Comment by Paul Mather on June 25, 2011 at 7:50am

Trent, I like watching your videos. There are a few things to consider when building your next plane.

The plane you made is similar to the Ace Simple 400. With the diherdral it should be much easier to keep level...the Simple 400 would fly straight as an arrow but it doesn't auto-level in any way.

You'll notice how much shorter the nose section is vs your plane and that the wing chord is bigger giving it more lift. I also think you're way underpowered. What's your AUW? If you're in the 14oz range, then I would recommend a APC 9X6E prop and a 1300 to 1500kv motor. That should pull about 20-23A at WOT. You should be in the 60g range for motor weight. I would also strongly recommend a prop saver with o-ring instead of a collet directly on the motor shaft.

When testing CG it should be 1/3 back from the leading edge of the wing. I've had a few warplanes where the CG was right on the leading edge, but generally (and especially for your plane design) it should be 1/3 back.

I would also recommend only using CA glue with accelerator. Stop using hot glue. The hot glue is heavier melts too easily in your car and doesn't give you any better sticking power on the kind of foam you're using. Plus, you've got to have a car with an inverter to make a hot glue repair in the field. CA fits in your pocket and takes seconds to dry with a spray of accelerator.

Another thing I'm not sure about with your design. The "modular" aspect is not going to be helpful for this long range flight. As you can see from the crashes in this video, the nose and fuse modules are going to get destroyed together. Since you're making this out of 6-8mm foam, a hobby knife and some CA glue should make for a quick fix even without the modules. If this is going to be the platform for your disatnace flight you're going to need a LOT more payload room. You're going to need a Video TX, autopilot, GPS and camera plus probably a few sensors for current and airspeed. I'm thinking you're going to need to learn about hot wire foam cutting and plan to crash less (or bring a dozen fuselages with you on your drive).

Doing the math rather quickly, you're going to need to average 43MPH for 10 hours a day for 7 days in a row. That's 70 hours of flying!?!? Plus battery changes every 30 minutes let's say? This is going to be a VERY difficult task. You'll need a 2100 mah battery at least to get that 1/2 hour of flight (on a small plane) and a very thin airfoil to make the speed. It's going to have to be BIG to handle the winds you may encounter during rain storms and when flying across tha plains.

Moderator Comment by Gary Mortimer on June 25, 2011 at 8:22am

Never launch any model until you confirm for yourself that the control surfaces are moving in the correct direction!! Its your before take off check!

You might want to put your receiver behind your battery as well as thats is going to go straight through the receiver in a good nose hard arrival.

Looks like a pretty big battery maybe try something smaller and lighter until your flying well.

Keep going though its all looking good.

Comment by Paul Mather on June 25, 2011 at 8:31am

The more I think about this, the only way you're going to make this work is with about a 2 lb plane with a pretty good size wingspan (say 70"). I'm thinking carbon fiber for the wings and fiberglass for the fuse. It needs to be as aerodynamic as possible. The 2lb weight would give it enough ballast to handle some wind. One large drawback to moving the motor from the nose to the tail is you'll lose all slow speed control ability. There won't be any air forced over the control surfaces until the plane picks up speed....unlike when it's on the nose, as soon as you hit the throttle, you get wind over the controls. You're right that moving it to the back will protect the motor more on a crash, but without a prop saver, your prop is probably still toast.

So then there's the issue of the prop in the field of view of the camera. So you can either make a boom that sticks up over top of the prop to hold the camera or you can mount the camera under the plane pointed down a bit. Using the landing gear (maybe) to protect the camera.

Wow.... It's really going to be an engineering feat. Building a plane that's well suited for FPV, speed, distance, duration and is a UAV all in one.... I don't know if it can be done.

Moderator Comment by Graham Dyer on June 25, 2011 at 11:14am

I've learned the hard way too, so now I always do a "CATT" check - Controls (direction and free movement of all surfaces), Antenna (check it's extended), Transmitter (Voltage, trims, switches, dual-rates) and Timer (start it, if you have one), then throw...:)

 

As for CG there's lots of CG calculators on the 'net, I start at 25% of the root chord of a conventional wing and move back from there after the maiden. 30% is sometimes too far back for a maiden. Here's a link to my favorite calculator: http://www.pdqdesign.co.za/CG_Calc_wing_best.xls

 

Full marks though for experimentation and perseverance! Good luck and happy landings!

Comment by Hamish on June 25, 2011 at 11:32am

what are you trying to do ? find out how to make a plane by trial and error?

 

http://www.airfieldmodels.com/information_source/index.htm is pretty old but it has lots of info.

Everything at this mit course site is very interesting for basic aircraft design, especially this PDF

 

 

Comment by Trent at MyGeekShow on June 25, 2011 at 1:05pm

You guys are awesome... I read every comment very carefully and do my best to work in your recommendations the best I can. After I build the MTP II I'll report all it's stats (wing area, thrust, weight, etc.) to see if you guys see any blaring issues.

Hamish said it best: "what are you trying to do ? find out how to make a plane by trial and error?" actually I am : )

I have 4 other kit airplanes that I fly frequently, but in the end, none of them will be able to make the trip (my cross-USA trip) like I'd like them to. I've got to master how to conceptualize, build, and perfect a design. Unfortunately for me, I'll have a few bumps on the way.

Thank you all for your support!

Comment by John Hestness on June 25, 2011 at 2:19pm

My default glue is epoxy. It works on almost everything (except Multiplex airplanes I have heard) It is strong, and predictable.  I reccomend getting it at your local hobby store, the one time I ordered it on line, one of the caps was loose, and even though it was sealed in a plastic bag, the inside of the bag was such a mess that I threw away the whole bag. Epoxy also requires small mixing cups and popsicle sticks, make sure to mix it well.  I like the 15 to 30 minute variety, sometimes 5 minutes is not enough time to line things up.  For some reason I have had bad luck with CA.

Comment by Michal on June 25, 2011 at 4:47pm

Trent - I dont understand why you are publishing your efforts without digging theory first. It seems the only reason for this is to gain publicity. Without theory your attempts look indeed like trial and error. They will look like this till you will read more about the subject. Hamish gave you the links. Begin with pdf he mentioned.

The funny thing is that I posted you some advices on your YT channel and you deleted it. What was your point?

Comment by Trent at MyGeekShow on June 25, 2011 at 6:56pm

Michal: I see your concern about my approach in publishing my efforts, just know that I do it that way for a few reasons;

First, it's a show, "my geek show" and to that effect is designed to show my progress, however weak or strong it is, in the end I hope it is worth watching for those interested in getting in the hobby, learning more about it, or laughing at my ignorance but impressed by my desire to not give up and figure it out.

Second, I hope that people learn from my successes/failures and won't make the same mistakes I do. I learn a lot this way; watching what others do, and I wish they too would not only show what works, but what didn't.

Lastly, I think showing the mistakes I make sheds light on the amount of work and testing we all do to get that perfect airplane in the air, it's not easy, but it is possible and the joy we get from the journey makes it worth it.

 

About deleting your note, I have a very strict belief about not removing comments on any of my videos/blogs/etc. as I genuinely value all comments, even those that are negatively criticizing my efforts. To date, I have only removed one as it only contained vulgarities, and I know it wasn't from you. If your comment was removed, I assure you it wasn't by me.

Thank you for watching and pressing me to be better. Someday I hope you will watch an episode and say: "Alight Trent, good job, that was worth my five minutes"  : )  When that happens, let me know!

Moderator Comment by Brian on June 25, 2011 at 7:52pm

Trent: I find the MyGeekShow episodes entertaining and give a fresh perspective in "doing it your self". Keep up the great work. As far as doing checks before every flight... we'll you just have to, but even experienced fliers get distracted and forget sometimes. Recently, I drilled my setup two days in a row because I was very excited to test my AP but forgot to change the radio back to the model for the UAV. I can tell you that the Delta model the radio was set to and my plane are not compatible. So, I suffered a little wrinkle and loose tail but overall fared well, but I was lucky.

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