Aero Ex - Valkyrie 1 Design

[Peasant_Pilot]

What are people's thoughts on stabilator vs elevator?  I like things relatively traditional but I'm curious top hear people's thoughts on it

[Thruster88]

The musketeer has a stabilator so for the pilot I would say it makes no difference. Engineering on the stabilator is possibly more complex. The anti servo tab linkage has to be correct to get the control feel required for a certified aircraft. Conventional elevator is more popular, there must be a reason. 

[RFguy]

I love my Stabilator (PA28) but I love complexity.... Stuart is right about  the anti servo tab linkage.... there is a bit to it.... Stabilator is more efficient, for sure, and more effective.... but at considerable complexity...   Like I love my multi-link Oleos on my PA28, great on the rough, and  like I love the stabilator- so much range. But the Oleos are a maintenance PITA . As I also have aJabiru - I appreciate the simplicity of the jabiru control surfaces and cable system, and I appreciate aircraft using spring steel or 'glass etc sprung main gear (Cessnas, Jabirus) . I only really appreciate the simplicity after running maintenance on the Piper for a couple of years. Sure they're really nice to use, makes the airplane super nice....(Oleos, Stabilator ) makes for a royal aircraft..... but at maintenance PITA which I would not recommend for an RA-aus level of maintenance  and $$$ spent. 

[skippydiesel]

My T tail Zephyr had a relativly small (to my eye) horizontal stabiliser (with elevator) and a large rudder.

 

Aesthetically I didnt much like the concept but grew to appreciate it. Great rudder and elevator authority, right down & through the stall - couldn't ask for better. X wind landings/TO handled with ease.

 

Aside from aesthetics, why do most gliders and a few small powered aircraft have aT tail, while most do not?

[pmccarthy]

Stabilator on the Vixxen works really well. I previously had a PA-28 so appreciate it.

[Thruster88]

1 hour ago, skippydiesel said:

My T tail Zephyr had a relativly small (to my eye) horizontal stabiliser (with elevator) and a large rudder.

 

Aesthetically I didnt much like the concept but grew to appreciate it. Great rudder and elevator authority, right down & through the stall - couldn't ask for better. X wind landings/TO handled with ease.

 

Aside from aesthetics, why do most gliders and a few small powered aircraft have aT tail, while most do not?

AI Overview

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Sailplanes use T-tails primarily for operational reasons, not aerodynamic ones: 

 

• Clearance: Sailplanes have a tail skid or tailwheel and a single main wheel landing gear. When the glider is resting in the wing-down position, one wingtip touches the ground and the aft fuselage is small in diameter. A low-mounted horizontal tail would be too close to the ground or even touch it. A T-tail moves the horizontal tail up enough to clear the ground.

T-tails are also used on other aircraft for a variety of reasons, including:

• Removing the tail from the exhaust blast: T-tails are popular on aircraft with aft fuselage mounted engines. 
   
• Keeping the horizontal surfaces away from water: Seaplanes and amphibian aircraft often have T-tails to keep the horizontal surfaces away from the water. 
   
• Increasing the effectiveness of the vertical tail: The horizontal stabilizer acts like a winglet, reducing induced drag of the rudder. 
   
• Increasing clearance at the rear: T-tails can be used to increase clearance at the rear of a cargo aircraft. 

[Peasant_Pilot]

It's interesting, I remember reading about the Cobra Arrow, it originally had stabilators on it, but they had some issues with Pilot induced oscillation, so they switched to elevator in a later version to negate it. just had me curious

[Peasant_Pilot]

So last night I burned through the night to redesign the tail section, I've been really happy with the profile of the aircraft but I always had in my head id have to really beef up the tail section due to it being quite small in the tail end Cross sectionally, so I've incorporated the vertical stabilizer more so it's more as one structure instead of seaming like a separate entity, iv increased the size a little of the top and bottom strakes and essentially created a much stronger cross section, while I still need to get used to it, I feel this is more where it needs to be structurally. I ended up 3d printing some 10% scale tail sections of both and doing some twist tests on it and the new design was far superior in strength and resistance to twisting. Obviously, it's not the same thing but it's a proof of concept to a degree.

 

see in the picture the comparison to the previous design in the tail section to the new one, new design is on the bottom. ill also add in a couple of colour renders to see what you think

[rgmwa]

Good idea carrying the rudder all the way down. Should help spin recovery. 

[RFguy]

well, this is a Lanceair 320/360, for reference.  76 sq ft of wing.... there were a couple of different wings.

[Peasant_Pilot]

the JMB VL3 has a similar tail too and to a lesser extent the WT9 Aerospool. id say it would have to work, and these planes are going quick too

[RFguy]

How many sqft of wing do you have at the moment ?     Lancair of course is not in the same race / category at what you are proposing , a different beast.

The Lanceair foil, type NLF-0215 is worth studying. it is a new foil from the 1980s.

Have a look at NASA technical report 1865  .   (June 1981 ).. it is in there.... it isn't all plain sailing though, the super-duper airfoil is quite sensitivie to flow disruption (bumps turbulence etc etc) 

https://www.n91cz.net/Interesting_Technical_Reports/NASA-81-tp1865.pdf

 

Retract : Cirrus does pretty well with non retract, I'd suggest same. Many small GA planes are retract just so they can be commercial trainers. Hanging around  a maintenance facility, I can tell you that retractable gear systems -  is probably problem child #1 and in general, never quick to solve due to the sheer numbers of joints, switches, pressure sensors, pumps, motors, relays O.M.G !!!!!

 

[rgmwa]

FWIW the RV-12 has 127 sq ft with a constant chord wing and MTOW 600 kg. Sling 2 also has 127 sq ft but with a tapered wing, although I'm sure you already know that as it's one of the aircraft you mentioned previously. Agree that retracts are not worth it in this class of aircraft. As has been mentioned, none of the RV's have them and they perform very well.

[Peasant_Pilot]

2 hours ago, RFguy said:

How many sqft of wing do you have at the moment ?     Lancair of course is not in the same race / category at what you are proposing , a different beast.

The Lanceair foil, type NLF-0215 is worth studying. it is a new foil from the 1980s.

Have a look at NASA technical report 1865  .   (June 1981 ).. it is in there.... it isn't all plain sailing though, the super-duper airfoil is quite sensitivie to flow disruption (bumps turbulence etc etc) 

https://www.n91cz.net/Interesting_Technical_Reports/NASA-81-tp1865.pdf

 

Retract : Cirrus does pretty well with non retract, I'd suggest same. Many small GA planes are retract just so they can be commercial trainers. Hanging around  a maintenance facility, I can tell you that retractable gear systems -  is probably problem child #1 and in general, never quick to solve due to the sheer numbers of joints, switches, pressure sensors, pumps, motors, relays O.M.G !!!!!

 

has 107 sq ft of wing area as it sits, attached is a quick spec sheet to give some more insight, and while I'm tinkering away with a retract option, ultimately it will be standard fixed tricycle. I firmly believe for RAUS it is the most suitable

[RFguy]

have you got pilots sitting over the wing spar, in front, or behind ?

 

I'd also like to see +6g for these planes, so the Va doesnt get too low.  

IMO, that's a potential hazard in these land-slow but  fly-fast slippery airplanes. 

120 kts (IAS) is not that much use if Va (clean , at half fuel and  1 POB) ) is 75 kts etc.

Edited December 28, 2024 by RFguy

[Peasant_Pilot]

Essentially sitting between the spars, seating is at 35 degrees

 

I'm aiming for a safe +6 - 4g's

[RFguy]

between- as in forward, aft of mainspar of person CoM on the spar? What's the CoG location look like with no fuel in the fuel tanks (assuming forward of mainspar)  and max people and baggage ?

I see a few low wing aircraft that with nothing in the tanks(which are often forward of the mainspar) and full peeople and baggage, marginal CofG condition.

[facthunter]

In the stipulated range is safe. Anything else Isn't. The plane is not airworthy.   Nev

[Peasant_Pilot]

6 hours ago, RFguy said:

between- as in forward, aft of mainspar of person CoM on the spar? What's the CoG location look like with no fuel in the fuel tanks (assuming forward of mainspar)  and max people and baggage ?

I see a few low wing aircraft that with nothing in the tanks(which are often forward of the mainspar) and full peeople and baggage, marginal CofG condition.

Working through that over the next few weeks to make sure it's going to work where it is. Will keep you upto date

[Underwood]

On 28/12/2024 at 8:32 PM, RFguy said:

between- as in forward, aft of mainspar of person CoM on the spar? What's the CoG location look like with no fuel in the fuel tanks (assuming forward of mainspar)  and max people and baggage ?

I see a few low wing aircraft that with nothing in the tanks(which are often forward of the mainspar) and full peeople and baggage, marginal CofG condition.

Some of these designs have the Pilot/pax seated some way aft of CoG and people have got a lot fatter since design was initialised, doesnt help.

One of the reasons I think we now have the rather silly imo 600kg microlight class in the  uk