Official Roban 120mm A-10 Warthog V2 EDF Jet Thread

[crxmanpat]

I too would like to know if anything has been modified to make it more structurally sound. But if I got one, I'd be going twin 60 turbines for 30 lbs of thrust.

[PaulZ]

Now this is fantastic stuff! Finally a large EDF! I would not be too worried about the old version as now you have MRC behind it!

[OV10]

Alpha
Thank you very much for providing the authoritative response needed to bring clarity to a long standing concern regarding this model.
The factory response #3 and your multiple points of perspective regarding the wing structural integrity issues goes a long way to alleviating those concerns.
The only other concern I would like to have you comment on is the engine pods.
It is well known that the ChangeSun 120 EDF's were catastrophes waiting to happen and as such it was almost a requirement to use a more reputable power plant.
In order to do so it did require a major mod to the pods. Is it still designed for the Changesun EDF and if not, what is going to be recommended. What did you personally go with??
Best regards my friend

[T-CAT]

This thread took off over the weekend!

To those who asked some initial questions, here are answers directly from the factory:

1) All Roban 120mm A-10s in Motion RC's stock use a new steel landing gear pin. Initial batches sold by previous vendors had aluminum pins, and a handful were eventually shipped with steel, but during Motion RC's time with Roban we spec'd a stronger steel pin.

2) To better support the electric landing gear and aforementioned steel pin, the mounting areas within the main wing and fuse were reinforced.

3) Even more important than replacing aluminum gear pins, the main wing was significantly strengthened. Very initial batches sold by previous vendors were found to have had an issue caused by the manufacturing process. This issue could in some cases lead to delamination of the main wing's leading edge which could theoretically lead to a catastrophic failure. Retooling the production, assembly, and testing methods for the main wing has greatly reduced this risk.


Here are some of my personal observations of the composite Roban 120mm A-10:

1) Having developed the foam Freewing 80mm A-10, I can say unequivocally that it is best to think of Roban's A-10 as an entirely different bird in every way. The only similarity is that in the air a couple hundred feet away, their silhouettes will look somewhat alike. Treat everything else as different. Not necessarily Bad, but definitely Different.

2) I would not consider the Roban A-10 as full-speed-consecutive-bank-and-crank kind of rocketship, but rather a large composite scale bird.. It has plenty of rudder authority to be flown on its side like a pattern ship at reduced throttle to execute tight "scale" maneuvers, and a has a good roll rate and reasonable climb assuming you've managed its momentum before the climb. Recreating a full scale's range of maneuvers flown during a typical flight demonstration (YouTube) is entirely possible. The thing to remember is that it's a scale composite bird, so more gradual input is necessary to make it "look pretty" and also to avoid the "ragdoll" illusion. When flown scale, it really looks beautiful.

3) Depending on how it is outfitted by the builder, the model can end up being ~30lbs AUW. To a foamy driver, this will sound like a shocking number. Even to composite drivers, this will sound slightly higher than what might "seem" normal. But as a twin engine, twin rudder, ten servo beast, I would say that in the air it feels "planted" without being a complete slug. The advantages of its weight is that it penetrates through all wind conditions, and that it can build and maintain inertia much longer which potentially extends its flight duration assuming the pilot uses that inertia to reduce throttle. "Throttle Management" is key here, and candidly, flying an electric composite aircraft with this wing loading and planform will magnify a pilot's experience in Throttle Management, for better or worse. Pilots who know how to "ride" the wind will be able to stretch their flight times. Pilots burning watts at full throttle exiting a slow flap pass with a vertical climb attempt will be landing in 2.5 minutes.

4) The new main wing construction is stronger, based on wing flex texts (both static and dynamic). In any scale, an A-10's wing shape imparts stability at low speed and is in general quite easy to fly. The potential risk is that flight loads are exerted throughout the wing, which will always make an A-10 more susceptible to snapping a wing compared to, say, a Mirage. I believe that with the new wing and mindfulness of Point #2, the Roban A-10 shouldn't be at an excessive risk of failure. Composite drivers will already know this, but compared to foam aircraft, composite aircraft are much more rigid. Designing foam aircraft involves considering the material's properties for better and worse. In our Freewing 80mm A-10, we rely on certain degrees of flexibility in certain areas to give the model a softer ride, and depend on its rigidity in other areas to give it strength. With a composite plane, everything is rigid. This is a fact of composites. In foamies, a bit of wing flex is a good thing. In composites, it's most often not.

5) The fuselage joint didn't appear to have any problems, although it does leave a seam. If you don't think you'll need to separate the fuselage for transport, it's a joint that can be filled, although due to inherent flex I would use a flexible caulk first before a cosmetic layer.

6) The landing gear mounting areas appear strong considering the landing loads under normal landings. Hysol isn't being used at this price point, so if you're wary of any part of the airframe, strategic reinforcement can be done provided the AUW isn't increased too much. I am always wary to comment about landing gear durability because the factory "math" doesn't matter to pilots operating on airfields or at speeds/angles that the factory cannot account for. Suffice to say in my personal experience I haven't had any issues with the landing gear, but then again, I never had issues with a bouncing Freewing A-10, either, so your mileage may vary.

7) Speaking of airfields, you'll want a long area to slow down the model. I bring it in flat, full dirty, with power, using that power to manage descent. Too much power and you'll retain that heavy inertia all the way to the ground. Too little power and the wings will begin to wag.

8) The thrust line benefits from a deeper flap/elevator mix. We cheated on the Freewing A-10's thrust line to advantage its handling characteristics in the context of its wing loading.

9) It's not a CGRC A-10, and absolutely not a Mibo A-10. The key to happiness is managed expectations. The Roban A-10's cockpit looks really good. The office is nicely detailed. Other areas of its are softer in detail or proportion if you're really looking for it.

10) Use appropriate adhesives and fixatives depending on the materials being joined. The hinges make me thankful for Black Horse's pin-style nylon hinges.


I have other thoughts but will need to post them later. In the meantime, ask more questions and I'll answer what I have experience with. Needless to say, if anyone has any reservations about buying this bird, don't. If, by contrast, you've seen and heard enough to make you comfortable about taking on a big A-10 build, then this one is worth considering.


T-CAT @OV-10

Thank you for the detailed responses, Alpha.

[Aros]

Nice job Alpha on an informative post that should go a long way in helping folks make an informed purchasing decision.

[Alpha]

This thread took off over the weekend!

To those who asked some initial questions, here are answers directly from the factory:

1) All Roban 120mm A-10s in Motion RC's stock use a new steel landing gear pin. Initial batches sold by previous vendors had aluminum pins, and a handful were eventually shipped with steel, but during Motion RC's time with Roban we spec'd a stronger steel pin.

2) To better support the electric landing gear and aforementioned steel pin, the mounting areas within the main wing and fuse were reinforced.

3) Even more important than replacing aluminum gear pins, the main wing was significantly strengthened. Very initial batches sold by previous vendors were found to have had an issue caused by the manufacturing process. This issue could in some cases lead to delamination of the main wing's leading edge which could theoretically lead to a catastrophic failure. Retooling the production, assembly, and testing methods for the main wing has greatly reduced this risk.


Here are some of my personal observations of the composite Roban 120mm A-10:

1) Having developed the foam Freewing 80mm A-10, I can say unequivocally that it is best to think of Roban's A-10 as an entirely different bird in every way. The only similarity is that in the air a couple hundred feet away, their silhouettes will look somewhat alike. Treat everything else as different. Not necessarily Bad, but definitely Different.

2) I would not consider the Roban A-10 as full-speed-consecutive-bank-and-crank kind of rocketship, but rather a large composite scale bird.. It has plenty of rudder authority to be flown on its side like a pattern ship at reduced throttle to execute tight "scale" maneuvers, and a has a good roll rate and reasonable climb assuming you've managed its momentum before the climb. Recreating a full scale's range of maneuvers flown during a typical flight demonstration (YouTube) is entirely possible. The thing to remember is that it's a scale composite bird, so more gradual input is necessary to make it "look pretty" and also to avoid the "ragdoll" illusion. When flown scale, it really looks beautiful.

3) Depending on how it is outfitted by the builder, the model can end up being ~30lbs AUW. To a foamy driver, this will sound like a shocking number. Even to composite drivers, this will sound slightly higher than what might "seem" normal. But as a twin engine, twin rudder, ten servo beast, I would say that in the air it feels "planted" without being a complete slug. The advantages of its weight is that it penetrates through all wind conditions, and that it can build and maintain inertia much longer which potentially extends its flight duration assuming the pilot uses that inertia to reduce throttle. "Throttle Management" is key here, and candidly, flying an electric composite aircraft with this wing loading and planform will magnify a pilot's experience in Throttle Management, for better or worse. Pilots who know how to "ride" the wind will be able to stretch their flight times. Pilots burning watts at full throttle exiting a slow flap pass with a vertical climb attempt will be landing in 2.5 minutes.

4) The new main wing construction is stronger, based on wing flex texts (both static and dynamic). In any scale, an A-10's wing shape imparts stability at low speed and is in general quite easy to fly. The potential risk is that flight loads are exerted throughout the wing, which will always make an A-10 more susceptible to snapping a wing compared to, say, a Mirage. I believe that with the new wing and mindfulness of Point #2, the Roban A-10 shouldn't be at an excessive risk of failure. Composite drivers will already know this, but compared to foam aircraft, composite aircraft are much more rigid. Designing foam aircraft involves considering the material's properties for better and worse. In our Freewing 80mm A-10, we rely on certain degrees of flexibility in certain areas to give the model a softer ride, and depend on its rigidity in other areas to give it strength. With a composite plane, everything is rigid. This is a fact of composites. In foamies, a bit of wing flex is a good thing. In composites, it's most often not.

5) The fuselage joint didn't appear to have any problems, although it does leave a seam. If you don't think you'll need to separate the fuselage for transport, it's a joint that can be filled, although due to inherent flex I would use a flexible caulk first before a cosmetic layer.

6) The landing gear mounting areas appear strong considering the landing loads under normal landings. Hysol isn't being used at this price point, so if you're wary of any part of the airframe, strategic reinforcement can be done provided the AUW isn't increased too much. I am always wary to comment about landing gear durability because the factory "math" doesn't matter to pilots operating on airfields or at speeds/angles that the factory cannot account for. Suffice to say in my personal experience I haven't had any issues with the landing gear, but then again, I never had issues with a bouncing Freewing A-10, either, so your mileage may vary.

7) Speaking of airfields, you'll want a long area to slow down the model. I bring it in flat, full dirty, with power, using that power to manage descent. Too much power and you'll retain that heavy inertia all the way to the ground. Too little power and the wings will begin to wag.

8) The thrust line benefits from a deeper flap/elevator mix. We cheated on the Freewing A-10's thrust line to advantage its handling characteristics in the context of its wing loading.

9) It's not a CGRC A-10, and absolutely not a Mibo A-10. The key to happiness is managed expectations. The Roban A-10's cockpit looks really good. The office is nicely detailed. Other areas of its are softer in detail or proportion if you're really looking for it.

10) Use appropriate adhesives and fixatives depending on the materials being joined. The hinges make me thankful for Black Horse's pin-style nylon hinges.


I have other thoughts but will need to post them later. In the meantime, ask more questions and I'll answer what I have experience with. Needless to say, if anyone has any reservations about buying this bird, don't. If, by contrast, you've seen and heard enough to make you comfortable about taking on a big A-10 build, then this one is worth considering.


T-CAT @OV-10

[James]

So the fuselage is now epoxied. I used painters tape just aft of the seam to keep the epoxy off the fuselage (well, each for a dab I did elsewhere). I used 15 minute epoxy. I will include a pic next time with the interior where you can see I used some fiberglass cloth on the same for extra strength and keeping it lite.

I find that standing the fuse up like this to set and dry makes this the easiest method and allows you to set it straight. [when I walk away, I prop a stool next to it just in case.

[ in case you are wondering, I am also building the Roban B-25, again, so that is next to it. For comparison, the wing standing next to it, is the FW A-10]

Well, regardless of the hoopla here I am so excited to watch this build thread.

Pete, seems like your motivated to get this baby built. When you get her to the point we can take some static pictures, I'd love to swing by and check it out.

Again, thanks so much for posting pics and info on this one. Very much appreciated

[OV10]

OV-10,
I think you didn’t catch my response about #8/9. SO RCA is owned by Cliff and a friend of mine is a good friend of his. They worked on the demo A-10 and saw both the video and the wreckage. I wrote about their post ‘ ntsb’ results earlier in this thread series and told the story of how I folded a FW A-10 fuselage (James may have been there that day).

So I will do a good inspection and make comments of what I believe and what I do to counter any issue like that. We all have had lite-ply have an issue that if not inspected, will be a weak point. (Gee, had that on a Carl Goldberg Mirage 550 and fixed that prior to flying it). This is why this is a builder’s model, not some buy, screw and fly bird (sorry MRC, you are just selling us what we want and I have quite a few of them with repeats for bad hands or eyes or some other pilot ailment).

So, to answer 8/9 indications there was a problem that could have been caught, the airframe was over stressed multiple times in that flight (watch the video). That was from Cliff and Tom (my buddy). My observation is that he could have used some expo and flown it more scale like too or at least not bank and yank. Sorry if that is not what you were looking to hear, but I plan on calling this one straight and have to start here.

Hello Peter,
I did see your response the first time and it didn't answer any concerns the same as this response doesn't.
I am an experienced modeler and modder (see this build thread) as well as was a flight instructor and have owned the FW Warthog version and yanked n banked the dickens out of that with no issues so I am pretty absolute in saying that the pilot (you call Cliff) came no where's close to subjecting that airframe to overstress flight characteristics. That was my conclusion 2+ years ago when I saw the vid and if my recollection serves me correct is the same as what has been posted recently and has not been edited.
When did you buy this from RC Aerodydne ?? Back when they were clearing them out for the same price as the Mitchell you also have??
I am very familiar with this airframes history and that's why I need validation from the selling authority(Motion).
I don't intend to proceed to drop that amount of money if it still has the serious issues that will require major surgery to the wing and engine pods.
You may not mind being the lab rat here but I'm sure a lot others don't including myself.
I would also say that a composite fuse balsa build wing ARF is not a "builders" project.
I will follow what you do regarding inspection and comments and IF your documentation of the facts bear out that the risk is low and merits the purchase level asked then I may reconsider my very skeptical opinion of this.

[PeterGRC]

So the fuselage is now epoxied. I used painters tape just aft of the seam to keep the epoxy off the fuselage (well, each for a dab I did elsewhere). I used 15 minute epoxy. I will include a pic next time with the interior where you can see I used some fiberglass cloth on the same for extra strength and keeping it lite.

I find that standing the fuse up like this to set and dry makes this the easiest method and allows you to set it straight. [when I walk away, I prop a stool next to it just in case.

[ in case you are wondering, I am also building the Roban B-25, again, so that is next to it. For comparison, the wing standing next to it, is the FW A-10]

[PeterGRC]

And I don't think the response will be forthcoming anytime soon.
See my posts #8&9 . Not a peep from anyone with any official knowledge.
That folding wing video was indicative of the structural issues I referred to.
There is some bad mojo creeping all over this until someone from Motion provides some real answers.

OV-10,
I think you didn’t catch my response about #8/9. SO RCA is owned by Cliff and a friend of mine is a good friend of his. They worked on the demo A-10 and saw both the video and the wreckage. I wrote about their post ‘ ntsb’ results earlier in this thread series and told the story of how I folded a FW A-10 fuselage (James may have been there that day).

So I will do a good inspection and make comments of what I believe and what I do to counter any issue like that. We all have had lite-ply have an issue that if not inspected, will be a weak point. (Gee, had that on a Carl Goldberg Mirage 550 and fixed that prior to flying it). This is why this is a builder’s model, not some buy, screw and fly bird (sorry MRC, you are just selling us what we want and I have quite a few of them with repeats for bad hands or eyes or some other pilot ailment).

So, to answer 8/9 indications there was a problem that could have been caught, the airframe was over stressed multiple times in that flight (watch the video). That was from Cliff and Tom (my buddy). My observation is that he could have used some expo and flown it more scale like too or at least not bank and yank. Sorry if that is not what you were looking to hear, but I plan on calling this one straight and have to start here.

[PeterGRC]

As soon as I saw the post by MotionRC I was like I want one. I was looking at the Giant 165" Hangar 9 Cub until I saw this plane. I was in the first shipment of their other A-10. Of course, when looking for videos the video you posted comes up. If they haven't beefed up the spar then I will have to wait. Talking about close to 2500 - 3000 grand after all said and done. Not to lose it due to wings folding.

PLEASE TELL US THEY HAVE FIXED THIS ISSUE?

Whoa, can’t compete with a user name like that. I will be looking hard at that. If it looks fishy, I will reinforce.

[PeterGRC]

Thanks so much for getting on here Peter! I can't wait for further updates to your build and to eventually see this bird in the air

Thanks James. Hope we all can have a good discussion and if I get stuck, someone here has a suggestion.

[PeterGRC]

Hi Pete,
After reading the construction manual, I would whole heartedly agree with you that this is a "builders model" because of all the obvious upgrades it will require. Can't speak for the gear as you can and wouldn't try.
All I'm sayiing is that it seems that the average Motion RC buyer (and I am a huge fan) thinks they are builders when the put a wonderfully thoughtful Motion EDF together with 12 screws.
This is NOT that kind of aircraft.
Just think that before guys get attracted to some "cockpit lighting" they should think twice....especially for this amount of money....
Best of luck with your build, sounds like you know what you're in for and probably will come out the other end with a great flyiing airplane.
And BTW, I did start building way before there was such a thing as an ARF.
If more guys had more of a builders' skillset, they would have no problem in keeping their ARFs in great flyiing shape versus giving up on them to the trash can.
Stay Healthy

Tom,
You are so right, this kind of project is not a couple screws, Rx and battery and off the wild blue yonder or wild green grass with a rinse and repeat approach.

The cockpit lighting is a nice touch, but just a touch. I did some weather of my FW A-10 and enjoyed the look. Also added some 3D printed parts. Whoa, that was nicer. SO back with the disease of when is enough enough. My decision was to do the base Roban and add some neat things (brakes being one) and changing out the EDFs (personal preference and cost and at this size, cost does add up). [BTW, I picked JP Hobby fans and I will probably hear about it but like the sound and power for the cost - still ran $480 per fan).

So for those who haven’t tried it and willing to put in the time, learn some different techniques and spend some hard earned cash (I negotiated with the wife about a plane fund), it will be one of a kind or only a few at the field. Flying or static, it will draw a crowd. I took it to the field just in the box and had over a dozen guys swarming. And for those who haven’t had this type of challenge, well you will see what did and did not work and ask questions before you commit.

[OV10]

As soon as I saw the post by MotionRC I was like I want one. I was looking at the Giant 165" Hangar 9 Cub until I saw this plane. I was in the first shipment of their other A-10. Of course, when looking for videos the video you posted comes up. If they haven't beefed up the spar then I will have to wait. Talking about close to 2500 - 3000 grand after all said and done. Not to lose it due to wings folding.

PLEASE TELL US THEY HAVE FIXED THIS ISSUE?

And I don't think the response will be forthcoming anytime soon.
See my posts #8&9 . Not a peep from anyone with any official knowledge.
That folding wing video was indicative of the structural issues I referred to.
There is some bad mojo creeping all over this until someone from Motion provides some real answers.

[DrDeath]

https://www.youtube.com/watch?v=wR9VfuAWUgo Oh God. This aircraft is on my blacklist....

As soon as I saw the post by MotionRC I was like I want one. I was looking at the Giant 165" Hangar 9 Cub until I saw this plane. I was in the first shipment of their other A-10. Of course, when looking for videos the video you posted comes up. If they haven't beefed up the spar then I will have to wait. Talking about close to 2500 - 3000 grand after all said and done. Not to lose it due to wings folding.

PLEASE TELL US THEY HAVE FIXED THIS ISSUE?

[James]

All, I believe this is the same version as previously sold by RC Aerodyne. I built the B-25 previously and am Re-building it again (lost Rx power during end of maiden, ouch).

Now I also have this A-10 with the v2, reinforced, landing gear, so thought I would start the build and do a build thread here in stead of on RCGroups. James B has encouraged me to do so and to do it near stock so will start with posting a couple of pictures from the unboxing. Look forward to any suggestions and will do my best to capture a good part of the build.

Since it has some similarities to the B-25 from Roban, I hope to share some of the techniques I learned there.

Thanks so much for getting on here Peter! I can't wait for further updates to your build and to eventually see this bird in the air

[Tom Lasko]

Hi Pete,
After reading the construction manual, I would whole heartedly agree with you that this is a "builders model" because of all the obvious upgrades it will require. Can't speak for the gear as you can and wouldn't try.
All I'm sayiing is that it seems that the average Motion RC buyer (and I am a huge fan) thinks they are builders when the put a wonderfully thoughtful Motion EDF together with 12 screws.
This is NOT that kind of aircraft.
Just think that before guys get attracted to some "cockpit lighting" they should think twice....especially for this amount of money....
Best of luck with your build, sounds like you know what you're in for and probably will come out the other end with a great flyiing airplane.
And BTW, I did start building way before there was such a thing as an ARF.
If more guys had more of a builders' skillset, they would have no problem in keeping their ARFs in great flyiing shape versus giving up on them to the trash can.
Stay Healthy

[PeterGRC]

PeterGRC Welcome to Hobby Squawk and thank you so much for sharing your knowledge and build with us! I look forward to both!

Thanks Aeros. I think you and I exchanged notes on a VQ P-38 in another forum. Looking forward to it.

[PeterGRC]

Tom, much more complex than the foamies. I love foamies for quick assembly and just flying fun. Can’t be beat a lot of times. With you on that.

I built my first planes back in 1988/89. Learned by just following the instructions, blue prints and ‘figuring’ it out. Lot to be said for using the internet now and you tube.

Yes this model will take some time. Based on my B-25 build, which took a year, but that included learning to airbrush (see attached), well worth the effort. BTW, most construction techniques for building balsa are old school, so not sure where you come from. The skin is of course not what was done in the tissue paper and dope days (tried that as a kid, I sucked at it). Also, my largest problems for the B-25 was working with a buddy across the US to 3D print bombs and custom make the first tri-level bomb rack for 10 bombs to pickle away. What did we as a group learn? The nose gear was not up to it for grass fields.

That is why the v2 gear is shipped now (I got both the v1 and v2 gear with mine). Better. Not sure yet of best but finding an alternative is really hard.

SO this is more of a builder’s aircraft and understand if you are not up to it. Keep assembling and flying (I will too) as that is a blast. But I have re-learned the fun in building and solving challenges. Really lets me solve work problems while thinking on something else. What I call relaxing.

[Tom Lasko]

A lot of $ for an foamie that has structural problems, CA hinges, Aluminum wing tubes, No engines or ESC's, ect.......Read the completion manual.....Old Construction techniques all the way....about 10 years old in my opinion....Wouldn't touch this one with a 10' pole....
Sorry ....have "Build" not "Assembled" a ton of RC airplanes over 40 years and I call em as I see em.