- Joined
- Nov 8, 2021
- Messages
- 129
- Reaction score
- 106
Currently planning a couple of clusters where I would like to use a mix of Klima composite and BP motors, but am aware of the potentially longer ignition time on composites, meaning the thrust curve will have a lag compared to fast igniting BP.
Just to spell out what I think that means (in case I am not quite hitting the nail on the head)... if the composite and BP starters all ignited simultaneously from one electric supply (or tape match from a single electric starter), then the BP motors would achieve pressure and thrust earlier than the composite... which could have a few implications, for example if the BP early thrust peak gave enough of a kick to get off the rod, but didn't have enough plateau thrust then the model could take off but then stall and be non vertical when the composite thrust kicked in. Which might be "sub-optimal"
Or with a bit of luck, the igniter might have pulled out of the composite before it took
I'm aware that Klima products have less availability outside Europe, so will be less experience to tap into but hoping someone may have some pointers, or possibly a vid. Had a search on the forum but didn't find anything specific to Klima.
My understanding is that, unlike many composites (but like Cesaroni), Klima motors have an integral BP charge which is ignited by the starter, meaning less considerations with ignition because the BP takes easily. Or they can be ignited with a BP igniter stick for the same reason.
What I don't know is what the typical lag between starter ignition and beginning of the thrust curve (motor pressure) is.
I think there is plenty of info on BP ignition delay including videos I have made where starter ignition is very clear due to using match tape, although I appreciate there are variabilities. I have a note to do the same next time I launch a Klima.
The launches I am looking at for now are low risk due to the set up, ie the outcome should not be problematic if there is a big delay with the composite.
I'm also thinking of trying an indirect ignition of the BP, whereby tape match is ignited from composite exhaust (close to the composite nozzle but not touching the starter), which in turn starts the BP so that any initial lag is removed. There would be limitations on how well this would work depending on the actual pressure lag, and until proven I'd only try it for launches where the model will launch fine without the BP (and obviously subject to RSO being happy).
Any thoughts greatly appreciated!
Just to spell out what I think that means (in case I am not quite hitting the nail on the head)... if the composite and BP starters all ignited simultaneously from one electric supply (or tape match from a single electric starter), then the BP motors would achieve pressure and thrust earlier than the composite... which could have a few implications, for example if the BP early thrust peak gave enough of a kick to get off the rod, but didn't have enough plateau thrust then the model could take off but then stall and be non vertical when the composite thrust kicked in. Which might be "sub-optimal"
Or with a bit of luck, the igniter might have pulled out of the composite before it tookI'm aware that Klima products have less availability outside Europe, so will be less experience to tap into but hoping someone may have some pointers, or possibly a vid. Had a search on the forum but didn't find anything specific to Klima.
My understanding is that, unlike many composites (but like Cesaroni), Klima motors have an integral BP charge which is ignited by the starter, meaning less considerations with ignition because the BP takes easily. Or they can be ignited with a BP igniter stick for the same reason.
What I don't know is what the typical lag between starter ignition and beginning of the thrust curve (motor pressure) is.
I think there is plenty of info on BP ignition delay including videos I have made where starter ignition is very clear due to using match tape, although I appreciate there are variabilities. I have a note to do the same next time I launch a Klima.
The launches I am looking at for now are low risk due to the set up, ie the outcome should not be problematic if there is a big delay with the composite.
I'm also thinking of trying an indirect ignition of the BP, whereby tape match is ignited from composite exhaust (close to the composite nozzle but not touching the starter), which in turn starts the BP so that any initial lag is removed. There would be limitations on how well this would work depending on the actual pressure lag, and until proven I'd only try it for launches where the model will launch fine without the BP (and obviously subject to RSO being happy).
Any thoughts greatly appreciated!
), but will look into finding somewhere with a bit more space, including possibly getting to the range a bit early on a flying day...
They work as a Thermalite substitute. It does not speed up with sheathing like Thermalite does.
