Do not forget to fly

Finally good weather here, and I have been doing some flying. It is very easy to forget about flying when building, but keeping current is important when the big day arrives. My gliding club has got a new tow plane. We had a Piper Pawnee that was a pure joy to fly, but now we have a Aerospool WT9 Dynamic. The WT9 is still being used for check rides to get enough current tow pilots on the type, so we had to rent a 180 HP Super Cub for a few weeks. I spent a couple of days tugging gliders this weekend. I have also been taking some gliding lessons,.

Engine

Watched/listened to the webcast from Sonex about the Aerovee engine.Very interesting to see how it became the engine it is today, and why it is a kit, not a finished engine. However, the lack of anything that can be called engineering in that engine, is all too obvious. All in all; a bit disappointing, still I am left with the impression that the engine is well tested in the field, the complete package is well thought through functionality vise, and that the engine will do what it is supposed to do. A good engine for the Onex? Yes.

Avgas UL91 is coming. Basically it is unleaded avgas 100LL and with octane numbers of 91 MON, 96 RON (whatever that actually means). Statoil is starting to sell this fuel in Norway. Avgas 91 UL is for all practical purposes aviation quality Mogas, and that can only be a good thing. The ability of the engine to run on UL91 is yet another additional important factor.

Name	Type	HP(max)	RPM(max)	cc	kg	Price €	TBO [H]	UL91	Mogas
Rotax	912 UL	80	2200	1300	72	€ 12 142	2 000	Y	95
Rotax	912 ULS	100	2200	1400	75	€ 13 499	2 000	Y	95
Rotax	912iS	100	2200	1400	75	€ 18 329	2 000	Y	95
Sauer	1800 UL	68	3200	1835	64	€ 7 845	1 600	Y	95
Sauer	2200 UL	85	3000	2234	66	€ 9 567	1 600	Y	98
Sauer	2400 UL	100	3500	2332	75	€ 10 574	1 600	Y	95
Sauer	S 2100 ULT	110	3000	2161	76	€ 13 586	1 600	Y	98
Limbach	L2400 EFI	100	3000	2424	76	€ 23 900	1 600	TBD	98
D-Motor	LF26	92	3000	2690	57	€ 12 600	1 500	Y	95
ULPower	260i	97	3300	2592	72	€ 14 700	1 500	Y	95
ULPower	260iS	107	3300	2592	72	€ 15 800	1 500	Y	98
D-Motor	LF39	130	3000	3993	79	€ 17 800	1 500	Y	95
ULPower	350i	118	3300	3503	78	€ 18 800	1 500	Y	95
Limbach	L2400 EB	84	3200	2424	82	€ 19 500	1 400	TBD	98
Revmaster	2300	85	3200	2331	77	€ 5 729	1 200	TBD	98*
Verner	Scarlet 7H	110	3500	4127	82	€ 11 990	600	Y	95
Hummel	2400	85	3600	2400	76	€ 4 850	0	TBD	98*
AeroVee	2.1	80	3400	2180	73	€ 5 083	0	TBD	98*
Great Plains	2300	80	3600	2276	75	€ 5 199	0	TBD	98*
AeroVee	2.2T	100	3400	2180	80	€ 7 266	0	TBD	TBD
Viking	Honda	110	2300	1500	81	€ 9 439	0	TBD	98
Jabiru	2200	85	3300	2200	64	€ 11 263	0	Y	95
Jabiru	3300	120	3300	3300	84	€ 14 460	0	Y	95

* with reduced compression ratio, and thus reduced HP and efficiency.

A tiny bit too early for a conclusion. But the Rotax, D-motor, Viking, Limbach, Verner is realistically no longer options for me. It will be too much work to redesign everything firewall FWD. Limbach is too costly etc. From the other manufacturers I have received very positive correspondence about how to proceed and what kind of help I can expect. Sauer will be a drop-in replacement, with only minor modifications. ULPower have a guy selling motor mounts, etc. The list is therefore shortened to:

Name	Type	HP(max)	RPM(max)	cc	kg	Price €	TBO [H]	UL91	Mogas
Sauer	2200 UL	85	3000	2234	66	€ 9 567	1 600	Y	98
Sauer	2400 UL	100	3500	2332	75	€ 10 574	1 600	Y	95
ULPower	260i	97	3300	2592	72	€ 14 700	1 500	Y	95
ULPower	260iS	107	3300	2592	72	€ 15 800	1 500	Y	98
ULPower	350i	118	3300	3503	78	€ 18 800	1 500	Y	95
Revmaster	2300	85	3200	2331	77	€ 5 729	1 200	TBD	98*
AeroVee	2.1	80	3400	2180	73	€ 5 083	0	TBD	98*
Great Plains	2300	80	3600	2276	75	€ 5 199	0	TBD	98*
AeroVee	2.2T	100	3400	2180	80	€ 7 266	0	TBD	TBD
Jabiru	3300	120	3300	3300	84	€ 14 460	0	Y	95

To achieve 80/85 HP on the american VW conversions, I will have to use 100LL. A fuel that may not be available for much longer. All the other engines runs equally well on UL91 and Mogas.

Left wing and rear mid spar

Drilled and riveted in the left side angle bracket that were wrong, and riveted on the rear spar.

Then I remembered I have one more spar, the rear mid spar. Drilling, deburring and started stacking. The outer spars are going to slide into the mid spar. It will be interesting to see how that works out when Sonex had no measurements to give out when the brackets had to change.

Left wing

Fixed the remaining two ribs and the aileron paddle

Left wing

Riveted together the inner most rib doublers and bracket. Riveted on the outer ribs.

Left wing and the ONX-W10-03 fix

Continued on the left wing. Countersinking holes and riveting aileron brackets. Finally received the angle stock from ACS, and made new angles for the aft main spar according to this from Sonex aircraft. The description from Sonex of what is wrong and how the parts are to go together to make it right is nonexistent, and the drawings give no dimensions whatsoever. Sonex isn't even willing to send me new correct parts. Really disappointing.

The error is the pilot holes in the angle is too far down so the aft spar will be mounted too high. The result in the skin will not fit. With the new angle made, it is easy to get the rear spar to fit using some aluminium strips. The problem is getting the dimension along the aft spar correct. I used the bolt holes for the original angles, since there are no dimensions in the drawings.

Main spar

The last 1 inch rivet in place. The spot is when I tried to clean the primed spar with some new silicone remover, not a good idea.

Main spar

Even with the C-frame on the concrete floor, the manufactured head did not set properly on the 1 inch rivets. The fastest way, by far, was to use a large and heavy and long bucking bar and the rivet gun on all rivets. With the long bar it was much easier to get the shop head straight compared with the small tungsten bar. The difficult part with this was to push hard enough on the rivet gun. Have to remember this the next time I make a main spar :-)

Riveting the main spar

Clecoed together the spar with the steel parts just to make sure the bolts would go in right. Then I removed the steel.

Started riveting with the C-frame on the concrete floor, but my back said "no". So continued on the table. For the smaller rivets all went fine.

The the -16 rivets also seemingly went fine until I I looked on the manufactured head. They were not set properly, large gaps between the head and the angle. Just not enough metal in the C-frame for these long rivets.

Had to drill them out. Then continue by hand with the rivet gun and the Tungsten bucking bar. A bit difficult to get the same consistency on the shop head by hand compared to the C-frame on these large and long rivets, but OK enough, and the manufactured head is totally flush.

Main spar primed

Deburred and primed the main spar, also the steel parts. I leave it to cure overnight.

Main spar

Finally finished with all the holes in the main mid spar including all the steel parts. Priming and riveting next. It's a lot of work with a surprisingly large amount of parts that together constitute the main mid spar in an intricate but well thought out manner. The folding mechanism also makes a lot of parts. A drill press would probably speed up the work a lot, and the pre-made spar option is probably a good choice also.  

New controller

In Norway we need to have controllers appointed by Luftfartstilsynet. Their job is to sign the build log and to give advice and help. The build log is a document that is to follow the aircraft through it's lifetime, it's the documentation that all parts are OK. It's a way of quality assurance of the build process and the finished parts. I think this build log is a very good thing, particularly when selling/buying used experimental aircraft. I would never dream of buying a used experimental from the US, where there is no requirement to document the build process.

My old controller moved to another part of the country. I couldn't close up the structure, horizontal and vertical tail surfaces, before the controller had inspected and signed off. I have used some time to find a new one, but when I finally got a new one, he happened to live only a couple of hundred meters from my home. So finally I can close up stuff and be finished with pieces.   

Engines

Which engine to get is a hard nut to crack. I have updated my list and also included TBO. The reason is that the geography in Norway is very different from the European or American mainland. Good emergency landing spaces are far apart, 99% of the country is either woods, mountains or water, and none of those are good places to land in an emergency. I have to be somewhat lucky to survive, very lucky not to be injured and extremely lucky not to wreck the aircraft. Having flown only in Norway, mostly with certified Lycoming/Continentals or the ever-running Rotax, I haven't given it that much thought until I the engine stopped in a Piper Pawnee last year. I was extremely lucky to be able to glide back to the airfield and make a good power off landing with no damage whatsoever, but will I ever be that lucky again? From a practical point of view surviveability is handled in one of three ways for a single engine aircraft.

1. A very reliable engine.
2. Low impact velocity and or low kinetic energy (low stall speed and low weight).
3. Emergency ballistic system or parachute.

It is obvious from the above list that the single most important factor to protect pilot and airplane is a reliable engine combined with good airmanship (always look for emergency landing spots etc). 2 will most certainly help regarding both surviveability and damage to the aircraft if the engine stops. The Onex do not have a particularly low stall speed, but the weight is low. Number 3 I am not sure is such a good idea at all in relation to the risk of engine stopping. I see 3 as a solution to other cases such as the risk of colliding in gliders or perhaps mechanical failure of the aircraft structure when doing aerobatics.

The only meaningful obtainable number regarding the reliability of an aircraft engine is the TBO. TBO is not the same as MTTF, but it is correlated. A set TBO means the MTTF is well within acceptable limits, if the engine is maintained properly and is operated within the TBO. My general experience also suggests that Lycoming, Continental and Rotax are extremely reliable engines, and these three all have a TBO of 2000+ hours.

With this in mind, the choice of engine becomes more interesting. TBO will be a number to take into consideration. Originally my position was to find an alternative to the Aerovee, one that was not too costly and one that I didn't have to put together myself. Today my position is in fact to find good and relevant reasons (excuses?) for not installing a Rotax 912. This means my engine alternatives have changed and have narrowed down to Rotax, Sauer and ULPower with Jabiru 2200/3300 as possible options.

Name	Type	HP(max)	RPM(max)	cc	kg	Price €	TBO [H]
Rotax	912 UL	80	2200	1300	72	€ 12 142	2 000
Rotax	912 ULS	100	2200	1400	75	€ 13 499	2 000
Rotax	912iS	100	2200	1400	75	€ 18 329	2 000
Sauer	1800 UL	68	3200	1835	64	€ 7 845	1 600
Sauer	2200 UL	85	3000	2234	66	€ 9 567	1 600
Sauer	2400 UL	100	3500	2332	75	€ 10 574	1 600
Sauer	S 2100 ULT	110	3000	2161	76	€ 13 586	1 600
Limbach	L2400 EFI	100	3000	2424	76	€ 23 900	1 600
D-Motor	LF26	92	3000	2690	57	€ 12 600	1 500
ULPower	260i	97	3300	2592	72	€ 14 700	1 500
ULPower	260iS	107	3300	2592	72	€ 15 800	1 500
D-Motor	LF39	130	3000	3993	79	€ 17 800	1 500
ULPower	350i	118	3300	3503	78	€ 18 800	1 500
Limbach	L2400 EB	84	3200	2424	82	€ 19 500	1 400
Verner	Scarlet 7H	110	3500	4127	82	€ 11 990	600
Hummel	2400	85	3600	2400	76	€ 4 850	0
AeroVee	2.1	80	3400	2180	73	€ 5 083	0
Great Plains	2300	80	3600	2276	75	€ 5 199	0
Revmaster	2300	85	3200	2331	77	€ 5 729	0
AeroVee	2.2T	100	3400	2180	80	€ 7 266	0
Viking	Honda	110	2300	1500	81	€ 9 439	0
Jabiru	2200	85	3300	2200	64	€ 11 263	0
Jabiru	3300	120	3300	3300	84	€ 14 460	0

Engines with no TBO (zero TBO) runs in a state of "on condition". This is the same state as a Lycoming/Rotax that has exceeded its TBO runs in. What does this really mean? Well, this is basic maintenance and reliability theories in action in real life. An engine that runs within its TBO has an MTTF or MTBF that is constant and known. That is, as long as the engine is operated and maintained according to the factory documents,  the failure modes are known and happens so seldom that the risk is acceptable. The risk of sudden catastrophic failure of the engine parts (considering everything else is OK) is non existent from a practical point of view. When exceeding the TBO, the wear and tear on the engine starts to affect the reliability and any number of random things may happen at any time.

A TBO assures the engine will be reliable within its TBO, with a predetermined and very specific set of maintenance. With no TBO the engine can also be just as reliable, theoretically, but you have no idea what kind of maintenance is needed, or how often you have to do it. With no TBO, it runs "on condition". For a Lycoming this is OK for a limited time because the large number of engines in operation has limited the things to look for to a few points during condition inspection. For an engine that is put together by random aftermarket auto parts with no track of the origin, you have no idea, literally. You have no idea what to look for, thus no idea how to maintain it to assure it will run without failure the next hour.

So, an engine with a TBO is a world of difference better than an engine with no TBO, anyone saying differently don't know what they are talking about. It is better because you know how to maintain it, you know what to maintain and you know when to maintain it to be sure it will run without problems the next hours.

For practical purposes this means that a VW engine wizard will have no problems operating and running a VW aero engine conversion, and it will be every bit as reliable as a Lycoming. He knows what to look for, he knows what parts are OK, which aftermarket manufacturers are OK, how long each part last and so on. He will always be one step ahead of any failure waiting to happen. Myself, I am no VW engine wizard, I am no [any engine] engine wizard. So the only way for me to achieve a reliable engine is an engine with a TBO and a specific maintenance schedule within that TBO.

More bolts in the spar

The right side. The black plastic liner is to be placed on the fwd side (obviously when thinking about it).

Except for 30 and 40 drill bits, the Drill Doctor works excellent.