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Old Oct 07, 2014, 06:21 AM
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Thanks for that info. I guess the easiest way to say it is that the VTOL Trainer is more appealing to me for subjective reasons.
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Old Oct 07, 2014, 10:49 AM
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Thanks for that info. I guess the easiest way to say it is that the VTOL Trainer is more appealing to me for subjective reasons.
By all means, do what you like and have fun.

Be advised, fixed pitch tilt rotors are an inherent compromise between the low prop pitch that is needed to hover, and the higher prop pitch that would be best for forward flight. As a result, they tend to spin fast and require a higher throttle setting in forward flight. The resulting loss of efficiency limits flight times. SLT types don't have this limitation because they use separate props for lift and forward flight. One way or another, everything is a compromize though.
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Old Oct 08, 2014, 10:15 AM
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Interesting. I am not active in this VTOL portion of the forum, but I will assume some are looking at tackling this issue with variable pitch props. But for me, maybe another future project...

Thanks for the info. The local 3d print was cost prohibitive. At shapeways you can get the 4 motor mount systems for under $100 based on my mockup.. Not bad, if your time and access to tools prohibit making aluminum mounts. Of course someone would have to go through some revisions I'm sure to get them just right.
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Old Feb 03, 2015, 02:57 PM
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Any idea if the vtol trainer could carry 1lb of camera equipment if the right motors were used?
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Old Feb 03, 2015, 03:14 PM
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Any idea if the vtol trainer could carry 1lb of camera equipment if the right motors were used?
The short answer is Yes, it could. If I remember correctly it weighs about 3 pounds and the motors generate 5 lb of thrust at full throttle so it has enough thrust margin (barely).

When people ask this sort of question I always question the mission. The VTOL trainer was designed primarily to be a fun to fly sport model and a good entry point onto the world of VTOL aircraft. It might perform your mission, depending on what it is, but there might be better ways to do it. If you weigh it down with a pound of anything it might not be a fun to fly sport model anymore and it might not do what you need it to do either. Just because it can hover with that much weight doesn't mean that it will fly as far, as fast, or as long as you would like.
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Old Feb 03, 2015, 03:26 PM
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The short answer is Yes, it could. If I remember correctly it weighs about 3 pounds and the motors generate 5 lb of thrust at full throttle so it has enough thrust margin (barely).

When people ask this sort of question I always question the mission. The VTOL trainer was designed primarily to be a fun to fly sport model and a good entry point onto the world of VTOL aircraft. It might perform your mission, depending on what it is, but there might be better ways to do it. If you weigh it down with a pound of anything it might not be a fun to fly sport model anymore and it might not do what you need it to do either. Just because it can hover with that much weight doesn't mean that it will fly as far, as fast, or as long as you would like.
Thanks for the input, I just posted my own thread with some of the criteria of what I'd like. Hopefully I can get some input to help find something to best fit my requirements.
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Old Jan 18, 2016, 01:16 PM
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Has any one build this great design, of the VTOL Bixler trainer, in Europe yet. I tried to order the parts at http://www.mcmaster.com/, but they do not ship to europe any more. I do not seem to find where a can find the necessary parts for the motor gondles. Can any one give me some advice?
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Old Jan 18, 2016, 08:25 PM
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Has any one build this great design, of the VTOL Bixler trainer, in Europe yet. I tried to order the parts at http://www.mcmaster.com/, but they do not ship to europe any more. I do not seem to find where a can find the necessary parts for the motor gondles. Can any one give me some advice?
Post #211 shows one built in Denmark. There has got to be a source of general hardware in Europe but I don'[t know what it would be. Metric hardware is probably more popular there, but English sizes have got to be available as well.
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Old Jan 24, 2016, 10:39 AM
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I used hobbyking for parts

except tiltservos - the HK metalgear servos stripped the gears
now it uses HS-225
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Old Feb 17, 2016, 03:04 AM
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Dear Ran,

first of all thank you for the excellent work and description, building the VTOL trainer. Im from Germany and Im going to build up a VTOL trainer during the next weeks. I will nearly use the same material except of motors (NTM2826-1200) and ESCs (FVT LittleBee 20A) which I got very cheap at Hobbyking and Banggood. After reading the building instruction a few questions came up:
I did not find any information about the exact position of the motor pods on the wing. Its clear that the position is more or less defined by the cut profile of the wing, but the wing profile size does not change to much inside the ailerons, therefore this might not be very accurate.

Do you have an idea if the HS225MG are more at the limit for the motor tilt or more oversized? I have several servos here with similar torque available but unfortunately not the HS225MG. Unfortunately these servos have different sized and I would like to cut the right size of the servo opening.

By the way I had some trouble to find similar parts like the nylon bushings form MC Master (I did not want to order for such a small part from the US). In the meantime I have ordered washers for a TO220 heat sink for that purpose. I do not know if they will be fine for that application but I will let you know.

Since I have received already nearly all material I will start today to build up the motor tilts. My goal is, to have the maiden around Easter (this year ) I will certainly report my results here.

Best regards

Kai
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Old Feb 17, 2016, 04:01 AM
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Quote:
Originally Posted by frank100 View Post
Has any one build this great design, of the VTOL Bixler trainer, in Europe yet. I tried to order the parts at http://www.mcmaster.com/, but they do not ship to europe any more. I do not seem to find where a can find the necessary parts for the motor gondles. Can any one give me some advice?
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Old Feb 17, 2016, 05:16 AM
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I Didn't use any nylon bushings
just a regular M3 as axle, a pair of fibrewashers for support, and a locknut

and yes, i think HS-225 is quite alright, i haven't seen any indications of torq limits
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Old Feb 17, 2016, 06:57 AM
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Thanks for your hints.

Quote:
Originally Posted by polarit View Post
I Didn't use any nylon bushings
just a regular M3 as axle, a pair of fibrewashers for support, and a locknut

and yes, i think HS-225 is quite alright, i haven't seen any indications of torq limits
Do you think a S3150 would also be sufficient?
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Old Feb 17, 2016, 07:49 AM
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the HS-225 is 3,9 Kg/cm, the S3150 is 3,7 kg/cm (at 4.8 volt)

so yes, i think they will work
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Old Feb 17, 2016, 10:25 AM
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the HS-225 is 3,9 Kg/cm, the S3150 is 3,7 kg/cm (at 4.8 volt)

so yes, i think they will work
The recommended HS225MG is 3.88 Kg/cm compared to 3.7Kg/cm for the S3150 so the S3150 is slightly less but would probably work. The S3150 is also a slim servo intended for use as an aileron servo in a wing, and is $60 at Servo City. The HS225MG is only $26. I would normally run these servos at 6V for the higher torque values, but the S3150 does not seem to be rated for 6V. Taken altogether, it's a mis-application of the S3150 but it would probably work anyway.

Read post #210 for an explanation of why this torque is important and what can happen if it is insufficient. My initial design had HS85MG+ servos with 3.02 Kg/cm at 4.8V and they were inadequate in certain flight conditions. They caused several crashes before I got some high quality video and figured out what the problem was. On the other hand, they worked fine for a long time untill I happened to dive into an out bound transition. The already high forward airspeed when in hover mode at the beginning of the transition is what got me.

In other matters, I am not sure what impact the use of 2 blade props, instead of the 3 blade GWS props that I use, will have on this issue. Probably not much.
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