Cockpit size

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HeliDev

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Im just working some dimensions for my tandem rotorcraft.
I have been basing my size on the Vans RV 4.
Just wondering how others find this for size. Ive been making the cockpit on the larger size, but for drag reasons I want to reduce it a little. I dont know of anyone with a RV, so Im hoping for a little input here.
Im allowing 47.5" length, 42" tall, and 28" wide. (per person)
 

orion

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That sounds pretty comfortable. As a suggestion, take a tape measure to your car - if you're comfortable there then a cockpit layout with those dimensions should work well too.

I'm 6'4" and about 235 pounds (if I inhale a bit of Helium). I find that most homebuilt aircraft are a shoehorn and a gallon of goose grease fit. Most are designed to the 1930's spec of a 5'10", 170 pound pilot. Also, simce most homebuilts are trying to get as much performance as they can, designing a small airplane allows them to squeeze as much speed per seat configuration, without going to larger engines.

The RV-4 may be tight for a wider variety of occupants, especially in the back. I know a few that have been modified for larger occupants but the standard configuration is a bit snug for me. I also am a firm believer of not having the aft passeger straddle the front seat.
 

HeliDev

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Those were my thoughts.
One thing that really ticks me off in the 22 is the lack of space. Im the typical 5'10, 170lbs, and I find it cramped.
If it doesnt effect the CG to much I plan on using those dimensions for both pilot and pax, so the girlfriend doesnt complain to much. However I would like to be able to fit people like your self in with reasonable comfort. What do you nprmally use, if you dont mind me asking.
 

orion

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Actually, the dimensions I use tend to vary from airplane to airplane, depending on the airplane configuration and the wishes of the customer. In general though, I have a pilot figure I got many years ago from a relatively well known configurator (Walt Mooney) I worked with at General Dynamics. I then scaled this figure to a 78" height (including a standard military style helmet and face shield), which gives me a net figure height of just about 6' 4". The figure includes standard issue flight gear so using the resulting dimensions virtually guarantees that any cockpit designed with those requirements will fit just about anyone else comfortably.

A couple of things to keep in mind though. Despite a lot of talk about reclined seating (glider style), the fact is that for most people the most comfortable seating attitude is relatively vertical. I would say that for any normal layout you probably want to use a seat back angle of about 20 deg., certainly no more than 30 deg. If you wish you can add more as an option but I wouldn't depend on too much recline in order to try to cut down the cockpit height.

Also, make sure that the occupant's butt is several inches higher than the figure's heels on the floor. I would say four to six inches at a minimum. Sitting with your but any closer to the floor does tend to get uncomfortable after a while.

Using this as a guideline, and assuming that you don't want to straddle the front seat, should pretty much give you the length you'll need, after you add in the seat widths and any cargo space you might need. Don't be surprised if this comes up with a relatively long space.

Widthwise I think any number over 44" wide (internal dimension) for a side-by-side configuration will work fine. The 28" width you mention should be great for the tandem. Make sure however to provide support for the occupants - you don't want them getting thrown about in turbulence or wind shear.
 

HeliDev

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Thanx orion.
Yeh its very tempting to go for big layback on the seats, makes it look fast on the ground :)
But especially for VTOL or STOL, I feel that you need to be sitting up more so you can spot you landing area better, 20deg was what I was working on. I hate the seats in the 22 though, vertical is not comfortable, after an hour Im looking for a chiropracter.

Actuall the support for the occupants is giving me a few headaches right now.
The Apachie helicopter uses 2 aluminium beams under the occupants to support the cabin stucture. The neat thing is that in the event of a heavy landing, if the gear breaks, the apachie will slide on these so the nose doesnt dig in.
While mine wont be getting shot at, (atleast I hope not), I like the concept and would like to incorporate it. But his means using an internal structure, which adds weight.
Im thinking now about using a chassis typr set up with a composite fairing, seems to offer the best compromise. Gives me tha advantage of being able to add roll bars also.
 

Othman

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Remember that with a helicopter you need to make sure you will have enough room on the side of your seat for a collective stick (if you plan on using traditional heli controls). You want to make sure that there are no obstructions in that area.

Fixed wing aircraft seats can be pretty squeezed together, and since you're using the RV-4 as a reference, you may want to double check the width.
 

2Guns

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Re: Cockpit sizehttps://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=r

Im just working some dimensions for my tandem rotorcraft.
I have been basing my size on the Vans RV 4.
Just wondering how others find this for size. Ive been making the cockpit on the larger size, but for drag reasons I want to reduce it a little. I dont know of anyone with a RV, so Im hoping for a little input here.
Im allowing 47.5" length, 42" tall, and 28" wide. (per person)
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CCAQFjAAahUKEwjslPavmZHJAhUB_R4KHV38CzQ&url=http://www.wanttaja.com/avlinks/cockpit.htm&usg=AFQjCNE3mAp0yjhHGxKOGD7M5aCJlposGg Try this link for size of cockpits.
 

cluttonfred

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LOL, I hope you both realize that 2Guns was responding to a thread last updated in 2004! That said, I believe that there was a cockpit dimensions/suggested ergonomics section with illustrations in Design for Flying by David B. Thurston.
 

Birdman100

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dimensions in this thread are irrelevant today, since at that time people were two times skinnier that today. In 2004, at my 19 I thought i will be bilionare so far :gig:
 

SVSUSteve

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I will point out that while the lateral dimensions are accurate, in an average homebuilt, the recline angle Bingelis suggests would likely increase the rate of spinal injury and potentially serious or fatal chest injuries due to deceleration along the long axis of the body. Also, without a crotch strap (five or six point harness, which isn't a bad idea. HINT HINT) you're likely to do what's called 'submarining' and basically slide out under the restraints which will also drastically increase the risks of injuries.

A lot of his suggestions are kind of quaint and harken back to the days of rudimentary aircraft but that one is just misguided.
 

BJC

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I will point out that while the lateral dimensions are accurate, in an average homebuilt, the recline angle Bingelis suggests would likely increase the rate of spinal injury and potentially serious or fatal chest injuries due to deceleration along the long axis of the body. Also, without a crotch strap (five or six point harness, which isn't a bad idea. HINT HINT) you're likely to do what's called 'submarining' and basically slide out under the restraints which will also drastically increase the risks of injuries.

A lot of his suggestions are kind of quaint and harken back to the days of rudimentary aircraft but that one is just misguided.
The drawing shows that the pilot's knees are low relative to his hips. If the reclined seat has the knees raised, a tight lap belt will prevent submarining. A crotch strap is great for holding the lap belt down, and I encourage the use of one.

I've experienced that sudden stop in an airplane with a seat back slope of about 45 degrees. A good, tight lap belt, plus just snug shoulder straps left me (literally) black and blue under the straps, but no back issues. Now if you want to talk spine compression, lets talk football back in the days when coaches taught leading with the helmet. I've seen some scary things there.


BJC
 

Pops

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My JMR Special cockpit size is 43" length-- 41" tall -- 27" hips and shoulders. Seat can be moved back 2" for 45" length if needed.

Dan
 

plncraze

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The JMR is supposed to carry someone nearly six and a half feet tall. There are not many planes which can do that. I know because I have tried.
 

Pops

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The JMR is supposed to carry someone nearly six and a half feet tall. There are not many planes which can do that. I know because I have tried.
I have 2 large grandsons about that size. I am 6'x 225 lbs and will need some cushions under and behind me.

Dan
 

SVSUSteve

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f the reclined seat has the knees raised, a tight lap belt will prevent submarining.
Even in that position, you will still partially submarine with anything but absolutely perfect positioning on the belts on the iliac crest (the bones that form the front of the his above the hip joint). That's why it's not uncommon to find marks on the mid to upper abdomen from the lap belt in cases where the victim had their seat reclined. It's a great way to vastly increase your risk of solid visceral injury (liver and spleen) as well as the risk of injury to aorta and inferior vena cava if the loading is primarily upper or mid-abdomen respectively.

It's one reason why some car seats actually have a small airbag under the front edge of the seat to push the thighs up and help keep the occupant properly restrained
 
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SVSUSteve

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BJC said:
I've experienced that sudden stop in an airplane with a seat back slope of about 45 degrees. A good, tight lap belt, plus just snug shoulder straps left me (literally) black and blue under the straps, but no back issues.
I imagine you probably didn't get to the level of deceleration we're talking about. It's the "skin vs tin" level.

Agreed on the football issue. Between concussions and spinal injuries, it's amazing how little though has been given to player safety until recently.
 

MaverickSawyer

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Won't argue with a 5-point rig. 4-point on a Stearman is a little spooky when the guy in command decides to hotdog it a little... :ponder:

That said, small cockpits are NOT a good thing for me. 6'2", broad shouldered, etc. Usual gripes over small cabins... not enough shoulder space, I'm folded up on takeoff and landing so I'm not on the pedals or yoke, no headroom to speak of. For my design I'm starting to eyeball figures for, I was looking at essentially a slightly narrower (shave 3-4 inches off the sides) version of a Mazda or Toyota light pickup cab. I've always been comfortable in those, and getting dimensions off those is easy.
 

SVSUSteve

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Pops said:
My JMR Special cockpit size is 43" length-- 41" tall -- 27" hips and shoulders
The seats for the Praetorian are designed at 23 or 24" wide (I don't have the design file open in front of me). From the seat to the firewall is five feet. It wasn't designed for 95th percentile men but rather to give someone my size (5'9" and 180 lbs) plenty of room for the foot pan to crumple in a crash. It also allows for more area behind the instrument panel to install things.
 
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