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John235's blog
Posted by John235 | May 09, 2012 @ 01:33 AM | 2,149 Views
Since flying my 60" canard slope soarer from 2010, I'm still looking for improvements. There are two obvious ways to improve the performance of a canard sailplane: 1) Make a bigger wing with higher aspect ratio, and 2) Use less canard area relative to the main wing so there is less interference. Along these lines I propose a new prototype slope soarer as shown in the attached images. The new design has a revised planform for the main wing which I expect will offer lower drag in the turns. The winglets on the canard have disappeared because they are only beneficial at the low end of the speed range, ie. not the main priority here.

Main wing:
span = 77"
area = 535 sq"
Root chord = 7.87"
Tip chord = 5.5"

Canard wing:
span = 19.7"
area = 72 sq"
root chord = 4.14"
Tip chord = 2.95"
Posted by John235 | Mar 12, 2010 @ 07:40 AM | 3,404 Views
This model was designed in the early months of 2009, and construction was completed in March 2010. I have implemented changes following experience gained with my earlier 48" canard soarer. This 60" span soarer has been developed with the aid of XFLR5 computer simulation. It has improvements in the following areas:
* Reduced size of canard wing with lower aspect ratio.
* Hinged canard elevator.
* Elevated mounting of canard wing.
* Optimised wing-tip for canard wing to improve stall charasteristics.
* Increased sweep-back angle of main wing also with higher aspect ratio.

Maiden flight successfully performed at Otford NSW, Australia, 12th March 2010.
Posted by John235 | Feb 04, 2010 @ 07:12 AM | 4,338 Views
This is my second canard soarer. Again it is my original design. One of the main design objectives was to minimise the drag penalty of the forward wing. Instead of using a canard elevator, this model uses elevons and flaps on the main wing for pitch control. The forward wing airfoil is 8.7% thick. I was mostly satisfied with the performance of this model. The aerodynamic efficiency isn't the greatest, but it does have good penertation ability and handles nicely. The stall behavior is especially good. The model is predictable and easy to land when crow-braking is used. I think that crow-braking is very desirable (perhaps essential) on a canard soarer. The biggest disappointment of this model was the fuselage construction was too delicate for use on the slope. In Feburary 2009 the fuselage was smashed into a rock when the model was flipped in a nasty rotor. I did not rebuild the model because I decided I would rather build a new prototype to try out some possible design improvements.

Specs:
Main wing - Span = 122cm (48"), Area = 2148cm^2 (333.0sq"), Airfoil = SD7003 blended
Canard - Span = 50cm (19.7"), Area = 437cm^2 (67.7sq"), Airfoil = AG35
Weight = 0.58kg (20.5oz)

Build Details:
Slope soarer main wing (2008-07-02)
Slope soarer forward wing (2008-07-11)
Fuselage construction (2008-07-16)
Construction completed (2008-07-24)
Test flown (2008-08-07)

Instead of rebuilding the fuselage after the crash, I decided to build...Continue Reading
Posted by John235 | Jan 31, 2010 @ 11:46 PM | 4,500 Views
Here is some info about a small canard glider that I designed and built. The model flys ok but I don't consider it a complete success. The good news is that it can fly fast and handle well in windy conditions. The bad news is the elevator control is unpredictable in low speed flight and the glide ratio is worse that I hoped for. I can take this model to the slope when the conditions are light but I would only really fly it for the novelty value.

My impressions based on my experience with this model:

1) For small canard models it can be difficult to get enough elevator authority when relying on canard elevator alone. I think it is important to choose the airfoils and aspect ratios carefully to avoid this type of problem.

2) It was probably a bad idea to use an airfoil with 10.5% thickness for the canard wing. Applying the canard elevator worked like an air-brake. The lift to drag ratio would have been very poor due to the low reynolds numbers for the canard wing.

3) I think that gliders using the canard layout tend to peform better at the upper end of the speed range. This makes them better suited to slope soaring than thermal soaring.

Specs:
Main wing - Span = 112cm (44"), Area = 1745cm^2 (270.5sq"), Airfoil = AG36
Canard - Span = 48cm (18.9"), Area = 406cm^2 (63.0sq"), Airfoil = S7055
Weight = 0.27kg (9.5oz)

Build details:
Introduction (2007-11-23)
Forward wing design issues (2007-11-27)
Wing Construction I (2007-12-17)
Wing Construction II (2007-12-22)
Dihedral and tail fin calculations (2008-01-09)
Forward wing construction (2008-02-05)
Fuselage plan (2008-02-15)
Canard HLG completed (2008-03-02)
Canard HLG flight testing (2008-03-03)
Posted by John235 | Jan 23, 2010 @ 01:38 AM | 3,352 Views
Here is some info about the first successful canard model that I built. (this was my previous unsuccessful attempt). It has 80cm wingspan and weighs 510g. It is a reasonably quick model, without being like a pylon model. It glides very nicely with the power off and landings are always a delight. I have been flying this model on countless flying days since it was completed in 2007. It gives quite long fight duration - I can fly an easy 10 minutes of aggressive flying using 1300mAH 3S lipo. The only incident so far was a nose-in due to inadequate launch speed. The fuselage was broken badly, but fortunatly it was not too hard to repair.

The model uses a hinged canard elevator which provides adequate pitch control. However I have since programmed flapperon mixing on my transmittor so the ailerons reflex upwards by about 2 or 3mm when full up elevator is applied. I am very happy with this mixing scheme because it provides very positive pitch control while retaining predictable stall behaviour.

Specs:
Main wing - Span = 80cm (31.5"), Area = 1290cm^2 (200sq"), Airfoil = NACA1411
Canard - Span = 37cm (14.6"), Area = 296cm^2 (46sq"), Airfoil = E205 modified.
Weight = 0.51kg (18.0oz)

Build information:
My new project (2007-07-20)
Some build progress (2007-08-15)
Wing structure completed (2007-08-21)
Canard for my canard (2007-08-24)
Fuselage construction (2007-09-04)
Ready for testing (2007-09-13)
Test success (2007-09-15)
Powered maiden (2007-09-19)
Posted by John235 | Apr 28, 2009 @ 04:32 AM | 3,686 Views
dat files attached. Created from S3021 using Profili.