RC Cosmos Mariner

[kevinj]

I did some more work on my RC CM yesterday. Originally had decided to make it BG with the internals from the kit, but due to poor parts fit (the front CR and weights barely fit into the BT-55 tube) I'm moving on to an RG.

Progress so far (photos coming later):
Built all the balsa parts.
Cut out the sub fin to allow full movement of both evelvons.
Made new motor mount (sized to accept E9-P motors).
Cut new BT-55 tube to hold motor mount.
Covered exposed balsa with trim monokote.
Sourced the RC gear and mocked up servo placement (in hanily provided molded trays in the bottom half of the body shell).

Things to work on:
Control linkages.
Hinges.
Assembly and paint.

kj

[foose4string]

Interesting idea. Someone flew one of these at NARAM and it had a great looking free flight recovery. Of course, we've all heard of the poor flight reports as well. I look forward to seeing this one.

[CaninoBD]

Interesting idea. Someone flew one of these at NARAM and it had a great looking free flight recovery. Of course, we've all heard of the poor flight reports as well. I look forward to seeing this one.

That would be me, I flew it at NARAM 48 in SFFS. It did glide rather nicely. I flew it twice, I DQ the first flight because the parachute got caught on the pod hood and the pod streamed line in. There was a little stall in the first glide. Made a adjustment to the chute lines and add a little nose weight the next flight was qualified and the glide was very nice. Much better then you would think something that heavy could glide.

What R/C gear are you using?

You can see pictures of my CM on the NARAM Live site. Chris got a couple of nice shots of it.

NARAM Live 2006 (http://www.naramlive.com/naramlive-2006/naramlive/08friday/03.html)

http://www.naramlive.com/naramlive-2006/naramlive/08friday/day/DSCN0558.JPG http://www.naramlive.com/naramlive-2006/naramlive/08friday/day/DSCN0559.JPG

[rokitflite]

That would be me, I flew it at NARAM 48 in SFFS. It did glide rather nicely. I flew it twice, I DQ the first flight because the parachute got caught on the pod hood and the pod streamed line in. There was a little stall in the first glide. Made a adjustment to the chute lines and add a little nose weight the next flight was qualified and the glide was very nice. Much better then you would think something that heavy could glide.



It was at NARAM 50 that Foose and I saw the good flight of which he speaks... As I recall (probably incorrectly) the model was unpainted. I looked up because the ejection charge sounded like a shotgun blast :eek:

[CaninoBD]

It was at NARAM 50 that Foose and I saw the good flight of which he speaks... As I recall (probably incorrectly) the model was unpainted. I looked up because the ejection charge sounded like a shotgun blast :eek:

O, I stand ( actually sit ) corrected. In either case, they can be made to glide nice.
A R/C version would be cool.

[kevinj]

What R/C gear are you using?


Nothing fancy. I usually keep a bunch of cheap small servos around. I got a few of these:

http://www.rc-dymond.com/index3.php?productID=1436

when they were on sale. Will probably use one of my Berg recievers and a small 200mah battery.

kj

[Bill]

In either case, they can be made to glide nice.


Anybody want to share some tips on how to make this kit glide better?

Whenever I see on in the bag, it looks more like a model boat than a rocket.


Bill

[CaninoBD]

Anybody want to share some tips on how to make this kit glide better?

Whenever I see on in the bag, it looks more like a model boat than a rocket.


Bill

You are not going to win any duration events with this, but it can be made to glide well for its size and weight. Also, this shouldn't be your first glider. Try a Quest Flat Cat or something like that first.

If you follow the steps 13 & 14 in the instructions, that really all you need. One other thing is run a string through the launch lug and make sure the model balances side to side.

Find some tall grass to do your test glides over. Try to do your test glides when there is little or no wind. Make sure your throw is even and don't try to over throw it.

This is what I did. After the first flight, it did notice it had a slight stall in flight, so I added a little more nose weight. The second flight was fine.

Trimming gliders is a art and you will get better with practice.

[kevinj]

Photos-

The balsa skeleton with new tube/motor mount and the monokoted wings.

Preliminary gear layout.

Top shell on.

kj

[Bill]

The instructions call for a silicone glue for attaching the vacuformed plastic hulls to the wing. Any particular brand work better than others?

Would something like Weldbond work? The label mentions many non-porous materials, but not plastic; perhaps because there are so many different kinds.


Bill

[CaninoBD]

The instructions call for a silicone glue for attaching the vacuformed plastic hulls to the wing. Any particular brand work better than others?

Would something like Weldbond work? The label mentions many non-porous materials, but not plastic; perhaps because there are so many different kinds.


Bill

I used GE Silicone II. This stuff is almost imposable to sand, so you need to get everything right before it dries.

I have seen where others said they used contact cement, but I can't comment if that is any easier or not.

[kevinj]

Today I covered the main fins in monokote trim and glued them to the wings.
I also trimmed the elevons so taht they would move freely, and beveled the leading edge to prep for covering them and making the hinges.

Tommorrow I'm going to get another sheet of trim monokote and plan to cover and attach the elevons, and the sub fins.

kj

[kevinj]

I've been bad at taking photos, but I've been slightly busy on the RCCM.

I decided to move the servos forward and centered on the balsa so that the pushrods stay inside the sheel and pass on either side of the BT-55 tube that holds the motor mount. I created some torque rods to connect the elevons to the push rods. I attached the elevons and glued in the fins. I promise to take a photo of all that bfore I attach the body shell.

I'm going to cut a hatch in order to have access to the rx and battery. Was toying with the idea of going in through the weight compartment, but things looked a little tight for that.

Will most likely start painting this weekend.

kj

[kevinj]

After being frustrated byt he control linkages, I had a breakthrough today with a suggestion by Rokitflite and now the glider is almost ready to go. Final balancing and maybe a quick trimming throw or two and we may have a flight tomorrow. Either way photos have been taken, and I'll post them "real soon now."

kj

[foose4string]

Kevin's Mariner turned in some impressive flights today. The radio lost signal during it's last flight which spelled bad news, but Kevin had it trimmed very nicely.

[kevinj]

Great photos Foose. I'll try and get the video up tonight.

kj

[Leo]

Great pictures :)

[rokitflite]

It was a great model, that flew great and was flown great... It met an untimely demise and if it is not rebuilt I will not be talking to Kevin again :mad: .

[FlyBack]

...It met an untimely demise ...

What happened? It is/was a great looking model.

FlyBack

[kevinj]

Here is the video of the 1st flight on a D11, with some footage of the controls at the end.

http://www.youtube.com/watch?v=bKyEl6pQ2Ds

I made 2 D11-P flights and then stepped up to E9-P's. The controls were responsive, and the model wanted to pull up in boost, so for the 1st 3 flights I let it do that.

For the 2nd E9 flight I held in right stick to make it boost like the regular version (spiral rolls) and that worked out ok. Got a lot of altitude and made a couple of circuits of the launch area.

For the 3rd E9 flight (and the last) I did the same thing, held the stick over for boost. The glider transitioned, and I was able to start controlling it. The model then stopped responding to control input and started a spiral dive into the ground. It wasn't pretty. :(

Best guess is that as the model was heading away I may have been pointing the transmitter antenna directly at the model (my antenna doesn't bend due to it having been dropped the day before and breaking the pivot). which might have caused a loss of signal.


kj

[kevinj]

An update on the demise of the RC CM. I scavanged the servos out of the model and was using one of them in another project to test the channel assignment on the receiver. When I plugged it in it seemed to work fine, but then started moving full motion from end to end and then stalled with the horn way over. If this happened while the CM was flying, it would have caused the spiral dive that I couldn't recover from.

So main suspect in the crash is now the bad servo and not a loss of signal or other radio glitch.

kj

[FlyBack]

So main suspect in the crash is now the bad servo ...

kj


Kevin,

What brand of servo? Oh... by the way, nice airshow! That really was a nice looking model.

Regards,

DJ Miller

[CaninoBD]

Kevin,

What brand of servo? Oh... by the way, nice airshow! That really was a nice looking model.

Regards,

DJ Miller

Kevin mention that in in post #6, they are D 4.4 Sky Arrow 4.4 g Micro Servos

[FlyBack]

OOOPS!... missed that, sorry. Thanks for the pointer.

DJ

[kevinj]

Now that I know it CAN be done, I do have another kit and am thinking of ways to improve for version 2.0. I had some plans to try and have it done for NARAM, but I don't think that's going to happen. This seems like a fall sort of project.

kj

[kevinj]

Here are the photos I took of the final RC setup I decided on.

kj

[FlyBack]

kj

Very clean setup! What size carbon rod did you use for the pushrods?

One small suggestion for v2.0. Consider using Dymond D47 servos. They are the best sub-5gram servo available and would only add 2-3 grams to your model. (I can add that much with a bad paint job. :o )

Looking forward to seeing v2.0 fly. Good luck.

Regards,

FlyBack