pictsidhe
Well-Known Member
Aircraft AOA will be slightly reduced. Much less than Peter's guess.
10/23 Raptor Video
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That's what I said in post 156.
flywheel1935
Well-Known Member
As I understand, by putting more weight in the nose ( ie; existing ballast, not extra weight ) then the canard carries more weight, while the main wings carry less. Guess that will require more nose trim ??? keeping the elevator in a more down position, as the canard itself cannot be trimmed separately.
Even though I think moving the cg forward is absolutely the right move, it will not decrease drag. The canard will have more camber with a bigger slot and it will make bigger tip vortices.
Several degrees less aoa is not going to happen. 3 degrees less would represent a massive loss of lift. Something like 1000lbs
Several degrees less aoa is not going to happen. 3 degrees less would represent a massive loss of lift. Something like 1000lbs
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Yup
However all the above is simple academics. The AOA decrease in main wing will be tiny as unloading it by only 30# or so wont make a dang of difference on a 3600# MTOW. Two knots of increased Vr would do far more. So the bobbing and pitch instability wont be effected by these changes. Indeed, Velocity wrote in the Youtube comments that he thought the Raptor was 'nibbling at the stall' in the first flight. If that is true then increasing canard loading will just make the bob worse.
Increasing the static margin by rearranging weight distribution (and not increasing) will load the canard more and unload the wing. This will reduce the wing AOA and increase the canard AOA required for flight at any given speed. Of course the canard incidence is fixed although as elevator is actuated further, the effective canard AOA does increase to compensate for the reduced main wing AOA. That is up to the maximum elevator angle or canard stall, whichever occurs first.
However all the above is simple academics. The AOA decrease in main wing will be tiny as unloading it by only 30# or so wont make a dang of difference on a 3600# MTOW. Two knots of increased Vr would do far more. So the bobbing and pitch instability wont be effected by these changes. Indeed, Velocity wrote in the Youtube comments that he thought the Raptor was 'nibbling at the stall' in the first flight. If that is true then increasing canard loading will just make the bob worse.
flywheel1935
Well-Known Member
Just a thought, how many airfields in the States have diesel on tap ??? gather Jet-A1 is too damaging on the fuel pump/injectors. can you imagine filling 121 gallons in 5 gallon jerry cans from the local gas station.
this was a question asked in the latest YT video.
this was a question asked in the latest YT video.
Most everywhere in the north a local heating oil company will deliver #1 heating oil/diesel to anywhere including the airport. I don't know about the south.
Off road diesel is cheaper (red dye ) with no road tax sold at farm stores.
Off road diesel is cheaper (red dye ) with no road tax sold at farm stores.
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Hephaestus
Well-Known Member
Around these parts... If the airport is big enough to own a plow there's diesel onsite.
Not exactly in fuel your plane configuration.
But fuel delivery to an airport isn't a challenge - lots of businesses setup to do this for mobile equipment (manlifts, zoombooms, construction generators). Fairly cheap to have delivered no jerry cans required.
Not exactly in fuel your plane configuration.
But fuel delivery to an airport isn't a challenge - lots of businesses setup to do this for mobile equipment (manlifts, zoombooms, construction generators). Fairly cheap to have delivered no jerry cans required.
Ok guys, what is being done is moving 50 pounds from the cabin to the nose. Total lift will be the same, a small reduction in lift from the main wing, an identical increase in lift for the canard. Small decrease in lift on the main wing will require a decrease in main wing AOA, the canard will also make the same small decrease, and then the elevator will have to be deflected down to increase lift from the canard enough to make the additional lift. How much AOA change? Tiny, in proportion to the change in lift. I suspect we will take 15-25 pounds off the main wing, which is carrying somewhere north of 2000 pounds. Yeah, less than a 1% reduction of Cl. Tiny to the point of being almost immeasurable, but you will be able to measure the increase in downward deflection of the elevator to carry the additional load on the canard.
Billski
Marc Zeitlin
Exalted Grand Poobah
I addressed the problems with that theory (which cannot be true) in post #70 on page 4 of this thread.
pictsidhe
Well-Known Member
In one of the recent videos, it looked like the canard flap slot has a large diffusing angle. I'm fairly sure that that won't work as Roncz intended.
I was looking at model turbine engines the other day and while they can run on both diesel and jet A, you are required to use more oil on jet fuel.
I'm not sure how much of a difference that makes for an Audi, but I thought it was interesting.
I'm not sure how much of a difference that makes for an Audi, but I thought it was interesting.
Fuel delivery to an airport is a giant paperwork PITA. Recurrent training required, truck inspections, airport security badges, etc, etc. And I live in rural Alaska. Not saying it can't happen, but I wouldn't say it's no big deal. We don't have a #2 diesel delivery truck set up to be on airport, all our d2 deliveries are outside the fence. A traveling diesel powered airplane needs to be able to burn JetA/#1deisel/stove oil/kerosene. And if anyone wants to argue the difference between #1deisel/stove oil and JetA, ours comes out of the same tank on the barge, just goes in different tanks in our tank farm.
flywheel1935
Well-Known Member
I think that was my point, in that fueling the Raptor could???? pose serious logistical issues, bit like buying an electric car and charging points not available, not very good market research done then, ref availability !!!
Turd Ferguson
Well-Known Member
Airport politics aside, I can’t imagine a fuel jobber willingly becoming part of the liability pool by pumping diesel into an airplane.
TFF
Well-Known Member
I’m assuming the jobber is supplying a fuel tank for storage? A big operation like an airline has documents out the wazoo to not mix up fueling even if it’s common sense. Paperwork is what counts. A regular GA airport depends on who runs it. My airport does not allow private fuel. We would have had it if we could. We were the third biggest fuel user at the airport. If you can buy a whole truck of fuel, it’s about half of sale price.
If the future politicians ban leaded Avgas.... the diesel guys will suddenly be very popular.
Maybe the airport can sell JetA/diesel blend?
Maybe the airport can sell JetA/diesel blend?
We'll just switch to UL. The conversion to diesel would kill most of the GA fleet. Who's gonna spend $100k to re-engine a $50K Cherokee or C-172?
Getting a diesel tank at your home airport may be doable, but that is only a partial solution. You need to be able to refuel almost anywhere for the plane to be useful. Having diesel delivered to whatever airport you need it at would be a huge logistical pain.
That Audi diesel has to burn Jet A to make it a useful aircraft. No idea what additives that would take, but that's getting way ahead of where the Raptor is, anyway. Worry about that when/if the thing is capable of reaching another airport.
That Audi diesel has to burn Jet A to make it a useful aircraft. No idea what additives that would take, but that's getting way ahead of where the Raptor is, anyway. Worry about that when/if the thing is capable of reaching another airport.
