‘Retractable Skidded’ AH-1 Cobra

[Pioneer]

‘Retractable Skidded’ AH-1 Cobra

When Bell first came up with the efficient and versatile Bell AH-1 Cobra combat helicopter design, it originally went one step further by incorporating a retractable skid arrangement. This arrangement featured the skid’s retracting into the narrow fuselage. I think the idea was to minimise drag, to achieve maximum speed.
Was it the US Army that decided against this retractable skid concept or was it Bell?

I personally think that they got it right, using a fixed skid layout because of the potential of added weight of the hydraulics that would have been needed.
More important in my mind is with such a narrow fuselage design as the Cobra, it would have been a very dangerous and risky task for a pilot to put the Cobra safe on the ground if the retraction failed or due to battle damage.

Was a retractable skidded AH-1 Cobra actually built and test flown?
If so does anyone have any pictures or drawings of it?


Regards
Pioneer

 

[Matej]

Skids must be very robust on combat helicopter. If nothing other, than because they must absorb some kinetic energy during emergency landing. Idea of a retractable skids on attack helicopter is useless - what is the counter-value of additional weight, another device with potential failure, less safety.... Plus 10 kmph during max. speed?

I have some pics of the mockup D-255 that is without any gear but I assume, that this is not what you are looking for....

 

[elmayerle]

I really can't see an operational combat helicopter being made with retractible skids as the extra complications for maintenance, reliability, et al. are just too much for the gain (a comparatively small one) in performance. Retractible wheeled gear is a different story since either way it has the energy absorbing function already built in and the retraction system is fairly straight-forward and simple (well, generally; some engineers needlessly complicate everything - a pain for those of us who don't).

 

[Jemiba]

It isn't the photo, I was looking for, but if this isn't a fake, the Cobra prototype
has retractable skids. The photo is from http://www.aircav.com/cobra/ahgal06/ah1g-009.html ,
there's a vast number of other photos, but I stopped browsing, when I found this.

 

[elmayerle]

I'd be willing to wager that evaluation of the prototype led to the abandonment of retractible skids.

 

[Jemiba]

But the idea seems to have been interesting for others, too. Or
should I say : The cockpit section of the Cobra was so attractiv,
that Nord Aviation planned to bolt it to it's N.500 ducted fan VTOL
a/c, to get an attack version ? ;D

 

[overscan (PaulMM)]

I have a picture of the Model 209 prototype in Air International, it has retractable skids and a ventral fin.

 

[Maverick65]

It isn't the photo, I was looking for, but if this isn't a fake, the Cobra prototype
has retractable skids. The photo is from http://www.aircav.com/cobra/ahgal06/ah1g-009.html ,
there's a vast number of other photos, but I stopped browsing, when I found this.

Hi Guys,

My first post here, the site is very cool, heaps of informative threads. Regarding the Cobra, the photo looks like it's a photoshop job, the original prototype flew without skids, not retractable, just removed, altho this isn't the case with this pic as the aircraft has the TOW system from an AH-1Q and the tribarrel cannon (albeit shortened) from an AH-1S. There is a bit of pixel damage around the cockpit area in addition.

Just a thought,

Maverick

 

[Cobrapilot]

The original Prototype AH-1 Cobra did have retractible skids. It registered as N209J and was on display for many years at the Patton Museum of Armor and Cavalry at Ft. Knox, KY. It is my understanding it has recently been moved to Ft. Rucker, AL for display at the Army Aviation Museum. The weight of the retraction system as well as maintenance and reliability issues outweighed the limited reduction in drag it offered. Fixed skid offer the added benefit that pilots can't forget to extend them prior to landing and therefore don't require warning lights and warning tones and remind us ;D

 

[F-14D]

The original Prototype AH-1 Cobra did have retractible skids. It registered as N209J and was on display for many years at the Patton Museum of Armor and Cavalry at Ft. Knox, KY. It is my understanding it has recently been moved to Ft. Rucker, AL for display at the Army Aviation Museum. The weight of the retraction system as well as maintenance and reliability issues outweighed the limited reduction in drag it offered. Fixed skid offer the added benefit that pilots can't forget to extend them prior to landing and therefore don't require warning lights and warning tones and remind us ;D

Exactly so. In fact, fairly early in the test program Bell just locked the skids down on the prototype for exactly the reasons mentioned.

 

[Nico]

Sorry for the delay folks!
The pic you referred is probably the one I enclose: I remeber have seen several shot of the same flight and I'm pretty sure wasn't a fake


Nico

 

[Jemiba]

In L + K 1965/1 a front view from the AH-1 prototype was shown, which
despite the quite bad quality shows at least the shape of struts.

 

[luedo34]

Two more pics of the N209J, one on the ground, one in flight. The second picture shows a very early N209J with the ventral fin, which was later removed because it proved to be unneccessary. It was intended to improve stability during autorotation.

 

[Pioneer]

Nico, Jemiba and Luedo34

Thanks heaps for your time and fantastic effort in finding these very interesting picks!!!!

Keep them coming if you find them!!!!!


Regards
Pioneer

 

[Nick]

There's a very good pic of the skid and where it would have retracted to over on ARC. Photos taken at Fort Rucker. I found this via the RAH-66 Comanche thread here!

http://s362974870.onlinehome.us/forums/air/index.php?showtopic=137962&hl

 

[Pioneer]

Wow thanks Nick
An interesting find and a privilege you must have experienced!! Very envious

How about the comfortable seats in the N209J!!
Also very interesting info on the manually deployable sub-wing landing gear back up arrangement.

As a side note - great pics of the Sioux Scout! First time I've seen the rocket arrangement - thanks again


Regards
Pioneer

 

[luedo34]

A nice shot of the N209J ...isn´t she beautiful?

 

[luedo34]

Apparently Bell considered different types of landing gear...
One of the possible variants was this type with folding outer wings.

 

[Pioneer]

Outstanding find luedo34!!!!!!!!

Thanks very much!

How the mystery unwinds ;D

Please keep them coming!!!

Regards
Pioneer

 

[dansew]

Skids must be very robust on combat helicopter. If nothing other, than because they must absorb some kinetic energy during emergency landing. Idea of a retractable skids on attack helicopter is useless - what is the counter-value of additional weight, another device with potential failure, less safety.... Plus 10 kmph during max. speed?

I have some pics of the mockup D-255 that is without any gear but I assume, that this is not what you are looking for....

Hi, everyone, new here, first post.

I worked at Bell Helicopter from 1953 to 1973, I was one of the members of the engineering experimental project team which produced the first Cobra, N209J.

The landing gear was retractable, hydraulic, with clamb shell doors.

The reason for this was sales appeal, same reason the outside had flush rivets.

They wanted the aircraft to "look like it was going 100 MPH while hovering"

The project was fully funded by Bell, and took one year from 3 view drawing to "roll out".

My duties were design of pilot and gunner stations, and liaison between engineering and manufacturing assembly.

 

[Stargazer]

Hi, everyone, new here, first post.

I worked at Bell Helicopter from 1953 to 1973, I was one of the members of the engineering experimental project team which produced the first Cobra, N209J.
My duties were design of pilot and gunner stations, and liaison between engineering and manufacturing assembly.

Welcome aboard, dansew! It is great to have you here and to hear you share your experience of how that most beautiful machine, the N209J, was created. Hope you'll be writing some more!!

 

[Pioneer]

Welcome aboard dansew!!
Thanks for your productive (and I must say envious) experience and contribution to the building of the first true production and effective helicopter gunship!!
I, and I am sure my colleagues, are looking forward to what you might be able to bring to the forum!


Regards & once again welcome
Pioneer

 

[dansew]

Thanks a lot for the very warm welcome, looking forward to sharing with, and getting to know you all.

There's a kindred spirit among those with aviation blood in their veins .

 

[yasotay]

Dansew - welcome aboard. It is great having someone with your experiances here with our merry little band!

By the way a very personal "Thank You" for the sweetest ride I had in all my years flying helicopters. Sure do miss the Snake.

 

[dansew]

Dansew - welcome aboard. It is great having someone with your experiances here with our merry little band!

By the way a very personal "Thank You" for the sweetest ride I had in all my years flying helicopters. Sure do miss the Snake.

Thank you so much, makes an old man's heart warm. ;D, although my work on the snake was over after N209J roll out.

 

[Stargazer]

Dansew, I suppose you must have been involved in some of the various stages that preceded the N209J: D-245, D-255, D-262 Iroquois Warrior, D-280... Maybe you'll be telling us some of that? It sure would be interesting.

 

[Pioneer]

Dansew, I suppose you must have been involved in some of the various stages that preceded the N209J: D-245, D-255, D-262 Iroquois Warrior, D-280... Maybe you'll be telling us some of that? It sure would be interesting.

I second that!!

Regards
Pioneer

 

[luedo34]

Oh, yes Dan, that would be great!
Alex

 

[dansew]

I am sorry, guys, I just didn't work on any of those, if you get into pictures, or discussion of them, it might spark a rememberance, but as far as day to day work, they just were not anything I was assigned to.

 

[dansew]

The questions about the D-245, 255,252,and D-280. The reason I didn't know about them, is that it was a "Bell Confidential" project, and they built the Mock-up in a restricted area, about 400 yards from I was working, and I never knew about it,

Bell tried to sell the Army on the above ideas, and they were not interested, so the powers that be at Bell decided to build the N209J, from three view drawing to roll out it took 5 months and 28 days, I know we sure worked a lot of overtime. I think I told leudo34 that it took 12 months.

The Army office at Bell never knew it was being built, this kinda explains why the flush rivets and retractable landing gear, ....... sales appeal..

That picture of the D-255 mock up, is one that I had never seen until today, guess I lived a sheltered life at Bell.

And this explains why the original 3 view shown at that website did not look like the N209J, because they started from almost scratch with the Cobra. A new 3 view called Model 209, dated 3-16-65

 

[luedo34]

Well, just a few pics of the mentioned projects.
luedo34



(All from Bell via the Helicopter Museum Bückeburg, Germany)

 

[Rickshaw]

Are those SS11s that the mockup is shown with on the stub wings?

 

[luedo34]

Yes, I do think those are SS-11. The description on the backside of the photograph said so, at least.
By the way, a very stupid question: How can I convert lb into litre?
The problem is the following: The Bell KingCobra is said to have carried 2300 lb of JP 4 fuel. But how can I convert that into litre?
As I understand the density ( and therefore the mass) of JP 4 varies depending on temperature...
??? ?

 

[overscan (PaulMM)]

Indeed - there are standard conversions.


Aviation fuel is generally given as 0.81Kg/L.






http://www.wbdg.org/ccb/FEDMIL/dtl5624u.pdf


lists JP4 as:



Density, at 15°C
kg/L, min (API max): 0.751 (57.0)
kg/L, max (API min): 0.802 (45.0)

 

[luedo34]

Thank you! That helps a lot.

 

[fightingirish]

Sobchak blog - I Monopodi del Cobra


Emergency skids for the Bell Cobra N209J.

 

[Pioneer]

Sobchak blog - I Monopodi del Cobra


Emergency skids for the Bell Cobra N209J.

Nice and interesting find Fightingirish!!
Regards
Pioneer

 

[ksimmelink]

‘Retractable Skidded’ AH-1 Cobra

When Bell first came up with the efficient and versatile Bell AH-1 Cobra combat helicopter design, it originally went one step further by incorporating a retractable skid arrangement. This arrangement featured the skid’s retracting into the narrow fuselage. I think the idea was to minimise drag, to achieve maximum speed.
Was it the US Army that decided against this retractable skid concept or was it Bell?

I personally think that they got it right, using a fixed skid layout because of the potential of added weight of the hydraulics that would have been needed.
More important in my mind is with such a narrow fuselage design as the Cobra, it would have been a very dangerous and risky task for a pilot to put the Cobra safe on the ground if the retraction failed or due to battle damage.

Was a retractable skidded AH-1 Cobra actually built and test flown?
If so does anyone have any pictures or drawings of it?


Regards
Pioneer

The only Cobra to come out with retractable skids was the Bell Model D209 which was inteded to get interest from the Army for a production version. When the two prototypes were built they incorporated the following changes over the D209 - "the fittings for the weapons turret housing were enlarged to accomodate the Emerson Electric TAT-102A turret; the stub wings were made larger so as to allow the carriage of ordinance pylons; the ventral fin was removed; and fixed-tube landing skids replaced the retractable ones." Other wise it went into production pretty much as the model D209 had been designed. This allowed for a rather speedy introduction into service. (The Quote is from Jonathan Bernstein's book US Army AH-1 Cobra Units in Viet Nam) The book does not say whose decision it was to remove the retractable skids, but I am sure for the sake of maintenance in the field, solid skids are far more desirable, while not impacting the performane a whole lot. I would think the trade off between drag of the fixed skids and the weight and reliability of retractable skids would be in favor of the fixed skids. Fixed skids really aren't very suseptable to battle damage, but a lucky shot on the retractable skids would not only render the skids inoperable (or one side) but would amount to pretty much a total write off when the helicopter lands with either an asymmetrical skid deployment or none at all.

 

[AeroFranz]

Nice article on Air and space mag.

Birth of the Cobra

Mike Folse proved that a helicopter could fly and shoot at the same time.

www.airspacemag.com

Reason for deleting retracts given as fear that in south east asia operations mud would get into wells.
I noticed the article also says the prototype had an "umbrella dive brake". Anyone has a picture of this?

 

[Basil]

The excellent book "Cobra! The Attack Helicopter" by Mike Verier covers the whole development and all versions of the Cobra in detail including several different ideas for a retractable undercarriage. Very recommended read.