Flight Testing - Airframe vs Personal Parachute

I figured i should start a new thread for this subject, didn't want to confuse the other one.

I was doing more research last night, BRS says on their web site that airframe parachute systems for experimental aircraft range from $3000 to $12,500

I decided to look & see what Spruce was selling personal parachutes for, they run from approx $1900 - $2600

I am looking at this a couple ways, 1) after spending a lot of $$$ on the project it would be real nice to be able to save it if there is a problem in testing, but 2) if it has a serious flaw is it worth saving, and the airframe chute adds weight & forces design compromises.

I figure if I need a chute it will probably be in the flight testing phase (unless there is an engine failure at some time later)

Another point to consider is the testing will be done in Central Illinois, there are lots of big flat fields around here.

Anyone have any thoughts? Should I continue trying to fit an airframe parachute or should I just wear one for testing? (I may decide to wear one anyway just in case, even if it has an airframe chute)

My thoughts, and only mine, regarding parachutes. The only time I would deploy an airframe parachute is when I have experienced a catostrophic airframe failure. If the airplane is even glidable, glide it to the ground. Remember, once that chute is deployed, you cease to be a pilot and become a passenger, with no means whatever to influence where you land. As to a personal parachute - it will also add weight to your airplane (unless you plan on leaving it on the ground), is likely to be uncomfortable and may not even fit into the cockpit of your homebuilt (usually not much room in those fellows). If you have a lot of off airfield landing possibilities and are concerned about weight, I'd opt for a really good inspection of the airframe, to ensure that the wings aren't going to come off, and do your test flying where you can land with minimal chances of running into a tree, fence or high wires. If you take my advice and it comes to disaster, I will deny ever having said anything like this. Someone else must have hacked my computer.....

PS. Whether you deploy an airframe parachute or a personal parachute, remember, you must be high enough for the chute to fully deploy, otherwise it will do little to save you or your airplane....

Jerry, my main concern is an unrecoverable stall/spin situation. As long as I make good welds airframe failure shouldn't be a problem.

It would help to know what you are building. The flight test program for the n-th one of a design or kit that has a lot of flying examples is organized differently than the flight test program for an original design.

There are much more knowledgeable folks out there than me, but I will offer the advice that slow flight, stall, and spin testing is a step by step, incremental process. If you do it that way, you are much less likely to be surprised than if you load the airplane up, blast off, and see what happens.

The FAA has an Advisory Circular titled Flight Testing Homebuilt Aircraft. You might give that a read.

If you intend to try a spin in your new aircraft are not completely comfortable doing all of the possible types of spins, I will suggest getting some training. Aircraft spin behavior is an very interesting topic that has gotten many thousands of man hours of investigation.... and every new airplane is still handled very carefully when the flight test program gets to that topic. If you have never seen a power on flat spin from the inside, you should pay someone to show you before you try spins in your new pride and joy. Its is much better to be over-prepared than find youself going "oh wow what do I do now". I hope that you will consider such training in preparation for your first flight as part of the educational experience.

If you are building a design that has many examples already flying, and you pay attention to rigging and CG, you make it much less likely that you will be using your parachute. A large part of spin behavior is a function of CG, power, and rigging.

Best of luck,

Wes
N78PS

It is pretty much a new design - loosely based on a LongEZ but bigger (slightly wider & longer with a baggage compartment behind the rear seat). Greater lifting area to compensate for weight. The preliminary numbers say it will be OK, but you never know til you fly it. And I'm using tube & fabric. :)

I can't go any farther with the structural design until I figure out where the chute is going (or if I have one), so this is a major factor in the design.


Oh, and I don't PLAN on doing spins, but if it does it may not be recoverable if the aerodynamics aren't right.

I will suggest that Martin Holman's Test Flying is an excellent starter book for someone like yourself.

I will also suggest that a typical back parachute weighs 15 lbs. You can go to the different parachute manufacturers web sites (Strong Parachutes, National Parachutes, Softie, etc.) to get exact weights if you need them. Having worn a parachute for many years for different reasons I will advise that mind set is very important. Your flight test should include an altitude floor for abandoning the aircraft if you are not in normal flight. Successful use of a parachute requires the mental commitment to use it at a predetermined time. Time won't be on your side.

I recall Sport Aviation had an interesting article about some of the issues with, I think, Velocity aerodynamics and a test flight the got into a deep stall situation where the pilot rode it down to the Gulf of Mexico and tried the aircraft out in boat mode. My memory of the article is a little hazy but I recall that it is worth reading.

Best of luck,

Wes
N78PS

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Originally Posted by WLIU

I will suggest that Martin Holman's Test Flying is an excellent starter book for someone like yourself.

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I will check that out when the time comes

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Originally Posted by WLIU

I will also suggest that a typical back parachute weighs 15 lbs. You can go to the different parachute manufacturers web sites (Strong Parachutes, National Parachutes, Softie, etc.) to get exact weights if you need them. Having worn a parachute for many years for different reasons I will advise that mind set is very important. Your flight test should include an altitude floor for abandoning the aircraft if you are not in normal flight. Successful use of a parachute requires the mental commitment to use it at a predetermined time. Time won't be on your side.

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I never had any desire to jump out of a perfectly good airplane, but if it isn't..... Well, lets just hope my number crunching is right.

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Originally Posted by WLIU

I recall Sport Aviation had an interesting article about some of the issues with, I think, Velocity aerodynamics and a test flight the got into a deep stall situation where the pilot rode it down to the Gulf of Mexico and tried the aircraft out in boat mode. My memory of the article is a little hazy but I recall that it is worth reading.

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I remember that one - he was lucky. Niel Hunter was killed in the one he was flying when wake turbulence put him in an inverted flat spin. Something like that is what scares me.

Mike, I understand that you will have a pusher prop. I expect that you will have a bail out procedure worked out. I recall once asking a USAF pilot in RVN how he got out of his O-2. He said there was a procedure in the book, but knew of no one that had ever used it. Army Huey crews were once required to wear chutes for a short time mid 60's. Someone woke up and rescinded that policy.
Too bad that you can't rent a BRS for the Phase one. Jerry has some good points.
Bob

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Originally Posted by Bob Dingley

Too bad that you can't rent a BRS for the Phase one.

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Yea, that would be ideal, I could just put it in the baggage compartment & then remove it if testing went well. It would be easy enough to tie it into the crossmembers.

(maybe I smell a business opportunity here?)

Right now I'm sort of of the opinion that if after testing I feel it needs a chute something else probably needs fixed.

I haven't thought much about a bailout procedure, but since the whole thing is still a bunch of autocad data right now I've got some time. I know enough to know I would need to be well clear before pulling the chute.

If the only concern is for the testing period, I'd go for a personal parachute. It's cheaper and has no long term maintenance issues the BRS does.

BRS systems are great if one deals with rough terrain - I'd much rather ride into rocks and trees within an aircraft than meet it with my soft pink flesh beneath a chute. Tree landings are no fun. Ditto landing on rocks. Been there, done that, got the bauble for my chest.

Engine off is standard procedure for BRS systems - tractor or pusher - and I would assume it would be the same for bail-out, so I don't think it's a concern if the risers are routed correctly.

As to spinning, if the aircraft isn't designed for them to begin with I wouldn't do them. My plane is definately not rated for aerobatics and I won't be putting spins in the flight test program (though I did spin training in a Champ as part of my personal training plan).

Well, after pondering the matter some more, I believe I will add a little extra structure around the baggage compartment to attach the harness to if I decide to temporarily install a BRS in the cargo bay, but right now I am leaning toward just wearing one.

The one thing I haven't seen mentioned is that a rocket deployed BRS can save you lower than a personal parachute, by the time you unbuckle your seat belt, exit/clear the aircraft, and deploy the chute. I believe there have been successful BRS saves from as low as 200'.

That said, I'm inclined to go with a personal parachute when (if!) I build the design I'm working on. I'm more concerned with problems testing the edges of the aerobatic flight envelope than I am with structural or handling issues taking off or landing, and a personal parachute is lighter and cheaper than a BRS.

Canards are designed to never stall and therefore never spin. You should design a good anti-stall margin into your flight characteristics (read as canard always stalls first at worst possible aft CG plus some safety margin).

If I may offer some food for thought. The FAA requires that even aircraft that are placarded against spins be designed and flight tested to demonstrate that they recover from a one turn spin. And you may not be aware that all light twins are spin tested.

And as for parachutes in helicopters - Helicopter flight test crews wear parachutes and use them successfully. I know of at least two incidents where parachutes saved crews. If you do not think that wearing a parachute makes sense, then you should learn more about what can go wrong in a helicopter.

Be carefull up there.

Wes
N78PS

Hi Wes, I was thinking way back to 65, when the 11th Air Asault formed up in the states and chutes were issued. When the Div got to Nam it was redesignated 1st Cav(Air Mobile) and Mel Gibson was a Bn CO. Since they hardly climbed up out of the "bozzo sphere" Chutes were no help. They were ordered turned in to supply. One of my copilots was a test pilot for Charlie Kaman and wrecked at least one H2 with no chute.

Bob
ATP (H) ex Dustoff 100

It seems you are predisposed to a chute ... and I think that is prudent myself. Rather than consider for just the test phase, why not embrace a BRS as a permanent measure to provide peace of mind throughout the flying year for you....and your passenger. As mentioned, there are rare but possible events of poor terrain, unexpected turbulence, disorientation, health incapacitation, visibility, panic, and more, that may make your decision to go BRS a no brainer if it happens. I know there are colorful stories of skilled pilots successfully dealing with these events, but I myself will opt for the benfits of this advancement in flying technology, and its proven record of success. I could always get another plane (maybe :).

Parachutes - There are a number of situations where a parachute can help you, and a number of situations where they can not help you. Whether or not you wear a parachute depends on whether you are exposing yourself to the first set of situations, how often, and for how long. They are a tool.

There was an incident a few years ago where during a flight test a helicopter tail rotor transmission seized. I am told that the last crew member left the aircraft at something like 300', was thrown well clear of the rotating aircraft, and got an open parachute before reaching the ground.

If you are an average pilot flying a factory aircraft then you are extremely unlikely to need a parachute. If you are flight testing a well known homebuilt kit, you are likely to need a parachute for the hours spent verifying that your example behaves like the rest of the population of that aircraft. If you are flight testing a completely new design, you are likely to need a parachute for the (more) hours that you spend verifying the entire spectrum of flight characteristics and structural integrity. And if you are a guy like me where an average flight involves +6G and -3G (aerobatics), and who thinks that flying without an airplane is routine (skydiving), you wear a parachute a lot.

A parachute won't save you from every situation. It just gives you an option when all of the decisions available have bad consequences.

Y'all be carefull out there.

Wes
N78PS

Just thought that I'd add a caution about a parachute giving you a false sense of security. It won't save you from all accidental failures so don't think you need to push the envelope past what is safe.....

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Originally Posted by rosiejerryrosie

don't think you need to push the envelope past what is safe.....

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That isn't likely to happen...

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Originally Posted by b2p

why not embrace a BRS as a permanent measure

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it adds weight, and it is becoming a royal pain to integrate into the design - that said I'm not ruling it out, I think I figured out how to mount one in a rack over the baggage compartment under a fairing

although I am wondering if I couldn't just mount a medium sized extraction chute back there, manually pop the fairing & accomplish the same thing

Does the BRS system typically not scrap the airplane anyways? What's the descent rate as you hit the ground? Whats the structural damage from the "impact" of the chute deploying while your in a spin, etc? I'm not sure the BRS will save your plane, I guess the focus is more on saving you!

I think you might have a business idea though....buying a BRS then leasing it out. not a bad idea

I would have both personal and airframe chute for testing. Reason - while spin testing a local design here in South Africa the plane got into an un-recoverable spin. The airframe chute was deployed but failed to be come out of the aircraft. The two test pilots then had to exit the aircraft and were saved by their personal chutes. Had they relied on the airframe chute they would not have survived. Do you know your airframe chute will work properly? Theirs did not.
Neil

I find this thread to be of particular interest, since I've been one of the engineers with BRS for 25 years (as of December). I have just a few quick comments regarding some of the posts in no particular order.
1. One of the biggest mis-representations regarding deployment of a whole aircraft recovery device is the idea that "you're giving up control" to the parachute. Where its true that you don't have much directional control (thats another discussion), at the time you actually need a ballistic parachute, you're NOT in control of the situation anyways - events are going to occur no matter what input you may apply. The parachute, which is merely another aerodynamic device on the aircraft similiar to ailerons, flaps etc., is activated by the pilot to regain control of the situation.

2. Parachute deployments are always preceeded by unforeseen events. NO ONE would willingly fly ANYTHING if they believed that something horrible WILL occur on that flight. Even in the very early UL days when people were flying things made from hardware store crap, less than 25% of deployments were due to something associated with aircraft structure. Its the unforeseen things that will get you.

3. There is absolutely no question regarding altitude required for safe deployment when comparing a pilots safety rig to a ballistic system. We just recently had a Cessna 182 save from less than 300' AGL. That is NOT a possibility with a pilots rig at all. Even an experienced sky-diver would need to be out and clear of the aircraft by 1000' agl. Keep in mind, most emergency conditions that have occurred which resulted in a ballistic parachute deployment occurred below pattern altitude.

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Originally Posted by Jeff Peltier

most emergency conditions that have occurred which resulted in a ballistic parachute deployment occurred below pattern altitude.

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Interesting - I was not aware of that

Here's a thought. When I was rodeoing in my Bonanza I used it like one would a car. Put over hundred hours a month on it. I figured I could put it down in a creek bed in the mountains and survive. Only thing I worried about was losing a tail or wing or fire at altitude and not being able to get down to ground before it burned up. So, I guess if I had to chose between the two, I'd take the personal chute. Could get away from burning plane (maybe if lucky) and could bail out if lost part of the plane (maybe, if luckey). Best deal would be to have both types. If plane on fire, bail out. If lose a wing or tail, use the BRS. Otherwise, don't fly at night or in the clouds, and don't jump out of a flying airplane.

An airframe parachute is a design decision and typically requires airframe modification for it to work properly.

A personal parachute for the test pilot is not a bad idea. Particularly for flutter testing, and spin testing. I do not own my own personal parachute. What I have done is contact a local skydiving group and see if they have an older chute that they will rent out. The fixed me up with a nice thin pack chute and only charged my $25 for a days rental for the relevant flight tests. I have had more than one engine failure in my career and have never needed a chute for an engine failure. If fact, I never even damaged an airplane because of an engine failure. Your mileage may vary.

I know there is a skydiver group in Vandalia, Illinois. There may be others closer to your location.

No one has mentioned a spin chute, much smaller and goes out the rear to get the pointy end going forward again. Most designs can be later released when things are back under control. When using a whole aircraft chute or a personal chute, the last thing that should be on your mind is the airplane (save that precious cargo). One can't go through ALL the scenarios, but try. For example, will the whole airplane chute work if the airplane is spinning (and/or tumbling, inverted, etc). In addition can you personally get out of the airplane if you had to? And practice that over and over and over.

I talked to a guy at OSH one year about getting out of his Berkuit (sp) - long EZ type airplane. He had a small hole through the panel area that his legs stuck through (no walled tunnel for his legs). If the airplane were in any other attitude than straight and level (not normally the condition that one is leaving the airplane under), his legs would have been stuck (flailing around) behind the panel.

As mentioned earlier, a canard should be designed so the canard stalls first ... always. All single engine TCd airplanes are fully spin tested (regs ... with some exemptions like the Cirrus designs). No multi-engine TCd airplanes are spin tested (no regs). And, before I get flamed, yes military fighter jets are all spin tested ... their flight envelope is a little different.

Great discussion.

I work with a gentleman who was the former chief designer at Piper. He tells me that spin chutes were mostly a failure in use. I understand that a number of anti-spin devices (small parachutes, rocket motors, etc) were tried and none were found to be reliable. Did not go into the specifics with him. The bottom line was that the Piper flight test staff wears parachutes and plans to exit the airplane if needed. For what it is worth, large scale RC models are used to do a lot of the pre-first flight evaluation of the potential spin characteristics of new designs. If you are really concerned about how your original design might perform, work the math to appropriately scale it down and build a flying model. I understand that Burt Rutan started that way.

Oh, and yes light twins are in fact spin tested. I have had some interesting and educational discussions about spin testing twins with my co-worker. But I do not suggest that you explore that topic in your own airplane.

Best of luck,

Wes
N78PS