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Descent too fast for an L1 cert flight?

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rocketsam2016

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Hi folks,

TL;DR: Is 23fps descent too hot for a fiberglass L1 cert at MMMSC (grass) using a chute release? Does answer change given plan to eventually add mounted electronics (i.e. fragility and weight) for more traditional dual deploy? Details below


I'll be attempting my L1 on Oct 1 with MMMSC, launching a madcow 4" fiberglass little john on a CTI I236BS (38mm adapted to 54mm motor tube). An H would've been better, but I was able to get a cert special through Apogee and they were sold out of 38mm CTI Hs I could use (can't use skidmark or vmax).


I have a chute release that I will probably use unless it is dead calm since the rocket sims to around 2k feet on this motor. I have some plans for how to modify the rocket for a true electronic DD setup with a tender descender that I think will probably add about a pound, but I'll only embark on that after the cert flight. I'll start a separate thread with those plans to get feedback.


In my enthusiasm I bought a 36" classic fruity chute when I bought the kit (since I saw that madcow offers the kit with a 36" option) and now I'm worried it's a little small. I haven't added fillets yet, but even so I loaded the rocket up and had to add a bunch of nose weight to get the CG 1.25-1.5 calibers ahead of the CP, so my guess is this thing is going to weigh 6.5 pounds at apogee. The fruity chutes calculator says that'll be 23fps which seems a little hot for a cert flight and needlessly fast with a chute release and/or future electronic dual deploy. On the other hand, it's a fiberglass build so maybe it's OK?


So, the question is - should I just bite the bullet and return the parachute for a bigger one, especially given my plan to add electronics to the rocket down the line? Or is 23+fps with a heavy duty fiberglass build no sweat for MMMSC (which is mostly grass IIUC) even on a cert flight?


Thanks!
Sam
 

Flyfalcons

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I'd go bigger, that's just me. The Chute Release removes the need to compromise between touchdown speed and drifting into the Atlantic.
 

Nick@JET

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I'd go bigger, that's just me. The Chute Release removes the need to compromise between touchdown speed and drifting into the Atlantic.
Agreed, you could do it and risk a little damage and likely pass. Just buy a 4lb rocket - you will use that 36" soon I'm sure
 

rocketsam2016

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I probably can't justify keeping it and getting another... it's nearly a $100 chute and my next projects will probably only get larger than this given that I want to try big(ger) motors and I live in New England....

Maybe I shouldn't splurge on the fruity chute when I get a larger chute? They are so nice though... and my DD plans will have the main chute in a deployment bag inside a 6" long 3" tube so the small packing size may be important.
 

Zebedee

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Is your 6.5lb the burnout weight or the full weight of the pre-ignition motor? If it's burnout weight I also vote for getting a bigger chute. Spherachutes do a 60" hemispherical for $62 which packs down to 3x3x4.25". I have one - it's a nice chute.
 

KenRico

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Madcow recommended the chute fit with the rocket ..so ??

I was following the Drago EX discussion about L3 cert and Wildman recommended the 50" Recon for that rocket , and the discussion continued - although I thought that recommendation fit well.

The mfg recommendations are fine. Contact Mike @ Madcow if he has a better recommendation voice ..and you can exchange the 36" fruity for something more appropriate...

My 5lb+ 4 inch Patriot has come down on some PML 48 and 54 inch chutes without trouble .

You could do the cert flight with just the 36 and let it pop at apogee - it shouldn't drift out of range and save the DD for your bigger motor flights after the cert is done .

Kenny
 

cerving

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FG can take a lot of beating, as long as nothing is going to be damaged at 23 fps then it's OK. There's no requirement for a L1 other than getting the rocket back in flyable condition... they don't need to see simulation data first like they do for a L3.
 

KennB

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You could do the cert flight with just the 36 and let it pop at apogee - it shouldn't drift out of range and save the DD for your bigger motor flights after the cert is done .

Kenny
Kenny, while the field is a sod farm that offers lots of area that could sustain a safe landing with the 36" chute (and some spots that might be a little harsher), it is surrounded by tall trees and ponds. Depending on winds aloft, the area of the field we will be able to set up on that day and some other variables, the use of a chute release isn't a bad idea. Sam is taking the right approach in seeing what the conditions are that day and making decisions from there.

Sam, check with Robert and Gloria at AMWProX about the availability of the H-impulse motor you'd like to use. They or Jason will be on the field that day and may have the CTI reload you'd prefer. A lower apogee will make your cert easier for you and safer for the rest of us.
 

les

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If you are landing on a grass field then FG is fairly forgiving. If it was something very hard (like concrete) then you might want to get a bigger chute to slow it down
 

rocketsam2016

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Zebedee - 6.25-6.5lbs is my current best guess at final burnout weight, based on loading the unpainted unfilleted rocket up with everything but the motor propellant and weighting the nose to get 1.5 calibers of stability.

KenRico - Good idea about talking to Madcow. The 36" inch is just what they offer as an optional addon on their site (I bought my kit though a different source). The thing is, I know I'm building a little heavy due to being conservative for my L1 cert (liberal rocketpoxy, swapped eyebolt for a forged one, using quicklinks and the 1/8" ones didn't fit my nose or body eyebolts :/, aeropack retainer and 38mm adapter, conservative CG) as well as a few things to prepare for eventual DD ideas (added a bolt to the forward CR to which I can later attach an allthread rod), didn't epoxy on the nosecone bulkhead and instead used an allthread rod epoxied with great gusto and prep :) into the nose cone.

KennB - I've been in touch with the folks at AMWProx and will be getting my loads from them in the future since they are onsite. They don't have any 38mm H that work for me in stock right now, though they may get some in a few weeks and they'll let me reserve and buy it at the field if they get one. Regardless they couldn't offer the cert special (getting the case for free) so I was committed to Apogee for the initial purchase.

It sounds like the consensus is leaning to go bigger then? I suppose if I go that route I might as well jump up to 48" fruity in case it gets heavier on me again :) and a 48 incher is more likely to be useful for me in whatever I build next. Any thoughts on 48inch classic vs 36 iris? Or strong feelings that I should just go cheaper and get a skyangle or sphera?
 

My Gypsy

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I did my L1 with the same kit and used a 42" Classic Elliptical from Fruity Chutes.

lc071115_12.jpg
 

noffie79

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I love my Fruity Chutes. They look great and pack easy, but they're definitely a premium when it comes to cost. For my L2, a 4" Madcow PAC-3, I used a 44" LOC Angel chute. The rocket weighs 7.5 pounds flight ready minus the motor. Awesome chute at a decent price. Rocket doesn't even look like it's been flown.
 

rharshberger

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If you need a larger chute, do you have a friend in your club who can loan you one? I flew my L3 test flight on a Skyangle XL but, borrowed a Skyangle XXL for the cert flight from a friend. The smaller chute worked fine but the larger one was insurance.
 
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rocketsam2016

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rharshberger - I'm new to the club (and new to HPR - I built and flew a ton of LPR and one MPR up until the early 2000s, and then broke back out my MPR a year or two ago and flew on some bigger engines, then bought and launched an Apogee Aspire in rural CT while visiting family, and now I'm hooked and bought the Little John and an endless stream of things to go with it:) ).

I'd sort of prefer to just own the parachute I want to fly to be honest. I bought the 36" thinking it'd come down a bit fast but that'd be ok (I didn't have the chute release when I bought it so I erred on the fast side). Now I have a chute release and DD plans and the rocket is heavier than I expected. I started this thread to get a sense of whether I was being paranoid or I should just bite the bullet and upgrade.

On other note, wow this forum is awesome. Thanks folks for piping up so quickly! I'm pretty impressed by how helpful the rocket community and companies seem to be - it's a great experience for someone getting back into the hobby and expanding their horizons.
 

SaturnV

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The smaller chute worked fine but the larger one was insurance.
With larger parachute landing is more beautiful and safer for the rocket. However, should be selected for launch day with almost no wind. Otherwise you will watch the movie "Gone With the Wind" with your rocket in the title role. I've seen this movie two times. It is not pleasant.
 

rharshberger

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With larger parachute landing is more beautiful and safer for the rocket. However, should be selected for launch day with almost no wind. Otherwise you will watch the movie "Gone With the Wind" with your rocket in the title role. I've seen this movie two times. It is not pleasant.
The difference in descent velocities between the two chutes was about 5-7 fps. Normally around where I live we have plenty of thermals to deal with.
 

kidrobo

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Anecdotal, but I run a 30 inch main chute with a 15ish inch drouge in my Dartkstar 2.6. With that config OR sims the ground hit velocity at ~9.4 m/s or 30 fps. Flown it three times now and the rocket looks new aside from some dirt on the fins. This is flying at the Mansfield, WA field landing in shitty shrubs and on hard packed dirt. I am using an Aeropack retainer so that is probably taking the brunt of the landing.
 

KenRico

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Zebedee - 6.25-6.5lbs is my current best guess at final burnout weight, based on loading the unpainted unfilleted rocket up with everything but the motor propellant and weighting the nose to get 1.5 calibers of stability.

KenRico - Good idea about talking to Madcow. The 36" inch is just what they offer as an optional addon on their site (I bought my kit though a different source). The thing is, I know I'm building a little heavy due to being conservative for my L1 cert (liberal rocketpoxy, swapped eyebolt for a forged one, using quicklinks and the 1/8" ones didn't fit my nose or body eyebolts :/, aeropack retainer and 38mm adapter, conservative CG) as well as a few things to prepare for eventual DD ideas (added a bolt to the forward CR to which I can later attach an allthread rod), didn't epoxy on the nosecone bulkhead and instead used an allthread rod epoxied with great gusto and prep :) into the nose cone.

KennB - I've been in touch with the folks at AMWProx and will be getting my loads from them in the future since they are onsite. They don't have any 38mm H that work for me in stock right now, though they may get some in a few weeks and they'll let me reserve and buy it at the field if they get one. Regardless they couldn't offer the cert special (getting the case for free) so I was committed to Apogee for the initial purchase.

It sounds like the consensus is leaning to go bigger then? I suppose if I go that route I might as well jump up to 48" fruity in case it gets heavier on me again :) and a 48 incher is more likely to be useful for me in whatever I build next. Any thoughts on 48inch classic vs 36 iris? Or strong feelings that I should just go cheaper and get a skyangle or sphera?
The nice thing about talking direct to Madcow, if he agrees that a bigger chute would be better is that he can exchange the one already sent ..paying freight on next up chute should be decent.

I like the skyangles ..the Wildman Recon comes from them - I have been flying them for a while now. Adding a new size when needed and now have the 24" drogue , 30 40 & 50 inch and the 50 is just starting to show some wear after 4 years .. the swivel adds some value too ..

Kenny
 

Crazyrocket

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The other option is to get a top flight recovery chute. You can get a fairly large chute at a fairly low cost. Although I like the fruity chutes, they are expensive compared to TFR chutes. As long as it will fit in your rocket, it is another option.

I routinely drop my rockets at 25 - 30 ft/sec on a sod farm. As long as the fins are glued on well, it should not be a problem. Just my 2 cents.
 

Banzai88

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If you find you can't use it, and can't return or exchange it, sell it here in the yardsale. New, never flown should put you out no more than shipping. Motor hardware, electronics, parachutes, and to a lesser extent nose cones don't spend much time hanging around at all when offered up for sale.
 

Spicer007

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The size of the chute you use also depends on the size of your recovery area and if the landing surface is rocky hard pan or pasture. IMO, your 36" Fruity Chute should land the 4" FG Madcow, without damage on a grassy field. My preference is to get'em down quickly...

Good luck on your certification flight!
 

rocketsam2016

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Starting this thread was bad news :) I'm now pretty close to just pulling the trigger on swapping for a 36" iris ultra: it supports the weight, looks awesome, and will pack tight for my space constrained future DD modification.

Any reason to worry about an iris ultra used with a chute release? I don't see any reason it'd be more likely to hang up.
 
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