Buffalo FX-79 Build - maiden/re-maiden crash, 3rd time lucky

[sykick]

Same motor as my FX61, I'm also on 3s but using a 10x7 or 10x8 APC prop....... It has plenty of go.

rgds,
Marcus

[Brod]

CoG to far forward? Not enough throttle? To heavy for power unit?
Elevon throw reversed?
Motor reversed?
Prop on backwards?
That throw was to steep.
Should have walked up that hill, or used a bungee.
Did you have any wind in the nose, that would have helped to.
Might have been better to try it line of sight with just the battery ,motor and esc before weighing it down with FPV gear.
Could have been any of the above really, at least it's fixable.
Just my thoughts.

all Jake says,fly it los first and always stand closish behind it on launch..

[UAV Aviation]

Feel sorry for you man  :( Such a nice plane. The only thing I can come up with is not enough up elevon. My experience with wings is that you need a little up elevon for launch, why...I don't know. It definitely  wasn't  a stall, 9 out of 10 they roll over and spin and it was to controlled. If you go to this link https://www.facebook.com/video.php?v=1469515149937951  you see me trying to Launch a Skywalker X-5, I am using a launcher and even with the high launch speed it just noses over, as controlled as it happened to you, luckily no damage but I was surprised as well. After looking at the images it was clear it was a controlled dive, so I went out again, trimmed up elevon and they're it went  https://www.facebook.com/video.php?v=1469521006604032  . For me this is how it works with wings also with my X-8.
http://youtu.be/UeFcSFkVD3o
I hope it will work for you to GOOD LUCK!

[mutley2]

Really sorry to see that bump, it went with a real thump!
From the vid and my experience with my Zephyr etc that looks like a lack of reflex, you had enough air-speed for that wing area and as it gains speed it dives harder, reflex IMo.
Chin-up fella.

[Flyboysee]

I think enough has been said already, and I think the concensus is that it was not a stall.

Wayne, I never liked the look of that slow fly style prop and to me it sounded horribly underpowered - that's just an observation.

Did you do any kind of range testing on the Dragon Link...? The input to down looked so positive I'm thinking it may have bean a total RC blackout... shit it's hard to tell. I also like Ian's and Steve idea on thurst angle & power etc. Either way, it could have been a combination.

Awful, sorry! FIX IT!

[benitoculito]

Dosen't look like a stall to me, the throw was fine, theres plenty of power in those 3s systems to get em up, i would check servo directions, auto pilot orientation and your mates javelin skills, get him ready for Rio ! The only time i had a nose diving incident with a wing was when i was experimenting with extreme hopping on my EZUHF, it happened 3 times during the test, a sudden loss of signal, was only flying line of sight over long grass and having not set a failsafe it just nosedived ! Having gone back to fixed frequency on the ezuhf i haven't had a problem, a bit off topic but hope you sort it out.

[CurryKitten]

Thanks for all the suggestions and observations so far - although there's a lot to consider, I will be doing the following.

1 - Fix plane.  In progress and almost done, nose is pretty ugly now but we'll try and smooth it out
2 - Test motor, if it feels weedy then perhaps it is.  Will test on watt/amp meter to feel how much it's putting out.  ESC is 40A I think, so you'd think it would get into the 30s at full throttle
3 - Range test DL, this has previously been out to 10km on FBS's penguin, so you'd think it would be ok, and RSSI was at 99% all the way into the ground, but a ground range test certainly won't hurt
4 - Trim the elevator up some more
5 - Sort out MFD display issues
6 - Find someone with very soft long grass and do a few LOS throw and glides before committing to a proper flight

[MarkLloyd]

Sorry about the maiden but it'll look as good as new with a bit of tlc !   

It put me in mind of my first launches with my Z2,  I didn't realise how much positive reflex was required in the standard setup which may or may not be a factor with yours.  I had several heavy nose ins that didn't do much for its looks.  Now with reflex sorted and plenty of power,  it gets  away every time no probs and it's fantastic  to fly,  I recon the 79 will be the same.  ( sorted the cosmetics after sorting the launches  :D)

With my funjet I've had some great flights, but the last 2 attempted launches nose ins...  being a bugger to launch,  I've learned to always launch it over an area of uncut long grass and undergrowth from last year which has saved it from any serious damage ( as you've suggested ).   I enjoy your vids so good luck  and I look forward to the one of your upcoming succesful maiden !

[Jake Bullit]

Made a great noise when it went in though. ;D ;)
I was suprised at how well the nose faired.The FX61 wouldn`t have come out as well as the nose is a bit more pointed,while the wider nose on the 79 probably spread the impact a bit better.

[Billy_boy_2010]

2 - Test motor, if it feels weedy then perhaps it is.  Will test on watt/amp meter to feel how much it's putting out.  ESC is 40A I think, so you'd think it would get into the 30s at full throttle

I really don't understand prop size, current draw, thrust values etc- so forgive me if I'm saying something you fully understand :D

but on a slow old wing of mine I used to run a 11 x 6 prop with a 4s. This maxed the 750kv motor out at 350W. It flew ok but cruised at 60% throttle on about 15-18A and I wanted something with more thrust.

I foolishly put a bigger prop on it- a 12 or 13 x 6 from memory- an online calculator said it would kick out 400W and an extra 400g of thrust- and it was a nightmare to launch. Several failed launches I just got it in the air - but it wasn't much good.

Anyway- I decided that the prop was so big the motor wasn't able to hit its max kv on launch- hence why it couldn't get in the air even after a big throw.

If a different member on here is running the same motor as you and using a much smaller prop it may be worth subjectively comparing the thrust to see if there's much difference?

I agree there more to it than just the motor output though.

[UAV Aviation]

Just a bit more up trim on the elevon, or reflex as they call it, and you will be fine  ;)

[Billy_boy_2010]

Any progress with this? A re maiden due any time soon?

[CurryKitten]

I was going to try and remaiden at the weekend, but I found that the carbon spar that runs through the main fuse was very slightly warped (after a rapair).  The carbon rods from the wings slot into this, but it also fits tightly into a ratainer in the wings which can be tightened.  Where it was warped it didn't go in properly.  So I Need to replace this - I'd assumed my repair was ok... duh.  As soon as I get this sorted, it's good to try again.

[Billy_boy_2010]

Ah bad luck.

Sounds like it was a fairly easy repair all in all.

Will keep an eye out for the remaiden

[rob.thomson]

Looks to me like you where to far forward on the cog, and not enough reflex.


IMHO, I would probably look to test glide it first over long grass.