Hi All,
I have a Bobcat composite / P-70 that has probably 40 flights on it. at first, landing the plane was a non-issue, but in the last month or so it seems that I cant seem to land a 'greaser' 1 out of 4 times!!
what always happens is what looks like a perfect base and final, followed by a nice flare on the mains, only to end up with the plane doing the death bounce from nose gear to mains a few times till the flex plates give way. no other dammage except my pride.
the only thing I can think of is that im trying to keep it flying too long, or im trying to 3-point it like a tail dragger - imac plane.
one thought was to quickly switch it out of crow the second it lands to kill all lift, but im not sure on that one...more worried about my slow fingers.

plane is set up per bvm including all throws, crow modes, etc.

thanks in advance, Kirk

Something changed, any idea what it was? I just hold up elevator in mine until the speed bleeds off and it comes in perfect. My Kingcat on the other hand does have a tendency to bounce so I need to keep more up in it for longer once its on the ground.

Kirk,

The bounce is caused by touching down too fast and with the nose not being high enough. You need to hold it off with back stick until it touches down on the mains only. I guarantee that if you don't touch down util the stick is all the way back and on the mains only, you won't bounce. The Kingcat/Bobcat is actually a bit tricky to get exactly right, but when you do, it will help you landing other jets.

If you do get a bounce, the only time you can stop it is on the first one. After the first bounce, you HAVE to keep the back pressure on and hold it off until it looses flying speed. If you don't catch it on the first bounce, then after that, you're just along for the ride...

When flying a Kingcat, I snap off the flaps as soon as I'm sure its down - it seems to help a bit in keeping it from skidding when you apply the brakes...

Bob

Kirk,
Follow Bob Klenke's advice. Are you using the crow setup?
Definately hold the plane off so has stopped flying when it touches down.
I've also found that if you preset the brakes that when you touch down the nose will stay stuck down.
Be sure to grease the brakes so the wheels don't lock up.
Bob

Air speed at touch down is the biggest factor. In addition to the previous suggestions, you might also look at the CG. It seemed to me that the tendency for my Bcat to bounce was reduced when I moved the CG back about 1/2" from the BVM recommended setting. Can't prove it, but I think the more rearward CG reduces the tendency for the nose gear to rapidly compress then rebound when the mains touch down. When the nose gear rebounds, it increases the angle of attach of the wing and the Bcat takes to the air again. As always, changes in CG should be in small increments. Good luck.

I find it that a bouncing happens when the elevator is relaxed. Yup, you think you got the run way, you flare touch down and relax on the elevator. Then follows the death bounce .

Even after touch down don't relax the elevator. Maybe now that you've flown it enough, you are coming in with more speed (?) knowing that it will slow down. Try to pull a wheelie after touching down the mains.

I would advise not to change the crow/flap settings as you want to continue bleeding airspeed and lift through your roll out. Crow will kill lift.

I recently increased my KC flaps to 45 degrees and 1 inch [X(] of crow. Now she finally slows down nicely with a short approach.

Remember to hold that elevator!

Raf

You can also turn the flaps off once your wheels have touch the ground. This relates back to the plane still "flying" at landing time. Turning off the flaps reduces the lift and makes the plane stick to the ground like glue.

The only problem is, if you need a go around....you might need that extra lift.

I'ts a BVM just get used to the bouncing and stock up on flex plates. [:@]

I'm gonna regret this but...

I've only replaced one set of Bandit plates after well over 300 total BVM(SBB x1, BARF X2, Kingcat x1!) flights!

Yes, I'd like a pat on the back, a cookie and a boy scout badge!

Raf

You don't help the model industry at that rate. BV is going to start making them softer then!

My friend has a KC and i would call it "flex plate monday" because he would be calling BVM every monday for new ones... ha
V..

Ha, I just got a call from the NASA guys I work with asking me if I'd be willing to fix the flex plates in one of their KingCats and the associated airframe damage... You gotta' get those things SLOW and NOSE HIGH before you let them touch down! More hours (i.e., plane money) for me though...

Bob

Are you guys not doubling the mains on your KC's?

Raf

Hey Kirk, looks like Bob already got the answer, I always tell guys to make sure when they're about to touch down, never have the nose wheel hit first, if you do, you're going for a ride.

I flew the Jet A1 KingCat main struts with a customer, and lets just say we "thoroughly tested" them! I about dropped the TX when I went over to inspect the damage - not even a flex plate was cracked! The plane had almost cart-wheeled! It was pretty amazing, and Todd @ Dreamworks has them in imperial sizing (Prolinks). I'd get em for the BC's, KC's and Bandit ARF's. Sooner or later they'll pay for themselves! Just keep some spare springs in your box.

Land with the gear up. It won't Bounce!

Now that is hilarious.

I had to dead stick mine in rough grass once, and it did not bounce, not even once. No damage at all - but I did remember to pull the flaps up just before touch down.

Easy!!! Pre-set your brakes and it will NOT bounce period!!

'Tis true, but its tough on tires!

Bob

After flying the kangaroo now for about 2 years or so (my only jet) I have learned the hard way to keep it from bouncing. All of the guys have given you all of the right information to stop the bounce. I believe speed is the first problem. 2nd... What I tend to see is alot of guys come in on final with the nose slight down (3 or 4 degrees) and then flare when they get close to runway and try to relax the up elevator to get it to touch down. This approach tends to hold a constant speed ( even with the BARN DOOR DEPLOYED). That dam kangaroo will float forever on approaches like that. I can hold up elevator for what seems like 5-8 seconds before it bleeds enough speed to come down on its own, on the mains, and not bounce. Which in turn eats up a ton of runway. Instead of learning to land it right, I got to the point to where I was flaring before I was above the runway knowing the ROO would float for a while before bleeding off enough speed. FINALLY I had a local JET GUY stand with me on the runway and walk me through properly landing the roo. My biggest problem was on final and letting the nose have a slight down ward attack at the runway. He advised to at least hold the jet level if not 1-2 degrees up and let the jet start bleeding off speed. WOW what a difference that made. The roo slows down really nice now, when I flare, it doesn require me to hold for what seems like an eternity, and I only chew up about 200-300 ft of runway after touch down. Hope this helps you some.


Sean

You may also cheat by using trailing link struds on the mains. This would put your mains further behind the CG.


JasonP

Also check your CG. If its to nose heavy it won't land very nice either. Hey David how bout some pictures of that new Lil'Sshui! Can't wait to see that little eatin,sleepin pooping machine!! Fla. Jets maybe???
Tim.

to make you up to date:
we got plenty of drop in sets like the ones you had from me David.
because i knew about the customers practicing we now give a set of springs for free with every purchase..

Yep, we pre-set brakes about 1/2 up here at altitude / short runways.. I'm on my third set of tires. Oh well....
Lee

My first turbine jet was a Kangaroo and 300' hard surface home field. @ 17lb dry and a AMT 180 I never once Kangarooed it. Then I moved on to a floater KC and I had my first kangaroo landing. Then used crow before BVM announcment and started greasing them in.
I did notice at stock c/g location that if your not nose high 3' from touchdown that theres not enough elevator authority to get it high, almost as if it were in ground effect per full scale.

Another interesting point is I put an AMT 400 on in place of the AMT280 I've flown with for 3 years and it shifted the c/g by 5/16" rearward of OEM spec. With this newer location I definately felt more elevator authourity at flare and easier to get nose high in final.
The AMT400 residual thrust seems as its allot less than the AMT 280, sure is noticably easier to land. I've had enough elevator authority now to touchdown nose so high I can drag rudders. looks strange with such a long nose moment.

Using an Eagletree telemetry, I am now routinely 40-35MPH at touchdown with the AMT400 versus 50-45MPH with the AMT 280.

Hi - I have been flying my Nitro Planes Bobcat 52 for a while now, and the best setup to stop the bounce has been about 1/8-1/4 UP Spoilerons. This lets the jet sink nicely on final, and I can keep the nose-wheel off the ground for the entire length of the paved runway.