IBob

Here is part 2:

The raffle was for a fly in a WW1 aircraft.

Supposedly the pilots also ingested the oil, and suffered the laxative results. A few years back I won a raffle for a fly in an SE5a: to enter, I bought a ticket, but also had to down a large tot of castor oil. I was also offered a tot of some fruit liquer (blackcurrant?), which some WW1 pilots claimed as an antidote. They told me it would take 2 to 3 hrs to start emptying my system. They were about right............

It's a dead giveaway: 'Sniffs the air......" Yep, them Fokkers have been around again..."............

Rotary engines take air and fuel into the crankcase through the hollow (stationary) crankshaft. From there it makes it's way to the individual cylinder inlet ports, usually via external duct pipes. To maintain crankcase etc lubrication, oil is injected with the air fuel mixture, as it is in 2-stroke motors, though the rotary is a 4-stroke motor. Here is an interesting summary: https://www.historynet.com/the-truth-about-rotaries.htm It includes the quote: “Rotary engines became quickly outdated for a couple of reasons, but mostly because of the large quantity of Castrol required to keep a squadron of rotary-powered airplanes in the air. Most rotary engines consume about five or six quarts of oil per hour.”

In many early engines, the valve gear is exposed, so there is no way to capture and recirculate the oil that lubricates the rockers and stems: it is what is known as a total loss oil system. In something like the rotary Oberursal engine, there would be the added difficulty of how to get oil back from the heads, given that the whole engine is rotating. As Facthunter said, this oil blows back over aircraft and pilot. And you get whiffs of it all over the airfield when these things are flying.

As noted earlier, they're building new ones here at Hood. And far more complicated engines too. The reason being that the very small pool of surviving originals has pretty much dried up. So to build the aircraft of the time, they are having to build the engines of the time too. Not much demand, admittedly: mostly museums and private collections.

They knew how to build light.....probably a question of having to, but impressive nevertheless.

OME the vortex generators on the Savannah are stuck on with superglue. When it came to doing the job, I was able to buy a little bottle of the glue with integral brush attached to the lid, just like nail varnish. I found that a very easy way to apply small amounts of glue, and spread it evenly. Can't recall the brand, but I'm pretty sure I got it at Supercheap Auto.

OME Paramushir is an Island off the Kamchatka Peninsula, occupied in WW2 by the Japanese, with multiple airstrips and bases. A Russian translator showed us round the little museum there. On the wall was a picture of a Russian general of Mongolian extraction, who he said should have been shot. The story he told went as follows In addition to extensive military operations, the Japanese had a Russian POW camp on Paramushir. With the end of the war in sight, they loaded the POWs on boats, took them out to sea and dropped them over the side. On Aug14 1945, the Japanese unconditionally surrendered. However, the Russian general, wishing for a decisive win on his CV, requested and was granted leave to 'take' Paramushir by force. Russian troops arrived by ship Aug18, however, they put in to the wrong bay, and 2 of every three drowned while trying to reach the shore. The history books say that sporadic fighting then continued until Aug23, however the translator told us the Japanese met the Russians with white flags and were machine gunned. It is a fishing island, and the locals said they were fishing up bones for years. The main fishing town was wiped out in 1952 by the Severo Kurilsk tsunami. The locals told us the KGB visited the survivors and cautioned them against talking about it. The local theory is that the tsunami was the result of a bomb test. In 1983 commercial flight KAL007 'strayed' into Soviet air space and was shot down. One theory in the West was that the incursion was deliberate, intended to provoke the USSR into lighting up all their defence gear, much of it on Paramushir, so the US could get a look at it. We asked the translator about that and were told the official line: supposedly Russia had shot down 15 enemy aircraft that day, unfortunately one turned out to be civilian. I don't think he believed it: there were a lot of Russians jokes about their own propaganda. In 1986 when I was there, the island was still littered with old munitions, the local children periodically blowing bits off themselves while playing with them. It's a place of severe winter weather, and there are fewer people there now.

I worked alongside NATO troops in Germany, late '60s early '70s. I heard a few stories about things that happened during WW2 there, the reasons and the justifications. Now, when I read back about those same events and incidents, I find the stories are sometimes quite different, and usually nothing like as clear cut as what I was told back then. It can be very hard to arrive at what actually happened and why. The victors get to write the history in the first instance, and the propaganda can last a very long time. I have learnt to be wary of the official line.

Terrific mass Mitchell takeoff footage from the original Catch 22:

Interesting writeup on the reverse engineering and subsequent build of new Oberursal UR.II engines to go in the 'new ' Fokker DVIIIs (of which there are now at least 2): https://thevintageaviator.co.nz/projects/oberursel-engine/oberursel-ur-ii-rotary-engine-build-history

Yesterday I watched one of these take off...and climb like crazy. According to Wikipedia, the climb rate is 1640ft a minute, or 10min 45sec to13,000ft. MAUW 605Kg, engine Oberursel UR.II 9-cyl. air-cooled rotary 110 hp Pretty good for a 100year old microlight!!!

KGWilson, I believe (at least) one of those was an all new airframe build, since the airframe of the original donor aircraft was too far gone. Which meant they had to make moulds for the fuselage. If they now own the moulds, they must be uniquely placed for further rebuilds.

Thanks for that, Downunder. #40 and #30 only required for the Savannah (I think). If I were starting again, I would definitely get them: as stated earlier, it was the only tool I did not have that I wished I had.

Really nice looking tools, Yenn. However, here again we run into the countersink angle problem: the tools offered by Aircraft Spruce cut a 100deg countersink, but the standard countersunk blind rivet has a 120deg head. And this is what I kept running up against when trying to source individual countersink bits...

You are absolutely right, Facthunter, and unless both job and drill are rigidly held, the result will not be a precise neat countersink. So, it's certainly not best practise. However, the tailfin Luca is working on does this in two places: First to hold two nut plates on the back of the main post. Second at the bottom of the skin on one side, where the rivets will be alternated with rivnuts, which then hold in place an inspection panel. These are typical of the (limited) use of countersunk rivets on the Savannah: nowhere are they used solely to hold a skin on. Typically they are used where something else will be mounted over the rivets, which therefore need to be flush. I am not aware of any failures due to this on Savannahs, or 701s.

PS while there are lots of countersink drill bits advertised, almost all of them (like this one) have the wrong countersink angle for the rivets we are using.

1. I'm sure Derekliston's reply above is the correct way to be doing it. However, as he points out, it is necessary to dimple both the skin and the part it is being riveted to, or the skin will not sit down flush 2. However, at the very start of the Savannah manual (General Information, page 2/12) where it outlines various techniques, it says for countersinking 'Just remove the material that is necessary to make the head of the rivet flush with a drill bit'. While this may not be ideal, I expect it is what most builders do. And in the places where rivets are countersunk on the Savannah, it does seem to work okay. 3. If doing it this way: Use a much larger drill (8mm or larger) Ensure that the drill tip is the correct angle (not all drills have the same tip angle, see attached pic) Turn the drill by hand and NOT with an electric drill. It's okay to have the drill bit in a drill, but turn it by hand, not with the power. The reason for this is that if you use the drill to turn it, it is very difficult to control the depth of the cut, and very easy for the drill to grab and pull entirely through, leaving you with a big hole. 4. While this does the job, if I was building again, I would buy a countersink drill bit: this has a tip that fits through the hole and keeps the bit centered. It was the one tool I did not have that I wish I had had.

Another very special aircraft........sigh...........)

Some really good input, and much to think about here for me. Thanks to all. In many ways the Savannah is an easy case, being high winged. And the 6litre receiver behind the seat, with low level switch in the top, is an excellent part of the setup: provided the switch and indicators are working, the pilot is alerted when down to 5litres of fuel in the receiver. (And the one proviso here is that the test button on the panel tests only the indicators, it cannot test the switch. So if intending to use the indicator to fly a tank dry, I first test the low level setup on the ground by valving off all fuel to the receiver, and looking for the indicators to come on during initial runup and taxiiing.)

The vast majority of Savannahs are tricycle undercarriage, and work very well that way. My thought is that while the tailwheel probably has some advantages for specific operators/applications, if it was generally a better configuration there would be more demand. I'm ambivalent about the Y stick: there are many configurations of aircraft controls, and provided they are not uncomfortable, you just get used to them. The Y stick has to be easier to get in and out of, unless you have removable sticks.

Nobody, thanks again. I believe I have seen the underwing vent on a 185: from memory approx 3/8 pipe bent forward like a stubby pitot. Interesting to note it has a check valve: I imagine this would be a simple swing valve. Yes, given the large effects of very small pressure changes, the cross-venting makes every sense.

Nobody, thank you, I wasn't aware of that, and it's given me something to think on. Putting on my fix a problem and make a problem hat (something I seem to have a talent for): with the 172 arrangement you describe you'd need to be very sure that single vent could not be blocked, or you would lose all fuel feed....