Sanjay sir even mine on this week I guess.. will upload the pics soon.. my first spad...

Only decor works left...
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Good luck Arun

Guess this is Yet "yet another Avispad"   

After the crash I had, I wanted to rebuild the Avi. But also wanted to improve the build.

I had built a Corroplast Cub, with a semi-symmetrical wing, 51" span and 8 1/2" + 1 1/2" chord

As most of my crashes involve bust fuses, and intact wings, I decided to make an Avi fuse and use the same wing for both 

wing

Whoops! Sorry, the Airboat pic came in 

The fuse was done in 4 mm Corro, with 4 mm doublers in the front, and under the wing. Used a ply firewall (10 mm) and 2 of 4 mm formers

I used the old Avispad's tail feathers

The pic above was testing the wattage & Amp draw of the motor

At the field with Girish

A short clip. Apologies for the quality, it was a very hazy morning, and I was using a mobile phone

Needs a little down and right thrust

http://www.youtube.com/watch?v=QjeYMK1KpLg&feature=share&list=UUQhf5Pkzb8t7lzTwN0AIYEw

fantastic sanjay sir  i like your spirit  . and nice location too 

Thank you Nitinraj

I need some expert guidance here

On higher throttle (above 50%) the model climbs steeply, the higher the throttle, the steeper the climb.

Model weight is 1.15 Kg all-up. Semi-symmetrical wing of Span 51" (with elliptical wing tips) Chord 8.5" + 1.5" (aileron). Motor is 1180 KV developing maximum 290 W. Prop is 10*6 as recommended.

As far as I can make out the wing and tail are parallel, and the centre line is true. I have put 3 washers downthrust and 1 washer right thrust. There is no aileron droop. The CG is exactly on the spar, which is at 33% of the chord from the L.E.

The model flies perfectly up to half throttle, and can sustain level flight at 1/4 throttle. The glide is smooth and effortless even at zero throttle.

Where I am stymied is what to do if I want it to fly faster?

Is it an inherent characteristic of the model, with too much lift? Am I using the wrong prop?

Help and expert advice will be much appreciated.

wOW nice landing sir. when i will learn smooth landings like yours  .

This is the case of wing downwash hitting the tailplane, there is always a downwash from the wing (That why it lifts), however what happens as the speed increases is that the downwash starts to hit the tail plane and tail goes down and she starts to climb.

remedy
(a) easier solution, move the neutral point of the aileron high, meaning at neutral both aileron should be about 5 deg up, move this neutral point to see effects at various speeds , some will settle at may be 5 some will take upto 12 to 15 deg

(b) for the future, avoid low sitting tail (lower than the plane of the mainplane) else you could make the aerofoiled tail and invert the camber. meaning say you are using semi symmetrical put th flat portion facing up

i hope this helps

PS
please check the thrust lines while you are at it, from the picture seems perfect

Thanks so much Gusty sir. I will try this at once and report the progress

How come it doesn't happen to others who have built and flown Avispads? They all use the same plans and configuration

Swizera: that particular landing was done by Girish, as I was filming 

But the model has a very good glide, and that helps a lot while landing

Quote from: sanjayrai55 on September 15, 2013, 01:18:53 PM
How come it doesn't happen to others who have built and flown Avispads? They all use the same plans and configuration

longitudinal dihedral of all build need not be same, must be happening, because of higher throws fliers may be compensating

Had a similar problem.
Span 54", 3 sqft, 24oz (700gms), section like yours.
Same behaviour with 10x6 @8400 rpm, 220 watts, 830gms thrust, 146 w/lb.
Cured with 8x4 @11000 rpm, 96 watts, 480gms thrust, 64 w/lb.
Now flies even better by saving 100gms using 1000mah instead of 2200.

In addition to what Gusty sir says,
i suspect 116 w/lb too high for this section/decalage combo and
significant forward movement of CP with increase in AOA.
CG possibly too far back.
Request Gusty sir's opinion on correctness of this analysis.

Further, if nose up is under acceleration / at constant speed, thrust line passing too far below centre of mass / centre of drag. Aggrevated by excess thrust.
Try more down thrust if you don't want to go to a smaller dia/pitch.
Maybe even lowering the battery!

Changing prop changes propwash, it will definitely affect the downwash. this approach may too, no harm in trying it. o that end i do agree with Iyer sir

Thank you Iyer sir, Gusty Saheb. 

I have increased the aileron reflex to approx. 10~15 Deg.

I do have a wooden 9*5 prop, will try it. Also will try 10*5 or 1047.

Gusty Saheb; I have done something different from my earlier model, and the plan (which all follow.) Just remembered. I have stuck the horizontal stab to the bottom of the fuse, the plans call for a slot about 20 mm higher and the stab to be inserted there. Was just lazy I guess. I figure this will increase the 'leverage' or moment arm created by the downwash 

The increased Aileron reflex did not help. I will now try a 10*5 or 9*5 prop

Sanjay sir, one easy option I have found (if your transmitter supports) is to mix the throttle with the elevator. When the throttle has crossed 50% you can give a little down elevator to keep the plane horizontal. Of course would require bit trial and error to get the right mix setting.

Thanks Vishal. Yes, my Tx does permit, and that option is there.

It's just that I'm trying to get to the bottom of this . The model flies well, but I am not fully satisfied...........

Quote from: sanjayrai55 on September 15, 2013, 01:18:53 PM
How come it doesn't happen to others who have built and flown Avispads? They all use the same plans and configuration

It happens with all my trainers. As the throttle increases, the plane starts climbing rapidly instead of going fast.

I would be interested in the solution as well. I was under the impression that a given model can fly slow or fast according to it's character/airfoil - symmetrical airfoils fast, flat bottom slow (due to increased lift in the flat bottom wings, they'll naturally rise at high speeds)

Vishal, I guess you are correct. My own experience with trainers shows they don't like to fly too fast, and only climb (or descend) according to throttle. The increased span (from 48" to 51") probably increases this.

I guess I got spoilt by the earlier Avi, which flew real fast, and was super on basic aerobatics. You could fly it inverted the whole day