Skymaster Mig-29 OVT Single with S-bus Build
04-20-2014, 06:58 AM
#127
My Feedback: (11)
If anyone doesnt object I would like to post how I do my vert stabs and rudders.
Issues:
Rudders are hollow and flimsy, nothing inside them. I have no idea how a control horn would even stay in the rudder unless somehow you managed to glue it to both sides of the rudder (bottom of control horn glued to side and top glued to other side). Mine are not long enough to do that...
Vert stabs are thin, so mounting blocks can move when glued to one side of the stab, as the skin flexes a lot. this means the servos can move inside the stab. This itself will cause pseudo flutter.
Vert stabs are held on with one 3mm bolt towards the front only.
Guide pins easily break lose.
Stabs do not sit flush against the fuse and can rock quite a bit at the joint.
The CFspare only sticks out 1.5" and only goes inside the stab a few inches. the rest of the stab is hollow.
A couple things I am doing is using addition wood that attaches to the servo mounting blocs to spread out the load inside the vert stab, and also ensuring the block are attached with extra wood to both sidi\es of the stab. Doing this alone added quite of bit of strength to the stab.
I am filling the inside of my rudders with gorilla glue. This will get rid of most of the flex and give additional attachment point for the horn to glue to.
I will be sanding all the paint off the fuse and vert stab where they mate up, ensuring a flush fit and using hysol to glue them down. I could use additional bolts but I dont want to add additional holes to a very small structure that supports the elevators. I hate gluing them but not chancing it.
I am not sure what I will do about the vert stabs being flimsy and hollow yet. I am consdering some CF rods glued to the inside on each side that stick out and go into the fuse. Dont want to drill more holes but may have no choice.
I'l get some pics up IF noone objects.
Issues:
Rudders are hollow and flimsy, nothing inside them. I have no idea how a control horn would even stay in the rudder unless somehow you managed to glue it to both sides of the rudder (bottom of control horn glued to side and top glued to other side). Mine are not long enough to do that...
Vert stabs are thin, so mounting blocks can move when glued to one side of the stab, as the skin flexes a lot. this means the servos can move inside the stab. This itself will cause pseudo flutter.
Vert stabs are held on with one 3mm bolt towards the front only.
Guide pins easily break lose.
Stabs do not sit flush against the fuse and can rock quite a bit at the joint.
The CFspare only sticks out 1.5" and only goes inside the stab a few inches. the rest of the stab is hollow.
A couple things I am doing is using addition wood that attaches to the servo mounting blocs to spread out the load inside the vert stab, and also ensuring the block are attached with extra wood to both sidi\es of the stab. Doing this alone added quite of bit of strength to the stab.
I am filling the inside of my rudders with gorilla glue. This will get rid of most of the flex and give additional attachment point for the horn to glue to.
I will be sanding all the paint off the fuse and vert stab where they mate up, ensuring a flush fit and using hysol to glue them down. I could use additional bolts but I dont want to add additional holes to a very small structure that supports the elevators. I hate gluing them but not chancing it.
I am not sure what I will do about the vert stabs being flimsy and hollow yet. I am consdering some CF rods glued to the inside on each side that stick out and go into the fuse. Dont want to drill more holes but may have no choice.
I'l get some pics up IF noone objects.
04-20-2014, 07:19 AM
#128
That sounds like a good start. I was worried about the elevator, both sides were still intact after a crash that split festo fittings in two! My rudder to fuse bolts were still in place and tight, but both fins were off the fuse. My rudder servos were glued in with mounting blocks, it was a bear getting them out. I used Hysol to put the control horns in, can't recall if they were off after crash. I cannot figure out if it was rudder flutter that lead to the whole vert fin coming off, or just the. Two fins coming off. I don't think I could have seen the rudders themselves fluttering, it was very obvious that the fins were before it went in. The vert fins are quite large, mine seemed to seat on the fuse very well, but I do remember being able to flex them right to left a little. Same with the elevator at the tips up and down...
I didn't cut cut any corners on building this thing, hard to fix what you don't know is broken.
I emailed Anton just to give a heads up, no reply...
I didn't cut cut any corners on building this thing, hard to fix what you don't know is broken.
I emailed Anton just to give a heads up, no reply...
04-20-2014, 07:42 AM
#130
Last edited by DrScoles; 04-20-2014 at 07:47 AM.
04-22-2014, 02:26 AM
#131
That's a real shame Mike. Really sad to see this happen mate. It looks like you have done everything to prevent this happening. The rudders on mine were not perfect but I felt they were up to the task. I glued some mounting blocks in the fin touching both sides with a notch cut out for the servo mounting angles to attach to. I was using JR 3421s which just squeezed in.
The fins did flex a bit but not to much. I used the single bolt to attach the rudder but I also glued the front support in just to stop any movement. I had over 50 flights with a P200 doing some hard knife edge stuff and slow rolls with no problems. I have sold the plane to a friend who flys it harder than me and it's approaching 100 flights with no issues. I know Dantley flew his Mig hard as well and no issues there either.
It really looks like you have engineered everything really well Mike so there is a variable somewhere that needs to be investigated. Defiantly doesn't look like your fault. It could be a change in construction methods at the factory, a radio issue, a hardware issue, I'm not sure.
Anyway Mike sorry for your loss and keep us informed if you find anything.
Kind Regards
Levi
The fins did flex a bit but not to much. I used the single bolt to attach the rudder but I also glued the front support in just to stop any movement. I had over 50 flights with a P200 doing some hard knife edge stuff and slow rolls with no problems. I have sold the plane to a friend who flys it harder than me and it's approaching 100 flights with no issues. I know Dantley flew his Mig hard as well and no issues there either.
It really looks like you have engineered everything really well Mike so there is a variable somewhere that needs to be investigated. Defiantly doesn't look like your fault. It could be a change in construction methods at the factory, a radio issue, a hardware issue, I'm not sure.
Anyway Mike sorry for your loss and keep us informed if you find anything.
Kind Regards
Levi
04-22-2014, 02:43 AM
#132
Join Date: Dec 2006
Location: Nicosia, CYPRUS
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My SM Mig29 is on the way to me. I will receive it end of the week or beginning of next week.
I will use 3421 for Ailerons and Rudders. According your posts 3421 will not fit without modifications. Correct?
What about 3421 on ailerons?
In order to achieve correct CG without to add extra weight I have to install things as forward as I can or not?
Your help guys ans experience will be very helpful and valuable for me.
Thanking you in advance.
According your post vertical stabilizers are weak and I must pay extra attention.
Are they any other weak point that I must pay attension?
I will use 3421 for Ailerons and Rudders. According your posts 3421 will not fit without modifications. Correct?
What about 3421 on ailerons?
In order to achieve correct CG without to add extra weight I have to install things as forward as I can or not?
Your help guys ans experience will be very helpful and valuable for me.
Thanking you in advance.
According your post vertical stabilizers are weak and I must pay extra attention.
Are they any other weak point that I must pay attension?
04-22-2014, 07:05 AM
#133
Thanks Levi, I do think I was pretty conscientious on the build. I did the rudder blocks just like you described, hysol'd in hardwood blocks and a slot for the servo tabs, then glued them in. They could not budge. For the fin strength, hard to fix what you can't see. mhadjiky, mine balanced just fine, but I had four servos in the back for the OVT. without them, I would think that sticking stuff farther forward would be a good idea.
What's funny, is that if this was an FEJ jet that fluttered, every single person on this forum would be chiming in heaping I told you so's and condemning the company. Hopefully it was an isolated incident. Disappointed that Anton and Patty didn't even return my emails. I wasn't asking for anything, just explaining what happened.
What's funny, is that if this was an FEJ jet that fluttered, every single person on this forum would be chiming in heaping I told you so's and condemning the company. Hopefully it was an isolated incident. Disappointed that Anton and Patty didn't even return my emails. I wasn't asking for anything, just explaining what happened.
04-22-2014, 07:29 AM
#134
So bad you don't have video to posted and maybe then the skymaster will do more for you ,the have very good reputation and this flutter proves than theare no perfect jets ,Anton should contact you with all neccecery informations from you to prevent situation like this crash .
04-24-2014, 06:20 AM
#138
I ran it on the ground at full throttle for almost five minutes at home testing temps with an infra red gun the whole time. If anything was going to melt, it would have happened then. The pipe and the install was solid. You could hold your hand anywhere on the fuse comfortably, and I have dentist weenie sensitive hands because I wear gloves all day!
04-25-2014, 06:47 AM
#140
I would see how much lateral play is in the fins. I have no idea how you would reinforce that area. The big carbon spar that is in the fin was intact on both of them. There seemed to be enough angles around the top of the deck that would give some rigidity, maybe not. Both the fins were destroyed, so not sure if the flex was coming within the fins themselves.
All I know is it looked like both of them were, for lack of a better word, glimmering… then it was obvious they were wobbling back and forth as it was going in. They did not fall off.
In looking at the pics again, I think I may have figured something out. There isn't any reinforcement with the piece of plywood under the glass that the fin bolts to and the sides that go out laterally. Where you see the arrows, should there have been heavier glass or a former here to resist the fin from moving laterally-causing the back of the fuse to flex? The spar box is pretty big, but it doesn't go fore and aft very far. Should the spar have gone farther up into the fin? These are things I don't have experience in. I'm a tooth carpenter, not an engineer.
04-26-2014, 04:04 PM
#142
No idea on the P180. The plane is heavy. Dantley mentioned a P200 being more ideal. I took off at full power and immediately brought it back to mid-2/3 to trim it. I might have got 4-5 circuits before it went in.
I flew three flights on the avanti today with the K180. that thing is a beast. Starts much faster than a jetcat, but I question the 20oz of fuel at full throttle. On five flights, this thing is thirsty, I don't think the 20oz drops off much when at half throttle.
I flew three flights on the avanti today with the K180. that thing is a beast. Starts much faster than a jetcat, but I question the 20oz of fuel at full throttle. On five flights, this thing is thirsty, I don't think the 20oz drops off much when at half throttle.
04-27-2014, 12:59 PM
#143
My Feedback: (11)
Here are a couple pics of my first concern. I am surprised a single bolt holds the fin on. This creates a problem in that the fin has a lot of play and all the forces from the fin are put into a very small area on the fuse.
With the bolt cranked down, you can see I can still create a gap between the fuse and fun with a slight pull on the back of the fin. I know the forces wont pull this way in flight, but it shows how much slop there is. The fin has side to side movement of 1/2", which is a lot IMO. I have a mig foamy with 0 slop in the top fins.
The 2nd picture, right below the carbon spar (which I think is a glass spar BTW), that black dot is a magnet. That means there is probably another blind nut under that spot. Its probably meant to have two bolts but was glass over? that is the only other spot the magnet sticks other than the visible blind nut hole.
More to come..
With the bolt cranked down, you can see I can still create a gap between the fuse and fun with a slight pull on the back of the fin. I know the forces wont pull this way in flight, but it shows how much slop there is. The fin has side to side movement of 1/2", which is a lot IMO. I have a mig foamy with 0 slop in the top fins.
The 2nd picture, right below the carbon spar (which I think is a glass spar BTW), that black dot is a magnet. That means there is probably another blind nut under that spot. Its probably meant to have two bolts but was glass over? that is the only other spot the magnet sticks other than the visible blind nut hole.
More to come..
04-30-2014, 10:40 AM
#144
I wouldn't worry about the single bolt if it seated well. Mine seated perfectly, zero gap. I just don't think the fuse or the spar going into the fin was remotely long enough.
Skymaster or BVM, would be really nice if you had the courtesy to return my emails….. This is comedy. FEJ gets crucified, sky master gets a free pass? This was obviously a structural failure on a brand new plane.
Skymaster or BVM, would be really nice if you had the courtesy to return my emails….. This is comedy. FEJ gets crucified, sky master gets a free pass? This was obviously a structural failure on a brand new plane.
04-30-2014, 12:59 PM
#145
My Feedback: (11)
SM gets away with a lot because FEJ is so bad.
What are your suggestions? Put another spar up the fins? Mine really move around I am still considering gluing them down on the ends so I can cut then off easily if I ever need to. A dime size spot of hysol on both ends should add significant strength.
What are your suggestions? Put another spar up the fins? Mine really move around I am still considering gluing them down on the ends so I can cut then off easily if I ever need to. A dime size spot of hysol on both ends should add significant strength.
Last edited by essyou35; 04-30-2014 at 05:05 PM.
04-30-2014, 11:33 PM
#147
Sorry for the loss of your plane, its really a shame to see an accident obviously caused by manufacturing defect. I am really surprised that BVM / Skymaster do not return your emails ... I own 2 skymaster planes and so far I thought they would believe in good customer communication.
T
05-01-2014, 05:06 PM
#148
Join Date: Mar 2005
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Sorry to hear the loss.We haven't received your mail and didn't find it after search in mailbox.Please resend mail to [email protected] and we will get back to you as soon as possible.
Best regards
John
Skymaster
05-01-2014, 06:46 PM
#150
My Feedback: (2)
Hey Dr Scoles
Sorry for the loss of your plane, its really a shame to see an accident obviously caused by manufacturing defect. I am really surprised that BVM / Skymaster do not return your emails ... I own 2 skymaster planes and so far I thought they would believe in good customer communication.
T
Sorry for the loss of your plane, its really a shame to see an accident obviously caused by manufacturing defect. I am really surprised that BVM / Skymaster do not return your emails ... I own 2 skymaster planes and so far I thought they would believe in good customer communication.
T
Shaz
