I have been thinking of ways to reduce the flap extension forces in my aircraft to reduce pilot workload, literally, which led me to compare to the Maule.

I find pulling on full flaps in the Maule to be quite easy, by comparison.

I wonder why the Maule flap-handle has such low forces, is this just clever geometry, aerodynamics, or perhaps spring loading somewhere in the system? Or some other solution I've not even considered??

Thanks guys.

Battson wrote:I have been thinking of ways to reduce the flap extension forces in my aircraft to reduce pilot workload, literally, which led me to compare to the Maule.

I find pulling on full flaps in the Maule to be quite easy, by comparison.

I wonder why the Maule flap-handle has such low forces, is this just clever geometry, aerodynamics, or perhaps spring loading somewhere in the system? Or some other solution I've not even considered??

Try lowering them when you're going faster.

Ok, seriously, compared to other floor mounted flaps, I don't find the maule that much different. What are you flying that has tougher flaps?

I never noticed much difference in mine either... they are a bit harder to go full flaps than my old tripacer but then they are bigger...

The effect of minor amounts of dirt, burrs on metal parts, corrosion, etc. can be greatly amplified when there are air loads on the parts.

Same principle as when you can easily drag a piece of plywood across rough ground by itself, but it gets exponentially more difficult when you put weight on the wood.

the majority of these flap systems never get maintenance, or they get a squirt of WD-40 every three years and never really get disassembled and cleaned.

Where I am coming from isn't about maintenance. I only compare to Maule because I know how their flaps feel. Equally Cessna, etc.

By design the Bearhawk has a lot of flap. But the force required at the handle to actuate that flap - compared to a Cessna or Maule - it's a disproportionately large handle force - an unmanageable force in a turn, or over Vf speed.

There is some design difference which causes this. No other explanation necessary.

I just want to know what that difference is.

To me, it feels like the Maule ones could be spring loaded to lighten the force required at the handle??

Battson wrote:To me, it feels like the Maule ones could be spring loaded to lighten the force required at the handle??

The maule is spring loaded, but I'd have to ping Jeremy to know anything beyond that.

Goes back to physics 101. What appears to be a small difference in pulleys, angles, etc in the system can make a pretty big difference in perceived force at the handle. Also, differences in flap surface area and even slight differences in flap deflection angle, flap airfoil design, and probably a dozen other factors can make a big difference in force required.

But, why would you even consider flap application above Vfe, as suggested in your post?

Sign up at a local gym, I reckon....you only need right arm workouts, right?

MTV

I think it has something to do with that good old American farm boy ingenuity that is just commonly found in Maules, also the intelligent & good lookin people who fly em has a lot to do with it!

mtv wrote:Goes back to physics 101. What appears to be a small difference in pulleys, angles, etc in the system can make a pretty big difference in perceived force at the handle. Also, differences in flap surface area and even slight differences in flap deflection angle, flap airfoil design, and probably a dozen other factors can make a big difference in force required.

But, why would you even consider flap application above Vfe, as suggested in your post?

Sign up at a local gym, I reckon....you only need right arm workouts, right?

MTV

I didn't mean Vfe, it's "Vf4" (4th notch) that is the issue, and really just as an indication of how high the force actually is right at Vf4. Barely manageable...

I'm all done up to physics 400 level, and mechanics, so no worries there.

mtv wrote:Goes back to physics 101. What appears to be a small difference in pulleys, angles, etc in the system can make a pretty big difference in perceived force at the handle. Also, differences in flap surface area and even slight differences in flap deflection angle, flap airfoil design, and probably a dozen other factors can make a big difference in force required.

But, why would you even consider flap application above Vfe, as suggested in your post?

Sign up at a local gym, I reckon....you only need right arm workouts, right?

MTV

At a perfectly reasonable speed for full flaps in the BH, the force required to pull the lever into the last notch is considerably higher than a Maule. On a warm day with my usual clammy hands, I struggled to find that last notch and my manhood became suspect in Blackrock's eyes. This is the mystery we're trying to unravel. Not knowing the innards of the Maule design, I think Battson is trying to gain some insight as to how the BH could be improved.

The original M4 and M5 flap activation was 15 and 35 degrees.
This was updated about 1979 to 20 and 40 degrees. All this was accomplished with a simple direct cable passing over numerous pulleys then cycling bell cranks to cause pushrods to force the flaps down.
Time and wear and breakages proved that those degrees downward, were enough for the system.
More degrees required reinforcement of the flap handle.
Moving on to M6, MX7, MXT, M7, MT7, M8 and M9, the flaps now go from -7, 0, 24, 40, and as low as 48 degrees.
On this system there is a bungee spring cartridge in the pull cable that stretches if flaps are extended at speeds higher than intended.
In fact, the 48 degrees will not be down fully until you reach 55mph. (BD Maule ingenuity)
No longer is a cable used the total route. The initial cable converts to a chain over a sprocket which is attached to a torque tube passing from wing to wing . At ends of torque tube are short cranks which push the pushrods which activate the flaps which are quite long.
Though the POH says do not activate flaps above 90mph, common sense tells some of us that is ok for 24 deg but how about 80 or 75mph for 40deg and 65mph for 48deg, if one wants to be kind to one's aircraft.
Though the BH appears to have borrowed a tremendous amount of Maule ideas, maybe they missed this one.
BD's -7 deg idea can increase cruise by up to 6mph, but it is especially useful in short landings where the flaps are raised from 48deg down to -7deg up at or a second before touchdown. This has the effect of downward lift at back of the wing placing max load behind the main gear and allowing max braking with better traction and less nose over tendency. In fact on grass or gravel one can land with brakes on.

maules.com wrote:Though the BH appears to have borrowed a tremendous amount of Maule ideas.

Aside from the double cargo door, and the all-metal wing, what else has been borrowed? This is the only steel tubing fuselage I have had the experience to intimately inspect, so I am genuinely asking what is uniquely an homage to Maule?

Probably already tried this, but, have you tried climbing to altitude and slowing it down as much as you could before applying full flaps to see if it behaves any different?

I have zero BH experience, so take it with a grain of salt, but without fail , every Skywagon owner I have encountered that complained about excessive flap extension forces was applying flaps at higher speeds (assuming a clean and free system). Flap extension speeds, are maximum speeds, and in the case of those Skywagon owners, they tended to fly them like they were minimums.

Most things I fly I tend to use the flaps as a 'trim' of sorts. Using them this way tends to be easier on the system, and easier on my arm.

Take care, Rob

A inline spring cartridge could be a nice solution. The BH is the only plane I've flown with flaps so I have nothing to compare it too but they for sure take a lot of force to deploy. Like Z said, the last notch of flaps makes you question your manhood. I rarely used the last notch because the BH I was flying didn't have the updated flap handle so it would flex when pulled on and the cam wouldn't catch unless you were already really slow. I wasn't comfortable slowing down that much then straining to engage that last notch.

That spring cartridge would allow you to engage the last notch and the flaps would fully deploy by the time you slow down enough to use them.

whee wrote:A inline spring cartridge could be a nice solution. The BH is the only plane I've flown with flaps so I have nothing to compare it too but they for sure take a lot of force to deploy. Like Z said, the last notch of flaps makes you question your manhood. I rarely used the last notch because the BH I was flying didn't have the updated flap handle so it would flex when pulled on and the cam wouldn't catch unless you were already really slow. I wasn't comfortable slowing down that much then straining to engage that last notch.

That spring cartridge would allow you to engage the last notch and the flaps would fully deploy by the time you slow down enough to use them.

Spring cartridge? How would that work? Please elaborate. I'm building a Bearhawk and have noodled this a bit. Have done a few drawings using vacuum assist. Wanted to get a look at a Grumman Widgeon in Dillingham during a100 hour inspection.....but the aircraft and pilot were lost.
Mark M.

Zzz, when a Pacer owner wants to effect a 'rise' from a Maule owner, he/she says BD copied the Piper.
Same thing usually happens when Maule owner suggests BH copied the Maule. I know, this is not your case here. You're building.
Basically there are few ways to carry 4/5 people in the sky.
Sheet metal or truss tube.
Maule's #1 big difference and recognition point has always been the door system, low cost parts and maintenance, ruggedness and broad ratio of speeds. 40mph to 169mph (not counting the turbine)
The truss steel tube fuselage and full metal wing kept weight, strength(crashworthiness), and cost under control.
I have not measured the structural pieces to build a BH but note that the general character of wings, doors, fuselage, landing gear, engine choices and performance are similar.
I have flown a BH very little and Maules alot and so only have my personal sensations to guide me.
The two items I would want to consider if building would be control input and resulting effect which is the question in this discussion.
Flap forces and Rudder effect/pedal travel were my primary concerns.
Seating or headroom were my secondary one. I just felt vertically confined in the pilots seat.
If a BH was ever construed as a partial Maule clone, I think BD should be proud.

To the other Flap comments, the cartridge is not necessarily to make lever pulling forces less, as it is to correct excess mechanical forces caused by the pilots mistake of overspeeding flap extension speeds.
As usual, it is up to the pilot to select appropriate speeds for each flap setting.

I suspect it's mostly a geometry issue. Pulling the last notch on the BH, the handled is vertical and right beside your thigh. It's hard to apply a lot of force in that position. The Johnson bar in the BH is also shorter, and the handle is a narrow diameter - making it hard to get a grip.

I suspect a longer handle will help - but I wonder how Maule/Cessna get's the same range of flap movement, with a shorter handle pull length, without increasing the pull force required?? I figured there must be some clever geometry going on.

When I was flying BH #357 the flaps definitely told you when the speed was correct for full engagement. I have decent arms but 5mph too fast and even ARNOLD could not pull the flaps to 50*. It definitely is a geometry thing and in talking to Bob Barrows years ago it was purposely designed that way to prevent damage to the flaps and wing from premature engagement.
KenW

Go fly a later model Husky, and try pulling on full flaps right at Vfe.....it's a bit of a wrestling match.

Aviat eventually rotated the handle downward, so that it's very close to the floor so that at full deflection, the handle isn't pure vertical and slightly behind your hip, as was the case in the mid year airplanes.

BUT, the best thing you can do in the case of applying full flap is slow to slightly below flap speed, reduce power to idle, gradually pitch nose up to maintain altitude while decelerating, pull on full flaps, then apply an appropriate power setting to resume doing what you were aiming to do. Slow it down, which reduces air loads, which reduces flap handle forces. This does not have to be a real dramatic process, nor are you getting anywhere near a stall, and the deceleration is only momentary.

Cessna dealt with the issue partially by installing one hell of a long, robust flap handle. There isn't room for one that size in most of these airplanes.

I've never flown a Bush Hawk, but I'd bet good money that using the technique I just described will make flap actuation pretty easy. Does in the Husky.

MTV

mtv wrote:BUT, the best thing you can do in the case of applying full flap is slow to slightly below flap speed, reduce power to idle, gradually pitch nose up to maintain altitude while decelerating, pull on full flaps, then apply an appropriate power setting to resume doing what you were aiming to do. Slow it down, which reduces air loads, which reduces flap handle forces. This does not have to be a real dramatic process, nor are you getting anywhere near a stall, and the deceleration is only momentary.

I have been doing as you describe for the last couple of hundred hours - getting slow first. I always use full flap when conditions allow, it just lands better.

Now that I am landing some tighter spaces - I don't always have enough room to do everything my way. I want to be able to apply the last notch of flaps at the desired time, without undue effort. There are also other factors which I wont bore you with.

I think I will try a larger, longer handle tomorrow, and see what difference in effort it makes. There is room to extend the handle at least 6" (50% longer), so if it works, I will design a permanent addition.

I have spoken with the designer about the flap design. It sounds like it's just incidental. The design was changed many years ago, to make it stronger - much like the Maule. He is prepared to approve a supplemental design feature.