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Thread: A four-stroke

  1. #1
    zaitcev's Avatar
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    A four-stroke

    If you were to re-engine a Kolb Firestar with a 4-stroke engine, what would you do?

    Firestar is a quasi-ultralight that does not quite qualify for the Part 103 limits and is usually available as pre-owned EX-AB or grandfathered E-LSA. Kolb's heavier 2-seaters use the Rotax 912, but I'm generally curious about something below 50 hp.

    I just read on his blog that Jim Wiebe tested a Belite with 1/2 WV by Hummel. To get there within the Part 103 weight, he had to do a major rework by switching to an all-aluminum construction, so I do not expect to see many ultralights under 4-stroke power. Still, it is very intriguing... We have a regular fly-in that I often attend in a rental that is about 2.5 hours away if you make 60 mph. I see many benefits from increased range and larger TBO, just wondering what the costs are.

  2. #2
    You might want to take a look at the largest of the 1/2 VW models from www.hummelengines.com at 45 hp and 84 lbs, but you will be giving up thrust and adding weight compared to something like a Rotax 503. Still, the pleasant sound and lower fuel consumption might be worth it.
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  3. #3
    Quote Originally Posted by zaitcev View Post
    If you were to re-engine a Kolb Firestar with a 4-stroke engine, what would you do?

    Firestar is a quasi-ultralight that does not quite qualify for the Part 103 limits and is usually available as pre-owned EX-AB or grandfathered E-LSA. Kolb's heavier 2-seaters use the Rotax 912, but I'm generally curious about something below 50 hp.

    I just read on his blog that Jim Wiebe tested a Belite with 1/2 WV by Hummel. To get there within the Part 103 weight, he had to do a major rework by switching to an all-aluminum construction, so I do not expect to see many ultralights under 4-stroke power. Still, it is very intriguing... We have a regular fly-in that I often attend in a rental that is about 2.5 hours away if you make 60 mph. I see many benefits from increased range and larger TBO, just wondering what the costs are.
    This might get you interested in a four-stroke:

    http://eagleXL-58.com

    And XL-58's Youtube channel:

    http://www.youtube.com/user/EagleXL58?feature=mhee

    The Casler 45 is about 87lbs with aluminum cylinders. Definitely makes for a neat sounding UL with low fuel consumption.

    By the way, the Legal Eagle with 1/2 VW can meet Part 103 if built strictly to plans. No parachute allowance needed.
    Last edited by Sam Buchanan; 02-02-2013 at 11:06 AM.
    Sam Buchanan
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  4. #4
    zaitcev's Avatar
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    Thanks for the information. I am getting the picture that Hummel is #1 for this kind of thing. I was just wondering if anything else is worth considering. I saw ads at Barnstormers for things like Gull with HKS 4-stroke, but I don't know anything about HKS' track record. Way back then, some folks were unhappy with their parts service. Also, I'm intrigued by Valley's Generac-based engine with belt drive. Their complete weight is 120 lbs (radiator, starter, etc. - everything is included). Hummel's analog is 106 lbs, but apparently that's without accessories. Valley unit is a single ignition type, as I understand.

  5. #5

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    Valley unit is air cooled, thus has no radiator. Listed weight does include the re-drive though.

    Here's a couple in action on Airdrome replicas:

    http://www.youtube.com/watch?v=2pCk9gdr5dg

    http://www.youtube.com/watch?v=KZN-rGdY518

    Sure sounds a hell of a lot better than a chainsaw motor!!
    Last edited by Bill Ladd; 02-03-2013 at 02:58 PM.

  6. #6
    zaitcev's Avatar
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    Bill, I meant the oil radiator. On their own airframe, BYF, it's attached to the bottom of the motor mount.

  7. #7

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    I'd go with any of the 1/2 VW engines. I've owned and flown a Fisher 505 with one on it and was very impressed by the power. Also, the sound and the fuel consumption can't be beat! Check out the Legal Eagle site, great info there.

  8. #8

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    I like the Verner two cylinder, four stroke engine. http://www.vernermotor.com/ Compare to the HKS.

  9. #9
    [QUOTE=zaitcev;26979]If you were to re-engine a Kolb Firestar with a 4-stroke engine, what would you do?

    Firestar is a quasi-ultralight that does not quite qualify for the Part 103 limits....

    I've owned two early (lighter) Firestars. The lightest one weighed 318 lbs with no frills other than an extra 5 gallon tank, which could not weigh more than 5 lbs, max. This airplane had a Rotax 377 2-stroke engine and IVO prop. You might be able to save a little bit with a wood prop but to get an early Firestar down to UL weight limit of 254 lbs is probably an impossible task unless you go to a single cylinder engine, because you will have to save over 50 lbs compared to what mine weighed and it was as light a Firestar I've ever seen. Good luck with your efforts. Firestars are great airplanes.

    Thom in Buffalo

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