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Nail Biting...Maidened the HK FPV-168 this morning

#1
Sometimes forums can be like therapy, and I have something I need to talk about.

I've been flying sub 1lbs foamies for about 4 months now, and have crashed...a lot. Sure I read stuff about how important CG was. Wait, what is CG? ;) I learned about CG the hard (and dumb) way- Trial and error. Again and again I watched as almost every plane I built turned out to be tail heavy. Almost half the maidens I've flown have left the ground, immediately dropped the tail, gone straight up while I'm busy punching the throttle all the way forward trying to recover control, only for it to flip over, spin, stall, and otherwise hit the ground on every part other than the wheels or skid. (And don't get me started on how much I read about thrust angle...)

Fast forward a couple months- I bought the fiberglass HK FPV-168 v2. Fiberglass....balsa. For someone who can hot glue, tape, and BBQ skewer just about any deformed and mangled foam plane back into flying shape, those two words are already starting to make me sweat. Sure I'm handy and can work a #11 blade like nobodies business, but as I opened the FPV-168 box and started to pick through the parts, I knew I had taken perhaps too big a leap forward in my fledgling hobby. Sure, everything was there, you just have to put it together? I mean, the 'AR' in ARF means Almost Ready, right? Fast forward three weeks later, I'm stuffing lead bullets (just bullets, not a loaded cartridges!) into a ziplock bag and stuffing them into the nose of the plane trying to wrestle the CG just another inch forward. I'm measuring distances between wingtip and horizontal stabs to make sure I centered the main wing mount holes, and that the horiz stab is square, that the motor mount is centered. The biggest batteries I've ever owned are the 2200mha 3s turnigys I bought when I built my tricopter. (Which, side note- got me started in all this rc business, and something I haven't flown in 3 months) Now along with the lead, I have two 2200s in the nose...as far forward as they'll go. All this and I'm 1/2" behind the 'internet suggested' CG of 3 inches from the leading edge, and besides a boat anchor, I'm out of heavy objects to stick in the nose. Crap.

I'm starting to sweat again. I literally fall asleep picturing the plane, the 2 batteries, and all the lead in the nose rising up...straight up...and smashing nose first into the ground crushing fiberglass and balsa to little bits. Then I weigh the plane. AUW is...is....this cant be right....the scale says....5.5lbs. (2,5kg) The heaviest plane I've ever built was 1.1lbs. (0,5kg) I thought I was sweating before, now I'm soaking in it. Stewing in my own juices. How fast will this thing have to go to get off the ground? When it breaks the sound barrier on takeoff, will the wings just snap off? Will the landing gear collapse when I try to land? (HA! Landing? Only in my wildest fantasies would the plane be landing on the wheels!)

About two days ago, I began, in order to protect my fragile mind, to take a fatalistic view on the whole endeavour- "You know it's going to crash, stop worrying about it.", or "I hope most of the electronics will survive when this thing hits the ground at 40mph.", etc. Last night, I even took pictures of it so I could remember what it looked like, and all the work I had put into it. Ahh what fond memories those would be. Sigh. I woke up this morning, prepared for disaster. I had already written the plane off, and come to grips with it's loss. In fact, if I would have been slightly more awake at 5:30am this morning, I would have grabbed a couple of trash bags to make collecting the pieces easier.

I drove out early to the field in almost a daze. I wanted to be there early, so I would be the only witness to my walk of shame. I thought briefly of the inspection I did last night- Servos still tight, battery tray secured, servo connections all good, EZ connectors tight, motor mount tight, wheel collars tight, etc, etc, etc. I felt as if I had done everything I could...there was nothing left to check.

I arrived at the field, got the plane onto a pit table, and bolted the wing on. Crap! Is that too tight? Did I hear balsa crack? No wait, it's too loose! The wing is going to come off! Are the flight batteries charged? Is my transmitter charged? Did I bring my transmitter!? I got everything hooked together, and slowly checked each control surface, and made sure it was doing all the right stuff. At least when I crash, I know it wasn't because I didn't check my controls. I figured since I was the only one at the field, I would make some long runs down the runway to make sure the nose wheel was tracking straight, and that the prop and motor wasn't going to fly off the plane, and cut one of the wings off. Or the batteries weren't going to explode.

So I stand out at the end of the runway, and start giving it throttle...wow it's tracking straight...maybe a little more gas...wow good motor/prop choice, plenty of power...oh screw it, the suspense was killing me, so I hammered full throttle. And it flew.

Not straight up, not tail heavy, not smearing itself all over the runway in a massive fireball, but slightly pitched up , and lifted gently off the runway. I almost didn't believe it, but it happened. I managed two touch and goes, and no, the gear didn't crumple. In fact, the only part of the plane that touched the ground was the foam tire on each landing gear wheel. It flew, and it landed....twice.

I would love to hear from everyone recounting flying what they considered their first 'real' plane, or one that they had sunk a lot of time, money, or both into. I had just gotten over the nervousness of crashing foam planes, and then here it all comes again! But the best part is that when you are successful, there is a HUGE rush of satisfaction!!
 

colorex

Rotor Riot!
Mentor
#2
Great writeup! I have a desire to build a balsa plane (Extra 300S) for the nice feels and looks to it... But I haven't even printed the plans...

Congratulations on your success! How does it compare to flying foam stuff? Faster? smoother?
 
#3
Hey thanks colorex! Compared to foamies....its just different. I tried to keep it as slow as possible, and will continue to do so for the next few flights. There are so many fasteners going into thin fiberglass or balsa, I want to check everything after each flight. After 5 or 6 slow flights, when I'm sure everything is secured, I may try to push it a little faster. Also, I was so nervous through the flights, I don't even remember how much throttle it took for cruise. I also need to move the Nova OSD PA/RTH functions off the flap switch, and actually use it for the flaps. I had flaps on the little wheel on top the transmitter, and my hands were fumbling with it the whole time.

Also I need to get used to the diherdral- it took way more rudder than I'm used to for a nice turn. It's seems pretty stable, but need to fly it more and start to build confidence that's it's not going to disintegrate in flight and push the envelope a little more. While I'm super happy right now, there still is some dialing in to do!
 

lobstermash

Propaganda machine
Mentor
#4
Yeah, balsa is different. There's a saying that balsa flies better. It's mostly true. You get more of a feel that it's flying, rather than floating. I know it sounds funny, and maybe it's because there's less drag.

Still, pretty much all my planes are foam (though I'd like to replace a few with balsa models). They're great in their own way - there's so much more flexibility with how you set them up, and you can add and remove foam to make everything fit just so...
 

PaulT

New member
Mentor
#5
Treadd,
I have to say that the way you write had me believing that I was there with you.
If you're not a writer, you should be.
Nicely done on the flying too.
I feel your anxiety as It took me forever to fly my last scratch build seaplane for the first time on water.
One mistake and poof go the electronics.
Pictures please.
 

jd7792

Senior Member
#6
Nice write up! But I have to give you one word of advise - "Valium"
After reading your story I felt for you so much that I all I wanted to do was help.

All joking aside nice story, but would love to see the pics to put that final dimension to the thread!
 
#7
Thank you for the compliment PaulT! (unfortunately i do IT work...hmmm, maybe I could write IT manuals? :) )

And jd7792, hehe yea, I do need to calm down a little. I definitely do not get this way over the foamies at all. It was just the realization that if I crashed this, there would likely be no repair. Also, it took WAY more work to build than a foamie. :)

I flew it again today, MUCH less nervous, and even ended up dipping a wing during one landing, so its good it got its first little scuff. I will get some pictures up tonight!! I'll get some on board footage next week when the guy I borrow a GoPro from gets back from vacation. Cant wait!

Thanks again everyone!
 

jd7792

Senior Member
#8
Really glad to hear you are enjpying it. I love that whole balsa - fibreglass thing and am really looking forward to being there myself.
Congrats on the second successuful flight. What about a couple of snap shots?
 
#10
I dont have any video...I wish I did, but I'd have a hard time finding a camera man (friend) to wake up at 5:30am. Even with the promise of watching a possible train wreck! I do however have some pics to share!

2012-08-16 18.37.45.jpg

2012-08-16 18.37.58.jpg
Once I get my hands on the GoPro again, I'm going to cut the front part of the clear canopy and mount the camera as far forward as I can.

2012-08-16 18.40.01.jpg

2012-08-16 18.41.50.jpg

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2012-08-16 18.42.41.jpg
The Nova OSD reset button.

2012-08-16 18.43.51.jpg

2012-08-16 18.45.55.jpg
I weighed the bag of 5.56mm lead- 250g! This bag is stuffed ALL the way forward, ahead of the forward most nose bulkhead.

2012-08-16 18.46.34.jpg
From what I read online, getting the adjustable motor mount was a must if you wanted to run an 11 or 12 inch prop. Attached is a Masterscrew (clone from HK?) 11x5.5

2012-08-16 18.46.45.jpg
NOVA IR sensor towards the rear, and the GPS module between the blue tape.
 

colorex

Rotor Riot!
Mentor
#11
Awesome plane... Would you happen to know how it's built up? I would guess the FG halves are made first, then it's put over the plywood skeleton somehow...
 
#12
I believe you're right colorex. In fact the reason for the blue tape around the GPS module is when I cut the hole, the seam down the middle of the plane started to come apart. (You cant see the seam anywhere on the plane, but when I cut the hole it became obvious that it was two FG halves) I put some CA on the split, and then covered it up with the tape. If you look closely at some of the interior pics, you can see generous amounts of yellowed glue applied to where the wood frame attaches to the FG body.
 

Nelson S

Junior Member
#14
I am flying a Bixler 2 for FPV but footage with this plane is almost always bumpy. The advantage with this one is It is easy to hand launch and with flaperons+flaps it can land almost everywhere. Let me know how you do with the fiber one carrying FPV stuff.
 
#15
How weird is this. So the day Nelson S. posted (Wednesday) the inevitable happened. Dumb programming mistake on my part while trying to dial in a flap/elevator mix. Hit the flaps, WAY too much up elevator was mixed in, lovely FPV168 went straight up, nosed over, and ended up in a death spiral straight down into the unforgiving earth. :( I think there was about 2 seconds where I could have saved it, but in that crucial moment I thought looking at the screen would help me recover. By the time I looked down at the screen, it was in a vertical spin straight down. Ohhhh the sound it made.

The nose took the brunt of the force and folded up like an accordion. I broke one wing section off, and there is some strange stress cracks on the tail. Bottom line is the fuse is a total loss. I may try and repair the wing and stick it on something else. It was pretty disappointing to say the least. However, I learned A LOT, and got probably 70, non-crashing flights out of the plane.

LESSONS LEARNED-

1) DO NOT try to do a mix while the plane is on the runway. VISUALLY CONFIRM what the control surfaces are doing so you can spot any obvious mix problems.

2) It will be a looong time before I buy a fiberglass and/or balsa plane again.

3) Do what most guys do at the field and blame your radio or claim a brown out. ;) It's much less embarrassing.

Good news- All of the electronics survived! I have already transferred everything back into my original Experimental Airlines box fuse twin boom FPV plane. Man, its weird to say, but the twin boom is much more docile than the 168.

I'll post pics of the aftermath, as well as the FPV crash footage. I only watched it once- kinda gives me that sick feeling to watch it again, but hell, it makes for good internet video. I also pulled out my phones video camera as I was heading out to see the crater. In the back of my mind I thought, hey, what if the damage isnt so bad? That would make a great video! Then I saw how bad it was, and lets just say I would need to bleep out most of my verbal reaction.

Ah well, it was a fun experiment, but I think foam planes will be in my future for a while longer. I have plenty of hot glue and packing tape. :D
 
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