This Months Flying Tips
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Adjustable "V" Tail
The advantage of an adjustable "V" now coincided with the logic of "V" tails are easy to make. Many planes never flew the same after the "V" tail was added. Most of my summer flying in 1991 was spent flying several "V" tail Tempests. I was trying to decide whether or not to change the Tempest kit to include "V" tail blades and instructions.
There has been some bad press about "V" tail that
I can personally say is false. "V" tail R/C sailplanes can barrel roll with rudder and elevator. They can also do outside loops and fly upside down with the best of them.
While deflecting the wing control surfaces to the Crow position the "V" tail control response is excellent. With the TMSS I am also flying a Bounty Hunter fuselage "V" tail with 100" wings, weight 4.5 lbs. In contrast to the Bounty Hunter, I also fly a "V" tail Candide with a 110" wing with average cord of 5". It has the J.C.-22 airfoil on it. This is similar to the HQ 1.5/7.5. The performance of both of these sailplanes is fantastic.

Rudder And "V" Tails
After flying with and without rudder mixed with the elevator on the Tempest, Candide, and the Bounty Hunter, I have found it is better to have them mixed. I have experienced the rudder to work best if it has three times the travel of the elevator. With the use of dual rates I have had good results at high speed with half elevator and twice the rudder through as elevator for the rudder half rate setting. I use the full rate setting during landings and take-offs. The yaw control authority is very good clear up to stall speed.
To finish the point I made in the beginning. "V" tails are easy to make and fly well.
Their performance depends entirely on their angle of attack in relationship to the wing's angle of attack. You need to be able to change this easily. The two-screw mount shown above is an illustration of the mount I use to hold the "V" tail in place. Oblong the forward hole in the "V" tail platform to change the yaw trim.


Assuming you just finished your new slope soaring model, followed the suggestions for building it straight, and are now ready for your first flight, what's next?
Go to the slope, be sure no one else is on your channel, do a radio check, be sure there is sufficient lift, take a deep breath, and launch your model!
It should fly straight and level, with very little trim corrections. Now you want to fine-tune it to fly hands off.

If you made any trim corrections with your radio be sure to readjust the control linkages so that the controls are centered after your first flight.
Did your plane appear sensitive when responding to control inputs? If so, reposition the control linkages further out on the control horns to reduce throws. If this isn't sufficient,position the linkage further in at the servo horn.
If after reducing throws the model is still sensitive to input, it may be tail heavy. Gradually increase nose weight until you are comfortable with the flight characteristics.
If possible try to shift components towards the nose of the model,rather than adding weight.
Another indicator that the model may be tail heavy is if the nose tends to pitch up as speed increases.
If the model is slow to respond to control inputs, you may need to reposition the control linkages further in on the control horns to increase throws. If this isn't sufficient,position the linkage further out at the servo horn.
If after increasing throws the model is still slow to respond to input,
it may be nose heavy. Gradually decrease nose weight until you are comfortable with the flight characteristics.
If possible try to shift components towards the tail of the model,rather than adding weight.
Another indicator that the model may be nose heavy is if the nose tends to pitch down as speed increases.
This gets a little tricky, but if you are reasonable sure that your model has the proper c/g and it still flys nose-up and/or tends to climb as speed increases, try reducing the wing incidence. Very slightly lowering the leading edge of the wing or raise the leading edge of the horizontal stabilizer. Increase the wing incidence for a nose down attitude and/or veering down as speed increases.
If the model flys o.k. in light wind, but has trouble penetrate stronger winds, gradually add weight at the c/g (center of gravity) until it penetrates the winds well.
Don't make the same mistake I did and build your model heavy. Sure enough, there will be days when the lift just isn't there for the heavier models.
It's always easier to add weight on a light model than to remove it on heavily built one.
If your model flys in a nose-up attitude when balanced at the correct c/g and the elevators are centered,lower both ailerons a bit.
If it flys nose-down, raise both ailerons a little. For best results seal all control surface gaps.

Enter a slight dive and pull straight back on the elevator stick. If your model does a nice loop, congratulations,don't touch a thing.
If it loops to one side,try adding a little weight at the tip of the opposite wing. If it snaps out of the loop, decrease the control throws.
If it doesn't want to loop, increase the throws. Decreasing nose weight can also help your model loop better.
Does your model have split elevators, like on the Foaminator 60?
Adjust the elevators as follows.Raise the right half and lower the left half of the elevator slightly if your model strays to the left (with the ailerons centered) and the opposite if it goes to the right.
Out of adjustment split elevators are especially noticed while doing a loop.
If you are having trouble flying inverted with
V-tail models, increasing (flattening) the angle between the tails can help. Reducing nose weight and increasing elevator throws can also help inverted flight for all models. Remember, models with flat bottom wings just aren't meant to fly well inverted no matter what adjustments you may make.
For planes with motors and especially those with large propellers, thrust angle is important.
From level flight quickly chop the throttle.
If the model pitches nose-up, decrease down thrust. If it pitches nose-down, increase down thrust.
If it veers to the left, decrease right thrust;
to the right increase it.
Models with ailerons will respond better to inputs if they have differential.
That is to have more up than down deflection in order to decrease drag on the inside wing during a turn. This is easily accomplished with a computer radio, but can be set up mechanically as well by offsetting the control holes on a round servo horn. If you do a lot of your flying inverted,
you don't want to have differential because it will cause more drag.
If your model tends to have excessive wing tip stall in slow speed turns, you can increase stability by introducing wash out at the wing tips. Put the wing on a flat surface and then raise the trailing edge of the wing tip about 1/8 inch higher than the leading edge.
This is easily accomplished by heating the wing covering while gradually bending the wing tip.
A word of caution. Doing this will adversely affect inverted flight and may lower the top speed of high performance models.

Vacuum Bagging Wings With Dihedral

Since most sailplanes have dihedral in the center, this seems to create a problem to vacuum bag on the skins. Not really!

Most people build on a flat bench. So you will have to build one side at a time to form the complete wing or center section.
Add all the other components that your instructions tell you to do. Also pre-shape your skins to fit.
Tape the trailing edge of the skins together,so it acts like a hinge. Apply the epoxy to the backside of the skins and squeegee off as much as possible to keep it light. Put the foam wing in between the skins. Do the left and right sides at the same time. Use masking tape to help hold the skins in place. Tape the skins together on the bottom at the center. Also put some tape on the leading edge to keep the skins together at the leading edge.
Now slide the wing into the bag. Keep this on top of the foam beds. Of course only one side of the wing will be down. Now draw down the vacuum to the correct vacuum (8lbs for white foam, 15lbs for blue). With the side that is down on the bench,put the top foam shell over the wing and add weights. Then relieve the vacuum for a couple of seconds and then reapply. Repeat this for the other side of the wing. Once the vacuum has been applied for the last time, you can actually hang the bag from a nail in the rafters.

More tips on fly and Building Good Flying Aircraft, as soon as I can get them in.