Big YF-12 RC Rocket glider for G-12 motors

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burkefj

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One day I'll sleep through the night and not wake up at 3am thinking about things like this....YF-12 interceptor version of the A-12/SR-71 family. Rarely modeled and I've never seen one as R/C let alone a rocket glider. This was an interceptor version with missile bay that wound up being used for testing the aim 47 missile and doing high speed/altitude testing for NASA. I believe the only survivor is in the USAF museum in Dayton.

The chines were shorter on this design because of the large rounded nose cone that held the radar system. The R/C Rocket glider uses 9mm depron, bt80 tubing and is designed for 32mm glider G-12 reloads. Currently 18.2 oz with electronics, add, paint, nose weight and motor it'll be about 27 oz ready to fly. 32" wingspan, 59" long. About 1/20 scale. Construction is identical to my smaller 24mm kit version just upscaled by 1.5x which gives me 2.25x wing area and approx same wing loading and flight times

Due to size and shipping cost, no plans for plans or kitting, sorry.

86698906_564741094162538_8472830002277122048_o.jpg
 

cwbullet

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Very nice. Go light with the paint.
 

burkefj

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Testors flat black rattle can which is one of the few paints that doesn't melt the foam covers pretty well one can will usually cover an entire small model and adds about half an ounce of weight, this one's a little bigger so took two cans. I've already budgeted that in my calculations.

Very nice. Go light with the paint.
 
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cwbullet

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True, I was also concerned about added weight.
 

BABAR

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may sound crazy, but I have had good results with a black Magnum Sharpie (sounds like an oxymoron), adds very little weight. You have a lot of surface to cover, however.
 

burkefj

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Yeah, this would be all splotchy, there is no way to cover something this big with a sharpie, the beast is painted, added just under 1 ounce which is exactly spot on. Just waiting for some decals and motors to fly it.

Frank
 

aerostadt

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With all these models I was wondering when you sleep. I guess it is before 3 AM
 

burkefj

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I got some great flights in on a G-25, G-12's and F-25's, all worked great

 
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Crawf56

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Wonderful video work. But I fear you are picking up my bad habits (messing with old motors). o_O
 

BABAR

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I got some 20 year old reloads from George Rachor today, it was an adventure. One package was marked G-12 but were actually F-16's with a fully slotted grain with a large nozzle opening and .062 fiber forward washer. Of the actual G-12's, one burned twice as fast as normal 4 seconds instead of 8, one burned at 9.5 seconds with sub standard thrust, three burned with about 70% thrust as normal for about 12 seconds. The F-16 chuffed and got just barely off the rail after 2 seconds and I was able to save the model by pitching over and holding it 3' off the ground till burnout, and the F-23's would not light at all. I didn't try the second F-16.

In all, the YF-12 handled it great, perfectly trimmed and balanced, with fresh G-12 motors it should be great. Here are the fast burn G-12 and almost nominal G-12 flights.


Here is the blooper reel of yesterdays flights with motors from 1995-96 that did not perform as expected, all were in sealed packages, three G-12s burned for 12 seconds instead of 8 and was very weak(I show one of those flights), and the F-16 chuffed and barely got off the rail, I was able to control it and land it safely with no damage.
nice save!
 

burkefj

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Originally I was hoping when I pulled back it would just settle flat and slowly burn out while sitting, it went into the smoke for a second, then I saw it balloon back up, so I stuck with it and after a couple seconds it quit and settled on the grass, no issue.

nice save!
 

BABAR

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Great flights and camera work (as usual;))
 

Weldo

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Another very cool build! I've always maintained that the SR-71 and it's kin were among the most amazing machines ever made my man! The things these planes were capable of is just mind boggling and your model does them justice!

In your first video, it seemed like the last motor had a strange liftoff, it was around 5:30 in the vid. It looked like it lifted slightly then really took off. Was that a different motor from the others or some kind of anomaly?
 

burkefj

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That was a 20 year old reload anomoly, i sent the vid to aerotech, Karl thinks shrinkage away from the casting tube allowed burning along the outside of the propellent, not just the end causing a double fast burn time after the initial ignition, I was fortunate the model was built strong.

Another very cool build! I've always maintained that the SR-71 and it's kin were among the most amazing machines ever made my man! The things these planes were capable of is just mind boggling and your model does them justice!

In your first video, it seemed like the last motor had a strange liftoff, it was around 5:30 in the vid. It looked like it lifted slightly then really took off. Was that a different motor from the others or some kind of anomaly?
 

Weldo

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Oh, I see. Thanks for the info!

Hey I wanted to ask you, what's a good way to get started in these kind of flights? Like a decent starter controller unit and a smaller, lower flying kit? I've done a rocket glider a time or two but not one that had any sort of control.

When looking for a controller is there a minimum requirement like number of channels and things like that?
 

burkefj

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The way I do them, which is to launch slightly tail heavy and then glide nose heavy without having to dump balast it requires a launch and glide elevator trim setting to be different. Most 2-5 channel radios don't have this ability of mixing to a switch, you can do it with trims but it's clunky to do while trying to control the model. Usually 6 channel and up have a flap setting which also includes putting a different elevator setting based on the switch position, I usually use this switch/setting to set my boost and glide, then I'm just steering after that is set right. The second thing you need for my models is elevon mixing which mixes roll and pitch to the two servos, also a function on 5 ch and up radios typically. On my website, dynasoarrocketry.com if you go under general instructions I have links to what I use for reference you can refer to, there are cheaper but I have not personally used them. My kits I make are fairly large, 38" long or so and fly to between 400-500 feet on average if you go straight up, a bit lower if you angle slightly, which isn't really that high, you can still see them well enough and it gives you enough glide time to get used to it. You really need to be comfortable with flying a fairly quick RC airplane first before you try a rocket glider because you can't shut off the motor if you get into trouble. There are lots of good beginner ready to fly planes out there, the radian is a good one.

Oh, I see. Thanks for the info!

Hey I wanted to ask you, what's a good way to get started in these kind of flights? Like a decent starter controller unit and a smaller, lower flying kit? I've done a rocket glider a time or two but not one that had any sort of control.

When looking for a controller is there a minimum requirement like number of channels and things like that?
 

Weldo

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This is neat stuff. I did some reading and have another question or two.

Are you using any controls under boost, or is it hands off and it goes where it goes?

Also would the flight of an elevon model be successful WITHOUT the roll/pitch mixing ability?
 

burkefj

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Yes, you are flying the model at all times, the only models that are true rocket gliders that are hands off(that don't eject balast or a booster) are never hands off really. Not major adjustments, but there is never no wind.

There is no elevon without mixing, not sure what you are asking, if you are asking if you could fly it with just elevator control, then no, you need to steer not just adjust pitch.

A good radio will last you for 20 years or more, get the best you can, not the cheapest.

Frank


This is neat stuff. I did some reading and have another question or two.

Are you using any controls under boost, or is it hands off and it goes where it goes?

Also would the flight of an elevon model be successful WITHOUT the roll/pitch mixing ability?
 

Weldo

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Thanks again! Sorry if I wasn't clear but I was wondering if a flight could work on just two channels. Something like channel one has an elevon setting for boost and an elevon setting for glide. Then channel two was simply roll adjustment for the glide stage. But I see now that flight with an elevon design would be impossible without elevon mixing.

I've flown the Apogee SR-72 Darkbird and since it has no control, the elevons simply have a boost setting and a glide setting. What I was wondering was within that glide setting could the elevons be manipulated independently to get control of roll.

So at apogee, channel one kicks the elevons into glide setting, which points the elevons upward toward the sky. Then channel two would allow the controlled lowering of one elevon at a time to influence roll.

After thinking about it I don't expect it'll work. The servos would be fighting against each other I think. And at best the control would be crude.

Sorry if I'm rambling or spouting nonsense but this was kind of a mental exercise for me! Rocket gliders are a cool way to add something more dynamic to the rocketry hobby.
 

burkefj

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For some reason I deleted my post, copying here again for some motor issues with the G-12's

I got some reloads from George Rachor in Feb, it was an adventure. One package was marked G-12 but were actually F-16's with a fully slotted grain with a large nozzle opening and .062 fiber forward washer. Of the actual G-12's, one burned twice as fast as normal 4 seconds instead of 8, one burned at 9.5 seconds with sub standard thrust, three burned with about 70% thrust as normal for about 12 seconds. I did not get the date codes on these.
 

burkefj

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Now that my G-12 casing got destroyed in a cato, I'm now actually preferring flying this on F-25, G-38 and G-40 motors. G-38 and G-40 give similar flight times to the G-12 and are a bit more "exciting" to pilot and watch as an observer:) They are readily available and don't require an expensive casing either. Aerotech has submitted the new 29mm G-12 single use for certification which would require a bit more nose weight but in sims, even given the longer burn time it doesn't look like it goes any higher at this weight.
 

tab28682

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I love the G40 in a large RC RG. I have a ton of G40 flights on the HobbyLab F-14 prototype back in the 1990s. It was about 32oz off the pad and was a great flyer under boost.
 

burkefj

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Nice, this model is at 28.4 oz rtf with G-40 and 1/2 ounce 29mm-32mm adapter, It flies really nicely on the g40s like you said.

I love the G40 in a large RC RG. I have a ton of G40 flights on the HobbyLab F-14 prototype back in the 1990s. It was about 32oz off the pad and was a great flyer under boost.
 
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Brian V

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That is very nice model you there Frank!! Can’t wait till I get my kit version!!
 
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