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  #1  
Old 09-10-2023, 07:40 PM
camillodinucci camillodinucci is offline
 
Join Date: Feb 2020
Location: Brazil, S?o Paulo - SP
Posts: 11
Default Ballistic Parachute for the RV8

Hello, I am finishing the assembly of my RV-8 and I intend to perform acrobatics with it. It turns out that I am very tall 2.00 meters height and weight 100 kg (220 lbs), being tall limits the possibility of using a parachute on the back or even a seat because when gaining height in the seat my knees hit the instrument panel when commanding the rudder pedals.

Having explained all this, I decided to install a BRS parachute in the RV-8, analyze the efforts in the structure and carry out the installation of reinforcements, the calculation of the CG, etc.

This was the way I found to perform the acrobatics with a little more tranquility.

If you could share your experience installing these devices, I would like to know more, and how the RV-8 performs afterwards.

Below are the project photos.
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  #2  
Old 09-10-2023, 07:49 PM
rmarshall234 rmarshall234 is offline
 
Join Date: Jun 2008
Location: San Diego, CA
Posts: 620
Default

Greetings,
That is quite the project you are considering. Butler Parachutes in the US has made ď lap ď type parachutes in the past. If you havenít given up completely on the idea of a PEP, you might want to contact them and see if they can help you.
Good luck.
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  #3  
Old 09-10-2023, 10:21 PM
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Pilot135pd Pilot135pd is offline
 
Join Date: Jan 2019
Location: Vaca Moo Airport - TA37 in EAST TEXAS
Posts: 2,110
Default

I like your project and I had the same problem with my RV8. If I had anyone in the rear seat I could only fly with 5 gallons of fuel if I wanted to stay in a legal W&B envelope.
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  #4  
Old 09-11-2023, 04:54 PM
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Tall_Order Tall_Order is offline
 
Join Date: May 2020
Location: Alberta, Canada
Posts: 58
Default I am experimenting with the BRS/WARPS idea

Quote:
Originally Posted by Pilot135pd View Post
If I had anyone in the rear seat I could only fly with 5 gallons of fuel if I wanted to stay in a legal W&B envelope.
Granted, a chute pack would weigh more than a battery, but do not a lot of RV-8s opt for a rear mounted battery to bring C of G aft? Could not a fwd battery (with that mass now at an inverse arm) and a specific engine/prop combo make the rear seat usable at all?

Quote:
Originally Posted by camillodinucci View Post
If you could share your experience installing these devices, I would like to know more, and how the RV-8 performs afterwards.
I am modifying a RV-7 BRS kit for a RV-8A Fastback(Turtledeck remains clear and fuselage height for aft straps is similar) but there is a ways to go on this install. If you have info about of a flying RV-8 with this system, please post!
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RV-8A Fastback

Fuselage SB about 2/3 done, pre-close inspection complete, Fastback mod complete, working on electrical/avionics
Wings SB haven't started yet... (LCP hold)
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Donated 2022
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  #5  
Old 09-11-2023, 06:09 PM
warmi warmi is offline
 
Join Date: Mar 2021
Location: Frankfort,IL
Posts: 31
Default

It is unfortunate that BRS ( or GRS or Magnum ) is not a standard option as it is for instance on Zenith planes.
These things do save lives … like this guy here , had it not been for BRS he would have been 100% dead ( much easier to pull a handle than try to bail yourself out )

https://youtube.com/watch?v=4a8cntPd...z0Ztazsz0h4cI4
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  #6  
Old 09-11-2023, 11:16 PM
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N546RV N546RV is offline
 
Join Date: Aug 2010
Location: Brookshire, TX
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Quote:
Originally Posted by Tall_Order View Post
Granted, a chute pack would weigh more than a battery, but do not a lot of RV-8s opt for a rear mounted battery to bring C of G aft? Could not a fwd battery (with that mass now at an inverse arm) and a specific engine/prop combo make the rear seat usable at all?
Yeah, I'm surprised to hear that about a rear-seat passenger. My impression has always been that the -8s tend to have issues with the CG being too far forward when solo. There are a couple threads floating around with people talking about ways to put easily-removable ballast back in the tail to make the plane fly better solo.
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  #7  
Old 09-12-2023, 06:57 AM
PhatRV PhatRV is offline
 
Join Date: Mar 2018
Location: KAJO
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Quote:
Originally Posted by N546RV View Post
Yeah, I'm surprised to hear that about a rear-seat passenger. My impression has always been that the -8s tend to have issues with the CG being too far forward when solo. There are a couple threads floating around with people talking about ways to put easily-removable ballast back in the tail to make the plane fly better solo.
When I did the W&B for my RV8, it was near the rear CG datum at 1800# with full fuel and a big passenger, and full weight in the rear baggage compartment. As the fuel gets to minimum, the CG shifted past the rear datum by a few percent.

I have the light weight fixed pitch composite prop. But I think having a heavier constant speed prop will get a better balance at gross weight. There was a story posted here about a RV8 with passenger returning from Reno Air Race and the pilot experienced PIO when landing with a light fuel weight.
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  #8  
Old 09-12-2023, 06:59 AM
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DanH DanH is online now
 
Join Date: Oct 2005
Location: 08A
Posts: 11,724
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I've worked with several BRS and Second Chantz installs on light stuff. One aspect seldom considered is decapitation.

Given an airframe failure, there is no way to predict the attitude of the fuselage at deployment. Watch old BRS movies and you'll often see tumbling balls of junk. So, it's really helpful to have some structure around the cockpit in order to keep the bridle straps away from the pilot. If the canopy opens while a bridle is across the torso or neck...

Something like a Cirrus has an enclosed cockpit, here notable for its roof structure to keep the straps out.

Related, designers often try to arrange the rocket system so it fires aft and up and hangs upright. That's terrific if the assumed reason for deployment is an engine failure with the airframe gliding straight and level. It's entirely appropriate for a family airplane with a power failure in a bad place, and it sells well in the pictures. However, given an aerobatic airframe failure, it doesn't matter if the deployment is out the side or through the belly, because there is no way to predict "up". The only high probability is shooting more or less rearward, as even the balls of junk eventually tend to assume heavy end down.

Bottom line, you may want to re-think the 4-strap suspension, as it pulls the forward straps across the cockpit if there is any activity in the roll axis. Even if the strap does not reach the meat servo, a canopy collapse won't be pretty. A system with two aft straps doesn't guarantee no cockpit involvement, but it a lot less likely.
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  #9  
Old 09-19-2023, 01:30 PM
pv9 pv9 is offline
 
Join Date: Feb 2022
Location: San Jose
Posts: 39
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Quote:
Originally Posted by DanH View Post
I've worked with several BRS and Second Chantz installs on light stuff. One aspect seldom considered is decapitation.

Given an airframe failure, there is no way to predict the attitude of the fuselage at deployment. Watch old BRS movies and you'll often see tumbling balls of junk. So, it's really helpful to have some structure around the cockpit in order to keep the bridle straps away from the pilot. If the canopy opens while a bridle is across the torso or neck...

Something like a Cirrus has an enclosed cockpit, here notable for its roof structure to keep the straps out.

Related, designers often try to arrange the rocket system so it fires aft and up and hangs upright. That's terrific if the assumed reason for deployment is an engine failure with the airframe gliding straight and level. It's entirely appropriate for a family airplane with a power failure in a bad place, and it sells well in the pictures. However, given an aerobatic airframe failure, it doesn't matter if the deployment is out the side or through the belly, because there is no way to predict "up". The only high probability is shooting more or less rearward, as even the balls of junk eventually tend to assume heavy end down.

Bottom line, you may want to re-think the 4-strap suspension, as it pulls the forward straps across the cockpit if there is any activity in the roll axis. Even if the strap does not reach the meat servo, a canopy collapse won't be pretty. A system with two aft straps doesn't guarantee no cockpit involvement, but it a lot less likely.
Have you successfully installed either BRS, Galaxy or Second Chantz on a RV-8? BRS routes the straps entirely outside the cabin on the 7 and 9 but they donít have a system for the 8.

BRS told me this morning that they started an RV-8 project years ago and gave up. The person could not tell me why.
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  #10  
Old 09-20-2023, 06:16 AM
camillodinucci camillodinucci is offline
 
Join Date: Feb 2020
Location: Brazil, S?o Paulo - SP
Posts: 11
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Quote:
Originally Posted by Tall_Order View Post
Granted, a chute pack would weigh more than a battery, but do not a lot of RV-8s opt for a rear mounted battery to bring C of G aft? Could not a fwd battery (with that mass now at an inverse arm) and a specific engine/prop combo make the rear seat usable at all?



I am modifying a RV-7 BRS kit for a RV-8A Fastback(Turtledeck remains clear and fuselage height for aft straps is similar) but there is a ways to go on this install. If you have info about of a flying RV-8 with this system, please post!
I am completing the installation of the parachute on my plane; these drawings I have attached are from the engineering project for the equipment installation. Once it's finished, I'll send it to you.
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