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Thread: Flight Testing - Airframe vs Personal Parachute

  1. #1
    Mike Switzer's Avatar
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    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)

  2. #2
    rosiejerryrosie's Avatar
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    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....
    Last edited by rosiejerryrosie; 11-07-2011 at 08:42 AM. Reason: Adding a PS.
    Cheers,
    Jerry

    NC22375
    65LA out of 07N Pennsylvania

  3. #3
    Mike Switzer's Avatar
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    Jerry, my main concern is an unrecoverable stall/spin situation. As long as I make good welds airframe failure shouldn't be a problem.

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    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

  5. #5
    Mike Switzer's Avatar
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    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.
    Last edited by Mike Switzer; 11-07-2011 at 12:59 PM.

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    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

  7. #7
    Mike Switzer's Avatar
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    Quote Originally Posted by WLIU View Post
    I will suggest that Martin Holman's Test Flying is an excellent starter book for someone like yourself.
    I will check that out when the time comes

    Quote Originally Posted by WLIU View Post
    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 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.

    Quote Originally Posted by WLIU View Post
    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.
    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.

  8. #8

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    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

  9. #9
    Mike Switzer's Avatar
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    Quote Originally Posted by Bob Dingley View Post
    Too bad that you can't rent a BRS for the Phase one.
    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.

  10. #10

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    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).
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

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