Air bike Tandem- getting started

[DAB677]

I have a single-place Air Bike that I'm flying out of Ramona Airport. I'd be happy to show you the aircraft and help you any way I can.

David

[HAPPYDAN]

I have a single-place Air Bike that I'm flying out of Ramona Airport. I'd be happy to show you the aircraft and help you any way I can.

David

I have also kicked around the idea of going "ultralight". But I have heard conflicting reports regarding the reliability of 2-stroke aircraft engines. I would like to get your opinion also, especially regarding the Hirth engines.

[Norman Langlois]

The 2 stroke reputation is from and earlier time when experimentation was without data.That Data gathered from all the bad experience and good , has its roots in today's engines and range of performance. I respect the past and would use the tried and rated . I have been flying with one of the lightest weight to power ratios a 440 Kawasaki . there are many of them out there still in use. If I were going to fly and use a new engine it would be the new F33 Hirth 50 HP electric start and the total weight is only a few lbs over my hand pull Kawasaki system.
There are very few Ultra light engine failures these days. The news is far more disturbing for GA and LSA engine failure , This year has me wondering why.

[HAPPYDAN]

Thanks, Norm. I have considerable experience with (older) 2-stroke motorcycle engines (Suzuki and Kawasaki), and was perplexed by anecdotes of seizures and in-flight failures of those designed for aircraft. It's nice to hear from someone with actual experience.

[rwanttaja]

The 2 stroke reputation is from and earlier time when experimentation was without data.That Data gathered from all the bad experience and good , has its roots in today's engines and range of performance. I respect the past and would use the tried and rated.

Your comment made me curious, Norm: HAS two-stroke reliability increased with time?

One way to look at the issue is to examine the accidents involving homebuilt aircraft with two-stroke engines, and determine what percentage of the accidents were due to engine issue.

I split my database into two groups: 1998 through 2006 (nine years), and 2007 through 2016 (ten years). The slight difference in number of years doesn't make a difference, since we're look at the percentages rather than the raw numbers.

During the earlier period, 31.6% of accidents involving EAB aircraft with two-stroke engines were due to engine issues.
During the later period, that dropped to 21.4%! So, indeed, the homebuilt world got better at producing reliable two-stroke engine installations.

Here's the figures for several engine classes.

	1998-2006	2007-2016
Traditional Engines	14.2%	14.6%
Auto Engines	32.3%	32.2%
Non-Cert Four Strokes	20.2%	15.5%
Two-Strokes	31.6%	21.4%

"Non Cert Four Strokes" are engines like the Rotax 912 and the Jabiru. The Rotax 912 itself, in fact, dropped from 15% in the first period to 10% in the more-recent period...better than traditional engines, in fact.

Ron Wanttaja

[thisadviceisworthles]

The Rotax 912 itself, in fact, dropped from 15% in the first period to 10% in the more-recent period...better than traditional engines, in fact.

Ron,

How granular is that data, can you give a breakdown by engine? (I'm particularly curious about the Rotax 582, Rotax 503 and the HKS 700e)

[rwanttaja]

Ron,

How granular is that data, can you give a breakdown by engine? (I'm particularly curious about the Rotax 582, Rotax 503 and the HKS 700e)

It really depends on the thoroughness and accuracy of the NTSB reports. Often the engine just states "Rotax" with no model number; I don't count these on either the two-stroke or the non-certified four-stroke categories. My full database (1998-2016) shows 456 accidents involving aircraft with two-stroke engines (out of about 3800). The last ten years show only 168. These *are* just EAB-registered aircraft; I don't track Part 103 accidents.

For the full 19-year period, 106 EAB accidents had Rotax 503 variants, and 214 had Rotax 582. 21% of the 503 accidents were due to power issue, vs. 33% of the Rotax 582 cases. There are only four cases involving EAB aircraft with HKS engines. The power system wasn't cited in any of these, but that's just too low of a sample set. According to the FAA database as of a year ago, there were 198 aircraft registered with HKS engines. There were 13,508 listed as having Rotax engines. 1861 were listed as having 503s, 3226 as 582s, but the FAA registry lists just a bunch of generic "Rotax" or "Bombardier" engines with no model number.

Ron Wanttaja

[HAPPYDAN]

All good info. What I meant to say was, 2-stroke motorcycle engines were (are) virtually bomb-proof. Very reliable, and easy to service and maintain. The drawback: super polluters!

[Norman Langlois]

I did not base my comment on statistics . On the observed only. and plain logic . The ultra light era gave many individuals opportunities to create . The fly. Your own data shows a decline in incident. Sudden stoppage always has a root . Most will lead to a user error. water ,over rev, improper oil, poor maintenance. Its not the 2 stroke its that 2 strokes need a strict user guideline. That beginning era was indeed experimental with many failures. The answer is obvious ly Yes there are more reliable than before. But still no more reliable than in comparison to 4 stroke. Nether power plant is any better with poor human interaction. If one engine design has been improved to the point it is bullet poof only then would you lift your condemnation of 2 strokes. And that will take another 10 years of statistics and only if all aircraft going forward with 2 strokes are of that design. I do not expect to change your mind if you have a condemnation of 2 stroke use . If you feed your 4 stroke water and let the sump go dry it will stop also.