Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > Rocket Boosted Gliders
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 05-02-2017, 07:32 AM
blackshire's Avatar
blackshire blackshire is offline
Master Modeler
 
Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 5,531
Default *Scale* F9/FH B/G

Hello All,

SpaceX is now employing a model rocket boost-glider configuration to reduce the amount of rocket propellant that must be kept in reserve for the boost-back, re-entry, and landing engine burns of their Falcon 9 first stages (the two boosters of their "triple-barreled" Falcon Heavy launch vehicle will also utilize it). This method--which could also be adapted for use in flying scale Falcon 9 and Falcon Heavy models (at various levels of scale realism and sophistication, depending on the model size and the budget & ambition of the builder)--works as follows:

There is a type of low-L/D boost-glider (B/G), called a tail-slider (see: http://web.archive.org/web/20071015...ealway/srrg.htm ), which consists of a long-bodied but otherwise ordinary model rocket that uses a recovery streamer. Because of its high fineness ratio (its length/diameter ratio, which is similar to that of "Superrocs" such as the Estes Cobra 1500 and Mean Machine) and the aerodynamic effects of its tail fins and deployed streamer, it assumes a nearly-horizontal, nose-high attitude, which causes it to glide while sliding backwards through the air, and:

As Reply #507 on this page of the NASASpaceFlight.com Forum says (see: http://forum.nasaspaceflight.com/in...topic=40328.500 , about halfway down the "screen-page"), SpaceX is--during launches in which this maneuver is practical--using the "tail-slider" boost-glide technique in order to bleed off much of the horizontal velocity of re-entering Falcon 9 first stages, so that the remaining onboard propellant can be utilized mostly for the vertical portion of the final descent. This will be particularly useful for the two boosters (strapped-on Falcon 9 first stages) of the Falcon Heavy, which will have appreciable downrange velocity when they separate from the core vehicle but must return to the launch site when flown in reusable mode. The propellant savings enabled by the boosters' "tail-slider" glide-back will permit the vehicle to orbit more payload mass than it could otherwise.

I hope this information will be useful.
__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR
Reply With Quote
  #2  
Old 05-02-2017, 07:54 AM
aeppel_cpm aeppel_cpm is offline
Ciderwright
 
Join Date: Apr 2013
Location: Burlington, WI
Posts: 446
Default

I'm guessing that they can use the grid fins to hold a slight angle of attack, and 'fly' the booster to some extent. (Adding some lift into the mix.) Don't Soyuz capsule do something a bit similar?

What caught my eye on this flight was the speed and alt gauges on the booster. It really bleeds off speed in the last 10k or so. Without a burn. Just lots of air.

When I first became a BAR, I spent a number of flights trying to deliberately back-slide a purpose-built rocket. I watched the sustainer of my Little Beth X-2 downscale (my first scratch build) backslide on its own, and dug into the articles on the subject.

I never succeeded. I think I (or my rocket, rather) fell victim to the modern 'shotgun' ejection charges. I was using a vent port under the nosecone as a thruster to turn the model horizontal. It always turned nearly 180 degrees and lawn darted.

My attempt at the 'Flying Stovepipe' design suffered from strong ejections, too. It's a Scout inside an annular wing. The ejection charge is supposed to kick the motor back against an extra long retainer clip and the momentum dislodge the Scout from the glider. Mine always blew the motor clean away.
__________________
Charles McGonegal
Ciderwright
AEppelTreow Winery & Distillery
Ad Astra Tabernamque!
Reply With Quote
  #3  
Old 05-02-2017, 09:00 AM
blackshire's Avatar
blackshire blackshire is offline
Master Modeler
 
Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 5,531
Default

Quote:
Originally Posted by aeppel_cpm
I'm guessing that they can use the grid fins to hold a slight angle of attack, and 'fly' the booster to some extent. (Adding some lift into the mix.) Don't Soyuz capsule do something a bit similar?

What caught my eye on this flight was the speed and alt gauges on the booster. It really bleeds off speed in the last 10k or so. Without a burn. Just lots of air.

When I first became a BAR, I spent a number of flights trying to deliberately back-slide a purpose-built rocket. I watched the sustainer of my Little Beth X-2 downscale (my first scratch build) backslide on its own, and dug into the articles on the subject.

I never succeeded. I think I (or my rocket, rather) fell victim to the modern 'shotgun' ejection charges. I was using a vent port under the nosecone as a thruster to turn the model horizontal. It always turned nearly 180 degrees and lawn darted.

My attempt at the 'Flying Stovepipe' design suffered from strong ejections, too. It's a Scout inside an annular wing. The ejection charge is supposed to kick the motor back against an extra long retainer clip and the momentum dislodge the Scout from the glider. Mine always blew the motor clean away.
*Nods* Yes (as they also mentioned in other postings on the NASASpaceFlight.com Forum), they're using the grid fins to literally fly the first stage, using its inclined body as a crude "flat plate" airfoil (the cylindrical first stage isn't a flat plate, of course, but it produces lift the same way an un-airfoiled flat plate does--simply due to the airflow meeting it at an appropriate angle to produce a lift force; it isn't as efficient as an airfoil, but it works). As you noted from the on-screen velocity read-out, this type of "airfoil" can easily be angled to generate a huge amount of drag, which--happily, as it doesn't require any expenditure of energy (beyond that needed to move the grid fins)--is just what is needed during that phase of the flight. Also:

The Soyuz (like the Gemini and Apollo capsules--Dragon, Orion, and Boeing's CST-100 Starliner capsule may also have this feature) does indeed also fly during re-entry, by means of a deliberately offset Center of Gravity, using its thrusters as an airplane uses its control surfaces. (Such capsules also can--and have been--spun to re-enter in purely ballistic trajectories if the guidance system fails, which has happened on a few occasions.) This capsule lifting flight capability was dramatically demonstrated by the translunar (Earth-Moon-Earth trajectory) Zond spacecraft, which were "stripped-down" (to save weight) Soyuz capsules--they performed dual-re-entry, aerodynamic "skip" maneuvers that brought them down in the Soviet Union. The U.S. Viking Mars landers, while still encased in their saucer-shaped aeroshell heat shields, also performed high-speed glides--under thruster control--during entry into Mars' atmosphere (the more recent Mars landers and rovers may also have done this). In addition:

I discovered tail-slider boost-gliders entirely by accident in the early 1990s. One day, while flying an MRC Wildfire (which is a long, narrow rocket, see: http://plans.rocketshoppe.com/mrc/m...RC+Wildfire.pdf ), its parachute failed to open fully. I was amazed to see it assume an inclined attitude and begin gliding--in a stable, steady manner--in wide circles, while sliding backwards through the air! It stayed airborne for the better part of a minute. Thinking it was a fluke, I launched it again (with its parachute deliberately reefed, in order to duplicate its more streamer-like drag characteristics when it had incompletely opened in the previous flight), and it glided the same way it had before. For the rest of its "career," I flew it that way. As well:

While a vent/thruster will work to "flip" a rocket into the correct attitude to glide backwards, it isn't necessary if the rocket's fineness ratio is sufficiently high--in fact, a thruster might shorten the glide duration (if it caused the model to "over-correct"; it would lose altitude in a fall while 'rocking' into its correct-for-gliding attitude). This is true of any boost-glider or rocket glider, but it's particularly significant and noticeable with low L/D gliders such as tail-sliders and lifting bodies, because they have high sink rates even under the best of circumstances. They do not soar (gain altitude) under normal conditions (thermal lift or slope lift would have to have a high upward velocity to make *these* gliders ascend, or even glide at a constant altitude! :-) ).
__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR
Reply With Quote
  #4  
Old 05-02-2017, 10:01 PM
Mugs914 Mugs914 is offline
Junior Rocketeer
 
Join Date: Nov 2012
Posts: 2
Default

I discovered tail sliding by accident as well, though not exactly the same concept.

At a launch back in the 80s my buddy's Estes Starship Vega had the shock cord break at ejection. As the nose cone drifted down on the parachute, the rest of it settled in to a tail-first glide better than a lot of purpose designed gliders. Of course we immediately drew up a rocket designed to do the same, but on purpose. Need to build it one of these days!
Reply With Quote
  #5  
Old 05-02-2017, 10:45 PM
Gus's Avatar
Gus Gus is offline
7/21/61
 
Join Date: Sep 2005
Location: North of Detroit
Posts: 1,769
Default

The Alway brothers actually patented this method of model rocket recovery which they call a "backslider." It does not use a streamer. The nosecone is glued in place. There is a small vent hole (1/4" or so for BT5 or BT20 rockets) in the body tube just below the nosecone. At ejection, the vented gas markedly changes the rocket's angle of attack, causing it to backslide.

You can see their patent here: https://www.google.com/patents/US6926576

Photos below show a competition backslider built 10 years ago by my daughter. We were at a contest here in Michigan and her Edmunds rocket glider disintigrated just above the launch pad. No possiblility of a second flight. I had a very sad young rocketeer.

Bob Alway was there, saw what happened, and suggested salvaging the balsa and using it to make fins for a backslider. Peter contributed the nosecone, Bob contributed the 34" BT5 tube and a paper punch. Emma cut the fins, glued them on by eye, punched the vent hole, glued the nosecone in place, and taped a launch lug on the body tube. It flew just fine and backslid for about 15 seconds, if I remember correctly. Qualified flight! Happy rocketeer!

Lots of fun! Emma got Bob and Pete to sign the rocket, which still hangs proudly in our rocket room.
Attached Thumbnails
Click image for larger version

Name:  IMG_2344.JPG
Views: 16
Size:  136.6 KB  Click image for larger version

Name:  IMG_2345.JPG
Views: 14
Size:  89.2 KB  Click image for larger version

Name:  IMG_2346.JPG
Views: 24
Size:  116.5 KB  Click image for larger version

Name:  IMG_2347.JPG
Views: 15
Size:  86.9 KB  
Reply With Quote
  #6  
Old 05-03-2017, 09:01 AM
rocketguy101's Avatar
rocketguy101 rocketguy101 is offline
frustrated aero
 
Join Date: Sep 2006
Location: Duncan, OK
Posts: 692
Default

The Centuri Groove Tube would glide also...as others posted, we discovered this by accident, and oddly enough, it performed better than some of my boost gliders!
__________________
David Stribling
NAR 18402 SR
But it is rocket science!
Get yer Barrowmans here
Reply With Quote
  #7  
Old 05-03-2017, 03:48 PM
PeterAlway PeterAlway is offline
Intermediate Rocketeer
 
Join Date: Mar 2014
Posts: 35
Default

Quote:
Originally Posted by Gus
The Alway brothers actually patented this method of model rocket recovery which they call a "backslider." It does not use a streamer. The nosecone is glued in place. There is a small vent hole (1/4" or so for BT5 or BT20 rockets) in the body tube just below the nosecone. At ejection, the vented gas markedly changes the rocket's angle of attack, causing it to backslide.

You can see their patent here: https://www.google.com/patents/US6926576



If you scroll to the bottom of the patent, you will see that Blue Origin cites our patent in several of their patents.

The little devil on my left shoulder is suggesting I should use that to leverage some scale data out of spacex. But the little devil on my right shoulder is telling me that would be too much work. I'll be listening to the one on my right shoulder.

Peter Alway
Reply With Quote
  #8  
Old 05-03-2017, 10:26 PM
blackshire's Avatar
blackshire blackshire is offline
Master Modeler
 
Join Date: Jan 2009
Location: Fairbanks, Alaska
Posts: 5,531
Default

Quote:
Originally Posted by PeterAlway
If you scroll to the bottom of the patent, you will see that Blue Origin cites our patent in several of their patents.

The little devil on my left shoulder is suggesting I should use that to leverage some scale data out of spacex. But the little devil on my right shoulder is telling me that would be too much work. I'll be listening to the one on my right shoulder.

Peter Alway
I thought the left-shoulder denizen was a little angel--or unicorn... :-) SpaceX already offers a BT-60 size "Falcon 9 and Fairing" model rocket kit (and Boyce Aerospace Hobbies makes 3D printed scale accurizing parts for the Falcon 9). Also:

In a 1950s-vintage book that I read over 30 years ago, the Mars Snooper--an actual proposed design that inspired the classic Estes kit--was shown in an illustration. It was designed to fly backwards in the Martian atmosphere (its "V-planform" tail fins acted as wings, while its forward canard surfaces served as tail surfaces during atmospheric flight), as a nuclear-powered jet aircraft. The nozzle of a nuclear rocket engine in its base doubled as the nuclear turbojet's air intake.
__________________
Black Shire--Draft horse in human form, model rocketeer, occasional mystic, and writer, see:
http://www.lulu.com/content/paperba...an-form/8075185
http://www.lulu.com/product/cd/what...of-2%29/6122050
http://www.lulu.com/product/cd/what...of-2%29/6126511
All of my book proceeds go to the Northcote Heavy Horse Centre www.northcotehorses.com.
NAR #54895 SR
Reply With Quote
  #9  
Old 05-04-2017, 12:25 AM
LeeR's Avatar
LeeR LeeR is offline
Retired with Way Too Many Kits
 
Join Date: Jun 2007
Location: Colorado
Posts: 1,632
Default

Buy your Mars Snooper print of the original Frank Tinsley artwork here:


Click image on webpage to learn more about the work.

http://www.plan59.com/prints/prints188.htm
__________________
Lee Reep
NAR 55948, L2

Projects: Mars Snooper, Viper
In the Paint/Detailing shop: Estes Saturn 1B, Der Saturn Max
Completed!: Red Nova, STM-Bandit, Honest John
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 09:51 AM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe 1998-2018