Originally posted by Johnnie
I assume you have documented this, can you share any more without divolging dead giveaways?
The problem I would have a concern with, are hybrid propulsion having trouble scaling up or down. If you scale down to the levels you have achieved for ease of children, have the costs also scaled? Let me rephrase, how much might your system sell for, if only to school science projects? Granted the Science teacher would only need to purchase one for a class learning assignment. Did you imagine a system simple enough that a pack of Cub Scouts could have a build/fly day like the Estes bulkpacks provide? Personaly I would love to have one of your designs, if only for the novelty of being able to fly a Hybrid off of the low power group.
How about scaling up?For me personaly, an "O" hybrid could nearly meet the standards for a Level 4 certification project, for the sheer complexity it represents. Contrail offers the "O" and has at least had more than one successful flight, and one recorded failure.
Never-the-less, you present an excellent case for ease of use and simplicity. My son has said more than once that he wished he could fly the "farting" rockets. He is very smart, and I believe he can be on one of the mission to Mars trips (not Disney), but until then, he wished for a system that fit his level/age.
Are Whipits scalable? Granted I don't want to purchase a 4-pack of 440cc Whipits, but could the whipit size be doubled without too much trouble? A hybrid in the full E to Low F with ease of use would be nice, especially if my son could load his own ejection charges.
Good reads Doc, thank you!
Johnnie
I'd divulge as much as it took if it'd help get the process going. I can't divulge plans because I don't have them. I designed conceptually, the other guy hacked the hardware to spec within the constraints of the available parts (the electronics came as is -- we had no control over the size).
Price would be at or below $100 for everything, including enough disposables for a dozen flights. Whipit carts would be up to the user, running about 50-60 cents each mail order. Reload grains would be ~$1 each shipped: paraffin poured into kraft paper tube. Each reload would have a burst disk. Instructions for making your own would be included. Home making costs for grains were based on my test and ran 20 to 25 cents each. That was a high melt hard paraffin. Cheaper waxes could be used.
Start with $100, and add $100 for two cases of Whipits and 50 more grains, and you get 82 flights for $200 (or a lot more if you poured your own). That's $2.50 each, cheaper than any D motor. $200 will get you an AT reloadable 24mm case and about 20 E reloads. The cost wasn't a planned factor, but I went in knowing that between commercial Whipit cans and wax grains the result would be a lot cheaper to operate.
The particular design doesn't scale, and wasn't intended to. There's only one size of Whipit, or at least that I was familiar with and designed it around. They work by pushing in on the stem. Other tanks don't. If there are simple, premanufactured nitrous canisters of a larger size, that have a similar mechanism whereby the opening of the can was accomplished by sealing it into the protective container/motor housing and the valve opened by the pressure aplied on the can against a valve stem, then yes this could be redesigned around that. Otherwise, we'd be looking at refillable tanks, which means handling outside the motor. That's the major sticking point with respect to safety, and in comes GSE and all that entails. The motor itself could be longer with no scaling except material costs, but I've no idea how long would be too long for a given core geometry.
This was to be a low D to high E motor, according to different grains and cores. The design wouldn't prevent users from making their own grains out of other materials. They just had to fit. Getting certification would be based on using the manufactured grains.
The recovery mechanism wouldn't require scaling. It's completely transportable, and doesn't require particular electronics so the user could change that.
As for use, yes, it was intended to be usable by minors without adult intervention (supervision being another thing). Making motor grains wouldn't require melting and pouring wax, which can be dangerous, though not terribly damaging. You can pour wax pellets into the molds and melt them in an oven. Again, adult supervision, but not intervention.
