Center of Gravity & " Tongue Weight "

[tomhall]

I have recently been signed-off to solo. I have an RAF 2000 with Don Parham's extended keel ( 18 " ) and his HS. This has caused a " light nose wheel ". I have good advise from some of you already ( lighten the springs on the Pitman arm & maybe adjust the mast forward ), but has anyone considered puting a scale under the nose wheel to determine the " down force " or actual weight on the nose wheel. There are certainly variable factors involved; pilot/passenger weight etc. But again, there might be an ideal range of " tougue weight " for any gyro using it's weights and geometry. Some have moved the axle back an inch or more; I hesitate to do that yet. I weigh 250 lbs. and currently my passenger is Sandy ( 100 lbs. of sand bags ). Tom T. Hall in MN

[Doug Riley]

1-place Bensen clones of around 500 lb. gross weight seem to have about a 50 lb. load on the nosewheel when the pilot is aboard. This gives you rotation at a time when the blades are coning a bit and you're sure not to flap them into the tail, prop or ground. (For comparison, the Gyrobee has a low tailwheel and almost no ability to rotate; takeoff in a 'Bee can a bit clunky as a result.)

Light tandems (GW under 1000 lb.) can get up into the 200 lb. range for nosewheel load.

I would guess that side-by-sides ought to use the same 10%-of-gross rule as the 1-place Bensen, for good rotation behavior.

[GyroRon]

We tweaked Barry gyrobee - and I think Rick Martin did his as well - to get a little "rock back" onto the tailwheel during takeoff. It takes off just like any other gyro....

[gyroplanes]

First off, congratulations Mr. Hall. I knew you would do it.

Second, your tongue weight shouldn't matter if you keep it in your mouth. It would just be another mass within your body mass as with any internal organ.

I don't remember, is your tongue extraordinarily long? Do you use it to change radio frequencies in flight? If so, perhaps you and sandy will notice a slight, forward C of G shift.

If I remember correctly, Ron Awad said he had a similar C of G change problem with another unruly appendage. Perhaps he can help?

[Aussie_Paul]

...I have good advise from some of you already ( lighten the springs on the Pitman arm & maybe adjust the mast forward ),

Tom, from my experience of operateing RAFs since 1997, I would not call that good advice. Only change the mast position if the keel does not fly level with two people at cruising speed. The springs, only change those if you are running out of trim travel.

You will find that if you move the axle back 2" she will be nice, but why not go the extra and do what Larrye B has done. Also move the axle back 5". You then have the best Raf that be modified at the least amount of expense!!!! Sooooo much more user friendly!!! ;)

Tom, congratulations on your solo sign off.:D

Aussie Paul. :)

[tomhall]

Paul, If I do move the axle back, I want to do it once. Hard to know how many inches...............figuring my weight ( 250 lbs. ) passenger wt. and any other variable. Also, the spring tension I mentioned were the springs on the Pitman between the nose wheel and the rudder pedals. Tom T. Hall