I need a little help with my taildragger. This is my first taildragger. It is a WM Rambler 45 and I have the CG setup about a 1/4 of an inch in front of the recommended CG point (this is without fuel). With Fuel, I assume that the CG moves even farther toward the nose. I am still breaking in the motor and have been trying to taxi on the grass at my local field but it noses over very easily (as in all the time).

What are the things that I can check on? I know that you should use full up elevator when taxing around but it still has a tendency to tip.

Thanks,

Jeff

Your wheels may be too small for the grass and/or the grass may be to tall and thick.

Danny beat me to it. The wheels that come with many ARFs are too small for grass.

I was wondering about that. I actually swapped out the wheels. The wheels that came with it were foam. I swapped in some real rubber wheels however, I made sure to keep them the same size. I believe that they were 2 1/4" wheels. The Rambler has retracts which, in the long term limits me in terms of how large I can go, however, I plan on using the plane as a fixed gear, low-wing trainer in the near term.

What size wheels are typically used on grass? It is quite bumpy. I will be going to the local club meeting for the first time in a few weeks and I will be sure to inquire about this.

Thanks,

Jeff

Ditto on wheels. Min wheel size for most grass fields is about 2.25"-2.5", IMHO. (I've seen grass fields that were like golf greens, or maybe fareways. That's different, small wheels work there. But most fields aren't that low cut). If your field is like my jungle/field gets in the spring, 2.75" or 3" is more like it.

Having the CG foward makes it worse as well, for obvious reaons. If it's wire gear, try bending it foward a little bit if you can. (if it's retracts, then that won't work, obviously).

Also make sure your wheels roll freely, and are aligned correctly. The more easily the wheels roll, the better.

Thanks for the size recommendation. The only potential problem I see is that when I switched from the foam to the rubber wheels, the width of the wheel increased slightly. It was enough that my wheel collar is basically at the very end of the wire shaft. Is this a common problem? Are there any workarounds to "extend" the shaft area or to fix the wheel to the gear?

Tough one. It's not a problem if the axle goes all the way through teh collar, but doesn't extend past it more than a hair. If you have a collar inside of the wheel, you might be able to remove that one and just use a washer or a spacer or nothing at all, depending on the gear. If you shop around, you might be able to find wheel thickness measurements, I know different brand wheels vary in thickness (since I've had the same kind of thing happen when changing wheels), but I haven't a clue as to what brands are narrower in various sizes.

Is it wire gear with a single strut that bends in to the axle? If you want to get extreme, you can cut off the bend, and put on bolt-on axles that are often used with retracts. That can give you a longer axle to work with (too much trouble in my book, but possible). If it's flat metal gear, you can use a longer bolt instead of an axle.

I ran into the same problem with the WM Super Sports 40. The standard wheel size that works well at our field is 3". The axles are too short to mount 3" wheels on them. I had to cut off the axle off and add an Easy Adjust axle to the wire section that comes down from the wing. Now you can't use the retracts without mods. Thats why retracts on a grass field aren't such a great idea either!! Don't lnow if you know it, but its standard practice to use full up elevator when taxiing to keep the tail down. [8D]

Fastsky said what I was about to ask... you are holding full up elevator when taxiing around, right?

Ummm, RichD and Fastsky, you might want to review his first post, he did say he knew to hold full up elevator

One thing I wasn't clear on in the originoal post was weither the flipping was occuring when taxing, or when on take off roll? If you're flipping when taxing, and already holding up elevator, then you are doing it right, you just need to do more of it, more up elevator, less rolling friction (bigger wheels, axle alignment, etc).

If it's on take-off, it may have to do with elevator timing.

I don't know how many out here are familiar with the Rambler 45, but, it has retracts. A lot of planes with retracts have this same problem, as do some scale models. The problem stems from the main gear being too close to the CG and running the plane a little nose heavy, will cause it to nose over, simply because of the fulcurm point. Try to move your balance back to the CENTER of the recommended range and see if that helps, I think you'll be very surprised.

Ken