Checking the Head Assembly for excessive play

I've been giving a lot of thought to how much play in the head is too much and what possible affect play has on flight performance. In reflecting back to my Huey mech days I realized what is missing is a set of standards. In this case I think what is needed is a method to measure play in the head that is repeatable by all of us BLADE owners. Then we can compare the data and look for trends, etc.

So, after careful consideration I came up with two tests that can be performed by all BLADE owners.

Test 1
Checking for cumulative play in the head along the mast's axis.

Test 2
Checking for play between the Flybar and Main Blades along the axis of rotation.

Test 1 will show the total play added up from the play in various components. Those components are:

• Servos (021)
• Servo Pushrod Control Links (045)
• Swashplate (017, 018, 043, 044)
• Paddle Control Pushrods (009)
• Paddle Control Frame (031)
• Rotor Head (005)
• Pitch Control Links (006, 007)
• Blade Grips (037)

Test 2 will show specifically the play between the Center Hub and Rotor Head. More precisely the mating keyways shared by these two components.

What I hope to accomplish with these tests is to see what effect these 2 types of play have on the flight characteristics of the BLADE. I believe we will learn a lot from these tests so please help out by performing the tests on your BLADE and posting the results in the user forum.

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Performing Test 1

We will use the aircraft's weight to cause the deflection which will induce the play. This helps create a standard that can be repeated by all. That is also why the weight of your BLADE is useful data for this test. If your BLADE is unusually heavy or light please disqualify yourself and do not submit test criteria as it may skew results.

Remove the Center Hub Cap (030) by first removing the retaining screw (029). Figure 1. Remove the Canopy (054). Install the stock 9.6v 650mah NiMH battery but do not connect it. We are using it for its weight only. Center the swashplate. The swashplate must stay in the same position for both measurements in Test 1.

Have an assistant hold the aircraft off of the ground by the Flybar as shown in Figure 2. Have your assistant hold the flybar on a slight angle to allow your ruler to contact only the top of the Rotor Head Sleeve (034). Now, using an accurate measuring device, measure the distance from the top of the Rotor Head (034) to the top of the Center Hub (008) as shown in Figure 3. Record this measurement.

Remove the stock 9.6v 650mah NiMH battery and hang it from the Flybar precisely at the Flybar Weight (069) as shown in Figure 4. Place the aircraft on the bench. Have your assistant hold the flybar on a slight angle to allow your ruler to contact only the top of the Rotor Head Sleeve (034). Make sure that the battery is hanging freely and against the Flybar weight Collar(069). Again, take the same measurement. Record the results.

Subtract the small number from the big number to determine total play.

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Performing Test 2

Rotate one of the Main Blades (042) within its Blade Grip (037) in the normal direction of rotation until the blade aligns with the Paddle (001) as shown in Figure 5. The idea is to have the corner formed by the Paddle trailing edge and outer tip remain over the blade throughout the play travel. When the blade is positioned correctly tighten the Main Blade retaining screw (036) to prevent the blade from turning within the grip.

Rotate the Flybar until it is perpendicular to the airframe and stand the aircraft on its nose as shown in Figure 6. Have your assistant hold the aircraft as shown to keep the main rotor blades in position during measuring. Hang the stock 9.6v 650mah NiMH battery from the Flybar precisely at the Collar (004) as shown in Figure 7. It is important that everyone use the stock battery and position it precisely to maintain the standard.

Measure from the Main Blade trailing edge to the Paddle trailing edge (Figure 8) and record the result. Don't move the Main Rotor Blade (042) while measuring. Now move the battery to the other side of the Flybar and measure again (Figure 9). Record the result.

Subtract the small number from the big number and record the result. This is the total play.

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Now these numbers alone mean nothing. They become useful when many people have performed the same test exactly in accordance with this standard. We need these tests performed on a few machines that have never been flown to determine what the "out of the box" play is.

Once you have performed the tests, gather the following data and post it in the user forum under the topic "BLADE head play data":

• The total weight of your aircraft when tested (if you are able to weigh it)
• How many flight hours are on the head assembly (not the aircraft)
• Describe aircraft's stability in a hover (steady, yoyos, abrupt pitch changes, etc.)
• Describe the flight characteristics in FF (if applicable)
• Aircraft setup (stock, 370 w 8T-1320mah 3S lipo-GWS DD tail)
• How many crashes have these components experienced
• Test 1 amount of play and unit of measure (.234 inches, 6mm, etc.)
• Test 2 amount of play and unit of measure (.234 inches, 6mm, etc.)

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Look at the topic in the user forum now to see how the data should be reported.

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I think this is a worthwhile venture that will yield results. We may learn that play has nothing to do with flight characteristics (but I doubt it). Or we may find that problems start to arise when play exceeds 'x' amount.

This is truly a GIGO (garbage in - garbage out) proposition. If you provide bad data the outcome of the tests will be flawed so please measure accurately and perform the tests exactly as outlined. Most importantly - the more people performing the test, the more reliable the data will be, so please contribute. If you are unsure as to how the test is performed email me by using the Contact Us page or ask in the User Forum.