acdii

Flew my P-51 last night, it was it's third flight and discovered at landing speeds it has VERY little rudder input. I fly a lot of rudder with my LT-40 and 4*120, especially the 120 on high crosswind days, it usually comes in at a 45* angle to the runway with releasing the rudder just as it touches down, and last night there was a cross wind that kept pushing the Stang to my left as I was trying to land it, and there was NO visible effect of rudder. First attempt was too far south, so powered up and went around, second attempt was right down the middle but too high, didn't want to chance going off the end, so went around again. Third attempt got pushed much further south and I had full left rudder into it trying to cab it, and no effect. I hit the throttle and saw it was going t get too close to the tree behind me, and I must have pulled back too fast as it had snapped over on its back and performed a perfect half circle, but the ground got in its way. Two more feet in altitude and it would have cleared. It hit on the bottom of the cowl and snapped the fuse in half at the instrument panel. The landing gear got ripped out since they were down, and the flap servos, one needs new gears, the other broke the mounts off the plate and the same happened to the aileron servos, so need new gear sets for at least two of those along with one for the throttle servo.

So removed the wheel wells, they are undamaged, removed the gear, looks like they are OK, still straight too. will need to do some minor repairs to the wing where the gear mounts go, leading edges are OK, only busted a few ribs and the mounting blocks.

The Fuse busted clean in half, so might be able to just splice it back together and reglue all the formers. The only damaged former is the one for the wing dowels. Then I just have to recover it.




I might be able to salvage the cowl, it got crunched up, but some epoxy and light cloth should fix it up, then sand and repaint it. The spinner got bent, might be able to repair it, if not I have another one for the kit build. The engine is packed with soil, so will need to clean it up, but nothing got damaged, and it still turns nicely. I have to figure out what is up with the rudder though, I should have had more control with it that it had. Even at cruise speed it has little effect, I should at least see some yaw when I move it, but I dont. It also seems to have little effect on take off too, the plane goes left on take off, and I had the rudder quite a ways right. It is setup with the proper throws, no expo, and no rates. The one thing none of my planes have is expo and rates on the rudder. Last time I flew my LT-40 prior to last night, the aileron servo lead got pulled out of the RX by the throttle servo(since corrected) so I had no ailerons, but brought it in on rudder only, which was a challenge since the rudder sticks a bit and needs opposite touch to straighten out. When rudder input has very little effect on flight its a bit concerning.

Villa

Hi acdii
It looks like you are having a great time in our hobby. It took me a long time to learn why I was crashing during the landing attempt. Here is what I learned and decided to follow: After you study that I would appreciated your comments.
After I realizedI was having many crashes due to stalling during the landing, I did some heavystudying of what was happening. I was mainly crashing when I was landing at anangle to the left/right of the runway due to a cross wind. Since normal depthperception is only about 17 feet, and I always landed further than 17 feetaway, I suddenly realized that when I landed at an angle I did not know wherethe plane was in height, relative to the runway, since I did not know how faraway it was. In addition, when I land at an angle, I completely lose my senseof "rate of decent" (I don't know how fast/slow I am approaching theground). Furthermore, with the plane coming in at an angle, I completely losemy sense of ground speed of the plane. I addition, coming in at anglecompletely destroys my sense of "angle of flare" because of thegeometry of what I am seeing. I searched for a solution and this is what I donow: I only land right-to-left or left-to-right. If the crosswind is terrible Iwill point the nose a little into the wind. On every landing, I do my best totouch down directly in front of me as I am facing directly across the runway(at a right angle to the runway length). By landing in front of me, I have abetter and constant view of the plane attitude, ground speed, rate of decent,and flare angle. For those that wish to point out that the plane cares nothingabout ground speed, only air speed, I point out that we fly our planes withoutthe instrumentation to know air speed, and instead substitute other input toarrive at a safe landing.

acdii

Landing isnt a problem once I get the plane lined up, still having some timing issues on the flare just before the wheels touch though. The problem I had was lack of rudder authority, which is what I was depending on the bring the plane in with. I fly it with the tail and just use ailerons for keeping the wings level when landing, so when there is little to no rudder it makes it harder to line up. This is my first warbird, so not sure if the lack of control is normal, or if something just isn't right with the tail. I had the throws setup per the book too. I can understand the dorky up elevator, thats just a quirk of this particular plane, and the reason I crashed it, really had nothing to do with the actual landing, just the go around attempt that I am so used to being able to do with my other planes bit me in the arse on this one.

rt3232

My Feedback: (6)

Acdii

I don't want to muddy the water, but both of my big T/F P-47 and Corsair I have great rudder authority even at 2clicks above idle, I have never had a stang, so can't be of much help, but I have learned to line up as best as possible and keep the up wind wing down about 10 to 15 deg's along with a steep final to get down to ground effect and then wings level and pull the power off. Our main runway is only 750 X 100 but grass bleeds off speed really well.

Good luck with the repair, and hope the above helps

Cheers Bob T
AMA13377 Corsair Brotherhood #6

Charlie P.

The infamous Figure 9.

Note that "landing speed" on a P-51 of any size is half throttle. The rudder yaws the nose to one side and the tail in the opposite without much heading change on models without much dihedral. You have to use all three axis controls and monitor throttle. And if you were to ignore one successfully it would be the rudder.


With warbirds speed is life and it's about energy management. Keep the airflow smooth to keep control.

acdii

There was zero yaw at just below half throttle, thats where the problem occurred, but the thing that brought it down was overreacting to the upcoming tree and pulling up instead of banking to the left and going north. I really didn't have an issue landing it, the issue was keeping it lined up with a cross wind. Going to take more practice and less pulling back on the stick. The first two flights I was able to land it just fine, putting it right where I wanted it, except for hitting the unseen gopher hole and flipping it over, plane was already on the ground, tail down, then blip, over it went. I may just increase my rudder throw once I get it back together.

BTW my flying field is about 60' by 400' with farm land on three sides, so a short or long landing is not a good thing, go long and its in the dirt on its back, go short and play pick up sticks with whats left. I have learned precision landing with all my planes so far, this was the first one that is lacking the control I am so used to with all of them, including the Twin Otter. Thats my only trike and I have yet got the thing to land softly. I usually slam it down as if it were landing on a carrier deck.

smithcreek

My Feedback: (25)

I don't understand how you are using the rudder. Sounds like you are using it to increase the angle that the plane is crabbing in relation to the runway, then letting it straighten right before landing? Sounds like the opposite of slipping it in.

acdii

Thats how I land all my other planes, by crabbing it in. Especially the 4*120, that big lab side plane gets pushed hard by a cross wind so the best method I found to keep it lined up is the crab it in. I also fly off a very narrow landing strip, with farm land on 3 sides and buildings and other obstacles on the other. Precision landing is a must and when the field is corn, you come in high and drop it down at the last moment. The strip is only about 50' wide by maybe 250' long. It can be a real challenge when trying to land a floater. At the other field I fly at, the only obstacle I have is the left side of the runway ends in a ditch that is rather deep and the land on the other side is about 10' lower, so landing can be tricky at times due to the optical illusion that you are at the right height, when you are actually a little low and clip the grass at the edge when landing. I have put my plane in that ditch twice now, once from a dead stick on a go around, and once due to coming in too low. Neither resulted in any damage to the plane just my ego.

If there is a different method to landing this type of plane in a cross wind, I'm all for it, but for my other planes rudder works best for me, especially that one time my aileron lead came unplugged from the RX. Rudder was the only thing that brought it in for a safe landing. Thankfully the servo was at the neutral position when it came out.

smithcreek

My Feedback: (25)

If I'm understanding you, say the wind is coming from behind, pushing the plane away from you, you are using the rudder to point the nose of the plane towards you. If that is correct then side slipping would kind of be the opposite since you would be using an opposite rudder input.

The 4*120 would be a great plane to practice the side slip on. I used my 4*60 for it. I learned by picking a day with the crosswind coming from my back. Got the plane very high lined up for a landing. Cut the throttle, then tilt the wing so the close wing is low, like 30 degrees and gave full low rate rudder to turn the plane away from you (kind of like doing a knife edge). Leaving full rudder, use the ailerons to keep the wings angled and the elevator to keep it lined up with the runway. The plane should drop like a rock compared to floating it in. The rudder is creating a huge amount of drag and keeping the plane in line with the runway instead of crabbing. Eventually you can fly it down to just a couple feet off the runway before leveling the wings.

Here's a vid of a full scale. The way he's doing it would be exactly as described with the wind coming from the right side of the plane. Dip the wing on the side the wind is coming from, in this case the right, kick hard opposite rudder, in this case left. Then use elevator to line up the runway.

Side slipping a warbird though is tough. I would not do it nearly as much, just a slight side slip to help keep it lined up, not a severe one to create lots of drag.

https://www.youtube.com/watch?v=evgsfgpT-7w

acdii

Oh OK I was sort of doing that today with my 120. Wind was at my back and I was bringing it in with the left wing down, Flying right to left as it was a SW wind. When I dug a hole the wind was at my face and pushed the plane behind me, there is a tree directly behind me and the plane was tracking towards it, which was what made me want to pull up instead of turn it. At least I can give this technique a try once the plane is airworthy again. I started the repairs today, have the fuse stitched back together so it is whole again, the formers are repaired and reinstalled, have a few more small pieces to put back then I can scarf in some sheeting to bridge where it cracked along with some stiffeners, then hit it all with Medium CA and Epoxy, then a light sanding and covering and good as new.



The wing I started pulling the broken sheeting out, left wing is just damaged on the bottom, and all ribs are intact, right wing rib 1 is pretty much gone, so I will have to dig through my kit to find the template for that rib, shouldn't be too much difference between kit and ARF. Glued together 2 pieces of hardwood to match the forward gear block width, and once cured can cut out two new ones, and have larger block for the aft gear block, the right wing got top skin damage so that will take a bit more work. I dont see more than a few hours work to get it back together, including covering. I'll get some pics of that next time I work on it, I didn't have my phone with me.

Villa

Hi acdii
During our landings with RC planes, there is a very complex amount of geometry going on. The explanation I gave above covers this complexity, but I don't believe many people take the time to understand what is going on. I have had only one or two people agree with me, yet the geometry and the limitations of our depth perception is right in front of us.

acdii

No doubt. Sunday I was flying with a SW wind, mostly S, so landing was almost directly towards me. It was hard to determine, airspeed, height and distance. Made for some interesting landings. Had to keep the speed up on landing too or the wind could flip or toss it when it got to the ground. Once I get this one back in flying condition I will work on my landings a bit more and try not to fly with too much cross winds until I know how well it handles on landings. The first two were into the wind, and were really good soft ones(until the right gear caught a mole hole). Nice nearly perfect 3 pointers, nose up, tail just about on the ground when the mains touched, but quickly dropped down once they did. First had a good roll out and taxied it back to the pit, the second hit an unseen hole and flipped over on its back, in slow motion too. I know I hit a hole as the right gear was bent back slightly. It had also been down for a couple feet before it did.

rt3232

My Feedback: (6)

Villa

Been flying RC sence the home built radio era, and you are SO right about the depth perception thingy as I have been there and done that. it would be great if some of our experts would just come up with a speed squawker that could be a stand alone and adjustable say from 40 mph to 100 mph for our models, and reasonable $$$ so we would not have to go to the Hi $$ radios. It would save a lot of nice planes


Cheers Bob T

Villa

Hi rt3232
Most of our club members still believe they can determine what is further away; a tree or their plane, hundreds of yards away. They have the same experience I have, yet they keep believing that the human depth perceptions is limitless. It is only about 17 feet!

acdii

Even less when wearing Trifocal progressives. The one thing I look for is a shadow on the ground, when I see it touch the field I know I have cleared it, problem is most times I am still too high to land easily and go long. Whats funny is prior to my last flight I was flying my LT-40 and did 10 T&G and put it right in front of me every time. With the SAME crosswinds, though the rudder on that plane actually makes it yaw.

Charlie P.

Hmmmmmm. 17 feet? That seems overly short. I shoot traditional (sightless) bows and the field archery course involves targets out to 80 yards. I also stump shoot to the same ranges - where targets are of unknown size and distance. I can judge yardage fairly well out to that distance from practice, practice, practice (I shoot my bow daily).

But that's with time to think about it and move side-to-side. Motion makes a big difference in judging distance - watch a perched owl line up a mouse. They move their head in a circle and just that slight motion improves depth perception. The further the target the less affected by the observer's motion.

But yes, I have smacked trees. When your are focused on the model you lose track of the peripheral features.

rt3232

My Feedback: (6)

Charlie P

Make no difference shooting a arrow's, clay pigeon's shooting landings, the key is PRACTICE, PRACTICE, PRACTICE. The other thing is to move your head from side to side, I have also smacked trees from starring at the plane, and lost the peripheral thingy, but trees some times have long arms, or they can grow a foot or two almost instantly

The other thing to get good at landings, when possible change the size and wing loading, it will give you a new perspective.

Just my thoughts

Cheers Bob T

acdii

Try landing a Twin Otter with one engine. That skinny ass wing can make that plane fall out of the sky rather quickly. Now that is a plane I have to practice flares on, seems I slam it down like a carrier landing every time.

jetmech05

I'm no expert but I fly in crosswinds too. If the cross wind is at my back I go a little long on my base leg. If it's in my face I go short on the base leg. Either way I'm letting the cross wind blow the aircraft to center line. I don't fight the crab I just "kick" it out just before touchdown.
Remember that altitude is controlled by throttle and speed is controlled elevator. Give it a try

acdii

I know how to land a plane, especially in a cross wind. Keep in mind this was only my third flight with a warbird. Techniques that I have been using to land in crosswinds did not work with this one, I just dumb thumbed it on the go around. My second go around was right on the money, but too high, I was practicing the approaches, getting the feel of what the limits were when I pulled back too quick on power up. I do know this plane lands a lot easier than my 4*120, I just have to work on the approach without using rudder now.

Back to the rebuild, I cleaned my engine the other day and found the case was cracked from the crash. A new case and bearings are being delivered today so I can rebuild the engine, then recover the plane and reassemble it.

jetmech05

Didn't mean to offend

acdii

No problem, it just seems that all the posts are like, you cant fly. Gets a little old after a while. I mean it is a rebuild thread, not a what did I do wrong thread. I know what I did wrong, now to fix the damage and not do it again, at least not so low to the ground.

FlyerInOKC

My Feedback: (6)

Hey at least she'll live to fly again with a little TLC!

VeeAte

Ouch.
Sorry to hear she went in.

I have flown a fair few warbirds and I learnt early on to ignore the throws specified for the rudder.
Nearly every plane I have I run full travel on the rudder with only a small amount of expo. Especially the warbirds. I dont run dual rates on the rudder.

One thing I do remember about my P-51 was that it would drop airspeed VERY quickly if you crossed the ailerons and rudder up coming in to land. I always kept half throttle until I crossed the threshold and then slowly drop the power to get a nice sink rate.

Yours having no rudder auth at half engine speed would make me think there was an issue with the servo or the control setup.
When you rebuild it swap the rudder servo out and see if it helps. Also check there isn't any binding in the control rods or pull pull setup.

And set the rudder to give you full throw. If this makes it touchy on the rudder add a small amount of expo to soften it.

Not trying to judge what happened or your flying skills.
I am glad you will have her sorted soon

raptureboy

Agreed on the rudder authority. Dial in as much as you can because it is a very small rudder. I have also found that when using the flaps you need more elevator throw as the flaps blank out the the elv authority so I switch to high rates for landing. Sorry to see such damage but you are really doing a good job on the rebuild and asking all the right questions.