luces en las alas

7/30/2019 Luces en Las Alas

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Introduction

In October, I inspected and bought aViking Dragonflybuilt byWalterTriplettand first flown in 1987. The late, Walter Born bought the plane and it

was hangered since 1993. In November, Itraileredit to Huntsville AL where Iamplanning to spend 12 to 18 months rebuildingto make it airworthy again.The critical paperwork starts with the aircraft, engine logs, and pilot'shandbook:

Aircraft Log(HAPIEngine Log)Pilot's Operating Handbook

N19WT performance measured in 1987 with HAPI 1835ccengine.Comments? Questions?These can be mailed to:[email protected].

Past and Current Project Log

Earlier, project logs by month:2012_02- wing disassembly, navigation lights,and planning;2012_01- work table, shed, paper work, and startingwing;2011_12- purchase, towing, and work-shed.

2012/02/29 - LED lense and 2-stroke risks

The Freshnel lenses arrived and preliminary testing suggests the 10W LEDwith 2.5" lense may meet the distance requirements for landing lights. I needto build a rapid prototype but it looks promising.

An EAA member posted a link to anEAA Webinar on 2-cycle engine failures.Given by the owners Rainbow Aviaton, this FBO has extensive experiencewith 2-cycle operations. His experience is that 'offloading' the prop load isassociated with the greatest risks of 2-cycle failure. In particular, heleocoptersare especially sensistive but aircraft with wide speed ranges like the 60-140mph range of the Dragonfly, are at risk. I need to review his experience andmitigate this risk.

It occurred to me that I may need to go test-flight, airport shopping when

N19WT is ready to go. The advantage is I can choose an airport optimized forflight testing and do all of the testing there . . . on vacation. Having a wider
http://hiwaay.net/~bzwilson/dragonfly/Bobs_Inspection.htmlhttp://hiwaay.net/~bzwilson/dragonfly/Bobs_Inspection.htmlhttp://hiwaay.net/~bzwilson/dragonfly/Bobs_Inspection.htmlhttp://hiwaay.net/~bzwilson/dragonfly/dragonfly.htmlhttp://hiwaay.net/~bzwilson/dragonfly/dragonfly.htmlhttp://hiwaay.net/~bzwilson/dragonfly/dragonfly.htmlhttp://hiwaay.net/~bzwilson/dragonfly/dragonfly.htmlhttp://hiwaay.net/~bzwilson/dragonfly/aircraft_carrier.htmlhttp://hiwaay.net/~bzwilson/dragonfly/aircraft_carrier.htmlhttp://hiwaay.net/~bzwilson/dragonfly/aircraft_carrier.htmlhttp://hiwaay.net/~bzwilson/dragonfly/AC-20_27gChecklist.xlshttp://hiwaay.net/~bzwilson/dragonfly/AC-20_27gChecklist.xlshttp://hiwaay.net/~bzwilson/dragonfly/AC-20_27gChecklist.xlshttp://hiwaay.net/~bzwilson/dragonfly/aircraft_log.htmlhttp://hiwaay.net/~bzwilson/dragonfly/aircraft_log.htmlhttp://hiwaay.net/~bzwilson/dragonfly/engine_log.htmlhttp://hiwaay.net/~bzwilson/dragonfly/engine_log.htmlhttp://hiwaay.net/~bzwilson/dragonfly/engine_log.htmlhttp://hiwaay.net/~bzwilson/dragonfly/handbook.htmlhttp://hiwaay.net/~bzwilson/dragonfly/handbook.htmlmailto:[email protected]:[email protected]:[email protected]://hiwaay.net/~bzwilson/dragonfly/2012_02.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2012_02.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2012_02.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2012_01.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2012_01.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2012_01.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2011_12.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2011_12.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2011_12.htmlhttp://www.youtube.com/watch?v=GaaLb-BzqT4http://www.youtube.com/watch?v=GaaLb-BzqT4http://www.youtube.com/watch?v=GaaLb-BzqT4http://www.youtube.com/watch?v=GaaLb-BzqT4http://hiwaay.net/~bzwilson/dragonfly/2011_12.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2012_01.htmlhttp://hiwaay.net/~bzwilson/dragonfly/2012_02.htmlmailto:[email protected]://hiwaay.net/~bzwilson/dragonfly/handbook.htmlhttp://hiwaay.net/~bzwilson/dragonfly/engine_log.htmlhttp://hiwaay.net/~bzwilson/dragonfly/aircraft_log.htmlhttp://hiwaay.net/~bzwilson/dragonfly/AC-20_27gChecklist.xlshttp://hiwaay.net/~bzwilson/dragonfly/aircraft_carrier.htmlhttp://hiwaay.net/~bzwilson/dragonfly/dragonfly.htmlhttp://hiwaay.net/~bzwilson/dragonfly/dragonfly.htmlhttp://hiwaay.net/~bzwilson/dragonfly/Bobs_Inspection.html


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range of airports means I'm less subject to local, high-demand, airportmanagement. I simply trailer N19WT to where everyone agrees would be anideal test flight airport. Then I commute on weekends, holidays and onvacation to fly-off the hours.

2012/02/27

The simple solution to the 110 degree cone is a hemisphere reflector beind thebulb:


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A quick, cardboard reflector and some measurements and we'll be ready to'cut metal.'

2012/02/26 - Connectors, tap-testing and parts order

Via eBay 251001426424, a "Wichitech Digitial Tap Hammer Aircraft Tool" isjoining my tool set. This Boeing developed tool measures impact delay andprovides relative, quantitative numbers to all but eliminate subjectiveevaluation of the tap-test results.

A really simple solution to the 110 degree, light cone is to make a hemisphereplaced behind the LED light to limit the rear, top, and bottom cone. There isno problem with covering it with a reflective film.


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Apparently Cessnas use Molex connectors so I've ordered a Saber connectorkit. This will build out the wing wiring and start the wiring rework.

There is a Utube video on tap testing what appears to be a large, compositepropeller. I suggested at Homebuiltairplanes.com, composite forum, that weneed some Utube/MPEGs showing tap testing finding a delamination,mapping it out, and repair.

My wing aileron bellcrank and tubes should be here next week. The parts arecoming together and the wing should be ready for reassembly if not nextweek, the first week of March.

There are two, stop-holes for cracks on the right, wing-tip plexiglass cover.Some suggest using an acetone-plexiglass mix to seal the cracks. There is also

a canopy repair method that 'builds up' a crack repair on a canopy but theseparts are significantly smaller. The stop-holes and cracks need to be sealed tominimize water invasion.

2012/02/25 - Color code, More weight and balance, navigation light,

Dragonfly list

Apparently there is no aircraft color code and N19WT was built using justwhite wire. But I need to rework the wing wiring and eventually theinstrument panel and engine. So I plan to use the following color code:

black - current return or signal ground, Wicksred - 12V power, Wicks blue - signal, Wicks

I can get Tefzel insulation, 150C, MIL-W-22759/16 from Wicks and probablysomething similar from Spruce. But in the meanwhile, I have built-in wiringin the wing, all white. So I'll use colored heat-shrink to "tag" the wire where itcomes to the connectors or device. In the case of the BA15S, the color code ofthe solder joint will determine the function of both wires regardless of theirexisting color (aka., car parts use black for 12V.)

Based upon partial fractions and the empty weight of N19WT:

694 lbs @56.84" :: N19WT 172.6 lbs @7.38" :: HAPI engine 521.4 lbs @75.66" :: airframe

This does not include the propeller which will be part of the finalconfiguration and analysis.

The original prop weight, 4.9 lbs, is included in the airframe weight andbalance. I only took out the HAPI engine so the prop will have to be taken


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from the airframe weight and balance. But for now, we don't have thealternate engine prop weights and momement. Then the new prop is selected,the final analysis will need to take out the original prop and add in the newone. But for estimating the amount of firewall-to-engine space, these numberswill be close enough.

Working on the weight and balance for each engine option it looks the spacebetween the firewall and engine mounting:

7.63" - HAPI 1835cc 9.31" - Hirth 3702 12.66" - Jabiru 21.86" - Hirth 3502 27.76" - HKS 700e

Although the Hirth 3502 provides the largest amount of space, trying to fit theradiator and duct around and in that space would be a challenge. An ideal usewould be the parachute recovery system. Note this analysis does not includethe propellers, just the engines.

Looking at the BSR/Magnum products:

Magnum 620- 14.2x9.5x12.2 38 lbs, 1367 lbs, 187 mph BSR 1350HS- 20x8.5x6 33 lbs (w/o rocket), 1350 lbs, 184 mph BSR 1350 - 16x10x6 29 lbs (w/o rocket), 1350 lbs, 138 mph

Mounted at the front and attached to the engine mount anchors, there wouldonly need to be rear runners or steel cables to attach to the wing bulkheads.

I reworked the wing tip mount:
http://www.magnumparachutes.com/products.htmhttp://www.magnumparachutes.com/products.htmhttp://brsparachutes.com/files/brsparachutes/files/BRS%206%20Specifications.pdfhttp://brsparachutes.com/files/brsparachutes/files/BRS%206%20Specifications.pdfhttp://brsparachutes.com/files/brsparachutes/files/BRS%206%20Specifications.pdfhttp://www.magnumparachutes.com/products.htm


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This is a stronger part with a better socket mount.

I tap tested the upper and lower wing surface and found the only 'hollow'sounds were the wing tips and sections behind the drag spar. All other areastested solid with the peak wing thickness to leading edge being especiallysolid.

Apparently I have been removed from the Yahoo Dragonfly list. Someonecalled my engine analysis "twisted" as if calling something "twisted" wasenough. I'm not used to having my work called false with no empirical factsand data . . . just labeling it "twisted." Life is too short for such nonsense.Worse, it came to a head in an EAA forum where I went to get two-cycleinformation and was 'followed' by the Dragonfly list member. Regardless, I'veadded an e-mail notice link and address for those who read these web pagesand have questions or comments.

2012/02/24 - Nav light weight

Comparing the original equipment and the new navigation light:


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4.4 oz - Grimes and plates, 1.15 A. 1.8 oz - LED and plate, 133 ma. 2.6 oz - Tandy strobe, 310-340 ma. both strobes

2012/02/23 - Engine weight and LEDs

The original engine without the Ellison and exhaust stacks came in:

172.6 lbs - engine 1.3 lbs - Ellison 7.0 lbs - exhaust stacks and carb heat box

The 10 W LEDs arrived 'OH BOY!' At 11V, 900 ma., each generates 1000lum. and terribly bright. Even a 9V battery throws a lot of light. I've orderedsome Freshnel lenses to see if they might work as landing lights. I would haveno problem with a solid light that illuminates the canard when taking off orlanding. However, I may need a low-drop, voltage regulator after I measurethe voltage drop on the wing tip wiring.


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The first wing tip, navigation light:


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I had the red LED handy but the green belongs on this tip. One problem is Icanabilized the BA-15S socket from some units bought at a surplus outlet.

These sockets were cheap enough but they hold the bulb further out thandesired. Part 23 limits the amount of red and green overlap so on-comingtraffic can tell if our orientation is right or left of their point of view. With toomuch overlap, the other pilot can not tell if we are coming straight at them orpointed to the right or left of their path.

I can't use this part as built. The single pop rivet is a little too flimsey for thissize socket and bulb but it allows checking the fit and spacing. However, nowI can measure the offset and fabricate a stand-off so the bulb will be on thewing-tip plane. Also, the unpolished aluminum part reflects enough.

2012/02/20 - Estate papers, open house

I received papers from the law office handling the estate of the late WaldoBorn that includes copies to the widow and the FAA. Dated February 14, itwas a nice Valentines Day present. It is up to the FAA now.

We had an open house for the chapter which included five adults and twokids. I asked the older child to move the propellers to the work table and putthe seat cushions in. Not only did the kids but two adults sat in the plane. Ialso loaned back issues ofContactto the newsletter editor. All in all, great

success because the members now see I have a serious project and sensibleapproach.

We had some discussion about the shoulder harness bolts, fiberglassed plates,and safety wire. There was speculation about 'nut plates' some skepticismabout the bolt-to-bolt head, safety wire pattern. We also discussed the 366 lbuseful load.

I found a small crack forming in the left, tip lense so I drilled a stop-hole witha Dremel tool. Then a second crack formed from the first, stop-crack hole! I

drilled a stop hole for that one too but it sure was disappointing. It is possible Imay have to fabricate a replacement.

I've gotten most of the caulk removed by using a flat, screw driver. I tried butfound the 'caulk remover' is not effective. Regardless, it looks better but for athin layer of mold around the rim.

The Wicks quote for the Dragonfly hardware came in $1,040.14 but it shows acredit card. I'll check the Visa balance on Tuesday and see if they'll take apersonal check. I had been using the Visa card while waiting for the debit card

to come in.


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I thought there were cold-gas, parachute recovery systems but Google didn'tfind them. Regardless, it looks like the options are:

Magnum 620- 1367 lbs, 187 mph, 37.4 lbs, 14.2x9.5x12.2 Magnum 501- 1050 lbs, 187 mph, 21.3 lbs, 14.2x9.5x7.9 BSR 1350HS- 1350 lbs, 184 mph, 33 lbs, 20x9.5x6 BSR 1050HS- 1050 lbs, 184 mph, 24 lbs, 12x1x6

2012/02/19 - Rapid prototype and ballistics parachute

I am replacing the 1987, Grimes navigation lights with LEDs and this meansfabricating a new set of wing-tip, aluminum plates. I used PowerPoint to makean initial sketch but by the time I got to the work shed, I had a better design inmind. So I used a piece of shirt cardboard to fabricate a

template:

Notice there was an early cutout.
http://www.magnumparachutes.com/products.htmhttp://www.magnumparachutes.com/products.htmhttp://www.magnumparachutes.com/products.htmhttp://www.magnumparachutes.com/products.htmhttp://brsparachutes.com/sport_aircraft.aspxhttp://brsparachutes.com/sport_aircraft.aspxhttp://brsparachutes.com/sport_aircraft.aspxhttp://brsparachutes.com/sport_aircraft.aspxhttp://brsparachutes.com/sport_aircraft.aspxhttp://brsparachutes.com/sport_aircraft.aspxhttp://www.magnumparachutes.com/products.htmhttp://www.magnumparachutes.com/products.htm


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The first version had a problem as I'd trimmed too much off of the top:

It was easy to toss the first one and make a second one that fit.

So looking at both aspects, the cardboard prototype provides a template tofabricate the aluminum part:


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I've already used the cardboard template to fabricate two aluminum pieces, theleft and right wing tips. Using the PowerPoint sketch, I can now cut the sockethole and mount it to meet the Part 23 requirements.


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I still have to fabricate upper and lower light shields to meet the 110 degreelight cone and add the reflecting sheet. Then I'll have to drill the mountingaccess; install the aircraft grade nutplates, and; assemble the tips. I have all ofthe old parts and will be able to weigh and old and new parts. Then I'll put theGrimes units for sale.

I also disassembled and inspected the right aileron:

I am still waiting on the replacement parts.

The ballistics parachute needs mounting points so I'm thinking:


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two straps around the wing

There is a gap on the outside of each attachment point. The straps canrun around the front of the wing near the bolts that hold the shoulderstrap anchors:

The parachute straps can run between the shoulder strap anchors and

the lift attachment points.


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one kelvar wrap around the canard:

This kelvar belt will fit between the lift and drag attachment points andattach to a pair of parachute webs via "D" ring fittings attached oneither side of the center console. It makes sense to move the center stickto the left side which complements the plan to have center consolemounted engine controls. The canard attachment, parachute websfollow the space between seats and exit back to the rear bulkheadopening:


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A fitting or strap can hold the web straps behind the bulkhead centerbeam so there would be no risk of invading the pilot or passengerspace.

Testing the ballistics parachute would start with a static test where the aircraftis suspended by the parachute straps. The test requirements will be loadsharing between the straps and a 'wing low' descent attitude.

There are two rocket styles, pyrotechnique and cold-gas. Testing either oneposses a risk to the pilot and passenger as well as the fuselage. One possibilityis to mount the rocket launcher in a sacrifical fuselage. Then with camerasrunning, do a live fire with a dummy, parachute load and over-pressure andblast detectors for the pilot and passenger. With a cold-gas rocket, the plannedstorage pockets will be enough. If we go with a pyrotechnique rocket, a fireshield will be needed and tested.

The last thing is to fabricate a quick release mechanism for the wing cover and

test the firing lanyard. This does not have to launch the rocket.

2012/02/18 - Engine choices

There are three serious options:

138 lbs -2200cc Jabiru, 85 hp, 63 hp, 4 gal/hr @75% 118 lbs* -625cc, Hirth 3502, 60 hp, 3.9 gal/hr @5000 rpm, 4.7 gal/hr

@5,750 rpm 108 lbs -680cc, HKS-700E, 60 hp, 4.2 gal/hr @6200 rpm (3 min)
http://www.jabirupacific.com/specs/2200.htmhttp://www.jabirupacific.com/specs/2200.htmhttp://www.jabirupacific.com/specs/2200.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.bushwhackerair.com/hksspecs.htmlhttp://www.bushwhackerair.com/hksspecs.htmlhttp://www.bushwhackerair.com/hksspecs.htmlhttp://www.bushwhackerair.com/hksspecs.htmlhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.jabirupacific.com/specs/2200.htm


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The next level of analysis will be to look at secondary aspects of each engine.For example, complexity, TBO, available excess power and modeling withN19WT in X-plane. The HKS has a 3 minute, time limited, 60 hp modewhereas both the Jibiru and Hirth have no time limit on 60 hp operation.

An interesting EAA article ontwo-cycle engines

2012/02/16 - Engine choices

Which engine would you choose? Why?

Added the Rotex 582 which fails the range requirement.

2012/02/15 - Engine planning

These are some engines that have flown on other Dragonfly and spec validcandidates:

225 lbs -2700cc Corvair, 90 hp, 67hp, 5.6 gal/hr @75% 199 lbs -3290cc O-200, 100 hp, 6.3 gal/hr 176 lbs -1800cc, Subaru, 115 hp, 4.1 gal/hr

170 lbs -2331cc Revmaster, 80 hp, ? gal/hr

163 lbs -1835cc, VW, 65 hp, Great Plains, 3.5(?) gal/hr
http://www.eaa.org/lightplaneworld/qa/engines.asphttp://www.eaa.org/lightplaneworld/qa/engines.asphttp://www.eaa.org/lightplaneworld/qa/engines.asphttp://www.flycorvair.com/corvair.html#Engine%20Specshttp://www.flycorvair.com/corvair.html#Engine%20Specshttp://www.flycorvair.com/corvair.html#Engine%20Specshttp://www.zenithair.com/kit-data/zac-o-200-d.htmlhttp://www.zenithair.com/kit-data/zac-o-200-d.htmlhttp://www.zenithair.com/kit-data/zac-o-200-d.htmlhttp://www.ramengines.com/id63.htmlhttp://www.ramengines.com/id63.htmlhttp://www.ramengines.com/id63.htmlhttp://www.revmasteraviation.com/http://www.revmasteraviation.com/http://www.revmasteraviation.com/http://www.greatplainsas.com/specsfd.htmlhttp://www.greatplainsas.com/specsfd.htmlhttp://www.greatplainsas.com/specsfd.htmlhttp://www.greatplainsas.com/specsfd.htmlhttp://www.revmasteraviation.com/http://www.ramengines.com/id63.htmlhttp://www.zenithair.com/kit-data/zac-o-200-d.htmlhttp://www.flycorvair.com/corvair.html#Engine%20Specshttp://www.eaa.org/lightplaneworld/qa/engines.asp


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152 lbs -1835cc, VW, HAPI, 60 hp, 3.5 gal/hr 147 lbs* -939cc, Hirth 3702, 60 hp, 3.9 gal/hr @4,000 rpm-84 hp, 6.2

gal/hr @5,000 rpm 138 lbs -2200cc Jabiru, 85 hp, 63 hp, 4 gal/hr @75% 118 lbs* -625cc, Hirth 3502, 60 hp, 3.9 gal/hr @5000 rpm, 4.7 gal/hr

@5,750 rpm _98 lbs -625cc, Hirth 3203, 65 hp, 6.5 gal/hr @6,300 rpm

* Includes 20 lbs estimate for radiator and coolant.

2012/02/14 - Firewall planning
http://www.oshkosh365.org/saarchive/eaa_articles/1979_02_13.pdfhttp://www.oshkosh365.org/saarchive/eaa_articles/1979_02_13.pdfhttp://www.oshkosh365.org/saarchive/eaa_articles/1979_02_13.pdfhttp://www.recpower.com/3702%20-%203%20cylinder%20-%202%20cycle.htmhttp://www.recpower.com/3702%20-%203%20cylinder%20-%202%20cycle.htmhttp://www.recpower.com/3702%20-%203%20cylinder%20-%202%20cycle.htmhttp://www.recpower.com/3702%20-%203%20cylinder%20-%202%20cycle.htmhttp://www.jabirupacific.com/specs/2200.htmhttp://www.jabirupacific.com/specs/2200.htmhttp://www.jabirupacific.com/specs/2200.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3203%202%20cycle%2065hp.htmhttp://www.recpower.com/3203%202%20cycle%2065hp.htmhttp://www.recpower.com/3203%202%20cycle%2065hp.htmhttp://www.recpower.com/3203%202%20cycle%2065hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.recpower.com/3502%20water%20cooled%202%20cycle%2060hp.htmhttp://www.jabirupacific.com/specs/2200.htmhttp://www.recpower.com/3702%20-%203%20cylinder%20-%202%20cycle.htmhttp://www.recpower.com/3702%20-%203%20cylinder%20-%202%20cycle.htmhttp://www.oshkosh365.org/saarchive/eaa_articles/1979_02_13.pdf


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Only reducing weight increases payload so here are some reported engineweights:

_98 lbs - 60 hp, two-cycle, Hirth 3502, w/o radiator 163 lbs - 1835 cc, Great Plains w starter 170 lbs - A65, Wiki report w/o starter 170 lbs - O-200, Wiki report w/o starter

2012/02/13 - FAA on flight testing, Contact Review

I sent a note to the FSDO about flight testing and got the following reply:


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Hi Mr. Wilson,

The FAA Form 8130-6 is an application for, or amendments to

airworthiness

certificates, like an engine model change would require an amendment

to the

8130-6 and Operating limitations giving you additional flight testingtime

of 25 hours on the new Operating Limitations and this would require me

to

inspect your aircraft prior to issuance.

Thanks,

George B. Castleberry

Principal Maintenance Inspector GA/AW

Alabama/Northwest Florida FSDO

1500 Urban Center Drive Suite 250

Vestavia Hills, AL 35242

Phone: 205-876-1352

Fax: 205-876-1358

From: bwilson4web

To: George B Castleberry/ASO/FAA@FAA

Date: 02/03/2012 09:26 AM

Subject: About engines for N19WT [Re: Follow-up on N19WT phone

call]

Hi George,

My A&P, Harold, came out to the work shed Thursday evening

and inspected my setup and a preliminary review of N19WT. Harold asked

if we used a certified engine, say an A-65, instead of the per-design,

1835 cc VW engine, would that eliminate or change the number of hours

needed to fly off the Form 8130-6?

Harold suggested that since the airframe had already gone through the

initial, restricted flight program and has 150 hours, would use of a

certified engine in this amateur built, N19WT, eliminate or modify the

restricted flight testing?

Also, Harold confirmed the firewall engine mount points are 'out of

round' and suggested a repair approach. I want to do my own stress

analysis but I was wondering, is reviewing a critical repair something

your office does for amateur built airplanes?

I have an abundance of caution about some things and engines and

engine mounts is one of them. I have no problem (and appreciate) when

experts are able to render an opinion. But it will take me a couple of

weeks to complete my stress analysis and assemble a package.

Neither of these are pressing problems as I don't anticipate getting

to the final engine and engine mount decisions until late spring,

May-June, at the earliest. We still have a list of things to inspect,

fix, and document in the rest of the airframe.

Nearly two weeks ago, I sent the widow of the previous owner the FAA

forms I had gotten from OKC along with a stamped envelope to forward

her 'power of attorney' information. With any luck, I'll be theregistered owner of N19WT the end of February or mid-March. In the


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meanwhile, I have the 'pink' form 8050-1 with the aircraft log in my

newly started "Aircraft Maintenance Book: N19WT".

As always, if you are in the Huntsville area and have time, let me

know. I'd love to show you my work shed and N19WT.

Thanks,Bob Wilson

256-961-9391

I also got a note from another Dragonfly owner that any changes to thepowerplant including a propeller change have to be 'flown off.' He reported 10hours which makes sense for a propeller change. An engine change would andshould be longer if nothing else than to confirm the flight characteristics andweight and balance. Good, fast, cheap, pick two: I choose GOOD everytime.

I finished reading all issues of _Contact_ magazine and learned some valuablelessons:

Torsional vibration is often poorly understood but literally blew-up theBD-5 development. The ultimate fix was a free-wheeling clutch soexcess inertia from the prop can not feed back into the engine. Such asimple solution, light yet effective, it aleviates any need for energyabsorbing couplings. The prop expends its excess energy in pulling theplane forward and the next engine power pulse catches up.

P-51 cooling was radically efficent because the air was significantlyslowed down before reaching the radiator. A British study gave the

North American engineers a clue and they used it. The scoop below thefuselage does not show that twice that distance is taken up in thefuselage with the radiator. Smooth ducting allows the air to slow-downand pickup the heat at low velocities. This improves radiator efficiencyas there is more time to warm the air. Then the air smoothly acceleratesout the rear by the taper. An automatic, gate relieved the pilot ofanother cockpit chore. As for sizing the radiator, find a light-weight,efficient automotive radiator sized for the equivalent engine power. Forexample, if I choose to use a 60 hp, water cooled Hirth 3502, I wouldlook at the 1.5L and 1.8L Prius radiators. Since these radiators also

include a second loop for air conditioning, it can be used to increase theeffective cooling by running it in parallel with the coolant loop.

Augmented exhaust has been used to provide ground, cooling air flow.There are probably NASA/NCAA design articles and this bears furtherinvestigation. In an ideal world, an exhaust augmentation tube canprovide not only airflow for ground cooling butmightprovideadditional thrust if the excess heat can mix and expand the cool air.

Stock, automotive fuel and electrical systems often have a poorlydocumented, "safe home" mode that engine power levels can trigger. It

is better to go with an aftermarket, fuel injection and ignition systemthat does not include such 'safe home' modes.


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The stock, Corvair crankshaft, even with bigger bearings, still hasissues with fractures in flight. This could be an undiagnosed, torsionalvibration issue or just the fact that autograde crankshafts should betreated as an unreliable part.

Successful O-200 installations use aftermarket, SDS, electronic fueland ignition systems. The strong, aircraft grade case, crank, andmechanical parts are married with high efficiency fuel and spark.However, the fuel consumption and weight still remains a problem.

Proper use of an aftermarket, EFI system means redunancy in the newtechnology:

o dual, independent power - must have capacity 2x fuel durationo dual, independent controllers - run either/or mode, possibly both

during takeoffo dual, primary sensors - cam shaft/crank sensors split for each

controllero dual, sparkplugs - if head supports them without residing in oil

batho dual, fuel pumps and filters - run either/or mode, possibly both

during takeoffo dual, fuel injectors - run either/or mode, without O{2} sensors,

OR mode

Designing redundancy and fail-safe modes, flight power, limp-homemode, is not a trivial problem. But it is a lot easier to handle the design

and testing before building and flying.

I am seeing a lot of engine failures that 'smell' of torsional vibration issues.That something is hard to measure does not mean it doesn't exist. But now Iunderstand the "torque limiter" found in the four-cylinder Toyota Priusengines.

The torque limiter is just a clutch-plate, bolted on to the flywheel. It can wearWHEN the engine and transmission get into a speed and power range that hastorsional vibration resonance. In these cases, the clutch plate simply 'slips'limiting the feedback, the amplitude of the torsional resonance. Such assimple solution and so few understand it. From an efficiency standpoint, afree-wheeling clutch is a better solution.

2012/02/09 - Lights, Engine mount repair, and parachute

I have ordered some reflective sheeting and figured out my wing navigationlight design. I've bought two, BA-15S sockets and will cut out two, newmount, aluminum sheets. The sockets will be mounted as high as the lip of the

wing tip so the LED is fully exposed forward and to 110 degress off of thewing tip. The back-side and mount plate will be fully reflective so all light is


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projected outward in the 110 degree arc. There may be an issue with upperand lower projections that may exceed the 110 degree plane to the rear but IFthat becomes an issue, a simple light shield inside the plastic cover can solveit.

Dragonfly N19WT has 150 hours on the Hobbs meter. We took the engine offincluding the mounts and preliminary examination shows the firewall, enginemount holes are out-of-round:


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I plan to clean the angle aluminum and dye test for cracks. If I find cracks orother defects such as evidence of corrosion at the firewall, we'll fabricate anew firewall-based, engine mount, one that adds aluminum plates and interiorfiberglass but this adds weight. So we have a workaround IF we can not re-

work the original mount.

My A&P and I discussed the out-of-round holes which are a problem for theengine mount. We are thinking:

overside drill the holes insert an identically thick aluminum disk (same aluminum type as the

mount) with an interference fit (aka., heat the anchors and dry-ice/nitrogen freeze the insert disk.)

rivet identically thick, aluminum plate to outside of the two "L"surfaces

drill engine mount holes per original spec but use the incrementalmethod to size the hole exactly for the AN mount bolt

This would be a lighter weight repair than the fall-back, engine mount but I'munder the impression that rivets require some number, a pattern over an area,and require the rivet material to match the same type of aluminum in the plateand original anchor. We can't have different thermal expansion rates work-harden or loosen the repair over time. However, the insert has me bothered.

Even with a perfectly sized insert, there would be no tension strength, onlycompression strength. This is aluminum which means it tends to plastic flow,


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to stretch over time. Due to the foam-and-fiberglass construction on the otherside of the firewall, aluminum welding would be a big challenge. There arealuminum, cold-welding techniques but those are computer controlled, fixedpiece welds, not an ad hoc, method.

The only repair to the original anchor mounts is to do a stress analysis of theoriginal part with the original sized holes. Determine the maximum stress theycan support and the strain as a function of loads. This means for the originalHAPI engine and prop, what is the load at which the part deforms and the loadat which it fails.

Now do the same analysis with the next, oversized holes. This also means theengine mount will have to be rebuilt using larger diameter, 4031 tube at theanchors. However, the four, oversized tubes will more than handle the engine

stress and strain . . . if the firewall anchors will.

I've read the first 50+, back issues ofContactwith about 80 more to go. So far,my take-away:

Subaru's are popular - the best approach appears to be getting a fuel-injected, Subaru using the vehicle engine electronics.

Goldwing - way too heavy in the one report. Retro-fit fuel injection is not a trivial or cheap solution. Single-point exhaust into an augmenter, one example, seems workable. Radiator design for water cooled engines is a non-trivial design

problem. See P-51 article on cooling drag.

It turns out that a 1,050 lb, ballistic recovery chute costs ~$5,000 and addsabout 30 lbs to the gross weight. The advantage is:

Safer night flights Opens the engine options including two-cycle engines

My first choice remains an 1835 cc, Great Plains engine since it matches Bob

Walter's original design goals. However, there sure are a lot of folks whoadvocate other engines ranging from A-65, O-200, Subaru, Corvair . . .Adding the ballistic chute means we can 'reliability' gets a reduced valuationwhen the final engine selection is made. We can look at engines from a pureperformance standpoint.

2012/02/04 - FAA light requirements

23.1385 Position light system installation. N,17,43

23.1387 Position light system dihedral angles. N,12,43

23.1389 Position light distribution and intensities. N,43

23.1391 Minimum intensities in the horizontal plane of position

lights. N,43


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23.1393 Minimum intensities in any vertical plane of position lights. N,43

23.1395 Maximum intensities in overlapping beams of position lights.

N,43

23.1397 Color specifications. N,11

23.1399 Riding light. N

23.1401 Anticollision light system. N,11,20,49

2012/02/03 - A&P survey, parts and tools

I really need to add at least one strong, drop light to work on the fuselaage.Also, I need a better plan to overlap material delays for parts and work.Harold, my A&P, came out and gave me a lot of help:

out of round engine mount holes - he saw it immediateately and wediscussed options. For example, another aluminum plate rivited to thefirst; drill out the hole and put in a bushing; and drill the bushing to fit.

This is such a critical part, doing a full stress analysis makes sense butit sounds feasable. From the web is a suggestion to use loctite whenseating the bushing. Certainly from a strength of materials and thermalexspansion view, this makes a lot of sense. Best of all, less weight thanthe alternative engine mount.

fuselage forward hatch - well received. It will take planning but weboth agree this makes sense.

rudder pedal relocation - we discussed the options and I have to dosome measurements to find out if canard forward works. Also, we'llmeasure the diameter of the brake cylinders and replace the rubberparts.

wing left drag bulkhead nutplate - OK wing bellcrank part inspected and the nut on the bad one has too little

thread showing working relationship - I will disassemble, inspect but only together will

we reassemble the parts so he sees or does 'hands on' what needs to bedone.

reviewed paperwork and the Aircraft Maintenance Log withdescrepancy forms.

FAA Part 43, 12 recommended to address electrical connectors discussed options on circuit breaker panel and panel changes: replace

NAV/COM with Comm, GPS, and Mode-C. Also replacement of theELT.

need to ask FSDO if use of a certified engine instead of a VW makes achange in the flight restriction fly-off.

The wing electrical work will remove the strobes and safety the wire endsusing heat-shrink. I need to find a reflector to cover the former strobe mount.However, we will put red and black heat-shrink to identify each wire at the

wing root and tip.


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We need to check the FARS on navigation light viewing angle. The A&Pthinks they need to be seen to the rear but the the Sport Aviation articleclaimed they need a 140 degree view with a forward line of sight. We'll getthe FAA guidance and comply.

We both see the navigation light connectors, spade lugs in heat-shrink, as thewrong solution. The A&P recommended getting an aviation grade, connectorand I agree.

I've ordered a 1/4", aircraft grade, torque wrench which should be here aboutthe time the parts arrive. We'll see what the calibration looks like.

2012/02/01 - Navigation light and parts

The LED navigation light eleminates the lens, the flairing, and replaces thebulb:


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1.15A - original bulb current 0.133A - LED current

The strobes work although they are soldered into Radio Shack units. I wonderwhat temperature range the caps are rated for and power transistor. Sad to say,the electronics were not anchored and the reflector had only one screwholding it in.

0.310A - minimum, dual-flasher current 0.341A - maximum, dual-flasher current

The nuts holding the engine rubber bushings were loose but cotter pins heldthem in place.


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Here are some preliminary photos of the rear fuselage:


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Removed the wing cover to survey the mount. Also measured width of canardand wing attachment points to understand the area blanked out:

43.55 ft. sq. - canard lift area 8.81 ft. sq. - canard fuselage area 40.73 ft. sq. - wing lift area 7.24 ft. sq. - wing fuselage area ~100.33 ft. sq. - total wing and canard area

So how much lift does the fuselage generate over the canard and wing?

1 each ALB-1 Aileron Bellcrank $90.00

1 each 4130 1/2" x 0.049 x 7 3/4" $3.78

8 each MS21042-L3 Nut $3.20

4 each AN3-10A Bolt $1.00

4 each AN3-13A Bolt $1.20

8 each AN960-10 Washer $2.00

Shipping $10.00

Total $111.18

Richard KaczmarekFast Little Airplanes


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2232 North State Route 559

Woodstock, OH 43084

937-243-7303

[email protected]

Increased the tube count to replace both sides.

I still don't have a good model of what I can and can not do to N19WT. Anamateur built plane can be modified by the owner but maintenance must bedone by an A&P. Regardless, I have no problem with the A&P being hands-on with N19WT . . . I spent nearly 40 years learning and practicing computerand network skills, not haning at the airport and learning how to handleaircraft. It is 'career shortening' to ignore experts.

luces en las alas

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