What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Another Radial RV-8R

VA Maule

Well Known Member
Hello all I've just about talked myself into following in Brain Kelley's footsteps, but before I get too far down the "rabbit hole " I would like to get some advice from some experienced RV's. First I don't know anyone with a RV-8 I'm based at KFVX in Farmvile VA and I would like to meet and discuss some particulars that Mr Kelley had to overcome with his build. Second the standard gear is intended to accommodate up to a 76" prop while the Rotec R3600 is designed to swing an 84" I spoke with Grove Gear about the possibility of taller gear and they suggested using a one piece set that would also reduce stress on the fuselage if the gear web was 5" or more wide where it's mounted , Now on a quick build kit would it be advisable or possible to add additional gear towering ( example adding an additional front & rear tower panel about an inch fore & aft of the factory installed ones.)

Thanks in advance for your help, as many more questions will follow. Morgan D.
 
How about contacting Brian and going down for a visit? Seems he has the answers to the questions you have. Nothing beats standing there with the plane and noodling over whats required. He is the man to noodle with.
 
plus, spare parts are likely!!!

..I'll bet with any project like his, he probably has Version 1,2, 3 or 4 of many components that just didn't quite work out!!
....you can benefit not only from his engineering, and design process, but his scrap bin too! ( if only for a starting point):rolleyes:
 
Thanks for the quick replies ,and getting up with Brian is defiantly on the list. He chose to deal with the prop issue by going CS-electric I'm thinking of taller gear and the recommend 84". As I read in here there has been some discussion about gear "weak links" my thought is this may be elegant solution as I would prefer to avoid electric prop control. So as to be as simple mechanicaly as posable. I have been fllowing Radial Conversions FB for about 18 months and am quite familiar with Brian's posts. Besides I do not want to copy his just to be inspired by it, after all the goal is to unique and have that radial KOOL factor.
 
I'm pretty sure (not positive) Brian Kelly is in Port Orange, Florida, which is just south of Jacksonville. Find him here under the memberlist and start emailing him. Or better yet, get hold of Vlad. I'll bet he'll fly you anywhere.:D:D:D
 
A 150 HP O-320 will fly an 8 just fine, provided C of G is kept proper.
If you lower the nose a few degrees in flight you will still exceed VNE.
Only climb rate will be reduced along with a slightly longer take off roll.

The only question is do you really want the radial and the work to build the aircraft.
I might go for a flight in a few different 8's if I was not 100% sure about the Rotec.
 
Last edited:
I spoke with Grove Gear about the possibility of taller gear and they suggested using a one piece set that would also reduce stress on the fuselage if the gear web was 5" or more wide where it's mounted , Now on a quick build kit would it be advisable or possible to add additional gear towering ( example adding an additional front & rear tower panel about an inch fore & aft of the factory installed ones.)

Before someone starts modifying aircraft structure, it is a good idea to have an understanding of what the load paths in the current design are , and what the structure does to handle those loads.

If you used a one piece gear, the load transfer to the fuselage would be totally different than the original design so the additional structure you propose could very likely just be added ballast.
 
Anybody know about the dependability of the Rotec, overhaul interval, etc.? I seem to recall there are some issues. Its hard to beat the Lycoming and its varients for dependability
 
go Lycoming???

if you like radials, go Lycosaurus!!!
...the 'little' R680 puts out 225 hp, and as an added bonus, will be 100 years old .....before too long! :)

ummm, ok, at 500+ lbs, you're gonna need a little ballast in the tail!:eek:
 
F1R-Yes I believe I do want the radial, hopefully someone will allow me to experience their 8 (I'll do gas & lunch)

rvbuilder2002- This was actually suggested by Robby Grove of Grove Gear. My intent here is to tap into the wealth of knowledge here to get the understanding.

brad walton- Rotec had some cylinder base stud issues in the beginning and changed the hardware grade & some cam gear rivets issue prior to 2009. Warranty 12 mo. or 200 hr. after first start and or 3 years after delivery.
 
Hey Scott,
If Vans ever start supporting the Rotec I'll be building another RV!

(I think once is enough for a home-Brewed engine installation).
 
rvbuilder2002- This was actually suggested by Robby Grove of Grove Gear. My intent here is to tap into the wealth of knowledge here to get the understanding.

I am not sure what exactly Robby recommendation was, but my point was that if a one piece gear was added, the transfer of the vertical bending loads into the fuselage would be very different than for separate gear legs. It is possible that the gear towers would not even be needed. At least not for the type of loads they are used for now.
 
Last edited:
A 150 HP O-320 will fly an 8 just fine, provided C of G is kept proper.
If you lower the nose a few degrees in flight you will still exceed VNE.
Only climb rate will be reduced along with a slightly longer take off roll.

The only question is do you really want the radial and the work to build the aircraft.
I might go for a flight in a few different 8's if I was not 100% sure about the Rotec.

All those things you say about the effect of less power are true, but you missed the top speed, which is pretty important.

It will fly, but 180hp 8s will leave it in the dust. The 4s and 6s fly well on 150hp but the 8 is a bigger, heavier airplane. The RVs are all about performance. 30hp is a BIG difference-almost 20%. I have never seen an -8 with an O320. I think the 150hp would be disappointing compared to the standard setup.
 
I am not sure what exactly Robby recommendation was, but my point was that if a one piece gear was added, the transfer of the vertical bending loads into the fuselage would be very different than for separate gear legs. It is possible that the gear towers would even be needed. At least not for the type of loads they are used for now.
I think Scott meant to say "wouldn't" be needed? If that's correct, I have to wonder if Van would consider making a switch to one-piece gear on all -8's... Those gear towers in the fuselage make the footwell quite cramped, in my opinion.

Of course, everything is a tradeoff, so switching to one-piece gear and losing the gear towers inside may lead to a less desirable change elsewhere...
 
Oops....

I think Scott meant to say "wouldn't" be needed? If that's correct, I have to wonder if Van would consider making a switch to one-piece gear on all -8's... Those gear towers in the fuselage make the footwell quite cramped, in my opinion.

Correct I meant would not

Of course, everything is a tradeoff, so switching to one-piece gear and losing the gear towers inside may lead to a less desirable change elsewhere...

Exactly my point.
The gear tower structure might be able to be deleted, but other structure likely would have to be added.
Doing this type of mod. properly, requires a full engineering evaluation with the new gear and then drop and pull tests to verify the engineering.
 
Thanks for the quick replies ,and getting up with Brian is defiantly on the list. He chose to deal with the prop issue by going CS-electric I'm thinking of taller gear and the recommend 84". As I read in here there has been some discussion about gear "weak links" my thought is this may be elegant solution as I would prefer to avoid electric prop control. So as to be as simple mechanicaly as posable. I have been fllowing Radial Conversions FB for about 18 months and am quite familiar with Brian's posts. Besides I do not want to copy his just to be inspired by it, after all the goal is to unique and have that radial KOOL factor.

Morgan,

First off congrats on deciding to be different! I could go into the why's and how's for a long time, but I'll just say I went down every road you've talked about. In my experience and the by using the experience of other Rotec owners I can definitely say that the CS prop is the only way to go with this airframe and that engine. The 84" prop is mainly used on WWI replicas and frankly it's way to much prop for the engine. Will it fly? Yes, but at a major speed disadvantage. I'll post a couple of pictures from my flight back from Sun N Fun. You can see all of the data there from my current installation. I still have some development to do, mainly with cooling. I'm currently overcooling. Once that is solved I should pick up another 5 kts. Please feel free to call me and chat. I'll pm you my personal number. For everyone concerned about performance. It's not a 180hp rv, but she's plenty fast for me!

All the best,
BK
3103c93842e21e9ca414fe7270436738.jpg
[/IMG]
87135f4e1d79e559fca068692c3607a5.jpg
[/IMG]
 
Last edited:
The thought behind the potential added gear tower panels is the gear would be 9" taller and 6" wider, with a 5" top flang . Since the tower is set for 3" stock flang would it not make sense widen the loading area accordingly as the fore & aft forces of longer gear needs more support to compensate for the increased leverage at the attachment point. Remember my objective is prop clearance.

I believe my thought process here corresponds with the "Breaking News " and related threads on gear bolts.

This aircraft will be operated off a grass strip adding to the stresses on the gear.
 
Morgan, to your original question...yes, it is possible to design new gear tower structure optimized for longer, one-piece gear legs with increased clamp width. It wouldn't look like the current gear tower.

No, a QB fuselage wouldn't work well. At the basic level, increased clamp width will require a new WD-822, and you'll need to move F-802K-1 forward. Those two things trigger a cascading series of additional mods. It is certainly nothing as simple as scabbing on some new fore and aft gear tower panels.

You do have preview plans?

I assume you're basing an 84" prop assumption on tip speed. Although a 74" prop at 2700 and a 84" prop at 2400 have near identical tip speeds, there is a large difference in disk area. Consider what that does to the pitch requirement given the same HP.

....after all the goal is to unique and have that radial KOOL factor.

No, the goal is a practical airplane which happens to be very cool.
 
Last edited:
Morgan, to your original question...yes, it is possible to design new gear tower structure optimized for longer, one-piece gear legs with increased clamp width. It wouldn't look like the current gear tower.

No, a QB fuselage wouldn't work well. At the basic level, increased clamp width will require a new WD-822, and you'll need to move F-802K-1 forward. Those two things trigger a cascading series of additional mods. It is certainly nothing as simple as scabbing on some new fore and aft gear tower panels.

You do have preview plans?

I assume you're basing an 84" prop assumption on tip speed. Although a 74" prop at 2700 and a 84" prop at 2400 have near identical tip speeds, there is a large difference in disk area. Consider what that does to the pitch requirement given the same HP.



No, the goal is a practical airplane which happens to be very cool.

I agree with Dan, you can start down a rabbit hole very easily when modifying a pre punched quick build. Changing a load bearing structure can require changing multiple parts of the original kit. Looking at alternatives to the propeller provides more solutions with minimal engineering changes. The good thing is I've already done the leg work on the propeller and adaptor. Both companies have the drawings and can reproduce the parts for you. The cost of the GT electric propeller is about half that of an MT prop. And the controller works better than anything I've ever seen.

BK
 
....would it not make sense widen the loading area accordingly as the fore & aft forces of longer gear needs more support to compensate for the increased leverage at the attachment point....

Nothing intrinsically wrong with such a modification, if you don't mind some added weight, but it does require a considerable bit of engineering. Not back-of-the-envelope engineering, but real engineering, not only internet forum stuff. It'll include some analysis and some testing.

Even then you'll have a heavier, slower airplane. But at least it'll hold together.

Dave
 
Got my RV grin over the weekend from stinson46 in his RV-8 "Crazy Woman ". He let me have some stick time and I must say even from the back seat these little plans are great!!!!!!! :D
 
The collection of parts

After a long and challenging journey the collection of parts and pieces was officially ordained an airplane January 9, 2023 DAR Darrel Watson. Who was introduced to me by Mel here on VAF , Thank you Mel.

Every comment made previously in this thread was taken into consideration. The several suggestions for real engineering and structural analysis to the proven Vans RV-8 were heeded, in fact I meet with the legend himself Mr.Jack Norris for him to review my proposed changes and check my math, sadly I won’t be able to show him the finished product. He was truly a gentleman.

Another fine fellow I’d like to publicly say thank you to is Brian Kelly (flyboykelly) for being the inspiration for the second Radial RV-8R , letting me get a really close look at his @ Sun-n-Fun and information he shared.

With first flight quickly approaching and phase 1 testing coming soon. I’ll post the results here
 

Attachments

  • AA01FDC9-BFFB-4338-92D3-9BC3C2AC6682.jpg
    AA01FDC9-BFFB-4338-92D3-9BC3C2AC6682.jpg
    328.3 KB · Views: 661
Wow! Congrats and kudos to you for doing the hard work to get to this point!

Now who's going to be the first to go electric...... :D
 
Wow! Congrats. Looks like you went with the Rotec. Brian changed to the Verner V-9 and I haven't seen a post for a while to hear how he likes it, how the change went, etc. Would love an update from him.

What did you end up doing on the gear?
 
RV-8R one piece gear

Steve to answer your question on the gear . It a custom one piece from Grove that’s almost 9” longer than stock and 5” wide through the fuselage . A routed channel runs the full length 1/4” wide, 5/16” deep for the break line to run in. Robby Grove and I had numerous conversations about the additional clamping strength that would be required and reinforcement of the lower outboard portion of the gear tower structure. It has a slightly wider spread angle than the standard Vans legs. In the pictures you can see the much larger clamping hardware I fabricated and had heat treated to the same Rockwell hardness as the kit supplied parts.

I’ll look for the pictures of the reinforcement of the outboard lower part of the gear towers if you’re interested.
 

Attachments

  • 0D489F8A-9C14-4DB4-ACB2-56D0380F490B.jpeg
    0D489F8A-9C14-4DB4-ACB2-56D0380F490B.jpeg
    1.1 MB · Views: 318
  • 7AFD90DF-3C0A-4A50-988D-A954491009DB.jpeg
    7AFD90DF-3C0A-4A50-988D-A954491009DB.jpeg
    804.2 KB · Views: 277
  • 6006EE03-384A-4032-9AE9-297D3A0641A1.jpeg
    6006EE03-384A-4032-9AE9-297D3A0641A1.jpeg
    732.1 KB · Views: 217
would love to see a picture with all the cowl pieces on.

After a long and challenging journey the collection of parts and pieces was officially ordained an airplane January 9, 2023 DAR Darrel Watson. Who was introduced to me by Mel here on VAF , Thank you Mel.

Every comment made previously in this thread was taken into consideration. The several suggestions for real engineering and structural analysis to the proven Vans RV-8 were heeded, in fact I meet with the legend himself Mr.Jack Norris for him to review my proposed changes and check my math, sadly I won’t be able to show him the finished product. He was truly a gentleman.

Another fine fellow I’d like to publicly say thank you to is Brian Kelly (flyboykelly) for being the inspiration for the second Radial RV-8R , letting me get a really close look at his @ Sun-n-Fun and information he shared.

With first flight quickly approaching and phase 1 testing coming soon. I’ll post the results here
 
Wow, looks really cool! Can you post more photos of the plane...would love to see more of it. Congrats!

Cheers,
Bob
 
Weights?

Very cool. My hangar mate has an -8 kit that may want one of those.

I am interested in empty weight and what you list as max take-off weight.
 
Nice work!

Hi Morgan,

We met a few times while I was in Farmville flying in IAC competitions. You picked my brain for the few tidbits left and you told me of your intent to built the radial RV. It's great to see that your dream is coming along. Can't wait to see the finished product.
 
Steve to answer your question on the gear . It a custom one piece from Grove that’s almost 9” longer than stock and 5” wide through the fuselage . A routed channel runs the full length 1/4” wide, 5/16” deep for the break line to run in. Robby Grove and I had numerous conversations about the additional clamping strength that would be required and reinforcement of the lower outboard portion of the gear tower structure. It has a slightly wider spread angle than the standard Vans legs. In the pictures you can see the much larger clamping hardware I fabricated and had heat treated to the same Rockwell hardness as the kit supplied parts.

I’ll look for the pictures of the reinforcement of the outboard lower part of the gear towers if you’re interested.

I chuckle at the fact that it's still in the blue protective tape, but has already marked its territory.
 

Attachments

  • 0D489F8A-9C14-4DB4-ACB2-56D0380F490B.jpeg
    0D489F8A-9C14-4DB4-ACB2-56D0380F490B.jpeg
    1.1 MB · Views: 190
but has already marked its territory
That gave me quite a chuckle :D

Well done, congrats Morgan!!
That’s one ship I’d love to have in my stable, a rotary -8… next life, for sure ;)
 
Last edited:
Why not… that would be even more exotic than a simple radial, wouldn’t it be :D

PS
Thought about the Anzani, or some other one…
 
Last edited:
Cowling (s)

Here’s some cowling pictures as requested. “Dishpan inner portion is rather long compared to the classic radial design but it conceals all of the goodies that don’t need to be receiving large quantities of cooling air flow or contributing to drag by being in the path of exiting cooling air. The full NACA style cowling will (hopefully) eventually reduce the drag to a reasonable value. The full cowling will direct all cooling air through the same basic exit ramp configuration as Dan Horton has on his with an adjustable damper but more like a butterfly valve as opposed to a flap. The standard aluminum exist ramp was used as a pattern to make a stainless version with extended sidewalls to eventually be support structure for the butterfly valve arrangement. Initially I’ll just utilize the dishpan and speed ring to simplify the inspection process during early testing.
 

Attachments

  • 1C6ABD80-B7E1-4254-8056-D82A251B03A9.jpeg
    1C6ABD80-B7E1-4254-8056-D82A251B03A9.jpeg
    667.4 KB · Views: 233
  • 6BB8512F-420B-46ED-9201-3A15DEA17745.jpeg
    6BB8512F-420B-46ED-9201-3A15DEA17745.jpeg
    719.2 KB · Views: 239
  • B7CA72CC-F666-4AFE-9C4C-6E59E9EC99DE.jpeg
    B7CA72CC-F666-4AFE-9C4C-6E59E9EC99DE.jpeg
    660.6 KB · Views: 244
More cowling

Speed ring & exist ramp. Bottom section of dishpan is not installed and another picture of the speed ring properly polished
 

Attachments

  • 1F48402E-17F3-4CDF-A9F6-B39A078DAD0C.jpeg
    1F48402E-17F3-4CDF-A9F6-B39A078DAD0C.jpeg
    616.1 KB · Views: 186
  • 6D6E4205-2468-4E34-BE99-DCBB847601A3.jpeg
    6D6E4205-2468-4E34-BE99-DCBB847601A3.jpeg
    715.7 KB · Views: 184
  • 4B308BE3-1F71-447A-A7EA-94AEEA1284E2.jpeg
    4B308BE3-1F71-447A-A7EA-94AEEA1284E2.jpeg
    630.6 KB · Views: 181
Empty Weight

plehrke glad to accommodate . Here’s a picture of her on the race car scales. Empty weight including 2.5 gallons of engine oil ( gotta have an ample supply for Territory markings y’all know how radials are) came in @ 1177 pounds with an empty CG @ 76.1 , add my weight + 10 gallons of fuel and the CG falls @78.80
 

Attachments

  • D3AF5DBB-0BAF-4CC0-9CE8-EBE6B23B41B3.jpeg
    D3AF5DBB-0BAF-4CC0-9CE8-EBE6B23B41B3.jpeg
    762.8 KB · Views: 221
Morgan, could you run through the modifications to accommodate the one-piece, lengthened gear? Although the radial catches the eye, the gear is the interesting structural change.
 
More on the gear

Dan I appreciate your interest and It’ll take a couple of posts to incorporate the pictures that tell the story much better than my feeble writing skills (that little paper clip thingy is my hero)
Firstly my intent is to maximize the radial’s ability to handle a larger diameter prop. 86” would have been the better choice per Mr. Norris’s checking of my figures, we (much more him than me) determined a Whirlwind G-284 @84” ground adjustable would be a very good option since the pitch could be adjusted to accommodate the combination engine and aircraft . I also wanted to minimize alliterations the airframe particularly the line of the standard forward top skin and baggage door. These 2 criteria’s necessitated the longer main gear. This first picture is the only real “TLAR” figuring to confirm approximate gear length
Next picture is the dimensions determined from the mock up
Next is the maximum cross section 1&1/4”x5” fully radiused of the center section of the one piece gear that can be fitted between F-802K-1 and F-802L-1 both F-802M replaced with a 1/8” x2” flat strap to keep the F-822-1 ( forward floor ) from oil canning
From here Robby Grove and I started talking to determine how to make it work

Looks closely and you can see the replacement strap for the intercostal rib in the cross section picture
 

Attachments

  • 9B9C22AB-5FE0-43C9-A98C-4407A1A7914A.jpeg
    9B9C22AB-5FE0-43C9-A98C-4407A1A7914A.jpeg
    713.4 KB · Views: 113
  • 4A88CE5F-4390-467A-A223-928BC299A281.jpeg
    4A88CE5F-4390-467A-A223-928BC299A281.jpeg
    948.4 KB · Views: 123
  • FB2F9B61-3C9C-4FD1-8C39-5DC7C0D3CBDE.jpeg
    FB2F9B61-3C9C-4FD1-8C39-5DC7C0D3CBDE.jpeg
    543.6 KB · Views: 137
Last edited:
Back
Top