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May 21, 2019, 01:57 PM
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richard hanson's Avatar
Quote:
Originally Posted by xlcrlee
Richard you know darn well they never said or even thought that. Maybe you've already had enough today ....?
Of course
but noting they both have similar L-D, leads the unwary to assume the y are a good glider-
I would suspect however that the old Switzer VNE is similar to the minimum flying speed of the big Boeings
Last edited by richard hanson; May 21, 2019 at 02:02 PM.
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May 21, 2019, 02:04 PM
AndyKunz's Avatar
Quote:
Originally Posted by ShoeDLG
If one of the motors fails in fan-borne flight, you’re dead.
1 fan motor = 3% power loss. I doubt it's designed to be that marginal on power.

Quote:
If one of the articulation systems fails in fan-borne flight, you’re dead. I count at least 6 “single points of failure” in that configuration... simply not viable for carrying people.
If you assume the articulation system is independently actuated, then yes. If you assume that there is some mechanical interconnect, perhaps even with a mechanical interface accessible to the pilot, then it is less likely.

I'm sure the engineering team will receive plenty of scrutiny from the authorities for safety considerations, and from their own insurance carrier for liability reductions.

Andy
May 21, 2019, 02:04 PM
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Quote:
Originally Posted by richard hanson
Of course
but noting they both have similar L-D, leads the unwary to assume the y are a good glider-
I would suspect however that the old Switzer VNE is similar to the minimum flying speed of the big Boeings
And "unwary" brings us right back to the Bad-Boy Boeing thread (I jest)
May 21, 2019, 02:11 PM
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richard hanson's Avatar
Quote:
Originally Posted by xlcrlee
And "unwary" brings us right back to the Bad-Boy Boeing thread (I jest)
Please ! Please !- enough is enough.
BTW- VNE 157 mph on the Switzer-
less than mins on the biggies
"similar glide--------"
May 21, 2019, 04:24 PM
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ShoeDLG's Avatar
Quote:
Originally Posted by AndyKunz
1 fan motor = 3% power loss. I doubt it's designed to be that marginal on power.
I wasn’t referring to the Lilium design, I was referring to the three-fan configuration in the picture Richard posted. If you lose power to or control over any of those three fans in or near hover, you will be out of control. Valid RC design, but nowhere close to being viable for carrying people.
May 21, 2019, 04:57 PM
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richard hanson's Avatar
A bit like the Osprey?
How that thing got beyond the table napkin sketch stage, defies logic.
I guess the “logic of lobbies” prevailed
To clarify,
Lobbies hold more power than logic for today’s military spending
Last edited by richard hanson; May 21, 2019 at 05:03 PM.
May 21, 2019, 05:26 PM
Flying R/C since 1964
kallend's Avatar
Thread OP
Quote:
Originally Posted by ShoeDLG
I wasn’t referring to the Lilium design, I was referring to the three-fan configuration in the picture Richard posted. If you lose power to or control over any of those three fans in or near hover, you will be out of control. Valid RC design, but nowhere close to being viable for carrying people.
A regular conventional helicopter has one lift rotor and one tail rotor, each of which can fail and cause a crash.
May 21, 2019, 05:58 PM
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richard hanson's Avatar
At least, the copter has an outside chance of autorotation
On a lighter note --- I have one of the little 49.95 quad/ wing thingys , Inductrix Switch, which looks like it might possibly glide (dream on)
A few tests demonstrated that weight overcomes the puny wing area and it drops like a rock when power is shut down.
But if you have not tried one -- do so --it has an absolutely great stabilization setup and can be flown safely in a WC
Last edited by richard hanson; May 21, 2019 at 06:11 PM.
May 21, 2019, 06:53 PM
Registered User
Richard, one must remember that the Marines have a "difficult lifestyle" and sign up knowing that they can die. So flying in a much slower helicopter provides a greater risk of getting shot down even before they reach their assault target because I suppose a slow target is an easier target AND is in the air longer, providing more time to get shot down. Even crashing during practice exercises is still a necessary part of an overall mission profile. Surely there were tradeoffs made, but ya' just gotta leave it to the Marines. Anyway we'll soon have cyborg planes and soldiers, some with thick Austrian accents.
May 21, 2019, 07:12 PM
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richard hanson's Avatar
You see the issues with the absolute clarity I only expected to find in Washington.
May 21, 2019, 07:44 PM
AndyKunz's Avatar
Quote:
Originally Posted by ShoeDLG
I wasn’t referring to the Lilium design, I was referring to the three-fan configuration in the picture Richard posted. If you lose power to or control over any of those three fans in or near hover, you will be out of control. Valid RC design, but nowhere close to being viable for carrying people.
In that case I agree with you. I thought lilium was the subject.

Andy
May 21, 2019, 10:05 PM
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ShoeDLG's Avatar
Quote:
Originally Posted by kallend
A regular conventional helicopter has one lift rotor and one tail rotor, each of which can fail and cause a crash.
It depends very much on how they fail... loss of torque to a helicopter main or tail rotor is often very survivable. A mechanical failure of the tail rotor is potentially survivable as well. A mechanical failure of the main rotor is likely lethal. The good news for a helicopter is that mechanical failures of the main rotor are exceedingly rare (provided you don’t hit something).

Compare this with a 3-fan multi rotor... loss of torque to any one of the fans will result in loss of attitude control and a very bad outcome. This is fundamentally different from a helicopter.


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