm going to have to go for a homebuilt/experimental craft, with a recreational aircraft license. sound like a good combo? or am I just setting myself up for fail. anyone else go down this path?

Sim

[Matak]

Wow, I never realized that there was that much testing and rigmarole that went into aircraft certification. It was interesting to learn that an aircraft designer would place the powerplant among their first considerations. It's a wonder we have the spectrum of aircraft that we do have.

BTW Dale, thanks for taking the time & effort. Much appreciated!

[Dyceman]

Matak - thank you.

. . . and I'm no expert by any means, just read alot about this stuff (and been flying 12+ years). If anyone finds error in anything I've posted, I won't be offended to hear it.

Powerplant selection is typically one of the first things an aircraft designer takes into account when engineering their design because weight, balance, and power are key design elements in aircrat and each powerplant is a little different. These things can be difficult to re-engineer late in the game. For engines of equal weight and horsepower, it may not be that difficult a swap. Some airframe changes (cowling for example) may be needed, but maybe not too much.

That being said, a powerplant swap does happen even for big league manufacturers. Sometimes more for marketing/economic reasons than performance.

Example: the new Cessan Skycatcher (the new C-162 SLA) was originally designed for the Rotax 912s (100hp) and was built and test flown and rolled out with this engine. BUT due to distributer concerns over the accpetance of this "experimental" engine, Cessna opted to go with the traditional Continental O-200 engine. Same horsepower but WAY more weight. The resulting reduction in usefull load of the C-162 is considerable in my opinion and has been much maligned by other aviation observers. They probably had to make some other tweaks to make the balance work out as well.

I forget the numbers off hand, but with full fuel, the C-162 has a pilot/passenger load of about 340 pounds. Not that great.


Simy -- I think you are probably on the right track. Many hundreds have successfully gone down the same road in Canada. Thousands elsewhere. You could still conisder AULA, since many of these still require considerable building on your part. The downside is you can't make any modifications or changes later.

[simey_binker]

hm - alright - I like the vibe in this thread. I'd start up a new thread for this question; but it seems like this one is quite ducky.

I forget if I've mentioned this (there's long intervals when I check this site), but I'm a recent graduate of Mechanical Engineering. I've found there's two types of engineers; those with street smarts, and those with book smarts. obvious, I know. and this is the case for ANYONE - pertaining to aircraft construction; some mechanics are more book smart, but most mechanics are known to be street smart.

I happen to be more street smart, but with the engineering degree, I've been forced to be "book smart". I plan on building my own ultralight; and I have a choice to go either book, or street smart. the difficulty is that I lack the street smart for ultralight construction presently.

now, I could sit down with several computational fluid flow programs, text books, PHD journals, and modeling software, and try to build the designs that way. it would take months - probably years, to even get close to modeling it the correct way. OR, I could learn from all of you guys, and bust out a napkin and calculator and have the general aircraft designed in a few weeks. I like the latter idea. I can always tune it as I go.

all to say, do you guys know of any "street smart, backyard building" websites with some quick and easy rules to ultralight construction? balance points etc? I have a java program to calculate lift from wing design/speed - but what else is there?

I'm going for 2 seater, tandem, ~150 hp engine, I'd like to have bottom-mounted (or mid-frame) wings, built of aluminum/composite (carbon/fibreglass/nomex, aluminum honeybomb and/or balsa core), and amphibious.

I'm weighing out whether or not I want to sacrifice fun-ness, and do a top-mounted wing with a floatable body (for simplicity), with a pusher engine in the rear; or have bottom-mounted wings, engine in front, with pontoons. now... what I was thinking... was retractable pontoons... a discussion for later.

anyhow - I'm looking for sources for good "DIY ultralight" sites. I know I'm playing with fire here - it's like asking for "DIY space shuttle sites" (you just don't do that), but I'm thinking that more ultralights have been made, than space shuttles. there have been people who have gone before me. and please keep in mind I'm an engineer; so don't worry about "getting too technical", or that you're giving a gun to a child.

thanks guys,
Sim

[Dyceman]

Hey there Simy,

150 hp seems like a lot of muscle for an ultralight. Remember, to keep your project in the UL category, it can't gross more than 1,200 pounds. That means you want the empty weight to be not too much more than 700 pounds in order to have some decent useflull load. I guess it might be possible with a 150 hp engine. I've never heard of an AULA or BULA with that much HP.

You'll have to go BULA if builing your own ultralight from scratch and your own design.

It sounds like you might be looking more towards the amateur built category. Maximum gross there is 5,000 pounds

EAA is as good a place to start as anything. It's a huge topic.

http://www.eaa.org/homebuilders/

There are plans available for literally hundreds of different home-build designs. You could find something you like and make "modifications" to suit you and within your engineering abilities. Or, you could start with a clean piece of paper and do your own design. Of maybe look at several designs and "amalgamate" a few things into a project.

Not something I would/could ever do. But if your engineering skills are good, then I gues anything's possible.

Not sure if that is much help. If I think of anything else - I'll pass it along.

[simey_binker]

aaaw - yeah - this is great info! and so quick too! I'm used to massive forums with quick turnovers; in September and October, this place was dead. good to have a few good men around.

well, as stated earlier in the discussion, I'm thinking I'll use something like a Honduh F4i instead of the costly 912s. and I'm thinking I can pull at least 100 out of it; that's been done with an air restrictor (for racing) on it. so I can probably pull 150; and as suggested, some have pulled upwards of 170HP out of these engines. awesome? you know it. and they're the same weight, maybe less, than the 912s. even still, I knew the homebuild could have upto 5000lbs - so weight isn't too much of an issue. however, I'm planning on keeping it light.

better yet; check this out:

http://www.h1v8.com/page/page/1562068.htm
http://www.h1v8.com/f/dyno_mpeg_compressed.mpg

heh heh - could you imagine THAT in an ultralight/homebuild?

Sim