Forced air from flight at engine nozzle, added thrust to a recessed engine?

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ChrisLentz

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I have a little problem.

I had a dead motor in my motor mount, as I was pulling it out the last inch of motor mount broke off leaving me with a recessed motor mount by 1 calibre.

Krushnic effect assumingly probable, I figure I need to add air in there. Scoops on the side would add more oxygen to the burn.

Potentially act as air brakes after burnout.added thrust.pnglabelle 1 3d induction.jpg

The airbrakes would come in handy for a level 1 cert flight below 750 feet.

Am I crazy or would this add extra thrust at burnout then have enough drag to reduce the altitude to comply with the local clubs waiver?

Can induction like this be simmed in Rocksim?
 
ChrisLentz said:
I have a little problem.

I had a dead motor in my motor mount, as I was pulling it out the last inch of motor mount broke off leaving me with a recessed motor mount by 1 calibre.

Krushnic effect assumingly probable, I figure I need to add air in there. Scoops on the side would add more oxygen to the burn.

Potentially act as air brakes after burnout.View attachment 298837View attachment 298838

The airbrakes would come in handy for a level 1 cert flight below 750 feet.

Am I crazy or would this add extra thrust at burnout then have enough drag to reduce the altitude to comply with the local clubs waiver?

Can induction like this be simmed in Rocksim?
Click to expand...

I have no comment on your forced air idea, however I would say that the introduction of the Krushnic effect is a strong possibility. This is something I deal with on one of my rockets, which uses a bell nozzle retainer. It is the only rocket I have where the sims are way off and the rocket never reaches it's potential, so my conclusion is the Krushnic effect plays a role and robs about 30% performance.

Having said that I don't think the solution you are pursuing is necessarily the best course of action. I would keep it simple and try to fix your MMT.
 
If the air intakes are large enough they may act as a thrust augmenter. Try it on a G motor and find out.


Richard
 
Hmmm. My two cents. If the MMT is over one caliber up you will certainly experience the Krushnik effect. Adding air can defeat Krushnik but will not augment thrust. The vents/ 'air brakes' will add drag both during and after boost. Use electronics or plan the delay very carefully. While experiment are generally discouraged for a Cert flight, the only other people you have to satisfy are the RSO and the ones that will sign off. I'd have more worries about the structural integrity of what's left if part of the mount can rip out (???) Maybe that's 4 cents.
 
Not saying it would be a cert rocket but if the air brakes work to lower the altitude and there is enough lift off velocity...anything is possible.

Trying to innovate my own design out of necessity. I would hate to scrap it and if it works...cool.
 
I did not understand anything so very stupid or something genius :)
 
tmacklin said:
Here, maybe this will help...

[video=youtube;Ac7G7xOG2Ag]https://www.youtube.com/watch?v=Ac7G7xOG2Ag[/video]
Click to expand...

:y:What a bunch of malarky!!! :facepalm: Anyone with 1st grade edgeamacation knows that the Turbo Encabulator will only produce 6 Sub-o-Bamas with the "Normal-Lous-0-Delta":shock: But if you use a "Xtram-Nelumbo-Nucifera-Gamma" you will trump that output by 1000k Reganites:wink:
 
I say try it and see what happens. Be sure and record it just in case the result is worth sharing!!

ChrisLentz said:
Scoops on the side would add more oxygen to the burn.
Click to expand...
No they won't. All the oxygen for the burn is contained inside the motor chemicals. The scoops won't help it to burn better or worse.

mpitfield said:
the introduction of the Krushnic effect is a strong possibility.
Click to expand...
Use something on the launch rod to hold the rocket an inch or so above the blast plate and you'll easily avoid that. Our club has a clothes pin on each rod, and I have a spring support I bought from Odd'l Rockets that stays on mine. I bought it after losing a rocket to the Krushnic Effect. It was actually cool to watch it sit still as the back of the rocket melted, but once was enough.
 
Arent there a few russian rockets/missile with induction, either for L propellant or thrust vector on solid motor? I picture the VTS rocket and always wondered why.
 
ChrisLentz said:
I have a little problem.

I had a dead motor in my motor mount, as I was pulling it out the last inch of motor mount broke off leaving me with a recessed motor mount by 1 calibre.

Krushnic effect assumingly probable, I figure I need to add air in there. Scoops on the side would add more oxygen to the burn.

Potentially act as air brakes after burnout.View attachment 298837View attachment 298838

The airbrakes would come in handy for a level 1 cert flight below 750 feet.

Am I crazy or would this add extra thrust at burnout then have enough drag to reduce the altitude to comply with the local clubs waiver?

Can induction like this be simmed in Rocksim?
Click to expand...
Recessing the engine inside the airframe creates a hot gas recirculation zone within in the lower airframe.

The effect is similar to a venture pump where a high velocity fluid flow generates a vacuum in pulls ambient air into the exhaust flow. The flow generates a vacuum at the base flange of the airframe so air at the edges of the hot gas plume moves backwards along the internal wall of the airframe and along the lower bulkhead toward the nozzle exit were the flow pulled to back out of the airframe. This recirculation of hot gases heats the aft bulkhead and in larger rocket can damage the base of the rocket. The Saturn 5 had vents around the lower airframe to suck air in from the sides of the airframe to reduce the circulation and base heating.

You do not need scoops as the base vacuum will pull the air in to reduce the base vacuum. The oxygen in the air does not enhance thrust, however there is a slight bit of thrust augmentation due to the increased mass flow, and a definite decrease in base drag. You rocket may actually go slightly higher because of the base drag reduction.
 
Mushtang said:
Use something on the launch rod to hold the rocket an inch or so above the blast plate and you'll easily avoid that. Our club has a clothes pin on each rod, and I have a spring support I bought from Odd'l Rockets that stays on mine. I bought it after losing a rocket to the Krushnic Effect. It was actually cool to watch it sit still as the back of the rocket melted, but once was enough.
Click to expand...

The Krushnik effect is caused by a motor being recessed in the body. Using a standoff will avoid Bernoulli Lock where the low pressure area at the base actually holds the rocket on a flat surface.
 

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