iron eagel

Based on Mike Connors PQ this was my first build of a speed plane, I have decided to named it the PQ Stingray Mk1. The airframe was set up using the stressed skin concept so the wing has no spars to keep the weight down. Still the finished RTF weight is a good eight ounces over the target which was two lbs max. I've included a few shots that show the airframe components being test fit and a few pictures during the build to give you an idea of how it was put together.
Specs 43 inch wingspan with a total of 516 sq inches of wing area.
Weight 2 lb - 8 oz with a 3200 mah 3 cell on board.
Motor HET 2W-23 2850 kv that is rated at 850 watts, with a Castle Creations ICE 100 ESC to put the juice into it, spinning an APC 6X5.5 prop.

Maiden flight was this afternoon and the launch was very interesting it really torqued hard left on launch. I am going to have to come up with a better method than just tossing it into the air...
Well at least it flew and is still in one piece, well more or less... The hatch cover came off but that's after it had been flow a bit, still got it on the back on the ground intact.
Lee the test pilot said "no trim needed right from the start" so I guess it's built straight and setup properly. Really did not get the chance to really see what it could do but it's pretty obvious that it is very quick.
I need to tone down the elevator a bit it's a bit twitchy in pitch, ailerons seem ok though so I think I'll use some expo on the elevator function. I got to come up with a better way to secure the hatch it came off so either the magnetic latch wasn't strong enough or the hinges just gave up I'm not sure which happened first. A launch dolly or a catapult would be helpful it really wants to torque hard left on launch.
I can't get the video off the video camera into my computer because there is no driver for my 7 year old Sony that works with windows 7 sorry about that. It wasn't all that good anyhow so you didn't miss much it would have been nice to see how fast we got it going though...

jeffk464

It looks really cool, does it have an airfoil?

iron eagel

The center section has the airfoil, the wings are essentially a flat plate variant that NASA experimented with for hypersonic flight that they designated the NADA.

combatpigg

My Feedback: (3)

Congratulations..!

Yes Siree, it really does look cool. Good thing the hatch didn't turn itself into a control surface.

It'll be interesting to see how fast it is. 2.5 pounds is still pretty light, so it ought to be a pretty sporty flyer.

iron eagel

Thanks,
I made sure to get a picture of the bottom color I thought you might like the color scheme.

Yea it was real lucky the hatch decided to leave cleanly. It ripped the hinges right out of the body when it came off, it just floated back down and landed on the runway about 20 feet from where we were standing. It departed on the second or third sprint attempt. When the throttle was pushed forward the plane literally jumped forward in the air, I can't wait to see what it it will do when given time to really spool up. I am pretty sure we got it past the 130 mark that was an issue with Mikes plane a couple of times but until I can get some video and have someone run Doppler on it it all just guesswork. Flying on the three cell it was quite spirited, it will be interesting to see what it will do with a 4 or 5 cell. With the three cell it was spinning up to at least 31k and we were just staying pretty level circles with it, with a four cell it could get up into the 51k rpm range with a 4X4 prop, a five cell may be problematic due to prop size but not beyond possibility. I really have to rig a launch dolly or catapult though like I said the launch was entertaining... It made a 90 degree left turn just after I let it go..
Hey do you have some pictures of that catapult you came up with that may be the way to launch this thing.

smoknrv4

My Feedback: (11)

Looks awesome, keep us posted on your progress. I love how thin and sleek it looks, so clean!

iron eagel

Thanks, it was based on Mikes idea, along with a lot of input from many guys who frequent this site in several forums, so lets say it was a combined effort...
Hopefully this Friday I will get into the air again and see if I can get some video of it in action. I have got to come up with a better way to get it airborne, the tossing a sheet of plywood concept is kinda hairy...

freakingfast

My Feedback: (3)

Yup, that can be a problem with a plane with power and a thin airfoil, the prop power torques it and the low air speed over thing wings gives little correction control. It got a bit exciting I take it? The good news is you saved it! You got the first launch (the rough one) out of the way, the rest should be easier. Next time try starting with the right wing low and the plane pitch up a bit. Do not start the flight in expo, you will need the controls "tight" and responsive at launch, once it starts haulin'a, then switch to expo. Expo at launch can lead to a vicious over correcting cycle that could end badly, fast servos or not.

Other hints: Avoid extra help in your ears, perhaps only a spotter. Next 5 or 6 launches should be into a light head wind, no wind is more difficult. Launch into wind at one o'clock,(wind is coming from 12'o'clock) that way it wont end up at nine o'clock and in trouble. Don't over think it, chill.
Once you get the hang of it it will be a piece of cake and a launch dolly or catapult is just more stuff to haul around.

Have fun!
Karl

vicman

My Feedback: (10)

Plane looks great!
There is no shame in a little tape to keep things sealed up. We use it all the time.
Karl said it right, launch with some angle and let it rotate level. My buddies Dust and my 1/2a Rivets go like that.

Congrats on the maiden.

iron eagel

Thanks guys...
I got to figure out a way to get some videos up.

iron eagel

Oh I meant to say this in reply, In the picture I am holding at the nose up angle at which we launched it, I did have the right wing at about 4 o'clock when I actually launched it. There was about a 5mph wind and I launched it just a little right of the actual direction the wind was blowing. I got to see if I can post the video of the launch it ended up going off about 90 degrees left to the direction I initially had launched it at. It may have been as simple as a stall and recovery. At my age I'm not into all the drama that this launch had, lol. After that takeoff I could have use some of Vicman's jar juice.

Edit to add:
Here is some data from the Castle Creations ESC data recorder of the maiden I was just able to download from the controller:
Peak RPM 25,585
Avg RPM 8,649
peak watts 935

vicman

My Feedback: (10)

daven

My Feedback: (1)

jar juice

combatpigg

My Feedback: (3)

Thoughts about the left turn / squirreliness on launch...

lateral balance checked..?

motor thrust..tiny bit of left is very bad, tiny bit of right is safe.

Top heavy designs [low wing and mid wing] with lots of upper side area are more tipsy at low speed

iron eagel

After looking at the video several times it looks as if it was a stall and recovery. After viewing the tape several times I saw that the nose dropped, it banked left and yawed left a bit as well as the prop finally got a good bite she picked up speed and he was able to fly it out. At least that's what it looked like, it happened so fast at the time the entire episode was over in a couple of seconds but really shocked me at the time. Once it got some speed she flew great no trim required the only real issue is the sensitivity to elevator inputs. And from what I gotten from the aerodynamics guys that is because of having the elevons rather than separate elevators and ailerons. Where the aileron function is barley adequate as it is I can't really limit the control throws mechanically so for the first time I am going to have to set up a plane with dual rates, expo and alike at least as far as the elevator goes. I am just looking at my Futaba radio to see how to do it as I have no clue how to program the darn thing. I have always been able to do the setup of my planes controls mechanically and never have used expo on a plane or radio in the years I have flown.

not that good but here is a video:
http://www.youtube.com/watch?v=73KvIXXCZac

iron eagel

Post flight inspection confirms that the motor shaft is bent and the prop adapter is now junk, if it wasn't from the beginning. The last run when the hatch came off the either the prop adapter or motor could not take the sudden application of throttle, which did in which is a matter for debate. Either way the maiden went well and I am now building the catapult launcher. As a note: We keep the plane out away from the runway deliberately to avoid injury if anything came apart. While there was no blazing speed in these runs it at least held together so the next time out we may try to see what it can really do.
I am going to have to drop the prop diameter a bit so it will spin up better, but am going to stay at the same pitch for now until we get a few good runs to see if the hatch and control issues have been resolved, maybe a couple of speed runs to see how it does. Then it should just be a matter of playing with prop pitch and diameter to get it dialed in to find the peak speed, if it really has any extreme possibilities. The one thing we did find out for sure is 130mph is no longer a barrier with this thin wing, I am pretty sure we went past that mark even if not by much.

Oh by the way CP the lateral balance was close, but I guess not close enough.

MJD

My Feedback: (1)

One of my Demons was notorious for launching exactly as you see in the video. It improved when I kicked the thrustline a bit to the right - it was close to zero but visibly a tiny hair left, and I mean

iron eagel

A few people have suggested a bit of right thrust would probably help...

I have been in the process of checking a few of the setup items,a couple of things I found were close but not dead on.
#1 Lateral balance was off to the left just a bit, the hold down straps and mount for the battery was the culprit here.
#2 Thrust line was was off to the left as well as much as a degree.
#3 The larger diameter prop while it gave it more thrust probably didn't help either.
Correcting these should help a bit, it beginning to look like a case of accumulation of errors made things worst then they should have been. Obviously what I though was close enough wasn't but at least the plane made it back to the ground so these flaws could be corrected. The flight was no easy task as the landing showed the plane's pitch control is way too sensitive to be flown without expo, only the skill of the pilot flying it keep it from going in from the start.

My launch left much to be desired, a bit too high of a angle, not enough bank to the right (I had some but a bit more would have helped) and I was just barely to the right of the wind I wanted to keep it away from the pits. I am glad I can skip the hot WD40 in the face. And I have to admit my days of tossing sheets of plywood has long since passed, I'd be lucky to get one onto a pile tossing it theses days. I couldn't get this delta further than 2-3 feet and it only weighs two and a half pounds.

Speaking of SD's I have one of the first Demon kits shipped, and had promised Mike that after I got this one in the air I would build it. He's waited a long time to see me put my electric version of a SD in the air now that I have this one built I have got to start on it.

evan-RCU

Awesome video, love the line... "you just got yourself a hotrod there Paul..."

Great landing too.

MJD

My Feedback: (1)

The throws on a Demon likely have little to do with your aircraft's needs, but for reference my low rate gives me maybe 1/8" elevator at full stick and is more than enough for high speed passes and circuits. Not enough for launches or landings of course.

iron eagel

Thanks!
I kinda liked it myself, it seems everybody thinks it's at least a hot rod, not too bad of a park flyer...
Yea he made a nice landing considering the control issues, it was very twitchy...

iron eagel

MJD,
Thanks that will give me a good place to start.
I had the throws set up at about 1/4 -5/16ths of an inch each elevon has a 1.5 inch cord and is 20 inches in length, not that far from a Demon. This thing does not have much as far as a roll rate but the elevator is way too effective.

Hey guys I know that the varying throttle and the lack of any close passes may make it difficult but can anybody get a Doppler on any part of the flight? Please?
Any speeds quoted are just estimates it would be nice to get an idea of what type of speed it did obtain, thus far it's just guesses.

iron eagel

Well finally got around to getting another flight in. Peak RPM was around 29600RPM using a 5X5.5 APC prop looks like I need to play with props to dial it in only drawing peak power around 650 watts I know it can take a lot more.

Here is the video of the flight the temp was about 60 degrees and I am at 20' ASL Elevation.
Could someone please run a Doppler I can not get it to work on my computer.

http://www.youtube.com/watch?v=LSvvgPOU8gI

iron eagel

Here is the recorded data from the second flight.

iron eagel

We used to be able to modify or edit the title of the post (if you were the original poster) but now I can't seem to be able to do it.
What's up with that?
I wanted to add that I have posted a new video, like I did when I added the first video...

I hope someone can Doppler this and tell me how fast it was going so I can decide on which way to go from here. Given the data I got from the flight I have what looks like two options.
First try a higher pitch prop like a 5.25X6.25, or the second leave the same prop and go up to a four cell instead of the 3 cell battery.
At least I did not bend the motor shaft with the prop adapter this time. I am leaning toward going with the higher cell count that should give me at least 3k more rpm over the 29K rpm with the 5X5.5 prop.