Why was the AR-5 retired from use?

Discussion in 'General Experimental Aviation Questions' started by andytk58, Sep 3, 2011.

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  1. Sep 3, 2011 #1

    andytk58

    andytk58

    andytk58

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    Evening,

    New member here, I'm a recently qualified microlight pilot in the UK (very similar to Sport Pilot in the USA, fixed wing MTOW 990lbs, stall <35kts etc day VFR only)

    I've always been interested in aircraft and would love to buy either my own aircraft, or a share, perhaps next year. I have however been looking around at various homebuilt aircraft as this is a route I would maybe consider going down one day.

    A while ago I stumbled across the AR-5 website, and ended up buying the construction video from the site.

    As I understand, the AR-5 is the only aircraft to ever use the thin sandwich hotwire styrofoam construction technique for its fuselage. This seems like a good way to make a plansbuilt light aircraft (although it doesn't get you away from sanding...:dis:)

    To be clear, this is quite different from the last-a-foam (urethane?) skinning method used on the Vision.

    Next month, I'll be on vacation in San Fransico and if I've got the time, I'll visit the Hiller museum there to have a look at the AR-5.

    My question, as per the title, is:
    Why did Mike Arnold stop flying the AR-5?
    And even then, why not sell it and allow someone else to continue using the aircraft prior to it being preserved?
    Does anyone know how many hours its got on it, and if the structure is still sound.

    As this method of construction is a one off, it would be interesting to know these things to see if its worth persuing.

    Andy K
     
  2. Sep 3, 2011 #2

    wsimpso1

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    I too have wondered if it returned to flight or if it was retired.

    I can not tell you what Mike Arnold's thoughts were, but I do know that he had an engine failure (broke something internal) and the AR5 had a forced landing. The plane came to a stop with the gear legs bent aft and the airplane was sitting nose down on the cowling. That wrecked the main gear and smacked the engine and firewall on the ground. In the case of other pilot-builders, some have decided to retire the bird rather than risk an in-flight structural failure.

    Anyone know any more about it?

    Billski
     
  3. Sep 4, 2011 #3

    Will Aldridge

    Will Aldridge

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    According to his video a soldered connection in the throttle linkage gave way and that was the reason for the engine failure. According to the video the gear mounts were undamaged and the engine mount bent absorbing the impact(no damage to primary structure that he had found). As of the recording date of the video he was planning on returning it to flight, but hadn't finished or maybe hadn't even started yet. Maybe he found something as he started digging into it? I have read as many articles as I could find on the plane and never came across a reason for retirement.

    Regarding your questions/assumptions about it's construction, it followed the methods made popular by Burt Rutan. There are many many more planes built using that method.
     
  4. Sep 4, 2011 #4

    billyvray

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    He did have the engine out and did return it to flight after it was repaired. He even made another video of the repairs and making molds during that time. I believe the aircraft was sold to someone and immediately donated to the Hiller museum, possible just for preservation. I don't think there was anything wrong with the aircraft at all.
     
  5. Sep 4, 2011 #5

    litespeed

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    The AR-5 has always been a inspiration to me. I have always dreamt of doing a similar plane but with a 110hp Simonini , same weight as rotax Arnold used. Carbon instead of mainly glass. Still with the ability to be under 300Kg and do FAI record attempts. The additional 45hp and a suitable airframe should allow some record bashing. The current holder is a effort from the a Brazilian university and is a wooden/glass/carbon airframe and a Jabiru 85hp. Set a heap of records and truly a worthy taker of the crown. I think the Ar-5 was really retired for history's sake- not from inherent problems. Arnold went on to create the AR-6. Something real special about a super-sports aircraft that weighs so little- physics of flight loves low weight. Even a slightly heavier and more user friendly stall speed wing version would be a awesome aircraft to fly. The Brazilians have really hit the target with being able to use a four stroke instead of the 2 stroke norm we see in this weight. I would prefer the Jabiru for reliability and economy plus the extra power over a rotax smoker anyday. The idea of a Simonini pumping 110 Italian Stallions does get the heart pumping though. A updated AR-5 is a very tempting idea, 250mph would get the adrenalin flowing and smash a record or more. Given that a 65hp rotax did 213mph, 250mph on 110hp is quite possible.
     
  6. Sep 5, 2011 #6

    andytk58

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    Thats good to know. I don't suppose you know how many hours the aircraft had when it was retired.

    The reason for asking is related to the construction method. It seems like an ideal method for a plans built lightweight two seater in a similar vein to the Vision, but smaller and lighter. However airframe life due to vibration on the styrofoam panels would be my concern. The AR-5 did look exceptionally well built though.

    Europe could really do with a simple plans built aircraft using mid time 2nd hand rotax 912 engines. The Vision isn't approved, and uses engines which are just too thirsty for Europe. Most aircraft are (expensive) vac-molded glass/carbon kits. Or you build in wood with an old VW conversion.

    Ah, but the AR-6 is produced using the regular mold-vac-carbon/epoxy method (I think). So its a completely different beast.

    Andy
     
  7. Sep 11, 2011 #7

    Bimini57

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    I had the Arnold AR-5 construction video many years ago and found it very informative. Your statement: "airframe life due to vibration on the styrofoam panels would be my concern" leads me to think that looking to the AR-6 (as litespeed eluded) is wise. The AR-6 was built for SOMEONE ELSE to fly, and presumably, for many years to come. Like the AR-5, it is also a beautiful plane.

    Steve Senegal Endeavor 11 N616DH Arnold AR-6 Reno Air Racer - YouTube
     
  8. Sep 11, 2011 #8

    litespeed

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    Orion might be able to answer..................... But I don't think there is anything inherently unsafe about the AR-5 and its construction. Just that it is a hotship as far as getting it off the ground and back. I think besides the history bit that the greatest concerns he ever had were engine wise. The construction methods used and the quality of work appear more than adequate. It was never made to do thousands of hrs in anyway. Phil
     
  9. Sep 11, 2011 #9

    litespeed

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    AS far as the vision is concerned- would not matter what approval it had or engine..................... I would not trust it. The principle appears sound but the materials used are not. That is just my view.........but it would be my ass in it, so no dice.
     
  10. Sep 11, 2011 #10

    orion

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    If I were to take a guess at the reason, it'd simply be that the AR-5 was designed strictly for one thing: Setting records. As such, the airplane is pretty much useless for anything else, it is small and cramped, has little to no range and it is most likely designed around very minimal margins so as to keep the weight down. As such, retirement was the only possible future since continued use could have compromised some part of the structure. The construction methods were most likely just fine but the actual structural integrity might have been below that needed for long, continued life.
     
  11. Sep 11, 2011 #11

    flyvulcan

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    240mph on 90hp

    It was reported (Sport Aviation magazine) that Johny Murphy was indicating 240mph in the prototype Lightning Bug (750 lbs take-off weight) using a 90hp AMW engine during the Sun100 air race where he suffered his engine failure, dead-sticked it into a paddock and hit a cow during the rollout. This has to be nearly as impressive as the AR5 and the Lightning Bug subsequently turned into a production kit.
     
  12. Sep 11, 2011 #12

    flyoz

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    Mike in his video's goes through his aircraft after he had an engine failure and forced landing
    The damage was very small and the airframe itself was in excellent condition - it proved the integrity of the construction method .
    I think ( as was suggested ) it was retired because it was simply a "one off specific design " and kept for posterity
    Most of Rutan's initial aircraft like the original Varieze were kept for the same reason
    Glass on styrene has proved to be not only resilient but very good at absorbing energy on impact
    Flyoz
     
  13. Sep 11, 2011 #13

    Will Aldridge

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    According to Mr Arnold he didn't set out to break records. He wanted his own mini dogfighter, that was stable and responsive. He could have cut down on wing area if he really wanted to go faster and he mentions something about aileron flutter limiting his top speed. I bet if he was really after records he could have addressed those issues. Mr Arnold although of average height has a very slight build and I don't think the cockpit was really cramped for him.

    One question I have always had about the design was why he went with rounded wing tips? He is a devotee of Hoerners Fluid Dynamic Drag, and I would have thought that he would have made a Hoerner wing tip. Instead he went with the worst possible design (according to Hoerner) with a large radius.
     
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  14. Sep 11, 2011 #14

    autoreply

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    Because wing-tip design and planform design (especially on the internet) is 99% old wives tales and 1% factual engineering.

    A simple rounded wingtip is just as good for induced drag as a Hoerner one if you design with the same constraints, hence almost every sailplane has one in the straight (non-winglet) version, and you won't find people who're more anal about induced drag. Most "results" focus on an elongation of the original wing, which isn't exactly apples to apples. Pretty sure that in frontal drag the rounded wingtip does even better, which is way more important for a fast ship.

    And last but not least, a simple rounded wingtip is a lot easier to produce.
     
  15. Sep 13, 2011 #15

    andytk58

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    I could probably fit in the AR-5 with room to spare, as I'm only 144lbs soaking wet. When I fly solo climb rates are fantastic:gig:.

    I'm still gutted they stopped making the Pulsar 582 as for me thats the all time affordable hi performance 2 seater sport plane, and there really isn't a replacement for it.

    I was aware that Mike Arnold never intended his aeroplane to be a record breaker, but more a mini-fighter, so I was surprised to hear it was laid up in a museum. If that'd been my plane you'd have had to take it off me by force.

    Andy
     
  16. Sep 29, 2011 #16

    MX304

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    I wish the Hiller Museum hadn't hung it from the ceiling. You can't get a close enough look at it to learn much.
     
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  17. Oct 10, 2015 #17

    Stealth

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    ... "I was aware that Mike Arnold never intended his aeroplane to be a record breaker, but more a mini-fighter, so I was surprised to hear it was laid up in a museum. If that'd been my plane you'd have had to take it off me by force."


    Most of his efforts seem to have been for Record Breaking. You don't put tiny engines into fighters. You don't make the surface the smoothest of any airplane on earth for a fighter.

    His initial reason was to keep up with RV's on the way to airport restaurants, but it's clear Record Breaking/Setting became a priority early and stayed the priority.

     
  18. Oct 11, 2015 #18

    Aesquire

    Aesquire

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    I was one of many that called Mr. Arnold when it went up for sale. I'm wider than Mike and didn't fit.

    It was retired to work on other projects. Still flew fine and within rational operating limits.

    The construction was plenty strong enough for gentlemen aerobatic use..... but like any clean design you didn't want to point downhill for long.

    No limitations on airframe life. Foam & glass is not a temporary technique. Better than rivets & sheet metal for corrosion, worse for ultraviolet.
     
  19. Oct 11, 2015 #19

    Aesquire

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    The Symmetry airplane built by a Scaled Composites employee shows the best practices use of the "Rutan" aka sailplane repair building technique.

    Careful attention to shape. One fairly thick layer of filler, nearly all sanded away, to perfect the profile and fill pinholes.

    Equals prize winning smoothness and speed.
     
  20. Oct 12, 2015 #20

    autoreply

    autoreply

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    This one. The informal son of the AR-5.
    http://www.homebuiltairplanes.com/f...hnology/6092-cory-birds-symmetry-details.html
     

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