Wednesday July 19, 2006

Very hazy day. Severe weather developed late in the day yesterday, drenching areas around Indianapolis and dropping nickel size hail. We were spared. This morning the clouds were gone, but the heat, humidity and air pollution have combined to create thick haze.

FOX will be televising the take-off tomorrow morning, live, on the local affiliate's morning show. It means lifting off 45 minutes later than I'd planned, but the publicity is worth it. The flight to Dayton (MGY) is about 110 miles, and if the weather Gurus are correct, when the breeze starts it should be from the SSW. Since my course is about 100 degrees, I may have a bit of help, but that will be canceled out by the crabbing component. I'm hoping the flight will last about 4 hours.

I'm very pleased that almost everyone I'm speaking with now acknowledges the advantages of the HKS engine over the Rotax 582. (And that means I've been speaking with a lot of envious Rotax users!) If you need a 912 for the power, then granted, the HKS won't do the job. But if a 582 will suffice, the HKS is a better choice.

Why? Let me list a few reasons:

1. The 582 TBO is 300 hours. Each rebuild costs at least $2,500. That means that at 900 hours a 582 owner has spent $7,500 on the rebuilds. Just the rebuilds on a 582 runs $8.33 per operating hour.
   
   The TBO on the HKS is 800 hours. The rebuild costs about $800. The HKS rebuild costs $1.00 per operating hour.
   
   Therefore in terms of just the rebuild cost, the HKS costs $7.33 per hour less to operate.
   
   
2. Fuel cost: Although fuel burn rates vary widely, it's fairly well acknowledged that a 582 which burns an average of 4 gallons an hour is considered fairly efficient. The burn rate of Voyager's HKS (and don't forget that Voyager is weighted down with about 100 pounds of extra gee-gaws and doo-dads added for the cross-country trip and for show) is less than 3 gallons an hour. (I've experienced legs that were only 2.8 gallons an hour.)
   
   A one gallon an hour burn rate differential translates into at least $2.75 an hour savings.
   
   
3. I don't remember any more how much two stroke oil an hour the 582 burns. It's not a huge amount, but over hundreds of hours it's not insignificant. This is an additional cost, as the HKS is a four stroke and only needs an oil change (about 3 quarts) every 50 hours.
   
   
4. Four stroke reliability. It's a cliche, but it's true: A two stroke engine will run perfectly as long as every part operates perfectly. A four stroke engine will continue to operate well with quite a few parts not operating correctly. (There's a reason cars and GA aircraft operate on 4 strokes.)
   
   So... ignoring the cost of the two stroke oil, a 582 costs at least $10 per hour more to operate than an HKS. Over 900 hours that's at least $9,000. Throw in the reliability inherent in four stroke engines, and I think the case is fairly well made from an operating cost standpoint.

Performance-wise, having flown a Destiny with a 582 for 3 years, I can't discern any real difference. The HKS has a 3.27 reduction, and swings a 72 inch prop. Although I've not measured the thrust, I can't ignore the fact that on this trip I've lifted off, fully topped with 18 gallons of fuel, from airstrips that were over 7,000 msl, and (at 6 in the morning) already had density altitudes of over 9,000 feet. The highest density altitude in which the HKS pushed me along was about 13,500. It's hard to knock that kind of performance.

I'm sure there are those who will have a different opinion on the subject than I, but those are my thoughts.