jindoguy(at)gmail.com
Guest
|
 Posted: Tue Mar 13, 2007 9:54 am Post subject: HKS data points |
 |
|
Finally forced myself to take a day and get the trike up for its first flight. I realize this is the Kolb list but since Dave in Hawaii is putting an HKS on a Firestar I decided reporting on engine perfomance wouldn't be a stretch.
There are two versions of the HKS gearbox, Dave has the 2.58 to 1, I have the 3.47 to 1.
The engine is mounted on a Northwing Apache Sport trike with a 19M single surface wing. For those of you unfamiliar with flex wing aircraft, this combination can be characterized as a boat. Heck, Vne is 55. I found myself channeling Sammy Hagar while flying, but that's an aside of no consequence.
The empty weight of the trike and my 582 powered Mk 3 are very close as are the propellor sizes (68" and 66" respectively) and gear box ratios (the C gearbox on the Mk3 is 4.00 to 1). After the first two landings over the course of the first hour of flight time, I began to relax and enjoy flying the trike and make some comparison to the feel of the trike and the Mk3.
The first thing I noticed was how similar the acceleration of the Mk3 and the trike are, take off runs were roughly the same length and initial climb out of about 500 fpm is very close. I have a Warp Drive 3 blade on the Mk 3 set so that I get 6200 RPM in climb, which I think is a little steep because I see Vne before I see 6500 in level flight. Now, many of you have already brought to my attention that my ASI may be a bit optimistic, so take those numbers with a grain of salt. I only took the HKS and its 4 blade Power Fin to 5800 RPM for one take off and used 5500 for the others. I used 5100 to 5200 RPM for climb out after the rotation adjustment (if you think the high thrust line of the Kolb gives a power pitch coupling, it's virtually unnoticeable compared to the trike) and that's where I got the 500 fpm climb. Some of the inability to reach full rated take off power for the HKS may be as much too big a shoe size as too much prop pitch as the trike has a foot throttle as well as a hand throttle and I used the foot throttle exclusively for take off and initial climb. I'll have to do some more checking here.
The next thing that became apparent is the power curve on the HKS is essentially flat, just as the literature describes it. The 582 has always stuck me as peaky in its power delivery. 4000 RPM is about the lower limit of its usable power in level flight and even with David Clark's on it is loud, at that RPM or any other. At that same RPM, the HKS is purring quite nicely even though the only hearing protection I had was a Shoei full face motor cycle helmet, and the trike could manage a nice 150 to 200 fpm cruise climb. Usable power for level flight extended down to 3500 RPM. If you consider the differing gearbox ratios, prop RPM comparisons betwen the two engines are fairly similar, too.
So there you have it, two data points, both pretty subjective. I can tell you this, I'm leaning ever more to an HKS on my next Kolb. Now if I could just decide between the Kolbra and the Extra.
--
Rick Girard
"Ya'll drop on in"
takes on a whole new meaning
when you live at the airport. [quote][b]
| | - The Matronics Kolb-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kolb-List |
|
|
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
