Scale flight profile instead of scale modeling?

[mooffle]

A week ago I launched this lego rocket housing Benny from the lego movie and afterward started talking with my dad about scale.
This rocket is impossible to sim in OR but by my estimate flew to ~250ft and over our conversation I mentioned something to the effect of "how high would I have gone if I had been Benny?"
The scale turns out to be pretty close to 1:42, and in human terms Benny went just about 2 miles high. I think this is neat but hardly spacefaring. Taking this same scale I would have to send him up to about 6 miles to get him to a scale distance 'lego ISS'.

Quick other example, the Dr Zooch space shuttle is about 1:200 scale and to hit an 'ant scale ISS' would need to go about 1.25 miles. That's high but maybe the limit of achievable with some extreme mods.

I'm curious, has anyone done something like sending a scale model to a scale distance? Or even a scale payload (lego, army man, toy mercury capsule) and a different rocket?

 

[Ronz Rocketz]

Paratroopers work great in the V2 (at 9:00) as long as they don’t get caught on the backstop.

 

[mooffle]

I have a bag of those guys that I keep forgetting to take with me on launches.
My kid and I throw them as high as we can in the driveway on windy days.

 

[Scott_650]

Interesting. For a long while I dabbled in model railroading. Never managed to finish much of anything other than basic modified ovals of track with some sidings and rudimentary scenery (the skills needed to get even close to what the magazine/video model RR folks can build have a MUCH steeper learning curve than rocketry!). But one subset of the hobby is the people who model operating a RR rather than building a layout - they use compressed time clocks, waybills, train orders, freight manifests, etc to move scaled down consists of cars around the tracks (in other words a couple of hopper cars represents a hundred real world cars since real freight trains even in N scale would be very long) to simulate operation of an actual railroad. Never thought of applying the same logic to rockets but now I am! There’s a fair amount of data available on the performance of our prototypes during real launches - for example I think the data for every post WW2 V2 launch accomplished by the US is readily available online - so now it’s down the rabbit hole to see what it takes to simulate a scale launch. Not including the V2s that exploded of course - at least not on purpose...

 

[Scott_650]

Ok, here’s an example. An ASP 1/67 scale V-2, 13mm motor mount, flying on an Estes BP A10 motor hits, per ThrustCurve.org, 85 meters. That scales up to around 3.5 miles - approximately the apogee of the first V-2 launch at White Sands! Which, unfortunately, did explode. According to the info on the Postwarv2.com site, V-2 Round 2 hit 3.4 miles when the control vanes failed causing a fin to shear off - then the rocket exploded on impact due to residual fuel. So there’s an actual prototype launch you could easily simulate, minus the crash and explosion, of course. The next few rounds hit 65-80ish miles which scales down to over a mile so even if you can get little ASP V-2 to that altitude not likely it’ll ever be found again. Simulating actual flight profiles looks a little problematic unless you carefully cherry-pick your prototype - stepping up to a 1/25 scale V-2 (the rough scale of the Estes #3228 V-2) you’d need an apogee over 14k feet to simulate the lower altitude early rounds - even if you build your Estes V-2 with a 38mm motor mount ThrustCurve only shows you hitting 6647 feet or 31.5 scale miles, less than half the 65-80 miles the early rounds hit. There are V-2 rounds that flew to lower altitudes but those were mostly flights that malfunctioned. Still, an interesting idea if you can find the right prototype.

 

[mooffle]

Interesting. For a long while I dabbled in model railroading. Never managed to finish much of anything other than basic modified ovals of track with some sidings and rudimentary scenery (the skills needed to get even close to what the magazine/video model RR folks can build have a MUCH steeper learning curve than rocketry!). But one subset of the hobby is the people who model operating a RR rather than building a layout - they use compressed time clocks, waybills, train orders, freight manifests, etc to move scaled down consists of cars around the tracks (in other words a couple of hopper cars represents a hundred real world cars since real freight trains even in N scale would be very long) to simulate operation of an actual railroad. Never thought of applying the same logic to rockets but now I am! There’s a fair amount of data available on the performance of our prototypes during real launches - for example I think the data for every post WW2 V2 launch accomplished by the US is readily available online - so now it’s down the rabbit hole to see what it takes to simulate a scale launch. Not including the V2s that exploded of course - at least not on purpose...

This sort of thing is exactly what I was thinking. I've never heard of that aspect of railway modeling, super cool!

 

[Ronz Rocketz]

Vonce ze rockets go up, who cares ver ze come down. Zat's not my department, says Wernher Von Braun.

 

[Cape Byron]

I should get bonus scale points for my Spacemonkey V-2. It looks like it was built in a dimly lit underground tunnel...

 

[Ronz Rocketz]

Filled with oil reserves and slave labor...

 

[Scott_650]

Another quick example - the Estes Mini Honest John #2446 is approximately 1/28 scale, the operational ceiling for the prototype Ho Jo is, according to Wikipedia, 33k feet, if you overclock your model with an 18mm motor mount ThrustCurve shows you an apogee of 1119 feet on an Estes C6 - that scales to 31k feet, plenty close enough for a reasonable simulation. Again, recovery could be a challenge but on a calm day under a streamer your chances are reasonable.

 

[Ronz Rocketz]

Another quick example - the Estes Mini Honest John #2446 is approximately 1/28 scale, the operational ceiling for the prototype Ho Jo is, according to Wikipedia, 33k feet, if you overclock your model with an 18mm motor mount ThrustCurve shows you an apogee of 1119 feet on an Estes C6 - that scales to 31k feet, again close enough for reasonable simulation. Again, recovery could be a challenge but on a calm day under a streamer your chances are reasonable.

I put a D12-5 in a MHJ I got from Walmart for $3 but had to add a ton of weight in the NC. Never saw it again despite putting my email on it.

 

[mooffle]

This seems like it could make for a really good contest, send a scale rocket or even just a scale payload to as accurate a distance you can from an historic flight.

 

[Ronz Rocketz]

Wouldn’t they need to factor in the low air pressure of the upper atmosphere with the real rocket when determining the scale altitude?

 

[Scott_650]

More time rummaging through all the pages and pages of sounding rocket data available on the web shows me that it’s tough to find a prototype rocket (other than missiles, with ballistic flight paths we can’t fly prototypically and stick to the NAR safety code) to scale down for an achievable model rocket launch and recovery...if you only look at apogees. If we switch to motor burn times it’s much simpler.

The big Aerobee 350 had a total motor burn time - booster and sustainer - of just under a minute, 56.1 seconds. The length of the 350 was 55.45 feet so if the model is scaled down to 1/20 that equals 2.77 feet or 33.6 inches. Scaling the burn time rather than the apogee equals 2.8 seconds - an Estes C6-0/B4-4 hits that burn time almost exactly, 1.9 + 1 = 2.9 seconds. ThrustCurve doesn’t do staging so I’ll need to fire up my laptop and do some Open Rocket sims but looking at available 2 stage rocket kits shows plenty of them with this recommended motor combination roughly the size of a 1/20 Aerobee 350.

So motor burn times would be a reasonable basis for scale flight profiles for model sounding rockets rather than altitude, the prototypes simply go too high to use apogee - unless you’re talking about very big launch/recovery areas, dual deploy setups, trackers, etc...that’s a whole ’nother can of worms...

 

[mooffle]

Looking into scaled burn time, I started thinking more about flight events. The Saturn V main booster took the the launch vehicle to 42 mi (wikipedia). At 1/200th scale that's roughly a 22 inch rocket going to 1108 feet. If you made it a mid body separation where the staging happens that seems like a very doable 'event sim'.

 

[Scott_650]

Looking into scaled burn time, I started thinking more about flight events. The Saturn V main booster took the the launch vehicle to 42 mi (wikipedia). At 1/200th scale that's roughly a 22 inch rocket going to 1108 feet. If you made it a mid body separation where the staging happens that seems like a very doable 'event sim'.

ThrustCurve shows the Estes 1/200 RTF SV modded for 24mm motors hits 1107 ft on an Aerotech F12 reload - another good candidate for a scale mission launch. But that’s not taking whatever additional nose weight you’d need into account though I did set the Cd at the maximum value of “1”.

 

[mooffle]

I have a 1/696 micromaxx Saturn V, open rocket reports a 390ft apogee on a 1/2A-3. Scale 1st booster separation is about 320ft. I might have to try this out!

Estes A10 takes it to 570 ft or 75 scale miles. This doesn't mean much as 2nd stage separation happens much later, I just think it's neat.