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Q2 Stall Speed

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6 years 8 months ago #1467 by Lukarr
Q2 Stall Speed was created by Lukarr
Good morning
Is it possible to alter the Q2 to achieve a stall speed of 45 knots?

cheers

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6 years 8 months ago #1468 by admin
Replied by admin on topic Q2 Stall Speed
Yes . . . alter the building materials to wood, fabric, and metal . . then change the form of the plane to look more like a Piper Cub . . . this should achieve your mission goal.

Building it to plans will not. FYI.

The plane was designed to be FAST and efficient . . . not SLOW or DRAGGY.

Please let me know if this helps.

Thanks,
Dan Yager
QBA Editor
www.quickheads.com

Flying an aeroplane with only a single propeller to keep you in the air. Can you imagine that?

— Captain Picard, from 'Star Trek: The Next Generation' episode 'Booby Trap.'
The following user(s) said Thank You: CharlieN

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6 years 5 months ago #1491 by scheevel
Replied by scheevel on topic Q2 Stall Speed
If you want to build a "Q-2" style plane that will stall around 45 knots, then build a dragonfly (stalls at 48 kts). It can land fairly slow, but will also only cruise at around 115 knots. Plenty of dragonflies and or kits are available.

Jay Scheevel

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6 years 3 months ago #1515 by AlanThomas
Replied by AlanThomas on topic Q2 Stall Speed
I am a new member who has just purchased a Q2 in New Zealand which has not been flown for some time with myself not yet having a licence to fly. Let the fun begin. Thank you for this very excellent site.

On the question of stall speed it does seem that it is not possible to actually stall but rather instead enter into a hysteresis of bobbing along whereby the loss of left induces additional speed thus preventing stall. Is there really any mechanism that can induce a true stall? Perhaps a bigger belly board?? my understanding is that with no thrust this pre-stall bobbing will result in a controlled descent of around 900 ft./mat around 70 mph and not even being able to induce a spin to induce a stall including with the stick right back. an additional feature is that there seems to be an excellent glide ratio, be it the figures being somewhat inconsistent.

I was hoping that my Q2 could be re-registered as a microlight (Ultralight)as costs involved such as maintenance, pilot licence and suchlike is much lower. The Q2 well within the weight spec but still requires a stall speed of 45 kn when configured for landing. It has the T-Tail and Aileron Reflexor. with these two items in a neutral setting my Q2 flies at 50 kn.

What should I expect with the Aileron Reflexor fully deployed so the main wing provides maximum left while at the same time the T-Tail deploys in a manner that gives maximum pitch angle while the canard elevators are providing almost maximum lift with a slight capacity for skyward authority? It appears that the Aileron Reflexor deployed may lower the landing speed a bit over 5 kn. Does anyone have any actual information? Apparently the with the T-tail properly configured at around 50 kn a neutral position of the canard elevator is achievable with further adjustments between the elevator and T-Tail bringing the landing speed down even further. Of course when approaching for a three point landing entering into the ground effect causes a slight speed up.

I understand that the speed brake belly board alters the pitch angle while lowering the speed. My Q2 is not fitted with a belly board so I do not have any information from the log book on the subject. I think I will fit one because New Zealand does not have a good supply of long runways.

In New Zealand we are allowed a constant speed variable pitch prop for microlights (ultralights) which of course adds another dimension to the issue of minimum speed.

I was hoping to find some authoritative information given that the test pilot reports in the log book 42 kn so as to satisfy the civil aviation authority.

Another fellow in New Zealand who built a dragonfly (winning best home built construction in New Zealand) claims that he is able to achieve lower than 45 kn configured for landing.

New Zealand has accepted the single seater quickie as a microlight (ultralight) in the 1990s. Would it be fair to say that both the Q1 and Q2 have the same canard and mainwing set up/dimensions? The wings have a 40/60% shared loading. What is the relationship of the few as large as being a lifting body between these two aircraft?

I suspect that inconsistency of figures is as a result of the inconsistency of construction combined with the entirely different flying characteristics of an aircraft either not having landing flaps or not having T-Tail and Aileron Reflexor in order to set up for a lower landing speed.

I have the impression that the quickie style would become extremely popular if they could be registered as microlights (ultralights).

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6 years 2 months ago #1519 by scheevel
Replied by scheevel on topic Q2 Stall Speed
Welcome to the quickie universe. I think you are suffering from some major misconceptions about the airplane and flight in general. The basic issue on any aircraft that determines stall speed is wing loading. This means that for a given weight the wing area limits the stall speed to within a narrow range, regardless of wing configuration. So, amount of lifting area is king. Please have a look at my 3 part series on Q-2 aerodynamics under the Q2/Q200 tab at the top of this website to see what can be achieved with a Q-2. The lowest achievable airspeed in a perfect circumstance at 900 pounds gross weight and optimal use of reflexor is about 66 MPH (57 Kts.). The Q-2 has about 68 square ft. of wing area. The dragonfly has the same wing configuration as the Q-2, but has a lot more wing area (92 square feet), so that is why it lands slower. The belly board does nothing but add drag, making the plane assume a more nose down attitude and higher descent rate. It does not change the critical stall speed. You will have to violate the laws of physics to get the Q-2 to stall at 42 knots. Maybe if you install full length Fowler flaps and leading edge slats on both canard and main wing and you may be able to establish effective wing area to 100 square feet in the landing configuration, but the mechanisms and mods required to do this would probably add 200 pounds to the plane and make it infinitely more complex to build, fly and land. Better get a plane that is more suited to your desires.

Jay Scheevel

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6 years 2 months ago #1520 by AlanThomas
Replied by AlanThomas on topic Q2 Stall Speed
Jay thank you very much for your prompt and very informative reply. Prior to being a member I was unable to the access some of the material you have prepared from your very careful studies achieved without a wind tunnel which I have at this stage had a simple read through but will go back and study your material carefully.

In the meantime I'm wondering if you or other members of the site, with the appropriate expertise and/or experience such as yourself, could enlighten those of us would like to explore the low speed aerodynamics further. When of course we determine centre of gravity on the ground we do it simply by balance but in real terms the centre of gravity is the pivot point based on the aerodynamic wing loading. With the Q series the information available examined so far indicates this is a very complex equation to predetermine for the purpose of optimum pitch and lift due to the twin wing configuration with different pitch angles and variable configurations and computations resulting from canard elevator, canard aileron, canard pitch angle, mainwing, aileron, reflexor and of course the effects of a T-Tail. I agree that the belly board should not be part of the equation unless a belly board was constructed in the manner of a third wing close to the probable centre of gravity(like those extra wing covers a ladybird deploys that in themselves provide considerable lift).

As the Canard and main wing share the duty of the left in the neutral configurations at 60%/40% obviously this is not so when manipulating the various control services above when approaching stall speeds of both wings particularly since they have different pitch angles. we also must not forget the importance of the optimum patch angle of the fuselage itself as that is a considerable lifting body which brings me to the point as to what percentage lift the fuselage is contributing in conjunction with the wings. Obviously if the landing invigoration does not take maximum advantage of the fuselage lifting body we have the wrong configuration. This then adds a substantial difference to the data gathered about the wings only. To give an example of the forces involved with the fuselage An F-15 is capable of straight and level flight in the absence of an entire wing with the additional capability of achieving landing speed without stalling (aerodynamics of stalling the fuselage).
en.wikipedia.org/wiki/Lifting_body

When addressing the effects of the fuselage as a lifting body just from a rudimentary examination the Q2 series appears to have a fuselage that would not go into stall until extremely low speed without regards to the wings. The Dragon series fuselage does not seem to provide as much lift.

other factors such as removing the wheel pods from the canard reduces lift from the canard in two ways, one being the effective when characteristics of the pod itself and secondly removing the "winglet" effect that the pods provide.

Clearly the Q series has been optimised for speed hence the name "Quickie".
My question addresses the issue of optimisation for purposes of achieving a slower speed prior to losing capacity for flight with essentially the same componentry and readily available add-ons.
Do we have any information on the actual optimum pitch angle and deployment of elevators functioning as Flaps of the canard prior to stall?

Do we have any information on the actual optimum pitch angle and deployment of The actual ailerons functioning as Flaps prior to stall?

Do we have any information on the actual optimum pitch angle Of the fuselage prior to stall?

This information is of course the foundation information prior to determining what can be done with flaps and suchlike.

What do you think should be made of the test pilots notes, the previous owner's notes and reports of others claimant to achieve speeds under 45 kn? Here we have a conundrum whereby your theoretical approach using physics is being directly challenged by the claims of various individuals while other individuals of equal standing are reporting far higher speeds where loss of flight is occurring by way of entering into the bobbing effect, be it perhaps prematurely due to a host of different possibilities. I absolutely agree that more wing area is needed for a more reliable result in the low speed range. The only question I raise in regards to this physical fact is the lifting properties of the fuselage which I have not been able to find any figures whatsoever. Perhaps I should buy a scale model and build myself a wind tunnel so as to determine whether or not I should address the rather complex problems of reconfiguration of wings and flaps. The only thing I don't agree with is the extent of the weight addition you have suggested but accept your comment as an expression of difficulty rather than an absolute.

Further to you raising the issue of increasing wing area in the form of more radical flaps I absolutely agree with you but I am primarily interested in a satisfactory result under 45 kn while maintaining control authority. provisionally I think the elevator is and ailerons could be removed and replaced with completely redesigned devices that while having some complexity would only increase the overall weight by about 10 or 15 KG including the stepper motors that would deploy them. Actual component costs would be in the region of $500. Effect on top speed I think would be insignificant.

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