Stryker F-27

Jim W.,

You should see one fly using a brushless motor (Mega 16/15/4) & 3 cell LiPo battery (Kokam 3S1P/2000mah/15C)! Averages 70-80mph on flat fly by, and around 116mph on a strafing run!

*Warp speed* !!!!!

You can read more about these 'modified' F-27 Strykers at....

F-27 Too fast for Ron

F-27 Stryker - How Far Can You Take it? Clocking my brushless F-27 --

Jim L.

Using - Virtual Access(OLR), ZAP 5.5, & WinXP Pro w/SP2

Not knowing about radio controlled aircraft, but I bet the advent of nickel metal hydride (NiMH) rechargeable batteries has helped, at least for low-end aircraft.

| Not knowing about radio controlled aircraft, but I bet the advent of | nickel metal hydride (NiMH) rechargeable batteries has helped, at least | for low-end aircraft.

Yes, but possibly not as much as you might think.

NiMH cells generally have higher internal resistances than NiCd cells of the same size, so while you generally get more capacity, you also get less power with the same number of cells. The total energy density goes up, but the power density goes down.

(Of course, what most people do is add another cell to counter that effect. I know you claimed that isn't true in that other post, but it is -- more voltage into your plane's motor generally DOES make it go faster. At least until you burn something out.)

But yes, most low end planes now use NiMH cells to power their motors instead of NiCd. But it's the Lipoly cells that are really a big improvement ...

To rephrase, increasing voltage is a bad idea unless you know device specifications.

I appreciate the heads-up about high load current meaning internal resistance causes a problem and allows for some voltage increase.

Something nickel metal hydride batteries have going for them is strong consumer demand in a competitive market. Since their introduction not long ago, the technology has improved rapidly. Currently the AA NiMH batteries are 2300 ma hours. That is already a huge capacity difference over nickel cadmium batteries at their peak. Also, NiMH are much less harmful than NiCd to the environment.

Here is one USA source for tabbed NiMH and other batteries (I ordered from them many times when doing electronics, price was high but service was good). Please feel free to list other sources.

?Ref=65964&Site=US&Cat=30147467 Have fun.

| >(Of course, what most people do is add another cell to counter that | >effect. I know you claimed that isn't true in that other post, but | >it is -- more voltage into your plane's motor generally DOES make | >it go faster. At least until you burn something out.) ... | To rephrase, increasing voltage is a bad idea unless you know device | specifications.

Oh, give me a break. I knew what I was saying, as should most people who read it. As for the specifications, R/C planes often push the motors, especially cheap can motors, way past their specifications anyways, and they still work [but not forever, of course.]

When you buy an `all in one' plane where it comes pre-assembled for $50, sure. In this group, that's the exception rather than the rule. But when you build an electric plane, using your own motor, ESC, etc. increasing the voltage (by changing the battery pack) is a very common way of increasing performance.

To be fair, you generally do know the specifications, and if you're serious about it you've even modelled the setup with something like Motocalc (have you seen Motocalc?

... but the battery pack is just another variable to manipulate as you search for better performance. And even if you don't model it beforehand, it's relatively easy to measure things like current draw [the main concern, rather than voltage, though of course it's affected by voltage] and weight and static thust before you even launch the plane.

| I appreciate the heads-up about high load current meaning internal | resistance causes a problem and allows for some voltage increase.

At some level, this stuff *is* rocket science, but like rocket science, it has already been completely worked out by people way smarter than we are (or at least people with more time to work on it) and so there's really no need to guess at how something will perform anymore.

But I can tell you this -- AA NiMH (or NiCd, for that matter) cells to power an electric R/C airplane are likely to not perform well. They're just too heavy for the modest discharge rates that they'll tolerate. Sure, you could make a plane that works powered by them, but it'll fly very lazily.

| Something nickel metal hydride batteries have going for them is | strong consumer demand in a competitive market.

LiPo too, for that matter.

| Since their introduction not long ago, the technology has improved | rapidly.

1990 or so. Yes, they've improved greatly since then. And many of those improvements have also been applied to NiCd and other batteries. NiCd cells have improved nearly as much as NiMH cells since 1990.

In any event, the future of R/C plane power is not NiCd, and it's not NiMH either. It's LiPo. The right LiPo packs have a higher power density than the best NiCd cells and a higher energy density than the best NiMH packs.

| Currently the AA NiMH batteries are 2300 ma hours.

If you're talking about the highest capacity AA NiMH cells, I've seen cells rated at 2500 mAh at Wal-Mart. But that doesn't matter, because these cells are really unsuitable for R/C airplane power plant use -- their internal resistances are *way* too high. They work nicely for transmitter and receiver packs, but can't handle the power demands for the motor.

In many cases, the higher capacity cells are worse than the lower capacity cells because they get the higher capacity by giving up/reducing other things that decrease the internal resistance or increase the resistance to damage.

| That is already a huge capacity difference over nickel cadmium | batteries at their peak.

Yes, about double. But you cannot discount the internal resistance, and NiCd still has the edge there by a signifigant margin. NiCd cells also last more charge/discharge cycles and tolerate abuse (overcharge, reverse charging, heat) better. There's a reason that NiCd are still more popular in power tools, for example.

| Also, NiMH are much less harmful than NiCd to the environment.

This is really only a reason to buy NiMH if you're too lazy to make sure your NiCds get recycled properly.

Don't get me wrong -- I use lots of NiMH cells. But they're not the final answer to all our battery problems ...

| Here is one USA source for tabbed NiMH and other batteries (I | ordered from them many times when doing electronics, price was high | but service was good). Please feel free to list other sources. | |

?Ref=65964&Site=US&Cat=30147467| Expensive. The local Frys sells 4 pack 2000 mAh NiMH cells for $5 or

10 pack for $10 each on a regular basis. Not good for R/C plane power plant, but great for lots of other stuff.

This is my interpretation of your reply. Let me know if I am making any straw men.

... NiMH are no better than NiCd for radio controlled aircraft

... if you buy NiMH batteries because they are much safer for the environment than NiCds, you are too lazy to properly recycle NiCds

... usually there is no discussion about modifications to ready-to-fly RTF aircraft in this group (especially not cheap RTF aircraft)

... there should be no discussion about NiMH power supplies for motors

... you have seen 2500 mAh AA batteries at Wal-Mart

By the way. At the start, I was clarifying what you thought I said, not putting words into your mouth.

snipped-for-privacy@frenzy.com (Doug McLaren) wrote:

newssvr11.news.prodigy.com!newscon03.news.prodigy.com!newsmst01a.news.prodigy.com!prodigy.com!newsswing.news.prodigy.com!prodigy.net!atl-c02.usenetserver.com!news.usenetserver.com!feed5.newsreader.com!newsreader.com!border2.nntp.dca.giganews.com!nntp.giganews.com!cyclone.austin.rr.com!fe2.texas.rr.com.POSTED!not-for-mail

| This is my interpretation of your reply.

Well, at least you didn't quote my entire post just to add `troll' this time.

| Let me know if I am making any straw men.

You're not really making any straw man arguments here -- at least in a straw man, you attack the argument, but in a different form. In these cases, you're making up completely different positions and then assigning them to me. | ... NiMH are no better than NiCd for radio controlled aircraft

I did not say that. Not even close.

Both have their pros and cons. I tried to cover both, but maybe you missed it. | ... if you buy NiMH batteries because they are much safer for the | environment than NiCds, you are too lazy to properly recycle NiCds

I did not say that. I believe that your error here is called a non sequitur, affirming the consequent.

may be of some assistance.

| ... usually there is no discussion about modifications to | ready-to-fly RTF aircraft in this group (especially not cheap RTF | aircraft)

I did not say that. Though it's reasonably close to accurate -- there's very little discussion about modifying the low-end RTF planes here. There may be more in some other forums, but not here.

I'm not sure how it's relevant, however.

| ... there should be no discussion about NiMH power supplies for | motors

I did not say that. Not even close.

What I did say is that AA NiMH cells are unlikely to perform well when used to power an electric R/C plane -- the power/weight ratio is too low. (Note that this is different from the energy/weight ratio, which is relatively high for a NiCd/NiMH cell.) Yes, you could make an electric plane where the motor is powered by AA NiMH cells, and it could fly. But it's unlikely to have much power beyond what's needed to keep it flying.

There are other NiMH cells that can dump power at a much higher rate. The car racers love their sub-C NiMH cells, for example. But these are very different from your typical AA NiMH cell.

| ... you have seen 2500 mAh AA batteries at Wal-Mart

I did indeed say that.

Looks like you're batting a 0.200 here ...

| By the way. At the start, I was clarifying what you thought I said, | not putting words into your mouth.

If you say so. Personally, I tend to feel like I'm being trolled here, but so be it ...

| ... | >Path: | newssvr11.news.prodigy.com!newscon03.news.prodigy.com!newsmst01a.news.prodigy.com!prodigy.com!newsswing.news.prodigy.com!prodigy.net!atl-c02.usenetserver.com!news.usenetserver.com!feed5.newsreader.com!newsreader.com!border2.nntp.dca.giganews.com!nntp.giganews.com!cyclone.austin.rr.com!fe2.texas.rr.com.POSTED!not-for-mail | >Newsgroups: rec.models.rc.air ...

You snip `much discussion', but then keep my headers? Odd. Did you think the S/N ratio was too high or something?

This is my interpretation of your on-topic meaningful replies.

... there is no clear answer whether NiMH are better than NiCd for radio controlled aircraft

... the fact that NiMH are much less harmful than NiCd to the environment "is really only a reason to buy NiMH if you're too lazy to make sure your NiCds get recycled properly"

... some other forum is more appropriate for discussion about modifications to low end ready to fly RTF radio controlled RC aircraft

newssvr11.news.prodigy.com!newscon03.news.prodigy.com!newsmst01a.news.prodigy.com!prodigy.com!newsswing.news.prodigy.com!prodigy.net!atl-c02.usenetserver.com!news.usenetserver.com!feed5.newsreader.com!newsreader.com!border2.nntp.dca.giganews.com!nntp.giganews.com!cyclone.austin.rr.com!fe2.texas.rr.com.POSTED!not-for-mail

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Hilarious!

Funny how the whole topic of conversation got changed from the praise of one product to a major discussion on the pros/cons of NiCd vs NiMh.

FWIW, I bought the higher voltage 8 cell pack offered by Park Zone and the thing is even more fun than with the 7 cell set up. Both packs are NiMh BTW. I get about 10-12 min with both packs but performance is greater with the 8 cell pack. Upon doing some research into the cost of converting to electric, the initial outlay is still too much for the .40-.60 sized AC I fly. However, for the smaller .010-.20 size, electric is making more sense than ever. Even with the higher initial outlay of funds, the overall cost differential in the long run (no fuel to buy) is appealing. I am also looking into converting an old Guillow's Cherokee 140 kit to electric sometime in the future.

Having a blast!!

Jim W

My wife gave me one of these for xmas. As a begginer, after about 3-4 flying days it's looking a bit battered, but I can get it down safely nowadays with obviously helps.. A great machine - fun, without being too challenging for someone like me with zero experience.

For *MORE* fun with your F-27 Stryker, check out these threads.....

F-27 too fast for Ron

F-27 Stryker - How far can you take it Clocking my brushless F-27 Jim

Is anyone experiencing wing warp after a few flights ? I had a ne

fuselage and after only 3 battery packs the wings were warping upward. After 5 packs it was so severe the plane would not climb

-- umpir

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:mad: Is anyone experiencing wing warp after a few flights ? I had

new fuselage and after only 3 battery packs the wings were warpin upward. After 5 packs it was so severe the plane would not climb

-- umpir

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Hmmm, I was thinking of making the Stryker my first air model. Is this a bad idea?

The wings have some dihedral naturally. I'll compare my "flown airframe with the new in the package one. My solution would be to d the same number of high speed outside loops as inside loops on eac pack. :

-- erashb

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My friend modified my warped fuselage while I was on a business trip.

He also did the same to his Stryker, which he flies with a brushles set-up. Basically, he used 10 minute foan safe epoxy and fiberglas matting. He applied it to the center section where the motor moun tends to break and then on the top and bottom along the junctio between the fuselge and wing root.

Additionally, taking the advice of a past thread, he put two ol Stryker carbon rods ( cut to about 8 inches ) one on each top side passing from the motor mount, along the top of the fuselage along th "cockpit". The motor mount was then bolted on so that it actually sit on the two rods. This really strengthened that area.

We flew both planes yesterday in a stiff wind of at least 10-15 mp with gusts that actually would cause the stock motor planes to jus hover into the wind at full throtle. Did loops and a few tight turn and there was no visible warpage !!!!

By the way, the brushless set-up wasn't phased by the wind at all. I fact it damn near climbed out of sight !

Thanks for everyone's help

-- umpir

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Here?s a fe

-- mpodde

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