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jlknolla

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I may have come across a Glasair I TD project that is too good to pass up and am curious if any HBA members have experience with assembly of the first generation Glasair aircraft? Looking for tips and tricks, suggestions and modifications to consider in my evaluation/planning.

Still need to do a full inventory but looks like a good candidate project.

Thanks for any info!
 

orion

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I worked with Glasair back in the mid eighties. The IIS, the Super IIs, the slotted flaps, along with a couple of other things, are my work. If you have specific question I'll try to give you some direction if I can.
 

Tom Nalevanko

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I have a friend at KCMA who built this type and has been flying it for years. But he perpetually keeps re-building it... I can put you in email contact with Ray, a Brit ex-pat. And we are just up the coast, a long swim but a short flight...

Blue skies,

Tom
 

jlknolla

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Thanks Orion and Tom.

A local chapter buddy has a reportedly complete Glasair I TD kit (about 50-60% completed by my estimate) and an IO-320-B1A (160hp Twin Comanche engine) as a package deal - after my recent Glasair I RG flight, I might be willing to build instead of buy if it gets me more overall capability per dollar (build a Glasair I TD instead of buying a flying T-18).

Is that a Stallion in your avatar Tom? I saw one in a hangar at Golden State fly-in a couple years ago.

I will probably join Glasair.org and pick some brains over there but figured I'd check here as well. A co-worker was at Stoddard-Hamilton for several years right up to the bankruptcy and recalls a lot of the modifications that were completed for the II and III as well as some projects that were in work - so I have some help there too - he currently flies a Glastar he built.
 

jlknolla

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Orion, couple questions for you:

Is it possible to retrofit the slotted flaps to the G1 wing?

The flat-bottomed (decambered) ailerons from the G2 would overcome what I felt to be slightly heavy ailerons right?

Do you know if the G1 suffers from the same black holes of drag at the WTB intersection as the GIII? Ideas on cleaning it up?

For the G1 wing, is there any real benefit from an upturned Hoerner tip? I am thinking of going with a combined LED ACL/Strobe and Tail Light (AVEO 3-in-1 kit from AS&S) on the wingtip and not sure if the 3-in-1 can be added to the Hoerner in a low-drag style and meet tail light visibility requirements.

IF I do this, I am thinking to build it as clean (internal antennae) and light (EFIS, SKYTEC Alt and Starter, etc.) as possible. Also planning to examine Kent Paser's Speed with Economy for potential mod's understanding each mod adds time and completion risk.

Are there any 3-blade props that fit the IO-320-B1A which are high-speed props? Looking for acceleration, climb and power-off drag over maximum top speed from a 2-blade.

Thanks again
 

orion

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1) Yes - the slotted flaps can be retrofitted to the G1 wing. That is how the system was designed - so that it could be adapted to the original kit configurations. The wing kits weren't modified for the slotted flaps to be standard until some time after the flaps were in production as an option. It is a little bit of work since the upper skin has to be extended and the flap hinge mountings need to be internally reinforced, but it has been done on quite a few kits.

2) Yes - the decambered ailerons go a long way to diminishing stick forces.

3) The "I" through the "III" wings are petty identical - the only change is the laminate schedule. For a long time they actually came from the same tooling. The wing to body geometry is identical across all the models. But while there is a bit of drag due to the acute angle there, it is not nearly as significant as some make it out to be. A small, reasonable fillet in the area can go a long way to improving the flow but the benefit on many has proven to be nearly immeasurable. Some of the racing configurations have demonstrated benefit (along with a filet extension at the TE) but it's of course up to you whether the benefit vs. the amount of work is really worth it.

4) The wing tips were done in this manner more for aesthetic purposes than functional ones. There was never any real evidence (that I've been able to track down) that clearly demonstrated the benefits of that tip versus another.

5) Don't have any recommendations of prop for you. Many different variations have been tried of course but the only ones that at least seem to deliver improved performance are those from MT. Don't however have any data on this outside of owner comments. The MT props also are said to be quieter and less prone to induce vibrations into the cabin.
 

jlknolla

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Thanks again Orion. Do you still have your design notes for the original slotted flap for the GI?

I coincidentally just found your writeup from '07 that discussed the results from your original single-slotted design to the productionized flat bottom version that became standard (12 mph vs 8 mph reduction), and would not be afraid to build a flap, IF I do go into this project.

While the ailerons do need to be decambered (in my opinion) to improve stick harmony, the camber on the flap section is just fine by me - this is an area where I suspect physics trumps aesthetics - who cares if the flap and aileron section are not visually identical underneath the wing if the plane slows down nice and good and has harmonized stick forces.

As a data point, the Glasair I RG I flew recently appeared to have the plain flaps, and we were doing slow flight at around 70 KIAS flaps down if I recall correctly - it had a very pronounced buffet (tail shudder really I suspect) thanks to trip strips on the inboard wing LE - does that sound like the plain flap to you? If so, I could actually live with the plain flaps since it seemed to slow down OK, I think we probably touched down at maybe 60-65 KIAS - but slower is always better if doesn't have a corresponding hit on the high end.

I have a series of questions in to GlasairAviation about possibly buying upgrade parts but understand the flap kit is likely near $4K - do you think your original setup could be produced, one-off, including the machined hinges for the same or less?
 

orion

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No, I do not have the Glasair data - that was developed and therefore kept by the company. But returning the under-camber back to the flap and flattening the ailerons' bottoms was the customer's GIII configuration, which apparently worked very well.

It's been a while since I've flown a G1 - being 6'4" tall and about 240 pounds the G1 was simply a shoehorn and a gallon of goose grease sort of fit. It was sort of OK once I slithered in but the person next to me better be a really good friend. I always thought the G1 would have made a nice single place.

The flap could probably be reproduced for that cost but only if you got some of the original design drawings and of course did all the fabrication work. The prototype on the GIII was built by the plane's owner, using the plain flaps as a geometric starting point. If I had to redo the design work on a one-off basis for you, there would of course be a charge which would bite into that budget.
 

jlknolla

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Matches up with my expectations Orion, thanks. I need to spend some time reviewing the actual build, logs and manuals as well as an inventory. Since the slotted flaps can be fitted (according to the Glasair website) it probably makes sense to do it during the inital build. Appreciate the info!
 

orion

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Yes I do, especially in a kit this old. The critical part of the inspection he's going to have to go through is to examine each and every sandwich panel within the structure in order to determine how much delamination, if any, has taken place over the years. Kits that have been around this long and have not been built often go through several moves and each one can introduce hangar rash that could compromise the laminate in some way or another. I might recommend even going so far as to remove small cores from the structure and examine the laminate and the adhesion to the core foam itself - it's the only way he's going to know for sure that the structure is still viable after all these years.

Another thing to take a close look at is the wing panels - these were often pulled from the factory mold when barely green cured. The skins were then placed flat on shelves so after time, as the resin continued to cure, the geometry had a tendency to flatten out. If the skin has not been properly stored, the current shape of the wing skin may not be even close to the original airfoil shape. Forcing it back to shape is nearly impossible so the airplane he builds may not be even close to performance or trim of the original.

In short, there's a lot of things to look at here that are well beyond just the simple quality of the build done by the previous owner.
 

jlknolla

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Good info guys - thanks.

Since this has only been offered to me within the past week, I am not sure the kit number or exact age yet, nor when the current build status was achieved - obviously the G1 was replaced by the G2 in '86 or so if I recall correctly, so it is probably at least 25 yrs old.

I plan to review paperwork, logs and manuals first to get some sense of the history of the project, number of owners and moves, environment it has been in, etc.

My intent when I get around to physically examining the kit (current owner is in Reno for the races) is to check panel integrity (knock test) all over the fuse, empennage and wing, check for obvious voids/delams visually on all interior panels (exterior is white, not sure if Glasair was gelcoating or not but I think they were). I was planning to check empennage and wing skins for correct shape to whatever extent possible including section and twist (form boards would be best but not sure how that could be accomplished). This will also be when I look for quality of build/assembly.

I had not considered actually going as far as core samples unless there was a reason to suspect a particular panel. I do know that Glasair had recommended some suggested strength mod's for the G1 based on improvements in the G2 and subsequent kits - I plan to look for those and would incorporate them if not already present - IF I were to take the project on.

Assuming the paperwork and physical inspection looks good, and after a full inventory, then I may get into negotiation.

I am in no hurry on this, hadn't actually considered building/completing a kit until I was approached about this project - I was more interested in buying an affordable completed and flying aircraft like a Thorp, and then slowly designing my own from scratch.

The price discussed for this project and the IO-320-B1A make the possiblity of Glasair performance for Thorp costs possible, which is very attractive - while also giving me some direct insight into construction/assembly for when I complete the design on my own concept. Also some opportunity for experimentation/modification. Could be a win-win for me.

Any other advice for when I spend time checking the project out?
 

AirSharkII

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Orion, the early Glasair kits used Last-a-foam for core material, right?. Are you suggesting that with analysis of core samples that LF can be used safely or should LF not be used no how no way? I ask because my AirShark project, I believe, uses Last-a-Foam as well. Once design and structural analysis is complete, we'll need to test core samples or build new parts with an alternate core material. Thanks.
 

orion

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Some time ago I mentioned that I was asked to research and do a bit of testing of core materials and recommend airframe suitable products. It was in this report that I reported on the applicable materials and that it was my recommendation that the LaF not be used in any flight structure. The report was written for Glasair shortly after it was discovered that certain components were getting delaminated and/or the core was breaking up. The company read through the report and subsequently deleted all copies, including the backups on my computer. They stayed with LaF primarily due to cost.

Personally and professionally I would recommend against the use of LaF in any flight structure. With some surface prep it may be suitable for less structural applications or in the higher densities, it can serve as a filler such as in sandwich tapers. But personally I would stay away from it regardless of the application.
 

jlknolla

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Orion thanks again for sharing your experience and thoughts on this.

I do have a question about your concerns for LaF if you will continue to indulge me.

Obviously there are a couple thousand Glasairs of varying stripes and build qualities flying, some for more than 20 years, and there are other aircraft using LaF cores including much more modern designs (e.g., Vision) - I think I have only heard of one structural failure for the Glasair as a family (a horizontal stab failure if I recall correctly – although Glasair claims there have been no structural failures).

In the absence of contrary evidence, I would typically chalk up failures or issues like these on homebuilts, at least ones as popular/successful, and presumably as well designed as the Glasairs, to assembly error (omitted layup) or poor quality (dry layup, voids, not washing hands after eating fried chicken, etc.). I mean, these are aircraft which are clearly presented as capable of +9/-6 G Ultimate, +6/-4 Limit loads, and I remember watching Bob Herendeen fly the stuffing out of his GIII back in the day.

Did you find that the core degrades over time to such a point that eventually it no longer can effectively separate the skins from a sandwich/structural standpoint? What is the failure/degradation? Do you believe that these type sandwich panels will eventually not be airworthy and we will start to see structural failures as the fleet ages?

Is the Glasair designed in compliance with your thoughts on not having the core material at hard points and interfaces? To your knowledge, was the quality control and prep during fabrication at Glasair in those early days solid enough to address your concerns? I assume so, but haven’t really examined one before closing to know.

If I were to take on this Glasair project I would certainly intend to fly it hard occasionally and to do that I need to not have any little gremlins running around in the back of my head questioning the structural integrity of the beast. My impression of the design and assembly of several kitplanes, including the Glasair, is that they were designed to accommodate a certain amount of stupid builder tricks and still be reasonably strong and safe aircraft – am I assuming too much here?

Is your concern so significant that you would not knowingly fly in an aircraft with LaF cores, or is it more that you would not choose it for any project you worked on? I am not trying to be argumentative here, just want to understand your concerns better. I would be putting myself, my wife, our daughter, and friends and family in this plane if I do this.

Thanks again for your time on this, I really appreciate it.
 

jlknolla

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Thanks autoreply, the Personal Cruiser/LaF thread was a great thread with good insight all around. Oddly, it did not come up when I searched on last-a-foam after Orion and AirsharkII made their initial comments, must have been case sensitive.

I will look forward to Orion's continued input as I have tremendous respect for his experience and thoughts, but for myself, I will be counterbalancing that with the fact that there are many Glasair's with more than 2000 FH and 20 years on them at this point - including several which are regularly abused/campaigned in the SARL and at Reno.

Orion's points in the Personal Cruiser thread about service life vs. economy in production and baseline mechanical properties is exactly the kind of information sharing that I was looking for - the issue for me is to understand how widespread the disbond and core disintegration issue might be and what the primary causes truly are.

If it is basically limited to damage induced failures for the most part, that is different for me than if it is merely a result of aging. I understand and appreciate that we simply do not have, and will likely never have, the kind of information available about aging in the homebuilt composite fleet that we take for granted in the commercial and military aviation world - but the anecdotal info Orion discovered DOES need to be included in the overall discussion - as does the fact that there are thousands of these structures now, with a lot of flight time and calendar age and a limited number of known failures/breakups.

This is merely my own thinking process on display here, not intended to sway any other person.

BTW, the Personal Cruiser/LaF thread was a goldmine for people coming at this from all points of view in my opinion - respectfully presented and informative.
 

orion

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Obviously there are a couple thousand Glasairs of varying stripes and build qualities flying, some for more than 20 years, and there are other aircraft using LaF cores including much more modern designs (e.g., Vision) - I think I have only heard of one structural failure for the Glasair as a family (a horizontal stab failure if I recall correctly – although Glasair claims there have been no structural failures).

In the absence of contrary evidence, I would typically chalk up failures or issues like these on homebuilts, at least ones as popular/successful, and presumably as well designed as the Glasairs, to assembly error (omitted layup) or poor quality (dry layup, voids, not washing hands after eating fried chicken, etc.). I mean, these are aircraft which are clearly presented as capable of +9/-6 G Ultimate, +6/-4 Limit loads, and I remember watching Bob Herendeen fly the stuffing out of his GIII back in the day.

Did you find that the core degrades over time to such a point that eventually it no longer can effectively separate the skins from a sandwich/structural standpoint? What is the failure/degradation? Do you believe that these type sandwich panels will eventually not be airworthy and we will start to see structural failures as the fleet ages?

Is the Glasair designed in compliance with your thoughts on not having the core material at hard points and interfaces? To your knowledge, was the quality control and prep during fabrication at Glasair in those early days solid enough to address your concerns? I assume so, but haven’t really examined one before closing to know.

If I were to take on this Glasair project I would certainly intend to fly it hard occasionally and to do that I need to not have any little gremlins running around in the back of my head questioning the structural integrity of the beast. My impression of the design and assembly of several kitplanes, including the Glasair, is that they were designed to accommodate a certain amount of stupid builder tricks and still be reasonably strong and safe aircraft – am I assuming too much here?

Is your concern so significant that you would not knowingly fly in an aircraft with LaF cores, or is it more that you would not choose it for any project you worked on? I am not trying to be argumentative here, just want to understand your concerns better. I would be putting myself, my wife, our daughter, and friends and family in this plane if I do this.

Thanks again for your time on this, I really appreciate it.

One minor correction about the number of Glasairs - I don't think the factory sold anywhere near the number of the two place low wing variants as that. The company today references about 2,000 builders, including a significant fraction of the very popular Glastar line. Considering the kit completion rate runs at about 40% (although probably higher now after so many kits have been around for so many years), I'd estimate that the number of actually flying Glasairs to be in the neighborhood of 1,000 or less.

But regardless, yes there are quite a few flying and yes, quite a few for about twenty years. Actually much of the Glasair fleet is that old since factory sales declined in the late eighties and never really recovered to anywhere near their heyday. But despite the age of the fleet, there really is little evidence one way or another how well the line fares as far as the bond integrity of the LaF is concerned. As I indicated in the thread referenced above, there was evidence of core failure as far back as the mid eighties however since the de-bonds did not cause an accident, the factory continued to claim that there are no airframe failures.

But there is a problem with that statement and with trying to extrapolate any form of statistical evidence from this sample: First of all, after spending more than 5,000 hours (or more) building an airplane, no owner is going to go out and put that airplane through any serious form of abuse. Yes, a nearly insignificant handful are (or were) being used for air-shows and racing but those will generally receive meticulous maintenance and care. And even in those cases the planes do not see very high loads. For instance, show announcers often talked about 6G (or higher) maneuvers but the fact is that the highest G most of these is likely to see is maybe four to four and a half Gs. Even tight pylon turns rarely generate more than four.

Then considering the average owner, he is not flying air-shows or racing, so it's unlikely that his airplane is ever subject to higher than normal cruising loads so even if the structure is delaminated, it is unlikely that the average pilot will be able to detect anything has gone wrong. This is what's so insidious about this type of failure - you wont know it's occurred until it's too late. During normal or moderate flight the structure is most likely just fine, even if the core is no longer functional. During higher Gs your controls might not be as effective or might feel a bit sluggish but you're not likely to see any red flags. But if for a moment that airplane is subject to a very high load due to turbulence or abrupt maneuvering, this will be the point where said delamination could make itself evident. Given the potential failure modes, the overstressed unsupported skin could at that point fail catastrophically with no preamble or warning.

I don't think I'm paranoid or overstating the case - I've just seen how easily the glass to LaF bond can fail and have seen said failures in relatively low time airframes. That's enough for me to reccommed that builders spend a few more dollars on material that has proven itself in the application, even if it happens to cost a few bucks more. Let's face it, you'e not using all that much core in a typical airplane anyway - the few dollars more in foam cost should not be a detriment to one's project. If they are then maybe that person has chosen the wrong pastime.

To answer your questions:

1) Given the nature of de-bond and the fact that we do know that the LaF bond is relatively weak even in the best of cases, yes, it can be assumed that the older the airframe is the more chance thee is that more of the core has separated or that the bond integrity is subpar. The failure is the degradation of the bond interface, most usually caused as a function of the brittle nature of the core.

2) Hard to tell right now whether there will be increased actual structural failures as time goes on or not. As a structural engineer who's seen the evidence first hand, I can say that I think the trend may be such. But will I guarantee that it will happen this way? Probably not - just don't have enough hard test evidence to make a statement that blunt.

3) Yes, the Glasair line was designed in compliance with good design practices. I think there are a couple of areas where a rib or bulkhead extends over a core, but from my recollection, not in any critical areas. And yes, the factory did do a pretty good job of adhering to approved procedures and maintained a pretty tight ship in regards to process and quality control. Yes, there were a few questionable things over the years but overall, I think they did better than most.

4) In my opinion, kit design has to include some level of consideration for the dumb builder. The question though is how much? I've often heard companies assume that the builder would be cognizant of the fact that he was building an airplane and thus understand the necessity to keeping to the right procedures and techniques, so any added weight penalties that might fudge on the safe side were avoided. But in practice I've seen some horrible builds so I certainly wold not wish to bet on the builder's side.

5) Well, I have flown in and flight tested Glasairs so I have certainly not avoided the product in the past but I should point out that there is a difference between an airplane like the Glasair, built in a factory with an almost aerospace level procedural process and quality control, versus something like a Vision or similar, built under relatively amateurish conditions. But would I today recommend against the use a LaF product in an airframe? Yes. Would I today avoid a LaF airframe, especially an older one? Yes. Do I have conclusive documented evidence of the potential problems I discuss herein? No. But in the same breath I do have sufficient personal experience that leads me to these conclusions and recommendations. And so anyone can take that in the spirit it's given.
 
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jlknolla

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Minor update

I went back onto the interwebs and it looks like there are 'more than 1,000' Glasair II's of all variants completed and flying, and 'over 300' III's flying, both as of '07 timeframe (latest I could easily find, numbers completed as reported in the Kitplanes 2008 Annual Directory issue). Add to that over 800 GI's were sold and I would estimate maybe 400 of those have been completed and are flying (hard to find that one) - works out to at least 1700-1800 of the Glasair family completed and in service, as of about 4 years ago.

Several have over 2,000 hrs on them, many have more than 1,000 hrs. Certainly not the same level of completions that Van's enjoys (7500+), but pretty good for a plastic airplane.

I also checked the NTSB accident database, 107 accidents for the Glasairs (38 with 1 or more fatalities - 35%) - a quick review suggests that stupid pilot tricks remains the leading probable cause, with unexplained loss of power as the only recurring physical/mechanical probable cause. By comparison, Lancair shows 149 accidents (70 with 1 or more fatalities - 47%), in far less calendar time.

Still ruminating over the data Orion has provided.

Fun side note, Jeff Lavelle qualified at 396.73 mph in his Glasair III for Reno Sport earlier this week, next closest time was a Questair Venture (the ol' flying egg) at 372.375. Lavelle's pace would place him 13th in the Unlimited Class, not bad for a plane you can build in your garage.

Hinton set a new record qualifying speed for Unlimited at 499.160 in Strega.

The time difference between just under 400 mph (GIII) and just under 500 mph at Reno is 15 seconds - mind boggling.
 
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