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Can this get stickied? Might head off similar threads in future!I would strongly recommend a few G flights before your level one, and from there I would recommend a nice low and slow H flight.
Can this get stickied? Might head off similar threads in future!I would strongly recommend a few G flights before your level one, and from there I would recommend a nice low and slow H flight.
Several files posted on Rocket Reviews:I ended up going with the Excel for my L1. My question is does anyone have the 4 in open rocket file for it? I can always make it myself as well.
Thank you very much!!
Quality components in there.Dragon Slayer is a good L1 kit. https://dragonrocketry.com/products/4-dragon-slayer-l1-kit
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I would have thought you would want a 54mm retainer if you have the 54mm kit?I bought the 54 mm kit but am unsure if I should also get a 38 mm retainer. Would it be better to do this?
The word you’re thinking of is “adapter”, I think. The adapter allows you to use a narrower motor, the retainer prevents your motor from ejecting itself out the rear of the rocket.I bought the 54 mm kit but am unsure if I should also get a 38 mm retainer. Would it be better to do this?
Just fly what you want in the certification rocket. It is your cert and you can choose any motor in the H-I impulse range. If your rocket, as you have built it, should be capable and the flying field is appropriate then just choose a motor.If I were to make a recommendation on motor selection, I’d say your best bet is an H motor (available in 29mm and 38mm diameters) with strong but not excessive thrust.
I think SMS is correct. You are probably looking for a motor adapter. The retainer simply holds the stock size of motor in the tube while an adapter can hold a smaller motor in the stock sized tube. You can make your own adapter or purchase one from Aeropack or Giant Leap Rocketry. Look for a 54mm to 38 mm adapter.The word you’re thinking of is “adapter”, I think. The adapter allows you to use a narrower motor, the retainer prevents your motor from ejecting itself out the rear of the rocket.
There is some overlap in 38mm and 54mm impulse ranges. 38mm runs mostly G through J, 54mm runs mostly I through L. “Mostly” because Loki manufactures two 38mm K loads and a single 54mm M load.
If I were to make a recommendation on motor selection, I’d say your best bet is an H motor (available in 29mm and 38mm diameters) with strong but not excessive thrust. You don’t want to send the rocket too high or overstress it. There’s no need for the flight to be super impressive or break performance records, it just needs to be nominal, safe, and recovered without damage.
I meant adapter Woops!I would have thought you would want a 54mm retainer if you have the 54mm kit?
I would also be making or buying an adapter, 54mm downto 38mm, to give more flying options. That gives you choice of two motor sizes to fly.
The Excel is also a classic. Excellent (pun intended) choice.Well, my rocket is finally done and ready to fly. I put it off for a long time and going out to fly it on Saturday. Ended up doing an Excel Kit and I really think it turned out great. Got a 54 mm kit, with a 38 mm adapter and planning to put an H100 in it. I think the paint turned out amazing and really excited to fly it. Here she is in my shop class, flying it with the rest of my class who are bringer there Level 1s. Only about 5 people so it should be nice.
She's a beauty, @1Matthew !Well, my rocket is finally done and ready to fly. I put it off for a long time and going out to fly it on Saturday. Ended up doing an Excel Kit and I really think it turned out great. Got a 54 mm kit, with a 38 mm adapter and planning to put an H100 in it. I think the paint turned out amazing and really excited to fly it. Here she is in my shop class, flying it with the rest of my class who are bringer there Level 1s. Only about 5 people so it should be nice.
That's great !Going out to Lucerne Dry Lake Bed. Waking up at 4:30, driving to school. Going to be a long day but super excited!!!! Don’t have a name for her yet. I’m planning to fly on an H100, low and slow. After this I’m hoping to build something bigger with a group of my classmates and would like to build something for some altitude within the level 1 range but that’s getting ahead of myself.
Thank you!That's great !
Lucerne is one of my favorite sites and the people at ROC are a great group.
Good luck again !
-- kjh
Check the rail length in your sim, but 35fps is too slow, and if your sim is .6 lbs underweight then your real speed will be even slower.I've simmed the Excel with the H100 and Im getting around 1490 ft with a speed off the rail at 34.7 ft/s. Weighed my rocket today in the shop with the motor at 4.06 pounds, a bit heavy. Without the motor Open Rocket says it 3.43 lbs. My concern right now is parachute sizing, I think there is a 36" chute in my rocket, which should be large enough but with that Im getting a ground hit velocity at 23.6 ft/sec which seems fast. Do I need a bigger chute?
Time to pick out a different motor? I know my shop teacher just bought a bunch of H100s but they seem too slow. Ive talked with my peers who are also flying with me and they are getting slow off rod velocity as well.View attachment 618622
This was my sim, I have a piston ejection I added on the kit, I can't seem to get the velocity higher, I know some of my parts weights are off, I tried to find some of the info online and a lot of the stuff I just did not weigh. my ground hit speed is also high. This is on a 36 inch chute. My dry weigh is still slightly off. Not sure what to do. I followed the Excel's instructions, so it should fly fine, but sim says otherwise?
View attachment 618622
This was my sim, I have a piston ejection I added on the kit, I can't seem to get the velocity higher, I know some of my parts weights are off, I tried to find some of the info online and a lot of the stuff I just did not weigh. my ground hit speed is also high. This is on a 36 inch chute. My dry weigh is still slightly off. Not sure what to do. I followed the Excel's instructions, so it should fly fine, but sim says otherwise?
I feel bad raining on your parade at the last minute, @1Matthew
The end of the semester is approaching and the ROC launch is Saturday.
Is there a deadline for your flight ?
I don't recall ever seeing an H100W back in the days when I was flying a lot in SoCal but the thrust profile of the H100W looks very similar to a G74W -- slightly progressive where peak thrust is about half-way thru the burn.
This is a GREAT profile for a light rocket but not so great when a heavier rocket leaves the rail at a low speed and is then subject to weathercocking and gravity turning -- and all this is happening while the motor is still coming up to full thrust !
The H550ST will definitely work but there is also a Blue Thunder DMS H219T motor with the same total impulse ( and price ) as the H100W.
The H219T is a typical Blue Thunder motor with a slightly regressive thrust curve ( full thrust at ignition and then it tails off toward burn-out ).
How does the H219T Sim ?
HTH.
-- kjh
EDIT: p.s. I used to land at 25 ft/sec on Lucerne Dry Lake bed -- it depended on how windy it was that day.
OTOH, if I was going for a certification, I might try to land a just little softer than I normally would ...
Windy says the Saturday should be a nice calm day and you're young: Windy: Lucerne Dry Lake Bed - 34.51735349402785, -116.96703787455668
Thrust off the pad is more important to a successful flight than impulse. Does ROC have an on-site vendor that you can buy a motor and/or chute from?If I was a little concerned about an H-100 (ish), I'm including H135's, H115's....., I would Recommend what you suggested, but will throw an H-283 (38mm) into the mix. It has slightly less total impulse than the 219, but a very similar motor. The 283 also has less impulse than an H-100 from recollection, but has more than double the thrust at the go.
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