rcguy!

My Feedback: (69)

"Because it looks like Gumby is the owner?" :-))

Seriously, not a bad idea if you don't poke your eye out.

Believe me when I say it was spooky flying my R54 with the mini whip the first time. ALL the usual precautions were done, range checks with/without turbine running, etc.

I've used mini whips in helis for years and at times got the machine quite far out and up without trouble. Now I know the range is big time different...but I did have experience with them before using one in my turbine powered plane.

When I fly the R54 to the limit of my "comfort zone" it is really far away! She ain't no small machine. I do have the pump mounted in the boat tail as Bruce suggests. I for one, am very comfortable with MY installation of the Revolution mini whip.

Dave Rigotti

TommyWatson

My Feedback: (1)

I agree.
I have my pump mounted on the "ECU Tray" area and theECU in the boattail. The suction line is short and the pressure line is longer as it should be.

Never had a problem.

Regards

TommyWatson

My Feedback: (1)

G'Day Dave, sitting her in my hotel looking out over Kowloon Harbour. Just about to go to China.
Regards

f6hlct

My Feedback: (4)

Veering away from using the wire struts has proved to be a bit of a challenge. but things are moving along well now. As you can see, I have had to change the way that the nose strut is mounted in order to accommodate the different retract unit, as well as extensive modification to the Robart strut due to the very short landing gear length. You may want to consider this if you chose to use functional struts instead of the recommended wire gear. It will work, but be prepared to do some modifications to the hardware.

rcguy!

My Feedback: (69)

I found the stock setup to be extremely durable. I have bounced it pretty good early on and never broke anything loose. I did bust a wire strut once with no airframe damage. Just grab the nose strut and bend it forward. Eyes pop out at the field when I did this! A very sturdy bird!

Dave "going into kerosene withdrawal" Rigotti

wd40

My Feedback: (81)

The new Reaction is almost ready

wd40

My Feedback: (81)

In flight

rcguy!

My Feedback: (69)

wd40,
Nice! Easy to see!


Dave

BruceTharpe

My Feedback: (1)

Great flight shot, Mike! How 'bout sharing some data like turbine, final weight, any mods, etc... Congrats, my friend!

afterburner

My Feedback: (18)

Just wondering if when you guys set up your linkages, there was some slop at the rudder? I'm having a problem with my servo not coming back to center(about 1/16" at the rudder) in addition to some slop when the servo is powered and centered. The tube is secured along the entire length of the fuse and installed just like it shows on the plan. It seems to me that just the distance between the servo and horn would give you some slop unless you were using a solid rod. I'm using the recommended hitec servo and there's a tiny bit of resistance in the cable when the rudder is centered and It's enough to cause the servo to not come back exactly on center. I've releived some of the resistance by opening up the hole at the top of the stabilizer but I'm thinking the rest of the resistance is just from the geometry of the cable/tube. With nothing connected to the servo, the servo arm will return exactly to center. I tried a servo from the aileron and it does the same thing but works fine on the aileron. Battery voltage is fine and I'm hooked up directly to the receiver and I swapped receivers also. I also moved the rudder to the elevator channel in case it was the pot in the transmitter. Thanks.

Marty

Topgun2mo

My Feedback: (45)

Perhaps you should check your amp draw with a Hanger 9 inline ammeter to see if there is a bind.

afterburner

My Feedback: (18)

Mike,
I hooked it up with an Astroflight Whattmeter. It reads down to 0.1 Amps(100ma). It stays at 0.0 Amps when the servo is at idle. Its not binding, it's more of a slight resistance and a tap of the stick get's it back to the actual center. Thanks.

Marty

Jeremy300

My Feedback: (6)

How old is the servo??? It is possible there is some dust buildup on the pot wiper causing the false idle position.

Jeremy

TommyWatson

My Feedback: (1)

Don't worry about it. The flight loads will center the rudder OK. Mine does it a little.

Regards

afterburner

My Feedback: (18)

Jeremy,
Servos are brand new.

Tommy,
I'm not as concerned on the centering as I am on experiencing flutter due to some slop in the linkage. I've seen flutter on the rudder of some jets where the servo is very close to the rudder with a solid rod connection.

Marty

bobparks2

My Feedback: (1)

For most types of flutter, there are two motions that couple. If you can prevent EITHER motion, no flutter.

On a rudder, it would be the motion of the rudder itself, (slop plus flexibilty in the linkage and rudder ), and the other would typically be a side to side motion at the tip of the tail, from twisting the tail boom, from the rudder to fuselage mount not being stiff enough and from the vertical tail itself bending. You get flutter when a rudder movement causes the tail lift to change, which causes the tail itself to move sideways. That sideways motion couples into the rudder, causing more rudder defleciton, more fin motion etc, until the tail stiffness can balance off the lift loads. The tail stops moving, the rudder catches up, and the tail springs back the other way.. etc. etc.

So, the R54 is a stiff, low aspect ratio vertical, and its pretty solidly tied into the tail with a pretty stiff tail boom, all of which will help avoid flutter. The relatively small rudder also helps. And, it does not go THAT fast. (ANYTHING will flutter if you shove it through the air fast enough!)

OTOH, some fiberglass body jets have a vertical that can flex quite a bit, so they are prone to flutter even with good servos and good linkages. The usual culprit is fuselage flexing near the rudder attachment. You really need a couple of full ring bulkheads back there to connect the vertical tail to the fusealge skin.

Bob

afterburner

My Feedback: (18)

Bob,
That is an easy to understand description on how flutter is induced and what features of an aircraft can contribute to, or reduce it. Thanks.

Marty

BruceTharpe

My Feedback: (1)

I think the way the rudder cable swoops in its routing allows just a hair of movement of the cable within the housing. Much as I wish it was rock-solid perfect, I considered it adequate for this design for all the same reasons Bob pointed out earlier. I can certainly understand your concerns about flutter, considering you have seen it happen on other jets. No reports of flutter from any R54 builders so far (knock on balsa wood )

afterburner

My Feedback: (18)

Bruce,
I think that's exactly where it's happening as when moving the rudder by hand, I can hear it moving in that section. I don't plan to be the first reporterer of flutterer. I guess I needed just a bit of reassurance. Thanks.

Marty

rcguy!

My Feedback: (69)

No flutter on mine ever! Even at 163MPH is a WOT extended dive! Pretty much box stock except for the tank. Same servos, pushrods, etc. Just do as Bruce shows in the manual.

Dave Rigotti

afterburner

My Feedback: (18)

Dave,
I keep your video on my desktop for inspiration!

I have followed the directions to a "T". Building this kit inspires confidence in how well thought out the assembly process and design is executed. You can tell from the minute you open the box and start looking through the manual that Bruce is a perfectionist.

Marty

bobparks2

My Feedback: (1)

I design airplanes for a living, and I love building. For me, the really enjoyable and relaxing kits are the ones where I do not feel I need to re-engineer everything, and the R54 is one of the best quality kits I have ever done. Its certainly the best ever of the wood kits.

Now, I just need enough time to get it finished!

bob

mr_matt

My Feedback: (10)

Hi Bob,

Is it safe to say that for a (theoretically) infinitely stiff fixed surface, the movable surface CANNOT flutter, at any speed, even without a linkage?

Thanks

bobparks2

My Feedback: (1)

No, there are some flutter modes that could still happen. There can be some non-linear aero for example. (transonic or low RN, or a hysteresis loop near surface stall). Another issue would be unsteady aerodynamics, where the surface could move significantly during the time it takes for a given chunk of air to flow past it. So, your case would be pretty good, but there are still ways it could flutter under some conditions.

One good example of the case you mention is a weather vane. No linkage, stiff mount, and if the mount is truly stiff and vertical axis, it will not flutter even with no balance weight.

BTW, what a balance weight will do is decouple two degrees of freedom in the system. For example on ailerons, the typical two degrees of freedom are wing up and down flapping, and the aileron twisting motion relative to the wing. If the aileron is perfectly balanced about its hinge line, then it wont rotate as the wing flaps, and no flutter.

Now the definition of "perfect balance" changes according to the surface bending mode. On a rudder, you can have a side to side wiggle of the tail, or you can have the whole aft fuselage twist. For the first, the spanwise location of balance weight is not critical, since it all moves the same. For the second, the tip as more motion than the root, so balance weights at the tip are more effective than weight at the root.

Bob

BalsaBob

My Feedback: (24)

I am finishing up my R54 and will soon be painting it (it is all glass cloth covered). I am considering using BVM Heat Shield ceramic paint above the turbine (instead of the thin steel/metal sheet). Wondering if anyone has had success with this ? Thanks. Bob