DH 2
06-27-2015, 05:55 AM
#379
10-14-2016, 04:13 PM
#386
10-15-2016, 02:51 PM
#387
Greg I sent you an PM, and yes I might be interested in getting a set of plans to look over...I like to roll them out and see what I need to get things together.. And you know how it is..one day you just start cutting /gluing parts !
10-17-2016, 07:28 PM
#388
I had to share this new video uploaded on youtube.. It has in cockpit footage from a DH2 ...what an amazing feeling it would be to fly from that pod...
https://www.youtube.com/watch?v=phhICN7GY9E
https://www.youtube.com/watch?v=phhICN7GY9E
12-03-2016, 05:00 AM
#390
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Maybe, just maybe, it might be easier to get DH-2s in the air.
The DH-2 has always interested me. Now with my 1910 Curtiss Hudson Flier and AVRO Triplane projects (almost) behind me, I thought it would be great to do a next project that would have a broader appeal and maybe even kittable. I've started on the design and have even had some conversations with a kit company with the idea that they might carry this as a kit.
Here are some very preliminary CAD illustrations. The design has progressed from there and there is still lots more to do but I am feeling pretty good that a 1/4 scale kit can be designed for a manageable build without too many non-scale compromises. We'll see.Sorry for the intrusion. Great work R/C Art and congratulations on a magnificent project!
The DH-2 has always interested me. Now with my 1910 Curtiss Hudson Flier and AVRO Triplane projects (almost) behind me, I thought it would be great to do a next project that would have a broader appeal and maybe even kittable. I've started on the design and have even had some conversations with a kit company with the idea that they might carry this as a kit.
Here are some very preliminary CAD illustrations. The design has progressed from there and there is still lots more to do but I am feeling pretty good that a 1/4 scale kit can be designed for a manageable build without too many non-scale compromises. We'll see.Sorry for the intrusion. Great work R/C Art and congratulations on a magnificent project!
12-03-2016, 07:13 AM
#392
Chevelle,
That would be really cool to see a DH2 kit in 1/4 scale. After building mine from plans, I'm convinced it is a "kittable" airplane at least for the experienced builder. There were only a few areas where the engineering or construction was a bit more work than a simpler WWI kit:
- the fiberglass nose cap made from scratch
- engineering the connections at each end of the tail struts, plus getting the tail and tail strut alignment setup correctly. I made mine out of carbon fiber tubes which made engineering the connections a little more difficult. I had to make custom fittings that could be epoxied into the tubes & then used steel straps to bolt them to the air-frame on each end. Wood tail struts would be a lot easier to connect, but I wanted to minimize tail weight.
- integration of pulleys into the pull-pull systems. I think the pulley blocks one can get from a model sailboat supplier work well for a quarter scale DH2. Using these made life simple for me. My definition of "well" is high-reliability (at the expense of probably not looking exactly scale). This is what I used on mine.
Not that any of the above were impossible, just a bit more work & engineering than a simpler kit would require.
best of luck on your DH2!
Greg
That would be really cool to see a DH2 kit in 1/4 scale. After building mine from plans, I'm convinced it is a "kittable" airplane at least for the experienced builder. There were only a few areas where the engineering or construction was a bit more work than a simpler WWI kit:
- the fiberglass nose cap made from scratch
- engineering the connections at each end of the tail struts, plus getting the tail and tail strut alignment setup correctly. I made mine out of carbon fiber tubes which made engineering the connections a little more difficult. I had to make custom fittings that could be epoxied into the tubes & then used steel straps to bolt them to the air-frame on each end. Wood tail struts would be a lot easier to connect, but I wanted to minimize tail weight.
- integration of pulleys into the pull-pull systems. I think the pulley blocks one can get from a model sailboat supplier work well for a quarter scale DH2. Using these made life simple for me. My definition of "well" is high-reliability (at the expense of probably not looking exactly scale). This is what I used on mine.
Not that any of the above were impossible, just a bit more work & engineering than a simpler kit would require.
best of luck on your DH2!
Greg
Maybe, just maybe, it might be easier to get DH-2s in the air.
The DH-2 has always interested me. Now with my 1910 Curtiss Hudson Flier and AVRO Triplane projects (almost) behind me, I thought it would be great to do a next project that would have a broader appeal and maybe even kittable. I've started on the design and have even had some conversations with a kit company with the idea that they might carry this as a kit.
Here are some very preliminary CAD illustrations. The design has progressed from there and there is still lots more to do but I am feeling pretty good that a 1/4 scale kit can be designed for a manageable build without too many non-scale compromises. We'll see.Sorry for the intrusion. Great work R/C Art and congratulations on a magnificent project!
The DH-2 has always interested me. Now with my 1910 Curtiss Hudson Flier and AVRO Triplane projects (almost) behind me, I thought it would be great to do a next project that would have a broader appeal and maybe even kittable. I've started on the design and have even had some conversations with a kit company with the idea that they might carry this as a kit.
Here are some very preliminary CAD illustrations. The design has progressed from there and there is still lots more to do but I am feeling pretty good that a 1/4 scale kit can be designed for a manageable build without too many non-scale compromises. We'll see.Sorry for the intrusion. Great work R/C Art and congratulations on a magnificent project!
12-03-2016, 07:29 AM
#393
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All good points E_P. One of the ideal aspects of a kit would be that the wings don't need functional rigging. If the wings are kept in one piece, I thing that is doable. But that means that the only practical break down is to remove booms with the tail intact. Again, I think it is doable.
As for the booms, to keep the expense down and ease of construction up, either brass tubing or wood dowels can be used. Based on input from the kit company, I'm going with wood dowels, primarily for the low cost. Of course the builder can go with brass or carbon fiber if they are up to it.
I think I have a very good way to make the connections from the booms to the wings easy and reliable. The tail to the booms is more of a challenge, mostly with intent of keeping the build simple but reliable. Not done yet but I am making progress on that front.
One could put the elevator and rudder servos in the wings and run golden rod down the booms for control but that would certainly be a non-scale compromise that would be very inadvisable but it is an option. Pull-pull is definitely the way to go with this plane.
The pulleys are always a challenge. For my other projects, I never found a good source for off-the-shelf pulleys. I'd like to know what you have used. In the past, I bought plain pulleys from Advance Composite Products and made my own brackets. Since then, I turn my own pulleys so that the groove is deeper than the ACP ones. Less likely for the cable to jump the pulley.
As for the fuselage cone, it looks like a molded ABS one-piece is going to be the approach. The kit company I talked to seemed OK with that approach. Since I will have to make a core, fiberglass versions could also be made.
Thanks for the tips.
As for the booms, to keep the expense down and ease of construction up, either brass tubing or wood dowels can be used. Based on input from the kit company, I'm going with wood dowels, primarily for the low cost. Of course the builder can go with brass or carbon fiber if they are up to it.
I think I have a very good way to make the connections from the booms to the wings easy and reliable. The tail to the booms is more of a challenge, mostly with intent of keeping the build simple but reliable. Not done yet but I am making progress on that front.
One could put the elevator and rudder servos in the wings and run golden rod down the booms for control but that would certainly be a non-scale compromise that would be very inadvisable but it is an option. Pull-pull is definitely the way to go with this plane.
The pulleys are always a challenge. For my other projects, I never found a good source for off-the-shelf pulleys. I'd like to know what you have used. In the past, I bought plain pulleys from Advance Composite Products and made my own brackets. Since then, I turn my own pulleys so that the groove is deeper than the ACP ones. Less likely for the cable to jump the pulley.
As for the fuselage cone, it looks like a molded ABS one-piece is going to be the approach. The kit company I talked to seemed OK with that approach. Since I will have to make a core, fiberglass versions could also be made.
Thanks for the tips.
12-03-2016, 08:09 AM
#394
Hi Chevelle,
Yeah, I mentally wrestled with where to make the breakdown points in the architecture. Here's where I came out on it (always more than 1 way to skin a cat).... To make the tail booms removable, I was concerned about the removable connections that would be required in the rudder & elevator pull-pull systems (I thought to myself that's an additional failure mode in a critical system). So I elected to make that a permanent assembly (tail booms stay on the center sections & tail fins) and call that whole assembly the fuselage figuring there was less to go wrong.
This required the wings to be partially removable as outer panels (the wing center sections stay with the "fuselage"). I was more confident in my ability to build that type of connection because that's how my 1/3 scale Pup wing panels are connected & this works well.
This actually made the use of functional rigging a little easier; since the wing center sections stay with the fuselage assembly; I only had to install the functional rigging for the center section once & then it stays on all the time. It did require me to have functional rigging for the connecting the other panels to the wing center sections, but that's only 4 connection points for the whole thing. What about the X-bracing between the front & rear outer struts you may ask... I leave those cables attached to the outer panels, only the inter-plane struts come out when removing the outer panels. This speeds up field assembly.
Here are the pulleys I used:
http://www.halesmicro.com.au/
These pulleys were super simple to install, strong & reliable. With that design, I don't have to worry about an axle backing out or the pulley binding with the cable. They were easy to mount to an aluminum bracket in each location. I don't have the machining equipment to make my own pulleys so these were a good solution for me.
I think you're on the right track with the wood tail struts; if I had to do mine over, I'd probably go this way too. I put in fair amount of effort with the carbon fiber tubes for what was probably a small weight savings (plus gray paint doesn't stick to carbon tubes very well). With a gas engine on the back of the firewall, nose weight will be required but with this much wing area it can carry that with no problem.
I'm interested to see how you develop the removable tail boom structures and pull-pull connections. I'm sure there's a clever way to do this.
Greg
Yeah, I mentally wrestled with where to make the breakdown points in the architecture. Here's where I came out on it (always more than 1 way to skin a cat).... To make the tail booms removable, I was concerned about the removable connections that would be required in the rudder & elevator pull-pull systems (I thought to myself that's an additional failure mode in a critical system). So I elected to make that a permanent assembly (tail booms stay on the center sections & tail fins) and call that whole assembly the fuselage figuring there was less to go wrong.
This required the wings to be partially removable as outer panels (the wing center sections stay with the "fuselage"). I was more confident in my ability to build that type of connection because that's how my 1/3 scale Pup wing panels are connected & this works well.
This actually made the use of functional rigging a little easier; since the wing center sections stay with the fuselage assembly; I only had to install the functional rigging for the center section once & then it stays on all the time. It did require me to have functional rigging for the connecting the other panels to the wing center sections, but that's only 4 connection points for the whole thing. What about the X-bracing between the front & rear outer struts you may ask... I leave those cables attached to the outer panels, only the inter-plane struts come out when removing the outer panels. This speeds up field assembly.
Here are the pulleys I used:
http://www.halesmicro.com.au/
These pulleys were super simple to install, strong & reliable. With that design, I don't have to worry about an axle backing out or the pulley binding with the cable. They were easy to mount to an aluminum bracket in each location. I don't have the machining equipment to make my own pulleys so these were a good solution for me.
I think you're on the right track with the wood tail struts; if I had to do mine over, I'd probably go this way too. I put in fair amount of effort with the carbon fiber tubes for what was probably a small weight savings (plus gray paint doesn't stick to carbon tubes very well). With a gas engine on the back of the firewall, nose weight will be required but with this much wing area it can carry that with no problem.
I'm interested to see how you develop the removable tail boom structures and pull-pull connections. I'm sure there's a clever way to do this.
Greg
01-01-2019, 06:38 PM
#395
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Hi Greg,
I'm also scratch building a DH-2 from my own plans. I was wondering if you could post any detail pictures of your rudder and elevator pulley brackets, and where did you end up locating your batteries?
I'm also scratch building a DH-2 from my own plans. I was wondering if you could post any detail pictures of your rudder and elevator pulley brackets, and where did you end up locating your batteries?
01-04-2019, 09:58 AM
#396
Elevator pulley (double block)
Hi Ron,
Thanks for the question. I've attached a couple of photos showing the rudder & elevator pulley brackets. I made the brackets simply by bending strips of aluminum & then drilling holes to bolt the pulleys on. In the subsequent 4 flying seasons this has proven to be very secure. You will also notice I used model sailboat pulleys. These are very well engineered and I was willing to sacrifice a little bit of scale detail for the added reliability (or at least the peace of mind).
best regards,
Greg
Last edited by Eindecker_pilot; 01-04-2019 at 10:06 AM. Reason: trying to attach photos!
01-04-2019, 01:46 PM
#398
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Greg,
Thanks for the quick response. I created my DH-2 model in Solidworks, laid out the parts to laser cut in Autocad, and printed my build-to plans and started building.
This is a challenging build! I am currently wrestling with how to power, gas or electric. leaning toward electric for a variety of reasons - but have no experience with large model electrics.
I was glad to find your electric build and hope you don't mind a few questions in the future.
Thanks again,
Ron
Thanks for the quick response. I created my DH-2 model in Solidworks, laid out the parts to laser cut in Autocad, and printed my build-to plans and started building.
This is a challenging build! I am currently wrestling with how to power, gas or electric. leaning toward electric for a variety of reasons - but have no experience with large model electrics.
I was glad to find your electric build and hope you don't mind a few questions in the future.
Thanks again,
Ron
01-04-2019, 07:47 PM
#399
Hi Ron,
After trying every possible alternative, I eventually reverted mine to gas power.
I did initially have success with the electric power but I found myself wanting much more flight duration than lipos could provide at a reasonable weight. I could only get 6-8 minutes of flight using electric and that was with a lot of lipos onboard. If I recall correctly I was flying with 5,000mah of capacity (8S). The lipos were mounted just behind the nose cap on a wooden tray I made which fit under the machine gun, in front of the pilot bust in the cockpit. This did make swapping out the bricks easy.
My advice is to go with gas power unless you don’t mind landing every 6-8 mins. Lipos just don’t have sufficient energy per unit of mass to work well on such a large, high drag aircraft.
When spec’ing an electric propulsion system, you have a number of parameters you can play with (voltage, prop size, motor size, battery size). I used Motocalc simulation software and optimized the heck out of the system and could not get the 20 minutes of duration I wanted. I was encouraged because the predictions were coming in at about 17minutes of predicted cruising duration (after optimizing the system specs) so that seemed good and I went with it.
However in real life I only got about 8 mins max. The simulation under predicted how much drag this airframe has and therefore underpredicted my electrical current draw in flight.
Ultimately, there was no weight penalty going from electric to gas becuase I had to carry such massive lipo batteries. It also helped that I went with a lightweight gas engine (the OS GF40).
best regards,
Greg
After trying every possible alternative, I eventually reverted mine to gas power.
I did initially have success with the electric power but I found myself wanting much more flight duration than lipos could provide at a reasonable weight. I could only get 6-8 minutes of flight using electric and that was with a lot of lipos onboard. If I recall correctly I was flying with 5,000mah of capacity (8S). The lipos were mounted just behind the nose cap on a wooden tray I made which fit under the machine gun, in front of the pilot bust in the cockpit. This did make swapping out the bricks easy.
My advice is to go with gas power unless you don’t mind landing every 6-8 mins. Lipos just don’t have sufficient energy per unit of mass to work well on such a large, high drag aircraft.
When spec’ing an electric propulsion system, you have a number of parameters you can play with (voltage, prop size, motor size, battery size). I used Motocalc simulation software and optimized the heck out of the system and could not get the 20 minutes of duration I wanted. I was encouraged because the predictions were coming in at about 17minutes of predicted cruising duration (after optimizing the system specs) so that seemed good and I went with it.
However in real life I only got about 8 mins max. The simulation under predicted how much drag this airframe has and therefore underpredicted my electrical current draw in flight.
Ultimately, there was no weight penalty going from electric to gas becuase I had to carry such massive lipo batteries. It also helped that I went with a lightweight gas engine (the OS GF40).
best regards,
Greg
Last edited by Eindecker_pilot; 01-05-2019 at 05:42 AM. Reason: edited total mah capacity I was using.
01-05-2019, 04:55 AM
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Greg,
Wow, just the kind of useful info I was looking for! I have a Syssa 30cc gas engine that I had in a 1/4 scale Hanriot so I will try to use it.
any advice on fuel tank mounting or prop choice?
Thanks for your time,
Ron
Wow, just the kind of useful info I was looking for! I have a Syssa 30cc gas engine that I had in a 1/4 scale Hanriot so I will try to use it.
any advice on fuel tank mounting or prop choice?
Thanks for your time,
Ron