Many people have voiced opinions about the R22 and to a lesser degree about the R44. Some times these opinions are positive sometimes they are negative, but regardless they are allways strongly held. I have often wondered about peoples perception as to what the REAL problem with Robinson helicopters is, some of our contributors would say its the light-weight two-blade teetering rotor system, [with or without 18-degrees of d3
] others will complain about lack of payload, speed, crashworthiness, cabin space, the t-bar system, the list goes on....
However, virtually all of the R22's [and in general the R44's] characteristics/vices can be be traced to one simple problem and in understanding this problem we can really marvel at the technical excellence demostrated by Frank Robinson.
The problem with the design of the R22 [and the R44] is this: THE ENGINE IS TOO HEAVY.
Taking the R22 as a case in point: the R22 has an empty weight of 389kg, the Lycoming O-360-J2A, installed in the R22 has a dry weight of 120kg this is 30% (a whole third!!!!) of the empty weight of the helicopter!
With this much of the weight budget invested in carrying de-rated engine mass around then very little is available for the airframe. Hence, Robinson was forced to compromise on the weight available for other components and payload. This requirement led to the use of the lightest possible rotor system, only two blades and no additional dead-weight [read inertia]. There was no weight avaialble for crumple structures or robust under carriage. Nor was there any weight available for toughening the airframe against fatigue and wear substantially, hence the relatively short lives of many of the compoents compaired to larger machines.
Robinson solved the key problem of of small helicopters of that time (Hughes 269 and Enstrom F28) which was the poor relability of there over-taxed engines, but in doing so created additional difficulties for himself.
The key point in this post however, is that he did a remarkable job of balancing the requirements and created a new industry in doing so. The R22 is very close to the best that can be done, if you want to achieve cost effectiveness and reliability with a Lycoming type engine. Yes a light helicopter with robinson reliability could be designed with a higher inertia rotor system - but you would carry less payload, or have parts to replace after only 1000hrs. As Nick says; 'There's no free lunch.'
Simply stated, the problem that faces light helicopter designers is not a helicopter technology problem, as there is certainly a large gap between light helicopters and bigger helicopters in terms of performance and safety [i'm NOT refering to engine failure rates here Frank!] the problem is engine-technology....or lack of!
The helicopter is one of the most demanding applications for torque-producing enignes. Helicopters have very strict requirements on power-to-weight ratio's as an extra kilogram of engine is a kilogram of payload that cannot be carried. In addition helicopters (single engined one's at least) operate at high power setting virtually all of the time.
With this in mind what Robinson has done is to raise the bar somewhat because if someone is going to design the next generation light training helicopter and entry level commerical helicopter that addresses all of the short comings of the R22, while simulataneously reducing the direct operating cost then you need a better engine. If you don't then you may improve one aspect, but another will suffer. A good example of this is the Guimbal Cabri G2, a french designed light helicopter that appears to be lost somewhere in the certification process at the moment. Lycoming powered, composite fuselage and 3-bladed elastomeric MR with a relatively good aerodynamic design. This aircraft will fly faster than R22, but will cost more and still have painfully limited payload. Will it sell.......we will have to wait and see but my guess is no....it'll be another Enstrom/Schweizer becuase in the training and entry level markets cost-is-king!
What do I think of Frank Robinson & his achievements?
Remarkable. Truely.
The R22 is a fantastic machine and the R44 is better. Robinson took an extremely difficult problem and has provided a compramise that is as close to the optimum as you can get when considering all apsects of a real helicopter. I would bet my mothers teeth on the fact that no-one designing a Lycoming powered helicopter will ever conquor robinsons market dominance.
I only have one real complaint about the way the R22 & R44 have been designed and that is that the tail rotor is too high. The R22 has a very low CG and when this is coupled with a high TR it causes the right roll in low-g flight to be exceptionally agressive. If the TR were on the CG centreline or closer to it then the R22 would not role so aggressively upon inadvertant entry into low-g. Once again this was a comprise - lower TR more tail strikes!
Could I design and build and better machine with similar capital and DOC?
Yes...
Have I ever flown Robinson's?
Yes, lots......i'm a big fan.