Tom Baker Posted January 27, 2017 Report Share Posted January 27, 2017 Totally agree. While spins have nothing to do with going point A to B these airplane do get used for other things. Back in 2008 when the CTLS was introduced there was a big push to develop Flight Design training centers. If you want a flight school to buy an airplane for flight training, it needs to be able to do as many of the training task as possible. IMO the airplane needs to be inexpensive to operate, reliable, durable, and able to perform as may of the maneuvers required for flight training as possible. Link to comment Share on other sites More sharing options...
Tom Baker Posted January 27, 2017 Report Share Posted January 27, 2017 The 'normal' class CT POH and the placarding in the aircraft say no intentional (or inadvertent) spins. Pulling out of at the bottom of spin presents the danger of excessive loads that can either damage the plane or worse. You just don't get it and probably never will. While both of your statements are true individually the 2 don't go exclusively together. The reason for the placard has nothing to do with excessive load during recovery from a spin. The reason for the placard comes from ASTM certification standards and not wanting the risk of liability exposure from allowing spins. Another thought on spins not being approved could have to do with the limits of the Rotax oil system. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 27, 2017 Report Share Posted January 27, 2017 Pulling out of at the bottom of spin presents the danger of excessive loads that can either damage the plane or worse. That is the case for every airplane ever flown. Obviously if you ham-fist any airplane you can "damage the plane or worse". Link to comment Share on other sites More sharing options...
gbigs Posted January 27, 2017 Report Share Posted January 27, 2017 That is the case for every airplane ever flown. Obviously if you ham-fist any airplane you can "damage the plane or worse". Let's rephrase. The load factors are 'normal' class for the CT: Up to Va +4g/–2g Up to Vne +4g/–2g This is also why the maxium bank in a turn for the CT is 60 degrees. Acrobatic aircraft have double these load factors. This allows such aircraft to safely make abrupt steep bank angles, hard pull-outs at the bottom of a dive, and spin and recover the plane without damage. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 27, 2017 Report Share Posted January 27, 2017 Let's rephrase. The load factors are 'normal' class for the CT: Up to Va +4g/–2g Up to Vne +4g/–2g This is also why the maxium bank in a turn for the CT is 60 degrees. Acrobatic aircraft have double these load factors. This allows such aircraft to safely make abrupt steep bank angles, hard pull-outs at the bottom of a dive, and spin and recover the plane without damage. There are *many* normal category (3.8g to 4g) airplanes out there that are spin rated. There is nothing frail about a 4g limit; go up some time and do 2 or 2.5g in your Cirrus, it's a LOT. I did 3.8g one time at the bottom of a wingover in a Sonex (rated +6/-3) and thought my head was going to fall through my ass. You don't need a "hard pull out" to recover a spin, unless the ground is rushing up at you. A 1.5g pull is significant and plenty. After all, if you PARE'ed correctly the engine is at idle, it's not like you are screaming down at Vne. You are just nose low as in an abrupt stall recovery. Link to comment Share on other sites More sharing options...
Buckaroo Posted January 27, 2017 Author Report Share Posted January 27, 2017 I read the CT had a "break point" of 9 plus g's. It was a measurement of g's I think. What I invisioned that to be was placing the aircraft on some wing supported device that's the force it would take to snap it pressing down on the aircraft. Can anyone chime in? Link to comment Share on other sites More sharing options...
Tom Baker Posted January 27, 2017 Report Share Posted January 27, 2017 Let's rephrase. The load factors are 'normal' class for the CT: Up to Va +4g/–2g Up to Vne +4g/–2g This is also why the maxium bank in a turn for the CT is 60 degrees. Acrobatic aircraft have double these load factors. This allows such aircraft to safely make abrupt steep bank angles, hard pull-outs at the bottom of a dive, and spin and recover the plane without damage. There is no "Normal class" for airplanes. You are confusing it with standard category. The load factor for standard category is 3.8 positive and 1.52 negative. For aerobatic category it is 6 positive and 3 negative. Utility is in between at 4.4 positive and 1.76 negative. However the CT is not certified in these categories. It is certified under ASTM standards. The best I can tell ASTM is 4 positive and .5 negative. Having done plenty of spins in my flying career I can tell you that in a normal recovery you don't get anywhere close to those load factors. For compliance with ASTM standards airplanes have to be spin tested, and found to be fully recoverable with no bad habits. The only difference between the airplanes placarded "no intentional spins" and those that are not, is how far the spins are allowed to develop before recovery is initiated and how quick they have to recover. Link to comment Share on other sites More sharing options...
Tom Baker Posted January 27, 2017 Report Share Posted January 27, 2017 I read the CT had a "break point" of 9 plus g's. It was a measurement of g's I think. What I invisioned that to be was placing the aircraft on some wing supported device that's the force it would take to snap it pressing down on the aircraft. Can anyone chime in? If I remember correctly they tested the ultimate load to something close to that number. The AOI states +4 and -2. Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 28, 2017 Report Share Posted January 28, 2017 If I remember correctly they tested the ultimate load to something close to that number. The AOI states +4 and -2. Is that true for the whole airframe? I'd believe the wing could do 9g ultimate, but the tail is awfully flimsy... Link to comment Share on other sites More sharing options...
Tom Baker Posted January 28, 2017 Report Share Posted January 28, 2017 Is that true for the whole airframe? I'd believe the wing could do 9g ultimate, but the tail is awfully flimsy... It may have been just the wing, but the whole airplane should have an ultimate of 6 positive. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 28, 2017 Report Share Posted January 28, 2017 It was 7 and the stab is the weakest point. That's what killed a pilot in Europe at an airshow. You screw up and pull more than you want and the stab will collapse. Link to comment Share on other sites More sharing options...
Tom Baker Posted January 28, 2017 Report Share Posted January 28, 2017 It was 7 and the stab is the weakest point. That's what killed a pilot in Europe at an airshow. You screw up and pull more than you want and the stab will collapse. Roger, G loads was not the cause of that accident. It was flutter from exceeding VNE. The accident is discussed in this article. https://www.recreationalflying.com/tutorials/safety/excess_speed2.html Link to comment Share on other sites More sharing options...
Roger Lee Posted January 28, 2017 Report Share Posted January 28, 2017 Hi Tom, You're right. Link to comment Share on other sites More sharing options...
Buckaroo Posted January 28, 2017 Author Report Share Posted January 28, 2017 Roger, G loads was not the cause of that accident. It was flutter from exceeding VNE. The accident is discussed in this article. https://www.recreationalflying.com/tutorials/safety/excess_speed2.html That's a great read! I never thought of how speed can twist a wing setting it up aerodynamically to do the reverse of what is expected! I'll be our clean light aircraft can get real fast speedily!???? This would be great to instill in student pilots! Link to comment Share on other sites More sharing options...
WmInce Posted January 28, 2017 Report Share Posted January 28, 2017 On oil temp in flight Rotax would like the temp to reach at least 190° at some point in the flight. If you can achieve that ,then temps in the 130's will not be an issue. Just watch that the temp doesn't get below the 122° mark. If it does the oil filter bypass can kick in and put contaminants back into the oil system. That black area that you talked about on the oil temp gauge will change to green as soon as your oil temp reaches the 190° mark, if it is not reached it will stay black. Tom, Does that mean . . . during engine warm up, just after start, until the oil temp reaches at least 122° mark, the oil filter operates in the bypass mode? Link to comment Share on other sites More sharing options...
Tom Baker Posted January 28, 2017 Report Share Posted January 28, 2017 Tom, Does that mean . . . during engine warm up, just after start, until the oil temp reaches at least 122° mark, the oil filter operates in the bypass mode? That is a good question. I was just repeating what I was taught in Rotax class. There is also a RPM limitation when operating below the 122°F number. It could be that the lower RPM's will help prevent the filter from bypassing. Link to comment Share on other sites More sharing options...
gbigs Posted January 28, 2017 Report Share Posted January 28, 2017 I read the CT had a "break point" of 9 plus g's. It was a measurement of g's I think. What I invisioned that to be was placing the aircraft on some wing supported device that's the force it would take to snap it pressing down on the aircraft. Can anyone chime in? It was a test of the wing spar. That has nothing to do with half the plane breaking up if you over-stress outside it's design envelope. Namely, you could lose the wing portions beyond the spar, vertical stabilizer, elevator, empenage, ailerons, flaps or even the prop if you tempt fate. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 28, 2017 Report Share Posted January 28, 2017 The oil filter does not work in bypass after start up. It does open briefly at start because of the pressure differential upstream and downstream. It closes fairly quickly. Bypass only works when there is a differential pressure. That means high upstream pressure at the front of the filter and a low downstream after the filter. After start the pressure equalises. I'll be showing the guys in my class this next weekend how the filter works internally. I have many parts that have been cut for demos. The reason Rotax uses the 120ish mark is it gives time for all the metals to heat and expand throughout the engine. Link to comment Share on other sites More sharing options...
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