ESM Dornier DO 335
05-01-2013, 09:54 AM
#727
RE: ESM Dornier DO 335
I do believe I stated I ordered another set of batteries. I hadn't done so prior just in case disaster happened. Common sense I thlnk. I also do have two 12v deep cycle marine batteries and two chargers for field use.
As for jot being able to fly the plane again last Sunday, its a good thing. Esc needed to be reprogrammed and would have been stupid to try to fly it again that day till the problems were investigatedm.
As for jot being able to fly the plane again last Sunday, its a good thing. Esc needed to be reprogrammed and would have been stupid to try to fly it again that day till the problems were investigatedm.
06-04-2013, 07:21 PM
#728
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RE: ESM Dornier DO 335
Hi Guys,
Well, I hope the lack of news from Kahloq means that he is busy flying his Dornier.
I've now acquired most of the bits for mine and have started bolting them on. I'm going to see how the balance looks with the engines mounted as per the instructions, eg no rear shaft, and see how it looks for balance. If it needs a ton of lead up front I will reconsider. However, that leads us to the first snag. The rear bulkhead is not mounted squarely. It is 3.5mm (just over 1/8") off vertical, and 5.25mm off sideways. (Just over 3/16"). I don't think this can be meant to provide sidethrust, and if it is it seems excessive. Also the downthrust component would be wrong, you would want upthrust on this engine to provide the equivalent of downthrust on the front. So I think what has happened is that someone at the factory glued the bulkhead in the wrong position, leaving me with an interesting problem. I need to build up the existing bulkhead to provide a surface that is in the correct plane. I have some space to do this, since the radial type engine mount needs packing out by nearly half an inch anyway.
John
Well, I hope the lack of news from Kahloq means that he is busy flying his Dornier.
I've now acquired most of the bits for mine and have started bolting them on. I'm going to see how the balance looks with the engines mounted as per the instructions, eg no rear shaft, and see how it looks for balance. If it needs a ton of lead up front I will reconsider. However, that leads us to the first snag. The rear bulkhead is not mounted squarely. It is 3.5mm (just over 1/8") off vertical, and 5.25mm off sideways. (Just over 3/16"). I don't think this can be meant to provide sidethrust, and if it is it seems excessive. Also the downthrust component would be wrong, you would want upthrust on this engine to provide the equivalent of downthrust on the front. So I think what has happened is that someone at the factory glued the bulkhead in the wrong position, leaving me with an interesting problem. I need to build up the existing bulkhead to provide a surface that is in the correct plane. I have some space to do this, since the radial type engine mount needs packing out by nearly half an inch anyway.
John
06-04-2013, 10:00 PM
#729
RE: ESM Dornier DO 335
ORIGINAL: kahloq
Will it still do that if its not CCW rotation?
Will it still do that if its not CCW rotation?
Put it the same way, as well.
If the motor goes the wrong way, interchange two wires. Problem solved.
06-05-2013, 07:20 AM
#731
RE: ESM Dornier DO 335
ORIGINAL: kahloq
Don't have the same motor front and back...so can't use the same prop on mine. Not going to change them either.
Don't have the same motor front and back...so can't use the same prop on mine. Not going to change them either.
06-05-2013, 08:34 PM
#733
RE: ESM Dornier DO 335
When is this beast gonna fly again?
I think the point is with electric power, tractor or pusher props can be used on the rear as all that is needed is to change the rotation of the motor. This has been hashed out earlier I believe.
Tractor props are certainly easier to come by.
I think the point is with electric power, tractor or pusher props can be used on the rear as all that is needed is to change the rotation of the motor. This has been hashed out earlier I believe.
Tractor props are certainly easier to come by.
06-05-2013, 09:02 PM
#736
RE: ESM Dornier DO 335
ORIGINAL: vertical grimmace
When is this beast gonna fly again?
I think the point is with electric power, tractor or pusher props can be used on the rear as all that is needed is to change the rotation of the motor. This has been hashed out earlier I believe.
Tractor props are certainly easier to come by.
When is this beast gonna fly again?
I think the point is with electric power, tractor or pusher props can be used on the rear as all that is needed is to change the rotation of the motor. This has been hashed out earlier I believe.
Tractor props are certainly easier to come by.
The plane will fly this way....but will fly better with props rotating in the opposite direction. I tested both ways on my ESM Dornier 335 last year running two Eflite 160s with 20x10 props. Roll rates left and right were slightly different with props spinning in the same direction. Trim was slightly different as plane pulled a bit. Not a deal breaker, just something to watch out for. The full scale had props swinging in the opposite direction I believe. The Germans must have known something.
But I agree...the pushers are hard to come by in that size. These folks are a fantastic source. http://shopbobshobbycenter.com/index.html
06-06-2013, 10:28 PM
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RE: ESM Dornier DO 335
Part of the ingenuity of the original design by Dornier was that they could use a pair of identical engines, eg not a handed pair like a normal twin would have. This gives opposite rotation as seen from the front, and needs a pusher propellor. It also makes maintenance easier, eg spare engines are all the same. Luckily they never got enough into service for that to matter anyway. With both engines going the torque reactions cancel out. If one fails there is no assymetrical thrust and only a normal amount of torque reaction, which will be left for one of the engines and right for the other.
For a model I am not sure that this is too important. We are not overpowering our models quite so much as the full size.So although the counter rotating props would be nice to have, if the pusher one is not readily available I wouldn't worry, at least for the electric guys. Torque effects should be no worse than if a single engine in the front is providing all the power. Of course with IC engines reversing the direction is not such an easy option.
I asked a while back if anyone knew what all the servos were supposed to be for. Having studied the comic book in more detail I have now figured it out. They are allowing for an ignition switch servo for the front engine, and when you add the rear engine, that gets one too. This is despite the fact that in the little picture the rear engine looks rather like a glow fourstroke. Anyway, these days, I would suggest that rather than using a servo to push a switch, one should use one of those little optically coupled switches made for the job...lighter than a servo and switch, and less prone to failure from vibration.
John
For a model I am not sure that this is too important. We are not overpowering our models quite so much as the full size.So although the counter rotating props would be nice to have, if the pusher one is not readily available I wouldn't worry, at least for the electric guys. Torque effects should be no worse than if a single engine in the front is providing all the power. Of course with IC engines reversing the direction is not such an easy option.
I asked a while back if anyone knew what all the servos were supposed to be for. Having studied the comic book in more detail I have now figured it out. They are allowing for an ignition switch servo for the front engine, and when you add the rear engine, that gets one too. This is despite the fact that in the little picture the rear engine looks rather like a glow fourstroke. Anyway, these days, I would suggest that rather than using a servo to push a switch, one should use one of those little optically coupled switches made for the job...lighter than a servo and switch, and less prone to failure from vibration.
John
06-07-2013, 12:23 AM
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RE: ESM Dornier DO 335
I've solved my problem with the bulkhead, Iglued on a piece of 16mm ply and then used a router against the rear of the fuselage to plane it back to be parallel. Now Ihave a surface to bolt my engine to that will not give me large amounts of side and downthrust.
John
John
06-07-2013, 05:32 AM
#739
RE: ESM Dornier DO 335
ORIGINAL: Ameisenbar
I've solved my problem with the bulkhead, I glued on a piece of 16mm ply and then used a router against the rear of the fuselage to plane it back to be parallel. Now I have a surface to bolt my engine to that will not give me large amounts of side and downthrust.
John
I've solved my problem with the bulkhead, I glued on a piece of 16mm ply and then used a router against the rear of the fuselage to plane it back to be parallel. Now I have a surface to bolt my engine to that will not give me large amounts of side and downthrust.
John
Nice job on the routing...that sounds difficult. How did you rout the bulkhead with the right angles and get it even all the way across? CNC machine?
I would have just popped the bulkhead off and reset it. Chinese glue is not always the best. In fact, I added extra epoxy to all my key bulkheads.
best,
jim
06-07-2013, 06:13 AM
#740
RE: ESM Dornier DO 335
ORIGINAL: Ameisenbar
Part of the ingenuity of the original design by Dornier was that they could use a pair of identical engines, eg not a handed pair like a normal twin would have. This gives opposite rotation as seen from the front, and needs a pusher propellor. It also makes maintenance easier, eg spare engines are all the same. Luckily they never got enough into service for that to matter anyway. With both engines going the torque reactions cancel out. If one fails there is no assymetrical thrust and only a normal amount of torque reaction, which will be left for one of the engines and right for the other.
For a model I am not sure that this is too important. We are not overpowering our models quite so much as the full size.So although the counter rotating props would be nice to have, if the pusher one is not readily available I wouldn't worry, at least for the electric guys. Torque effects should be no worse than if a single engine in the front is providing all the power. Of course with IC engines reversing the direction is not such an easy option.
I asked a while back if anyone knew what all the servos were supposed to be for. Having studied the comic book in more detail I have now figured it out. They are allowing for an ignition switch servo for the front engine, and when you add the rear engine, that gets one too. This is despite the fact that in the little picture the rear engine looks rather like a glow fourstroke. Anyway, these days, I would suggest that rather than using a servo to push a switch, one should use one of those little optically coupled switches made for the job...lighter than a servo and switch, and less prone to failure from vibration.
John
Part of the ingenuity of the original design by Dornier was that they could use a pair of identical engines, eg not a handed pair like a normal twin would have. This gives opposite rotation as seen from the front, and needs a pusher propellor. It also makes maintenance easier, eg spare engines are all the same. Luckily they never got enough into service for that to matter anyway. With both engines going the torque reactions cancel out. If one fails there is no assymetrical thrust and only a normal amount of torque reaction, which will be left for one of the engines and right for the other.
For a model I am not sure that this is too important. We are not overpowering our models quite so much as the full size.So although the counter rotating props would be nice to have, if the pusher one is not readily available I wouldn't worry, at least for the electric guys. Torque effects should be no worse than if a single engine in the front is providing all the power. Of course with IC engines reversing the direction is not such an easy option.
I asked a while back if anyone knew what all the servos were supposed to be for. Having studied the comic book in more detail I have now figured it out. They are allowing for an ignition switch servo for the front engine, and when you add the rear engine, that gets one too. This is despite the fact that in the little picture the rear engine looks rather like a glow fourstroke. Anyway, these days, I would suggest that rather than using a servo to push a switch, one should use one of those little optically coupled switches made for the job...lighter than a servo and switch, and less prone to failure from vibration.
John
Well first of all, with a centerline thrust aircraft you can never have an assymetric thrust if one engine is out due to fact that the engines are on the same thrust line.
Second, you REALLY think our models are less overpowered than their full size counterparts!? LOL, first i have ever heard someone say that. Most all of our models have a near 1:1 thrust to weight ratios, very few MODERN jets as capable of that feat, and the DO335 if it was stripped down to nothing might have a .5:1 thrust/weight ratio. Our models are insanely overpowered for their sizes, if we used the same thrust to weight ratios as their real counterparts, we would be flying 60size models with 40 size engines, possibly smaller.
06-07-2013, 03:52 PM
#741
RE: ESM Dornier DO 335
Agreed, most RC aircraft fly on the "prop" and not on the "wing" like most full scale aircraft. The only exceptions might be some of the newer aerobatic planes.
I find it interesting on the prop rotation though. I am sure there is an optimum rotation direction. This would be important for an engine powered version if optimal performance was sought. this along with correct prop as well. If both engines were spinning the right direction and with the best props, it would be interesting to see what this plane could do? I can almost guarantee the best props would not be 3 blade. For me on this plane a DLE 55 RE and a DLE 35 RE would be the ticket. What a fun project. Unfortunately, the budget does not allow for such endeavors.
I find it interesting on the prop rotation though. I am sure there is an optimum rotation direction. This would be important for an engine powered version if optimal performance was sought. this along with correct prop as well. If both engines were spinning the right direction and with the best props, it would be interesting to see what this plane could do? I can almost guarantee the best props would not be 3 blade. For me on this plane a DLE 55 RE and a DLE 35 RE would be the ticket. What a fun project. Unfortunately, the budget does not allow for such endeavors.
06-09-2013, 03:05 PM
#742
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RE: ESM Dornier DO 335
"Well first of all, with a centerline thrust aircraft you can never have an assymetric thrust if one engine is out due to fact that the engines are on the same thrust line. "
Well first of all Isaid that one of the advantages of the design was that you did not get assymetrical thrust if one engine was out, so your remark adds nothing new. There are other advantages to the design too, for instance the frontal area is about the same as that of a single engine fighter, while having two engines to give twice the power.
"Second, you REALLY think our models are less overpowered than their full size counterparts!? LOL, first i have ever heard someone say that. Most all of our models have a near 1:1 thrust to weight ratios, very few MODERN jets as capable of that feat, and the DO335 if it was stripped down to nothing might have a .5:1 thrust/weight ratio. Our models are insanely overpowered for their sizes, if we used the same thrust to weight ratios as their real counterparts, we would be flying 60size models with 40 size engines, possibly smaller."
Second, thrust is not power. Thrust is a force, power is a rate of doing work. You can get a lot of thrust from a hydraulic jack, without needing a lot of power to do it. But what Iwas getting at was that the combination of high power and high wing loading in the full size aircraft, warbirds in particular, makes them pretty much a handful to control. This is why models tend to be tamed down a bit, eg lower wing loadings, less sheer power, larger tail surfaces. The full size Do 335 had 3500 horsepower available on takeoff. How would that scale down to a model size do you think?
06-09-2013, 03:16 PM
#743
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RE: ESM Dornier DO 335
Jimkron, what I did with the routing is that I glued a piece of 5/8" ply to the firewall, then stood the plan on end in a stairwell here, with my adult son holding it vertical tail up. My wife held a small halogen lamp to illuminate the working area as much as possible. Then using a router bit with a longish plain shank I sat the router on the flat end of the fuselage. The glass here is turned in like a flange and makes a good flat surface. So with light cuts and a lot of care I was able to cut back the top surface of the added piece so that it is parallel to the end of the fuselage. I had to make sure I didn't allow the router to tip at all since that would have let the cutter go through the side of the fuselage. The plain shank meant that the cutter would not cut the edge of the flange when working out towards the sides. It was more difficult in contemplation than in execution.
I didn't try to remove the bulkhead to reglue it since for once an ARTF has lots of glue where it is needed. Actually they have made a fillet with a strip of glass cloth set in it, so getting it out would be a bit tricky. It is glued in at least as well as I would have done it. I hope all the otehr bits are glued as well.
John
I didn't try to remove the bulkhead to reglue it since for once an ARTF has lots of glue where it is needed. Actually they have made a fillet with a strip of glass cloth set in it, so getting it out would be a bit tricky. It is glued in at least as well as I would have done it. I hope all the otehr bits are glued as well.
John
09-19-2013, 09:38 AM
#744
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Hello:
I know this was discussed earlier in this thread, and there was some back and forth about where the CG should be.
For all of you who have actually flown your ESM Dorniers, where did you end up with best spot for the CG? Please let me know if this was with gear up or gear down (obviously, the CG moves back when the nose gear goes up)
Thanks,
Brian
I know this was discussed earlier in this thread, and there was some back and forth about where the CG should be.
For all of you who have actually flown your ESM Dorniers, where did you end up with best spot for the CG? Please let me know if this was with gear up or gear down (obviously, the CG moves back when the nose gear goes up)
Thanks,
Brian
09-28-2013, 03:07 PM
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Hello Boltman , Just a not of interest , , on the factory type drawings by AL Bently ,, the sub rudder has a steel skid attached to a shock absorbing strut on he front portion of the sub rudder.
JIM
JIM
12-07-2013, 12:33 PM
#747
I just picked a 335 up for a steal. Has anyone attempted an extension shaft to move the rear motor closer to the c.g.? I'm going electric and I'm thinking have a few bulkheads with bearings in them to support the shaft.
Also, anyone know if Sierra is still making retracts for it? Thanks!
Also, anyone know if Sierra is still making retracts for it? Thanks!
12-07-2013, 03:05 PM
#748
Yes Sierra makes gear for it...check VQwarbirds.com
Since your going electric.....there is no point in trying to use an extension shaft. You're only going to complicate things and add a point of failure....plus that shaft with bearing just adds weight.
This plane has been built and flown successfully with two power 160 class motors front and rear on 10s(AUW 32 pounds) as well as my setup of a big 65cc rimfire(12s) up front for the grunt work and a power 60(6s + lighter then a power 160) at the tail to basically just spin a decent size prop(AUW 37 pounds).
Since your going electric.....there is no point in trying to use an extension shaft. You're only going to complicate things and add a point of failure....plus that shaft with bearing just adds weight.
This plane has been built and flown successfully with two power 160 class motors front and rear on 10s(AUW 32 pounds) as well as my setup of a big 65cc rimfire(12s) up front for the grunt work and a power 60(6s + lighter then a power 160) at the tail to basically just spin a decent size prop(AUW 37 pounds).