Raptor Composite Aircraft

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Rik-

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Sep 13, 2019
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370
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San Rafael, California
I concur with your list. We have similar thinking. I even go a bit further, so we thought of:
  • a safety cell sustaining more than 26G
They thought this something in the boat racing too. Turns out all your doing is trying to make a crush proof coffin as no one can survive the rating and the weight of building such a structure is tremendous
 

Scheny

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Feb 26, 2019
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201
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Vienna, Austria
They thought this something in the boat racing too. Turns out all your doing is trying to make a crush proof coffin as no one can survive the rating and the weight of building such a structure is tremendous
Only half right. The safety cell can never be too strong, as it depends on the exposure time what someone can survive. A short impulse of 40G is totally survivable, but can already lead to collapse of a standard cell. The second part is the energy absorption. As deceleration is about bleeding speed over time, you can cut deceleration into half by doubling the crumple zone.

The complete nose and front gear is designed in a way to absorb lots of energy at about 15G deceleration. In addition, the front bulkhead incorporates technology to minimize the remaining shock.
Could you explain this better? Thx.
As most customers for a single seat jet are not used to jets, it is essential to minimize their workload. One of the key factors is to keep speeds. Jets have the problem of suffering from low drag on the one side and having a high minimum thrust on the other. Our jet has almost no sink rate at idle and would accelerate to 150-180kt on a standard glidepath (with turbine at idle). To avoid this, it will incorporate spoilers, which are activated with the thrust lever. Move to the front, increase speed, move to the back, decrease speed. Keep it simple!

BTW, this is the wrong thread. You can post questions here:
 

wsimpso1

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Saline Michigan
They thought this something in the boat racing too. Turns out all your doing is trying to make a crush proof coffin as no one can survive the rating and the weight of building such a structure is tremendous
Maybe making a boat cockpit that will stand anything it might see in a high speed disintegration is tough, but airplanes at 26 g is quite doable and at little added weight.

Human tolerance to low duration g pulses is way out there. 26 g is not much of a problem for us. Much data out there on this. Our member SVSUSteve has written about this and cites data on human g tolerance. With suitable restraint we can take short pulses to 26 g without a whole lot of trouble. With other devices, like HANS, human tolerance is substantially higher still.

Here is a thread on the topic:

A 26 g pulse is actually in the the regs (Part 23 aircraft must pass this test) for structural integrity of seats and seat belts - nothing else in the cockpit of an airplane has to pass it, but the seats and belts do. The idea is that you will usually survive that pulse if the seats stay in their mounts, the seatbelts keep you on the seat, and you do not hit your head on anything solid. The pulse required is axial with a 10 degree lateral offset - think center punching an obstacle with a bit of yaw at impact. The regs also specify that the seats and seat belts stay put in a 19g up and back pulse - think hard pancake landing. Lots of airplanes certified and flying under this requirement.

Going further is to make the cockpit sturdy enough to keep the cockpit clear of things intruding and keeping the crew from hitting hard structures within, but this is not currently required by regulation. In Experimentals, we are on our own to do or not do any of this.

In my design, I found that min gage on the fuselage (22 oz TRIAX outside, 18 oz BIAX inside, 3/8" Divinyvcel foam core) had already gotten me well above +/-6g vertical with an FOS of 2.0. Part of that was a roof that would not crush onto me in a nose-over, so that helped too. When I checked the 19g and 26 g cases, I found that I was already in the ballpark, so I did some more selective reinforcement of the cockpit area and passed those as well. So, a cockpit built to stand these pulses is really not out of range. No, I did not physically test the cases, but I did run them analytically for my one-off airplane.

Steel tube fuselages have a good reputation for occupant protection hard landings and in post-landing obstacle impacts. I suspect that many of them are either a pass or are close on the Part 23 19g and 26g cases.

Billski
 

TarDevil

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Jun 29, 2010
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Coastal North Carolina/USA
According to Elliott's and Justin's flight test regimen, today at best will be high speed taxi... assuming his prior visits accomplished all they wanted for paperwork, inspection and slow taxi.
 

JeffTaylor

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Apr 6, 2020
Messages
3
From one of Elliot's videos:

Prototype program:
Day 1: Inspection / paperwork
Day 2: Engine runs / low speed taxi
Day 3: High speed taxi
Day 4: 1st flight
Day 5: Post flight Inspection
Day 6: 2nd flight
 

TarDevil

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Jun 29, 2010
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531
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Coastal North Carolina/USA
From one of Elliot's videos:

Prototype program:
Day 1: Inspection / paperwork
Day 2: Engine runs / low speed taxi
Day 3: High speed taxi
Day 4: 1st flight
Day 5: Post flight Inspection
Day 6: 2nd flight
They did Day 1 and 2 on their last visit, unless they insist on a re-inspection. I certainly woulld.
 

UAVGuy

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May 1, 2020
Messages
18
Any comments on the canard and main wing lift spreadsheet calcs and the rotation speed ?

Or how about the prop clearance ?
 
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