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Aug 19, 2019, 01:28 PM
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smackfpv's Avatar
Quote:
Originally Posted by notamedclosed
If you are up for a day mountain trip we should try and meet up sometime. Need to pick out a few spots to fly the other equipment too....long drive for only 3 batteries worth of flying, even bringing a charger it would be hard to get enough flying in. So I'd want to get some quad flying in too.
I would be for sure but it will not be until 2nd week in September. Have a look at some wings that have good battery capacity or even some twin motor planes if longer flying times is what you are looking for. I like the simplicity of wings but I think there is some neat benefits to twin motors.
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Aug 19, 2019, 01:45 PM
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Quote:
Originally Posted by smackfpv
I would be for sure but it will not be until 2nd week in September. Have a look at some wings that have good battery capacity or even some twin motor planes if longer flying times is what you are looking for. I like the simplicity of wings but I think there is some neat benefits to twin motors.
Probably won't be for this season...but as a winter project that's pretty much what I want to do. Probably a large twin.

I'd like to have a pan/tilt setup that can hoist both the GoPro 7 and FPV camera, lots of room for batteries, 900mhz RC, and 1.3/2.4 vtx. Maybe, go crazier and use something like the Eagle Tree Vector instead of iNav.

Maybe the Sonicmodell Binary but I'm not sure that's big enough. My Twin Dream is another option. I'd plan to build it with as much redundancy as I can muster. Even if it's not setup stock like that I'd split the elevator with separate servo's. If I stuck with iNav I'd consider making a single engine emergency mode which could limit max throttle power to prevent a single engine failure from putting the plane into a spin. One nice thing about open source is you can change things if you need.
Aug 19, 2019, 02:21 PM
fly by night
BCSaltchucker's Avatar
I don't think going to a twin adds any real safety benefit for electric RC planes. The motors and ESC are pretty reliable and not under stress hauling a big cruiser like that around. I never hear much of wings blowing up motors, unless it is due to lousy spec choices, overpropping etc. However the twins do deliver the benefit of tractor power while not obstructing the nose.

I have given up on large FPV planes because of the busy airspace here. But I enjoy Arxangel and BonafidePirate's videos flying such big bruisers around long range. I miss the windy day performance of my old Z2 wing (though I do still have the Goblin, which is big by my standards, small compared to these 2-2.5m planes)

I kinda feel the weaker link would be iNav itself, compared to some of the pricier flight controller systems. I love iNav, and use it exclusively with planes having ditched all the others. But it is still just experimental/open source and has cost a few people their planes.
Last edited by BCSaltchucker; Aug 19, 2019 at 02:26 PM.
Aug 19, 2019, 03:05 PM
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smackfpv's Avatar
My bigger wings are simple stable flyers with basic autopilots for some display and RTH. Chimera fits this criteria for me perfectly. Tough as heck and field launchable. Still does 130 k, flies for 40 min and if I crash it bad, it wont break the bank. The Crash Test Hobby wings have also proven themselves with my fumble thumbs.

I like the idea of a twin just for the ability to maneuver and improved efficiency. I would consider a twin puller on a medium size wing, keeping the weight down so hand launching is practicable.
Aug 19, 2019, 03:08 PM
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smackfpv's Avatar
Quote:
Originally Posted by randy preece
https://youtu.be/DpHXLdb3Gsw
This is my planes twin the 2 of us have had a lot of fun flying them.
it was really windy still did ok and tuff as hell
Good vid Randy!
These are such fun little wings to mess with and great to fly and chase with a buddy.
Aug 19, 2019, 10:27 PM
fly by night
BCSaltchucker's Avatar
Quote:
Originally Posted by smackfpv
My bigger wings are simple stable flyers with basic autopilots for some display and RTH. Chimera fits this criteria for me perfectly. Tough as heck and field launchable. Still does 130 k, flies for 40 min and if I crash it bad, it wont break the bank. The Crash Test Hobby wings have also proven themselves with my fumble thumbs.

I like the idea of a twin just for the ability to maneuver and improved efficiency. I would consider a twin puller on a medium size wing, keeping the weight down so hand launching is practicable.
Wouldn't a twin be less efficient though? I thought efficiency comes from having larger lower Kv motors, pushing bigger slow carefully shaped propellers. Twin has to carry 2 ESC, and each motor is smaller than a single on same size plane, pushing a smaller prop and higher RPM.

https://www.rcgroups.com/forums/show...r-single-motor

Tractors are great for lift on launching while pushers are often less efficient just because of the dirtiness of the air coming into them. But that can be mitigated with thin trailing edges and thin overall profiles like the nanogoblin and big goblin. Those two are a pair of the most efficient FPV planes available today. Big Goblin to be avoided for ease of launch and crash rapair though.
Aug 19, 2019, 10:36 PM
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Quote:
Originally Posted by BCSaltchucker
I don't think going to a twin adds any real safety benefit for electric RC planes. The motors and ESC are pretty reliable and not under stress hauling a big cruiser like that around. I never hear much of wings blowing up motors, unless it is due to lousy spec choices, overpropping etc. However the twins do deliver the benefit of tractor power while not obstructing the nose.

I have given up on large FPV planes because of the busy airspace here. But I enjoy Arxangel and BonafidePirate's videos flying such big bruisers around long range. I miss the windy day performance of my old Z2 wing (though I do still have the Goblin, which is big by my standards, small compared to these 2-2.5m planes)

I kinda feel the weaker link would be iNav itself, compared to some of the pricier flight controller systems. I love iNav, and use it exclusively with planes having ditched all the others. But it is still just experimental/open source and has cost a few people their planes.
You can blame my profession, but I really do like the idea of adding redundancy whenever possible if I'm going to try a long range cruiser.

I can't find it right now but I'm pretty sure the coFPV guys had exactly that, a motor failure in one of their birds (Drak or Chimera) and actually ended up in a lake which led to quite a rescue.

A wing is problematic because a single servo/linkage failure can bring you down, but you can solve that by splitting the elevon. However, if we are talking about a twin then the wing isn't great because there is no rudder to counteract the asymmetric thrust situation. Vmca would be extremely high.

As long as the plane has a tail (and thus decent rudder authority) and you either A. don't overpower it, or B. have a method for reducing max power you should be able to get to the point where you won't get into an asymmetric thrust spin but be able to bring it home after engine failure. I haven't poked into iNav that far but theoretically you could create a sliding throttle limiter that incorporated speed and Vmca together to scale the max throttle as the aircraft speed increases. The advantages of open source. Thats', of course, if you go that route. I'm probably more likely to try an Eagle Tree system.

Asymmetric spin done on purpose:


I may consider designing my own...depending on how well the Sub250 build flies .

Speaking of, here she is painted up and getting ready for final electronics install. I tried laminate on this foam for the first time (used many times on EPP of course) and to my great joy it did a great job adhering to, and not melting, the foam. The leading edge is really solid now. I'll probably treat the nose/belly as well. Still on track for well under 250 with a 3S 650mah and still looking possible with a 4S 650. Depending on how it flies and the CG shakes out I think my final flight battery will be something like a 3S 850mah.

Last edited by notamedclosed; Aug 20, 2019 at 12:22 AM.
Aug 19, 2019, 11:00 PM
fly by night
BCSaltchucker's Avatar
that is a pretty bird! nice job

went out flying again tonight. I think the 7 inch quad will be OK, though I calibrated the amps sensor backwards, it is reading 700 amps at hover lol. Flew . minutes and used 900mah, so not bad. I might just live with these mediocre/poor lipos and kill them doing distance flights, hopefully not lose the quad. But man it's too bad the nanogoblin makes shaky video cause it is so carefree cruising around for a couple kms out, living the dream (dream being a cruising long range plane that replaces renting Cessnas for an hour)
Aug 20, 2019, 11:01 AM
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smackfpv's Avatar
Quote:
Originally Posted by BCSaltchucker
that is a pretty bird! nice job

went out flying again tonight. I think the 7 inch quad will be OK, though I calibrated the amps sensor backwards, it is reading 700 amps at hover lol. Flew . minutes and used 900mah, so not bad. I might just live with these mediocre/poor lipos and kill them doing distance flights, hopefully not lose the quad. But man it's too bad the nanogoblin makes shaky video cause it is so carefree cruising around for a couple kms out, living the dream (dream being a cruising long range plane that replaces renting Cessnas for an hour)
It is a damn fine looking machine for sure!

BC, did you do some more tuning on the 7 incher? I have the AK tune but I think maybe the P is a little high causing oscillations. Have you made any changes? I am working and quad is at home so looking an easy button solution.
Aug 20, 2019, 11:03 AM
fly by night
BCSaltchucker's Avatar
I have had servos fail on me, but I don't quite understand how one can make servos redundant. If a servo fails in flight, for example jumps a gear or seizes up, wouldn't it be fighting against the 2nd servo and still result in a crash? Or do you double up the servos so the stress on any one servo is greatly reduced? In that case why not just go for a heavier single servo? Though I have heard of doubled up servos on 1/4 scale and larger models.

Flying buddy of mine is ditching the R9 system. He's had one complete failure of a R9mini receiver resulting crash. And another receiver with unexplained failsafes. Though he has been flying his nanogoblin to 5km out and back.
Solution: Crossfire.
Aug 20, 2019, 11:05 AM
fly by night
BCSaltchucker's Avatar
Quote:
Originally Posted by smackfpv
It is a damn fine looking machine for sure!

BC, did you do some more tuning on the 7 incher? I have the AK tune but I think maybe the P is a little high causing oscillations. Have you made any changes? I am working and quad is at home so looking an easy button solution.
I agree, AK's tune is still too shaky for HD video. However I think I have to put some time into balancing the props before turning to PID tuning.
Aug 20, 2019, 11:28 AM
Registered User
Ok...I realize I just went on a rant about using a twin for reliability, split elevator, etc. However, after more reading and running numbers I think it's just not worth it. Something like the MTD is just going to cost too much to outfit. It's 230 just for the kit. GoPro 7 is down to like $440 now also.

Rotorgeeks has the 1800mm SonicModell Skyhunter PNP for $256.

Then something like the Furious FPV 2.4hgz combo.

https://www.banggood.com/FuriousFPV-...r_warehouse=CN

Eventually upgrade to the R9 Lite Pro for 1W @ 900 mhz and I think I would have the range I want. Enough for mountain surfing anyway. I do long range FPV for a living so that 60km round trip nonsense doesn't interest me. However, being able to takeoff where the park rangers can't yell at me...fly to the mountains and be able to spend 20 minutes just buzzing and diving around the peaks sounds like a lot of fun.
Aug 20, 2019, 12:27 PM
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smackfpv's Avatar
Quote:
Originally Posted by BCSaltchucker
I agree, AK's tune is still too shaky for HD video. However I think I have to put some time into balancing the props before turning to PID tuning.
This article speaks to what I was thinking.
https://quadmeup.com/detecting-clean...gain/#more-354

and this one speaks to current Betaflight tuning
https://quadmeup.com/betaflight-4-0-...n-7-inch-quad/
Aug 20, 2019, 04:13 PM
Registered User
Quote:
Originally Posted by BCSaltchucker
I have had servos fail on me, but I don't quite understand how one can make servos redundant. If a servo fails in flight, for example jumps a gear or seizes up, wouldn't it be fighting against the 2nd servo and still result in a crash? Or do you double up the servos so the stress on any one servo is greatly reduced? In that case why not just go for a heavier single servo? Though I have heard of doubled up servos on 1/4 scale and larger models.

Flying buddy of mine is ditching the R9 system. He's had one complete failure of a R9mini receiver resulting crash. And another receiver with unexplained failsafes. Though he has been flying his nanogoblin to 5km out and back.
Solution: Crossfire.
Depends on the failure of course. For it to work you need a split surface. So, the easy example is the ailerons since those are already split. If one aileron fails it will hopefully freeze in one spot that is somewhere other then full deflection, or fail to trailing (unpowered) which is what I've had happen to me. Even if it freezes in the worst possible position the other aileron should be able to counter it. That means you can't roll, but if you have a rudder you can use that to sloppily control roll, especially if you have any self righting built in like dihedral or keel effect.

What you want then for redundancy is a split elevator. This is actually common on all the bigger gassers I see out at the club. Two servo's, two independent surfaces. It's also very common in most commercial airplanes like the one that I fly. I have an emergency disconnect which will split the control for the elevator, ailerons, and roll spoilers. If I pull that disconnect then the captain side controls left elevator and ailerons, copilot controls right elevator and roll spoilers. Then once we identify which surface is jammed we can reconnect the "good" system back together.

R9....sigh....I just upgraded my Hawk5 and iH3 to R9....and was so happy with them. Today I was flying down the side of river and my quad started acting like it was drunk even though I was not far. Managed to crash land into the banks so no damage. It's been so good on my 2 wings though. Since I upgraded my antenna to the TrueRC one. Made it 3 miles on my little 100mw R9 Lite. The mountain flight I was over 2 miles out still great RSSI.

I don't know what to do about it. The price upgrade for Crossfire is certainly worth it if R9 loses your entire quad. My buddy put his new R9 6" quad into a lake with a brand spanking new GoPro 7 Black. Total loss...couldn't find it despite trying dredging, fishing line magnet, hip waders and finally snorkel gear. He also went to crossfire.
Aug 20, 2019, 04:45 PM
fly by night
BCSaltchucker's Avatar
ouch Gopro 7 loss scares me and shocks me! Love love love the videos it makes, but I could only use it on a quad, and could not stand the idea of losing it. So I dont have one yet. Just starting to use the Firefly 2, and so far not amazed, but the size and price is very nice (expendable)

Only thing I don't like about Crossfire is the size of the module, since I use an XLite mostly. I guess the cost of the receivers is nasty too, and I'd need at least 4 or 5 of them.

I still have not lost signal even for a moment with R9 yet. But I believe the stories out of failures. Combine that with the ACCESS fiasco and makes me think twice. I worry about the weak ufl connection for the antennas with all of these receivers. Wish they'd all go to MMCX
Last edited by BCSaltchucker; Aug 20, 2019 at 05:13 PM.


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