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Pumpkin drop event

nnP-38 - design, build, and review log

rockyboy

Skill Collector
Mentor
It was awesome! A very solid plane, but with so much thrust it basically pulled right out of my hands!

Thanks wilmracer - that was lots of fun to help out with!
 

wilmracer

I build things that fly (sometimes)
Mentor
It was awesome! A very solid plane, but with so much thrust it basically pulled right out of my hands!

Thanks wilmracer - that was lots of fun to help out with!

No, Thank you! I was super gunshy about tossing her myself. It was a big help!

I'm uploading full videos for each of the first two flights. Both are relatively short so i didn't want to cut them down too much. I need to tweak my camcorder settings a bit. When the sky is grey like it was today it has some trouble with the auto focus. I think I've had some luck setting the focus to infinity but I need to check. there are several points where the focus is less than ideal, but you get the idea. And when she's in focus, wow she looks good up there :cool:
 
That thing looks so good!

What adjustments did it need from the first flight? Obviously the elivator but was the CG ok?
The lift on landing flaps looks crazy. Im not sure as my build is not that far but have the flaps enough clearance to land without catching?

All in all great looking plane.
 

wilmracer

I build things that fly (sometimes)
Mentor
That thing looks so good!

What adjustments did it need from the first flight? Obviously the elivator but was the CG ok?
The lift on landing flaps looks crazy. Im not sure as my build is not that far but have the flaps enough clearance to land without catching?

All in all great looking plane.
Thanks! and thanks again to Rockyboy! Look forward to flying with you again!

So, the CG was the big thing. I was nose heavy on the maiden and that made it a lot harder to fly. Moved the back back about 1.5" and it felt good. I have to knock out the honey-do list today but once that is done I plan to put her on the CG stand and measure exactly where it is. I'll also measure the throws and share those. I won't be able to fly again until at least next weekend but I'd like to get a few more flights in with the settings tweaked and see if I can dial in the flap/elevator mixing. I am feeling REALLY good about this one.
 
The Hyperbipe looks great Rockyboy! Cool paintjob!


So ive had progress on the nnP-38.

A few issues that i did not catch in time.

The Cockpit fuselage, I tried the layering method so far. But the method i used to glue them is a problem. Hot gluing large sheets like this together is a difficult process. The area to glue is so large the glue starts cooling by the time I layer on top so I'm left with gaps where the glue was too stiff. My advice to anyone using this method to not use hot glue. For this reason I just ordered a tin of UHU Por.
I will probably still keep the fuselage i created and fill the gaps with plaster. Will add weight but im sure this plane can handle it.

Second mistake was the second boom. I cut it out and only just after gluing did i realise i had made two right booms. I forgot to reverse the plans. :( Not the end of the world, i could cut the glue lines and flip the sides to get the correct sides. but for an equal quality boom i want to rebuild. Might be worth an additional note in the plans to prevent others from making the same mistake. Silly i know but with all the excitement of building i just did not think of it.

Some pics attached, bad quality due to crappy phone.
IMG_6776.JPG
IMG_6775.JPG
IMG_6774.JPG
 
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rockyboy

Skill Collector
Mentor
I don't want to sidetrack the thread too much, but while we were out there rockyboy maidened his Hyper Bipe :cool:
Thanks guys! This was my very first 3 cell plane/flight and I really liked it. As everyone keeps saying, bigger usually flies easier - it handled the wind way better than my Tiny Trainer. I added some bigger wheels to handle the runway better for next time, and am fixing the telemetry alarm programming so I can keep a better eye on voltage for the next time out.

Also, for anyone who is interested, the HyperBipe just went on sale at HobbyKing last week - $78us. Mine was a swap meet purchase with some reinforcing of the landing gear.
 
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So before reprinting plans glueing and cuttung a new fusalage i tried cutting the bad one first. Turns out its actually preatty easy to cut out the hot glue lines and reset it. So now have both booms complete and ready to go. :D

Unfortunatly I have now run into my next error. The tail plane/elevator does not seem to match in shape to the cutout in the rudder. My tailplane is symmetrical and the cutouts seem to suggest an airfoil should be present on the elevaitor. Where did i go wrong? Should the spar not be cut into the foam? Or the foam for the servos only be 50% removed?
I noticed something was not right when the lower half of the elevator did not match the upper half.
 

nerdnic

nerdnic.com
Mentor
kevinmce,

Great work so far! I'll note in the plans and build video about reversing the second boom. Also I will be recommending a glue other than hot glue for any layered areas. I used bob smith foam cure which is cheaper foam tac. Worked really well.

For the hstab, you're fine to leave as is if you want. Idea is to use a wood spar that's .25" square. This gets embedded into the lower panel and then you remove the paper from the top panel to form over it. Your servo will embed into the bottom later and partially into the top.
 
kevinmce,

Great work so far! I'll note in the plans and build video about reversing the second boom. Also I will be recommending a glue other than hot glue for any layered areas. I used bob smith foam cure which is cheaper foam tac. Worked really well.
i have always had good luck with rubber cement for multiple layers of foam
 
kevinmce,
For the hstab, you're fine to leave as is if you want. Idea is to use a wood spar that's .25" square. This gets embedded into the lower panel and then you remove the paper from the top panel to form over it. Your servo will embed into the bottom later and partially into the top.
So i agree it should be OK as is. But im seeing a possible further issue. not sure how you guys cut and assemble the rudder hinge?
Currently I have cut the rudder on the hinge(leaving the tabs). This means the rudder/vstab is now in three parts, the rudder and the upper and lower vstab. When i place the upper and lower vstab in the hstab they are difficult to get pushed together nicely to match the rudder. and the connecting part between the upper and lower rudder is quite small and fragile... i dont want to rely on it to hold the pressure of the upper/lower vstab separating. Any ideas?
 

nerdnic

nerdnic.com
Mentor
Can you post a picture? The idea for the rudder/vstab is that it stays as one piece. The plans have a 50% mark between the upper and lower rudder, this is to indicate the placement of reinforcement. I bent a landscape flag 45 degrees and placed it here. Then to install the vstab you fold back the bottom half and slowly wedge it in. It will fit with a little flex but the reinforcement keeps the rudder from damaging.
 
So it seems that maybe due to my incorrect build of the hstab/elevator the shape does not fit the cutout in the vstab. See the first pics.
IMG_6782.jpg IMG_6783.jpg
So what i might do is to just cut out the vstab to make room for the mismatch in shape.

Due to my build technique I dont have the paper/tape layer in the middle of the rudder to use as a hinge. Obviously we need to round the rudder and vstab to allow the moment. So I decided to save the messy 45* cutting i just used tape to tightly round the edges, then i thought why not go so far as to create a proper hinge with toothpics?(see next pics) I'm feeling that this should be strong enough with some additional plastic folded layer in there but i would prefer to rely on your wisdom to prevent any major ruder failure. :) IMG_6778.jpg IMG_6779.jpg IMG_6781.jpg
 

nerdnic

nerdnic.com
Mentor
So it seems that maybe due to my incorrect build of the hstab/elevator the shape does not fit the cutout in the vstab. See the first pics.
View attachment 65861 View attachment 65863
So what i might do is to just cut out the vstab to make room for the mismatch in shape.

Due to my build technique I dont have the paper/tape layer in the middle of the rudder to use as a hinge. Obviously we need to round the rudder and vstab to allow the moment. So I decided to save the messy 45* cutting i just used tape to tightly round the edges, then i thought why not go so far as to create a proper hinge with toothpics?(see next pics) I'm feeling that this should be strong enough with some additional plastic folded layer in there but i would prefer to rely on your wisdom to prevent any major ruder failure. :) View attachment 65858 View attachment 65859 View attachment 65860
I think this will work fine if you're using a plastic cut out for the toothpick to swivel through.