Typically I use the landing gear so it's almost where the CoG is, with a front wheel setup. I've had a few issues with it in general, mainly that the airplane is much too light to flare it much for landing - it stalls too early to flare.
So I'm trying to come up with a way to have the front wheel touch down a little later. The obvious solution would be to shorten the front wheel's support. I'm a bit worried that this will cause trouble when taking off. I've got a few ideas on how to alleviate that, but why experiment when there's so many knowledgeable people here? :)
So the question: How would you set up the landing gear in that case?
For tricycle setups, put the main gear far enough back, so when it is in climbing attitude, the weight is just slightly in front of the main gear. In other words, with the tail all the way on the ground, it should settle back down on the nose gear when you let the tail go. Just barely, though.
For the nose gear, set the length so that the wing has about a 2 degree down angle, from a line at the leading edge, to the trailing edge, at a maximum. Some people like to set the nose length so that the wing angle is up a couple degrees, but if you like to shoot a lot of touch and go's, you could accidentally hit the nose gear before the mains, and that can lead to a really bad looking landing at best, and at worst, a bent nose gear and or torn out firewall.
If your nosegear is slightly short, the wings will be in a non-flying angle of attack when taxiing. This has some advantages. The plane will have a very well defined separation between taxiing and flying. On the takeoff run you can run it up to a very high speed, then bump the elevator just a little and the plane leaps off the ground. When landing you can perform a beautiful flare and stall, and when the plane hits the ground it sticks like a brick (and has the grace and beauty of a brick). Then you can taxi it back to the pits as fast as you want to and it never wants to float.
Setting the nosegear up at a positive angle of attack will make the plane touchy and sensitive in all of these characteristics. Making it neutral (meaning that your wings are at the minimum angle of attack for flying while the plane is on its wheels) will give you a plane that will still be capable of performing very graceful takeoffs and landings without ballooning or plopping.
Now to address your question, I'm not sure I understand exactly what you're asking, and I think it may have something to do with the definition of the word "flare". When I say flare I mean that the plane is in its final approach, it reaches ground effect, and it floats along just above the ground while losing speed. Once it starts to sink again, you feed in up elevator until the nose comes up a bit and it stalls, then touches the ground. But perhaps you were referring to the classic Air Force flare, where they land the fighter planes nose high with power on and roll on the main gear for a few hundred yards before the nose drops, so they can abort the landing if they need to. We had an old Air Force colonel in my home town who used to train all of the new guys to land their Kadet and PT-40 trainers Air Force style. It looked completely unnatural.
In any case, you might enjoy having your nosegear a little shorter when you set up a new plane. It's like putting training wheels on your bike. It takes a few variables out of landing so everything is more predictable, but it makes the plane look a lot less graceful. Then once you get used to that particular plane you can start lengthening the nosegear little by little to make it act more like a real plane. You'll eventually learn how to set it up in the middle ground between bouncy and bricklike, so you can enjoy watching the beauty of a well executed landing without the "training wheel effect" sucking all the graceful fluidity out of it.
Touch and go landings are my favorite thing to do with an RC plane, and you have to have the landing gear on a trike plane set just right to experience the full beauty of the touch and go. Too much nose-up and it will bounce and buck. Too much nose-down and it plops like a blob of mashed potatoes.
Trying to figure this: The airplane is so light that it stalls early? Sounds like it's either heavy and you're getting too slow to have anything left to flare with, or the CG is too far forward and the elevator is losing authority on landing and the nose drops. Or do you mean that the controls are light or touchy?
Neither. Sorry, my native language isn't english so I probably didn't word it properly. What happens is this: It floats so much that it's impossible to flare for me. The flare "window" is very, very, VERY narrow. Slightly too fast and the plane just climbs again. Just a wink below that speed the plane stalls even on level flight. Maybe it helps if I add that it's a delta wing, which generally has a lot of its wing area waaaaaay aft. CoG is, as near as I can tell from the flight characteristics, spot on. Nose does of course drop on stall, after all there isn't much wing area in front. Controls are dual rate btw, I use low rates for takeoff and landing.
AAhhhhhh! You bet it helps, saying that it is a delta wing.
First, CG should be at around 15% of the wing area. To find that, you put a mark at 15% on the wing tip, and another mark at 15% at the wing root. Draw a line connecting the two marks. Along that line, measure one half of the span on the one side of the wing. That point is your 15% CG mark, on which it should balance.
As far as the flare, there are two ways to land a delta wing. One, is to basically fly it onto the ground without flaring, with a good measure above stall speed, perhaps 10% to 20% above stall speed. If it is too hard to judge, just pick a speed where you don't have to lift up the nose (hardly at all) to maintain level flight. Drive it onto the ground with the right power to give it a small sink rate, and when it hits the ground, chop the power.
The second way, is much more difficult, and also the way many full sized delta wing airplanes land. (because of slower speed at touchdown) To do that, while you are a long way out on final approach, is to stabilize your speed and power to get a very nose high attitude, with a small sink rate. Then you have to get it into your head that the power is what controls how fast you are descending, and the nose attitude controls the airplane's speed. Just backwards from cruse flying. I find it very hard to get that whole thing in my head.
When you are trying to flare with your delta wing, by raising the nose, you are slowing the plane, but you have enough extra speed, that it has not gotten backwards on the controls (like I just explained) so the extra speed makes extra lift, and you go up.
So, if you want a flare, you need to start your flare, way out, and way high, then use the power to get your speed under control. If your flare causes you to go higher, then slow the engine, to get your speed down, and then start using the throttle to control your sink rate. Lift the nose higher to slow down, after you get slow enough to have the engine control the sink rate, and as you get closer to touchdown, keep raising the nose to get slower.
Complicated? You bet! My usual strategy is to fly it onto the ground.
Ooops. Sorry guys. I like mine btw, it's fun. My only complaint: the flight times are a bit short (~20 minutes per charge, 10 minutes if I fly full throttle).
20 mins might not be bad per se, but I don't have enough battery packs to just swap and keep flying forever... with glow you just refuel and take off again. Then again, with glow I can't just walk over to the nearest park and fly, I'd have to drive 30 mins or so to the closest RC airfield. Plus... I'm absolutely lousy with combustion engines. ~laughs~
I currently live in the Salt Lake area :) Born and raised in Europe, relocated in early 2001. Thanks to my job I've had lots of language practice, but specialized vocabulary (groceries, plant names, R/C terminology just to name a few) I'm still a bit lost at times - especially since common dictionaries often don't have the translations for that kind of vocabulary either :)
You have not found the right combustion engine, with the right installation, if you are lousy with them.
My best running, no fuss glow engine is an OS FX .15, which is unfortunately not made any longer. You could probably find a used one, or perhaps a new one, but many other OS engines work just as painlessly.
This engine is on a Clarence Lazy Bee. It is a lot of engine for this little plane, and I dare say that you would not have to drive to a field to fly it. It is truly a park flyer.
Because it is so over powered, it seldom is at full power. Added to that, I used a 4 ounce fuel tank instead of the recommended 2 ounce fuel tank. At low power, it will comfortably run for 30 minutes, or more.
Running this is a matter of putting some fuel in the tank, attaching the glow igniter, turning it with an electric starter, and plugging the muffler outlet briefly to prime it. It usually starts within 3 seconds. After it starts, I let it warm up for a few seconds more, then take off the glow igniter, test it briefly at full power, low power, set the low idle trim, rev it up and down a couple of times to make sure that it is taking the added power transition, then idle it back, and take off.
No needle fiddling and tweaking, except sometimes for the first flight of the day, to take into account the seasonal temperature and humidity changes. After that, on similar days, I test the response to the power changes, and decide that it is good, and fly away. It is amazing, and sometimes scary, how rock solid dependable it is.
So really, it is possible to get such a good running glow set-up, that even a "dumb electric pilot" can fly one!
See, my first airplane experience was a glow engine. OS MAX FP 25. I still have the engine sitting right next to me as I type this... it ran, no doubt. But getting it to run properly always took me ages.
I vividly remember the day I flew with a friend who had marginally more experience with glow engines, and he set the thing up within maybe a minute. It took me about 5 mins each time to figure out where to dial and what to do to get it to run properly. Despite my dad patiently trying to explain to me what does what and so on. On an intellectual level I know how it all works. But there's that HUGE difference between theory and practice :)
Admittedly as I know now I made plenty of mistakes with it, but I got spoiled rotten with the electric setup: Plug the battery in, do pre-flight checks, take off. And of course the park availability issue. It's not necessarily the noise - it's simply that most parks in the area point blank do not allow combustion engines of any kind on the grounds, including R/C vehicles.
Another thing that would probably make it difficult for me is that I fly in the valley (at around 5400 feet ASL) and at my workplace in the mountains (at between 8000 and 9000 feet ASL) - electric doesn't care, combustion on the other hand does as far as someone at the LHS explained to me once.
All in all I'm just terribly happy with this hobby. It's fun, can be exciting or very relaxing, and it is a nice contrast to my everyday work.
Of course, having this great newsgroup helps a lot :) Just reading along teaches me new things. The volume is just low enough and the topics much more interesting to me than the various forums. I'm biased, what can I say :)
Wow. Take the airplane along sometime and fly down near sea level, and find out how much slower the airplane will fly due to the much higher air density. The low density at your altitude requires a lot more speed to support the airplane, as well as hurting the engine's performance. And a warm day at 5400' could mean a density altitude of 7500' or more, as the warm air thins out. That's why most modelers find improved performance on cold days.
I'm aware of the performance differences :) My point is that I don't need to tune anything - I just power up and fly. The speed differences are indeed dramatic, as are the performance differences, heat/cooling issues and all that. A good example: I tried flying an original Parkzone F27B Stryker (RTF) up there once. It didn't have enough power to climb at all. That was, btw, on a bitter cold winter day.
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.