Extreme speed NOT-prop plane
10-26-2015, 09:19 AM
#52
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Finally! A bright blue afternoon, and three guys for ground crew. Here is the staging area outside our side door..
Warm up plane - Demon, Evo .60NX/Jett muffler, 9-10.That's my original SD prototype, still going, third engine,
2pm.. gone flyin'
Warm up plane - Demon, Evo .60NX/Jett muffler, 9-10.That's my original SD prototype, still going, third engine,
2pm.. gone flyin'
10-26-2015, 05:12 PM
#57
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Darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit darnit
Everything went well today.. except, we did not realize the temps were low enough to kill the latex bungee. The viscoelastic damping was so bad, that with 120lb of tension in the thing, when the release was pulled, it just slid forward at about 5 mph.. funny as hell but we could not launch. All systems checked out up until that point, so onwards and upwards. Don't have an answer that doesn't involve about $300 more bungee cord yet..
Everything went well today.. except, we did not realize the temps were low enough to kill the latex bungee. The viscoelastic damping was so bad, that with 120lb of tension in the thing, when the release was pulled, it just slid forward at about 5 mph.. funny as hell but we could not launch. All systems checked out up until that point, so onwards and upwards. Don't have an answer that doesn't involve about $300 more bungee cord yet..
10-26-2015, 05:51 PM
#58
At the EDF forums it sounds like 5Gs is what they shoot for.
I can see now why a winch system would be popular.
At any rate, with a winch I imagine a short length of elastic in the line is needed to absorb shock.
The other idea is a launch pad on a car roof with a RC release.
What could go wrong...?
I can see now why a winch system would be popular.
At any rate, with a winch I imagine a short length of elastic in the line is needed to absorb shock.
The other idea is a launch pad on a car roof with a RC release.
What could go wrong...?
10-26-2015, 06:26 PM
#59
How many strands are you working with and at what length. I use to glider fly with latex tubing 1 strand per every 2lbs was the max rule of thumb but thats a glider. I would use 40ft latex plus another 100ft in string.
Perhaps 1 strand per every pound for the jet.
25 Feet 3/8" ID x 1/8" W x 5/8" OD Black Latex Rubber Tubing Surgical
49.95. 2 runs of this warmed up in the sun should do it with some 60ft of strong cord and a 2ft steel auger stake.
Perhaps 1 strand per every pound for the jet.
25 Feet 3/8" ID x 1/8" W x 5/8" OD Black Latex Rubber Tubing Surgical
49.95. 2 runs of this warmed up in the sun should do it with some 60ft of strong cord and a 2ft steel auger stake.
10-26-2015, 07:29 PM
#60
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3/4" OD x 1/2" ID natural latex, two strands of 18' each, plus mebbe 25' of leader. Each strand 50lb at 300% (4x) and 60lb (5x). We were at 400%, a bit over that second try.
Problem was the temperature and the viscoelastic behavior of the tubing. Since I only dabble in lekkies, I haven't been through the learning curve on bungees.. apparently many have been foiled by this in the past. All the tension was there, but the tubing was simply slowed down to a crawl - stuck in first gear. The thrust to weight at GTOW is only maybe 1.10 - 1.15, so all it did was a slow graceful toboggan slide on the grass at 135db. Quite comical actually. We got the starting drill down!
Problem was the temperature and the viscoelastic behavior of the tubing. Since I only dabble in lekkies, I haven't been through the learning curve on bungees.. apparently many have been foiled by this in the past. All the tension was there, but the tubing was simply slowed down to a crawl - stuck in first gear. The thrust to weight at GTOW is only maybe 1.10 - 1.15, so all it did was a slow graceful toboggan slide on the grass at 135db. Quite comical actually. We got the starting drill down!
10-26-2015, 08:18 PM
#61
Well that's nice that it sledded in gracefully. No torque roll to complicate things.
If you could immerse the tubing in an Igloo cooler full of hot water while the engine is getting fired and at the very last minute attach it to the plane, that might work.
If you could immerse the tubing in an Igloo cooler full of hot water while the engine is getting fired and at the very last minute attach it to the plane, that might work.
10-27-2015, 04:42 AM
#62
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Yeah, but the 120lb pull makes it a bit of a challenge to do anything quickly. By the time you lay it out and stretch it, then start the engine, I think it would be plenty cool again. I thought of two helpers, each poised with a bucket of hot water, quickly walking down the bungee as soon as the engine starts.
Actually the latest hair brained idea was to put a launcher out in front of the car, cantilevered off the roof racks. Start the PJ, disconnect and floor it.. release at 50.
Or fly in warm weather. But, we're thinking, we're thinking...
Actually the latest hair brained idea was to put a launcher out in front of the car, cantilevered off the roof racks. Start the PJ, disconnect and floor it.. release at 50.
Or fly in warm weather. But, we're thinking, we're thinking...
10-27-2015, 06:04 AM
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Find me a long enough cylinder, we'll talk!
Not sure how many gees I can inflict on this thing.. but 10 or 15 might be okay.
Of course I could do it with ramp and a rocket motor, but, at $30 a flight it gets silly.
Not sure how many gees I can inflict on this thing.. but 10 or 15 might be okay.
Of course I could do it with ramp and a rocket motor, but, at $30 a flight it gets silly.
10-27-2015, 11:53 AM
#65
Yea abrupt G forces will be of some concern no doubt.
Latex tube from 1/2" to 3/4" should overcome cold weather effect to a reasonable
degree due the dia. of the tube and thicker wall.
Another option would be a 1/2in dia steel springs joined together to make about 10ft
worth staked with cord going to the plane.
Door springs, here is one as an example they are cheap $6.80 local hardware store.
2ft sections. Others have used these with success. Or could just hire a 7ft guy to
hand launch it for ya
Latex tube from 1/2" to 3/4" should overcome cold weather effect to a reasonable
degree due the dia. of the tube and thicker wall.
Another option would be a 1/2in dia steel springs joined together to make about 10ft
worth staked with cord going to the plane.
Door springs, here is one as an example they are cheap $6.80 local hardware store.
2ft sections. Others have used these with success. Or could just hire a 7ft guy to
hand launch it for ya
10-27-2015, 12:10 PM
#66
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The tube diameter didn't seem to help, there is plenty of time for cold soak. It behaved exactly like the latex tube I was using to launch my Funjet when I tried it in cold weather. That was my only other bungee launch airplane.
10-27-2015, 12:37 PM
#68
Depending on what you find at the store if in 2ft sections about 10ft would be a good start, cold weather shouldn't effect it much.
With springs of various quality the good ones will snap back and hold there coil well.
With springs of various quality the good ones will snap back and hold there coil well.
10-27-2015, 06:44 PM
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I legitimized this thread for the XS prop plane forum, by entertaining the ground crew with a flight of the Demon/.60 NX. It hauls pretty well, indeed, but it's faster on the SJ .50 and West .50. Launches well on the NX with the 9-10, plenty of pull. I did a slow low pass, then throttled up, pulled vertical, and rolled it nearly OOS on high rate - then throttled back and let it fall back and roll down again, Plenty of oohs and ahhs. Not in those words form that crowd mind you.
10-28-2015, 05:13 AM
#70
I found this review just now. I've read many customer engine
reviews, but I think this one is in the top 3.....
If this isn't the cheapest 200 mph setup...then what is...?
Quality
Fun
Value
Raistlin
Location: Texas
I would recommend this to a friend!
PostedSeptember 25, 2012
Ok guys I am gonn do my best to destroy this little moter so here goes.I am putting this moter on a q500 viper arc . I started by running 20 oz of fuel through it for break in. The needles were a bit sensitive but that is common with your big displacement small case moters. My dub jet 60 is very similar on the needle.
Stock set up at the end of the short break in. 10-6 prop 17100. ( not bad at all with stock muff and 10%)
Ok now the fun starts
I raised the exhaust port timming to 191 degrees.
I bored the crank out 60 thousand (allows more fuel to pass)
I opened up the boost/transition ports up drastically
Removed the carb and spun a Venturi on the lathe and made a spray bar for it.
Drilled/tapped the case for crank case pressure and attached the vent tube to the tank
Attached a remote needle valve
I had several tuned pipes but settled on a Mac's 60 size tuned pipe.
I just did not trust the sport 10-6 prop so I went to a 9-9pylon prop that I never thought I would find a moter to turn.
To start it I closed the needle and hit it with the starter while it spins start opening the needle. As soon as you get fuel into the Venturi hit it with the glow lighter. I was surprised how easy it lit usually a moter with this aggressive timming takes 30-40 seconds to light but the ego lit right up Once I got it holding rpm (surging stops) I left the moter about 3 clicks rich and let it warm up I started to lean it out. The little sucker just kept going and going. Just when u would think it was wound out it would just wind up more and more.
So I brought the tac up to it and wow 21600 with 10% and the stock plug on a 9-9 prop WOW. But of course we are not done.
Next I machined the head down a conservative 20 housand To bring the compression up I also switched to a really hot plug and decided to leave the glow lighter on it while testing. This insures that the plug will stay hot and we won't hydro lock the moter.
Fired the moter up again this time using 50 % nitro
While the moter was running rich I fed a compound solution that I came up with which is caster oil, glow fuel and 1000 grit compound into the Venturi . This is a trick I learned when I raced pylon The grit hones the bearings and cylinder just a bit and usually get. U 300-400 rpm. Not advisable if u want this moter for the long term lol
Ok results After I found the compression to nitro ratio the moter liked, and a few drops of the compound to free her up I pulled 23100 on th 9-9 prop WOW this thing is a monster. Time will tell on the duribility but after disassembly there was no signes of abnormal wear.
I have done this exact same hop up on many many moters one of which was the Eco 46, to compare the 46 and 60 is like apples to oranges . The 46 after all the mods will turn an 8-8 at 22-23k where the 60 is knocking down 23k with the 9-9.
This is a great q500 moter with a little modification if you don't have a lathe you can still do most of the mods and have a 46 sized moter that will turn a 9-9 at 21-22k.
Great moter and after 11 test runs still scaring the you know what out of me when adjusting the needle lol
The only reason I gave it a three on the build quality was the castings were not cleaned up on the inside of the case as much as I would have liked and the bearings are not a name brand German type but hey for under 150$ who.can gripe.
Last edited by combatpigg; 10-28-2015 at 05:22 AM.
10-28-2015, 06:37 PM
#73
The Fora doesn't even open up the crank bore all the way down. They just make an oval 90 degrees from the crankpin axis. Maybe a 20 degree flare. The turbo cuts are common on the cars, but the Fora almost is the same as opening the bore, and it can be done with a dremel probably.
10-29-2015, 07:25 PM
#74
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Been working on this XS not-really-prop plane design over the last few days. Think I have a real simple positive feed fuel system worked out to run stock engine on gas.. testing and fiddling at the moment.
Almost ready to cut parts. Same Demon wing with different tips and spar arrangement.
Almost ready to cut parts. Same Demon wing with different tips and spar arrangement.
