KMP 87" Yak-54 What do you Think?
02-13-2005, 08:21 PM
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RE: KMP 87" Yak-54 What do you Think?
The fix.. Mark where you want to cut, peal back, and shape/glue a piece or 1/16" ply.. Cover with scrap piece of white ultracoat,, reiron covering back..
02-13-2005, 11:32 PM
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RE: KMP 87" Yak-54 What do you Think?
Here are some pics of my heap.
I did the stabilizers Friday Night, I cut the 9/16 back and angled it to the end of the original cut.
I used Gorilla glues and a piece of the original end plate cut down to fit INSIDE the sheeting.
I have yet to recover. I am using an MSA-10 to link the elevator servos. My hinge lines were not perfect...I used pin hinges so there is a little fudging needed for trim out...we will see.
My Q52 with smoke muffler fit nicely in the cowl...not enough room for a velocity stack on the carb. No Choke. Cut down motor box 40mm like Pauldo .
I know I got the Motor center line offset correct ..the cowl is just on funny. I used the paintlines for reference and that was Bad. The motor offset and thrust I did with a square and protractor.
I used enough offset to get the prop into center with the built in thrust .
I used 2 MPI switches and 2 2100 nimh 6v packs...both packs strapped down on a plate midway in the turtle deck. Antenna tube inside along the port side. My throttle servo in the motor box.
Tygon line wrapped over the tank for vent out the bottom of the cowl scoop. Fuel dot on side above wing.
She is ready.
Quadra 52s B&B muffler
4 JR 8411
1 Hitec 5945
1 Futaba 3004
Fm Futaba 7 channel RCVR
MSA-10 matcher
24 oz tank
2 2100 nimh packs 6V
Dave Patrick Tail Wheel
Weight...on my 30yr old bathroom scale...16.5lbs give or take an ounce.
CG on the tube or slighly behind it.
I did the stabilizers Friday Night, I cut the 9/16 back and angled it to the end of the original cut.
I used Gorilla glues and a piece of the original end plate cut down to fit INSIDE the sheeting.
I have yet to recover. I am using an MSA-10 to link the elevator servos. My hinge lines were not perfect...I used pin hinges so there is a little fudging needed for trim out...we will see.
My Q52 with smoke muffler fit nicely in the cowl...not enough room for a velocity stack on the carb. No Choke. Cut down motor box 40mm like Pauldo .
I know I got the Motor center line offset correct ..the cowl is just on funny. I used the paintlines for reference and that was Bad. The motor offset and thrust I did with a square and protractor.
I used enough offset to get the prop into center with the built in thrust .
I used 2 MPI switches and 2 2100 nimh 6v packs...both packs strapped down on a plate midway in the turtle deck. Antenna tube inside along the port side. My throttle servo in the motor box.
Tygon line wrapped over the tank for vent out the bottom of the cowl scoop. Fuel dot on side above wing.
She is ready.
Quadra 52s B&B muffler
4 JR 8411
1 Hitec 5945
1 Futaba 3004
Fm Futaba 7 channel RCVR
MSA-10 matcher
24 oz tank
2 2100 nimh packs 6V
Dave Patrick Tail Wheel
Weight...on my 30yr old bathroom scale...16.5lbs give or take an ounce.
CG on the tube or slighly behind it.
02-14-2005, 09:21 AM
#106
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RE: KMP 87" Yak-54 What do you Think?
Tail heavy with a g-62??????????/
what did he do...put a brick in the tail???
I had to put my battery packs in the tail to keep mine from being nose heavy!!!! My quadra and the g-62 are very close in weight.
mine cg's on the spar or just behind.
BUt a new development..... my 6XAS Futaba is creating a "Tick" in the digital servos. Sittiing statice it will just twitch the right aileron and rudder every 10 seconds or so.
I treid different receivers...nope....I trieda 4 channel Sksport cheapy...smooth....my 6XAS must be twitching it. I am going to try another computer radio tonit.e
Maiden when it is dry and warm.
what did he do...put a brick in the tail???
I had to put my battery packs in the tail to keep mine from being nose heavy!!!! My quadra and the g-62 are very close in weight.
mine cg's on the spar or just behind.
BUt a new development..... my 6XAS Futaba is creating a "Tick" in the digital servos. Sittiing statice it will just twitch the right aileron and rudder every 10 seconds or so.
I treid different receivers...nope....I trieda 4 channel Sksport cheapy...smooth....my 6XAS must be twitching it. I am going to try another computer radio tonit.e
Maiden when it is dry and warm.
02-19-2005, 12:13 AM
#108
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RE: KMP 87" Yak-54 What do you Think?
I cut my canopy AFTER I screwed it down on the top rear bulkhead of the hatch. this way I got the fit just right. Not really , but close. After my Pilots (Hand Sewn Squirrels my wife made) are in , and the gauges are glues in I will monokote the seam allthe way around. It is going to look bad no matter what...but from 15 feet away it will look OK.
I have been test running my motor , a quadra 52S , it is going to pull it well..
If my 9cap radio shows up USPS tomorrow it will maiden. I will not fly it with the 6XAS ..I don't trust it.
It looks like you did not have to cut down the motor box for yours, FF. I chopped 40mm off mine.
The only thing I REALLY worry about with this thing, is this: The wing gaps are SEVERE and even if you foamed them ...there is still an absence of rigidity between the wing and fuse.
Sure, the tube is strong. the sides are moderately strong. But, the gap is going to allow a twisting force to happen, and the absence of a tight fit, foamed or not, makes for flex that WILL cause damage over time. Unless of course you are going to fly it like an old lady. ...er....man.
So, it will be interesting to see what it looks like after 5 gallons. It will probably be battered and in need of structural repair before then. Probably in the wing root /sidewall area. JMHO.
FF, I see you using a heat gun on the wrinkly finish. Mine has permanent wrinkles that can't be worked out. 15 feet away, again it looks OK. I cracked a wing rib installing the an aileron servo. So, I gotta cut the covering CA it, and patch it. Good thing it is on the white
.
Test running also found loose braces, and screws, better to have that happen in the ground than in the air
Soon I will let this bird out of the nest. Then it will be on to the EF 87" Yak-54 that this thing was SUPPOSED to be. Mine will be here soon. If this Yak proves reliable and holds together it will be my everyday Practice Yak. Fingers crossed.
I have been test running my motor , a quadra 52S , it is going to pull it well..
If my 9cap radio shows up USPS tomorrow it will maiden. I will not fly it with the 6XAS ..I don't trust it.
It looks like you did not have to cut down the motor box for yours, FF. I chopped 40mm off mine.
The only thing I REALLY worry about with this thing, is this: The wing gaps are SEVERE and even if you foamed them ...there is still an absence of rigidity between the wing and fuse.
Sure, the tube is strong. the sides are moderately strong. But, the gap is going to allow a twisting force to happen, and the absence of a tight fit, foamed or not, makes for flex that WILL cause damage over time. Unless of course you are going to fly it like an old lady. ...er....man.
So, it will be interesting to see what it looks like after 5 gallons. It will probably be battered and in need of structural repair before then. Probably in the wing root /sidewall area. JMHO.
FF, I see you using a heat gun on the wrinkly finish. Mine has permanent wrinkles that can't be worked out. 15 feet away, again it looks OK. I cracked a wing rib installing the an aileron servo. So, I gotta cut the covering CA it, and patch it. Good thing it is on the white
.Test running also found loose braces, and screws, better to have that happen in the ground than in the air
Soon I will let this bird out of the nest. Then it will be on to the EF 87" Yak-54 that this thing was SUPPOSED to be. Mine will be here soon. If this Yak proves reliable and holds together it will be my everyday Practice Yak. Fingers crossed.
02-19-2005, 07:58 AM
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RE: KMP 87" Yak-54 What do you Think?
BossHoss,
Keep in mind that the wing sockets are inherently going to be "loose" around the wing as it is a tapered wing. My EF 87" Yak exhibits some space around the wing too (not nearly as bad as the picture shared here), but truth be told, the rounded area could be missing.
It does not contribute to the wing's strength or alignment in any meaningful way.
It sounds across the board that there was quite a few quality issues with this Yak, but not enough that an experienced and determined builder couldn't work out.
In contrast the EF Yak has been a perfect build, with everything coming together precisely.
As long as the surfaces are fairly true and the incidences remain accurate, this Yak ought to fly quite well as that is what Chris brought to the table to make it happen in the first place.
Keep in mind that the wing sockets are inherently going to be "loose" around the wing as it is a tapered wing. My EF 87" Yak exhibits some space around the wing too (not nearly as bad as the picture shared here), but truth be told, the rounded area could be missing.
It does not contribute to the wing's strength or alignment in any meaningful way.
It sounds across the board that there was quite a few quality issues with this Yak, but not enough that an experienced and determined builder couldn't work out.
In contrast the EF Yak has been a perfect build, with everything coming together precisely.
As long as the surfaces are fairly true and the incidences remain accurate, this Yak ought to fly quite well as that is what Chris brought to the table to make it happen in the first place.
02-19-2005, 10:43 PM
#110
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RE: KMP 87" Yak-54 What do you Think?
Maiden Report.
CG slightly nose heavy. Flew Great , easy landing , needed a noticable amount of up elevator to trim. Flew neutral, high alpha KE great. Vertical.
3rd flight = structural failure at the wing root, 1/4 throttle induced flutter, wing rotation and alum tube fold and crash, nose in. The nylon bolts that came with the wing sheared off , one of them in flight and the wing rotated. WOW.
Wing panels undamaged, tail undamaged, motor box and wing sockets cracked up . Cowl destroyed. Gear OK.
Fun for three flights and it crashed itself. Done.
Motor seems ok. Have to check for bent crank.
I am piecing it back together, or I should say, I started. 50/50 it flies again.
It flew well, and everyone said it was hard to believe it was a "reject" of any kind. But the horror inside was well hidden. I actually liked flying it, until it came apart.
The sad part is, my wife made the pilots, and she made wing bags for it , that I never got to use. She had them ready for me when I got home with the wreck. Maybe I can piece it together. But with the EF YAK coming here next week, I don;t know if I will be able to hold interest in it.
CG slightly nose heavy. Flew Great , easy landing , needed a noticable amount of up elevator to trim. Flew neutral, high alpha KE great. Vertical.
3rd flight = structural failure at the wing root, 1/4 throttle induced flutter, wing rotation and alum tube fold and crash, nose in. The nylon bolts that came with the wing sheared off , one of them in flight and the wing rotated. WOW.
Wing panels undamaged, tail undamaged, motor box and wing sockets cracked up . Cowl destroyed. Gear OK.
Fun for three flights and it crashed itself. Done.
Motor seems ok. Have to check for bent crank.
I am piecing it back together, or I should say, I started. 50/50 it flies again.
It flew well, and everyone said it was hard to believe it was a "reject" of any kind. But the horror inside was well hidden. I actually liked flying it, until it came apart.
The sad part is, my wife made the pilots, and she made wing bags for it , that I never got to use. She had them ready for me when I got home with the wreck. Maybe I can piece it together. But with the EF YAK coming here next week, I don;t know if I will be able to hold interest in it.
02-20-2005, 08:48 AM
#112
RE: KMP 87" Yak-54 What do you Think?
couldn't blame it on CA hinges...don't go there. It was most likely a structural fault, given this plane's rep. It could be poor mechanical advantage or not sealing the gap, but, even not knowing bosshoss, I don't think he would do that.
02-20-2005, 09:27 AM
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RE: KMP 87" Yak-54 What do you Think?
The aileron horn points in the ailerons came apart, busted, worked free, from the ailerons and the resulting flutter at 20mph was enough to snap the nylon wing bolts and let the left wing panel rotate TE down.
I was able to shut it down when I saw the flutter, and I thought I saved it. It was level the whole time. But 1 second or so after it slowed down, everyone heard a loud SNAP , and the wing rotated and immediately went nose down. I was able to go idle off, and pumped the elevator to hold the nose up until it hit . It looked like the tube bent before impact, also. It went down VERY SLOWLY.
I may be able to spit ball and super glue it together , then glass it
but it will be a little heavier.
I will post pics. I don;t have a crash pic at the field, but before shots, and a shot of it on the workbench with the nose soft.
Amazingly the wingpanels are untouched. So , I am going to give it a go.
I really like the way it flew, it had everyone at our field saying it wasn't flying like a "reject".
FF ..go with a CF tube, and steel bolts , man. And cut the covering of the ailerons and look at the horn attachment points...something I DID NOT do.
My surfaces were gap taped, pin hinged. I will show the aileron horn failure in a picture.
I was able to shut it down when I saw the flutter, and I thought I saved it. It was level the whole time. But 1 second or so after it slowed down, everyone heard a loud SNAP , and the wing rotated and immediately went nose down. I was able to go idle off, and pumped the elevator to hold the nose up until it hit . It looked like the tube bent before impact, also. It went down VERY SLOWLY.
I may be able to spit ball and super glue it together , then glass it
but it will be a little heavier.
I will post pics. I don;t have a crash pic at the field, but before shots, and a shot of it on the workbench with the nose soft.
Amazingly the wingpanels are untouched. So , I am going to give it a go.
I really like the way it flew, it had everyone at our field saying it wasn't flying like a "reject".
FF ..go with a CF tube, and steel bolts , man. And cut the covering of the ailerons and look at the horn attachment points...something I DID NOT do.
My surfaces were gap taped, pin hinged. I will show the aileron horn failure in a picture.
02-21-2005, 06:47 AM
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RE: KMP 87" Yak-54 What do you Think?
The Squirrels have a worried look on there face in the first picture. Suppose they knew what was up?
Sorry to see she went in and good luck on the rebuild.
Sorry to see she went in and good luck on the rebuild.
02-21-2005, 09:47 AM
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RE: KMP 87" Yak-54 What do you Think?
Sorry, but i did not get a crash picture at the scene. Someone did, and I will post it. It looked like a crumpled butterfly after a Thunderstorm.
Here are some of the rebuild pictures. The entire forward part of the fuse was cracked up , albeit cleanly. Everything in fornt of the the turtle deck was soft. The canopy and Squirrels survived with only a dent and a crack. I made sure to pick up all the bits..[8D]
I spent more than a couple hours Thin CA'ing the fuse back straight. The Rudder tray helped to index it all back together straight. I had to repair almost all the stringers, and CA the formers strraight, The landing gear mount and wingtube holder held together and kept shape so I built around that. After CA'ing it straight, I spayed it down with water, and paintbrushed Gorilla glue on all the repaired pieces. So far I ve added 2ounces weight.
After the motor baox goes back together, I will light glass the entire inside. Just to be safe
The aileron hole from the horn is the damning issue. Very weak and it is what caused the flutter , I still dont know why the wing rotated, either the bolt snapped from the vibration, or it unscrewed itself becuase of the vibes, came out enough to rotate and snapped. I donlt know.
I did not remove the canopy before the third flight , so I cant be certain it was still tight.
Probably this crash was 50/50 50% weak build, 50% my negligence for not being more anal.
But it WILL fly again. Maybe not straight, maybe not pretty, but it will fly. I have second spare cowl, but I am going to use the crashed one after glassing it. THe wheel pants need a little glass too. And I have to extract 2 sheared bolts out of the wing, they will be metal next time.
Here are some of the rebuild pictures. The entire forward part of the fuse was cracked up , albeit cleanly. Everything in fornt of the the turtle deck was soft. The canopy and Squirrels survived with only a dent and a crack. I made sure to pick up all the bits..[8D]
I spent more than a couple hours Thin CA'ing the fuse back straight. The Rudder tray helped to index it all back together straight. I had to repair almost all the stringers, and CA the formers strraight, The landing gear mount and wingtube holder held together and kept shape so I built around that. After CA'ing it straight, I spayed it down with water, and paintbrushed Gorilla glue on all the repaired pieces. So far I ve added 2ounces weight.
After the motor baox goes back together, I will light glass the entire inside. Just to be safe
The aileron hole from the horn is the damning issue. Very weak and it is what caused the flutter , I still dont know why the wing rotated, either the bolt snapped from the vibration, or it unscrewed itself becuase of the vibes, came out enough to rotate and snapped. I donlt know.
I did not remove the canopy before the third flight , so I cant be certain it was still tight.
Probably this crash was 50/50 50% weak build, 50% my negligence for not being more anal.
But it WILL fly again. Maybe not straight, maybe not pretty, but it will fly. I have second spare cowl, but I am going to use the crashed one after glassing it. THe wheel pants need a little glass too. And I have to extract 2 sheared bolts out of the wing, they will be metal next time.
02-21-2005, 10:12 AM
#120
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RE: KMP 87" Yak-54 What do you Think?
Bum deal Boss... Though I've never been a fan of how this bird came to be, I wouldn't wish this on anyone... hope you can get it back together and in the air again... Looks like you can...
02-21-2005, 11:29 AM
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RE: KMP 87" Yak-54 What do you Think?
Thanks I have emailed a bunch of places now. I have a 25mm tube 920mm long. The 1" is too big.
That is about all I need to buy for this, other than different aileron hardware.
That is about all I need to buy for this, other than different aileron hardware.