L2 for the Frog

Well, here goes nuttin! For starters, here's a .jpg of the Rocksim file. This is a pretty rough draft as I don't have shockcord weights and the like in the design yet.

I chamfered the inner angle of the aft fins (only by about 1/4", but that should make a pretty significant impact) to avoid creating too much of a stress point there.

Okay, this is gonna bore the snot out of everyone, but here's my first body tube I glassed...it's the 4" section that will house the avionics bay.

Please forgive the photo quality. I am using an old Polaroid PDC640 digital camera and it sucks.

Nope. No server space, so they're all going up here. Here's a shot of 2 centering rings being glazed, 2 more being epoxied together, and the bulkheads on the alt bay being glazed. The alt bay is the Binder Design model. It's very simple and straightforward.

Oh, yeah. The CRs are Masonite from Binder Design as well. After glazing them, they're quite strong. I will be putting a single CR at the front end of the MMT, then a doubled up one at the front of the fins and another doubled up one at the rear of the fins. The fins will also be secured with 2 part foam along with interior fillets and tip-to-tip glass on the outside.

Bored yet?

Here's the mandrel/stand I'm using to glass the tubes. Idea courtesy of Carl the Tulanko. Pardon the mess.

Very cool design Kermie! What motor are you planning on flying this sucker with?

Depends on what it ends up weighing out at and what wind conditions are. I'm hoping to use a K550 as it might just be the last HPR motor I get to fly.

Kermie...it is looking great so far bro...keep the pics coming!!!

Carl

yes! please keep the pix coming! (if i hear even ONE person knock the pix after hearing darned near EVERYone beg for pix, so help me.... )

I may know a lot about my end of the rocketry spectrum, but I have never glassed a tube and have never used anything above a G motor. While I may not contribute much to these discussions, i AM reading them and (like it or not), I am learning also...

jim
(the lifetime student of rocketry)

Jim, if you ever feel you have a suggestion or thought for this rocket, please chime in. I don't know a whole lot about any of this, so each project I've done, I've made an effort to do something I haven't done before. This one's got a bucketfull of firsts for me, from glassing tubes to dual deployment to 2 part foam. I've already leaned on Carl, Dick, Phil, and Mark for advice and I'm open to hearing it regardless of your experience with HPR or lack thereof.

It's still all the same. Build it as strong as you can with what you have to work with. Make sure the CG is in front of the CP and the chute is big enough to keep the damage to a minimum and protect the chute from the ejection. Oh, yeah. And if you're gonna let Carl see it.......sand and prime...sand and prime...sand and prime...sand...zzzzzzzz.

Coming along nicely

No server space you say?

Well, after you lead all of us through your L2 journey, then let's put together a nice package (page) for EMRR to add to the other L2 projects.

I love the design of your fins. Did I miss the material you are going to use for them? There are always concerns with fins swept forward that way. People worry about flutter, so depending on thickness.....

- Nick

Fins are going to be 1/4" ply with tip-to-tip glassing. I'm hoping that the chamfer mentioned in the first post will do a little bit to reduce flutter. Having a sharp angle there (which is what I've usually seen with forward swept wings) really creates a weak spot that would be prone to allowing flutter.

Once it's all done, I'll be happy to write something up for EMRR. I was all set to do so for the Binder Design avionics bay when I noticed that someone already beat me to it.

Nice work K. I can't wait to see her fly...

For glassing tubes consider this idea.

Take two lengths of 1 x 4 about 8 inches long and attach them to both ends of your work bench. Buy a suitable length of 1/2 inch thin wall conduit and suspend it the length of your workbench using the 1x4s for support. You can drill holes in the 1x4s and slide the conduit through them at a convenient heighth (I got lazy and just notched the tops. Then make a couple centering rings out of cardboard and put a 1/2 inch hole in the center of them. Insert the crs into the tube, slide the conduit through them and suspend the whole deal over your bench. I don't recall where I saw this idea but it works great. You can sit while you glass and you can turn the tube by turning the conduit. Just a thought.

Very good idea and I did consider something similar. I went this route, however, because with the end pieces, I also have 2' sections (the sections on the end in the pic are 1'). With the 2' sections, the whole contraption becomes a fairly portable rocket stand to take to launches.

That and I'm sucking up to Carl since he's the one who volunteered to sign off on my L2.

I started out planning on epoxying the shock cord to the side of the MMT as I've seen so many people do on here. Then in an incredible lack of foresight (this is what I mean by making stuff Kermieproof), I just went right ahead and epoxied the front CR to the MMT. DOH!

Anyway, the more I thought of this, the more I was glad I did it. My MMT is 17" long, and if all goes well with the regs, I might want to end up flying something slightly longer in it. This, of course, over the long run, could be hazardous to your tubular nylon.

Anyway, my answer was to drill a hole in the front CR and put an eyebolt in there. I had picked up some JB Weld just out of curiosity (and to use with the motor retainer) and I used it to attach the eyebolt. Love this stuff! I actually ended up completely covering the nut with the JB Weld partway up onto the thread of the screw. I also put a fillet all the way around the eye part of the screw as well. I don't think it's going anywhere.

Ohya...by the way....I just won an auction on Ebay for an Olympus D520...125 bucks inculding shipping! Pic quality should improve shortly.

Carl stongly recommended a Sky Angle 52" chute and a 24" drogue based on an estimated 10 lb. dry weight for this design. I thoroughly respect this recommendation and the SA chutes look awesome. They are, however, a little pricey.

I have had a couple of thoughts on this. I see the 63" mil spec parachutes on ROL auctions from what looks like Aerocon. Are these an acceptable substitute?

Also, for the drogue, from what I've been able to discern, it appears that a 30" X-form chute should be about the equivalent of a 24" round drogue. Also, I've gotten the impression that X-forms minimize drift (this IS a consideration if what they tell me about average wind conditions is correct). Are these assumptions correct? If so, are there any particular challenges to packing an X-form chute? Also, would an appropriately sized X-form chute be a good choice for a main?

Have I asked enough stupid questions for one post?

Kerm...

I thouroughly understand the budget thing bro! An X-form for a drogue would be fine ... you would have to do the math on the 63", but since you are doing dual deploy, letting it come down nice and easy,especially for an L2 cert, is a good idea. I think the 63" would work fine size wise, just haven't calced it yet.

Carl

Have you (or anyone) used an X-form chute? Does it actually reduce drift for the same descent rate?

As a drogue, the Xform isn't going to do much for drift, since you are falling fast from 50-120fps...as a main, I couldn't say...never used them for a main.

Carl

Kermie,

I've standardized on X-forms for all of my parachutes 18" and above.

First let me say that there is a lot of debate on whether or not they reduce drift. Theoretically, any type of chute falling in a cross wind should drift sideways at the same speed as the wind. If two chutes had identical descent rates than each of them should drift just as far as the other.

In my experience, however, X-forms seem to drift significantly less than flat chutes. Last year at NYPower for example my rockets were landing in front of the parking area while many using flat chutes were landing in the parking area itself.

I also like X-forms for two other reasons. First they pack very easily and rolling the shroud lines around them during packing tends to unroll them like snapping a sheet in the air when making a bed. I've never had an X-form tangle or fail to open if it was fully ejected from the rocket. Second they seem to open "gently". Again, since I've switched to X-forms I've never had a zipper due to a hard deployment.

Ken Holloway, NAR #78336, L-1

My opinion of X-Forms is pretty high as well. But for slightly different reasons. They don't spin as bad as regular chutes. And I hate untwirling TN

Alan

I just thought of another good selling point for an X-form: visibility. Strikes me that an 80" X is going to be easier to see than a 65" circle. Could be wrong on that though, too. On the other hand, that Sky Angle with only 3 shroud lines looks pretty Kermieproof (and the swivel that comes with 'em should minimize the TN twirling too).

Anyway, glassed my first "real" tube tonight, layer 1 (Carl, I'm sorry...I know you said I'd only need one layer, but I'm the paranoid type so I'm goin' 2 layers of 6" glass) of 2. It was a bit different than doing the little 4" section. I just went down to check on it 2 hours after I finished and I'm glad I did. There were no pools on the tube when I finished, but in sitting on the spindle, the epoxy had flowed down, creating pools on the lower area of the tube. Had I not checked, I'd have had a truly joyous (sic) sanding session ahead of me. As it was, I was able to dab it up with paper toweling. New digital camera should arrive tomorrow, so I'll wait and post a pic testing the new camera out.

Here's the pic. Pardon the size. My current editing software sucks, and the Paint Shop Pro I'd been using suddenly went psycho on me and wrecks any pic I try to put through it.

this rocket is going to look so kool when it's finished what you launching it on and show us some launch pics mean as man

I'm planning (hoping) on a K550 launch.

I finally finished glassing both tubes. I'll be placing an order with Ross tomorrow for the MAWD, a couple of LOC couplers (gonna double wall the alt bay), and some Nomex for the chutes and shock cords. I decided to hold off on buying the chutes until I head down for Whitakers. I can swing by Magnum down there, save on the shipping, and then I'll know what everything will weigh for sure.

Right now, I'm waiting on the @(#$& clowns at Hobbytown USA to get my 1/4" ply in. I went in a week ago Sunday to order and last Sunday they hadn't even put the order in to the distributor!

I'll post pics as soon as there's something worth posting.

Kermie...
I picked up a 12"x12" nomex blanket for my V2 but, won't be doing that one for quite a spell. If it's the right size for ya, let me know and your welcome to use it.

12 x 12 is perfect!

Let's see...Carl's motor case, Stones' Nomex blanket...I got an offer for a chute I could use...practically a group project already!


I'm thinking Phil should bring a cow decal.

What gauge wire would everyone suggest for wiring the electronics? I have a bunch of CAT-5 wire I use for ignitors that's 24 ga. Is that about right or do I want something heavier?

I've used the old leads off of daveyfires for wiring my electronics, and that seems to work fine. If you are doing runs longer than 6 or 7 feet, then I might switch up to 20 or 18 ga wires. IIRC, daveyfire wire (hey that rhymes) is 22 ga solid.

HTH.