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My first build - a (modified) MUTTS

Brett_N

Well-known member
#61
Be careful - Stik's are addicting.

In fact, I'm not sure why we ever really bothered to make any other planes. I have stiks for everythinig.

Big stik for dropping paratroopers and bombs (6s motor, 60" wing)
Mini Stick for playing with (3S, 32" wing)
Tiny Stick - just, why not, it's like 20" wing
Middle Stik - 42" wing for 4S
And the Slow Ride - because EVERYONE needs a 60" 3S capable 3D stik.

My next experiment is going to be trying to replicate the Slow Ride characteristics in Foam. Probably not as big, but a folded over KFm4 type wing should work on a MUTTS / TT fuse. Just started playing with KFM wing folding (Sorry Josh, not as pretty as yours, but much easier to fold.)
 

jross

Well-known member
#62
I crashed this morning after very little air time on one of my new builds, happens.
Yup. One of the reasons I generally don't doll up my planes. Just not there yet.


I'll need to do some repairs and strengthen a few sections in the nose, but it'll need to wait till next week.
You got it in the air, Dude! More than I can say for my first flight attempts.
 

jross

Well-known member
#63
Just started playing with KFM wing folding
Why bother folding? Just cut out the layers and glue them together. Check out this thread by @Hai-Lee. I used white glue to assemble and wouldn't suggest that. My wing tacoed upwards like mad. Checked it in 3 weeks and it had flattened out but by then, I'd built a second and just hot glued it. The KFM wing possibilities are wide ranging. I was amazed once I started researching.

https://forum.flitetest.com/index.php?threads/collaborators-build-1-800-mm-kfm-flying-wing.54085/
 

messyhead

Well-known member
#65
Ok, I'm confused about the expo. When I look at the graph, +30% looks right. It goes up slowly then increases. -30% it goes up quickly then smooths.

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Hai-Lee

Old and Bold RC PILOT
#66
Ok, I'm confused about the expo. When I look at the graph, +30% looks right. It goes up slowly then increases. -30% it goes up quickly then smooths.

View attachment 130205 View attachment 130206
You want the curve that is flattest in the centre.

My Flysky has the curve on the left when I use negative expo and the only reason I can think of as to why is that the firmware has been updated since I bought mine!

Just check to ensure that the servo moves slower in the centre after the expo is increased to 40%.

Have fun!
 

messyhead

Well-known member
#67
I had a look at the damage, and it's not too bad actually. The main concern is around the holes where the dowels were through, having become enlarged. Where the foam was double thickness, it's ok. But where it was single thickness, the holes have been damaged. The sides of the nose are a little crumpled, but are actually ok. The holes inside the power pod have been enlarged quite a bit, even though they were behind doubled FB. The only other damage was to the wing tips which folded, but are also in one piece. I think having it wrapped in tape has helped.

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mayan

Legendary member
#68
I have enforced power pods in the past but think that it’s not worth it, just build a new one. The reason why I stopped reinforcing them is because that helps with the shock that the motor would receive if reenforced.
 

messyhead

Well-known member
#69
As to how it got the damage, well it's not the best video as my son had the camera, but you can see how sharp the turns were at the start. It even looped just before crashing. Off camera, I cut the power and it glided quite nicely under control, then I was trying to turn it away from us, and it crashed. The battery alarm started sounding which was a distraction. I think I'd accidentally set the voltage alarm to be 3.6, instead of 3.3, so it went off straight away.

 

Hai-Lee

Old and Bold RC PILOT
#70
Somewhat minor damage to the fuselage. The quickest way to return the holes to original is to cut out a square around the hole. cut a new piece to the shape of the cutout and glue the new piece into the square hole. apply a tape patch over the new piece and make a new hole in the original position through the new patch piece. Sounds complicated but it actually quite simple.

You have not shown the wing tips but if not too bad they can be pulled back into as close to the original shape as is possible and iff really floppy can be reinforced with a BBQ skewer along the crease lines. What you add to one wing you must also add to the other wing!

DO not make a new anything but rather keep repairing until it is not possible any more and then make a new replacement!

Have fun!
 

Hai-Lee

Old and Bold RC PILOT
#71
As to how it got the damage, well it's not the best video as my son had the camera, but you can see how sharp the turns were at the start. It even looped just before crashing. Off camera, I cut the power and it glided quite nicely under control, then I was trying to turn it away from us, and it crashed. The battery alarm started sounding which was a distraction. I think I'd accidentally set the voltage alarm to be 3.6, instead of 3.3, so it went off straight away.

It actually had a good launch and flew quite well. So the build did not introduce any real issues. It actually looked sweet for about 15 to 20 seconds.

Repair, adjust the controls, (throws and Expo), and retry!

Have fun!
 

messyhead

Well-known member
#72
Thanks. I've changed the expo to 50% and rates on all controls to 50 as well, so hopefully that'll soften the controls enough.

I'll spend the next week doing repairs. I'm away next week, and I've also ordered a new battery, and some 9x5 props. So I'll wait till they arrive and can fully charge the batteries before trying again.

Thanks for the encouragement.
 

Hai-Lee

Old and Bold RC PILOT
#73
Thanks. I've changed the expo to 50% and rates on all controls to 50 as well, so hopefully that'll soften the controls enough.

I'll spend the next week doing repairs. I'm away next week, and I've also ordered a new battery, and some 9x5 props. So I'll wait till they arrive and can fully charge the batteries before trying again.

Thanks for the encouragement.
There is one thing you should know about wings generally! As long as the shape is close to right at the wing tips then it will fly because the closer to the tip you get the less lift it generates! Whilst you might think that the ailerons are quite powerful if you balance the plane along its centre line so that the wings are level and using small weights see how much force it takes to roll the plane. You will find that it requires very little weight actually and so very little force in flight. (This changes markedly when flying high speed aircraft though).

I have seen many videos where the plane crashed without ever attaining flight and some had crashed many planes before they managed as much airtime as you did on your very first attempt! Well done!

Have fun!
 

messyhead

Well-known member
#74
I have seen many videos where the plane crashed without ever attaining flight and some had crashed many planes before they managed as much airtime as you did on your very first attempt! Well done!
Thanks :)

How far back should the CG be from the wing LE? Is there a way to work it out, or should it be below the main spar?
 

Hai-Lee

Old and Bold RC PILOT
#75
Thanks :)

How far back should the CG be from the wing LE? Is there a way to work it out, or should it be below the main spar?
I worked out the CG by a rough calculation and then adjusted it by the way the plane actually balanced in flight.

The large tail and the short tail moment makes the balance point rather broad. I fly mine with the CG or balance point just behind the front wing spar, (the wing has 2 spars). It is easy to find because the first wing crease line is just in front of the front spar and so about 10 or so mm rearwards from the front crease line should be a good starting point. Always adjust the CG to your experiences because we rarely build exactly the same wings even though we use the same plans and some variation in the balance sweet spot may be expected, (but not much in fact).

When you get it flying again and you are able to trim it out for level flight look at the trimmed tail/elevator to see where it trims. If it trims slightly elevator up it may be too nose heavy and if it trims slightly elevator down it may be slightly tail heavy. This assumes that the plane flies quite well otherwise.

Have fun!
 

messyhead

Well-known member
#76
As to how it got the damage, well it's not the best video as my son had the camera, but you can see how sharp the turns were at the start. It even looped just before crashing. Off camera, I cut the power and it glided quite nicely under control, then I was trying to turn it away from us, and it crashed. The battery alarm started sounding which was a distraction. I think I'd accidentally set the voltage alarm to be 3.6, instead of 3.3, so it went off straight away.

I just watched this again on half speed, and it looks not bad actually :D
 

Brett_N

Well-known member
#77
Why bother folding? Just cut out the layers and glue them together. Check out this thread by @Hai-Lee.
With a KFM4 you get a cleaner leading edge with the "outers" being folded over the middle. If I was doing a KFM1 or 2, absolutely, just stack & glue. It's really not that hard - just add 1/2 inch to your "outers" measurement, score and cut 2x 45's and fold it over the leading edge. For example, if I'm doing a wing with a 10" chord, I'd cut 1 piece 10" x Wingspan for the inner and the second 20 1/2 x Wingspan for the "outers" - the 1/2 inch is taken up in the fold and gives a nice rounded LE. Since I'm aiming for more of a "3D stick" the KFM4 makes the most sense as it's symmetrical.

 

messyhead

Well-known member
#78
So the plane is rebuilt, and I used some reinforced tape around the peg holes to add some durability.

I checked the balance point, and it's pretty nose heavy. If I strap the battery underneath, just forward of the wing, then it balances with a slight nose down. So I'll need to add some weights to the fuselage further back. I'd prefer to have the battery in the nose for some protection.

Another concern is the prop centering. I got a collet type prop adapter, and no matter how I put it on, there's a wobble in the nose cone. I checked the motor shaft and it's straight, I took it out of the motor and rolled it on a flat surface to check. So it seems the prop adapter not going on straight. Is there any way to solve this? Is there a better type of adapter to use?
 

messyhead

Well-known member
#80
Does the prop go in all the way on the shaft straight?
On the adapter shaft? It's centred on the adapter. It seems like the adapter doesn't go on straight to the motor shaft. I've tried a few times to get it straight, but I also thought the clamp would self centre.