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[Guest]

For Enstrom Users. (My first helicopter to fly was in a Enstrom 280C. Great for autorotations.)

 

-Rey

[Ga. Chopper]

Roger on the fantastic autorotaion characteristics, I do autos almost every flight because they're easy and fun!  :thumb:

[RDRickster]

I've only got a few hours in the 280FX, but I found the autos to be more work than other helicopters (excluding the R22).  The Enstrom has one of the best flying characterstics in foward flight, but the auto was not as smooth as I thought it would be.

 

In my opinion, for a helicopter that claims the following...

 

A high inertia, fully articulated rotor system provides an unusually stable ride and exceptional autorotative capabilities.

I wasn't impressed.  High inertia?  What's their definition of high inertia.  The rotor RPM is pretty easy to manipulate with collective... almost as much as the R22!  That's not my definition of high inertia.  The B2B has the hands-down best auto, followed closely by the B47.

 

Like I said, it has fantastic handling capabilities in forward flight, and I love the automatic trim.  In fact, the Enstrom is sooooo stable, I was able to take my hands off the cyclic!  You could almost change heading by leaning inside the cockpit to the left or right... completely with your hands off the cyclic.  Obviously, a very stable platform.

 

However, it flies like a PIG whenever you get out of trim.  Auto's seem to require much more right pedal than the R22, B47, and B2B's I've flown.  I suppose one reason for the unusual aerodynamic qualities is the boat-like shape of the fuselage.  You really seem to "catch air" during flares.

[Ga. Chopper]

RDRickster,

 

Enstroms definely have more inertia than a B2B by a long shot. Interia has nothing to do with trim or the amount of rudder you have to apply during an auto. The only piston helicopters that have high inertia like the Enstrom are the R-44, Bell 47 and the Hiller. The Hughes/Schweizer are between those and the R-22. I have seen the the specs on these helicopters to validate this.

 

First of all, inertia is the amount of energy the rotor system has after the engine power is taken away. The rotor system of an Enstrom weighs about 300 lbs. and has about 4 times the inertia of a R-22. In a Robbe, you have about 1 second to lower the collective after you chop the throttle or the rotor RPM will quickly bleed-off and develop into a unrecoverable low rotor RPM. That is not case with the Enstrom because of the higher inertia, the rotor RPM does not quickly bleed-off; and a low rotor RPM condition can also be safely recovered.

 

The rate of descent during an auto is sustantially lower and gives more time to safely accomplish the manuever. Hovering autos also have much more "hang-time" in an Enstrom because of the higher inertia.

 

The tail rotor authority is also very effective in the Enstrom and LTE is not much of a factor. The rudder pedals are almost neutral in a hover which demonstrates this versus using alot of left pedal in some other helicopters. Therefore, the right pedal must be pushed almost all the way in to take away the anti-torque effect during autos.

 

As for the trim, most low time Enstrom pilots over trim using the "coolie hat" due to it's very fast and sensitve nature, plus they wait too long before inputing any trim so they over correct. The secret to flying the Enstrom is to just bump the trim as you transition into and out of forward flight. For example, when you transition into forward flight you just bump the trim switch forward and right, then forward and right a few times and you're done. Same idea when you transition into an approach and hover, but opposite with the trim switch: aft and left, then aft and left a few times. Once you learn to anticipate these movements with trim switch and not wait too long or hold the switch too much; it's easy.

 

If you don't accomplish this trim procedure correctly, it does feel heavy on the controls. But if this happens, use the trim reduce the stick force and don't fight it!!! When manuevering in a hover or hover-taxi, you pro-actively fly with the trim.

 

Once you learn these techniques, flying the Enstrom is easy, fun and relaxing. Plus the pucker factor is less with it's great hands-off stablity and autorotation characteristics.

[RDRickster]

I could be mistaken, but I believe I fully understand the fundamental dynamics of rotor inertia.  Regardless of the ROD, flow effect, and approach angles of the 280FX in autorotation, I found that the RRPM was not as stable as the B2B.  The B2B's rotor head ALONE weighs 4 times the R22 system (with blades)!  Therefore, I believe it is a bit heavier than the Enstrom's... but I could be wrong.

 

In the late generation B2B I've flown (Kevlar clutch, new components, etc), the autos were absolutely smooth... lot's of air time... very gentle... absolutely no change in RRPM... slow ROD... the very best autorotations I've every experienced.  Of course, given my limited experience that doesn't say much.  In contrast, I found the RRPM management in the 280FX requires more attention than I originally thought it would.

 

Don't get me wrong, the 280FX autos are still more gentle than the R22.  That said, the B47 autos are pretty darn smooth, too.  I wish we could take the very best from each helicopter, and build a new hybrid with some newer technology.

[Ga. Chopper]

RDRickster,

 

I don't know anything about the new generation B2B and have only flown a little bit in the older B2B. I did not remember the older ones being anything like they evidently are now.

 

I don't understand why you had difficulty in maintaining MR RPM, I have never experienced that in the 3 different piston Enstroms that I have flown. In mine, I just bottom the collective and the MR RPM stabilizes at the top of the green band, unless you load up the rotor system such as with 180 degree autos. Maybe the 280 FX you've flown is not properly rigged.

 

I would be surprised if the B2B has a heavier/higher inertia rotor system than the Enstrom because I have seen published fiqures where the Enstrom is about the same as an R-44. But I have not seen any for the B2B.

 

Everyone in our helicopter club is impressed with the autos in mine, especially hovering autos.

 

I agree with you, too bad someone can't incorporate the best of all these machines into one new design.