Grumman Tiger Divorcées

[A64Pilot]

I can’t get past that they are glued together, I’ve got too much experience with “disbonding” to trust airplanes that are glued together. How long does the glue last?

I seem to remember something about purple glue?

 

Edited April 11, 2022 by A64Pilot

[gwav8or]

I can’t get past that they are glued together, I’ve got too much experience with “disbonding” to trust airplanes that are glued together. How long does the glue last?
I seem to remember something about purple glue?
 

This was one of the reasons I sold mine. Grumman supposedly fixed the debonding issues early on but a couple years ago there was an incident where one of the planes had a tail surface that debonded in flight. Lucky he did crash and die.


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[BKlott]

2 hours ago, A64Pilot said:

I can’t get past that they are glued together, I’ve got too much experience with “disbonding” to trust airplanes that are glued together. How long does the glue last?

I seem to remember something about purple glue?

 

We had an early Cheetah for four years and the only deboning issue we had was with the cowling. It needed to be re-glued every year. Imagine that! In a location known for heat, temperature changes and vibration, the glue would fail. 
 

Years later during an interview with Roy Lopresti, in a moment of self reflection he commented that they (Grumman American) had a mindset that they were building a bonded airplane. He said they went to great lengths to find innovative ways to bond parts together that could have better been connected “mechanically”, using nuts, bolts or rivets. It was an interesting and reflective comment.

[carusoam]

I love polymers… they make great disposable packaging… 

Unfortunately, they are often sensitive to heat, and oxygen… and UV light and all kinds of environmental things…

Gluing a plane together probably came with an expected lifetime… based on lab data…

Extending the life based on real data… Somebody has to be first, and lead the pack…

 

PP thoughts only, not an organic chemist…

Best regards,

-a-

 

[A64Pilot]

15 hours ago, BKlott said:

We had an early Cheetah for four years and the only deboning issue we had was with the cowling. It needed to be re-glued every year. Imagine that! In a location known for heat, temperature changes and vibration, the glue would fail. 
 

Years later during an interview with Roy Lopresti, in a moment of self reflection he commented that they (Grumman American) had a mindset that they were building a bonded airplane. He said they went to great lengths to find innovative ways to bond parts together that could have better been connected “mechanically”, using nuts, bolts or rivets. It was an interesting and reflective comment.

When the AH-64 was built, bonding was cool so a whole bunch of stuff was bonded, and a whole lot of my time was spent either rebonding, or replacing dis-bonded parts. See I thought they debonded, but a McDonald Douglas Engineer corrected me. To this day I have a main rotor blade grip, about a 30 lb chunk of Grade 5 Titanium because the data plate disbonded and went away, I could prove it’s serial number by historical records but that wasn’t good enough, so it became scrap

God knows what it cost to produce this thing. Been simple to Laser etch a serial number, Lasers were cool back then too.

 

Edited April 12, 2022 by A64Pilot

[philip_g]

21 hours ago, A64Pilot said:

To me canopies with a clear window over your head are HOT, you have to have a sun shade, which negates the utility of a clear top

A Rans RV for example is just too hot for me. But I don’t live in the Great white North either.

The second you crack that canopy a couple inches all your troubles go away. There are certainly more Grumman per Capita here than anywhere in the world. I can think of at least 6 on the ramp. They really are great hot weather airplanes. Its like free ac.

 

I flew a pipersport one time. That thing wasike a cooker. And in a turn with the position of the air intake you lost air flow.

Edited April 12, 2022 by philip_g

[exM20K]

23 hours ago, A64Pilot said:

To me canopies with a clear window over your head are HOT, you have to have a sun shade, which negates the utility of a clear top

 

and there is the reason, in addition to a flawed fashion sense, that glider pilots typically wear floppy sun hats.   BTDT.

Solo'd in a mogas-fueled Cheetah many moons ago.  Survived.  Actually enjoyed flying that plane.

-dan CMEL + PP-G

[Fly Boomer]

Salty old dog checked me out in one in 196x (something).  Doing steep turns he said "watch the upper surface of the wing -- when it wrinkles, let off the stick a bit".

[kris_adams]

I had an AA1B many moons ago.  Almost everyone that joined the Grumman Gang would ask about debonding.  Almost like how we get question after question about Mooney parts availability nowadays.  From what I recall, most of the bonding issues happened relatively early in the life of the planes and I never talked to anyone that had personally seen it in the last couple decades.  Lots of old tales and stories told 2nd and 3rd hand.  I totally agree that my non-evidence is just as anecdotal as people saying there are issues lol.  I'd buy a Tiger in a minute without any fear.  I loved my little Grumman for that period in my life. 

Now from a stability and ROC perspective, it definitely didn't compare to my Mooney.  Unfortunately I've only ridden in a Tiger 1x back in the 70s so I have no insights to compare a more similar model to the Mooney.

[carusoam]

Going rivet free has some aerodynamic advantage…

Imagine if they went rivet free and used a laminar flow wing…

Or…..

Imagine Flush rivets on a laminar flow wing… that would be the best…!

Go Mooney!

Best regards,

-a-

[BKlott]

On 4/11/2022 at 9:25 PM, carusoam said:

I love polymers… they make great disposable packaging… 

Unfortunately, they are often sensitive to heat, and oxygen… and UV light and all kinds of environmental things…

Gluing a plane together probably came with an expected lifetime… based on lab data…

Extending the life based on real data… Somebody has to be first, and lead the pack…

 

PP thoughts only, not an organic chemist…

Best regards,

-a-

 

My Dad used to always kid our fellow Grumman owners with “Stay away from acetone clouds”.

[EricJ]

22 hours ago, BKlott said:

My Dad used to always kid our fellow Grumman owners with “Stay away from acetone clouds”.

The A&P school I went to had two Yankees.    The story on one of them was that the owner was prepping it for new paint and was pretty liberal with the paint stripper.    Somebody then pronounced it unairworthy because there was no way to inspect that the bonds hadn't been ruined by the stripper, so it got donated to the school.

I've no idea whether that was true, but that was the story they had about it.   

 

[BobbyH]

On 4/12/2022 at 5:24 PM, carusoam said:

Going rivet free has some aerodynamic advantage…

Imagine if they went rivet free and used a laminar flow wing…

Or…..

Imagine Flush rivets on a laminar flow wing… that would be the best…!

Go Mooney!

Now you've gone and done it , what you say is true but good composite work has many advantages beyond aerodynamics.  When designed properly (Not black aluminum) then putting large sections together can be almost seamless. They can be designed to be more robust than aluminum, higher load bearing at a lower weight.  Think of NO leaking fuel at seams and rivets.  But to get these excellent properties you need to do a lot of autoclave curing under pressure and high temperatures, which makes this method a little too expensive for GA.  A good bonding job is actually much stronger and has lower stress concentrations than rivets.  Unfortunately most shops have not been trained in the proper materials and process needed to ensure long-term bonds.  This includes some of the problems Grumman ran into. 

So all my long windedness to say, . . . the great balance for small GA aircraft is flush rivets on a laminar flow wing.  Maybe I did hear that somewhere . . .

Go Mooney!

Bob (former aerospace composites engineer)

[carusoam]

Fantastic details Bobby!

Thanks for sharing them.

Best regards,

-a-

[201Steve]

On 4/15/2022 at 8:57 PM, BobbyH said:

But to get these excellent properties you need to do a lot of autoclave curing under pressure and high temperatures, which makes this method a little too expensive for GA.

They are expensive…. and big…. And heavy… and heavy….

[201Steve]

Here is one we hauled for GE Aerospace

[Hank]

2 hours ago, 201Steve said:

Here is one we hauled for GE Aerospace

That's That's big autoclave. But I work in injection molding, and this is what delivery of a large molding machine looks like:

Yes, there's a second driver at the back. Well over 100 tires. 

[dominikos]

I got my private in cheetah, bought M20J 5 hours later. IMHO, it’s a much easier plane to fly, much more stable and actually easier to land, if you stay on the numbers. It’s a safe environment (is it), so I can admit that I did 6 go arounds in Cheetah on x-country as I didn’t realize that I did land the plane, it felt that I bounced. Love landing mooney. 

[Pilot boy]

On 4/9/2022 at 5:41 PM, steingar said:

Had I a Tiger I doubt I would switch unless it was a 201 or better.  The Tiger is just a fairly similar aircraft.  That said, I routinely lampoon the Grumman Gang.  A similarly equipped Tiger sells for a lot more than the short body Mooney that can handily outrun it.  Indeed they sell for 201 prices, and at that point it isn't even a comparison.

I wanted a Tiger and I switched to Mooney for 2 reasons but mostly first reason:

1.    I couldn’t find a decent priced Tiger.  2 yrs ago they were all $60k and up and I just couldn’t get my hands on any they’d sell fast.  If they had anything like a 430W they were getting up to $70/80k area. Going short body Mooney w manual gear made it way easier to find one w good avionics at a fair price I had many more to choose from...even though they were selling very fast as well.  I actually found one from word of mouth thru local avionics mechanics I had talked to.  They knew an owner thinking of selling his E.

2.  I flew in a Cheetah with someone who owned one and a side from great visibility I thought it felt cheap.  The fiberglass wing pieces or something just didn’t look right.  The Mooney seemed much more stout and better built.