JET-POWERED - Maverick Blackout V2
Discussion
Well - it's taken me the whole duration of owning a Maverick Blackout V2, doing the standard servo upgrades, upgrading the engine to a Zenoah G290 4-bolt, to this latest source of propulsion - to figure out how to upload images on a forum! Although, I think they've only just recently made it a heck of a lot simpler!
So what you now see is the Maverick with the 2-stroke engine decommissioned - with the source of propulsion now a Wren iKero100 jet turbine! I've been smiling from ear-to-ear for days!
It puts out 10kg of thrust, idles at 45,000RPM, and is on full-power at 160,000RPM. And the sound is in-fecking-credible.
I haven't actually had a chance to test it for speed - and it may require a shift in perspective over the vehicle - so far a powerful mud-plugger suited only to good grass for traction. Now it's probably more in its element on tarmac and slicks of some sort. However, I like that it's still a Maverick Blackout V2, which incidentally I have loved all the duration of ownership - it's such a fantastic platform, that it gave me the confidence to try this.
This is the sort of engine which can propel a person on a bicycle to 30mph+
I will make the wiring neater, but it's still in test phases! If anyone's interested in the ins and out, just ask here.
I've left the original engine and even petrol tank in, to add weight to aid traction for the steered wheels, and to aid general stability, and really the extra inertia at start-off is helpful to keep it behaving.
Start-up is no longer an affair with propane bottles, a separate source of blown air, etc - it's completely, 100% self-contained - you can literally walk up to the vehicle - turn on receiver, turn on transmitter, and start - it does all of the rest until idling and ready for transmitter control.
And guess what - it just runs on standard paraffin!! Plus a dash of two-stroke.
In garage testing, I had the two front wheels chocked each by a six-pack of 1.5litre Evian, longways, so hardest to push - this was designed to prevent any forward movement during testing - but it shoved these properly when at full-throttle!
I got the engine directly from Wren Turbines - with them being UK-based, it's a no-brainer, as good as Jetcats also are. Wren literally hand-build every engine.
Below: An update since first pics - revised fuelling solution (story further on in thread)
Latest, as at 11 July:
VIDEO!!! But be warned - it is quick, dirty, and shaky! Better coming soon, esp of actual driving (piloting!). From about 2mins10secs it's shut down and in cooling-down mode - fully automated, might be boring to watch for some, but coming to a standstill is part of the show! Also - because of the sound issue mentioned at the other end of this thread (page 3), this video is only of start-up and idle (50,000RPM).
http://youtu.be/W4whKFUgc_0
So what you now see is the Maverick with the 2-stroke engine decommissioned - with the source of propulsion now a Wren iKero100 jet turbine! I've been smiling from ear-to-ear for days!
It puts out 10kg of thrust, idles at 45,000RPM, and is on full-power at 160,000RPM. And the sound is in-fecking-credible.
I haven't actually had a chance to test it for speed - and it may require a shift in perspective over the vehicle - so far a powerful mud-plugger suited only to good grass for traction. Now it's probably more in its element on tarmac and slicks of some sort. However, I like that it's still a Maverick Blackout V2, which incidentally I have loved all the duration of ownership - it's such a fantastic platform, that it gave me the confidence to try this.
This is the sort of engine which can propel a person on a bicycle to 30mph+
I will make the wiring neater, but it's still in test phases! If anyone's interested in the ins and out, just ask here.
I've left the original engine and even petrol tank in, to add weight to aid traction for the steered wheels, and to aid general stability, and really the extra inertia at start-off is helpful to keep it behaving.
Start-up is no longer an affair with propane bottles, a separate source of blown air, etc - it's completely, 100% self-contained - you can literally walk up to the vehicle - turn on receiver, turn on transmitter, and start - it does all of the rest until idling and ready for transmitter control.
And guess what - it just runs on standard paraffin!! Plus a dash of two-stroke.
In garage testing, I had the two front wheels chocked each by a six-pack of 1.5litre Evian, longways, so hardest to push - this was designed to prevent any forward movement during testing - but it shoved these properly when at full-throttle!
I got the engine directly from Wren Turbines - with them being UK-based, it's a no-brainer, as good as Jetcats also are. Wren literally hand-build every engine.
Below: An update since first pics - revised fuelling solution (story further on in thread)
Latest, as at 11 July:
VIDEO!!! But be warned - it is quick, dirty, and shaky! Better coming soon, esp of actual driving (piloting!). From about 2mins10secs it's shut down and in cooling-down mode - fully automated, might be boring to watch for some, but coming to a standstill is part of the show! Also - because of the sound issue mentioned at the other end of this thread (page 3), this video is only of start-up and idle (50,000RPM).
http://youtu.be/W4whKFUgc_0
Edited by Arif110 on Thursday 31st July 23:28
Ha ha - indeed! I've yet actually to even run it on ground of any sort. It's said that an object of given weight will 'use up' 5% of that weight, of the thrust of the engine used, just to be moving - thereafter however, the remainder of the engine's thrust is available for the imparting of speed.
Videos of them static are almost silly, as visually there's nothing much going on!
The noise is insane - I could be standing down the end of my street, and at full throttle, it could well be a full-size small jet aircraft taxiing.
Videos of them static are almost silly, as visually there's nothing much going on!
The noise is insane - I could be standing down the end of my street, and at full throttle, it could well be a full-size small jet aircraft taxiing.
Ha ha!! Well - just be glad that this project has gotten out my system the need to itch the other scratch I had, to stick a helicopter turbine in a Landrover (I had a 110 Defender for quite a few years) - I even had that fantasy down to calculating how much intake volume the sliding rear windows would allow, etc!
I've been into jets (& lasers, as it happens) ever since I can remember, and even did a school project on the jet engine when I was 11. I'm conscious that as someone who's 40, I've lived at the same time as the inventor of the jet engine (as far as I know, unless the Greeks or the Arabs really got there first, in BC, or something) - Sir Frank Whittle. Quite amazing, really.
I've gotta sort somewhere decent to test it - my usual grassland haunts are proving to have too much debris for the engine to try to suck up - I'm thinking either Miele vacuum cleaner exhaust carbon filters (which offer virtually no resistance to air movement), or find strips of tarmac to go on instead of said grass, which is what most RC people have to do!
Or, some kind of cowling- but then that would well detract from the ability to see the engine, which I think it part of the novelty.
When it was two-stroke powered, it'd come back covered in grass and crp.
I'll sort videos as soon as can.
I've been into jets (& lasers, as it happens) ever since I can remember, and even did a school project on the jet engine when I was 11. I'm conscious that as someone who's 40, I've lived at the same time as the inventor of the jet engine (as far as I know, unless the Greeks or the Arabs really got there first, in BC, or something) - Sir Frank Whittle. Quite amazing, really.
I've gotta sort somewhere decent to test it - my usual grassland haunts are proving to have too much debris for the engine to try to suck up - I'm thinking either Miele vacuum cleaner exhaust carbon filters (which offer virtually no resistance to air movement), or find strips of tarmac to go on instead of said grass, which is what most RC people have to do!
Or, some kind of cowling- but then that would well detract from the ability to see the engine, which I think it part of the novelty.
When it was two-stroke powered, it'd come back covered in grass and crp.
I'll sort videos as soon as can.
rhinochopig said:
So is the turbine simply a 'pusher' or is it driving the centre diff like the motor would?
Purely thrust alone. The logistics and complications of actual shaft-drive were just not worth the stress - and then with very uncertain outcomes (e.g. would the torque have been enough anyway?).I don't think jets are usually ever (never?) deployed to shaft-drive driven wheels = only props and rotors.
vx220 said:
I think tarmac would help your directional stability!
A consideration, certainly - but those tyres would need to go, for optimised behaviour on tarmac. Even when it was run by the two-stroke, it would skip all over the place and spin its wheels (all four!) on tarmac - of course part testament to how powerful the engine was, but also to lack of good traction.I need to get to know it on grass first, better learning-ground. I've tried it at full throttle now, just once, but got scared as it started off so quickly, after it got past inertia. And I'm not scared easily, as the two-stroke would take it to 40/50mph in a blink, almost.
Slight technical update - it kept on stalling (flaming out) under hard acceleration - so then there's me stressing that reputedly one of the most reliable engines about is not being reliable for me - turns out that the fuel was chucking to the back of the tank, leading then of course to bubbles in line & flame-out. And at full tilt, it'll get through the whole tank in a few minutes or under, so it will almost always have (create) space to let the remaining fuel gather to, away from the pick-up. The same will then happen on steering. Now I see why a lot of other models have tall tanks! Evian bottles will have to serve as a stop-gap.
P.s. Even at a good way less than full throttle, it was clearing a speed significantly faster than with the original engine, so clearing 40/50mph easily. I won't be surprised now if I eventually see it go past 80mph - just need to sort the fuelling issue. I'll likely stick my phone on top of it some time and use the Crank cycling app to discern actual top speed.
And thankfully all that weight meant that if I steered quite hard - it did just as it used with the normal engine - skidded about/spun - but no question of a flip/roll or anything.
P.s. Even at a good way less than full throttle, it was clearing a speed significantly faster than with the original engine, so clearing 40/50mph easily. I won't be surprised now if I eventually see it go past 80mph - just need to sort the fuelling issue. I'll likely stick my phone on top of it some time and use the Crank cycling app to discern actual top speed.
And thankfully all that weight meant that if I steered quite hard - it did just as it used with the normal engine - skidded about/spun - but no question of a flip/roll or anything.
Edited by Arif110 on Sunday 6th July 22:37
MBBlat said:
Chrysler, Rover, General motors would disagree.
http://en.wikipedia.org/wiki/Chrysler_Turbine_Car
http://en.wikipedia.org/wiki/Rover-BRM
http://en.wikipedia.org/wiki/General_Motors_Firebi...
http://en.wikipedia.org/wiki/Fiat_Turbina
Even ships do it
http://en.wikipedia.org/wiki/Combined_gas_and_gas
And before you quibble those are gas turbines not jets, a jet is just a specific type of gas turbine.
http://en.wikipedia.org/wiki/Gas_turbine
No quibbles - glad to be edified!http://en.wikipedia.org/wiki/Chrysler_Turbine_Car
http://en.wikipedia.org/wiki/Rover-BRM
http://en.wikipedia.org/wiki/General_Motors_Firebi...
http://en.wikipedia.org/wiki/Fiat_Turbina
Even ships do it
http://en.wikipedia.org/wiki/Combined_gas_and_gas
And before you quibble those are gas turbines not jets, a jet is just a specific type of gas turbine.
http://en.wikipedia.org/wiki/Gas_turbine
Slight technical update - it kept on stalling (flaming out) under hard acceleration - there's me stressing that the most reliable engine about is not being reliable for me - turns out that the fuel was chucking to the back of the tank, leading then of course to bubbles in line & flame-out. And at full tilt, it'll get through the whole tank in a few minutes or under, so it will almost always have space to let the remaining fuel gather to, away from the pick-up. The same will then happen on steering. Now I see why a lot of other models have tall tanks! Evian bottles will have to serve as a stop-gap.
Fugazi! DUDE!! I gotta be at work right now (paid work/day job) - but will revert later with a deluge of further questions! I worshipped at the altar of jet power ever since I discovered it!
...
(But - P.s. that fuel filter dongle thing, I know it well from two-stroke - but wouldn't it restrict flow to the point of straining the pump's sucking? I hear that the fuel can be sucked so hard and fast that even a solid line of it can be 'pulled apart' releasing the air dissolved in it (cavitation). Hence - anything restricting flow would be a bad thing, no?
It does have a filter within the green housing - and my instinct it to have one at fuel pick-up - what what's your thought on pump-strain?
...
(But - P.s. that fuel filter dongle thing, I know it well from two-stroke - but wouldn't it restrict flow to the point of straining the pump's sucking? I hear that the fuel can be sucked so hard and fast that even a solid line of it can be 'pulled apart' releasing the air dissolved in it (cavitation). Hence - anything restricting flow would be a bad thing, no?
It does have a filter within the green housing - and my instinct it to have one at fuel pick-up - what what's your thought on pump-strain?
Edited by Arif110 on Monday 7th July 13:56
Fugazi said:
Well done op, I have only just seen this thread! I did something similar a few years ago and it was fun for about an hour. You'll find that as you throttle up the car doesn't accelerate as fast as a conventional model. Then in that microsecond between your brain registering the lack of acceleration and your thumb subconsciously administering more power on the throttle control, the car will have begun to reach silly speeds and then the panic sets in. 
My advice, find a big, big flat car park, any obstruction or debris and the car will find it. The FOD guard will stop largish debris but not the fine stuff like sand, which can cause problems, particularly if it is ingested into the bearing cooling flow. Model helicopters operating in dusty conditions will often lower the bearing life due to this, something like you car may have the engine sucking in a lot of dust all the time.
Your problem with fuel pick up would be helped by using a felt clunk pick up, basically a big wad of felt, which acts like a sponge. It may also be worthwhile looking at some kind of bubble trap too.
I love small gas turbines, built my fist engine when I was 15 waaaay back in 1995. Built on the order of around 60 engines in total, both commercial and my own designs. Even made my own lathe when I was young and had no money. I keep a few engines and parts in my desk at uni so when I teach the undergraduate engineering jet engine lab, the students have the chance to hold and inspect real engines. We have some nice sectioned full size engines in the dept as well as a small engine that the students use to take measurements, but they're not allowed to touch them, and much of it is hidden away. The Wren engine you're using is a great engine, I have owned several of them, still have a much modified MW54 that's been constantly upgraded. Here's an old engine of mine that puts out around 130N of thrust at 120k RPM and a picture of a combustor along with compressor/diffuser from a variation of the first engine.
A quickie (to help with further work on it tonight): Debris. Say grass seeds. Now - where exactly does it go? Does it go 'straight through' and get burnt - or does the fact of radial compression mean that debris will get thrown up and into areas you really don't want them, at all? Will it 'hit' things like the igniter? Block the tiny fuel jets? I can be quite anal about mitigating this risk - have bought a load of Halfords car bodywork alu-mesh - but I need to know what harm debris actually does, more than you've noted so far. I don't anticipate ever letting it near sand (not even as a two-stroke) - so out-&-out abrasion/abrasives I'm less concerned about. My advice, find a big, big flat car park, any obstruction or debris and the car will find it. The FOD guard will stop largish debris but not the fine stuff like sand, which can cause problems, particularly if it is ingested into the bearing cooling flow. Model helicopters operating in dusty conditions will often lower the bearing life due to this, something like you car may have the engine sucking in a lot of dust all the time.Your problem with fuel pick up would be helped by using a felt clunk pick up, basically a big wad of felt, which acts like a sponge. It may also be worthwhile looking at some kind of bubble trap too.
I love small gas turbines, built my fist engine when I was 15 waaaay back in 1995. Built on the order of around 60 engines in total, both commercial and my own designs. Even made my own lathe when I was young and had no money. I keep a few engines and parts in my desk at uni so when I teach the undergraduate engineering jet engine lab, the students have the chance to hold and inspect real engines. We have some nice sectioned full size engines in the dept as well as a small engine that the students use to take measurements, but they're not allowed to touch them, and much of it is hidden away. The Wren engine you're using is a great engine, I have owned several of them, still have a much modified MW54 that's been constantly upgraded. Here's an old engine of mine that puts out around 130N of thrust at 120k RPM and a picture of a combustor along with compressor/diffuser from a variation of the first engine.
Fuel-tank upgrade...! Calling them fuel towers!
I was testing them for leakages. Obviously, am drilling 1mm holes in the caps to prevent a vacuum.
Not sure that's quite in line with what Brita had in mind for their product!
The brainwave came to me at night while putting the little one to bed - she was drinking from her own Brita bottle (no filter - we just use it as a washable bottle), and I had my Eureka moment.
She loved that just by filling the one up, the other fills up to exactly the same level!
I think now the fuel-starvation-on-acceleration issue will have been resolved. I'll take pics once installed.
I was testing them for leakages. Obviously, am drilling 1mm holes in the caps to prevent a vacuum.
Not sure that's quite in line with what Brita had in mind for their product!
The brainwave came to me at night while putting the little one to bed - she was drinking from her own Brita bottle (no filter - we just use it as a washable bottle), and I had my Eureka moment.
She loved that just by filling the one up, the other fills up to exactly the same level!
I think now the fuel-starvation-on-acceleration issue will have been resolved. I'll take pics once installed.
Fugazi said:
...You'll find that as you throttle up the car doesn't accelerate as fast as a conventional model. Then in that microsecond between your brain registering the lack of acceleration and your thumb subconsciously administering more power on the throttle control, the car will have begun to reach silly speeds and then the panic sets in. ...
In-fecking-deed sir! Panic is the word! I've taken the 2-stroke engine out now, to make space for the new fuel units - so it should exhibit less inertia/slightly more predictable behaviour....Thankfully also - the Spektrum transmitter has some very elaborate settings, and so here we're talking throttle 'Expo' or I guess 'rate' as we'd call it in the car world.
In Low Range, my Defender's throttle pedal would go 'long' - same thing here - allows a good margin of security of control.
Fugazi said:
...You should also get into the habit of checking fuel, these days I only do research stuff, (developing my own testing and evaluation software for small gas turbines in my spare time) so I don't require gallons of kerosene anymore and just buy small quantities of paraffin from B&Q, (smells lovely, unlike JetA1).
Good stuff - I use Bartoline paraffin - just bought a few bottles today! Key question: two-stroke oil addititive - I'm happy (want) to spend as much as necessary for the 'best' thing - so am currently using Castrol Actevo. Is there any drawback though with using this - as it's fully synthetic? (I'm used to asking the question, as once toyed with the idea of dosing my actual car's diesel with two-stroke, whereby lots of warnings over wrong type of oil).Paul sir (Fugazi),
Any thoughts then on top speed, with 10kg of thrust? The thing weighs about 13/15kg now.
I'm also worried that the car will go out of transmitter range, if actually allowed to get to top speed. I'm suspecting 80mph at least?, based on a very short burst of high power.
Thankfully idle (50,000RPM/300g of thrust) is perfectly balanced with the car's own inertia - so it equates to not moving at all. It begins to move at about 80,000RPM - and it gets rapidly scary at 120,000RPM onwards.
Arif
Any thoughts then on top speed, with 10kg of thrust? The thing weighs about 13/15kg now.
I'm also worried that the car will go out of transmitter range, if actually allowed to get to top speed. I'm suspecting 80mph at least?, based on a very short burst of high power.
Thankfully idle (50,000RPM/300g of thrust) is perfectly balanced with the car's own inertia - so it equates to not moving at all. It begins to move at about 80,000RPM - and it gets rapidly scary at 120,000RPM onwards.
Arif
Fugazi said:
How fast, very fast, stupidly fast.. a simple, back of the fag packet calculation gives a rough estimate of 90 mph. Biggest factor is the drag of the car, which is probably huge as it has the aerodynamic qualities of a chest of drawers. 90 mph may not sound 'that' fast but if you're stood still then it will disappear into the distance at a rate of knots. However I found my car, (looked very similar setup to yours) was very, very twitchy as the speed increased and I ended up just letting it accelerate for a few seconds before spinning it around to dump the speed. If you had a quiet road and followed in a car, you might have better luck
As you've noticed the thrust curve isn't linear, so you can program the transmitter to give a better profile. One thing to remember though, if you do get high speeds is the engine, even at idle, is always producing thrust. Some of the first rc jet engine powered models were unable to land unless the engine was shut down due to this residual thrust. My car wouldn't move at idle, but once rolling the thrust at idle meant it didn't stop. But looking at those tyres I think you'll be fine.
OMG - no, no - 90mph is plenty fast enough!! Even as a two-stroke engined affair, I had to be seriously respectful of its speed (I think 40mph). And - indeed - it has no brakes, I had to decommission the brakes for reasons too long to go into, but it was with experience in mind of the car when it could do 40mph - I could always get away without having to use the brakes, just lapping it instead in a very, very large field (empty, flat country park). It had transmission disc brakes, and if I needed them to operate the car, I'd burn through them quickly, and they're a pain to change, and a consumable I didn't want to get into (discs not always in stock). So again you've inferred totally accurately, that I rely on the car's [what's the opposite of inertia?] proclivity to come to a standstill, because of aerodynamics (lack of) and mud-plugging tyres, and going on grass. And thankfully for me, at idle, the car's not being pushed at all notably - feels almost the same as with no engine on - doesn't want to move. The perfect solution would be 90mph laps, not straight runs. Let's see what lateral traction allows!As you've noticed the thrust curve isn't linear, so you can program the transmitter to give a better profile. One thing to remember though, if you do get high speeds is the engine, even at idle, is always producing thrust. Some of the first rc jet engine powered models were unable to land unless the engine was shut down due to this residual thrust. My car wouldn't move at idle, but once rolling the thrust at idle meant it didn't stop. But looking at those tyres I think you'll be fine.
Edited by Fugazi on Tuesday 8th July 11:58
Videos! Indeed! I'm hoping that it's as easy as uploading photos now? Else - I do have an Imgur account, or could figure out how Youtube works!!! I'm actually a complete Luddite!
I initially wasn't going to record a simple static start & run, but someone here said that that'd do for now/better than nowt - so I'll look to sort that tonight. Obviously, visually, there's virtually nothing to see more than the photographs afford - so here's hoping that the sounds make up for that a bit!
I'll only get around to actual videos of ground runs when I find someone trustworthy enough to do a good video, with me focusing on controlling the thing!
I initially wasn't going to record a simple static start & run, but someone here said that that'd do for now/better than nowt - so I'll look to sort that tonight. Obviously, visually, there's virtually nothing to see more than the photographs afford - so here's hoping that the sounds make up for that a bit!
I'll only get around to actual videos of ground runs when I find someone trustworthy enough to do a good video, with me focusing on controlling the thing!
Quasi-technical update: I'm going to programme the engine to top out at a level of thrust that results in about 50mph. I know I was okay handling it at that speed when it was a two-stroke, but with the current programme, it's so sht-scary approaching the higher engine speeds, that I never even get to cruise at 50, always backing off - so continuously scared of going past that speed (as it's all in the last 20% of throttle trigger travel). This will then allow me the confidence to do a video!
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