Russian Tractor

[kolibri282]

Just a littel look beyond the rim of the tea cup. This aircraft from Russia will surely come at a price at the upper end of the range but what a nice, clean design.

http://www.i-mash.ru/news/nov_predpr/6535-avtozhir-mai-208-podnimitsja-v-vozdukh-vesnojj.html

The text says that first flight is scheduled this year in spring. I hope they'll make it.

Enjoy,


Juergen

PS: There is an earlier artists impression here: http://www.helicopter.su/press-centr/novosti/161.html

[WHY]

Is this the one that is derived from a fixed wing aircraft ? I wonder about the width of the main gear ?

Tony

[kolibri282]

Tony,

thanks for the hint! In the artists impression link you find this phrase:

модификацией легкого многоцелевого самолета МАИ-223.

which means that the 208 is a modification of the multi purpose aircraft type MAI 223. The kinship between the two can easily be seen here:
http://www.mai.ru/events/news/index.php?ID=7208

and I agree that they should realy make an effort to widen the track for the gyro!

Cheers,


Juergen

[Arnie Madsen]

Very nice. I like the way the cockpit widens at the top. It should provide good visibility.

Do you know if it will be sold as a certified gyroplane ?

That would also be good news.

[kolibri282]

Arnie,

I did not find anything about the process or time schedule for certification but the description gives a
very wide range of missions the aircraft can be used for. Amongst others these are:

- basic and advanced training
- aerial photography
- crop dusting
- general aviation

For any of these the aircraft would have to be certified and so I take it that it will be for sale one day.

There is a technical description and a three view drawing here:
http://www.oskbes.ru/208.html

Cheers,

Juergen

[Alan_Cheatham]

.................................................. .....................

[RotoPlane]

I think this tractor is a neat design. I really like the cabin layout and the rotorhead is interesting. It may even have a collective pitch control.....for jump takeoffs? You find some neat stuff Juergen!

[kolibri282]

Yes, Ed, she's one cute little bird, isn't she? I'm affraid she's not designed for jump take off. The technical specification says take off run is from 15m onwards and I also found no hint in the rest of the description (though my Russian is not that great, so perhaps I missed something). The rotor head indeed seems quite special. There seem to be several links and I feel I do not fully understand how it works. What is your opinion regarding the narrow track? If I find more people who agree it's too narrow I might try to write to the company and ask them to comment on that.


Cheers,

Juergen

[mcbirdman]

What I find interesting is the landing gear.

Look at the front rear movement of the shock and rotation at the top of the main strut. That is what I wanted to do..... Like Blackhawk helicopters. Intead of a big scrub with a parallalogram type movement the strut could compress front to rear and maintain alignment. I see the shock strut is forward of the main though and is loaded differently.

Is this what I see on this machine?

[WHY]

Am also a little concerned about how the rotor mast is tied into the top of the craft, looks like very little lateral bracing.

Tony

[RotoPlane]

Juergen - What is your opinion regarding the narrow track? If I find more people who agree it's too narrow I might try to write to the company and ask them to comment on that.

I can't tell if they have made the rotorhead in a way that will give it more authority over the airframe for pitch and roll (like rubber dampening). The gear may be just fine and like James, I like its aft shock rotation. Because the gear legs are longer than they need to be, I have a feeling they plan on adding an external cargo tank for crop dusting and other things. The Russians sure come up with some neat designs…..

[kolibri282]

Am also a little concerned about how the rotor mast is tied into the top of the craft, looks like very little lateral bracing.


Tony,

if you enlgarge the picture Alan posted one can see a pretty substantial strut between the two seats. I think that one could well take care of the lateral bending moment generated by the rotor, in fact the Russians have a reputation of rather following the Allis-Chalmers School of Design....;-)
(If you compare the data of the Il-18 with those of her contemporary, the Saab Scandia, you find that the Il-18 weighs in - empty- at about 25000 lb compared to 20000 lb for the Scandia, consequently the Scandia carried the same number of passengers about 250 miles farther than the Ilyushin)

Cheers,

Juergen

[WHY]

Ahh Soooo

Tony

[kolibri282]

A very interesting feature of the MAI 208 surely is the rotor head. I came across a few close up shots which are from this site:

http://www.reaa.ru/cgi-bin/yabb/YaBB.pl?num=1238961333/all

The description says (as far as I understand) that the blades are sort of self balancing, any idea how that might work anyone?

[karlbamforth]

If you ignore the top links, it appears to be just an underslung head, albeit an unusual design.

The top links appear to be some form of droop stop.

It did get me thinking.
Someone once said that undersling is set for a particular coning angle and that if you increase the coning angle, say in a banked turn then it causes vibration.
Now what if we connect the top links in such a way that as the rotor coning increases the links can vary the undersling. Basically a feedback between coning angle and undersling.

Just the random musings of a tired brain, any thoughts anyone ?

[Arnie Madsen]

I am hoping that someone can help describe how that MAI 208 rotor head functions. It is an interesting layout , and I am sure the designers knew what they were trying to accomplish. Right now I don't grasp it.

Very interesting. Thanks.

Arnie.

edit: Karl , thanks for your info. My mind is tired too. Tomorrow I hope to be enlightened. Thanks

[Bob Gregory]

Russian tractor gyro of forum May 2010.
Tony asked about tread of mains?
Pazmany and Hollmann have recommendations.
Gyro has aft turnover angle of 33 degrees, which means if
tips past 33 degrees will go over.
Ideal by Hollmann is 45 to 50 degrees like the Sportster.

Center Line Thrust of 38 inches with the mains set at 25.6 degrees
to the vertical cg will make it squirrelly.
Ideal is 15 to 17 degrees.

The complex rotor must have devices to prevent flapping,
because the 23.2 degree angle to rudder is vulnerable.
Ideal is 53.2 degrees.

If 550 kg is correct, any one know russian?
The 27.5 rotor is short.

There must be a reason for the short tail wheel.

I do not have an opinion.

[kolibri282]

Bob,


Взлетная масса 550 кг -> (take off weight = 550 kg)

Полезная нагрузка (включая массу экипажа, топлива, спецоборудования и химикатов) 230 кг -> ( (payload including crew mass, fuel, chemical special equipment) = 230 kg)


Center Line Thrust of 38 inches with the mains set at 25.6 degrees
to the vertical cg will make it squirrelly.
Ideal is 15 to 17 degrees.
I think they have to set a larger angle since they are using a torision spring (just a guess from my part). If they'd select a 17 degree angle the initial stiffness of the system would be to high since the lever arm is to short.

Your observations are quite interesting and fun to read (it's a bit like standing at a hospitable bar at some remote airfield and just "talk gyros"..., add the drink of your choice (wodka??) to the scene ;-)

Cheers,


Juergen

[Bob Gregory]

Thanks to Juergen of Duesseldorf, "kolibri282", senior member.


Never trust a fart and never trust a test pilot. Run if you must. USAAF pilot 1945 in stolen german helicopter.
http://www.facebook.com/video/video.php?v=1045738993474

The YO 60 Kellet gyro of 1944. Amazing.
http://www.facebook.com/video/video.php?v=1049197959946

Rotocycle of 1958.
http://www.facebook.com/video/video.php?v=1044702767569

[kolibri282]

Bob,

thanks for this beautiful collection of outstanding aircraft.

- The YO 60 would even today be in a class of her own with her impressive jumpstart
and "land on a dime" capability

- The 282 was probably the best light helo at the time of her first flight and was still
not far behind by the end of the war. Just look how the american pilot flies her
backwards and even hovers hands off for a moment, although she does not have
any stabilizing device.

- The Rotocycle last but not least is every boys dream of one cool way to get to
the next diner, order a milk shake at the bar and then leave, winking an eye to
that blond (brunette, black/red haired ) girl he always wanted to impress....;-)


Great entertainment!


Juergen

PS: I wonder whether all the tractor nuts of forum 24 have noticed these descriptions of some old predecessors:
http://www.rotaryforum.com/forum/showthread.php?t=25861

[Bob Gregory]

Kolibri282, More facts about it.

Leigh found this.

http://www.century-of-flight.net/Aviation%20history/helicopter%20history/Flettner.htm

[kolibri282]

Bob,

thanks for another nice piece of information on one of my favourites (yeah... that avatar isn't purely accidental)

The aircraft proved impressively controllable in flight and was a major improvement over the Focke-Achgelis designs.....Flettner also demonstrated that the little craft could land on a ship, even in heavy seas.

If we go on heralding the virtues of the 282 like this we'd only have to set up a factory for replicas and we'd be rich in no time....;-)


Have a nice weekend!

Juergen


PS: I hope sincerely that someone who has a little bit more money than I have at my disposal will one day build that replica!

[Russ Hobbs]

I really enjoyed the links, amazingly talented engineering, we need give more respect to these pioneers in aviation.

[9aplus]

Some of my pictures done on MAKS2009
http://i730.photobucket.com/albums/ww304/d9aplus/AvitaikaMaiGiro1sm.jpg
http://i730.photobucket.com/albums/ww304/d9aplus/AvitaikaMaiGiro4sm.jpg
http://i730.photobucket.com/albums/ww304/d9aplus/AvitaikaMaiGiro3sm.jpg
http://i730.photobucket.com/albums/ww304/d9aplus/AvitaikaMaiGiro2sm.jpg
http://i730.photobucket.com/albums/ww304/d9aplus/AvitaikaMaiGiro6sm.jpg
:yo:

[kolibri282]

Djani,

great pictures which again reveal some puzzeling details, like: what good is that maze of hydraulic(?) lines on the pilot side and why on earth do they have two tubes from the control handle( what's the correct term for it, is it control yoke?) into the instrument panel.

Very amazing, thanks for the pics!


Juergen

[9aplus]

Juergen

On first question answer is hydraulic brakes, there is also hydraulic brake
on pre-rotator disc too.
On second, no clue but can ask, hope to meet some Mai people in June....

Fly safe....

[RotoPlane]

Thank you Djani for these pictures…..

I think the two control yoke tubes are a simple way to separate the pitch and roll control elements. This also places the center of rotation of the yoke closer your hand movement, unlike a normal single tube arrangement.

The tubes slide through the roll housing with pitch change which moves that center mounted column that pivots at its base, which in turn moves the push/pull tube running aft.

The center of these same tubes force the roll housing to pivot around that bolt about 2.5" above the tubes. The roll bellcrank can be seen in the forth picture.

It appears the pilot in command sits in the left seat because of the hydraulic brakes, but the instruments suggest he sits in the right seat….don't care for that layout.

I find this craft to be a very interesting design.

[Sapientino]

very nice machine!!!!
Jurgen do you understand the haed?
I seems a variable coning angle (a kind of semi articulated rotor)

[WHY]

Would sure like to see this succeed , hope this international monetary crisis doesn't crap all over everything for everybody. This would sure make a nice basic machine, kind of like the gyro version of the Cessna 150. If the price could be made reasonable I think it could be come very popular as long as it does not have any unusual "twitchy" flight or handling characteristics.

Tony

[9aplus]

http://i730.photobucket.com/albums/ww304/d9aplus/autogiri4sm.jpg

I am looking for test flight soon, hope to be able to write report after :plane:

[kolibri282]

Djani - I am looking for(ward to a) test flight soon, hope to be able to write (a) report after(wards) Boy, a first hand flight report would be marvelous, Djani!

Sapientio - Jurgen do you understand the head? No clue. Karls idea of a self adjusting coning angle sounds promising and the russian description says something about self centering but when I drew a kinematic sketch I ended up with an overdeterminate system, which is a no go for any gearing.

Ed - ...the two control yoke tubes are a simple way to separate the pitch and roll control elements
any Bonanza and all the rest of the birds does this with a single tube (of larger diameter), no?

Cheers,

Juergen

PS: I added a bit to your post, Djani. Just tell me to cut it out if you don't like it, honestly!!!!

[WHY]

I'm guessing it's going to require more rudder, possibly twins, because of "P" factor on steep climb out.

Tony

[RotoPlane]

Juergen: any Bonanza and all the rest of the birds does this with a single tube (of larger diameter), no?

Yes….that's what I was referring to with "unlike a normal single tube arrangement". It looks to me that overall the Russian 208 control yoke is somewhat simpler and takes up less space behind the panel than a single tube arrangement. A disadvantage is the required panel cutout for the 208 doesn't look very cool. I would like to see a video of this control assembly moving…..

I really thought Juergen, that you would have the rotorhead workings figured out by now….what's the holdup? ;)