SR Batts Eindekker - any tips?
 

Big box full of bits finally arrived:D Also have G26 ready to fit. Since a few of you guys have built one of these now, I was hoping to hear of any build mods you would suggest before I start gluing. Kit looks great, but I recall a few comments re U/C springing and flying wire anchors in other threads. Also, anyone have a web address for 1/4 scale WW1 instruments?

Thanks,

Cam

RE: SR Batts Eindekker - any tips?
 

Hey Cam, good luck on your build. I have some tips that can save you some grief and time. Minor mishaps caused by engine failures on take offs showed me some weaknesses in SR's design that can be rectified with very little work. Most of the problems were in their design of the rigging attachment blocks. My first problem happened during taxi trials when the tire cam into contact with the flying wire and it was pulled out of the wing Block and all. The obvious solution was to tighten the bungee. It helped until a stronger impact occured. Ultimately a complete rebuild of one of the wings has lead up to these modifications.
1) attachment blocks should be tied into the spars. I have wired mine through the blocks and around the spars plus used strips of super coverite around the blocks. These strips are in front and behind the spars. They begin on the rib, go over it around the blocks and are attached back onto the rib. A third strip goes around both blocks in the other direction effectivly making a cacoon. Another solution would be to use a solid block of wood (replacing their block)and simply drill a hole the size of the spar and slide it on during your build. If your blocks attach to the ply ribs you should double the rib or at least stregthen it in addition to tying it into the spar. My improvement has prooved it's worth by actually surviving other minor mishaps where the wire has been grabbed and ended up behind the tire. The whole wing was warpped and I needed to unscrew the fitting to release the tension.

2) Add webbing to the front spar between the false ribs with a 1/4" cap.

3) I reinforsed all the balsa ribs with 1' square patches of coverite over the holes on both sides of the ribs. In the event of a minor accident, if the wing come into contact with the ground, the wing tip will transfer the impact along the trailing edge. This will jamb the base rib up against the fuselage. It will not give nor will the spars. What will happen is that the force will absorbed along the TE and it will break and all of the ribs between the base rib and the aileron will be forced from the spar. These will not be clean breaks and will be difficult to repair. These patches may help reduce the damage to the ribs. A mishap of this sort now, would possibly cause the ribs to break in this area but remain intact because of the coverite.

4) Add wood fairings to the landing gear. These add strenght as well as make it appear more scale. Currently mine are basswood but will be replaced with a harder wood.

5) Add turnbuckles to your rigging. Any minor mishap will effect your landing gear to some extent and will also effect your rigging ( because your flying wire are attached to the landing gear) Turnbuckle can save you time and effort as well as wire. I use Dubro turnbuckles on the flying wires and adjustable clevises on the landing wires. This necessitated my next modification.

6) I made a brass plate to replace SR's attachment setup on the upper pylon. My plate is 1/8" brass with 4 holes to accept the clevises and a slot which slips over the top of the pylon. This not only allows me to adjust the landing wires but subtracts abut 5 minutes from set up and breakdown times. I now slip my wings on, attach the flying wires, (the turnbuckles are already safety wired so they just slip on and get bolted on) I than attach only one side of the landing wires to the brass plate( the other side is already attached) and than lift ( or stretch) the brass plate onto the pylon. This is than wired onto the pylon for safety. I can not see how this would come off however unless both sets of landing wires on one side were removed.

6) use heavy bungee on your gear. See picture

RE: SR Batts Eindekker - any tips?
 

Sorry for the LARGE pic but it shows the details of the landing gear. Now if i could only figure out how I did that.:)

BTW another mod I made was adding a brass collar to the tip of the tail skid. Without it the plane just seemed to wander off the runway. If you have any questions just post them here.

RE: SR Batts Eindekker - any tips?
 

Thanks for all the info Feep. Do you have any shots of how you did your tailplane mounting and construction? Certainly adds to the scale effect.

I'm not going to worry about fuz length etc, just want the "look" to be right. Ailerons stay!:D

Thanks again for all your help,

Merry Christmas,

Cam

RE: SR Batts Eindekker - any tips?
 

I have no shots of the elevator build but I have plans I drew up. I will see if I can scan them for you. Basically I did the scale outline from drawings I have, and then took the carbon fiber rods to determine the thickness. I used the leading edge rod for the hinge piece. I wanted to make the whole elevator as one piece so it needed to extend from one side to the other. That way I could attach it to the rear of the fuselage with metal straps as in the full scale. I used the TE carbon fiber rods for the leading edge and 1/4 " dowel for the TE. I used the rear ply sides and filled in the slot. This was done because I was not sure my elevator would work and it would allow me to return to the original plan. IT DOES WORK and if I was going to do it again I would remove the ply sides and just keep the top portion which accepts the rudder post. As it was the rear of the fuselage as built, had a built in slot for the elevator hinge and so I just filled in part of it to simply accept the elevator. Only the pull-pull line held it to the rear of the fuselage.
One of my mishaps caused the elevator hinge rod to break right at the edge of the fuselage. I decieded to make the elevator in 2 pieces rather than join the 2 halves again. Now I have a brass tube along the rear of the fuselage which holds the elevator halves. Originaly I used the control horns from the kit for the elevator and the rudder. As designed, I don't think there would be a problem but the way I incorporated them I had inadvertently put a lot of negative ackerman into the elevator. It would porpoise at high speed when in neutral. At the field a lot of us took a closer look and saw that one line would go slack as the other pulled and tightening the line seemed to do no good and in fact only cased the elevator to bind. It wasn't until I read a thread on ackerman that I came to realize the problem. I ran down to my workshop and measured the distance from the control horn attachment point ot the middle of the hinge line and it was about 5/8 of an inch behind.This cause it to porpoise but only when the elevator was in the neutral position. With up or down the forward portion of the elevator was helped by the airflow. I fly my eindecker slow and scale and the porpoising problem did not happen that often but it unnerved me enough that I was just about ready to ground it when I discovered the problem. I solved the problem by making my own control horns from brass and as we speak, I have ironed out all the problems with the eindecker and can now concentrate on adding details.My winter project involves remarking it like "509" which had spoked wheels.

RE: SR Batts Eindekker - any tips?
 

Thanks Feep - those photos are pretty self-explantory. I think I'll copy your tailplane mounting if you don't mind;) - the horn geometry has always been a hobby-horse of mine, so I see what you mean. I'll incorporate glassed ply horns into my tailplane build.
Other mods sound pretty straightforward - the anchor points etc will certainly be tied into the structure as suggested, and bungee cord beefed up etc.
Did you find it all built straight as per the instructions - I'm sure Larry knows what he's doing, it just sounds weird the way it's all done, especially the wings. I'm a "pin the trailing edge to the board" kind of guy:)
Thanks again,

Cam

RE: SR Batts Eindekker - any tips?
 

This was my third kit build since I've returned to this hobby. I have been involved in modeling for 30 or more years and have even done some static kit manufacturing. I built some kits back in the 70's but got out of RC until about 4 years ago.
Yes I built it straight as per, but my mods were from what I lerned from the crashes I've had. The wings are certainly different the way they build, but they work.
I will take some measurements soon but one advantage to putting the elevator at the end of the fuselage is that it adds about 3'' to the overall length and makes it look more Elll ish. I'm not sure if the extra full scale foot between the E1 and Elll is overall or actally in the fuselage. I suspect fokker had an extra bay added to the fuselage to balance it because of the larger engine.
I'm flattered that you would copy my ideas. I thought of ways to incorporate the horns right onto the hinge rod but I was unwilling to glue them to the carbon fiber rods. I just would not trust a glue joint on something so critical and drilling into the rod made me uneasy also. If I could do it over I would perhaps remove the ply at the rear and use the saved weight to incorporate steel tubing or brass and weld or solder the horns right to the hinge. That would solve the ackerman problem and make it more scale like.
Maybe it's only me but when you take somone elsesdesig an start tampering with it you have to ask yourself what were they thinking and what do they know that I don't?

RE: SR Batts Eindekker - any tips?
 

Like "what were they thinking putting THREE machine guns on the front of some of these"! Interrupter gears or not, I'm sure it was no consolation to Max Immelmann as he followed his splintered prop down.....[:@]

Having seen how some ARTF's are built, I have absolute faith in our commonsense as "real" modellers. Also, years flying R/C gliders in competition taught me the structural limits of just about every building material there is.:D Very useful.

I still cringe when I see transversely-mounted aileron and elevator servos on big fast R/C models, not to mention plastic clevises and thoze evil EZ connectors with grub screws...........(gets off soapbox)......

Where was I? Oh yeah, turns out the hardware pack had gone AWOL in my kit so Larry's sending out a replacement. Should give me time to clear a BIG area on the workbench. Have to pick a nice EIII scheme now.

Cheers,

Cam

RE: SR Batts Eindekker - any tips?
 

I did some measurements on my eindecker. Actually, as I was measuring it , it occured to me that moving the elevator back doesn't make the model any longer! The rudder is still where it is and it's the furthest point back. Moving the elevator does make it appear a little less "stunted" ?:eek: My overall is 68 inches which is 3'' short in 1/4 scale. So a rebuild of the elevator doesn't make it any more scale it just makes it appear that way. Of course there is always the challange:D But take the farmer, dress him up in a suit and tie with a fancy hankerchief in his pocket and a flower in his button hole and what do you have? :D A SOIL AND VEGITATION ENGINEER! :D

RE: SR Batts Eindekker - any tips?
 

Yes look at http://www.airfieldmodels.com
Paul just built one, look at whats new...

RE: SR Batts Eindekker - any tips?
 

thanks Iron E. - thats a very good site. Where do these guys find the time???

RE: SR Batts Eindekker - any tips?
 

A lot of guys are retired, or drink a lot of coffee and stay up late. I am of the drink coffee and stay up late crowd. Beats watching tv, by a long shot. Plus, with the winters up here you have plenty of time to do things indoors

RE: SR Batts Eindekker - any tips?
 

Hey Iron Eagle, we're neighbors! Yea you have to take the weather and make it work for you. I'd rather be flying but since I have to live with it, I ski in it. The down time also gives you a chance to recoup from the flying season.

RE: SR Batts Eindekker - any tips?
 

Feep,
Like your icon....
Thought I saw one of you guys in New Mexico.......
I tried skiing years ago, of couse I could not do the beginers slope, place called Wildcat, big mistake. When I finaly made it down was greatful to be alive, have not tried since. Have you looked at the airfield models site?
Going up to NH Sunday, have to drop by a friends house in Greenfield, then up to Mount Vernon. Love it up in NH want to move up there and do some farming myself. Of course I will have to have enough flat space for a runway too!

RE: SR Batts Eindekker - any tips?
 

Yes I have been on his site and he has another thread about the SR eindecker. This has been a fun project but I won't tell you my knees haven't been knockin a few times. Over all I was surprised how little the full flying elevator changed the way it flew. That is not to say I flew it in it's original configuration but there really haven't been a lot of surprises. I knew ahead of time that the elevator would be sensative but it caught me off guard just how much.

I'm really a blow in from Mass. and I live right on the boarder near Lowell. I fly with the 495th. Ever been up here?

RE: SR Batts Eindekker - any tips?
 

Hey Feep, am I correct in assuming your rudder and tailplanes are only held in place by the control cable tension? Also, do you now have carbon rods from each tailplane 1/2 meeting in the middle of that brass tube?

I was considering using a longer rod across the fuse that the tailplanes slide onto, ala gliders, as I'm concerned whether that brass tube could buckle in the centre, especially if the tailplanes are allowed to creep apart a bit.

For the flying wire blocks, I think I'll thread solid blocks onto the spar tubes and glue to the ribs - touch heavier but WAY stronger.

Cheers,

Cam

p.s. We back onto the "southern alps" here - short drive to ski resorts. I used to ski alot - we have a share in a lodge - but have since discovered Paragliding and now spend more time flying over them than skiing them:D

RE: SR Batts Eindekker - any tips?
 

Oh wait, I think I figured it out! Your brass tube extends into the tailplane 1/2's doesn't it - doh!:eek:

RE: SR Batts Eindekker - any tips?
 

No you were right the first time. The carbon rods meet half way into the brass rod which is attached across the back of the fuselage.
Yes they are only held in place by the control lines. That is the way SR designed the rudder. I know it sounds a little unothordox but it works. If you go on the Airfields.com web site and watch the video you can hear them ask if the rudder came off so I guess it has more than just you wondering. What are your thoughts on this?

RE: SR Batts Eindekker - any tips?
 

Just been in the workshop sketching out the tailplanes and making a shopping list. I think I'll go with the carbon tube spar/pivot idea too, but I DON'T think relying on the brass tube as a joiner is the way to go!

Your setup, if the tailplanes crept out a bit, has only a hollow metal tube to resist all the bending loads - bit dodgy if you ask me. I'd consider putting a solid carbon rod inside your tubes - stuck in one side maybe - so you have a stronger "spar" joining them. Then it wouldn't matter if they creep apart a bit.

I'll probably have a carbon rod mounted across the rear fuz., maybe covered with metal tube/straps where visible, then slide the tailplanes onto the rod. Shame to waste all the kit ribs etc., but will use full-chord ones drilled for the tube spar instead.

No other major mods, just the blocks for flying/landing wires, and modify the rear of the top hatch to put an instrument panel in.

Cheers,

Cam

Off to the "big smoke" tomorrow to get some bits.

RE: SR Batts Eindekker - any tips?
 

Well Cam, I never looked at that aspect of the setup. Actually the rudder would creep up a little (!/4) but no big deal and as I said earlier the elevator was originally designed as one piece. I could have built it from the beginning with the second tube over the hinge but I never thought of it. This set up isthe result of the unit breaking after a mishap. Right now the rudder and elevator do not move laterally. I will be looking at that brass tube and it stresses. What has been bothering me is the attachments to the control horns. I have adjustable clevises and the have the rubber safeties but I think I am going to replace them with something that gives me more piece of mind.
I beleive I used balsa ribs that were the next size up from the carbon tube and I put ply on both sides of the hole in the rib for strength. I'll see if I can reduce the drawings I did later today and post them.

RE: SR Batts Eindekker - any tips?
 

Cam, I know a carbon fiber tube is stronger than a carbon fiber rod of the same diameter. If I take a 1/4'' tube and insert the next size down and take another tube the next size down until it is almost solid does that it become stronger because it's made of plys or does it start to act as though it's solid? I think I already know the answer but it can't hurt to ask. The more I think about it the more it seems that it should get stronger.

If thats's the case than the vibration and flex I have noticed with the elevator can be solved by using multiple tubes in the hinge spar to increase strenght

RE: SR Batts Eindekker - any tips?
 

The 1/4 inch carbon fiber tube should be more than strong enough by itself for spans less than 24 inches. That should be more than long enough to act as spar and joiner even for a flying elevator set up.
I am not sure the bearing arangment would work in this aplication but how about this?
Take two small pieces of aluminum stock, the first about 3/4 of an inch long, 1/4 inch thick, and 3/8 inch wide. The second 1/2 inch long, 1/4 inch thick, and 3/8 inch wide. Center the 1/2" piece over the 3/4" drill a hole, 1/8 of an inch in from the end of the 1/2" through both it and the 3/4" piece so you can tap the 3/4 inch piece to take a # 2 bolt. Enlarge the hole in the 1/2 piece that the bolt just passes through it. Now bolt the two blocks together drill a hole on the center of the seam between the two blocks around 9/32". Now you have a 2-piece block that you can use for a bearing for the carbon fiber rod. Drill a hole in each end of the 3/4 inch piece so you can mount it to the fuselage.

RE: SR Batts Eindekker - any tips?
 

Feep - When I first realized that the rudder is held on by the control wires it concerned me. But I couldn't think of any reason why it wouldn't work and the SR manual says it works fine. I'm sure if people were losing their rudders the design would either change fast or you would being hearing about it from people who took the time to build the model and then have it crash because of an inherent design flaw!

By the time we were ready for the maiden flight, there were no real concerns about the rudder sliding off. That's me asking about it in the video and Mike responding, but the question was meant to be tongue in cheek.

RE: SR Batts Eindekker - any tips?
 

By the way, I'm not positive about this, but I'm pretty sure that a rod is stronger than a tube of equal diameter and of the same material. What makes a tube better than a rod is that it has a higher strength to weight ratio, but I think in terms of brute strength the rod will always be stronger.

RE: SR Batts Eindekker - any tips?
 

Paul, I used a very untechnical term. I meant that a rod was more flexible than a tube. This is dangerous ground for you. I was actually thinking out loud and looking inside my mind is probably not a pretty sight. :Dg What I was thinking was that if you used a 1/4' tube for the hinge spar and than used the next size down to slip inside, that would act like a ply and make the spar less flexible.

I kinda thought you guys were refering to a sort of private joke but nevertheless Im' guessing the rudder design raised an eyebrow.

Cam here arte my drawings for my elevator. real simple.