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burkefj
01-12-2016, 12:41 AM
Here's one I just finished, based on my profile foam version, uses bt-80 lightweight tubing and BT-60 ramjet pods. 6mm drpon wing and tail surfaces. Built as light as I can while till having it land on the ramjets and not eject anything in flight. 16.7 oz rtf with an Aerotech E-12 RC or an Estes E-12-0. Wing loading is heavy for my models at 12 oz/sq foot, so glide is not steep but very managable. In over 20 flights so far, no damage landing on the ramjets.

2.6" diameter, 46" long, 21" wingspan.

Frank

Here are a couple of flight videos:


https://www.youtube.com/watch?v=_OPaA993hcM

shrox
01-12-2016, 12:59 AM
Very nice!

tbzep
01-12-2016, 08:07 AM
uses bt-80 lightweight tubing
WHen you say "lightweight" do you mean standard Estes spec BT-80 relative to HPR heavy wall 2.6" tubing, or do you have a source of 2.6" tube that is lighter than standard BT-80?

BTW, your models look great!


.

burkefj
01-12-2016, 09:17 AM
Yes, relative to heavy wall, this is white .021 thickness bt-80 from BMS.

WHen you say "lightweight" do you mean standard Estes spec BT-80 relative to HPR heavy wall 2.6" tubing, or do you have a source of 2.6" tube that is lighter than standard BT-80?

BTW, your models look great!


.

AstronMike
01-12-2016, 10:14 AM
I've done tons of BT-80 based gliders over the last 30+ years, Bomarcs being done a lot since they are 'easy' and tend to be consistent flyers.

Regular 'Estes' type BT-80 is plenty strong for such gliders, and necessary if you are trying to save weight to fly on a given BP motor. Of course, mine are non-RC, with ejecting pod ala Citation style. I've found that, besides upscaling all the 'flats' on a 2.6" Bomarc, I like to 'dork' the overall length so as to use a single 34" long BT.

I then either use a PNC-80K (which is darned hard to obtain), or even better weightwise, just roll a paper cone! Yes, paper, not even cardstock, this saves a bit o'weight, and allows you to glue the main wing on a bit further *aft* to hit a good glide CG point. Obviously, the further aft you can locate the main wing, the less pod ballast you'll need for boost.

With RC, though, the tables are likely turned. You may need the wing either 'correct' or a bit forward, depending upon where you locate your gear and weight thereof.

For the 'n00bz' here reading this, you can search this Forum for 'Bomarc LV' posts, which shows and explains my renditions in further detail. Even if you build one barebones, sans ramjets and a paper cone, you'd find this to be a heck of a sport flyer, even on E9's if you watch your weight. To further add here, I use the Adams Readiboard for the flats, obtainable through Dollar Tree type places. Please get straight unwarpy sheets if you do....

burkefj
01-12-2016, 10:44 AM
Thanks Mike. I actually used a 37" long starting point for the tubing and used a coupler. This gave me two things, it allowed me to get access to mount the rail button mid point easily with a flange head t nut, and also allowed me to put the coupler right where my carbon fiber rods go through to attach the ramjet pods which gives them a bit more robustness for landing. It turned out if I placed my receiver/battery in the nose with the long pnc from apogee components I only needed 1/4 ounce of nose weight so it worked out well. If I had made it shorter I would have needed more weight. My wing is slightly more rearward than scale for an A model, but I think it captures the look well enough.

On my other model the Shuttle concept I just used a single 34" long tube because that was easy and I didn't need any support in the middle.

Frank

tbzep
01-12-2016, 06:55 PM
Are all your surfaces active...wing tip ailerons, elevator, rudder?

burkefj
01-12-2016, 08:48 PM
No, just the elevator surfaces move, one servo on each, mixed to provide roll/pitch control.

Frank


Are all your surfaces active...wing tip ailerons, elevator, rudder?

ghrocketman
01-13-2016, 01:18 AM
Just Elevon control ?
No Rudder control ?

burkefj
01-13-2016, 01:27 AM
Correct, rudder is not needed, in fact none of my 40 parkjets and rocket gliders have rudders, unless you are doing specific aerobatics or taking off from a runway you don't really need it, even when landing in a crosswind I don't have an issue.

ghrocketman
01-13-2016, 04:31 PM
I don't fly a lot of R/C gliders but a lot of powered Pattern, Pylon, and Scale.
Can't imagine doing those without Rudder control.

burkefj
01-13-2016, 05:00 PM
It's just sport flying, so yank and bank works fine. Again, I'm able to hit a runway centerline no problem even in wind, and most flyers at a launch are trying to hit somewhere on a grass field, so pinpoint isn't critical. It avoids another servo/linkage in the aft end which is death to a rocket glider.

You can always add one and corresponding nose weight...

Frank.

I don't fly a lot of R/C gliders but a lot of powered Pattern, Pylon, and Scale.
Can't imagine doing those without Rudder control.

burkefj
06-17-2016, 12:07 PM
Here are some recent flights on aerotech E-12 rc motors and one flight on an old E-15 that was designed for the hobbylab SR-71

https://www.youtube.com/watch?v=W57XVpWSalg

https://www.youtube.com/watch?v=orFdH6xyaJM