Hi-Flyer xl

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Rex R

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some thoughts, and observations(pictures later). In a recent bit of building I'm doing Hi-Flyers (in bt-20 and bt-70 sizes) I decided to add a bt60 version to round out the fleet plus I wanted to pad out an order, I bought an Estes Hi-Flyer XL.
general observations;
the provided fins are cut from medium hard balsa. the tube coupler is reasonably long(at 3"). pick-nitters might argue that it isn't exactly an upscale since this version is longer than it should be(31" vs 28") however, after 'building' a design file I quickly found a possible reason and agree w/ the decision, the added length is needed for stability(you really don't want to over do the glue, really). even with the added length the stability margin is cutting it fine, to help combat this I've decided to add a 5060 centering ring to the forward end of the coupler as a chute shelf.
one thing I did not see in the instructions is any reference to fin filets...weight savings perhaps? current design file attached, please note that it reflects the modified version that I'm working on.
Rex

View attachment hi-flyer_xl_modified.ork
 
Thanks for the .ork file!

Since coming back to rocketry, I haven't found too many current Estes kits that seem to me to be as "iconic" as the ones I remember as a kid (like the Goblin, the Cherokee-D, and the Omega) but the Hi-Flyer XL has been one that has appealed to me...it is sitting in my build pile right now.
 
Hey Rex,

When I opened your file, I noticed that you were using a simple ogive nosecone (without the blunt tip that the PNC-60RL really has). When I replaced it with my sim of the PNC-60RL the stability moved from 1.14 calibers to 2.01 calibers. I also tweeked the body tubes (unchecking the automatic box).
You can see if it works better for you.

I've also got a sim of the Hi-Flier in the works, but I'm not finished with it yet (still need to work out a lot of the details). FWIW here's a screen shot.



Mind you, my length is at 31.5", yours is at 30.75" (with my nosecone), and the website says it's 31.0". As for my length, I don't remember where I found the lengths on the body tubes (whether online, or from my personal sample (which is lost in the shuffle)). So I might have the wrong lengths for the body tubes. I checked RocketReviews .ork file, and Bubba Davies has them at 1.25", you've got them at 1.188" (presumably 1.1875"), and I've got them at 1.5625". Before I commit and upload my personal .ork file, I'm going to need to verify which (if any) of us is correct.

(PS: Below is R-Rex's .ork file with the nosecone updated)

View attachment hi-flyer_xl_mod PNC-60RL.ork
 
Last edited:
oops, my bad. the bt length is off, they are actually 11.25" in length instead of 11 3/16", total length now stands a whisker under 31". mass figures are measured, not calculated so they may vary a bit from kit to kit. I'm going to have to weigh and measure the cg once it is done anyway but, for now these ballpark numbers give me a notion of where things are going :).
 
oops, my bad. the bt length is off, they are actually 11.25" in length instead of 11 3/16", total length now stands a whisker under 31". mass figures are measured, not calculated so they may vary a bit from kit to kit. I'm going to have to weigh and measure the cg once it is done anyway but, for now these ballpark numbers give me a notion of where things are going :).

Thanks for checking the numbers again...

I've updated my sim and I'm still getting a better than 2 calibers of stability. I should also add that my "fins" are thicker than yours due to my adding the "decals", I've got the rocket "loaded" with a E9-8 motor....

Ohhhh.... you've over-ridden your weights, and I haven't... Hmmm I wonder how much that will change things.... hmmmm.
 
found a nother couple of things fer your sim, nose(transition) assembly cg @ 5.75" and your(nose assy) mass didn't match my reality, mine has a mass of approximately 28g(well 27.8g close as my scale goes)...:).
Rex
p.s.
just installed the motor mount.
 
nope it is not, that is what I was given for a motor tube. OR uses the motor case length w/o the aft closure, and no I didn't use a motor hook for the sim(figured I would account for that when I do the finished cg), also not accounted for is the two wraps of safety wire to wire the hook:).
Rex
 
I played around with a design for an upscaled 3" fiberglass Hi Flyer and found similar issues with the stability - I think the fin shape adds a lot of weight for lower impact on CP compared to other designs which makes the stability an issue.
 
I noticed that when I was planning the 3x flyer, the cp moved aft when I scaled the fins down 10%.
couple of photos of the build. the end view shows the chute shelf attached to the tube coupler.
Rex

hiflyers 001.jpg

hiflyers 002.jpg
 
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