If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#27
|
|||
|
|||
I shall look forward to seeing how it all turns out.
Good luck, & keep us posted. AC On Mon, 31 May 2004 18:31:59 +0000, Richard Lamb wrote: I already have four compression fractured vertebra, so this is not just an academic exercise. (From my fun summer vacation in Viet Nam) Sitting on the main spar like that, there just isn't a lot of 'crumple space' between the warm pink bottom and the cold hard ground. So any landing that wipes out the gear could be pretty serious. BTW, that is one of the things we are looking at very carefully. In the event of a gear failure, where will all the big pieces go, and will they go thru anything soft and squishy on the way out(?). Beyond pilot comfort, I think this is a good place for a layer of Temperfoam (seat bottom). It's heavy stuff for its size, but Temperfoam will absorb quite a bit of energy in an impact situation. Anything that can slow down the energy transfer - even a few more milliseconds - will reduce back injuries significantly. It shouldn't take more than six pounds for the foam. I never heard of it before - but it looks just the ticket. After that, the most serious threat is smacking the head on something hard or pointy. This cockpit is close enough that a good shoulder harness should be mandatory. But that brings up the age old question of where to attach the harness so that it can actually take the impact load without failing the attach structure. I'm guessing 30 G's (eyeballs forward) for 50 milliseconds? Next, I worry about fires. Been there, singed holes in my T shirt. A big gas tank in front of the panel is the simplest lightest way to store gas, but it is also vulnerable in an accident. Cracks in the tank, broken out fittings, or fuel line torn loose? None of these are pleasant options when the gas is sitting in your lap. However, on this plane, there is no way to put 20 gallons (120 lbs) in a nose tank and still be within the CG range. For that one reason we have decided to put the tanks in the wings. Ok, so now, do we still want to have a header tank at the firewall (for a gravity feed), or feed directly from the wing tanks (gotta have fuel pumps anyway!)? Lastly, reducing the amount of commanded energy at touch down is probably the best way to improve survivability. Get the stall speed down as much as practical. My first wing estimates indicated stall speed about 65 mph. (I had some rather impressive fantasies about cruise speed) That's just way to very dam fast (for this old fart, any way). Another 12 sq ft of area, and a slightly different airfoil got it down to around 52 mph. Only way to improve on that is to add flaps. Flaps could cost as much as eight or ten pounds... But getting the landing speed down to 45 MPH or so? Hard call there. (compromise) I'm afraid a ballistic parachute is way over weight budget. It certainly won't help you get over the trees at the end of the runway... I loooked up BRS systems - 34lb lol. Richard Lamb http://home.earthlink.net/~n6228l/l-one.htm |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Homebuilt Aircraft Frequently Asked Questions (FAQ) | Ron Wanttaja | Home Built | 0 | April 5th 04 03:04 PM |
Homebuilt Aircraft Frequently Asked Questions (FAQ) | Ron Wanttaja | Home Built | 2 | February 2nd 04 11:41 PM |
Homebuilt Aircraft Frequently Asked Questions (FAQ) | Ron Wanttaja | Home Built | 1 | January 2nd 04 09:02 PM |
Homebuilt Aircraft Frequently Asked Questions (FAQ) | Ron Wanttaja | Home Built | 0 | October 2nd 03 03:07 AM |
Homebuilt Aircraft Frequently-Asked Questions (FAQ) | Ron Wanttaja | Home Built | 0 | July 4th 03 04:50 PM |