ZOHD Drift CG Death Spiral Issue Solved
ฝัง
- เผยแพร่เมื่อ 11 ก.ค. 2024
- On the maiden flight of the ZOHD Drift, the Kopilot Lite did a great job with launch assist and getting the plane flying. As soon as I went into manual mode though--death spiral. RTH was able to save the plane two times, but on the third attempt to fly manually, even the Kopilot was unsuccessful keeping the plane in the air.
The initial setup used the factory molded CG markers for balance. Sadly, those are too far back for stable flight. In this video, my adjustment to CG puts it at the perfect spot for straight and level cruising with no bad handling issues.
ZOHD Drift Affiliate Link
► ZOHD Drift www.banggood.com/custlink/GGD...
RCVR CHANNEL LINKS
► Support the work I do here on Patreon: / rcvideoreviews
► RC Video Reviews Website: rcvideoreviews.com
► Discord - Hang out with the RCVR Crew: / discord
► RC Pilot T-Shirts! teespring.com/stores/rcvideor...
AFFILIATE LINKS
► Amazon Affiliate: amzn.to/3lEz5ZL
► Banggood Affiliate: www.banggood.com/custlink/3DD... - วิทยาศาสตร์และเทคโนโลยี
Thank you so much for posting this. I had the same problem - it would immediately dive and spiral to the ground as soon as manual mode was selected.
Since it was immediately going nose down, I wondered if it could possibly be nose heavy - but that makes no sense because the indicators I was using are already at about 50% chord.
So glad to hear it flies better with CG where one would expect - forward of those bumps. I've now seen other videos reporting the same. Even putting the CG just ahead of the bumps, at the front edge of the bumps, is reported to be a significant improvement.
After making the adjustment, it flies great. Did you try it?
Great video, and good Gouge 👍!
Thanks. With a tiny little adjustment, this plane turned into a winner.
older video but very important ! I just got a drift and would of destroyed it probably if I did not see this video ! God is watching over me this month ! thanks you. Keep the servo rods tight ! lol
Right on!
I just maidened the plane. RTH flew perfect. Like on rails. Balanced and manual was hell. Thank you for the heads up. Oh, and the VC400: Don't even bother to go above 25mW. It will burn itself to death.
When it's flying right, it's an awesome little plane. Glad your maiden went well. Have a great time with it!
I prefer the analogue capture if it means OSD info. :) Nice flight!
The camera has been replaced and I have an Immersion Powerplay on the way. That should yield decent OSD footage finally.
I lost my drift in a spiral death dive when in return to home mode this week. I had done the maiden flight in manual mode with no problem then I thought I would try a launch assist take off which it did perfectly then spiralled in on the return to home leg. It was so far away from me that I couldn't find the wreckage. Now I know to move the C of G forward it is a big relief as despite being a full size pilot I couldn't fathom out what I had just witnessed. I have ordered 2 more Drifts one kit and one p+p and will try again. When it was in manual mode it flew perfectly.
I'm also a licensed pilot, so I struggled with this too especially given in stabilize mode the plane flew fine, although if I'm being honest, it was not able to recover on the third attempt at manual mode on the maiden and the plane did crash.
Let's evaluate the information in front of us:
Here are the facts:
1) It's not a weight issue. There is plenty of wing area to carry the plane and contents.
2) It's not an aerodynamic/lift generation issue. In both of my scenarios, the plane flew with the stabilizer like a little bird. So we know the plane flies. Yours flew, mine flew, others fly.
3) The plane exhibits a tendency to spiral under some set of circumstances. I've seen first hand, and I've witnessed reports and seen other video evidence of the issue.
4) The stabilizer can manage it in some cases, but not others.
5) The book warns to not exceed 31mph/50km/h. Pawel attributed his spiral crash to exceeding this speed and generating wing flex which manifested itself in a death spiral.
6) I made very specific mention of wingtip flex in my first look video th-cam.com/video/ezeAZKRi-ds/w-d-xo.html before I ever flew the plane.
Assumptions:
1) Let's assume the people flying these things understand what a CG marker is and how to balance a plane to use the factory CG marker.
2) Let's assume people know not to turn this little plane into a bowling ball excessive equipment.
Here are the variables:
1) Wingtips flex
2) Manufacturer warns against speeds greater than 30mph
3) Balance on factory marks appears aggressive and the MAC calculation does not conclude with those marks. 25-33% of the chord for conventional airframes is conventional wisdom and the MAC calculation places it in that range.
If we accept the truths and examine the variables, we can zero in on the answer. I already know what I think. I'm interested to hear what others think given this summarized collection of information.
I'd be interested in the slow flight stall characteristics in manual mode with the new flyable CG.
Will it tip stall to the left or be gentle.
G-R-E-A-T question ;) I will definitely check that out next time I'm out. Given the comments, I will probably also try slowly moving that CG back to see what happens. I'm just glad it flies now.
The stall is perfect, a gentle level nose drop... nose down elevator to gain airspeed and back in biz...
This is an awesome little plane when the balance is right. I liked it so much I gave it to one of my long-time channel subscribers and patrons as a gift to enjoy.
Did yours come with a the tail twisted slightly? Mine flies well in manual / acro but when it is in stabilized mode it wants to bank left
It did. I released the binding ring and re-indexed it so the vertical stabilizer stands straight up. I did it by using locking pliers around the tail boom and set the grip enough to clear the shaft, but not the locking ring. Then I gradually tapped on the locking pliers to release the glue and move the ring. It didn't take much and I got it loose.
This was interesting to me because I found the Drift to work well with the stock CG points. I'm using a 3s 850mah battery, Kopilot and VC400. I'm curious as to what size battery you are using. Wondering if that choice is moving the CG point.
On the maiden I enabled manual mode three times. All three times the plane went out of control. Twice RTH saved it. The third time is the OSD footage in this video. For the maiden, CG was dead-on the factory markers.
@@RCVideoReviews I wasn't challenging what you saw. The video is convincing. I was just wondering if the battery size may have contributed to the issue, since I didn't have an issue. FWIW I did find that getting a good manual trim was important for manual mode as well.
@@richardjohnson2331 Again not disputing how this 1 reacted but we also started off on our maiden last weekend with the CoG at the normal 1/3 and no way we could get a decent unpowered glide or launch in Stabilized. (Manual is only for the very rare high altitude adventure with us doddering Old Farts!) Put it back on those very wrong looking marks and away she goes. Same for the Dart250. (Both on Kopilot.)
Strange things happen. A lot of very respected reviewers had trouble with the Volantex Ranger 750. Mine flew quite happily out of the box for quite some time - until rough landings and encounters with the local arboreal obstacles rendered some repairs necessary. ;-)
Oh I know, I get it. I was just reporting the details. The battery size is immaterial if the CG is achieved and isn't grossly overweight. The CG was dead on, and that same battery pack flew it successfully on the 2nd flight--so it wasn't a weight issue. I would have happily trimmed the plane if it didn't immediately try to crash. I can fly a stable but out of trim plane though and it turns out with the CG forward, I didn't use any trim. It flew straight.
I have other comments on the Livestream where I first showed this issue reporting the same exact problem. Another TH-cam showed video of the same problem but he attributed his to wing flex and speed. I didn't have an OSD on, so I don't know how fast I was going, but I know it wasn't full throttle.
I fly mine without any FC, using the same 3s 850mah lipo, and stock CG. It flies great. When adjusting the CG, I make sure the tailboom is horizontal.
glad its fixed
Yeah, I flew it today for a long time. Not a whole lot of it in manual mode, but manual mode is definitely sorted out now.
Same here I have 2 of these one stock, the other is decked out with Inav, TBS receiver, TBS 1 watt vtx and 2 runcam phoenix cams. One on the tail. Powered with 2 lithium 21700 cells. CG right on the marks.
Mine was a disaster on the stock markers. On the servo wires it was perfect.
@@RCVideoReviews I will try it for sure, I just thought it flew well. I am still a rookie! lol
@@jayss1966 There's an old saying: CG forward flies poorly, CG aft flies once. You don't want to be crazy about it, but CG a little forward will normally ensure the plane comes back without crashing. It may want to land a little hot though so be ready for that.
I wonder if any of it has to do with that collar on the tail boom needing adjusted? Meaning, maybe once re-attached, it's not exactly in the same spot. The end of the tail could be further back, or forward, and either of those could impact where CG would be for the air frame. Just wondering.
I don't think it mattered much. The original location was fairly well marked on the boom and it was reinstalled in the same place. The control rods also helped. While the clevis was adjustable, after re-indexing, both pins were in virtually identical positions. The tail moment doesn't impact center of lift, just the effect of the control surface. COL remained constant and CG was on the factory marks, so I don't think reindexing the tailboom changed anything aerodynamically.
Today I flew it with the CG about 2mm aft of the servo wires and it was stable but I wouldn't move it back any further. I could feel it getting a little froggy at times.
Why it go in spiral? My Drift crashed like your and idk how to solve the problem, or solve the stall when happen
So the CG you used was right at the servo wires?
Yes.
I noticed something with my Drift before I crashed it this morning. With factory designed CG in manual mode, it went tip stall when the throttle is less than half.
Lot of that going around. It's a mixed bag though. I pushed my CG forward and it flies fine after that.
I had two or three interesting flights ,( like to get it flying in manual mode before using the lite), and the CG
is way to far back per the instructions ,I couldnt get it flying till it was on or around the wires as well . Its a shame that the model was damaged because of a error in the instructions on its first few flights . I left the FPV camera off the model on the maiden flights as it would probably been toast as well
I usually threw the aircraft with zero throttle to tes the CG before real flight.
That's a good strategy.
Yep, always surprised how few reviewers do a glide test before they do the real launch. I go right back to balsa kits form many years ago, always a glide test. I guess people don't bother now because planes are so easy to build and so robust built of foam.
Thanks, going to try that next.... Just been out, flicked into manual and death spiral.... Stab mode saved it just about a meter from certain death! ☠️😂
I'm glad to see it's flying nice and not dropping from the sky. But reading the comments, it's not really conclusive yet i think. Seems like there's a lot of variation on the CG from plane to plane for them to work properly ? Well well - time will tell.
I've seen comments both ways. This is from a conversation on the Livestream where I first showed the issue: th-cam.com/video/F1aRE3d71cg/w-d-xo.html
"Tom Fields • 3 days ago
@RC Video Reviews I found my best hand tossed glide C/G was the front edge of the foam bezel molded around the aileron servos.
I did an auto launch with a nice climb to altitude until the Drift started to circle. Changed to stability mode and the Drift flew well. I climbed again to a higher altitude, cut throttle for a nice glide and then switched into manual. The drift immediately dipped the left wing and started straight down. Switching back to stability made the Drift recover. "
"Tom Fields • 5 days ago
My Drift has the same behavior as yours. I'm going to the field this morning and try a glide test over grass with the C/G, +/- on the wing servo wires."
Lynn did a MAC calculation and it shows the CG on the spar. I was a few mm aft of that location for my 2nd flight.
You might want to try moving your CG forward of the marks slightly for your maiden. If it proves stable, you can always move it back.
I have never gotten Inav to work. Too many death spirals.
iNav or Kopilot? I have iNav working fairly well on a Nano Talon.
@@RCVideoReviews I have 3 kopilots all working flawlessly but have tried inav twice and just get the death spiral.
Under what circumstances are you getting a death spiral? Kopilot is really good out of the box. iNav takes some work, but it is infinitely more configurable.
Glad I never bought that shit plane.