Gazelle Pit

I'm starting on a new project.

I have just sold my A-10 pit and I'm starting on a Gazelle, this time using an Oculus Rift.

I'm going to build the controls from scratch and I want them to correspond to the virtual model.

I need some information please on the feel of helo controls in general and the Gazelle in particular.

Does the cyclic have a centre position (like a fixed wing joystick or does it flop to one side as you let it go?

Is there any force feedback from the rotors? Does it change with the pitch?

More questions to come I'm sure.

Thanks

Matt

In real helicopter you have got to find the so-called neutral cyclic position. If we were turned off magnetic brake, stick would "fell" on one or the other side. There is no center position.

There no any force feedback from the rotor on cyclic or collective stick. FF can be felt only when we turn off "SERVO" switch on the collective stick, and this force is quite strong. For P-C Gazelle I don't know. I haven't bought yet. :joystick::)

OK Thanks,

So collective is servo assisted. How much force is required to move it with the servo on (easy with one finger?) I guess it stays put when you let go?

Well ... it depends from helicopter to helicopter, but in principle should stand in the position in which you left it. You can't move collective with one finger, you have to make more power, and never, but never take your hand off from the collective stick. Cyclic, on the other hand can be moved even with the little finger.

OK that's very helpful, thanks. I'm going to put adjustable dampers (motorcycle steering dampers?) on all of the axes to get the feel right.

I would definitely recommend you to go to some aeronautical museums, exhibitions or private helicopter companies and meet with Gazelle.

(Hurstbourne Tarrant in Hampshire, Stapleford airfield ...)

@xray20 Any progress on this? I too am working on a Gazelle pit, also for VR =)

@Trip,

I'v had no luck getting a flight in a Gazelle or even a look at one or talk to a pilot.

I spoke to MW Helicopters at Stapleford and they didn't know of anyone with an Air Operators Certificate for a Gazelle - necessary to take (paying) passenger.

I subsequently learned that the CAA have withdrawn permit to fly with fare paying passengers on ex-military aircraft , so I need to find someone who will let me fly as a 'navigator' or 'ground handler'.

Anyhow, I have continued work on the pit. I'm using ACE Fabreeka rotary dampers on all of the axes and these provide some good back pressure without loss of sensitivity. I can fly with my hand resting on my leg and very small movements. Much better than the HOTAS stick I was using before.

I'm using a Bodnar controller and hall effect sensors and they are very accurate. I finished the collective yesterday and it works very well.

I have now started on the rudder pedals. I'll post pictures when I'm ready to install.

@Trip,

I'v had no luck getting a flight in a Gazelle or even a look at one or talk to a pilot.

I spoke to MW Helicopters at Stapleford and they didn't know of anyone with an Air Operators Certificate for a Gazelle - necessary to take (paying) passenger.

 

I subsequently learned that the CAA have withdrawn permit to fly with fare paying passengers on ex-military aircraft , so I need to find someone who will let me fly as a 'navigator' or 'ground handler'.

 

Anyhow, I have continued work on the pit. I'm using ACE Fabreeka rotary dampers on all of the axes and these provide some good back pressure without loss of sensitivity. I can fly with my hand resting on my leg and very small movements. Much better than the HOTAS stick I was using before.

I'm using a Bodnar controller and hall effect sensors and they are very accurate. I finished the collective yesterday and it works very well.

 

I have now started on the rudder pedals. I'll post pictures when I'm ready to install.

But if you are in London you should be able to attend the event I learned about a few days ago! I bet you could get hooked up for a ride there too if you explain you are building a sim cockpit of a Gazelle.

I desperately want to go to this event in less than two weeks but for me it is a VERY long swim! https://www.armyflying.com/events/all-events/gazelle-commemorative-50th-fly-in/

PS- Based on your picture I think you clipped through your seat so it needs some collision geometry, and you'd better see a doctor quick about the missing textures on your face!

I don't know how much budget do you have, but I suggest to you look some military waste (scrap yard) and look to see, if there Gazelles cabin which could be purchased. What do you think about that?

P.S. For your flight experience try to ask Google Gazelle panoramic flights

@Trip

Great Spot! Its less than two hours away. I have purchased my ticket. Thanks.

PS I really do look like that:(

@kobac

I want to avoid going down the full cockpit thing again (I did it with an A-10C cockpit) - no need with a VR headset, BUT - I think the flight controls must be where the VR says they are and they must feel right.

I will feed back any info I get from the fly-in.

@Xray20 Lucky bastard! I'm really glad my finding out about that event was useful to someone as it was just a tease for me. =(

You can return the favor by supplying me with an insane number of pictures and if you manage to get a ride in one as much info as you can give on your impressions. Remember I'm tuning a motion sim to make it feel as much like a Gazelle as possible!

I wish I could send you with an accelerometer in your pocket and a video recording to go with the data. :lol:

You can get an accelerometer app for smart phones I have gMeter for the iPhone.

I know it's not in the same class but given the power ratting I was very impressed with the capabilities of the Robinson R44 Cadet I did a trial flight in. The iinstructor also flew civilian version of the Gazelle so I asked questions.

As for stick feel it's almost nothing just a bit of resistance in the cyclic. I know I've been banging on about it here but.

https://forums.eagle.ru/showthread.php?t=185036

xray20

I'm also building a heli pit and I'm very interested in your collective setup looks very good.

Would you mind sharing some details??

@Xray20 definitely add a hydraulic steering damper for motorcycle (~$25 USD on ebay) to your collective, it gives it a fantastic feel!

@trip

If I get a ride, I'll definitely be trying to record every aspect, x,y,z acceleration too!

@fragbum

The collective is scratch built as is everything else.

I use 30mm Bosch Rexroth for the frame

http://www.aluminium-profile.co.uk/acatalog/Aluminium_Profile.html

its infinitely adjustable so I can get everything in the right position. With the VR I want to be able to reach down and have a real object exactly where the VR says it should be.

The sensors are TT ELECTRONICS 6127V1A180L.5 Hall Effect Sensor, Position, 180° from Farnell which interfaces perfectly with the Bodnar BU0836X 12-Bit Joystick Board.

Damping of the controls is essential, so I'm using the ACE FDT47 rotary damper

http://www.acecontrols.co.uk/uk/products/motion-control/rotary-dampers/fdt/fdt/fdt-47.html

These are much easier to implement than strut dampers because I don't have to worry about the action length and the effect of distance from the axis. If I want more torque, I just stack them on the shaft. The collective feels like lifting about 2kg.(very difficult to describe torque reaction in words). The cyclic has one damper for each axis. For the rudder I'll use two. The dampers are about £20 each.

@XRAY20

Very good, the Logitech has a very similar style dust cap to the FDT-xx style. Although for the Logitech 3D it would be nice to have a little more force. The kicker here is when you move the position of the cyclic it kinda melts into the new position. The gotcha for me here was to be sure of the amount of movement and the direction, hence next time I go up I want to do a lot of hovering. :thumbup:

Collective may be okay, it was fairly light but because the R44 uses a correlator /governor to set power output from the motor you need to be mindful not to override that aspect of control by twisting the throttle or restricting the throttle when adjusting the cyclic position. So it felt light but not light like the cyclic pretty much stayed where you put it using a kinda loose 3 or 4 finger hold, agree difficult to define.

That likely isn't the case for governed turbines, I'm yet to work that out. :helpsmilie:

I Like the aluminium extrusion, I'm building my prototype using wall framing timber stud (35*70mm pine) and using metal brackets and screws to glue it together, the next one I will use TIG glue. :)

I looked at the Extreme 3D when I tore it down and the buttons and cyclic, and other controls can be extended fairly easily from the existing wiring harness and used as a low cost basic SIM I/F. But a better I/F and encoder(s) sounds great. :thumbup:

Cheers

Robert

Those look fantastic! What did you use on the opposite side as a bearing or whatever for the other end of the shaft? I'd really like to know all the components you used, as this looks like an excellent rig that I'd like to copy for my collective. Just make sure you treat me like a dummy, don't assume I know anything, I probably don't!

 

Damping of the controls is essential, so I'm using the ACE FDT47 rotary damper

http://www.acecontrols.co.uk/uk/products/motion-control/rotary-dampers/fdt/fdt/fdt-47.html

 

These are much easier to implement than strut dampers because I don't have to worry about the action length and the effect of distance from the axis. If I want more torque, I just stack them on the shaft. The collective feels like lifting about 2kg.(very difficult to describe torque reaction in words). The cyclic has one damper for each axis. For the rudder I'll use two. The dampers are about £20 each.

@trip

I'm using AL1218-12 Oil Filled Bronze Flanged Bush 12x18x12mm

http://simplybearings.co.uk/shop/p120736/AL1218-12-Oil-Filled-Bronze-Flanged-Bush-12x18x12mm/product_info.html

as the bearings on each side - mostly because they are easy to work with. These are fixed into 3mm ally sheet for the two quadrant sides using Loctite 603

12mm ground steel rod is used for the rotating shaft which is locked to the collective lever with a grub screw.

I have 2:1 gearing on the end of the shaft to the Hall effect sensor to get maximum resolution. The full travel of the collective gives me nearly min-max rotation on the sensor.

The fluid dampers are fitted to the shaft with 8mm square section steel rod which is turned to round at the end so it can be fitted into a drilled hole in the end of the 12mm rod with Loctite. I have removed the backlash in the dampers with 0.2mm steel shim pushed into the gap. When everything is finished, I'll Loctite these into place. If it turns out that the collective returns to minimum when you let go (at the moment it stays put) I'll put a return spring on it.

The rotating part is a machined steel block which is threaded M8 to take the collective handle. This has 12mm shim washers against the bearings for a good fit.

The handgrip is a piece of 50mm brass tube. The switches will be fitted into a small component case which is fitted to the end of the collective lever.

Matt

I have 2:1 gearing on the end of the shaft to the Hall effect sensor to get maximum resolution. The full travel of the collective gives me nearly min-max rotation on the sensor.

If use TT 6127V1A with 50 or 90 degrees instead the 180 version avoid this reduction?

Fantastic Matt, thanks for all the detail! I will be making use of some of this info to improve my collective.

@ Sokol1_br

Thanks. I didn't know reduced angle sensors existed. I just checked the Farnell website and found they do at least six variants.

No problem, I had the gears and it makes a good way of isolating the sensor from mechanical strain. I have just finished the rudder pedals. I put 3:1 gearing on them. Pictures soon.

for reference see Farnell link

http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryName=All&selectedCategoryId=&gs=true&st=6127V1A

First try-out of the rudder pedals. I'm fairly pleased with how they have gone together. Much better than the Saitek Pros I was using before. It's so much easier flying now the controls are not springing back to the centre position.

The rudder is geared to the (180 degree) sensor at 3:1. There are rotary dampers on each pedal.

I miscalculated how strong and heavy legs are compared to arms so construction in parts is a little lightweight and the pedals are a bit springy. I will double the thickness of the pedal arm if its a problem.

Interesting how I use the rudder now, both feet up on the pedals, controlling with the balls of the feet when manoeuvring and heels on the floor plate controlling with the toes in level flight.

Next step; Thrustmaster HOTAS to weapons control.

Beautiful craftmanship xray20. Really like what you have build on a very sturdy platform :thumbup: Definitely a source of inspiration. Looking forward to seeing more great pictures. Thanks for sharing

Cheers

Hans

Very nice indeed.

Thanks Hans.

@trip

Hi Trip, I have been looking at your motion sim and thinking it would be fun to build one.

Two questions to start:

How do you export the XYZ data from DCS? (export.lua?)

How do you transform the XYZ data into positional data for the platform?

I can't find any motion platform group on the DCS forum - is there one elsewhere?

Cheers

Matt