BVM Composite Bandit Build Thread. Yes from 1998.
01-11-2018, 08:23 PM
#76
Roger not sure how 4 is enough? Gear up, down, door open and close. Then you need brakes! So it should have 5 right?
I did a bad thing today, I sold the K100g I had for this and ordered a K120g2.
I decided after all this work I wanted the best.
I did a bad thing today, I sold the K100g I had for this and ordered a K120g2.
I decided after all this work I wanted the best.
01-11-2018, 10:03 PM
#77
K120 + Comp Bandit.. Sounds a great combo..
Four lines is standard plumbing for the SB. The "door open" line is tee connected into the gear down circuit. The "door close" line is on its own circuit, and switched by a button switch. Both the main slider switch and button switch are controlled with one servo, which is slowed down to achieve sequencing.
It is very simple and very effective, only uses one slider valve, one button valve, one servo, and and reduces your wing plumbing to 4 lines. . Photo is a little blurry, but you should get the idea..
Four lines is standard plumbing for the SB. The "door open" line is tee connected into the gear down circuit. The "door close" line is on its own circuit, and switched by a button switch. Both the main slider switch and button switch are controlled with one servo, which is slowed down to achieve sequencing.
It is very simple and very effective, only uses one slider valve, one button valve, one servo, and and reduces your wing plumbing to 4 lines. . Photo is a little blurry, but you should get the idea..
01-11-2018, 10:34 PM
#78
With all due respect I don't like that button door closed system. (Although I do use the over travel button for brakes) When the gear goes up, their is no positive pressure holding the doors open. I prefer to hold them open with full pressure.
I also sequence the doors, I don't like the doors hanging open with the gear down, too easy to damage them
. Just my experience
I also sequence the doors, I don't like the doors hanging open with the gear down, too easy to damage them
. Just my experience
01-12-2018, 09:46 AM
#79
OH I seen that trip valve in my kit I have not researched how use it yet. I have a spare sequencer and that would allow the doors to close on landing. Have you ever tried the dual electronic valves that don't need servos. That would eliminate the need for two servos.
I do think BVMs setup is creative for sure, especially since the electronic valves did not exist back then.
I do think BVMs setup is creative for sure, especially since the electronic valves did not exist back then.
01-13-2018, 06:26 PM
#80
Ive been working on the wings, main formers/wing strut, cutting ailerons etc. I decided to switch over the the tail section to ensure I have all the parts. At a glance it appears I do.
I know the elevators need 1/8 off the molding, any other tips?
I know the elevators need 1/8 off the molding, any other tips?
01-14-2018, 08:10 PM
#81
I had a big scare today but I think I am ok, I THINK. Let me know!
I have NO idea how the guy who bought this jet in 1998 didnt have the plans, it would not be possible to build it without the plans unless you've done it before.
Case and point, the elevators come mostly cut out for you, the are cut out horizontally for you across the stab, all you have to do is make a roughly 2" cut to remove the elevator from the stab.
There are two pieces of bass wood, one is 1/8 and the other 1/16 and the serve as end caps on the elevator and the stab respectively. BVM requires the builder to sand off material in order to account for these end caps. So I take my elevator and place it on the plans, do some measuring, marking, leaving some room for error etc and I sand my elevator down. Then I put all the wood in place with tape and have a look, and it appears the elevator is now too small even though it matches perfectly to the plans. I tripled checked, the plans tell you exactly where to trim to, it shows the elevator and the end caps very clearly.
On the stab, I removed the material up to the scribe lines like it says, but it appears I need to remove another 1/4"? I tried to line the stabs up with the plans but its impossible since they are not flat. I only sanded slightly on the elevators, not enough to remove 1/16" of material, I also checked against the other stab which I didnt touch yet, the same result.
So I am assuming the plans are correct, make the elevator match and sand off the end point of the stab to match, sound like a plan? The scribe lines may be wrong?
Also I assume these stabs are symetrical, so there is not a right and a left, but thought I would ask, they do not appear to be marked.
Finally a small thing I noticed, I suck at sanding. I have a 10" great planes alumunium sanding block and I still round things. Ill have to put 1/8" balsa down and flat out that elevator on the end. You can see in the pic I rounded the darn thing a bit, had to fix up my ailerons too. I had same issue with my YA f-18. I think the key may be to change sand paper more often when sanding carbon fiber.
I know some questions I ask are obvious but better safe than sorry, and I highly appreciate the help. I cannot get new parts for this so I am stuck fixing anything a ruin. You're saving me time!
Explanation of pics:
1) stab is trimmed to scribe lines, elevator matches plans, they dont line up.
2) comparing the inside of the stab where the elevators go, the black mark is where the elevator ends, note how the end of the stab goes past 0. (Between the 0 and the black mark is the length the plans have for the elevator + end caps)
3) measure the plans, the small end of the elevator, this measurement takes into account the end caps, the black mark is how long it is in the plans, compare this to #2.
4) A big picture of the plans of the stab, note the "trim to this line" comments.
5) measuring the elevator small end, to show it matches the plans exactly (may like .01 too big)
I have NO idea how the guy who bought this jet in 1998 didnt have the plans, it would not be possible to build it without the plans unless you've done it before.
Case and point, the elevators come mostly cut out for you, the are cut out horizontally for you across the stab, all you have to do is make a roughly 2" cut to remove the elevator from the stab.
There are two pieces of bass wood, one is 1/8 and the other 1/16 and the serve as end caps on the elevator and the stab respectively. BVM requires the builder to sand off material in order to account for these end caps. So I take my elevator and place it on the plans, do some measuring, marking, leaving some room for error etc and I sand my elevator down. Then I put all the wood in place with tape and have a look, and it appears the elevator is now too small even though it matches perfectly to the plans. I tripled checked, the plans tell you exactly where to trim to, it shows the elevator and the end caps very clearly.
On the stab, I removed the material up to the scribe lines like it says, but it appears I need to remove another 1/4"? I tried to line the stabs up with the plans but its impossible since they are not flat. I only sanded slightly on the elevators, not enough to remove 1/16" of material, I also checked against the other stab which I didnt touch yet, the same result.
So I am assuming the plans are correct, make the elevator match and sand off the end point of the stab to match, sound like a plan? The scribe lines may be wrong?
Also I assume these stabs are symetrical, so there is not a right and a left, but thought I would ask, they do not appear to be marked.
Finally a small thing I noticed, I suck at sanding. I have a 10" great planes alumunium sanding block and I still round things. Ill have to put 1/8" balsa down and flat out that elevator on the end. You can see in the pic I rounded the darn thing a bit, had to fix up my ailerons too. I had same issue with my YA f-18. I think the key may be to change sand paper more often when sanding carbon fiber.
I know some questions I ask are obvious but better safe than sorry, and I highly appreciate the help. I cannot get new parts for this so I am stuck fixing anything a ruin. You're saving me time!
Explanation of pics:
1) stab is trimmed to scribe lines, elevator matches plans, they dont line up.
2) comparing the inside of the stab where the elevators go, the black mark is where the elevator ends, note how the end of the stab goes past 0. (Between the 0 and the black mark is the length the plans have for the elevator + end caps)
3) measure the plans, the small end of the elevator, this measurement takes into account the end caps, the black mark is how long it is in the plans, compare this to #2.
4) A big picture of the plans of the stab, note the "trim to this line" comments.
5) measuring the elevator small end, to show it matches the plans exactly (may like .01 too big)
Last edited by essyou35; 01-14-2018 at 08:25 PM.
01-15-2018, 05:16 AM
#85
Its not all that bad to build at all, its not perfect though. The written instructions are wrong on some occasions but the plans are perfect.
Im also new to building and this may be my last thing I ever built. Though I was recently told this does not count as building either...
Im also new to building and this may be my last thing I ever built. Though I was recently told this does not count as building either...
01-16-2018, 08:54 PM
#86
Elevators turned out ok so far, the scribe lines for the end of the elevator are wrong, so it freaked me out for no reason.
So far this jets going well, but it is VERY messy. All the sanding on on the CF skin and wood just makes a mess!
My goal is to have the tail ready to install (instructions say must be completed in 1 build session). But before I do that on the the vert stab to ensure I have the needed hardware for that as well, it appears I do but sometimes have to get into it to know for sure.
I need to order my engine mount too.
So far this jets going well, but it is VERY messy. All the sanding on on the CF skin and wood just makes a mess!
My goal is to have the tail ready to install (instructions say must be completed in 1 build session). But before I do that on the the vert stab to ensure I have the needed hardware for that as well, it appears I do but sometimes have to get into it to know for sure.
I need to order my engine mount too.
01-18-2018, 07:15 AM
#89
Been having fun looking through the original BVM website from 1998. There are other snapshots throughout the year.
Wayback Machine
Click on jet kits and have a look at the bandit and links!
Was this one nuclear powered?
Wayback Machine
Click on jet kits and have a look at the bandit and links!
Was this one nuclear powered?
01-18-2018, 07:25 AM
#90
That was the original Bandit "T", designed for a JPX turbine. That is a propane tank, just like on your barbecue. It had a 90 degree rotating nose retract to clear the bottom of the tank.
As for the fin mod, keep the little forward locating pin, but add a 4-40 bolt behind it. You need an access hole in the fin leading edge to get a ball driver in to tighten it. You mount a little plywood plate under the fin in the fuse to hold a 4-40 blind nut. You have got to get the fin on there securely especially if you want to fly fast.
As for the fin mod, keep the little forward locating pin, but add a 4-40 bolt behind it. You need an access hole in the fin leading edge to get a ball driver in to tighten it. You mount a little plywood plate under the fin in the fuse to hold a 4-40 blind nut. You have got to get the fin on there securely especially if you want to fly fast.
01-23-2018, 06:42 PM
#94
I noticed in several photos people have used alternate control horns for the bandit. Im setting on some of these:
http://www.dreamworksrc.com/catalog/...Horn-Type-A-(4)
and these all plastic:
http://www.dreamworksrc.com/catalog/...Horn-Type-B-(4)
I want to use a dual ballink from an rc car on the ailerons where one is reversed thread. So I want the horn up off the aileron, it apears the stock horn sits pretty low. Will these horns be ok or should I get some metal or CF?
Here is a pic of one with different horns:
http://www.dreamworksrc.com/catalog/...Horn-Type-A-(4)
and these all plastic:
http://www.dreamworksrc.com/catalog/...Horn-Type-B-(4)
I want to use a dual ballink from an rc car on the ailerons where one is reversed thread. So I want the horn up off the aileron, it apears the stock horn sits pretty low. Will these horns be ok or should I get some metal or CF?
Here is a pic of one with different horns:
02-18-2018, 06:29 PM
#95
So here's where I am at. I have the inlets (aka cheek cowls) taped up, and the ducting pushed into the inlets. The bypass extension is cut to 2" and glued onto the bypass. Have everything taped up for now. Mr Matt if you can answer a couple questions:
The ducts have about a 1/8" gap on the outside edge of the inlets, is this normal?
The instructions are confusing here:
Tape inlets on, position ducts into the inlets, make height jig and glue to top of fuse, get everything lined up.
All the sudden it forgets the inlets are already taped on, and starts telling me to glue them on and tape then down.
Why did I just do all that alignement work? Why not just glue them on first, then line up everything? I guess I assume I am supposed to remove them but now I have everything lined up and it was for nothing?
Seems to me that with everything lined up, I could glue the ducting into the inlets, then I can remove the inlets with the ducting glue into them (back part of ducting not glued together yet) then glue the inlets and go from there?
The last pic is from the bypass looking out the ducting, you can see the gap I a speaking of (pic is oriented wrong on my pc) but its on the bottom which should rotated would be on the right side.
The ducts have about a 1/8" gap on the outside edge of the inlets, is this normal?
The instructions are confusing here:
Tape inlets on, position ducts into the inlets, make height jig and glue to top of fuse, get everything lined up.
All the sudden it forgets the inlets are already taped on, and starts telling me to glue them on and tape then down.
Why did I just do all that alignement work? Why not just glue them on first, then line up everything? I guess I assume I am supposed to remove them but now I have everything lined up and it was for nothing?
Seems to me that with everything lined up, I could glue the ducting into the inlets, then I can remove the inlets with the ducting glue into them (back part of ducting not glued together yet) then glue the inlets and go from there?
The last pic is from the bypass looking out the ducting, you can see the gap I a speaking of (pic is oriented wrong on my pc) but its on the bottom which should rotated would be on the right side.
02-18-2018, 07:43 PM
#96
Yessss.. I do recall that fitting the cheek cowls and inlet ducts were a bit of a mission.. If my memory serves, the cheek cowls are glued in first, followed by the inlet ducts. All of the pre fitting and taping in place is to ensure you have a really good fit of all parts prior to gluing. Actually I am confident of this now.. I remember having to trim the internal cheek cowl/fuse flanges, to fit the ducts in. This was done after gluing the cheek cowls in.
Check out this thread on installing the cheek cowls on a BVM F4 by the absolute master builder John Remond. Post #256 has lots of really good info. Pic # 2 of this post shows 1/8 balsa sticks glued to masking tape on the cowl/fuse joint. This technique is the very best way to make these kind of joints.
http://www.rcuniverse.com/forum/rc-j...-build-11.html
Actually this is a great thread to read just for entertainment. RCU used to be full of this kind of stuff. Times change.
All my parts fitted pretty well. I do recall that the duct/cowl fit was not entirely perfect, but probably not 1/8" gaps. I did manage to get the joint invisible using filler. I remember using some foam rubber pieces stuffed down, between the cheek cowl and duct during the glue cure. This put some pressure on the duct so the inside wall of the duct is hard up against the fuse.
Check out this thread on installing the cheek cowls on a BVM F4 by the absolute master builder John Remond. Post #256 has lots of really good info. Pic # 2 of this post shows 1/8 balsa sticks glued to masking tape on the cowl/fuse joint. This technique is the very best way to make these kind of joints.
http://www.rcuniverse.com/forum/rc-j...-build-11.html
Actually this is a great thread to read just for entertainment. RCU used to be full of this kind of stuff. Times change.
All my parts fitted pretty well. I do recall that the duct/cowl fit was not entirely perfect, but probably not 1/8" gaps. I did manage to get the joint invisible using filler. I remember using some foam rubber pieces stuffed down, between the cheek cowl and duct during the glue cure. This put some pressure on the duct so the inside wall of the duct is hard up against the fuse.
02-18-2018, 07:56 PM
#97
Had my SB out on the weekend. so took some pics of he fin/fuse connection . This may make Matts comments a bit clearer. The 4-40 cap head bolt is retained in a small aluminium tube mounted vertically in the fin. The nut is a under the little plate in the fuse.. This was a mod that BVM brought out on all Bandits.
Keep at it, and keep posting. Great project.
Keep at it, and keep posting. Great project.
02-19-2018, 11:16 AM
#98
First, get behind the lip of the cheek cowl inlets and make sure to thin them out with a sander so the inlets slip on the cowl lips nice. Final inlet fitting and gluing comes later.
Then glue the cheek cowls on. I use a similar method with masking tape and alternating toothpicks on both sides of the joint, Tim Redelman taught me that one. Don't let any voids get in the glue joint or it will show up when you sand the joint out later.
After you get the cowls on and before you sand the outside of the joint, go inside and clean the joint with a drum sander. Flatten it out. Then glass in a couple of layers of 6 ounce cloth over the joint. These cowls will crack if you don't reinforce it and you fly hard. Also, it helps strengthen the joint when you block sand the outside of the joint later. It can get wavy otherwise.
Now deal with the inlets. You need a strong glue joint to the cheek cowl lips. You have to sand the inlet lips to get a good fit.
Roger has the idea with the fin bolt. You absolutely need it 100%.i even add a former in the front to bolt the fin to. In a bandit, the fin will flutter first
Then glue the cheek cowls on. I use a similar method with masking tape and alternating toothpicks on both sides of the joint, Tim Redelman taught me that one. Don't let any voids get in the glue joint or it will show up when you sand the joint out later.
After you get the cowls on and before you sand the outside of the joint, go inside and clean the joint with a drum sander. Flatten it out. Then glass in a couple of layers of 6 ounce cloth over the joint. These cowls will crack if you don't reinforce it and you fly hard. Also, it helps strengthen the joint when you block sand the outside of the joint later. It can get wavy otherwise.
Now deal with the inlets. You need a strong glue joint to the cheek cowl lips. You have to sand the inlet lips to get a good fit.
Roger has the idea with the fin bolt. You absolutely need it 100%.i even add a former in the front to bolt the fin to. In a bandit, the fin will flutter first
Last edited by mr_matt; 02-19-2018 at 11:20 AM.
02-19-2018, 06:25 PM
#99
All good info from Matt. Especially the the "masking tape and alternating tooth picks" method. This does great job when aligning two surfaces to be glued. If you don't understand what we mean, let me know and I will attempt to explain.
02-19-2018, 06:50 PM
#100
Yes please explain, is it like the tape and balsa method in the f4 thread? I noticed that my cowls have to be "shaped to" the fuse, almost as if they are slightly too big. They are kinda springy. You can push them past the fuse seem so they are too deep. So the balsa method seemed to be a good way to ensure they are flush. I assumed Id use tape and probably have to fill and sand.
There are so many things I should have learned before building this jet thats for sure. Its like taking a car engine apart without knowing what a wrench is. So I appreciate the help.
When I read the instructions I guess they assume Im not completely ignorant. I would expect that if the instructions have me trial fit everything, they would then tell me to make some marks on the cowls and fuse and disassemble. That way I can glue the cowls on and line up the marks. It just skips that part and talks about gluing the cowls on. Obvious in retrospect but better safe than sorry.
I ordered some pinhole filler and my engine mount for the bypass today. So moving forward. Will it fly this summer?????
There are so many things I should have learned before building this jet thats for sure. Its like taking a car engine apart without knowing what a wrench is. So I appreciate the help.
When I read the instructions I guess they assume Im not completely ignorant. I would expect that if the instructions have me trial fit everything, they would then tell me to make some marks on the cowls and fuse and disassemble. That way I can glue the cowls on and line up the marks. It just skips that part and talks about gluing the cowls on. Obvious in retrospect but better safe than sorry.
I ordered some pinhole filler and my engine mount for the bypass today. So moving forward. Will it fly this summer?????