Silane for air-starting?
 

Thread title says it all. Has anybody tried this on a turbine that would normally use propane as a starting gas?

RE: Silane for air-starting?
 

Because it could prove disastrous!!
"Silane is also used in supersonic combustion ramjets to initiate combustion in the compressed air stream. As it can burn using carbon dioxide as an oxidizer it is a candidate fuel for engines operating on Mars.[8] Since this reaction has some byproducts which are solid (silicon dioxide and carbon) it is applicable only to Liquid-fuel rockets (with liquid carbon dioxide) ramjets, or other external combustion engines ."

John S.

RE: Silane for air-starting?
 

Yes, I'm well aware of what silane is and what it's used for. I've been involved in it's use in the past. It's not like I started the thread after firing up a random word generator. What I'm wondering about is it's potential for *quickly* starting a turbine. 1 minute is just too damned long for an air-start!

RE: Silane for air-starting?
 

Hmm .. if the OP knows anything at all, he's a troll. If he does not, I guess it's humorous, since the relevant facts regarding utility and toxicity are not very hard to comprehend.

Yes, Silane is also fairly toxic .. ask anyone from the semiconductor business how carefully they handle the stuff.

Dave

RE: Silane for air-starting?
 

So educate me.

The vehicle in question will be boosted to Mach 0.3-0.4 wherein a turbine engine will take over. As the vehicle is really just a subscale model being built on a shoestring budget (shoestring is relative, I concede) I'm trying to use consumer level products (ie, COTS) to keep costs down. But as I understand it, consumer level turbines have a start up protocol that takes about a minute to complete. This is unacceptable to me. I am accustomed to small turbines (for me, small means 500 lbf thrust) that start up in 3-5 seconds.

Fast start up CAN be done. The question is can it be done with a minor tweak to a consumer level turbine. It occurs to me that replacing propane with silane may kick the normal start up procedure in the proverbial ass and get things moving in something that resembles a reasonable time frame. I wonder this because a simple gas replacement is trivial. If, on the other hand, large modifications are required to get a quick start up, well then I may as well abandon the consumer level approach.

But while I have access to world-class minds on many topics inherent to the implied topic, my sources aren't used to dealing with consumer level hardware. Thus, I come here to ask questions.



(FWIW, my prior exposure to silane is usage as an ignitor for a vitiated air blowdown facility)

RE: Silane for air-starting?
 

One time long ago, when I was running air start engines, a know it all spectator asked me (in all seriousness I might add), why we didn't spin our engines up on dry nitrogen instead of compressed air. After all, he said "Dry nitrogen is cleaner than compressed air, and won't introduce any water vapor into the engine during the start process".

Duuuuh....
I replied that since dry nitrogen is an INERT GAS, just how in the hell do you intend to start a fire in the absence of oxygen?

You could have cut the silence with a knife..........That was his last question....

RE: Silane for air-starting?
 

I'm not sure I get your point. We're talking about replacing one fuel with another, not replacing an oxygen source with an inert gas.

Or are you trying to imply that silane can't work as an igniter (to which I would have to laugh and wonder why you would assert such a thing given that it serves that function in a number of systems on a daily basis)?

RE: Silane for air-starting?
 

Do you think it a good idea to consult the eng manufacturer before you experiment with exotic gases not designed for said application?

RE: Silane for air-starting?
 

GO FOT IT DUDE !!!!! Light that sucker !!!! My only request is that you have a video camera on a tri-pod ( at a safe distance zoomed in... ) And make your next of kin aware of this RCU thread you started and have them post the video here. !!!!

I love it when a plan comes togeather !!!... ( Quote by Col. "Hannibil" Smith, the A-Team !!! ):D

Kinda reminds me of the movie " Astronaut Farmer "


Danno

RE: Silane for air-starting?
 

Absolutely.

To that end I called JetCat and the first guy I talked to knew what silane was when I mentioned it, but he obviously had very limited knowledge as he kept referring to it as "rocket fuel" (it's not). I asked him a few more questions and he didn't have the first clue of how to answer. I asked him, "If you don't know, who does, and how do I talk to that person?" He named a Bob Wilcox and said to call after 10:30. Only problem with that has been that by 10:30 I've been in the field several hours and quite frankly don't often find myself in a position to have the kind of conversation I need to have (an office environment with a desk and such is nice, yaknow? ...but I'm typically out of my office by 8:00).

I understand Wilcox posts to this board (noticed it somewhere) so I've some hope.

But in the meantime (read: since it's a weekend) I didn't see the harm in asking the hobbyists. If my professional life has taught me one thing it's that often time it's the hobbyists who've tried out the fringe stuff. They have limited budgets and must get creative. Those in the industry often solve problems with money rather than true ingenuity (something that bothers me and I actively try to combat....which is why I'm here hoping that somebody has pushed the envelope).

RE: Silane for air-starting?
 

:)

Here's your hint: I wear two hats at work. When I wear one, I am an "Aerospace Engineer." When I wear the other, I am a "Firing Officer." If there are ever videos to post you'll get it in high def, from six different angles.

RE: Silane for air-starting?
 

I have an airstart turbine that reaches idle in about 15 - 25 seconds after propane lights up, and to me that's a looong time, what turbine model are you talking about? Model turbines only use propane to heat up the combustion chamber because they have no actual fuel vaporizers, not for thrust generation or chamber pressure or anything on that line, can't see how you intend to REDUCE start-up time by replacing propane with some other fuels on a kerosene burning engine, can you explain?

RE: Silane for air-starting?
 

I've been running air start for years- mine start in about 15sec. or less. I'm not sure what motor you're talking about taking 60sec to start up.

RE: Silane for air-starting?
 

the AMT 180 on a buddies roo starts up in 15 seconds or less.. Hell even my old as dirt Ram 1000 autostart that never lights off on the first cycle starts in under a minute..

RE: Silane for air-starting?
 

thats about like the guy at the LHS the other week who asked me why we didn't use CO2... :eek:

RE: Silane for air-starting?
 

The only difference between Mad Scientist and Rocket Scientist is they let the Rocket Scientist play with matches....

Good luck on your endevour.

Danno

RE: Silane for air-starting?
 

By The Way, if you want to REDUCE start-up time on a model turbine, what you need is a way to increase temperature to about 400 degress celsius in one or two seconds and a big electric motor with enough torque capable to reach 35k - 60k Rpms on the turbine rotor real fast, that's past the idle/self sustaining rpm threshold(depending on turbine size), after that you just pump fuel and start accelerating to full power, some full/mid size turbines actually have max power output at that RPM range, while model turbines max RPMS range from about 105k to 240k rpms, so I guess you can now understand why model turbines take longer to start...

RE: Silane for air-starting?
 

IF I WERE TO TRY IT I WOULD STAND BEHIND A BRICK WALL WITH A PEEPHOLE...JUST IN CASE.

RE: Silane for air-starting?
 

Not sure, honestly. On another forum (before I found this one) I was asking questions and folks were talking about a typical start up time for a JetCat (unsure of what model) taking about 1 minute to full throttle. And the idea isn't to increase start up time, it's to REDUCE it. How? Well, as I understand it (and maybe I'm wrong, that's why I'm here asking questions) the propane is used to heat up the combustion chamber. But even that takes time as the propane is lit via a glow plug, you need the right fuel/air mixture, etc. The idea of using silane is basically to short circuit the ignition of the propane. As silane is pyrophoric you have IMMEDIATE ignition of your heater gas. No need to heat a glow plug. No worries about fuel/air mixture (within reason). Just start dumping silane and your combustion chamber is on it's way to hot.

Heck, run a small quantity of silane instead of current to your glow plug and you may be able to go instantly to kero. No need for preheating at all.

RE: Silane for air-starting?
 

Actually, no they don't.

Rocket Scientists hand their toys over to the Firing Officers (that would be me)... Who are the keeper of matches. ;)

RE: Silane for air-starting?
 

And that's why I'm a Firing Officer and you're not.

If/when I were to try it, I'd be standing in an underground bunker half a mile away watching with a camera or five... Just in case.

RE: Silane for air-starting?
 

Sorry, got stuck on to "Increase" twice, my mistake, I meant reduce or "Improve"...

RE: Silane for air-starting?
 

If the combustion of silane produces anything other than non-solid effluent it is not a candidate for use in turbines as the product of the combustion must pass through the turbine. Anything that is other than expanding gasses will damage the the engine.

RE: Silane for air-starting?
 

An absolutely valid point and silane is indeed known for solid combustion products. Oddly enough, in some systems it doesn't seem to be an issue but I'm willing to assume that it is always an issue....But even with that assumption I'm not horribly worried. If the engine lasts 10 minutes I'm happy. As far as I'm concerned it's a disposible item.

RE: Silane for air-starting?
 

http://www.modelaircraft.org/files/0...regulation.pdf

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7. Fuels are limited to kerosene and/or propane unless approved in writing by AMA.</p></font>