Monday, November 23, 2015

The ekranoplan is crawling along


After recovering from a URTI (which also kept me off the field this past weekend), I have resumed work on the Chesapeake Sea Monster. The photo shows one of the transitions that I have been talking about. I made these from a white styrofoam cone from Hobby Lobby. I really hate that rough craft stuff, but it seemed to be the path of least resistance. I cut the end to a bit over the diameter of the tube. I then marked the thickness of the spar and cut the sides off. Once installed, I sanded the transition flat with the tube and began applying with wood filler. It will take three coats. I'll then apply a swab of white glue, which will hopefully protect the foam from the primer. In my experience, this works OK if you use multiple light coats. If any of the foam gets eroded, those areas can be refilled. There will not be any close up photos of the final result!

Random notes/comments about the photo:

  • You can see the rear launch lug. The stand-off was required to clear the forward motor mount plate and the cockpit. Looks like I need a bigger fillet.
  • I am keeping spent motors in the canted mounts since the bottom one is often supporting the weight of rocket and the all seem to get bumped. This is not as big an issue after the rocket got long enough to fit on my rocket rack.
  • The photo in the background isn't the one mine is patterned after, although it did lead to some design mods. The Chesapeake Sea Monster isn't exactly scale.

Tuesday, November 17, 2015

CP, CG and Thrust/Weight, oh my

I have made no building process but I did put in a 'chute and did another quick look at weight and CG issues.

The weight as it stands is 23oz w/o motors. This is three ounces over my rough guess and will still grow a bit. With a 'full load' (i.e. including rear mounted D12's), I am still clearly doing fine. Since I'm not sure about using the rear mounts, I took a look at the thrust/weight for just three D's and eight C's. Those will add about 11 oz and are the equivalent of a 121G65. At 34oz, I should also be fine. I think even with the few missing components it should be OK. The wildcard is whether I need a lot of nose weight.

Unloaded, the CG is about an inch behind the leading edge of the main wings. I don't have enough spent 18mm motors but suspect, if I look both at the completely empty and fully loaded cases, I should be OK. I will have to swing this bad boy at some point but think the current position may not be too far off. Most winged rockets that I have built require the CG hovering around the leading edge of the main wings, mas-o-menos. Of course, this ain't your daddy's winged rocket.

The main problem may be those rear mounted D12's. They are a long way from the current CG and further than the tip of the nose cone. For now I'll keep building and will look back at the 'full load' values.

Monday, November 16, 2015

Chesapeake Sea Monster, a few steps closer!


Here is one view of the Chesapeake Sea Monster (more on Flickr). Tail is dry fit. No transitions on the tail or upper launch lug.  I am deciding on whether she will be gray, as seen on the cone, or white. Decisions, decisions.

Friday, November 13, 2015

Chesapeake Sea Monster update


The Avery full sized labels came today and I have started slapping them on. In this photo, the tail section is just dry-fit. In fact, the tail-mounted 24mm mount wasn't on the flip side at the time the photo was taken. So, let's see what's left other than sanding, filling, filleting, and paint.

  • Paper and attach the rear fin set.
  • Paper and attach the tips on the main fins.
  • Attach the tail section permanently. I may shorten it just a tad.
  • Attach transitions to the tail section.
  • Front launch lug.
  • More shock tether.
  • Final balance and nose weight, as required.
  • Prep motors and igniters.
With the eight forward motors, three main motors and a 'chute, the CG is about half way between the forward mounts and the leading edge of the fins. Not too bad!

Thursday, November 12, 2015

Chesapeake Sea Monster good news, bad news and progress...and kudos to Hobbylinc

First the bad news. It appears our USPS carrier is not delivering packages after dark. After the first missed delivery, the status on their page was something like "undeliverable...we will attempt to return to sender." Today, it was also not delivered, however, my wife ran the carrier down and made him cough it up. He is a sub since our regular guy just had surgery. Which means extra duty and a near guarantee that our mail will be delivered after dark at least for a while. Plus, I will remember that 'return to sender' doesn't necessarily mean 'return to sender.'

The good news is obviously that I have the motors for the Chesapeake Sea Monster. I still won't have it ready for next week's launch. That's really not good or bad, it is what it is.

Now, a shout-out to Hobbylinc.  Their shipment was filled in a timely manner and were very responsive to my panic. I believed the USPS status literally and quickly contacted them to report the package was being returned. They responded quickly and said they suspected that the USPS had it and would try again. They told me not to worry, I would get my order one way or the other. Luckily, it didn't have to be 'the other.'

The latest status:


Here is the upper body with the main wings and forward motor mounts attached. I added some ginormous Superfil fillets to the main wings and I don't think they are going anywhere. It needs a little more filling and sanding. The lower of the two wings looks angled but it is just trick photography.

Wednesday, November 11, 2015

"What, Me worry?"

What Me Worry! #LetsGoMets

"Your item was undeliverable as addressed at 7:54 pm on November 10, 2015. It is being returned if appropriate information is available."

YIKES! that can't be good. Unfortunately, USPS is closed today so my motors are probably on the way back to Hobbylinc.  Lord knows how long it will take to resolve this. It is looking even more like the Chesapeake Sea Monster won't fly this month.

Then, I find my unfriendly local Office Depot didn't have full page labels in small quantity (ie 25 sheets). They also weren't for Inkjet printers. Plus, they were about FIVE TIMES as expensive as you can get from Avery via Amazon. Labels are on order. Balsa prep to restart this weekend.

In a rare moment of optimism, I realized that won't worry any more about how this will fly...I'm have so much fun building it that a successful flight will just be icing on my rocket cake! "What, me Worry?"

Ekranoplan, slow but steady progress


I think I have all the wood cutting done. Here is the tail spar, the giant tail fin that is typical for the ekranoplans, one of the main wings (the other is being glued on at the moment), a triangular piece (which is not typical but which will be attached below the spar, maybe with some trimming) and the main wing tips. The vertical stabilizer didn't make it into the photo. Still haven't decided on a lug or acquired the sticker stock for papering the balsa.

Monday, November 09, 2015

Need to scrounge a launch lug and get some more stickers...

Daddyisbar again shared his experience and convinced me to use a 3/8" or 1/2" launch lug on the Chesapeake Sea Monster.  I wonder what would be a good source for a ~6'-7" lug? Repurposed material of course. I haven't used a big lug in years - the lack of rail buttons has me all discombobulated.

Plus...I'm out of sticker stock for papering the fins!

I started this thinking it wouldn't be ready for this month's launch, which meant it might not fly until spring. Then I started making progress, got hopeful, and ordered motors. Now I'm pretty sure it won't be ready in two weeks. November is getting busy. I guess it will be what it will be.