I have a Kangaroo that if I land hot, wants to bounce like a
well, kangaroo....
I have a fair amount of positive incidence sitting on the gound to aid in rotation on take off, I'm thinking of reducing it, but how much is the question.
How much incidence do you other Kagaroo owners use on yours?
Will this help the problem?

If I slow it way down, no problem.
But sometimes on windy days, it's hard to judge ground/air speed.

Appreciate any comments.

Thanks
Pete Stapleton

Hey Pete,

Same problem here! I don't believe incidence will completely resolve the problem. I have lowered my nose gear a bit and still have the kangaroo effect. I have been hearing some reports of guys installing canards which seem to help with this tendency but have not been able to confirm this yet. Anyone have suggestions???

Pete & Todd:

Screwing with the incidence won't do it. To really damp and even stop the hop 2 things:

1. Get the C.G. right on dry, and then try not to land with too much fuel. The Roo lands much nicer with the C.G. as far aft as you can get it for landing. Allows it slow down better and not bang down on the nose gear oleo spring.

2. Learned a little trick from Don Hoffman who flys a Roo with a RAM 750 on it. Lots of flights. He's a member of the Sarasota Club.
What he does is put on some brake for landing, like just before it starts to really grab. He uses a Smooth Stop with BVM W/B.
It also works with UP-6 with Glennis W/B or BVM W/B, but not with Smooth Stop and Glennis since even at 1/4 ON with a Smooth Stop(high pressure system), there is enough pressure to totally lock up Glennis Brakes which are a low pressure system. 40 PSI will lock them up.

The results are amazing. The Roos and HotSpots stick like glue--and the nice thing is that you probably use up a little more rubber over time, but it does not produce flat spots if they are set right. He uses one of the rotaries on the side to set the brakes. Don rarely uses up more than 1/3 of the 700 ft. Sarasota runway, usually allot less. If you have it set right, absolutely no skidding either.

My buddy and I fly our HotSpots and F-15 off grass fields, and one of our fields is only 250ft long. Using the preset, I can regularly get it stopped in 100 feet or less from touchdown point.

This really isn't new. BV and allot of other top flyers use a little landing brake as well on the big scale jets. I think BV has it posted somewhere on his website.


Tom

Thanks Tom! Great tip...

I already cut out doors behind my gear to move my batterys further back, I assumed getting the CG further back would help a bit ( I was about a half inch forward on my cg). I will have to try the brake idea! Are you using a switch with a preset amount of brakes applied or a slider that only applies enough brake for landings? Already using BVM wheels and a smooth stop, should be a cinch to set up.

Thanks again....
Todd

Well i don't know if this does anyting and i just started flying my Roo, but the person who built my plane modified the nose gear further forward than other Roo's. I only have four flights on it but all landings so far have stuck like glue. I have slowed it down though, and haven't had a hot one yet, so i don't know how it would do with a higher landing speed. My nose strut is 10 inches back from the nose of the plane. I like the brake idea. i will use it for extra insurance from hoping..

Andy

Hey andy,

Sorry to get off the subject, but I was wondering if there are many guys flying turbines up your way, and if so, where are they flying? Thinking of making a trip up that way and wondered who might be flying turbines.

Thanks!

Tom, my cg is right on the money.
I landed one time hot and was about to run off the end of the runway into the grass, so I hit the brakes(mine are proportional) and the thing hopped up and down like crazy. My brakes are applied with down elevator, so everytime it hopped up the down slammed it into the ground. Really beat up the gear. I am using Spring Air with 3/16 wire struts.
I'm not sure how hard I applied the brakes, and it was over in a few seconds.
Wasn't till later I realized what was happening.
It had always jumped up in the air before, higher and higher till it flops over on it's back. Happened twice now, always on a too fast landing. Usually I can hold it off until it almost stalls and then its no problem.
Was hoping for a nice simple fix. Maybe if I apply the brakes lightly when it first touches down.

Thanks
Pete Stapleton
Simjet Rep

Pete:

My buddy and I really like the brake over on the snap roll button.
This was described in one of the Horizon Hobbies catalogs.

As soon as landing is assured in the flare with engine at idle, I reach up with my index finger to the snap roll button on the 10X or 10SXII, and hold it down. Then you can play the flair just like you ordinarily would, and not worry about coming off the elevator when you touch down. I fly with a tray, but it also works for my buddy who is a thumb and finger tip flyer with just a neck strap.

Tom

Hey Tony.

I think im the only turbine flyer so far. A freind of mine has a BVM MIG under construction but has not flown yet. I have been flying at the dry lake beds. Jean dry lake, and the Eldorado dry lake. I do not have my waver yet, but when i get it, i plan to fly it at the North flying feild. I only have 4 flights so far on the Roo, so ill log some more and hope to get down to one of the Rabbit get togethers and get my sign off. If you get to Vegas, drop me a line...I'll fly with ya.

Andy

Pete S,

hey bro', first and foremost don't give up on the old roo. the key to reducing the hippity hop is to have the wheels touch mother earth only after the aircraft has decelerated to min flying speed. if your coming in hot, the positive incidence is only going to keep you flying and then you're off to the races with PIO. ( operator induced oscillations )

I had one of the first Roos off the assembly line, got it from a buddy who won it at Superman '97. I bounced my share of landings until a good friend heckled me into really slow flying the beast. I mean no kidding park that nose up, 45 degrees and control the forward speed with throttle. never had a problem with the old hippity hop again. I admit, it is somewhat uncomfortable looking at the bottom of the plane as it crosses the approach end of the runway but you gotta have faith.

I didn't use a gyro or speed brake. call me crazy but I don't think it needs it unless you are flying off a really short strip. It had a 2 liter soda bottle and a 16 oz hopper tank. used BV sport wheels and brakes on Robart 650 struts attached to an old set of spring air retract units. wobbliest little bugger you ever saw but it was fuss free. I balanced it at the 100 mm mark and aligned the trailing edge of the wing with the trailing edge of the fuselage and then set a very slight postive incidence to the nose gear. I'm sure the kits coming off the assembly line have better installation instructions.

anyway, this set up worked for me, just like so many other valuable techniques and tips that have been provided by so many other guys on this forum.

kiss, a principle I live with on a regular basis. life's too short othewise.

have fun and good luck,

buck

Thanks for all the good replies.
I have 76 flights on the Roo since mid Aug and I love flying the thing.
Only had three bouncers, but was looking for a way to avoid it in the furure.
Only happens on windy days when I come in too fast.
My friends Roo almost never does this, his cg is farther forward than mine. He also has a different landing gear setup.
I will try the brake thing, maybe mix my brakes to another channel so I can set a little brake-on for landing.

Thanks again

Pete Stapleton
Simjet Rep

PS how many of you guys are going to FJ?
I plan to be there Fri through Sunday.