• Hi Guest! Forum rules have been updated. All users please read here.

Boeing Vertol Model 347 (HLH) : A Chinook with wings

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
288
Reaction score
0
Website
www.freewebs.com
A Chinook with wings?

http://stinet.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0909933

Abstract : The US Army Aviation Systems Test Activity conducted the Phase II technical evaluation of the Boeing-Vertol Model 347 winged helicopter during the period 3 through 11 April 1972. The Model 347 winged helicopter, a derivative of the CH-47 transport helicopter incorporating a variable incidence wing with normal acceleration load-sensitive flaps, was tested at the contractor's facility near Philadelphia, Pennsylvania. The evaluation was conducted to determine the improvements provided by addition of a wing system to a transport helicopter. Compliance with the provisions of military specification MIL-H-8501A was determined. Evaluations of the variable incidence wing system and the retractable landing gear system were also made. With the wing in the hover position, out-of-ground-effect hover performance of the Model 347 winged helicopter was similar to the unwinged aircraft. Both the winged and nonwinged Model 347 helicopter could hover out of ground effect using less power than could the CH-47C. Level flight performance at a heavy referred gross weight (54,000 pounds) was improved over both the nonwinged helicopter and the production CH-47C. Addition of the wing to the Model 347 helicopter did not significantly change the generally excellent handling qualities reported for the nonwinged version of the aircraft. The strong longitudinal stability exhibited by the aircraft reduced pilot workload in maintaining trim airspeed and pitch attitude. Only minimal trim changes in all control axes were required when transitioning between climbs or descents and level flight. (Author)

Anyone seen any pictures?

Cheers, Woody
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
1,963
Reaction score
62
Pictures like these? :)

It has been repainted and is in far better shape than it looks in these pictures.
 

Attachments

Matej

Multiuniversal creator
Joined
Feb 13, 2006
Messages
2,617
Reaction score
30
Website
www.hitechweb.genezis.eu
Eh, helicopter with the tilt wing?? What is the reason for that? I mean - is the air flow so important, that it is more valuable than tilting mechanism, additional weight, less structural integrity, etc... ?
 

elmayerle

CLEARANCE: Top Secret
Senior Member
Joined
Jan 8, 2006
Messages
1,251
Reaction score
5
If you tilt the whole wing, the structure and mechanism isn't that complicated, comparatively, and it works for the benefits the wing gives you in cruise.
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
1,963
Reaction score
62
Matej said:
Eh, helicopter with the tilt wing?? What is the reason for that? I mean - is the air flow so important, that it is more valuable than tilting mechanism, additional weight, less structural integrity, etc... ?
Indeed the air flow is a significant issue. The downwash of the rotor driven air onto the wing is very undesirable. If you note most attack aircraft have very small wings that are used more for weapon storage than lift. The Russian designers seem to be less concerned than western designer though (Mi-24 and Ka-50/52). Large wing area under the rotor systems requires more power to conduct vertical take off. By tilting the wing of that size there is a significant decrease in the power required for the helicopter to take off and land.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
288
Reaction score
0
Website
www.freewebs.com
Great, if unnatural looking, pictures. Doesn't seam to be much clearance between the front rotor and the wing 'hump'.

Woody said:
Both the winged and nonwinged Model 347 helicopter could hover out of ground effect using less power than could the CH-47C.
Why would it (winged and nonwinged) use less power in hover? Were there other modifications?

Cheers, Woody
 

yasotay

CLEARANCE: Top Secret
Senior Member
Joined
Oct 19, 2006
Messages
1,963
Reaction score
62
I wrote poorly... :-[

Certainly the aircraft with wings will take more power than one without. For this particular aircraft I would note that it also has a four bladed rotor system, vice the normal three bladed system. I do not know if the aircraft had more installed power than the CH-47C which would also account for improved lifting power.
 

Woody

Passionate about the advancement of technology
Joined
Mar 8, 2007
Messages
288
Reaction score
0
Website
www.freewebs.com
yasotay said:
I wrote poorly... :-[
You wrote perfectly. I was querying the DTIC article I originally posted. Why if the aircraft had better performance even without the wing did it not get adopted as the new CH-47? I didn't even notice the 4 blade rotors which brings me to another thought: I guess it depends on size and spacing but I believed that 3 blades per rotor were the most for a tandem helicopter. Is there an upper limit? How many did the XCH-62 have?. Maybe they could try ones like on the Superstallion ;D.

Cheers, Woody
 

Attachments

Jemiba

CLEARANCE: Above Top Secret
Staff member
Top Contributor
Senior Member
Joined
Mar 11, 2006
Messages
7,990
Reaction score
144
At least, this project got as far as building a technology demonstrator
(from Aviation Week 1974_1-13)
 

Attachments

Stingray

Brony rotorhead...
Joined
Nov 30, 2007
Messages
384
Reaction score
3
Website
sites.google.com
The Model 347 was a CH-47A with a stretched fuselage, hydraulically-controlled lift-wing mounted above the center of the fuselage, and four-blade rotors. It served as a technology demonstrator in 1970 for the Army's HLH program.

It also had a small gondola for the winch operator that retracts into the belly, just behind the cockpit.

Photos below from Ray and the USAAM archives:

http://stingraysrotorforum.activeboard.com/t26318430/boeing/?page=4
 

Attachments

Kryptid

CLEARANCE: Secret
Joined
Mar 13, 2009
Messages
275
Reaction score
1
Website
www.facebook.com
I find it interesting when I see helicopters with wings.

Obviously, they don't contribute to the VTOL capabilities of the aircraft; are they usually placed there to improve lift in forward flight and therefore possibly increase range? Admittedly, I don't know much about helicopter aerodynamics when compared to fixed-wing aircraft.
 

AeroFranz

CLEARANCE: Top Secret
Senior Member
Joined
May 4, 2008
Messages
2,157
Reaction score
18
short version is yes, if you can unload the rotors by supplying wing lift, you can delay issues due to advancing blade drag and retreating blade stall, the bane of rotors. You can increase speed (a little bit) and improve your lift-to-drag ratio (more range).

Thanks for the pictures!
 
Top