bushpilot Posted December 22, 2008 Share Posted December 22, 2008 Guys, Wondering if there are any views out there on this one: Using my one-way, uphill E-W strip, I sometimes land with up to 10kts of tailwind, up the hill (Westerlies), and take-off with up to 10kts of tail down the hill, in Easterlies. Of course my GS is then 10kts higher than normal - on touch down or lift off.. So I'm wondering if this has any real impact on my Jab 160C undercarriage? (It looks pretty solid compared to earlier Jabs - especially the nosewheel assembly.) Also, is there any difference between gusts and lulls? i.e. when Im landing with tail, I tend to be on final with a bit more speed than normal, in case I get a tail gust. But is this any more of a risk than a lull when landing into wind? (Can a gust vary AS more quickly than a lull?) Cheers Chris Pic. The top 70% of my strip Link to comment Share on other sites More sharing options...
turboplanner Posted December 22, 2008 Share Posted December 22, 2008 Think there may be something on this situation in Stick and Rudder Link to comment Share on other sites More sharing options...
Ultralights Posted December 22, 2008 Share Posted December 22, 2008 in nil wind, landing at 60Kts IAS= 60kts ground speed 10 kt tail wind= 70kts ground speed 10kt headwind= 50 kts ground speed. so slowing from 70 kts touchdown ground speed takes a considerable distance more than 60 kts, and 75% more than landing with 50 kts groundspeed. then you have to factor in slope and it effects on braking distance. 70 kts is 130kph, 50 kts is about 90kph. this help give a reference to how much more distance is required to stop, try it in a car. Link to comment Share on other sites More sharing options...
bushpilot Posted December 22, 2008 Author Share Posted December 22, 2008 in nil wind, landing at 60Kts IAS= 60kts ground speed10 kt tail wind= 70kts ground speed 10kt headwind= 50 kts ground speed. so slowing from 70 kts touchdown ground speed takes a considerable distance more than 60 kts, and 75% more than landing with 50 kts groundspeed. then you have to factor in slope and it effects on braking distance. 70 kts is 130kph, 50 kts is about 90kph. this help give a reference to how much more distance is required to stop, try it in a car. In my situation distance is not an issue; the up-slope washes off speed quickly; also assists a bit with T/O (down-hill). My interest is in the robustness of the undercarriage; I assume (hope) it is way over-engineered. My other Q is the gusts & lulls thing; maybe there is someone out there that knows a lot more than me about meteorology.. and topographic affects.. Link to comment Share on other sites More sharing options...
Tomo Posted December 22, 2008 Share Posted December 22, 2008 I've seen them test the undercarriage of the Jab's, and they give them a big canning to which they withstand...so assuming that it can handle that you'd think it should be alright with your situation... I think you can actually view a video of them testing the undercarriage of the Jabiru on there website somewhere... But I should let the experts do the talking....just thought i'd let you know what I've seen... Link to comment Share on other sites More sharing options...
Deskpilot Posted December 23, 2008 Share Posted December 23, 2008 It's a high speed, heavy landing that will wreck your under-carriage, not high speed alone. Give the wheels time to spin up without loading the u/c unduly and you could land a 100 knots. If they can't spin up fast enough before the max weight is applied, the twisting motion on the mounting bolts will result in failure. Drop tests only test structures in one axis where as an actual landing stresses in two. The fore/aft axis is what will rip the u/c off if applied too harshly. Does that make sense? Link to comment Share on other sites More sharing options...
Chird65 Posted December 23, 2008 Share Posted December 23, 2008 Hey desk pilot so the go would be to add vanes to the wheels that start the wheels turning:hittinghead:. or maybe a couple of small electric motors:juggle: Link to comment Share on other sites More sharing options...
Tomo Posted December 23, 2008 Share Posted December 23, 2008 Drop tests only test structures in one axis where as an actual landing stresses in two. The fore/aft axis is what will rip the u/c off if applied too harshly. Does that make sense? Yes I did sort of wonder if that was a problem...that's probably a bit of a hard test to do though, statically and in a shed anyway... Chird65: If i'm correct, that's what they do on Jumbo jets isn't it? but with compressed air instead... :big_grin: Link to comment Share on other sites More sharing options...
BigPete Posted December 23, 2008 Share Posted December 23, 2008 There are three rules to land without damage to the undercarriage: :thumb_up: 1. Keep the bloody nose wheel up, (on touchdown) 2. Keep the bloddy nosewheel up, and (after touchdown), 3. Keep the bloody nosewheel up. (as long as possible after touchdown) The main gear on a J160c is very strong and will take a fair pounding. :thumb_up: Treat the nosewheel like its made of tissue paper and you won't go far wrong. :big_grin: When taking off down hill, get as much weight as you can off the front wheel as soon as you can, as well. regards :big_grin::big_grin: Link to comment Share on other sites More sharing options...
poteroo Posted December 23, 2008 Share Posted December 23, 2008 Big Pete is absolutely right, right and right. The J-160 nose wheel is the weak link. Leave some power on so you can achieve a nose high attitude before the mains touch. happy days, Link to comment Share on other sites More sharing options...
Deskpilot Posted December 23, 2008 Share Posted December 23, 2008 I don't know of any planes where the wheels are spun up. During the war, they tried it in Spitfires for some reason and it only resulted in crashes. Don't know why. As far as I know, the only thing that worked when spun up was the dam busters bomb. Link to comment Share on other sites More sharing options...
ahlocks Posted December 23, 2008 Share Posted December 23, 2008 ...Leave some power on so you can achieve a nose high attitude before the mains touch.happy days, No disrespect toward the mighty Jabirooster, or the technique, but I'm ambivalent to leaving power on right through to touchdown. My reason being, that the most likely time that the nose wheel will be damaged will be during an off field landing and I'd imagine that it's fairly likely that the motor not running will be the very cause of that landing. So to me, if every landing is the equivalent of an engine out landing, i.e. glide approach and touchdown, the off fielder should be a no brainer 'cuz you've had lots of practise doing them... Horses for courses I suppose. Cheers! Link to comment Share on other sites More sharing options...
bushpilot Posted December 23, 2008 Author Share Posted December 23, 2008 Big Pete is absolutely right, right and right. The J-160 nose wheel is the weak link.Leave some power on so you can achieve a nose high attitude before the mains touch. happy days, Whilst others have questioned the logic of this suggestion, it could be the very thing that I need to do... Remember, I am landing on a grassy up-slope, which means that with power at idle only, it's difficult to grease it on; I typically 'thud' it on a bit... So a bit of power should allow me to better match the slope and flare as per normal.. Cheers. Link to comment Share on other sites More sharing options...
ahlocks Posted December 23, 2008 Share Posted December 23, 2008 Yeah, concur. I should have considered the context rather than thinking of generic landings. Cheers! Link to comment Share on other sites More sharing options...
facthunter Posted December 23, 2008 Share Posted December 23, 2008 Difference. BP. The difference in landing on a level field compared to landing on an upslope, is that you are landing from a CLIMB Therefore you have to have more energy from power applied/ retained or have a surplus of airspeed (kinetic energy) Nev.. Link to comment Share on other sites More sharing options...
Student Pilot Posted December 23, 2008 Share Posted December 23, 2008 BP. The difference in landing on a level field compared to landing on an upslope, is that you are landing from a CLIMB Therefore you have to have more energy from power applied/ retained or have a surplus of airspeed (kinetic energy) Nev.. I think you were trying to say it slows up quicker Nev? ;) Link to comment Share on other sites More sharing options...
poteroo Posted December 24, 2008 Share Posted December 24, 2008 It was certainly meant in the context of rough field &/or, uphill landings. Taken from the accumulated experience of 5 years flying C180/185 in PNG and an ANO 28 'all over' PNG exemption for commercial ops. And now I fly a J-160 ! happy days, Link to comment Share on other sites More sharing options...
motzartmerv Posted December 24, 2008 Share Posted December 24, 2008 so NOW your a real pilot?? Link to comment Share on other sites More sharing options...
farri Posted December 24, 2008 Share Posted December 24, 2008 When Is Fast Too Fast? When you can`t stop the blody thing. Frank. "Flying Is Easy,Crashing Is Hard". Link to comment Share on other sites More sharing options...
facthunter Posted December 24, 2008 Share Posted December 24, 2008 The original question. When is FAST too fast? When the speed that you have made your approach at is excessive, prolonging the flare and hold-off, in order to achieve a normal touchdown speed and attitude. You know that you are "HOT" when you float excessively. Nev.. Link to comment Share on other sites More sharing options...
motzartmerv Posted December 24, 2008 Share Posted December 24, 2008 Ofcourse that depends on the groundspeed or airspeed being excessive.. If the IAS is high then an extended float will occur.. But i think the thread starter is talking about a normal approach speed, with a tailwind. so GS will be high but IAS would be normal.. In my mind this could cause problems as the Picture will be telling the brain you are fast, when in reality the airspeed is low and decreasing as you try to wash off the percieved extra speed.. So extra care will need to be taken in the situation he has described..And i agree, power would help with the atitude problems in the flare.. cheers Link to comment Share on other sites More sharing options...
facthunter Posted December 25, 2008 Share Posted December 25, 2008 Response. Point taken andy, but my consideration here was with airspeed only. The illusion of high (air)speed, caused by the existance of a tailwind, may lead the pilot to fly too slowly and have the usual consequences, ie have insufficient extra lift to flare. Usually the 'windshear/ gradient near the ground will save the situation there. You never see "birds" landing downwind. (unless they are very young). The practice of landing downwind became commonplace with heavies and preferred runways (noise sensitive areas related) and anti-skid systems were universal. The demise of the DC-3's and some british T/W's allowed it too. Spoilers (Manual and pre-armed) need to be available to smooth out the environmental variables, and prevent landing over-runs. It's still very hard on brakes, and brake overheats are fairly common.. Nev.. Link to comment Share on other sites More sharing options...
motzartmerv Posted December 25, 2008 Share Posted December 25, 2008 Nev, did you fly the Dak's?.. I was lucky enough recently to help an old engineer run the dak's up at albatross.. was an absolute blast.. Love those old school engines coughing into life.. Ive just started my command instrument rating, while we were in the cockpit of the dak with the motors purring i tried to imagine what it would have been like in the old days doing syd- melb in all weather with just a forcast wind to navigate with.. They must have bread em tough back then;).. Ive gained a new respect for the guys that used to handfly in full IFR conditions in these old birds.. Great stuff.. sorry to get off topic.. Merry xmass all.. Link to comment Share on other sites More sharing options...
Yenn Posted December 25, 2008 Share Posted December 25, 2008 Landing with a tailwind not only gives the pilot a feeling of excess speed due to the speed over the ground, but more importantly you need to be aware that your approach will look lower or flatter due to the same reason. If you are landing downwind and keep the normal sight window, you will most often end up high and have to lose height without gaining speed. Try sideslipping if you get caught and be prepared to go around. Link to comment Share on other sites More sharing options...
Seal Posted December 25, 2008 Share Posted December 25, 2008 Getting back to the gust thing. It's a pretty much data free observation, but my feeling would be that gusts can be sharper edged than lulls. Also, when approaching downwind, wind shear effects are airspeed positive rather than the normal airspeed negative so that works in your favour. I wonder what the strip is like when you are landing into wind up hill. That ridge in the background must produce some interesting turbulence. Link to comment Share on other sites More sharing options...
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