New engine?
 

Earlier in this thread, there was discussion about the Robinson engine and the advantage of having a lighter one.

Perhaps Robinson is considering the new Bombardier V-6 aero engine. A 220hp, normally-aspirated version, and a 300hp turbo. Bombardier claims, "...the best power-to-weight ratio in aviation technology.". There has also been mention of 2,000 TBO and FADEC

I am sorry if this is drifting a little off the actual thread but, can anyone explain this,

FR makes great play on the point that the R22 is NOT designed, built or supplied with, or for any sort of training purpose, now if this is expanded a little, Why do FTO's use the R22 as a basic trainer, expanded this little more,( this has to be lateral thought) we are informed of quite a lot of accidents and sad fatalities in connection with the ubiquitous little heli being used by student and low timers, the aftermath is always picked up and sorted out by the companies who insure the FTO's, is there not some conflict here,... Ie, FR says Not a Trainer, but XYZ insureres cover the heli for training! where and who holds the Duty of care, that provides this ability and permission to use this R22 type to train new pilots.

If the R22 in my opinion is going to be used to train people, and is accepted by insurers as safe to do so, then why does FR try to steer away from this point! what does this gain him?

Peter R-B

Put the blame on Mable.
 

To: Vfrpilotpb

It gives him a sort of absolution while placing the blame on the pilots’ actions while not addressing the real problem, which is the design. (Read Rotorhead).

:E

Hi all,

if you say "Loss of control", do you mean loss of control by the pilot, like in flying into bad weather, clouds, getting all worked up and loosing it or freezing on the controls (saw that too...) or loss of control due to mechanical failure like mechanically frozen controls, blade/rotor separation, etc.
Note: I do not consider a Tail boom separation after a pilot error a mechanical loss of control. In this case the pilot lost it long before!

That Robinson requires every dealership to be a training center is logic. If you sell a machine that is generally sensitive, you want to make sure that the future owner is able to handle it. I understand that any Helicopter dealer would provide transition training to their product. Robinson doesn´t say, that you have to have a flight school for initial and advanced helicopter training.
I understand Training Center refers to Robinson transitions, aircraft ground handling, etc.

He would be nuts if he allowed anyone to sell his aircraft without providing that training!

All I wish for would be a passiv electric trim system in the R-22. Getting old and wishing for more comfort!

AND more emphasis on correct handling of the R-22 by schools, incl. respect for the limits published, like weight!!

Cheers,
3top:cool:

Some one asked at the very beginning what they would do to improve the Robinson line?
The only two things that come to mind as anywhere near 'essential' are a 'normal' type of cyclic, and change the engine and rotor RPM gages to something like the rest of the world uses - the crossing needles must take a considerable amount of time to get used to.

Did anyone ever consider a hub spring, as was done for the AH-1Cobras - I know this would transfer the problem somewhere else, like the top of the transmission, but it might be worth considering.
A good simulator at low cost would help a lot - the Fly-it one comes close but could stand more tweaking.

Is it or is it not a training helicopter?
 

To: 3Top


QUOTE: That Robinson requires every dealership to be a training center is logic. If you sell a machine that is generally sensitive, you want to make sure that the future owner is able to handle it. I understand that any Helicopter dealer would provide transition training to their product. Robinson doesn´t say, that you have to have a flight school for initial and advanced helicopter training.

RESPONSE; If this is the case then why does Frank Robinson state that it was not designed as a training helicopter whenever there is a fatal crash? Especially, if it involves loss of control.

To: Shawn Coyle

When Bell upgraded some AH-1 series helicopters they went from steel bearings on the teeter trunnion to Elastomeric bearings. I do not believe these bearings would qualify as hub springs. However on the AH-63 that competed against the Apache the rotorhead had elastomeric bearings that had such high resistance to torque (teeter) that they qualified as hub springs.


:E

Shawn,

The Good ~ A hub spring will assist in keeping the rotor disk normal to the mast. This is especially beneficial when the disk is unloaded.

The Bad: ~ If the helicopter has only two blades, a 2/rev. vibration will be created. when the disk is tilted.

More information on Hub Spring


Lu,

Here's a little thought provoker for you. ;)

Rotors will resist negative coning to some extent because the lowest collective pitch on most is approximately plus 1-degree. Even this small amount of positive pitch should oppose negative coning. An exception to this would be when the craft was subjected to negative G's, which resulted in a collective negative angle of attack.

In addition;

The offset flapping hinge rotors will resist negative coning because of their offset flapping hinge and the centrifugal force on the blades.

The teetering hinge rotors have a pre-cone of 2 to 3-degrees in the hub. This combined with the structural strength of the blades will help resistance negative coning.

An exception to this might be the Robinson. It does not have an effective offset flapping hinge nor does it have a structural pre-cone. :E ;)

Negative cone. No ice cream in it.
 

To: Dave Jackson

Dave I don't know if I completely follow you. Not because of you, but because of me. After all, I am an old man.

The Robinson can not achieve a negative cone as the blade can not pass through its' static or radial position. The downward movement of the blade about the cone hinge is restricted due to the spindle tusk making contact on the droop stop.

It is this element of the design that can cause problems. Any force mainly flapping excessively will cause the spindle tusk to strike the droop stop and result in the spindle tusk fracturing and the blade is then free to make contact on the fuselage.

This same phenomenon can result in mast bumping if the contact force is strong enough and the tusk does not fracture.


:E

Lu,

Your correct about the spindle tusk. I forgot that the Robinson has static droop stops, and not dynamic ones that move out of the way.

The same concern still applies though. It appears that the Robinson hub may be more inclined to want to go into negative coning than do conventional teetering hubs (with their pre-cone) and fully articulated hubs (with their blades' desire to align with the mast plane).


While trying to provoke a fight with someone, I might as well pick on Prouty, also. :O

Prouty says; " On his R22, Frank Robinson has installed separate blade flapping hinges in addition to the hub teetering hinge. This achieves the same result as the Bell flex-beam while reducing blade-root bending moments ...."

It appears that the Bell 412 flex-beam hub has virtual flapping hinges. These flapping hinges must be offset from the center of the rotor. Therefor this 'offset' should result in the rotor acting more like a conventional fully articulated rotor than the Robinson's tri-hinge rotor.

:E :E

Flex muscles not beams
 

To: Dave Jackson

What you say about the 412-rotor system is true. Because there is a virtual flapping hinge the disc plane will vary from the pure radial position relative to the rotorhead and as such will lead and lag. To accommodate the lead and lag the rotor head is “soft in plane” which allows controlled leading and lagging.

On the Robinson head under ideal conditions the blades will maintain their coning angle relative to the head. However the aerodynamics of the head are such that the blades can as required flap on the cone hinges independent of each other. When the blades flap there is lead and lag. However the lead and lag is restrained and the forces generated are reacted mainly by the cone hinges ,the mast and the blade root.


:E

A better R22?

Enstrom almost did it but blew it (literally),when they bolted on a turbocharger in search of a real third seat. The original 28A has three fully articulated blades, lovely docile handling, and two up, performance very similar to R22. It cruises at 21", 2750 rpm and 80mph, so is not all that overstressed. It has a real stick and looks like it is finished! It has an exemplary safety record. Unlike Robbie, there has never been a fatality caused by mechanical failure. It has very few lifed componants. Even the main rotor blades are not lifed.

This seems to fill most of the desired criteria.

It is also too heavy, too thirsty and considered a pig to work on but it is a 40 year old design. There is considerable scope for lightening and improving it using modern materials and design techniques.

Enstrom turned out 100 plus aircraft a year until the turbo was added. Then they could only manage 10 or so. Had it been lightened and developed specifically as a 2 seat trainer it could have cornered the market. As it was, Enstrom effectively vacated the trainer market in the late 1970s in search of the 'executive' market, leaving a vacancy for Frank.

A turbine is always going to be too expensive for a basic trainer with an Allison 250 costing about 10 times as much as a Lycoming. Look how much a 480 costs which is basically a stretched version of the F28 with a turbine chucked in.:eek:

My beer mat design would be a 2 seater with Enstrom dynamics. A 230 BHP SMA flat four diesel would replace the Lycoming. Not too heavy. No Avgas. No 12 year rebuild and not underpowered or overworked. It would probably be costlier than an R22 unless built with cheap far east labour.

Maybe that's why Enstrom have started a new facility in Wuhan province, China.

Watch it, Frank!


I have more hours in R22s than Enstroms.
I own a lovely old F28A which I prefer to the R22.

Have one question... How many of the so called loss of control accidents have occured in the R44... apart from the original in El Monte??? (Very few I bet.)
Have been out of Robinsons for years but the debate has become like a skipping cd. Have about a thousand hours in the R22 and the same in the 300 (all instructing)... I have to say they are both great helicopters. If I was buying one for personal use, the R22 would win hands down.

Shawn,

With respect to the 'crossing needles'. To me, they are a great way to present the RPM information. (Admittedly, I've been looking at them since my first helicopter flight, so they would seem natural !) Reading them is, to me, instant and unambiguous. Crossed or split, it's easy to see on a scan and either ERPM or RRPM is easy to read.

Obviously, it's what one is used to - I've had a few hours in other aircraft during which I had great problems with the concentric presentation. I found myself actually having to look at and read the pointers & dial, rather than just being able to scan and assimilate. Silly, I know, but my mind kept posing the question: "am I looking at two pointers overlaid, or just the one ?"

Enstrom
 

Gaseous,

Could you give some more insights as an Enstrom owner, I will look into the possiblity of buying an older ship.
I have bought many older aircraft, damaged or out of annual for a low price then fixed them and did cosmetic repairs as I flew them, then sold them at a price that pretty much covered the cost of my ownership.
Might do that with an Enstrom.
What is the price range of old Enstroms?
What are the life components or other major costs?
How does the manufacturer treat you when ordering parts?

Thanks for any info you can provide.
slowrotor

Slowrotor,

Owning and operating an old Enstrom, for me has been a joy. I use it for fun, and fly mostly short hops to friends and local hotels. It lives in my garden with a full cover over it.

The non turbo 28A and 280 start at about £40k in flying condition.
The sort of approach of buying a tatty one and doing it up is exactly what I did and it now looks rather smart. I'll e-mail you a picture.

Insurance is cheap (compared with R22) as it is based on value. There is no problem with most mechanical parts as many F28A parts are still used on new aircraft. U.S. Dealers are good for new parts. There are a few scrap F28s about for the other bits.

Parts Lifed to scrap
TR flexpacks
TR gearset
TR spindle
MR shaft
assorted bearings
tacho drive belt

Parts Lifed to overhaul
Engine
mags
fuel injector
clutch
MR gearbox


All blades are 'on condition' - no life limit. Check for debonding. Repairs are acceptable. Good second hand main blades are about £1000 to £1500. Lamiflex head bearings are 5 year items (U.S.$3600 for the set). The main rotor shaft has 19000 hours life! ( how do they work that out??)

Find an engineer who likes them - many don't.

It uses 11-12 U.S. gallons per hour- Turbocharged aircraft carry more weight but the engines are overworked and never reach TBO of 1500hours. Consider a non turbo as a 2 seater plus very small child. Forget it for hot and high. Performance is similar to R22. Handling is docile but remember that Dennis Kenyon has used Enstroms for his stunning aerobatic displays. With the trim set carefully it will fly hands off for about 30 seconds. Try that in an R22! There is no governor and many have no correlator. This is not a problem, in fact it adds to the fun. Autorotation is undramatic.

As with all aircraft, especially old ones, get a survey done and be very careful!. Expect problems - if you don't get them, be very happy.

Gaseous