Dr. Zooch Saturn V Cluster Mod

Silverfish said:

Having done some research on the internet in response to your replies, I came across this dual engine cluster kit, which fits the BT-60: https://www.modelrockets.co.uk/shop/product_info.php?cPath=50_113&products_id=1279

This may be a far easier alternative, as I wouldn't have to add as much extra nose weight, and it would fit directly into the body tube (not to mention save money on buying motors and igniters!! ). I could then use two of the F1's from the kit either side, and make my custom ones over the two motors, or just leave them with an engine hook. It may not be quite as exciting, but as both would be the same class of motor and have the same delay, I would not have to worry about getting the ejection charges to fire at the same time.

Silverfish

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Above all the clamor Silverfish hears a lone voice in the wilderness say: GO FOR IT! Really!

Yes, I read all the other posts (and understand the logic, especially from Wes) and there are a ton of reasons why it probably won't work, but, I think it can be done. You can be the first. How often do any of us get the chance to be the first one to do anything?

Ok, if you're concerned about a crash and burn, don't be, you won't be riding it and I'm sure Wes can use the business.

Seriously, I suggest doing whatever you want with your first kit, experiment, crash it, and rebuild and fly it again but have fun. Post the results. Then buy another, or 7-8. The best reason to try is because everyone else says it can't be done. If you're concerned about injury to others, fly it alone until you get it right, that's what we do with a new design.

I was told, don't even think of trying to do a 3 stage, 5 to 5 to 1, 11 engine Saturn V cluster but on the 4th try, it worked, chad staged 10.5" apart, twice on the same flight. Just wait until I have time to do my next version.

So, why not try 5 mini motors and take a chance, Columbus did, well, sort of. You know what I mean.

But then, just like Dr. Sue and Sheri, I'm just a girl, what do we know?

Verna
www.vernarockets.com

Verna said:

Above all the clamor Silverfish hears a lone voice in the wilderness say: GO FOR IT! Really!

Yes, I read all the other posts (and understand the logic, especially from Wes) and there are a ton of reasons why it probably won't work, but, I think it can be done. You can be the first. How often do any of us get the chance to be the first one to do anything?

Ok, if you're concerned about a crash and burn, don't be, you won't be riding it and I'm sure Wes can use the business.

Seriously, I suggest doing whatever you want with your first kit, experiment, crash it, and rebuild and fly it again but have fun. Post the results. Then buy another, or 7-8. The best reason to try is because everyone else says it can't be done. If you're concerned about injury to others, fly it alone until you get it right, that's what we do with a new design.

I was told, don't even think of trying to do a 3 stage, 5 to 5 to 1, 11 engine Saturn V cluster but on the 4th try, it worked, chad staged 10.5" apart, twice on the same flight. Just wait until I have time to do my next version.

So, why not try 5 mini motors and take a chance, Columbus did, well, sort of. You know what I mean.

But then, just like Dr. Sue and Sheri, I'm just a girl, what do we know?

Verna
www.vernarockets.com

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Never said it COULDN'T be done, just given that this is like his third kit, it might be a bit more of a challenge than he'd want to undertake at this point. We didn't go from Freedom 7 straight to Apollo 11 in one step; gotta crawl before you can walk ya know! Do research, understand the dynamics involved and what the changes you're making to the design are going to do to it, and how to mitigate the effects of those changes, and then you've got a plan. Doing it haphazardly hoping to get it all right off the cuff without understanding why things are happening is a recipe for frustration and problems. Get and read "Model Rocket Design and Construction" do a cluster bird or two and a couple 'scalers' (OK semiscalers) and maybe save some pennies to buy Rocksim and THEN go for it! Not like he's gotta get a PhD or something first... (though you DO have to get a signed affidavit from Werner Von Braun, Deke Slayton, James Webb, or Alan Sheppard before you can launch the Dr. Zooch Saturn V-- but that's another story )

I've seen your stuff Verna and it's great. KUTGW...

Later! OL JR

Have you built and flown a Dr. Zooch Saturn V? Are you aware of how much nose weight it requires in order to fly straight on just one motor? I looked at your site, and read about your Saturn V's. Right off the bat, you have this to say:
This immediately tells me that your project was in many ways not comparable to Silverfish's idea of clustering a Dr. Zooch Saturn V. First of all, you did your projects with kits that were almost 2.5 times the size of Dr. Zooch's. Have you done cluster-to-cluster staging in a rocket that is 18" tall and based on a BT-60? But much more relevant in the present discussion is the second part of that sentence, the part about having experience building Skill Level 4 kits. Let's review:

• Skill Level 0 is E2x or QuickKit style just assemble and fly type rockets,
• Skill Level 1 refers to kits that may take a few hours to build and which start to require some construction,
• Skill Level 2 kits may require a couple of days to build and require more construction skills, including cutting parts out using templates and cutting tubes to size,
• Skill Level 3 kits will probably require a few days to build and will require the full gamut of model-building skills, and
• Skill Level 4 kits, which require master modeling skills, an understanding of the dynamics of rocket flight and the requirements for a rocket to be stable in flight, to have a safe liftoff and a safe and effective deployment of the recovery system, and to have the ability to problem-solve various design and construction issues and then devise effective solutions or work-arounds for them.
• Skill Level 5 is sometimes also used to describe expert builders ranging from builders of large mid power rockets and anyone who builds high power rockets, expert competition fliers who must tweak existing designs or scratch-build their own designs to create rockets that will be competitive in meets, and designers of rocket-boosted gliders and helicopters, especially those who design and build RCRG's.

Yours and Ray's skills are at Level 5, and I'm sure that there were a whole lot of rockets that both of you built along the way as you progressed to your present level. Silverfish, on the other hand, admits that he has built and flown perhaps a half dozen rockets. My superficial impression is that he is at Skill Level 1. He has made a great start, and seems to be on his way. I was at Skill Level 1-2 for a few years and then started progressing as a result of having a larger budget (meaning that I could build, and gain experience with, many more rockets) and the internet. The inspiration that he had would definitely be a project that would require Level 4 skills, if not more. It would be a daunting task for any of us. We have all applauded him for his ambition, (ambition is what produces the drive for ever greater skill and knowledge acquisition, as you found out yourself with your own projects), and some posters suggested projects that he can do that will give him the experience that he will need in order to be able to tackle the one that he asked about.

I think that I can speak for everyone and say that we are all keen on hearing from him as he progresses and seeing what he comes up with. We have all had dreams of projects that were bigger than what we could accomplish at the time, and nearly all of us still do. It's one of the things that makes this hobby so interesting, so challenging and so much fun.

MarkII

I think that I can speak for everyone and say that we are all keen on hearing from him as he progresses and seeing what he comes up with.
MarkII[/QUOTE]

Absolutely we want to know how it goes. And yes, I realize how difficult it would be to do any kind of cluster with a Zooch kit, and I did have a mis-step or two along the way but as has been said, that's all part of the fun. My only point was, as everyone else's was, always is, to be encouraging. Silverfish already has high expectations for himself and the good sense to ask for help from a forum like this. I think he's got the right end of the stick and will do some great things and have a lot of fun along the way.

Verna
www.vernarockets.com

Hey guys,

Sorry for the lack of updates, because (as I've said before) I live in the UK, I've had to wait for the kit to be sent from America, which has taken some time, but I am pleased to say that it finally came this morning .

Having looked at the kit for the first time, I have to say that it is going to be far harder than I originally thought to cluster, as the nose is already heavily weighted, and it would be a struggle to fit any more motors in (as I do not have access to micromaxx). I am, therefore, going to build this kit as the good Doctor intended, and do something even more daring... even more spectacular... scratch build a cluster !!! I have invested in Rocksim (which, again, is taking a while to get to me) and will adjust my original design on there to get maximum stability (I have attached my concept below, and I will start a new thread on it soon). I will also update this thread as I progress in my build of the saturn .

Thank you all for your advice and support (I have included lots of the information that I have learned on this forum in my concept) .

Silverfish

Definitely, by all means, keep us updated on your new project, Silverfish! And post pictures if you can. (We LOVE pictures! )

MarkII

Silverfish said:

Hey guys,

Sorry for the lack of updates, because (as I've said before) I live in the UK, I've had to wait for the kit to be sent from America, which has taken some time, but I am pleased to say that it finally came this morning .

Having looked at the kit for the first time, I have to say that it is going to be far harder than I originally thought to cluster, as the nose is already heavily weighted, and it would be a struggle to fit any more motors in (as I do not have access to micromaxx). I am, therefore, going to build this kit as the good Doctor intended, and do something even more daring... even more spectacular... scratch build a cluster !!! I have invested in Rocksim (which, again, is taking a while to get to me) and will adjust my original design on there to get maximum stability (I have attached my concept below, and I will start a new thread on it soon). I will also update this thread as I progress in my build of the saturn .

Thank you all for your advice and support (I have included lots of the information that I have learned on this forum in my concept) .

Silverfish

Click to expand...

Sounds good. Good luck and keep us apprised and post pics as you go!

Also, one quick bit of advice from looking at your concept drawing--
Be sure you stagger your motor hooks at least 90 degrees apart from each other, preferably 180 degrees-- otherwise they'll interfere with each other or be nearly impossible to bend past the motor enough to allow extraction of the expended motor without hitting the opposite motor...

Good luck! OL JR

Right, I finally got started building the Saturn V yesterday, so here is my first build post:

Step 1) When I opened the kit, I was struck by just how little it seemed to contain (even after the warnings), and especially by the tiny piece of balsa stock, but I was assured by the instructions that it would be enough, so put my worries behind me and started to build...

The instructions call for you to build the engine mount first, but for a couple of reasons that will become clear later, I decided to leave the engine mount 'till later in the build.

Step 2) Filling and sanding.. well someone has to do it... with some shop brand multi-purpose filler (I am sure that the Elmer's stuff which you guys use is far better, but I cant find it anywhere here in the UK), I started to fill the body tube spirals and the 'Apollo adapter' (the other adapter does not need filling as it is covered by a wrap). I then sanded it all down with decreasing grits of sandpaper, then went to get my can of primer... only to realise that I didn't have any :S, so I put the parts aside and started on the next step until I could go and buy some.

Step 3) Having come to a dead end in the previous step, I moved on to making the engine fairings. I fully expected to have to steam and mold the fairings as I had read on previous threads, but was pleasantly surprised to find that the Doc had come up with a far easier and quicker alternative. All I had to do was to cut the printed raps from the sheet, and glue them to a BT-20. Then when the glue had dried, cut them out (I managed to find a perfectly sized tube to rest the fairings against as I trimmed the edges), and I was left with almost perfectly formed, and very strong, engine fairings.

(I have more to write, but as I am only allowed five pictures in each post, I will start another one.)

Silverfish

Step 4) Step four in the instructions calls for the 'S-II/S-IVB' wrap to be applied to the adapter, having glued the BT-50 'S-VIB' tube to the transition, but seeing as I still don't have any primer, this step will have to wait...

... as well as steps 5, 6, 7, 8, 9....

Step 10) Step 10 is one of the more ingenious steps of the kit, making the F-1 engines . You basically cut out 10 little wraps (five 'Upper' and five 'Lower') from the sheet, and stick all the 'Upper' sections on top of the 'Lower' sections (you only use four on the rocket, but one spare is included in-case any are damaged .... good thinking by the Doc ). Once the glue has dried, you cut out four equal lengths of 'twisted poly coated popeilium', not only making your engines bullet proof , but also creating the look of the 'hatbands' on the real F-1's.

With steps 10-a and 10-b, I deviated from the instructions, which call for you to make some F.G.P. (or funky glue putty) and form it around the engine bells, and then stick a 3/8 of an inch long piece of dowel, with paper wrapped around one end, into it. What I did, was use Milliput (two-part epoxy putty) instead of FGP, and molded a little heat exchange unit instead of using a wrap of paper. It was only after I had spent hours molding each engine, that I realised that they would be covered by the engine fairings :bang:... oh well, I will just have to make a point of turning my rocket upside down and giving a magnifying glass to anyone who looks at it...

Those F-1's came out GREAT! You may, however, have to sand down the turbopumps a bit so that the F-1's will sit level on the thrust structure.

Silverfish said:

Step 4) Step four in the instructions calls for the 'S-II/S-IVB' wrap to be applied to the adapter, having glued the BT-50 'S-VIB' tube to the transition, but seeing as I still don't have any primer, this step will have to wait...

... as well as steps 5, 6, 7, 8, 9....

Step 10) Step 10 is one of the more ingenious steps of the kit, making the F-1 engines . You basically cut out 10 little wraps (five 'Upper' and five 'Lower') from the sheet, and stick all the 'Upper' sections on top of the 'Lower' sections (you only use four on the rocket, but one spare is included in-case any are damaged .... good thinking by the Doc ). Once the glue has dried, you cut out four equal lengths of 'twisted poly coated popeilium', not only making your engines bullet proof , but also creating the look of the 'hatbands' on the real F-1's.
With steps 10-a and 10-b, I deviated from the instructions, which call for you to make some F.G.P. (or funky glue putty) and form it around the engine bells, and then stick a 3/8 of an inch long piece of dowel, with paper wrapped around one end, into it. What I did, was use Milliput (two-part epoxy putty) instead of FGP, and molded a little heat exchange unit instead of using a wrap of paper. It was only after I had spent hours molding each engine, that I realised that they would be covered by the engine fairings :bang:... oh well, I will just have to make a point of turning my rocket upside down and giving a magnifying glass to anyone who looks at it...

Click to expand...

Well done and great pictures keep it up
Cheers
fred

Dr.Zooch said:

Those F-1's came out GREAT! You may, however, have to sand down the turbopumps a bit so that the F-1's will sit level on the thrust structure.

Click to expand...

Yep, I had to do that too, but I used the instructions method of wrapping the paper around the stick to make the heat exchangers. They came out really nice. I couldn't make the FGP work very well (never seems to be a problem when I DON'T need the second skin of glue on my fingers but I couldn't intentionally make the stuff to save my neck!) I ended up using Mighty Putty (or the Walmart no-name equivalent) and it worked really well.

For some reason the 'sticks' on the heat exchangers were a bit long, so I cut them down so they were level with the engines. Worked (and looks) pretty good!

KUTGW!!! OL JR

luke strawwalker said:

Yep, I had to do that too, but I used the instructions method of wrapping the paper around the stick to make the heat exchangers. They came out really nice. I couldn't make the FGP work very well (never seems to be a problem when I DON'T need the second skin of glue on my fingers but I couldn't intentionally make the stuff to save my neck!) I ended up using Mighty Putty (or the Walmart no-name equivalent) and it worked really well.

For some reason the 'sticks' on the heat exchangers were a bit long, so I cut them down so they were level with the engines. Worked (and looks) pretty good!

KUTGW!!! OL JR

Click to expand...

On my build, I used the wood filler and sanded it down to a better shape. I also cut some toothpicks and and pushed them through the forward end of the engine bells and glued them in. Then I made a very small hole in the aft of the sustainer and superclued the engine bells on. So far 8 flights and no engine bell fall offs.

And to bring back up the cluster topic/stability topic. I proved Dr. Zooch right when I installed my fins through the engine cowling for my first couple of flights. That small decrease in CP position (more forward) allowed me to have a great loop-de-loop flight profile.

Having started back at school last week, I haven't had much time for building recently, but, having done all my homework, I sat down and continued with the Saturn V...

The reason that I didn't build the engine mount earlier was that I like to attach the shock cord directly to it, mainly for strength. Because of this, I needed kevlar string for the main piece of the shock cord, which I had trouble finding, but when I did, I built the engine mount (I used epoxy to fix the shock cord and the engine hook in place, again, for strength).

Having now obtained some white primer, I went back to step 4): Stick the BT-50 Tube to the transition, and then glue a wrap over the transition. Simple.

Step 5) You then glue all the wraps onto the rocket, making sure that they are spaced correctly, and that the seams line up (I check on <https://apollomaniacs.web.infoseek.co.jp/apollo/indexe.htm> to make sure that the wraps were placed correctly).

Step 6) Another easy one. Glue the engine fairings to the bottom of the rocket.

Step 7/8) In steps seven & 8, you have to build the Apollo spacecraft and the LES escape tower. I built the whole assembly as one, and then glued it to the nose cone, rather than building it directly on to the cone itself. The LES is made from a dowel, that is sharpened to a point at one end, and then wraps are applied to it to act as the tower base and command module (although I would have preferred to build the tower out of tiny dowels, it would have been way too time consuming and frustrating on a model this size, let alone the fact that it would have been incredibly fragile). One good step that I followed was to build up layers of glue inside the command module, which, when dried, forms a solid cone.

And thats it for another post, when I next get a break from school work I will finish what looks to be a beautiful rocket. Nice one Doc .

Silverfish.

Delta-IV said:

On my build, I used the wood filler and sanded it down to a better shape. I also cut some toothpicks and and pushed them through the forward end of the engine bells and glued them in. Then I made a very small hole in the aft of the sustainer and superclued the engine bells on. So far 8 flights and no engine bell fall offs.

And to bring back up the cluster topic/stability topic. I proved Dr. Zooch right when I installed my fins through the engine cowling for my first couple of flights. That small decrease in CP position (more forward) allowed me to have a great loop-de-loop flight profile.

Click to expand...

I made some "hybrid" Funky Glue Putty by tearing up a kleenex into tiny bits and mixing it with yellow glue to make a pulpy 'dough' that I made two of the engine exhaust ducts from... I must've been getting tired because when I went about making the third batch I screwed it up and it was either too watery or I'd add a bit of paper and it'd get too stiff, and was generally becoming a pain, so I cleaned up and just switched over to the mighty putty.

The mighty putty ducts turned out a little too big, but I found that I could carefully whittle them down to the size and contour I wanted using the hobby knife. I think they turned out really well and I plan to use that technique from now on on such things...

Later! OL JR

Hi all,

I have finally had a chance to finish my Saturn V !!!

I finished steps 9 (sticking the fairings onto the rocket, and then the fins onto them, and applying several fillets of glue for strength) and 11 (glueing various sizes and shapes of dowel and little shaped pieces of balsa on to the rocket to give details such as the ullage motors, AMPs and LOX tunnels, and then applying the waterside decals). I left out the final stage of the build, which involved building the parachute, as I installed a Nomex firewall, and a ripstop nylon parachute instead. All that was left to do was to apply a couple of coats of clear-coat, and there we have it, one completed 'ant-scale' Saturn V rocket!!

And I must say, what a beautiful looking kit it is too, especially the F1 engines, which I am really pleased with. I will try to fly it as soon as possible, and take some photos of its performance, but I am sure it will perform flawlessly. I seriously recommend this kit to anyone wanting to build a scale rocket, and, as soon as I finish my scratch built cluster (see: <https://www.rocketryforum.com/showthread.php?t=6176>), I am going to move on to the Dr. Zooch Mercury Redstone! Thanks for all your help and advice, it has really given me confidence in my build .

Silverfish

Nice job. I have one in a box that I need to build someday. I only hope it will look as good as yours.

--- Ron

Kudos on a really nice job on the Saturn V... looks terrific!

Later! OL JR

Silverfish said:

Hi all,

I have finally had a chance to finish my Saturn V !!!

I finished steps 9 (sticking the fairings onto the rocket, and then the fins onto them, and applying several fillets of glue for strength) and 11 (glueing various sizes and shapes of dowel and little shaped pieces of balsa on to the rocket to give details such as the ullage motors, AMPs and LOX tunnels, and then applying the waterside decals). I left out the final stage of the build, which involved building the parachute, as I installed a Nomex firewall, and a ripstop nylon parachute instead. All that was left to do was to apply a couple of coats of clear-coat, and there we have it, one completed 'ant-scale' Saturn V rocket!!

And I must say, what a beautiful looking kit it is too, especially the F1 engines, which I am really pleased with. I will try to fly it as soon as possible, and take some photos of its performance, but I am sure it will perform flawlessly. I seriously recommend this kit to anyone wanting to build a scale rocket, and, as soon as I finish my scratch built cluster (see: <https://www.rocketryforum.com/showthread.php?t=6176>), I am going to move on to the Dr. Zooch Mercury Redstone! Thanks for all your help and advice, it has really given me confidence in my build .

Silverfish

Click to expand...

You did a great job
Cheers
fred

I launched the Saturn for the first time today, but things didn't go well...

[YOUTUBE]https://www.youtube.com/watch?v=fABdCRYrNak[/YOUTUBE]

When I found the remains, the LES had broken off the nose cone, and more strangely, fin 'A' was missing. The fin did not brake off when the rocket impacted the ground, as I searched the area and could not find it, and if it came off in the air it would account for the strange flight path, but I cannot think of any reason why it would have fallen off in the air....

I will repair the nose cone, and make a new fin, and then decide on a course of action to stabilise it before I try to fly it again...

Silverfish

Once you get that fin glued back on- let's do a quick weight & balance. Cut the shock cord from the adapter at the screw eye. Then stuff the shock cord back into the tube but leave it bunched up near the top. Next get some thread and tie a slip-knot in it. Then loop that around the T60 tube and slide it up and down to find where it balances level. Mark that point and then measure FROM THE LOWER MOST POINT on the T60 tube to your mark (NOT from the F-1s or from the bottom of the fairings.) That distance should be no less than 102 mm.

Also, make sure that you used a standard length launch rod. It should be no less than 34 inches (86.36 cm). The Saturn V, built strictly by the directions does not gain aerodynamic stability until it is 22 inches (~55.9 cm) up the rod.

Finally- there's no telling why the fin came off. Most of us who have been doing model rockets for a long time (since 1969 in my case) have seen many times when a well built rocket with what seems to be very secure fins takes off in a squiggle and a single fin comes fluttering down. Another issue is that builders tend to over build the F-1 engines and under apply the fins because they don't want the glue to show. In looking at your photo of Fin A, however, it looks as if you did a pretty good job in fin application. So I'd blame an inter-dimensional gravity bubble that suddenly changed the laws of physics at some point along the flight path and your rocket just happened to fly through it. Either that or it was witch craft imposed by one of your neighbors- find out which witch is the witch and burn her at the stake. She's probably the one with the wart.

Let me know what parts you need to fully repair your Saturn V and I'll send them to you free of charge- even to the UK.

Wow, talk about good support!!! Thanks for your offer Doc, but fortunately only enough balsa to make one fin is needed, which I think I can get myself.
I plan on mending the Saturn this weekend, and I will then balance it. My only question is, when you say 'Cut the shock cord from the adapter at the screw eye. Then stuff the shock cord back into the tube but leave it bunched up near the top', should I replace the nose cone, or leave it off, and if I do find the distance to be less than 102mm, do I then add nose weight??

I will let you all know when I next fly the Saturn, and hopefully report a successful flight.

Thanks,

Silverfish

(P.S. I found two neighbors with warts, so burnt them both just to be sure. I have also checked for wizards, fairies, sprites, or any other magical creatures, so hopefully I am now in the clear )

Good job burning your neighbors- you can never be too careful.

The weighing you'll be doing is only for the section that is composed of the main T60 tube and all attached items. So the upper section consisting of the adapter, S-IV-B tube and Apollo spacecraft is not included. We'll weigh and balance that section afterward and by itself, then weigh the entire stack. Doing it this way can help pin down any imbalance- I'm just taking you one step at a time. We're using the bottom edge of the T60 tube as a common referance point- it is called the "Datum." If you and I both use the exact same datum point, then I can sit here and correctly compare the balance of your rocket with my own which has known good flying characteristics. If yours is very close to mine, then balance is not likely the issue.

Sorry for taking so long, I was working on my cluster when I noticed the saturn sitting in the corner, and suddenly remembered it was in need of repair.

Anyway, I made another fin and glued it on, and found the balance as you told me. The length from the bottom of the body tube to the balance point is 116 mm (I guess that means that the lower part of the rocket is stable?).

Silverfish

The upper stage should balance out at 77mm forward from the seperation plane of the balsa adapter

Overall, with the shock cord installed the rocket should balance out in the 20.6 cm area measuring forward from the base of the T-60 tube.

The upper stage balances at 69mm (minus the shoulder).
The whole rocket balances at 187mm.

That sounds slightly aft, you should add some weight forward.

Thanks for your help Doc! I drilled a hole in the adapter and poured in enough led shot to bring the CG to the right point, and then soaked them with CA to stop them rattling around.

I got a chance to fly the Saturn today, and it was a successful, if surprising flight . It flew straight as an arrow, hit apogee, just began to arch over, and then the ejection charge went off. It was then that I noticed the body tube falling faster than the nose cone, and one end if the shock cord flapping around... Oops :S. The body tube hit the ground HARD, and I saw the nose cone floating off into the distance. I went to inspect the damage, expecting there to be a large pile of shredded paper waiting for me. I was amazed to find almost no damage at all (one of the fins was hanging off, but a bit of glue and it will be easily fixed)!! The shock cord had failed where the kevlar and elastic cords were tied together, and so I have now used CA to secure the knot.

All credit to Dr Zooch for desiging a brilliant little rocket that flies well with or without a parachute !!

Silverfish

Great to hear that you got it flying. FYI- those fins are designed to break away under exactly that sort of impact. Scrubs off the energy from the impact.