Mike Connor

My Feedback: (5)

All these maiden flights are getting me excited. Looking forward to some video.

mk1spitfire

exciting enough for you to make some more kits???????

skyflyer47

My Feedback: (2)

Hey Mike , and everybody else, I was able to get my electric motor fixed quicker than expected I hope for some good flights on sunday and a friend of does a real nice job on videos. Hoping it will all come together. Heres some pics of the inside and finished trim nothing special just for fun.

Mike Connor

My Feedback: (5)

I never saw an electric version of my design fly. Can't wait for the video.

skyflyer47

My Feedback: (2)

Just a question for all you aerodynamic gurus. Does a larger diameter prop cause more drag because of the disk area? Even if said prop provides more thrust.

evan-RCU

Yes.

Speedy-Gonzales

My Feedback: (202)

YES! Mega dittos.... evan-RCU [sm=thumbup.gif]

skyflyer47

My Feedback: (2)

ok thanks, but my electric set up seems happy with an 11 " prop 8 or 8.5 pitch. today I tried it with a 10-7 apc e prop. It didn't have enough thrust to take off out of the launchers hand and hit the nose hard then bounced on it again, the gusty wind was also a factor it caught under it and fliped it over. I was happy to see no damage except for a broken prop. Sorry Mike no good video yet, my video guy didn't show up. any way I did get a video of the crash with my camera not sure if I can load it because it's on a dvd from the camera.

skyflyer47

My Feedback: (2)

I'm sorry i lied, the guy I had running my video camera turned it off just before the crash then back on after. Oh well theres always tommorrow. It was the first time he ever tried to use it.

Mike Connor

My Feedback: (5)

Too small of a diameter prop can be as bad as too large of a diameter. The airframe and engine/motor needs to be considered. With a glow engine your delta would not need more then 9". Your setup must have a slow rpm and requires the thrust from a larger prop.

Troy-RCU

My Feedback: (1)

Well today I got some more good flights in! I also got some decent video of the Demon Tiger which should be uploaded by tomorrow night (sorry to tease). I am still working on getting the motor to run well. My first flight, which is in the video, was a bit too rich and didn't seem to get on the pipe. It tached at about 18,250 RPM with a 7.5X8 Q40 prop. My second flight, no vid, I was able to squeeze a bit more RPM out with 19,500 RPM & same prop. It still feels like the pipe isn't kicking in like it should but I will try a couple more things. I am running 15% and have cut another .75" off the header since the maiden flight(s). I wonder if I need to cut off more!?

Now with a few flights under my belt I am really starting to enjoy how well it flies. It is rock solid and grooves along. I think the winglets out on the end really keep things stable. They also work well with orientation when it gets far out. Launching is a no issue so far but not quite able to self launch yet. Everyone at my field loves it and is amazed I am firing up a glo plane and getting greasy. Although when the motor gives me starting fits I am quick to remind them why I haven't rushed back to glo in a while

cncswiss1

What RPM aare you getting? it sounds like the motor has to low of a KV for the number of cells and RPM goals you have. lower KV motors need more cells to spin fast with smaller props. what is your setup? (#cells , motor KV , and max amps?)

with 3 cells you are looking fior ~2000 kv minimum (aiming for 20k RPM no load speed) for good speed I'd be closer to 3000kv (30kRPM)
with 4 cells ~1500 Kv minimum (aiming for 20k RPM no load speed) I'd prefer 2000kv or more for 4s speed use.

a good quick and dirty formula is: no load rpm goal/(#cells * 3.5) = good starting KV
then use moto calc to determine the wattage required to spin the diameter prop you want that rpm and fine tune the setup.

skyflyer47

My Feedback: (2)

I am running an Axi 2826/08, the KV is 1130, It tacked out at 12,900 with a 11-8 apc, 13.200 with the 10-7. I am using a 3-cell battery 4000 mah.
according to my watt meter it draws about 60 amps with the 11-8, 630 watts. this motor only can handle 3 cells.
I think my crash was more due to gusty wind and poor throw than lack of thrust.
where can i get an out runner with the 2000 kv you speak of?

cncswiss1

Amperage and wattage cooks motors, not voltage. that motor can handle more cells, but you must use a smaller prop to do so.

try 6 cells and a 8-6 for starters. then ease up in pitch as the wattage allows. the hard part is getting 6 cells to not weigh a ton. a simple Y connector and using your existing 3 cell packs will work for testing, but may not be the lightest option.

part of your crash is the torque of that big lumber up front, and the gyroscop problems associated with it.


*edit for typo, it's 8" prop not 9" OOPS

skyflyer47

My Feedback: (2)

wow never considered that. theres no way to fit both my 4000 mah packs in there. what would happen with 2 1600 packs, besides a very short flight?
Mine was built to just barely fit one pack.

cncswiss1

as long as you have the "C" rating to cover the ampl you intend to pull you will be fine.. @60 amps you will need 40c packs!

I have been playing on moto calc a bit and it helps a lot
http://www.motocalc.com/

what speed control do you have? is it up to 6c? to get about the same wattage ~630 on 6s requires a 7" prop

but you could spin that 7.5 x 8 pylon prop mentioned above at 18K rpm on the ground, but throttle management will be absolutely necessary or you'll cook that motor.. allow for good cooling, and keep full power blasts short.

Eric Lis

A 1907/1y with a 7x7 prop will work with a 70amp speedcontroller on 5s. I have that setup in my outlaw. It will turn the prop around 23k...if that helps.

Mike Connor

My Feedback: (5)

We are waiting.

skyflyer47

My Feedback: (2)

Ok what brand is that and where did you get a 1907/1y? I am running a 70 amp speed control not sure if I said that? Hey Mike I might try for another flight today, no guarantees and no worries.

Troy-RCU

My Feedback: (1)

Video finally done. Enjoy!
http://www.youtube.com/watch?v=TPnXLDbEO9M

ps: any of the well tuned ears out there... this run was fairly rich (about 1200RPM low) but it still doesn't seem to want to jump on the pipe just yet. In my following run I leaned the needle & cranked out RPMs to 19,500 but it seems like there is more to be had. Could I see over 20K with this motor, 7.5X8 prop, and 15% nitro with a little more header trimming? I think I will try another 1/2" and re-tach.

Troy-RCU

My Feedback: (1)

Neu Motors makes the 1907/1Y. They are getting used a bit in ducted fans now. Try his motor calculator @ www.neumotors.com
or try here too: http://brantuas.com/ezcalc/dma1.asp

skyflyer47

My Feedback: (2)

Thanks I'll take a look at that. I figured out how to better launch my lickety split yesterday. I just had my helper hold it by both wingtips like I saw on some of you guys videos and back off on the throttle. 1/2 throttle is plenty to launch, it still torques left some but is managable. I also think right now it goes as fast as I can fly it with my current set up, after i get some stick time on it I'll think about increasing the speed. Sorry still no video

Mike Connor

My Feedback: (5)

Troy,
Thanks for the great video. I am impressed with your build and covering job. It was moving along quite well considering not having the engine dialed in yet. I was getting from 115 to 145 mph on Doppler. Would love to see another video when everything is just right.

mk1spitfire

great job on build now lets see you break 200mph, into wind of course!!!!

liquid_TR

Here is my demon; finally...

after a very looong break - I got the covering material, and finished the delta.
Now I know its not the best covering job - but hey, this is my first major covering job; done very quickly without planning.

The sheeting is 3mm balsa at the base with oracover over it. no glassing..
For the finishing touch I need a landing skid ideas.

anyone?