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Sep 29, 2016, 10:31 PM
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Thanks, Dave. You are now at the top of the "Good Guys" list. Looks like a straight forward build. Should be fun.
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Sep 30, 2016, 12:10 PM
DavidsPlanes
doxilia's Avatar
Dave,

first of all, many thanks for sharing these plans of this rather unique looking classic - much appreciated!

Second, after spending a little time last night looking them over, I have come to understand the following:

1) The G60 was the original design from which the G40 was produced via a scale down of the larger model. In doing so, the wing was kept the same in planform without a need to re-loft the rib profiles by starting the 40 size wing at R4 (instead of R1) and extending it to R13 rather than ending it at R11 where the 60 size ends - yes? This produced an identical planform wing using the same rib set with only a need to add 2 smaller ribs toward the tip of the wing (R12 & R13).

2) On the 60 size wing plan there is mention of wing tips for the G60 at R11, G40 at R13 and a third wing "G4" at R12. What was this intermediate wing span for and what was the G4?

3) The "Groover 4" wing uses a continuously variable 15% root-> 18% tip semi-symmetrical airfoil. The G60 is similar but slightly thicker at the tip as it ends at R11 instead of R12 of the G4. The G40 is correspondingly thinner as it starts at R4 and ends at R13 - presumably ~0.5-1% thinner overall.

4) What is the meaning of the "Groover 350" reference on the vertical fin?

5) Without scaling the plans and opening them up in CAD, I came to the following specs:

Groover 40 ("400 squares"):
OAL = 43.75"
RC = 9.75"
TC = 5.62"
Wing Span = 53.3"
Panel Area = 185 sq in
Wing Area = 370 sq in
Spinner = 1.75"

Groover 60 ("490 squares"):
OAL = 50.6"
RC = 11.1"
TC = 6.4"
Wing Span = 61.6"
Panel Area = 270 sq in
Wing Area = 540 sq in
Spinner = 2.00"

Based on these specs, I'd say that the G40 falls more likely in the "modern" category of a 25-32 size model (<400 squares) while the G60 is in the 45-55 size category (~550 squares). The G40 would certainly fly well on a piped 25 or muffled 32-35. Likewise, the G60 would fly well on a piped 45 (or even strong 40) or a muffled 50-55.

Please feel free to comment or otherwise correct me wherever necessary.

TIA, David
Last edited by doxilia; Sep 30, 2016 at 01:20 PM.
Sep 30, 2016, 01:37 PM
AMA 32832 - SPA L27-VRCS 1138
Dave Swanson's Avatar
Thread OP
David, your observations are very astute!

1) You are right on the money regarding the G60 vs, G40 planform.

2) The intermediate wing is a bit of a mystery. I am not sure if Nathan ever built this version.

Your final observations are dead on also.

The Groover "60" and "40" are very petite planes for their relative "recommended" engine displacement and would fly very well with good motors of smaller displacement. The Groover 60 is a very competent sport flyer with the OS 61FSR at high idle!

But the over powered versions along with the light weight (6.1 lbs for my 60 size) are so much fun it is addictive! You will never fly a model that does consecutive knife edge loops as easily as the Groover with an overpowered engine!

I had the digital imaging company scale up the planform by 15% for a "90" size version. Nathan had never went down this road. The "90" size would fly very well with a strong 60 I am sure.

David, I really appreciate you comments! Thanks Dave
Sep 30, 2016, 03:37 PM
Registered User
Quote:
Originally Posted by Dave Swanson
There were 14 requestors of plan sets and all have been distributed. I am available to answer questions. Lets see some more Groovers out there in the future!
1/8" balsa fuselage sides? I didn't see them labeled and I never imported into CAD to have a better look.


Mark
Sep 30, 2016, 04:07 PM
DavidsPlanes
doxilia's Avatar
Quote:
Originally Posted by mmattock
1/8" balsa fuselage sides? I didn't see them labeled and I never imported into CAD to have a better look.


Mark
Mark,

it appears so. There is really no need for anything more. Also, these are "smaller" classics.

One interesting note I caught was that it appears the original had a foam core under the rear deck sheets. In practice, I see no need for one but some additional formers in the tail boom should be added to support the sheeting which could also be 1/8" instead of the 1/16" over foam core sides and 3/16" top. The front top deck appears to use 1/4" sides and 1/8" top.

David
Sep 30, 2016, 04:58 PM
Registered User
So David, when are you going to start burning ribs? I'll take a set of each.

Thanks Dave, this is a real treat.

Dave

All these Daves and Davids sounds like Thanksgiving at my Gramma's house back in the day. she'd holler out for Dave or John and get either no responses or five.
Sep 30, 2016, 05:20 PM
AMA 32832 - SPA L27-VRCS 1138
Dave Swanson's Avatar
Thread OP
Quote:
Originally Posted by doxilia
Mark,

it appears so. There is really no need for anything more. Also, these are "smaller" classics.

One interesting note I caught was that it appears the original had a foam core under the rear deck sheets. In practice, I see no need for one but some additional formers in the tail boom should be added to support the sheeting which could also be 1/8" instead of the 1/16" over foam core sides and 3/16" top. The front top deck appears to use 1/4" sides and 1/8" top.

David
Both my 40 and 60 have foam core under the deck sheets. Personally I like it this way, but for reasons you all would understand my approach to building Groovers will be as a purist, and will duplicate Nathan's original as closely as possible. I do not expect anyone else to build them the way I will. Do not worry I will not criticize any departures made by builders!



There is also foam "cores" in the wing i center sheeted center section so the rubber bands would not deform the wing. This eliminated the need to fiberglass the center section.

Last edited by Dave Swanson; Sep 30, 2016 at 05:29 PM.
Sep 30, 2016, 07:12 PM
Build more, websurf less
FlyingW's Avatar
Dave,

The Groover looks like a beautiful plane. It is great to see these classics in the air.

I cannot get out of my mind the story about the fluttering stab that came off the plane in an earlier post in this thread. I'm very glad you get her down safely and it is a testimony to a good design and skillful piloting, but how did you have elevator control if the control horn was on the side that came off? Maybe the horn was still connected to the elevator joiner?

Thanks,

Paul
Sep 30, 2016, 07:24 PM
AMA 32832 - SPA L27-VRCS 1138
Dave Swanson's Avatar
Thread OP
Quote:
Originally Posted by FlyingW
Dave,


I cannot get out of my mind the story about the fluttering stab that came off the plane in an earlier post in this thread. I'm very glad you get her down safely and it is a testimony to a good design and skillful piloting, but how did you have elevator control if the control horn was on the side that came off? Maybe the horn was still connected to the elevator joiner?

Thanks,

Paul
There was no elevator control whatsoever. I controlled the rate of descent with throttle only and guided her in without a scratch. The gods were smiling on us that day!
Oct 01, 2016, 08:26 AM
Its not IF... Its WHEN.
The.Timinator's Avatar
Many Thanks to Dave and David for the information.

Any idea what the wing sections are?

Cheers

Tim
Oct 01, 2016, 08:54 AM
DavidsPlanes
doxilia's Avatar
Quote:
Originally Posted by The.Timinator
Many Thanks to Dave and David for the information.

Any idea what the wing sections are?

Cheers

Tim
Tim,

The airfoils look like they were hand drafted. The 60 size wing plan show some details on how Nathan went about it.

A couple of posts up I mentioned that the foil appears to be a continuously variable 15% to 18% semi-symmetrical section.

David
Oct 03, 2016, 11:15 AM
Registered User
aviationf4u's Avatar
That plane looks like it would be a blast to fly. Thanks for sharing!
Oct 03, 2016, 08:37 PM
AMA 32832 - SPA L27-VRCS 1138
Dave Swanson's Avatar
Thread OP
ANNOUNCEMENT!!! There is another Nathan built Groover residing in Texas!

I am waiting with baited breath for Pete to add to this post!! Come on Pete! Spill the beans!
Oct 03, 2016, 09:07 PM
Registered User
Hi Dave,
Here are some pictures of my Groover built by Nate. I think it has been 15 or more years since it has been in the air. The old FSR felt stiff. I think it has an old JR PCM radio in it on 53mhz. Maybe between projects this winter I should get it ready to fly again.

73s
Pete
Oct 09, 2016, 08:18 PM
AMA 32832 - SPA L27-VRCS 1138
Dave Swanson's Avatar
Thread OP
My daughter took these videos today. Enjoy!

Groover 10/9/2016 Flight (1 min 5 sec)


Groover 10/9/2016 Flight (2) (0 min 39 sec)


Groover 10/9/2016 Flight (3) (0 min 29 sec)


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