The mysterious sign in Bell Helicopter's exhibit space today at the Army Aviation Associaton of America's (Quad-A) convention simply reads: "It's not a tiltrotor ... what is it?"
It is Bell's candidate for replacing both the AH-64 and UH-60 with an all-new configuration called the Hybrid Tandem Rotor, Robert Kenney, Bell's executive VP for government programs, told me in an interview a few minutes after I filmed this clip.
The HTR "splits the difference between a helicopter and a tiltrotor," said Kenney.
While the BellBoeing V-22 can tilt its tandem rotor 95 degrees, the HTR's wing tilts by 25 degrees and gains 5 degrees more by adjusting the cyclic controls.
That means the HTR could achieve a forward speed of 225kts, Kenney said. A V-22 cruises at more than 300kts, while the fastest helicopters are limited to about 170kts.
If this particular configuration has ever been attempted before, Bell's engineers are not aware of it.
"When I first saw it I tried to figure out why it was a bad idea," said Kenney. "And I peppered the poor designers with questions and they answered them all. And then my question was 'why hasn't anyone tried this before?' Now that you see it it's kind of a no-brainer."
But don't expect to see a prototype flying any time soon. Kenney said Bell has no plans to launch a prototype demonstrator. The HTR will remain a design concept only unless the US Army launches a competition to replace the AH-64 and UH-60, he said.
That notional program, known as the Joint Multi-Role (JMR) requirement, exists, but has so far not been funded to enter a long-term development phase. According to Kenney, the army is more likely to continue improving its existing aircraft fleets, rather than develop an all-new aircraft.
By exhibiting the HTR at the Quad-A convention, Bell simply hopes the concept sparks the army's interest.
"This is kind of it's coming out party," said Kenney, "so we'll see what the interest levels are."
It is Bell's candidate for replacing both the AH-64 and UH-60 with an all-new configuration called the Hybrid Tandem Rotor, Robert Kenney, Bell's executive VP for government programs, told me in an interview a few minutes after I filmed this clip.
The HTR "splits the difference between a helicopter and a tiltrotor," said Kenney.
While the BellBoeing V-22 can tilt its tandem rotor 95 degrees, the HTR's wing tilts by 25 degrees and gains 5 degrees more by adjusting the cyclic controls.
That means the HTR could achieve a forward speed of 225kts, Kenney said. A V-22 cruises at more than 300kts, while the fastest helicopters are limited to about 170kts.
If this particular configuration has ever been attempted before, Bell's engineers are not aware of it.
"When I first saw it I tried to figure out why it was a bad idea," said Kenney. "And I peppered the poor designers with questions and they answered them all. And then my question was 'why hasn't anyone tried this before?' Now that you see it it's kind of a no-brainer."
But don't expect to see a prototype flying any time soon. Kenney said Bell has no plans to launch a prototype demonstrator. The HTR will remain a design concept only unless the US Army launches a competition to replace the AH-64 and UH-60, he said.
That notional program, known as the Joint Multi-Role (JMR) requirement, exists, but has so far not been funded to enter a long-term development phase. According to Kenney, the army is more likely to continue improving its existing aircraft fleets, rather than develop an all-new aircraft.
By exhibiting the HTR at the Quad-A convention, Bell simply hopes the concept sparks the army's interest.
"This is kind of it's coming out party," said Kenney, "so we'll see what the interest levels are."
on May 5, 2009 12:35 PM | Reply
Intriguing concept, but I don't understand how the "tandem" part of the name applies.
on May 5, 2009 12:36 PM | Reply
Ummm... doesn't tandem mean one behind the other?
on May 5, 2009 12:40 PM | Reply
Maybe it depends upon your perspective?
on May 6, 2009 3:11 AM | Reply
It's not a tandem - the rotors are laterally disposed so its a side-by-side configuration. To call it a tandem is either engineering stupidity or a marking ploy. The concept seems like a semi-tiltwing / semi-tiltrotor. Why only go half way on either concept? It then ends up with the disadvantages of both, and few of the advantages of either. Third, it will still have the poor hovering efficiency of a tiltrotor or tiltwing (hanging the entire weight of the aircraft on two small proprotors of high disk loading is just never a good idea). Think about the brownout problems with this concept compared to a UH-60! Fourth, it only has a marginal speed advantage over a pure helicopter. The helicopters of the future will cruise at over 200 kts because they will have been properly DESIGNED not guessed at by engineers from a company who's best helicopter product in 40 years is a rehash of the vintage Model 206. Last one out please turn off the lights.
on May 7, 2009 8:40 PM | Reply
I can see one advantage over a true tiltrotor is simplicity of the tilting mechanism. The entire wing/engine/cross shaft/gear boxes/rotors move as a unit.
I can also see one huge disadvantage. The V-22 suffered from Vortex Ring State during high descent rates. The recovery method discovered is to momentarily translate the nacelles.
The V-22 can do this. With it's limited tilt range, could this tilt wing do the same thing successfully?
on May 9, 2009 7:30 PM | Reply
I would have found it more interesting if the jet engines provided forward/horizontal thrust, and yet had a "clutchable" drive shaft for the rotors - as in the F-135 engine for the F-35B. During forward flight, the rotors would basically be free-wheeling like that of a gyrocopter. This would be more like that of the Gyrodyne concept with a new twist - direct drive of dual counter-rotating rotors to counteract torque instead of using noisy tipjets on a single rotor.
Of course this might bring up another option that has apparently been considered by LM - slap an F-35B's engine and thrust vectoring system, including the fan, on either side of an airframe and get...an instant flaming LZ...Oh well.