What is a hardwood propeller mean?

[kevin king]

Is a Rev Up a hardwood propeller?

[Istvan Travnik]

If you consider the Canadian Maple* as hardwood, yes.
You consider beechwood as hardwood (Xoar), however not the hardest. Maybe it is the most "grateful" as a wooden prop material.
As I know, hornbeam is hardest, but mass producers do not like it. (Minimal touching the ground can rip it all along the blade...

*European maple (whiter than Canadian) is surely not hardwood, some like it for minimal weight.

[Mike Danford]

Hardwood only means the wood came from a leafy tree, not an evergreen (or needle bearing) tree.

Has nothing to do with “how hard” it is.  Balsa is a hardwood.

Given model props are successfully made of poplar, I really think nearly any wood is fine.  Poplar is light and not terribly strong.

There are “soft” and “hard” maples.  Soft maples weight a bit less (though typically more than poplar) and are more prone to nicks and dents.  All are suitable for props.

I’ve never seen softwoods used, but honestly I don’t know why not.  Spruce has the best strength to weight, is generally tight grained and should make very fine props. 

[kevin king]

Thanks guys. The reason I ask is because in the Fox 36 combat engine manual Duke says to use a 'hardwood propeller'. I've heard these motors can throw a prop so I most definitely make double sure, as i prefer not to ' Put an eye out'.
Hopefully I can attain the 120mph like it said on the Sterling Winder's box.

😁

[Ty Marcucci]

I am not positive4, but I believe back in the 50's one company made pressed balsa props and coated them with "plasticote" or some such...does Tornado sound familiar?  They tended to be a dark brown color.   Yes, I know balsa wood is a hard wood.

[Ty Marcucci]

Thanks guys. The reason I ask is because in the Fox 36 combat engine manual Duke says to use a 'hardwood propeller'. I've heard these motors can throw a prop so I most definitely make double sure, as i prefer not to ' Put an eye out'.
Hopefully I can attain the 120mph like it said on the Sterling Winder's box.

😁

The white plastic props were notorious for coming apart..  Instructions came with them telling you to boil them for ten minutes before use..The yellow Tornado props hung in there, but bent back at the tips.

[Brett Buck]

Is a Rev Up a hardwood propeller?

  In your context, I think that means "wood", as opposed to nylon (Top Flite) or polyester (Tornado yellow/silver).

   Good luck on the 120 mph, sounds like excellent "ad copy" to me.

         Brett

[bill bischoff]

So, don't use props from needle-bearing trees. How about ball bearing-trees? And what about Christmas trees? At times they are both needle-bearing and ball-bearing trees. Where does that leave bushing trees, or "bushes"? 

[Doug Moisuk]

So, don't use props from needle-bearing trees. How about ball bearing-trees? And what about Christmas trees? At times they are both needle-bearing and ball-bearing trees. Where does that leave bushing trees, or "bushes"? 

Don’t quite your day job. 😈😈😈😈

[John Rist]

So, don't use props from needle-bearing trees. How about ball bearing-trees? And what about Christmas trees? At times they are both needle-bearing and ball-bearing trees. Where does that leave bushing trees, or "bushes"? 

 

[kenneth cook]

           Kevin, when using one of the MK engines. DO NOT USE Master Airscrew propellers. My buddy had one throw a blade and it went through his cheek and into the roof of his mouth. Not only did this leave a very bad facial scar, it took hours of surgery to repair the roof of his mouth. He couldn't talk correctly for quite some time. The back of the Master Airscrew props have hollow cavities, on one of these cavities is where the blade departed.
      I've also had APC propellers throw a blade on a MK engine. This caused the front of the crankshaft to break off. Use the D-1 hub props when using one on a MK engine.

[Dave Harmon]

Correct about the MA props.
A friend of mine was running up an engine in the pits with a 3 blade MA....one blade let go and the entire nose of the airplane ripped off and it flew over the club house and landed in the parking lot.
It missed him....and me....thank God.

[kevin king]

Use the D-1 hub props when using one on a MK engine.

Ken what is a D-1 hub prop?

[doug coursey]

Ken what is a D-1 hub prop?

I  THINK IT STAMPED INTO THE HUB

[Dave Hull]

I looked thru the APC website and found nothing on the "hub marking."  A quick look thru my stash of APCs revealed some prop hubs molded with D-1, but most are molded with C-2. The only ones I readily came across with D-1 were the 7.8 pylon racing series and the 6.5 diameter series, which may have been originally designed for .15 CI pylon racing?

Maybe I'll give them a call and see if they will clarify the purpose of this marking. They do provide a list of rpm limits for different types of props (in the form of diameter multipliers) but I did not see mention of the hub markings.

Dave

[bill bischoff]

I think people were using the 7.8x6 narrow blade racing prop (as you described) on .36 fast combat. As you know, the hub is rather substantial.

[Air Ministry .]

Balsa'sw HARDWOOD .

Im thinking you mean HEART wood . Heart Timber .

If a fibre glass or crabon prop had all the fibres running off through the edge on one side ,
It might not ' set ' under load , the same as a straight laid side .

GRAIN in Timber Props is LIKE THAT . Should be matched and even , for a Top Comp. Prop. at least .
Low rpm muckabouts its hardly critical . A LOT of old Top Flight props are rather SOFT Timber ,
Particularly the rounded blade ones .

THAT is definately NOT Heart timber .

[kenneth cook]

            Bill is correct in regards to the 7.8x6. This prop is not out of the question to use on a MK VI. This prop though has underwent some blade changes over the past few years and the newer is thinner bladed which I don't care for. I was using a 8x8 APC when my prop blade let go. I took a picture and sent it to APC. They informed me that prop I was using was rated for the rpm's but they have no way of monitoring prop useage. Therefore, they mentioned a few factors can contribute to blade failure which they can't control such as transporting, ground strikes and even starting with a chicken stick. I don't use a chicken stick, my prop never hit the ground at anytime and it wasn't damaged in transport. They also mentioned inspecting the prop for stress fractures which initially show up as white striations  which can form at the tips and prop to hub intersection.

[FLOYD CARTER]

Many types of wood have been used for model props.,   The late Clarence Bull  (B,Y&O props) showed me a storage shed full of some beautiful beech wood, to be turned into model props.

[Air Ministry .]

            Bill is correct in regards to the 7.8x6. This prop is not out of the question to use on a MK VI. This prop though has underwent some blade changes over the past few years and the newer is thinner bladed which I don't care for. I was using a 8x8 APC when my prop blade let go. I took a picture and sent it to APC. They informed me that prop I was using was rated for the rpm's but they have no way of monitoring prop useage. Therefore, they mentioned a few factors can contribute to blade failure which they can't control such as transporting, ground strikes and even starting with a chicken stick. I don't use a chicken stick, my prop never hit the ground at anytime and it wasn't damaged in transport. They also mentioned inspecting the prop for stress fractures which initially show up as white striations  which can form at the tips and prop to hub intersection.

Indeed . Had a blade fly off a Winsor 3 Bl 12 x 6 a few months back . At least the wings are still o.k. . The rest didnt fare to well . Was loading up in a bit of wind . Was totally unexpected .

A wind up was a silk coverd spruce capped I Beam wing , over your knee . The Tips will go a few inches up and down , In their ' Working Range ' of load bearing . THE POINT BEING

IF you grab the blades firmly and carefully , you can ' test ' the resilance , ant a reasonable estimation of ' working load ' Which is a lot higher in big bumps on a stunt machine going hard .

IF theres a flaw , its fairly evident . Test a few ' discard ' junk props , to get a feel for it / them .  But many components can do with a ' non distructive ' test . IF it ' destructs ' them ,
they were obviously flawed . SOMEHOW .

There has been known to be sabotage .
We wont coment on that . OBVIOUSLY .

[Paul Smith]

Thanks guys. The reason I ask is because in the Fox 36 combat engine manual Duke says to use a 'hardwood propeller'. I've heard these motors can throw a prop so I most definitely make double sure, as i prefer not to ' Put an eye out'.
Hopefully I can attain the 120mph like it said on the Sterling Winder's box.

😁

Duke's advice was given in the days of plastic and nylon props which were inferior to the wood props of the day. Carbon fiber and fiberglass props had not been developed yet.

With Fox Mark VI's and Nelsons it is possible to work OK on the ground and in level flight, then throw a blade in quick turns due the stress of gyroscopic precession.

[kevin king]

 Paul, are you refering to the wood blades that operate ok at level and throw a blade in a quick turna due to GP?

[Howard Rush]

So, don't use props from needle-bearing trees. How about ball bearing-trees? And what about Christmas trees? At times they are both needle-bearing and ball-bearing trees. Where does that leave bushing trees, or "bushes"? 

Do people still celebrate Christmas?  I thought there were laws now against donning gay apparel.

[Ken Culbertson]

 

Do people still celebrate Christmas?  I thought there were laws now against donning gay apparel.

You have that backwards. 

Ken

[Air Ministry .]

G15s & Rossi's threw blades when the props went soft , at a world champs early 70s . Hot Day & 20 / 22 000 rpm's .
Hard to cut the  other guys streamer , when the blades have fallen off .
Were the Tornado & Top Flite NYLON 7 x 6s . was a panic for f glass props , so , a turning point .
Dont think they had any Taipan Glass reiforced Nylon , the Black Ones . There . Was said 24.000 was about the lot for them .
Threw the Big End , at that speed . Previous abrupt halts in Combat wouldve been the cause .

[Double Deuce]

I am pretty sure the Tornado Plasticoat props were blanked from Cotton wood and then it and the Plastic were squeezed and heated in steel dies to cure. Never knew what the coating was.

In their day, they were wonderful props but the years caught up, the coating dried, and hp went up on the engines and the blades came off quite often.

Double Deuce

[kevin king]

So much for wood props being safer. After putting the prop on the shaft one blade fell off in my hand. it was an older oil soaked blade with no noticable damage. The only other prop i had was a Master Airscrew and it worked fine for the break-in.

[Steve Helmick]

I am pretty sure the Tornado Plasticoat props were blanked from Cotton wood and then it and the Plastic were squeezed and heated in steel dies to cure. Never knew what the coating was.

In their day, they were wonderful props but the years caught up, the coating dried, and hp went up on the engines and the blades came off quite often.

Double Deuce

I used some Tornado Plasticoat props back in the day, before TF came out with their speed props. I was told that the Plasticoat props were actually balsa impregnated with phenolic resin...what they still use to make phenolic/linen and phenolic/paper round bar and slabs. Nasty stuff to machine. Nobody's favorite.

Sometimes at Boeing, I had to turn phenolic/linen bolts on a lathe. Tolerance on the grip was .0006" and length (height) of the head was +/- .001". Nobody else figured it out, and I wouldn't tell them how I made them look like they were molded. That was 747 weight reduction program. They said they got 6,000 lbs off each airframe.  Steve