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JH Speed Deamon - a foamboard pylon racer
- Thread starter FAI-F1D
- Start date
I had no idea that existed. Yeah...gotta get one!
In other news, @Mid7night dusted me good with that 150+ mph run. I can't take that sitting down, so here's one of the uglier planes I've designed...there's 1500W in there, and only 20" span.
In other news, @Mid7night dusted me good with that 150+ mph run. I can't take that sitting down, so here's one of the uglier planes I've designed...there's 1500W in there, and only 20" span.
Glad I suggested it. Was painful watching you with the 100. You'll love it. You can lay a bead of glue all day long with the 200 and one squeeze of the trigger gets you a lot further.
Beauty is in the eye of the beholder and less is more. Unless it involves planes. More planes is better. For sure.
Can't wait for it's maiden and speed test. Love the competition you guys have going. Fun to watch. Visually and for simplicity, I like the idea of a single motor. Hope it kicks some butt!
Beauty is in the eye of the beholder and less is more. Unless it involves planes. More planes is better. For sure.
Can't wait for it's maiden and speed test. Love the competition you guys have going. Fun to watch. Visually and for simplicity, I like the idea of a single motor. Hope it kicks some butt!
Yeah, there ya go. Make sure you have someone else to throw that short winged bugger, preferably a javelin thrower. Remember slowing down will not be an option at all so landing will be a challenge (read that tip stalls). Oh and make sure you have a good bit of throw on that elevator both for yank and bank and for landing. But this is so cool! Best I ever did was years ago (1989) with a Quik-V (v1 modified) quickie 500 class with a Rossi .40, 165 on a police radar gun. Good luck and if you don't get the speed you want I have a few ideas for you 
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Best I ever did was years ago (1989) with a Quik-V (v1 modified) quickie 500 class with a Rossi .40, 165 on a police radar gun. Good luck and if you don't get the speed you want I have a few ideas for you .
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I did fly it last night on a 4s 2200...and crashed it on the third flight, managed to shim the motor the wrong direction. Patched up the fuse with 1/64" ply and went at it with a 5x5 prop since I killed my 5.25x6.25 (more are on the way).
Well I got it flying on the same battery and made several 85-95 mph passes at just under half throttle before bringing it in close at half throttle. When I turned to follow the plane an pull up to clear trees, I must have pulled the stick to the side because it rolled and hit the ground wing low at full speed, still at half throttle. The fuse ended up 20-30 from from the wing, battery and rx were both ejected.
Well time for a new airframe I guess. I'm going to try to add in a few inches of wingspan to address how ridiculously twitchy it is in roll (what actually caused the crash) and how hard it pulls to the left even with 2 degrees right thrust.
One piece of irony: it glides surprisingly well.
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I think you may be running into the limitations of a low AR wing. More wingspan, less chord.
You could reduce drag a bit by fairing the wing into the fuselage better.
And I wonder if your rear vent isn't causing turbulence as it's located far enough aft that the downwash from the wing may be hitting it unfavorably. I wonder about moving it into the wing itself so the low pressure helps scavenge air from the fuselage.
These are my random, uneducated thoughts that may do nothing to help, but there ya go.
You could reduce drag a bit by fairing the wing into the fuselage better.
And I wonder if your rear vent isn't causing turbulence as it's located far enough aft that the downwash from the wing may be hitting it unfavorably. I wonder about moving it into the wing itself so the low pressure helps scavenge air from the fuselage.
These are my random, uneducated thoughts that may do nothing to help, but there ya go.
Well that sucks..... but here are a couple thoughts.
#1 pinch in that fuselage at the rear behind the wing. A curved taper (exponential curve.)
#2 go with a v-tail set at 120 degrees, one servo with a Y shaped pushrod, two surfaces should be about 125% of the current Horizontals giving less frontal wetted area.
#3 iron your stab LE and TE to get better airflow.
#4 put a strip of foam inside the fuse at the corners and sand the corners round.
#5 droop the wingtips to keep airflow under and around the tips for stability.
#6 forget the vent act of the wing and just leave a small opening at the aft end of the fuselage.
All are just ideas and are only worth he paper the could be printed on.
Jeff
#1 pinch in that fuselage at the rear behind the wing. A curved taper (exponential curve.)
#2 go with a v-tail set at 120 degrees, one servo with a Y shaped pushrod, two surfaces should be about 125% of the current Horizontals giving less frontal wetted area.
#3 iron your stab LE and TE to get better airflow.
#4 put a strip of foam inside the fuse at the corners and sand the corners round.
#5 droop the wingtips to keep airflow under and around the tips for stability.
#6 forget the vent act of the wing and just leave a small opening at the aft end of the fuselage.
All are just ideas and are only worth he paper the could be printed on.
Jeff
I built a new one, with 4" extra span and side doublers to reinforce the fuselage in the wing mount area. Since I killed off my good props in crashes, I slapped a 5x5 bullnose on there. Well on 4s that gave a top speed of 116 mph before I ran out of battery. Launch is really smooth now. All of the stability problems are gone now. With an APC 5x5 the efficiency should improve and enable some more aggressive flying. Based on some tuned simulations on Ecalc, this should put me back on Ben's tail when I step it up to 6s.
It looks so pretty with a spinner. Man does it howl!
Oops. A new failure mode. Shed the wing on a full throttle pass. Radar said only 107, but I've seen 107...this had to have been 130 at least. Found the fuse 400' from where it shed the wing, and that occurred only 30' off the ground.
Unfortunately the fuse is too crumpled up front to be reused. Oh well... good excuse to widen the fuse 3/16" more for a better battery fit. I'll go to carbon wing pins from here on, 6 hold down bands, and two spars in the wing, which is also proving too floppy for the loads we're getting (have a look at the wingtips!).
Oops. A new failure mode. Shed the wing on a full throttle pass. Radar said only 107, but I've seen 107...this had to have been 130 at least. Found the fuse 400' from where it shed the wing, and that occurred only 30' off the ground.
Unfortunately the fuse is too crumpled up front to be reused. Oh well... good excuse to widen the fuse 3/16" more for a better battery fit. I'll go to carbon wing pins from here on, 6 hold down bands, and two spars in the wing, which is also proving too floppy for the loads we're getting (have a look at the wingtips!).
I built one of these during the week and holy crap, it flew amazing, did not even need trimming.
The only minor change I made was I widened the wings to the edge of the foamboard so they are about 2.5" wider and didn't use a power pod, since the motor screws have worked loose this was probably somewhat of an oversight, I also glued the wing on since I had no bands, another oversight.
But oh my, an absolute perfect design of a plane, nice one, most times I scratch build it goes horribly wrong, so I was ecstatic when this thing just lifted off out of my hand like a 3D Foamie being launched lol
The only minor change I made was I widened the wings to the edge of the foamboard so they are about 2.5" wider and didn't use a power pod, since the motor screws have worked loose this was probably somewhat of an oversight, I also glued the wing on since I had no bands, another oversight.
But oh my, an absolute perfect design of a plane, nice one, most times I scratch build it goes horribly wrong, so I was ecstatic when this thing just lifted off out of my hand like a 3D Foamie being launched lol