Piaggio P180 Avanti scratch build previously "Foam choice for a scratch build...

Wingnutz · February 26, 2014, 09:39:42 PM

Martin,
I am again impressed...this time by your honesty posting the maiden flight video! The good news is you've learned how to make it better while the model looks to be in pretty good shape and repairable!
Your flying field looks as bumpy as ours...no wonder your retracts had a hard time! I'm helping my club to install a geotex runway at our field this season so the scale models will have a smoother ride for take-offs and landings. Until that's done my Piaggio will be hand or bungee launched.
I am preparing for a family wedding next week and haven't found much time for my Piaggio. I will post when I have made some progress.
Best wishes for the next flight. Your Canadian fans will all be rooting for you and the Piaggio and cheering when you and the model have a successful flight

...keep us posted!

piker · February 27, 2014, 09:44:03 AM

Yes! Keep at it, Martin! Your Avanti looks SO nice, and I'm sure the next attempt will be successful. Great work!

Wildmieze · February 27, 2014, 04:27:51 PM

Thanks to all!

I will report on Sunday what happened. What a great forum! Thank you!

Wildmieze · March 02, 2014, 11:47:45 AM

2 Try and perhaps last: FAIL!

The Avanti rolled very nice and straight and also gently rose high, but then followed by a tilting movement, which was not to control. A gyro would have maybe done, but in the split second that was not possible absolutely. There was a rollover to the right and the impact on your back. Well ...
Landing gear bow and main) back out, front wing off, tail off, dent on the back, is cracked wing. Actually, no huge things, BUT IT ANNOYS ME! This stupid thing has to fly!

So far so bad. I have to go cry now first. : (

Here a short video from my attempt: https://www.youtube.com/watch?v=lkIabhGw4O0

sihinch · March 02, 2014, 01:21:23 PM

So sorry Martin. You have to keep at it because they say "third time lucky!"

Good luck with the repairs. Don't give up.

Frank v B · March 02, 2014, 08:24:41 PM

Martin,

I looked at the video about 10 times and here is what I suspect:
1) from the time the plane started the take-off roll to the time it passed where the photographer was standing, the "up" elevator was significant. (on a plane with the elevator up front, when the trailing edge down the effect is "Up"). It may have taken off prematurely.
2) the plane rotated (nose up) and then was corrected down. All the way along I doubt there was enough speed to lift off.
3) the plane first yawed to the left and was corrected but then over-corrected to the right. Some planes that wallow left and right (The Cub is notorious) are usually tail heavy. Double check the CG and correct to nose-heavy. A tail heavy airplane will wallow, a significantly nose heavy plane will not take off. So I always start off nose-heavy.
4) Increase the take-off speed. The biggest problem is that with two pusher motors in the back, there is no prop wash over the elevator and very little over the wings. I would try to keep the elevator neutral on take-off or even a little "down" to keep the nose down and get the take-off speed significantly higher than what you had when you took off. Speed= lift=control.
5) the grass was very bumpy. I would swallow my pride and put larger diameter wheels on the plane until after the first successful flight. If it has retracts, disable them. It will allow you to get a higher take-off speed and smooth out the ride.
6) I would put more exponential in the aileron or reduce the throw by about 20%. The correction to the right was very violent when there appeared to be marginal take-off/flight speed.

Correction: I notice from an earlier photo in the thread that the canard is fixed and not used as an elevator for pitch control. The opinion still stands because there is little prop wash over the tail and elevator. I would reduce the elevator throw by about 20% as well since it seemed to have more than enough authority in the video.
Why does it look like the canard has an "up" incidence to it in the video? Should it not be at 0 degrees?

For what it is worth.

I would love to read an evaluation of the video by Pat M.

Good luck.

Frank

Wingnutz · March 10, 2014, 06:41:59 PM

Quote from: Frank v B on March 02, 2014, 08:24:41 PM
Martin,

I looked at the video about 10 times and here is what

Correction: I notice from an earlier photo in the thread that the canard is fixed and not used as an elevator for pitch control. The opinion still stands because there is little prop wash over the tail and elevator. I would reduce the elevator throw by about 20% as well since it seemed to have more than enough authority in the video.
Why does it look like the canard has an "up" incidence to it in the video? Should it not be at 0 degrees?

For what it is worth.

I would love to read an evaluation of the video by Pat M.

Good luck.

Frank

Finally got time to watch Martin's second take-off...noble but sad effort...Martin, we feel your pain. We've all been there.
Frank, FWIW, in response to your #1 and correction above, I'm wondering if the full sized aircraft uses the front wing flap (inasmuch as it is only extended when the main wing flaps are extended) for take-off? Anyone know?
Also, on the full size aircraft, I think the front wing has a higher AofA than the main wing so the front wing stalls first and drops the nose causing the plane to accelerate back to safe speed.(assuming enough altitude!) My front wing is set with a few degrees more incidence than the main wing.
Martin's struggles have solidified my plan to build a small simple model of the Piaggio to try to establish CG in a practical rather than theoretical manner...but so far I'm pretty much all talk.
I haven't found much information on where people think the Piaggio's CG should be. Even if I do, I'm going to increase all three lifting surfaces and I'm guessing that is likely to move the CG anyway. Can't see a better way to get the CG located than a model of the model with everything proportional to the full-sized "model"

Bigstik · March 12, 2014, 02:12:19 PM

Hi Bill,

Noticed that you are using a magnetic build system. Are the sets available locally?

Bigstik

Wingnutz · March 19, 2014, 10:19:58 PM

Quote from: jabiggerstaff on March 12, 2014, 02:12:19 PM
Hi Bill,

Noticed that you are using a magnetic build system. Are the sets available locally?

Bigstik

Hi John,
Sorry for the slow reply. If the magnetic sets are available locally, I don't know where. I read up on the idea on a website called Airfield Models. The coated steel sheet, I bought locally at Metal Supermarket (if memory is accurate) in Scarborough, the wooden square corners I cut from particle board and I bought 100 magnets from the supplier mentioned on Airfield Models. I like the magnetic system but I still use a board and pins for a lot of stuff.

Bigstik · March 20, 2014, 08:28:32 PM

Thanks

Ededge2002 · March 20, 2014, 09:01:38 PM

Bill this project seems to have slowed a little so I'm going to post a photo of Canadian content inspiration for you!

Wingnutz · March 22, 2014, 03:44:40 PM

Ed, you couldn't have picked better inspiration!

For a number of reasons, the Piaggio project has essentially stopped but after three days battling a cold from the couch, I'm feeling ready to get back at it! Will post as I go.

Wildmieze · April 13, 2014, 06:40:19 AM

Here I am again!

I've noticed three errors: The propellers are too large. They swirl the air on the elevator so much so that the rudder can not grab. The control surface of the elevator is too small. The front wing does not bring sufficient effect, so that the fuselage does not lift. The C/G was now too far forward. 3cm from the front edge of the main wing is too much. Now I'll test it with 2cm.

Now the Piaggio has been repaired, eliminating the errors and now I wait up to perfect weather conditions.

Third attempt to start the Piaggio P-180 Avanti

Frank v B · April 13, 2014, 02:13:03 PM

Martin,

Go for it. Good luck in your next attempt. We are cheering for you.

Never give up!

Frank

Wingnutz · April 13, 2014, 08:16:42 PM

Martin,
I am in awe of your determination and energy! As Frank says, we are rooting for you and the Piaggio!!! Si bellisima!
When you have the CG right, please let us know...I think you're close to getting it perfect.
Do you know how much positive incidence the front wing has relative to the main wing?
Are the motors mounted to provide upthrust or downthrust?
I have paused my Piaggio project to re-plan, re-build and re-focus. Will let you know when I get back to it.
Good luck with the next flight!