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JumpJet
04-12-2011, 04:56 PM
I just thought you might like to see a new personal project I am working on. I drew the model up over the weekend. I started the build yesterday and this is what I have completed so far. The wing is a solid piece of 3/16”B-C grain sheet balsa. The wing has already been air foiled in the photo showing the parts of the model. The body is constructed out of 1/16” & 3/32” balsa with a couple of hollowed out blocks in the nose. I still have a lot of stuff to do like creating the hatch area and running the pushrods out the rear. Right now the model is held together with tape. I still need to dope and tissue the entire model before moving on to the final assembly. I love long tail-moments on my gliders and as you can see this one clearly shows that.

I haven’t a clue how this model will perform during boost but I am quite certain it will glide very nicely. I will build a couple more until I get her flying the way she needs to.

I am going to use a standard micro radio setup that uses a seperate reciever and servos.


Here are a few specs

Current weight 1.64 oz.
Span 23”
Wing Area 85” Sq Inches
Power B & C motors
Estimated Final Weight 3.2 oz.




John Boren

kevinj
04-12-2011, 09:53 PM
Definitely has that TLAR look about it. I'd give it a go if you have extra parts cut. ;)

kj

BEC
04-13-2011, 12:15 AM
Indeed - that looks nice, John. I'll be interested to see how it goes from here.

Eagle3
04-13-2011, 07:20 AM
Great looking project John! Looking forward to the flight reports.

Buzz

JumpJet
04-13-2011, 01:15 PM
Last night I applied color tissue and Sig Nitrate Dope to give the model some color. Not my best job covering with tissue but I haven't covered anything this big in over thirty years. This covering added .33 ounces of weight. You will notice the Vertical Stab is not on the model at this time. It makes for easier photo taking.


John Boren

ghrocketman
04-13-2011, 01:21 PM
The glider looks great, but I sure would not want to use Nitrate Dope on anything going to be even remotely close to ANY sort of flame, or for ANY rocketry application other than for mixing pyrogen for igniters.
The Germans learned the hard way with their Nitrate-coated hydrogen-filled dirigibles.
Is there a reason why you used this instead of Lite-Coat Butyrate ?
Lite Cote is low-shrink clear butyrate from Sig, and has the benefit of NOT igniting like a tinderbox if one comes within a foot of it with a flame.

JumpJet
04-13-2011, 02:20 PM
I used Nitrate dope since it doesn't shrink and I had in on hand. I used Nitrate Dope on every NARAM 52 contest model I made last year and never had a problem with them catching on fire. . The Myth Busters did a segment on the very issue you mentioned concerning the Hindenburg. There was more to its fast burning destruction then just the Nitrate Dope.

I'll give a flight report when this model is completed. If it does in fact burn up, I certainly won’t use Nitrate Dope Again!


John Boren

FlyBack
04-13-2011, 03:05 PM
There was more to its fast burning destruction then just the Nitrate Dope.... I think the powdered aluminum additive had a role if I recall.

John,

Great looking design! Best of luck with the test flights. Also, have you ever tried adding Borate and Borax (in solution) to water based polyurethane? I understand a very thin wash of that mix on balsa or paper tube makes an excellent fire retardant.

Regards,

FlyBack

JumpJet
04-20-2011, 11:54 PM
I just completed the installation of the radio gear. She came out a lot heavier then I expected but I didn’t try very hard in getting the lightest weight radio either. I still may need to add some nose weight to get it to balance but I won’t know that until I do some test glides, so a lighter radio may not have done much good any way.

The best part about this model is that I had everything laying around the shop so it didn't cost me a penny in new investment.

This is what I ended up using for a radio.

Servos 4.4 gram each
2 Cell Lipo 250 mAh 17 grams
Receiver Hitec Micro 05S 9.4 grams
Speed Control GWS 2Amp 6 grams Used as a BEC

Total model weight so far 3.8 ounces


John Boren

JumpJet
05-04-2011, 06:03 PM
Not much more to report right now on the glider other then I did some test glides with it and I was landing a hundred plus feet away. It appears to glide very well. I had to add some up elevator so I may need to change the incidence of the stab by about a half a degree on the next model. And I’m pretty sure it isn’t nose heavy since she balances around 60% back from the leading edge at the root cord. Assuming it doesn’t crash and burn on the first launch I’ll know what she needs to dial her in gliding wise. My biggest fear is the boost right now but if the weather is good, I’ll know how she flies this weekend.


John Boren

zog139
05-05-2011, 12:34 PM
Servos 4.4 gram each
2 Cell Lipo 250 mAh 17 grams
Receiver Hitec Micro 05S 9.4 grams
Speed Control GWS 2Amp 6 grams Used as a BEC



OK someone help the new guy ! What is the purpose of the Speed Control ? And the reference to "used as a BEC" ?

ghrocketman
05-05-2011, 12:52 PM
BEC can stand for one of two things here:

Bussed Electrical Center
or
Battery Eliminator Circuit

JumpJet
05-05-2011, 01:51 PM
I am using a 2-cell Lipo battery for the radio. The receiver I am using likes to have a working voltage more in the five to six volt range while the Lipo produces over 7.4 volts when fully charge. The speed control with a built in BEC will drop the battery voltage down to a level the receiver can use. You can buy a BEC unit all by itself but since I had this micro speed control laying in my draw I used it instead.


John Boren

JumpJet
05-07-2011, 04:30 PM
I test flew my glider two times today.

The first thing I know I did wrong was to launch the model vertically. I was way too lazy to build a custom launch rail for it but will do this for my next outing. Instead I simply stuck a ¼” Diameter lug on the top of the motor pod and put it on one of our mid power pads.

The second thing I learn is that I probably should have NOT touched the controls on boost, since the model may have been better off.

Thirdly I will most likely need to put tons of expo on the elevator for boost or use a Duel Rate and set it on low. What I really want to happen is for the model to boost hands off but since this project is just for fun I may never spend the needed time to get all the bugs worked out. I do however believe by just switching a custom pad set at a angle the model will most likely boost much better.

On the bright side even though both boost were far from straight up I got a 44 second flight on my first attempt and 57 seconds on the second attempt.


I have uploaded a video to both flights. You can see it at this site.

http://www.johnboren.com/html/c_engine_rocket_glider.html


John Boren

tbzep
05-07-2011, 04:42 PM
The first thing I know I did wrong was to launch the model vertically.

The second thing I learn is that I probably should have NOT touched the controls on boost

Thirdly I will most likely need to put tons of expo on the elevator for boost

After reading the above three events, it sounded like a disaster in the making. It was good news to read the bright side....

On the bright side even though both boost were far from straight up I got a 44 second flight on my first attempt and 57 seconds on the second attempt.

kevinj
05-09-2011, 02:16 PM
Dual rates, or better yet- a flight mode for boost and another one for glide.

From the video it looked like the model pitched up (on it's back) during boost, which to me seems to be an issue with not enough angle on the motor pod, or too much incidnece on the tail.

Unless that was the reaction to a downward pitch? Hard to tell.

One of the things that I've been taught to do with a new RCRG is to get it in the air (tow, catapult or DLG) and then set it in a dive. Trim the dive so the model doesn't try and pull out or tuck it's nose under, and that's your starting boost trim.

Scott and I managed to get our Vapor-brick controlled model to boost almost hands off (needed a little push over at burn out) on A and B motors. I think a C would have been too much for that little glider.

Let us know if you plan on making parts sets available. I'd certainly purchase one.

kj

jeffk813
05-26-2011, 05:39 PM
That's inspiring! I've actually got plans on my bench for an RC BG utilizing this system:

http://www.wingswheelsandrotors.com/ekmps/shops/wwrshop/images/spektrum-ar6400l-dsm2-6-channel-ultra-micro-receiver-spmar6400l--2718-p.jpg

It's a Spektrum AR6400L receiver. 6-channels, two built-in linear servos, ESC (not utilized), measures roughly 1 inch square, and weighs in at 0.14 Oz. For power, it runs on a single-cell LiPo battery that is a quarter the size of the receiver and weighs only 0.15Oz

The only drawback is that it's made for the Spektrum 2.4GHz radio. Not a big deal for me as those are what I use in my RC helis and planes, but a suitable transmitter can be had for about 60 bucks. Less if you do your homework on eBay.

I wonder if one could be made small and light enough for mini motors?

kevinj
05-26-2011, 09:23 PM
Yes Jef. Several folks have made models with the spektrum bricks down to 1/8A.