My EZ p-51 .45 model flies fine but when I bring it in to land it wants to nosedive into the asphalt. I'm pretty sure there might be too much weight in the nose. Has anyone experienced this, where a plane seems to fly just fine, but when brought to land it tries no nosedive?
Joel
No slam but I don't know your experience.
Do you slow down adequately so as to round out roperly? Do you get just off the ground about a foot in a slightly nose high attitude and continue to increase back pressure as it slows, nose higher and higher and slowly settles in? OTOH are you getting too slow too high and losing pitch control?
Many people have a tough time maintaining heading and holding the nose up at the same time. IMO and as a long time instructor (RC and rider-scale jets) I find that many RC pilots just allow the elevator to slide back to neutral if they have to use the ailerons too, during the final phase of landings. Nose DROPS. The CG would have to be somewhere around 10-15% of MAC to be unable to hold the nose up of the average RC, even at landing speed. Otoh one can get so much UP-elavator and really nose high, that the entire stabilizer will stall out also allowing the nose to drop rapidly.allowing the I thiiinnnnkk!
HC
Check that you don't have a lot of toe in or toe out on the wheels. Also make sure that the wheels turn freely.
After that, when yo land, you need to do a proper flare asn the plane touches down so that you keep the nose up. Once on the ground, you should keep just a little up elevator until the tail wheel will stay on the ground with the elevator at neutral.
I have built and raced several of these planes usually with an OS .91 Surpass and 40% nitro. It is one of the best handling warbird ARTFs I have ever flown.
Just a couple items to be aware of. Soak the landing gear mounts (ply inside the wing) with UFO CA. These are just light ply pieces and will start to deteriorate after a few dozen landings. Also, in the rear half of the fuselage, the balsa inside the foam covering is very weak. If you look inside, you will see where you can add some 1/4" triangle stock to the flat balsa stringers (for lack of better name). The rear structure is like a box fuselage with no top or bottom sheets and large cutouts in the sides. Glue these on so the hypotneuse (SP) section of the tri stock is against the wood. Go the full length of the rear pieces. Use a good bit of aliphatic resin on these pieces. I had two break off on dorked landings.
Most likely getting too slow and stalling the wing. Don't hold it off so long. Other possibility is too much up-elevator travel, which can stall stabilizer/elevator before the wing, as suggested above. Max up elevator travel should be around 25° (on low rate).
Robin
He says it flies fine so the CG is probably OK or at least close. All else working fine other than wanting to eat dirt on landing, I'd say the landing gear needs to be moved forward maybe 1/2". The go fly and get back to us.
MJC
If it flies OK the C of G can't be too far out so I doubt that it is too noise heavey.
Do you mean before touch down or after?
If before lift the nose with a gentle blip of throttle before you touch down and fly it onto the ground. IE. don't just let it glide onto the ground at idle revs.
If after, give it up elevator whilst rolling out on the ground. Also bigger main wheels might help.
Nick
Are you talking when the wheels are on the ground or before touch down?
Yeep. I have flown teh simulated version on G2, and its the hardest to land decently. Especially with flaps. It needs power to control the descent, and very acurate flaring, otherwise it bounces or tips over.
No idea how realistic it is, but if a buddy has G2, its maybe worth practicing with it a bit.
The EZ-P-51s I have built and flown do not have flaps or provisions for them. Are you maybe flying the TF P-51?
I'm talking right before I touch down on landing. I will pull with max elevator and it will still nosedive. And it doesn't seem like a stall either. It's weird. I've landed p-51's before and it just seems like they are the most difficult to land properly. P-47's are a piece of cake.
It sounds to me like you're getting it too slow. Maybe the reason it doesn't look like a stall is because it's already so close to the ground there's no time for the traditional, obvious characteristics.
I'd try bringing it in a little hotter. Especially if you don't have/use flaps. The real Mustang wants flaps on landing and properly set up, they turn a tiger into a pussycat. But without them, you have to come in hotter than expected and make a wheels landing on the mains. Then let the tail drop as speed decreases. Takes practice but once you have it, it's easy to do.
You are stalling it and very lucky that it is probably slightly nose heavy. Otherwise, you would have really banged up wing tips.
Come in with a click or two extra throttle and let it off just before you touch down. Keep a little up elevator in it as you touch down.
Moving CG back is a poor substitute for fixing the stabilizer stall, if the CG is where it is supposed to be. As my son suggested earlier in this thread, the elevator travel needs to be checked and brought within limits, if it's out. Too much up elevator can stall the tail and make the nose drop. You can't add travel and expect the tail to keep responding, any more than you can keep raising the nose and expect the airplane to keep flying. In full-scale, there are specs for every control surface travel, and they are given with tolerances of one degree or less. There are reasons for that...
Dan
Hi Joel,
All those guys are over analyzing. The damned thing's noseheavy. Move the CG back a tad. I've had it happen on high performance models many times.
Cheers,
CR
Joel wrote:
I think you're over simplifying. You assume that nosing over on landing is a consequence of forward CG but CG placement and the sympton of nosing over are completely unrelated. Deciding whether your CG is right or not based on eating some dirt on landing will get you in trouble every time. What he needs to do FIRST is to determine if his CG is good, but you do that by FLYING the model, NOT landing it. You fly it through turns (high and low speed) and do stalls all the while OBSERVING the aircraft's flight characteristics. Any experienced flyer can tell him what to look for when doing those manuevers. AFTER the CG is made right, THEN he observes what's going on during the flair and rollout. If the problem WAS the CG, then it will rollout fine. If it still noses over, then gear placement is the problem. There is a logical order for trimming out a model for all phases of flight (all the way up to rollout on landing) and deciding that the CG is wrong just because it noses over on landing leaps over several logical steps. Yes, an improper aft CG is one reason that an airplane won't rollout without nosing over, but there are other reasons that should be considered first.
MJC
"Charles & Peggy Robinson" wrote in message news: snipped-for-privacy@ktc.com...
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Gear placement is critical on the WWII models! While holding the plane level, sight straight down at the leading edge of the wing. The axle (not the front of the wheel) should just barely be visible. Using this formula, most nose overs can be avoided.
He said it nose DIVES, not noses over. The CG is too far forward.
CR
MJC wrote:
I'm surprised that the plane doesn't tip stall when you yank full back on the elevator like that at such a low speed.
You're probably used to a stall where the plane pitches up sharply, then falls off. The plane doesn't have to be pitched up sharply to stall. All it has to do is slow down until the lift from the wings is less than the weight of the plane.
Despite what many people are saying in this thread, your plane may not be nose heavy, and moving the CG back may make things worse!!! Instead of nose diving, the plane could end up flipping over on its back and crashing (tip stall).
There are some in-flight checks you can make to determine if the plane is nose heavy or tail heavy. GreatPlanes.com has a "trim chart" with numerous tests for trimming a plane out beyond making it fly straight and level.
One test I remember is the "inverted test." Trim the plane for level flight, then roll it inverted. If the plane dives more than a little bit, it's nose heavy.
Pay attention. The elevator up travel needs checking. Big, effective stab or not, CG in the right place or not, if the elevator is traveling up too far the stab WILL stall and the nose WILL drop. The plans should give a travel range and it needs to be heeded. This is not an unknown problem, and certified full-scale airplanes have encountered it. The Cessna Cardinal had the problem with its early stabilator, and other aircraft have experienced it as well. Results in busted airplanes.
Dan
It'll nose dive a bunch if the CG is in the right place and you invert it. The stabilizer pushes down in normal flight to counter the CG's location forward of the centre of lift; this is called static stability. Inverting the airplane also inverts the tail, and the stab will lift the tail and lower the nose. Significant forward elevator should be necessary to maintain level flight when inverted.
Dan
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