Ballistic Parachute for the RV8

[camillodinucci]

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.

[rmarshall234]

Greetings,
That is quite the project you are considering. Butler Parachutes in the US has made “ lap “ type parachutes in the past. If you haven’t given up completely on the idea of a PEP, you might want to contact them and see if they can help you.
Good luck.

[Pilot135pd]

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.

[Tall_Order]

Originally Posted by Pilot135pd

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?

Originally Posted by camillodinucci

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!

[warmi]

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

[N546RV]

Originally Posted by Tall_Order

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.

[PhatRV]

Originally Posted by N546RV

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.

[DanH]

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.

[camillodinucci]

Originally Posted by Tall_Order

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.

[Tall_Order]

Originally Posted by camillodinucci

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.

Thanks for the offer; PM sent

Regarding bridle strap routing (and my plane is a bit different due Fastback), I'll share part of my modification in case you may want to consider something similar depending what chute deployment angles you predict.

I welded a nut on top of my aftermarket roll bar before powder coating and installing it a couple months ago. A bracket that engages with the nested canopy frame will be bolted to it. I expect a full width nested frame will increase my "safe" areas as well as help support the canopy in the event a strap is in a position to exert a side load (thankfully the angles required for that are near perpendicular to the strap ).

There are many on this forum better at engineering so as always, I welcome input!