Ramz

Hello all. I have read tons of info about guys putting OS 25FX's, Norvel 25's, MVVS 28's and what not in their Shrikes but has anybody ever installed a OS25 VF (it's the 25 size ducted fan engine that they quit making a while back) on a shrike? I know of a somewhat local guy who installed a OS25VF on his Sig Wonder and he got 155 mph out of it. i just got done building my shrike with the OS25VF but i have to scrounge up some radio gear for it. I can't wait to try it. i'm gonna use an 8x6 or 8x7 and hope to get about 150+ mph. Do you guys think this is possible?

jwoolridge

Nope it's physicaslly imposible. The prop (8x6) would have to turn 26400 rpm to do that in a perfect world. Now factor in drag (double the speed you quadruble the drag) you need about 31000-33000 to get that kind of speed and there ain't no 25 that will do that with an 8x6. Also the wonder and shrikes are not speed planes as such they can go but they usually max about 70 or 80mph. My OS 25 LA powered wonder max's at about 70mph level and about 80mph out of a dive. Sorry to burst your bubble but you better go back to the math tables and find another plane if you want that kind of speed. With that engine I'd say you might get 100-110mph if you build it light, thin the wing a bit and run a 7x7 prop with a pipe. Hope all this helps in some way

Quick Crash

Well, check out some of the posts from GOOTROD and DARWIN. They are getting speeds in the 125-145mph range with a .25 and .32

They seem to have done an accurate job of determining speed, but like I said read their posts and decide for yourself. I downloaded a video of Charlie flying his norvel powered shrike 10, rather it was going 130, I don't know, but it CERTAINLY was faster than 80-90.

Mike Connor

My Feedback: (5)

My experience is that a Shrike is a clean and fast airplane. My video camera and timers calculated the Shrike 40 at 170+ mph unloading at approx. 20,000 rpm with a 8 pitch prop. While there is a margin for error because of parallax I don't think I am too far off. This claim may not be a fact but what I believe to be true.

MyWay

OS made a 25vf and a 25 vf df. The vf df has more advanced timing and likes to run on a apc 7/7 at high rpm. The 25vf has conservative timing and likes to run on a apc 7/8 . Either version are strong runners with the pipe set properly. Expect speeds of about 140 mph with these motor/prop combos. The df motor will run the 7/7 apc 20000 rpm+ and the vf motor will run the 7/8 about 18000rpm. Just go do it.

MyWay

Trust me, if you could turn 33000 on a 8/6 prop on a shrike 10 you would be approching 190mph, however the plane would probably blow apart at about 160mph. I have had both the sig wonder and the shrike 10. The wonder is about 25mph slower than the shrike 10 with the same prop/engine combination.

Darwin

last summer Charlie (Gootrod) and I ran a bunch of tests with the Shrike 10, using different props, pipes and engines. We used radar guns and doppler speed software to measure speeds.

With either the 25FX or the Norvel 25, we easily achieved 120 mph. The 32SX turns an 8X8 prop about 19000 rpm in-flight and would routinely give me 140 mph. I maxed out at 145 on a few runs. However, I could not break the 150 mph barrier with this combo.

So while I disagree with jwoolridge that the Shrike maxes out at 80 mph, I do agree with him that drag becomes a big factor at speeds approaching 150, and it will be difficult to get over 150 mph with the Shrike (with the same motors) due to its draggy design.

Lately I have been flying 1/12 scale Reno racers with the 32SX and the speed increase was dramatic. These little planes will easily do 150+ with cheap motors like the 32SX. I believe it is because the drag is much reduced in these slippery designs. Compare the Shrike (weight 3 lbs, wing area 329 sq. in) with the Reno racers (weight 3 lbs, wing area 230 sq. in) plus the wing on the Reno racers is much thinner (1 inch at root, 1/2 in at tip) than the Shrike. Reduce the drag and you will break the 150 mph barrier!

I still enjoy flying the Shrike, but if you want to go beyond 150 mph with the same inexpensive engines, you will need to fly less draggy airframes.

Darwin

Charlie E

My Feedback: (1)

Hello Ramz-to-tha-z,

First of all, I also disagree with jwoolridge. Just as Darwin mention, we both did allot of testing last summer and acheived some good speed from these little planes. Now if you power the Shrike with a OS 25 LA you will probably max out at around 80 or 85 mph on a good day. I once had a OS 20 FP on a Shrike which maxed at 80mph. Now if you place a power plant on her that will turn a 8x7 or 8x8 prop around 19,000 rpm hang on and enjoy the rush.
All I can say is watch the Shrike II video here on RCU and make up your own mind.


Charlie

SeacretsOceanCity

Hey Darwin,does that Reno land hot with that wing loading?

Darwin

Yes, they do land hot!! But thats just part of the fun, now, isn't it?

Just keep the grass clipped short, keep some speed on final and they will slide smoothly to a stop (providing you don't overshoot).

Darwin

WMB

My Feedback: (1)

Darwin, who makes the Reno kits? They look fun. Mike

Darwin

Hi WMB,

The kits are from AirKill products in Sacramento, CA. They have a web site: [link]http://www.airkill.com[/link] .

If I remember correctly, they are about $70 each. They are listed on the web site's "Combat" page, but most people build them for 1/12 scale racing. The building instructions show how to build them for either combat or racing.

Darwin

gusser

Hey folks....I'm thinking about glassing my shrike .10. I have an 0s25fx for power. Any suggestions as to thickness of the cloth to be used??? Hopefully it wont slow it down too much....whadaya think???