SH-60B push-prop moded by Kaman, now with video

[Dan Reno]

Recall seeing a pic of Kaman adding a push prop / fan to a SH-60B Seahawk some time back but can't find anything on it nowadays. Anyone know what the status of that project is?

[maxtork]

Work on that was being done by Piasecki and I heard at HAI it was going to test very soon on the east coast somewhere. It has been pretty quiet though.

Max

[NickLappos]

Frank Piasecki is a real genius, and his twin rotor machines created the current Boeing Helo company. He is very smart and very funny - his daughter is a crackerjack engineer who helped a bit on the early LHX research projects.

However, Frank's "Pathfinder" was a re-treaded idea to add the pusher prop (instead of a tail rotor!) and get extra speed on a Hawk. He personally lobbied the local congressman, and got a bill passed to get several millions and an airframe, and then the Navy got saddled with the project. Dozens of press releases later, the program was taken over by the Army and then quietly smothered to death.

Winged compounds are not particularly new, are very well understood, carry much less payload over less range (but at somewhat higher speed) than a helicopter, and have never created a market for themselves. Each manufacturer has built real research compound helos, tried the concept and then dropped it.

Like the Notar, the Pathfinder is a testiment to the lack of technical understanding of the media, so that any idea is presented, unchallenged, in the PR agent's own words.
Here is an artist's sketch of the Hawk Pathfinder, on Piasecki's web site. There seems to be no mention of the program at all on the site, butthere is a good biography of Frank:
http://www.piasecki.com/index.html

[maxtork]

Hey Nick,

Didn't Sikorsky play with an S-61 with a tail rotor that swiveled to point aft and become a pusher? I know the wings would still get in the way of the rotor downwash in a hover but was the swiveling tailrotor design better than the ducted fan idea of Piasecki as far as effeciency?

Max

[NickLappos]

Yes, the old S-61F was flown about 2 years before I joined Sikorsky, and it had a wing, a jet engine and a swing-tail rotor at various times in its research life. The swing tail was a moderate success, but the combination added about 20 knots, and robbed exactly enough payload to be a net loss.

Here is a site that discusses the 61F (note that the speed it quotes is with the jet compound engine):
http://avia.russian.ee/helicopters_eng/sik_s-61f.php

Wings are a real problem, thay can cost 10% of the gross weight in lost payload due to "vertical drag" which is kind of the dark cousin of Notar's coanda effect. The wings sit in the high speed downwash and create a download that is awesome. That is why the various tilt wing concepts have been tried, to get the wing aligned with the downwash and reduce the vertical drag. As an example of how vertical drag is a factor, for the small nose on the Shadow, we measured a loss of 150 lbs of payload just for that nose bulge:

http://avia.russian.ee/helicopters_eng/sik_shadow.php

[Ian Corrigible]

Looks like the 'Speedhawk' is being readied for ground testing. See http://avtoday.com/cgi-bin/html2xhtml.cgi?url=http://avtoday.com/categories/rotocraft/9926.html.

I/C

[maxtork]

Well the Army may have some extra pennies in their wallet if the ARH goes south! Interesting design anyway. I would be interested to see if this evolves into some kind of "swing wing" design ala F-14 to get the wings out of the downwash at a hover. Of course that adds complexity as well.

Nick,

You said the swiveling tailrotor only gained about 20kts. I was suprised to hear that as the cheyenne was pretty fast using just a pusher prop. I guess I figured that a larger aircraft like the S-61 with lots of tailrotor authority would have a greater effect as a pusher. Anyway thanks for the info!

Max

[Aser]

Here is the old pic.
http://i66.photobucket.com/albums/h263/aser_martinez/1024_6139303531663938.jpg
Regards
Aser

[Brian Abraham]

we measured a loss of 150 lbs of payload just for that nose bulge:


Nick, out of interest can you quantify the loss of payload for the Blackhawk with the "wings"?

[NickLappos]

Brian,
The vertical drag depends on the wing area, as well as how much wing is under the mid-span and tip where the high velocities are. Generally, it is possible to lose 10% of the gross weight of the aircraft to wing drag (the typical helo loses about 4% or so0

The V22 probably loses 10% of its gross weight, so it suffers a 6% greater loss than a regular helo. I think you could use that 6% as a rule of thumb. 6% MGW means about 14% payload loss - 600 lbs or 3 pax for an S76, 6 pax for an S-61/92. Big deal, unless the revenue is balanced against an increase in transport efficiency.

Bear in mind that is just for the wing, the thruster/prop is an extra burden, pound for pound, since it adds nothing to the hover payload, it is a dead loss that must earn its keep in higher speed. That is why swing TR's and ring tails were attempted to replace the TR. If the combination of wing and thruster leaves 20% of the payload home, it had better add 20% to the transport efficiency to break even. That is perhaps 40knots of increased cruise speed (for the same fuel flow).

I stand corrected on the demise of the project, here is the text that Ian's link pointed to (for some reason the link didn't work):


Tuesday, March 27, 2007
Piasecki Readies SpeedHawk for Ground Runs



Piasecki Aircraft has moved its SpeedHawk compound-helicopter demonstrator to Boeing (http://avtoday.com/search/?query=Boeing)'s flight-test facility in Wilmington, Del. in preparation for ground runs in April. The modified Sikorsky Aircraft (http://avtoday.com/search/?query=Sikorsky%20Aircraft) UH-60 includes Piasecki-designed fixed wings and a vectored-thrust ducted propeller mounted on the end of the tail boom. Essington, Pa.-based Piasecki aims to achieve speeds in excess of 200 kt with the design. The company in the past developed the design with U.S. Navy funding. The latest work is being done under U.S. Army Fiscal 2007 funding.

[NickLappos]

Here is a nice video of the Piasecki SpeedHawk flying:

http://www.youtube.com/watch?v=Yu2CwHwxJYA

[ShyTorque]

S'funny - it looks just like a larger version of the 16H Pathfinder, made by..... :confused:

Oh yes: Piasecki!

Nice to see there's still life in their compound helicopter design. :)

[SASless]

Am I just an old duffer who has nothing good to say about "new" things or do I see a wee small possibility for FOD ingestion by the tail fan should this concept ever go to war in the desert, forest, or similar terrain?

Perhaps it is just me....as the Osprey is now in Iraq for use in combat operations there.

Fat chance we will see them in Afghanistan I would suggest.

[TwinHueyMan]

Word has it they're using surplus Huey main rotor blades to make the pusher prop. No worries about fod hurting them, plus you get the wop wop sound too!

[international hog driver]

We were doing our recurrent at FSI Deleware and this thing was doing circuits and it is very impressive.

Standard Blackhawk beat with buzzsaw noise deeper than that of the 76.

Very very impressive in flight looks weird with the wings though.

[Ian Corrigible]

99--Appraisal and report of fair market value of highly modified experimental aircraft (YSH-60F (X-49A) Helicopter, Navy Bureau Number 163283 (https://www.fbo.gov/index?s=opportunity&mode=form&tab=core&_cview=0&id=69c2d1ee4c3120976cf73a307e36a293)
Solicitation Number: N0038310QHELO
Agency: Department of the Navy
Office: Naval Supply Systems Command
Location: NAVICP-PHILADELPHIA

Original Synopsis: May 13, 2010
Solicitation Number: N0038310QHELO Notice Type:
Presolicitation Synopsis: Added: May 13, 2010 4:29 pm

NAVICP Philadelphia seeks professional appraisal and report of fair market value of highly modified experimental aircraft (YSH-60F (X-49A) Helicopter, Navy Bureau Number 163283, and associated list of support equipment. Offeror must provide proof of professional certification, National Aircraft Appraisers Association or comparable industry standard, prior to award, and have the capability of evaluating a highly modified experimental aircraft.

I/C
filler...

[Shawn Coyle]

I guess this means the end of the line for this machine - can't see it getting demod'd and returned to service. Sad.
I'd pay $1 for it...