Restoration of a 40 year old mystere 3000 canard

[JFandL]

Test flight was bad, I mean very Bad. 10 seconds maybe of crashing. Tail heavy for sure and not much to do but cut power and watch it come back to earth. I've took today to look over the set of plans and I talked to Art after the crash at the field so I'm working out the C.G. again. Started the repairs today as well not really a lot wrong. Just some time and I'll give this one a go again. Crossing fingers that I find the right C.G. Back to work!

[rifleman_btx]

Awe bummer, I feel you will get it going soon. The different planes like this and my n9mb project are some tough nuts to crack.

[JFandL]

Well I know that the C.G. Art said he used on the plans is wrong, now by how much is the question. and I flew this aircraft before. off to work

[Hardway]

Well I know that the C.G. Art said he used on the plans is wrong, now by how much is the question. and I flew this aircraft before. off to work

Wow.... That is heartbreaking.... However, it is not a bag of sticks, so that is the good news... I am with you in spirit there, so find the CG and go again!!! :(:Cool:

[JFandL]

LOL, Yes onwards and I hope upwards and in the right direction this time. Installing new wood and I should have it together by tomorrow, then glassing, priming.. duct tape.

ugh!!

[fhhuber]

Basic Canard CG:

Find 30% MAC of the fore-plane and main-plane and the distance between.

Us the High School balance beam calculation using the areas as the "weights" to find where on that beam (distance between fore-plane and main-plane 30% macs) the CG belongs.

https://www.engineersedge.com/calcul...e_levers_1.htm (you know W {fore-plane area} and F {main-plane area}... solve for X)

Some balance on the LE of the main wing. Some ahead of it and some as far back as 15% MAC of the main wing. Never behind 15% MAC of the main wing. (if the calc says further back, its a stabilized flying wing or the fore-plane is too small to be useful)

[Hardway]

Basic Canard CG:

Find 30% MAC of the fore-plane and main-plane and the distance between.

Us the High School balance beam calculation using the areas as the "weights" to find where on that beam (distance between fore-plane and main-plane 30% macs) the CG belongs.

https://www.engineersedge.com/calcul...e_levers_1.htm (you know W {fore-plane area} and F {main-plane area}... solve for X)

Some balance on the LE of the main wing. Some ahead of it and some as far back as 15% MAC of the main wing. Never behind 15% MAC of the main wing. (if the calc says further back, its a stabilized flying wing or the fore-plane is too small to be useful)

Good stuff!!! Thanks FHH

[rifleman_btx]

Indeed, very useful information!:Cool:

[fhhuber]

Corrected the CG of the ancient Electricfly Wright Flyer using that calculation. Quite an improvement. Mine still flys.

[JFandL]

Yes that is some good info, I've read a lot of the canard C.G. calc. but this is not a b

asic canard CG: has as much as 3 times the area in front stab, front stab is also 2 deg. off from side to side. The model also has built in washout of 2 inches on the wing tips only and the ailerons don't follow the washout. This is a as I built it and not even what some of the plans called for. Plans called for 4.1/2 inches in front of the main wing root and that is tail

heavy. I'm sure if I move it forward 1/2 inch to 3/4 inch it will fly. But I'm still working on the C.G. slowly before I do anything with it.

[rifleman_btx]

I would go with 3/4" just to error on the side of safety. Can always move it back from there, but atleast there you wont have that much of a chance of this happening again

[JFandL]

Yes but like fhhuber said, getting a canard C.G. right on makes for the best flying airframe. The C.G. to me didn't look right to began with. I was questioning it from the start. I think Art may have did the C.G. without the plans and forgot about it. Like I said I've flown this aircraft before when it was flying. It flew very well. If I turn out to be too dumb to figure this out I'll go 3/4" cross my finger and call out a hail marry!:Silly:

[rifleman_btx]

Yeah it did look way tail heavy though, like my first attempted flight on my first n9mb try. It did essentially the same thing as this. But I was lucky as it went right back onto the gear.. it was almost 1.5 inches off the mark. But I dont truly feel you are THAT far off as I was. If I were a betting man I would say 3/4 to 1 inch in comparison. Just by way of what I seen in the video.

[JFandL]

Replaced the wood that needed it, sanded to shape and I'm ready to rejoin the stab back in place. Just making sure( check double check) before gluing. sheeting will be replaced once the stab is dried.

[rifleman_btx]

Sweet:Cool:, did you figure out what you need for the cg?

[JFandL]

Nope, I'm going to fix the airframe get it ready to fly and only then will I start on the C.G. I spent some 2 days making the C.G. numbers that didn't work. Canards C.G. is a little more tricky than other airframes. Its on my to do list before this weekend I hope.

[rifleman_btx]

Yeah, as I was saying earlier, if it's not giving you that warm fuzzy, dont chance it. Hopefully itll get there and we see a beautiful flight.

[fhhuber]

Make a cheap foam chuck glider the same dimensions (really rough airfoil is fine... flat plate will work.) and test that for CG.

Experiment with the canard incidence, you'll find appx +3 deg vs main wing is correct.

When CG is correct, but excess incidence on the foreplane, the stall will just drop the nose and it will keep flying straight forward.

Since correct CG depends 90% + just on the planform of the fore-plane and main-plane and the distance between them, you can trust the CG you get with this method.

Then you have the thrustline effects... but with a tractor (prop in the nose) and thrust line reasonably straight it will be controllable though it might exhibit some pitch and /or turn with changes in power.

You can fly a plane with a REALLY bad thrust line. I got a mis-assembled PNF model with thrust line 12 deg wrong and could trim it for hands off straight and level at 75% power.

[Hardway]

That is the truth!! I had a guy that I was helping and he had a scratch built pizza..... LOL A modified Round-to-It. His thrust line was so absolutely whacked out, I was scared to fly it... Anyway, a lot of trim and some pucker factor and it flew fine... He had glued on all the topping for the "pizza" and then varnished over it with fuel-proof dope... Just too cool... Wish I had a picture!!! I may make one in electric and use my daughter's construction paper...:Confused::Silly:

[Hardway]

[QUOTE=fhhuber;n144776]Make a cheap foam chuck glider the same dimensions (really rough airfoil is fine... flat plate will work.) and test that for CG.

Good call on that! It will save a lot of grief and glue..... :Cool: