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Apr 05, 2017, 03:23 PM
RMRC
McSkies's Avatar
Since we are showing it off at the Weak Signals show in Toledo this week, we wanted to have a page to show information. As Zander said, we will open up for pre-order once they leave the factory. We don't like to tie up customer's money for too long when unexpected production delays are a very real possibility, not to mention clearing customs once in transit.
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Apr 05, 2017, 03:28 PM
Team Futaba / Team RMRC
Sukhoikid's Avatar
RMRC Goblin (2 min 2 sec)

Some raw video of the maiden flight of mine.
Apr 05, 2017, 03:29 PM
Team Futaba / Team RMRC
Sukhoikid's Avatar
RMRC Goblin Maiden (2 min 25 sec)

More raw video of the maiden
Apr 05, 2017, 03:36 PM
Team Futaba / Team RMRC
Sukhoikid's Avatar
I wouldn't mind trying a rudder on this plane. You could do some wicked maneuvers if it had rudder, but would add more drag and slow it down. I'll rig one up with rudder one day once the production model comes out.

This is a fun plane stock and highly suggest everyone to try to streamline all your FPV gear to get the best performance out of her!
Apr 05, 2017, 03:45 PM
ZEmersonFPV on YT
Quote:
Originally Posted by Daemon
One reason I know the fuse was pressurized, is by watching the indicated altitude value
change right at the instant that the elevon comes off (watch your vid frame by frame).
Despite still going down at a great rate, the altitude value actually jumps upward briefly.
A higher pressure indicates a lower altitude and lower pressure (when the nose swings
sideways relieving some of the pressure in the fuse) indicates a higher altitude.
You probably know this, but will explain for others.
The problem is the static port for airspeed measurement is there specifically to compensate
for altitude changes. Without a static port the indicated airspeed will keep increasing just by
dropping to a lower altitude (or decreasing as you go higher). The static port open to true
atmospheric pressure, cancels out the effects of altitude change, so the only
remaining pressure is from forward airspeed. Block, or pressurize the static port and
airspeed reads high. Sometimes very high.
Full scale planes often put the static port on the side of the plane (one on either side and average their pressures),
Flight controllers often share the static port with the altitude sensor inside the FC itself, so if the fuse
is pressurized (or at slight vacuum) then it messes up both the altitude reading and the airspeed.

Also if you figure 45mph starting speed, into a 6 sec vertical dive accelerating at 1G, that's
good for about 176mph. Your dive wasn't quite vertical, but did include higher throttle, but
it would take a ton of acceleration between 45-140mph (about where the prop pitches out)
to get that final speed over 200mph. To get from 45mph to 225mph with 1G vertical
dive with zero drag (or motor offsetting drag) would take a full 8.2 seconds.
Sound logic and math. But it's more fun to believe my cheap Chinese OSD so therefore, I reject your reality and substitute my own.

Weeeeeeeee!! That was fast!!!!!
Apr 05, 2017, 03:48 PM
Registered User
Daemon's Avatar
Quote:
Originally Posted by zanderman111
They are being produced now, which will take several weeks. Once they've been made, a preorder will open up while they are in transit to RMRC
Ah, ok. I misinterpreted the plan as announcement coming at same time as pre-orders and pre-orders dependent on shipping..
I didn't realize the pre-orders weren't available yet.
Apr 05, 2017, 04:13 PM
FPV Dealer,Getting People High
Johnnymeg's Avatar
Cool I'd like to see more about this model
Apr 05, 2017, 04:47 PM
Registered User
Daemon's Avatar
Here's an early LoS flight I did while still tuning.
RMRC Strix Goblin early LoS flight (16 min 0 sec)

Doppler speed measurements put some of those fast passes over 130mph.

Note final production models will have orange (sigh) fuses instead of uncolored or my preferred black.

Next I'll post up a vid of the wing construction (I don't know if they'll be shipped out with the wings pre-built or not) which is quite innovative.
[edit]RMRC's page says PNP, so assuming wing is built including servos.
Given what I've learned, I'd probably tweak the build myself a little bit so the wing's joiner rod sticks out a half inch or so to overlap
with the central joiner tube in the fuse to reduce a weak spot (stress riser).
Last edited by Daemon; Apr 05, 2017 at 04:53 PM.
Apr 05, 2017, 04:50 PM
Registered User
Daemon's Avatar
Speaking of colors. I use Krylon Fusion paint which is supposed to work well with plastics.
The plastic in this fuse shrugs it (and just about everything else) off fairly easily so I just
have to keep applying touch-up paint from time to time.
Apr 05, 2017, 04:57 PM
Registered User
Quote:
Originally Posted by Daemon
Fast ridge run. Averaging 90-95mph, pulling maybe 20A.
https://www.youtube.com/watch?v=GeSKQNlCcvE

Been running it with 4S 3300mAh pack and so far as big as 4S 4000. It really pays to get the CG optimized.
If it's nose heavy it'll fly, but doesn't glide very efficiently. If it's even a couple mm too far back, it's pitchy to the point of unflyable.
When it's perfect, it's close to neutral on pitch, and will glide for a long long time. This is true of *all* high performance planks (note my profile pic).
That is without a doubt the most beautiful ridge flight I have ever seen in my entire life. * wipes tear from eye *
Apr 05, 2017, 06:03 PM
Registered User
Daemon's Avatar
As I said above, looks like it's going to come as a PNP version but in case you can build a spare
wing or they ever offer a version you can build yourself (so you can install different servos for instance),
Here's a video showing how the wing goes together, and the rather clever internal construction.
Strix Goblin - Wing Assembly (14 min 1 sec)
Last edited by Daemon; Apr 05, 2017 at 06:14 PM.
Apr 05, 2017, 06:09 PM
Registered User
The size looks good. How well does the plastic fuz hold up after a few dings?
Apr 05, 2017, 06:51 PM
Registered User
Daemon's Avatar
Fuse holds up well. Mine's been roughed up a bit sliding over sharp rocks but no cuts or dents.
Kinda hard to compare it to any other plastic fuse on the market. Closest I can think of is
the Bob Martin Duralene fuselages of the late 80's, but nobody here will recognize that reference.
The rounded shape is inherently very strong as well.
Apr 05, 2017, 07:13 PM
Registered User
Unrelated: I wish some company would design a plane like this or the mini talon that is designed to hit exactly 250g with a 2s li-ion and a full size fpv cam.
/Off topic
I really want this plane! With li-ons it seems like it could hit some crazy range and fast.

Daemon have you had it for long? How do you like it for general tooling around compared to the sky Hunter I see in most of your videos?
Apr 05, 2017, 07:43 PM
Registered User
Daemon's Avatar
I've had one for about 3 months although I haven't been able to fly it as much as I'd like due
to either rain/snow or windy as hell weather.
It's a very different beast than the Skyhunter which has full pan and tilt, is
pretty easy and relaxing to fly and I run enough battery to run it for long time, or pretty hard.
It's like a big comfortable and moderately sporty SUV.
The Goblin is a sports bike by comparison. Smaller, more efficient, and super fast.
Have to keep the drag down to maintain those qualities so fixed forward flight/HD camera
view (first fixed wing FPV aircraft I've ever had that didn't at least have pan) so demands
more focus. Also have to think about my landing space a lot more.
Harder to match speed for chase/formation flying with anything else because even with
the motor off, it accelerates in a dive (had this problem with Graugans as well, which is
why there's more video *of* it than *from* it). At least now there's a chance of flying with
another Goblins. It is a small plane so it gets kicked around by the wind a bit more
than something the size/weight of the Skyhunter. With its small high revving prop,
it's noticeably louder at cruising speed than the Sky Hunter, although quieter compared
something like a Funjet or Stryker or Zephyr at equivalent speed.


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