My Bobcat composite gains a lot of altitude when I drop the gear and then again when I drop the flaps. Can someone explain how to mix some offsetting elevator so when I put the gear down it won't gain so much altitude? Second, how much mix should be used to offset the flaps coming down? In the crow instructions it says to mix in some up elevator??? But seems to me I should add a down elevator mix. I'm using a 10X.

Gone to code "66" (flap system) and there you can mix in the correct amount of elevator trim needed. You may have to do a couple of flights to get it correct. If it is gaining altitude when you drop the gear it is usually a indication that you have too much speed when dropping the gear.

I'm assuming you are using the three position switch for flaps. On code 66 put the switch in the mid position (take off) and put in a couple of clicks of down elevator, then put the switch in the land position and put in a couple more clicks then try it out.

Are you using crow??

Trying to remember on my composite bobcat, but I want to say it was not a lot of down required...maybe 1/8".

Bob-O is right that the Bcat Composite will climb when dropping the gear with excess speed. As for the elevator, you definitely need up elevator mix as per the BVM manual when flaps go down. I'd suggest that you use the numbers in the manual and adjust as needed. If it is flying too slowly in the landing pattern with flaps down, take out a point or two of up elevator mix. If it is flying too fast in the landing pattern with flaps down, add in a point or two of up elevator mix. If the plane initially balloons excessively on flap deployment and then settles down, you may be deploying flaps with excess air speed. This is my experience with the Bcat, FWIW.

I thought Bob said down elevator? So does the plane pitch up or down with flaps?

And I can't find anything in the manual about this (or on the plans) all I see is that it says if you mix in 3/4 inch or aileron "crow" you will have no pitch change with flaps down.

Is anyone seeing this, with crow you need NO elevator mixing at all?

Thanks in advance,

Sorry can't attach a PDF file.

Matt, go to BV's site, under jet kits, go to BobCat and there is the PDF file for setting up crow. Under disabling flap lever there are instructions on setting elevator trim.

After reading the post again, you want to add down elevator where the instructions say to mix in up elevator. Have you tried slowing down the BobCat a little more before you deploy the flaps?

Another trick I use is to use the servo speed slow down for flap deployment, with a really slow moving flap deployment the balloon effect is less noticable even at higher speeds than desirable.

Hi Bob,

This is what is in the JR setup:

That is NOT in the Futaba setup. Thanks for the tip. As you said, it says up elevator, and you are saying down, right?

In both cases (JR and Futaba) they say:

I took that to mean that crow eliminated the need to use elevator trim at all. I guess I will just dial it all in.

Regards,

I will slow down more and I'm sure that will help. But the point about adding UP when you drop flaps with or without crow is what does not make sence. If flaps make the plane climb why would you want to add more up elevator in the mix? Sounds to me like it should be DOWN. Thanks for all the input!!

After the initial balloon at pattern speed the model will pitch its nose down if you do not add the up elevator to the mix.
I had a P-70 in my Bobcat and found that 3/8"-1/2" up aileron was plenty to slow the model.
I was able to operate off a 450 foot asphalt runway with ease with the Bobcat.
Bob

R_Belluomini is correct. Once the Bcat settles down after flap and gear deployment, you need up elevator mix. As I recall, mine is also in the 3/8" to 1/2" range. Same for two other Bcats that I checked when I was setting mine up originally.

This is how I crashed a Bobcat. I thought I remembered the Bobcat ballooning after flaps came down like most of my other aircraft, so I programmed down elevator, but after I hit flaps the Bobcat started flying down really fast. I tried to program out the mix, but ran out of fuel before I could finish and she went swimming in the pond!!! In hindsight I should have just landed without the flaps.
Oh well.
Scott

Could anybody possibly tell me how much flap you need on crow since i misplaced my template to check it?
Thanks!

Jordan

This is confusing because with most full size aircraft, you have to push forward on the stick initially when you drop the flaps to over come ballooning. From there on you use throttle to control the glide, and finally the elevator to control the flair at landing.